WO2007058438A1

WO2007058438A1 - Electronic parts packages

Info

Publication number: WO2007058438A1
Application number: PCT/KR2006/004413
Authority: WO
Inventors: Young-Il Lee; Jong-Weon Park; Yun-Min Cho
Original assignee: Amosense Co., Ltd.
Priority date: 2005-11-18
Filing date: 2006-10-27
Publication date: 2007-05-24

Abstract

The present invention relates to an electronic part package capable of effectively radiating heat. A heat radiating member is buried below the mounting region of the light emitting device of the substrate so as to be separated from the mounting region of the light emitting device in a vertical direction, and is exposed to the lower surface of the substrate. A heat transfer member, which has thermal conductivity higher than that of the substrate, is formed between the mounting region of the light emitting device and the heat radiating member. Accordingly, since the substrate includes an effective heat radiating structure, it is possible to quickly radiate heat generated form the light emitting device.

Description

ELECTRONIC PARTS PACKAGES

Technical Field

[1] The present invention relates to an electronic part package, and more particularly, to an electronic part package capable of effectively radiating heat to the outside.

[2]

Background Art

[3] Light emitting diodes (hereinafter, referred to as LEDs) are semiconductor devices that are capable of providing various colors. A light emission source of the LED is formed of various compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. At present, the semiconductor devices have been widely applied to electronic components in the form of packages.

[4] Generally, the criteria for determining properties of LED devices are color, brightness, and the intensity range of brightness. The properties of the LED devices are determined by the compound semiconductor materials that are used in the LED devices. Furthermore, the properties are significantly affected by the structure of the package on which chips are to be mounted.

[5] A common lamp type LED package and a surface mount type LED package are shown in FIG. 1.

[6] A lamp type LED package 10 shown in FIG. IA includes two lead frames 3a and

3b. A metal electrode surface having a cup shape is formed over the lead frame 3b. An LED device 5 is mounted on an upper part of the lead frame 3b. The lamp type LED package 10 is packaged by a hemispheric case 7 formed of transparent molding resins.

[7] Meanwhile, a surface mount type LED package 20 shown in FIG. IB is provided with a package body 11 that is formed of a molding epoxy resin. The package body 11 includes a cavity having a predetermined inclination angle. The cavity is formed in a region that corresponds to a mounting region of a light emitting device in which an LED device 15 is to be mounted. The LED device 15 is mounted in the mounting region of the light emitting device of the package body 11. The LED device 15 is connected to a pattern electrode (not shown) by wires 13.

[8] In the lamp type LED package 10, the hemispheric case 7 acts as a lens to control brightness distribution. In particular, the brightness distribution can be controlled to be narrow depending on the shape of the case 7. If the distribution of brightness is controlled to be narrow, it is possible to increase the brightness at a predetermined angle. Further, since the light emitted from the light emitting source is reflected on the metal electrode surface, it is possible to increase the brightness. [9] Meanwhile, in the surface mount type LED package 20, the brightness distribution is wide due to the package, and the brightness is low. As described above, the brightness and the brightness distribution are significantly affected by the package structure. If the high output LED device is used to increase the brightness in the surface mount type LED package using the molding resins, the amount of emitted heat is increased due to very low thermal conductivity of the molding resins, thus negatively affecting the package. When the high output LED device is mounted in the package to increase the brightness, a ceramic substrate having higher thermal conductivity than that of the molding resin is used as the substrate for the packages.

[10] However, in the LED package using the ceramic substrate, it is difficult to control brightness and distribution of brightness like in the surface mount type LED package using the molding resin. That is, an injection molding process such as the resin molding cannot be applied to the ceramic substrate due to the properties of the material of the ceramic substrate. The ceramic substrate is formed by using a punching process, a laminating process, or a cutting process. Typically, since the mounting region of the light emitting device of the ceramic substrate is formed by punching so as to have a groove shape, it is difficult to form a lateral side of the mounting region of the light emitting device having a predetermined reflection angle. A description regarding this will be given with reference to FIG. 2.

[11] FIG. 2A is a cross-sectional view of a known LED package that is formed of a ceramic substrate. An LED package 30 is formed of two ceramic substrates 21 and 22. Each of the ceramic substrates 21 and 22 has a structure where a plurality of ceramic sheets is laminated. The ceramic substrate 21 disposed on the lower side of the LED package has a mounting region, on which an LED device 25 is to be mounted, on the upper surface thereof. Electrodes 23, which are connected to the LED device 25 by wires 27, extend from the mounting region to a lower surface of the package through both sides of the LED package. The ceramic substrate 22 disposed on the upper side of the LED package includes a predetermined cavity to surround the mounting region of the LED device 25.

[12] In connection with this, since the cavity for the mounting region of the LED device

25 is formed by using the punching process or the cutting process, the section of the cavity is always vertically formed as shown in the drawing. Due to the above- mentioned characteristics, since the section of the cavity is vertically formed unlike the package that is formed of the molding resins, there is a problem in that it is impossible to form an excellent reflection film.

[13] As a result, in the LED package using the ceramic substrate, it is possible to perform adjustment only by controlling the area of the mounting region of the LED device and the height of the substrate constituting side walls of the LED package. Ac- cordingly, it has been difficult to manufacture the LED package having the brightness and angular distribution of brightness that are capable of satisfying various needs for users.

[14] However, the ceramic substrate is excellent more than the molding resin substrate in terms of thermal conductivity and heat radiation. Therefore, the ceramic substrate, which has excellent thermal conductivity and heat radiation, is used as a substrate for the package in the related art. Further, a semiconductor package for an LED shown in FIG. 2B has been introduced to resolve difficulties in adjusting brightness and brightness angular distribution caused by the vertical structure which is necessarily formed due to the manufacturing process.

[15] At present, because high brightness and high power has been required in the LED package, power consumption is increased. When the power of the LED device is increased, the amount of heat generated from the LED device is also increased. As the amount of heat is increased, it is very important to effectively radiate the heat generated form the LED device. Accordingly, during the time when heat is transferred from the LED device to a final portion from which heat is radiated, it is most important to reduce the thermal resistance.

[16] A method of improving thermal conductivity of package materials may be used to reduce the thermal resistance. In the related art, the substrate has been made of plastic (having thermal conductivity of about 0.3 W/mK), LTCC (having thermal conductivity of about 4 W/mK), Al O (having thermal conductivity of about 20 W/mK), or the like. However, ceramic material such as AlN is substituted for the materials of the lower and upper substrates 21 and 22 shown in FIG. 2B to improve the thermal conductivity of the package material. Since AlN has excellent thermal conductivity and strength, it is possible to use AlN as the material of the LED package. However, when a substrate is made of AlN, the substrate is very expensive and it is difficult to appropriately form an inclination angle required for controlling light in the LED package.

[17] As shown in FIG. 3, the substrate 21 and 22 may be made of LTCC or Al O and a thermal slug 29 may be formed to pass through the lower substrate 21 to reduce the thermal resistance.

[18]

Disclosure of Invention Technical Problem

[19] According to the structure shown in FIG. 3, when an LED device 25 is bonded in the form of a flip chip, it is not possible to insulate an anode 23a and a cathode 23b from each other. For this reason it is not possible to apply to a flip chip. According to the structure shown in FIG. 3, Ag epoxy bonding or eutectic bonding is performed on the LED device 25, and the heat generated from the LED device 25 can be directly radiated to a heat sink (not shown) through the thermal slug 29. However, since Ag epoxy used in the Ag epoxy bonding has low thermal conductivity, heat radiation efficiency is decreased. Further, flatness of a plating layer of the LED package (that is, a plating layer between the LED device 25 and the thermal slug 29) should be adjusted to be 5 D or less to perform eutectic bonding. In the case of the eutectic bonding, a metal layer, which is made of AuSn or the like, for soldering is formed on the lower surface of the LED device 25. In this case, when the flatness of the LED package is 5 D or more, the eutectic bonding is partially performed. For this reason, heat is not appropriately transferred.

[20] According to the structure shown in FIG. 3, the difference in thermal expansion coefficient between the LED device 25 and the thermal slug 29 is large in the cases of both the Ag epoxy bonding and the eutectic bonding. For this reason, when the package is operated, the temperature of the LED device 25 rises up to 12O⁰C, which is the junction temperature. When the LED device 25 is turned off, the temperature becomes normal temperature. The normal temperature may be -4O⁰C during winter. Due to the difference in temperature, the bonding interface between the LED device 25 and the thermal slug 29 cannot endure the thermal stress generated between the LED device 25 and the thermal slug 29 having relatively large thermal expansion coefficient. Accordingly, cracks occur on the bonding interface, so that the LED device 25 is separated. Further, since the thermal resistance is increased due to the cracks, the thermal resistance of the entire package is increased. Since the LED device 25 deteriorates due to the increase of the thermal resistance, the brightness of the LED device 25 is decreased. As a result, the reliability of the LED package deteriorates. In addition, when the thermal slug 29 is inserted into the package, the thermal slug 29 is tilted due to the fit tolerance which is for matal insertion. For this reason, when the eutectic bonding is performed on the LED device 25, the amount of defect increases. Further, even though the bonding is appropriately performed, the LED device 25 is tilted. Accordingly, variation of light direction occurs in the LED device 25.

[21] In other words, when the eutectic bonding is performed to bond the LED device 25 on the thermal slug 29, the reflow is performed by raising a temperature of the package up to 35O⁰C. During the reflow, the only both ends of the LED device 25 on the lower surface thereof are occasionally bonded due to the thermal expansion of the thermal slug 29. In this case, heat is not radiated from the entire LED device 25, and heat is transferred only through the portion of the LED device, which is bonded to the LED package by the eutectic bonding. For this reason, it is not possible to maximize the effect of the eutectic bonding.

[22] FIG. 4 is a table showing simulation results of an LED package (ceramic package) including an LED device of 1 W without a thermal slug (for example, Cu slug) (see FIG. 2B), and an LED package including an LED device of 1 W with a thermal slug that passes through the lower substrate (see FIG. 3) under thermal conductivity of 3 W/ mK and 25 W/mK.

[23] FIG. 5 is a table showing simulation results of an LED package including an LED device of 3 W without a thermal slug (for example, Cu slug) (see FIG. 2B), and an LED package including an LED device of 1 W with a thermal slug that passes through the lower substrate (see FIG. 3) under thermal conductivity of 3 W/mK and 25 W/mK.

[24] In FIGS. 4 and 5, bonding temperature means P-N junction temperature of the LED device 25. The temperature of a metal PCB is temperature in the metal PCB (that is, a PCB on which the LED package is surface-mounted; not shown). A heat radiating plate (not shown) is provided on the lower surface of the metal PCB (not shown).

[25] Referring to the simulation results shown in FIGS. 4 and 5, it is understood that the

LED package with a thermal slug passing through the lower substrate (see FIG. 3) is excellent.

[26] However, the LED package shown in FIG. 3 has problems in that the eutectic bonding is not appropriately performed as described above or the LED device is separated due to the difference in thermal expansion coefficient.

[27] Further, there is a high possibility that the trend of the application of the LED package is proceeded in order of "a simple indicator of an electronic device => a flash lamp of a mobile phone => an indirect illuminator / a backlight unit of an LCD TV => a direct illuminator". Accordingly, the power consumption of the LED package tends to be continuously increased.

[28] In consideration of the application trends, an individual LED package cannot meet needs of a market. Therefore, it is necessary to develop an array type LED package for satisfying high brightness.

[29] However, since the array type LED package has structure in which a plurality of

LED devices is integrated, it is important how effectively heat generated from the plurality of LED devices is radiated to the outside. Further, since the plurality of LED device is integrated, there is a problem that static electricity, surge, and noise in circuits connected to the LED chips should be effectively removed.

[30] In particular, since a plurality of LED device is arrayed in the array type LED package, the array type LED package is larger than the individual LED package in size. In addition, since the array type LED package further includes noise removing circuits, there is a problem in that the array type LED package is larger than the individual LED package due to the mounting of additional components.

[31] The present invention has been made to resolve the above-mentioned problems, and an object of the present invention is to provide an electronic part package capable of effectively radiating heat to the outside.

[32] Another object of the present invention is to provide an electronic part package capable of improving optical efficiency.

[33]

Technical Solution

[34] In order to achieve the above-mentioned objects, according to an embodiment of the present invention, an electronic part package includes a light emitting device, a substrate having a mounting region of a light emitting device on which the light emitting device is mounted, and a heat radiating member that is buried below the mounting region of the light emitting device of the substrate so as to be separated from the mounting region of the light emitting device in a vertical direction and is exposed to the lower surface of the substrate.

[35] In the above-mentioned structure, a heat transfer member is formed between the mounting region of the light emitting device and the heat radiating member. Further, the heat transfer member has thermal conductivity higher than that of the substrate.

[36] In the above-mentioned structure, the heat transfer member is formed in a vertical direction so as to have a cross sectional size larger than or equal to that of the light emitting device. Alternatively, the heat transfer member may be formed in a vertical direction so as to have a cross sectional size larger than the surface area of the light emitting device, and is divided into a plurality of regions. Further, one region, which has a diameter larger than the size of the light emitting device, of the plurality of re gions may be provided beneath the light emitting device.

[37] The heat transfer member may be formed of a ceramic sheet layer.

[38] In addition, the substrate includes a cavity around the mounting region of the light emitting device, and a reflector is formed on the inner surface of the cavity. Further, the reflector is connected to at least one of pattern electrodes formed on the substrate, and the pattern electrodes are electrically connected to the light emitting device. The pattern electrode to which the reflector is connected is separated from pattern electrodes formed in the mounting region of the light emitting device.

[39] The above-mentioned structure further includes a varistor material layer formed on the substrate, first and second inner electrodes that are formed in the substrate and partially overlap with each other with the varistor material layer interposed therebetween, and first and second outer electrodes that are provided in the substrate so as to be separated from each other. The first outer electrode is electrically connected to the first inner electrode and the second outer electrode is electrically connected to the second inner electrode.

[40] Advantageous Effects

[41] According to the present invention, since a ceramic substrate has an effective heat radiating structure, the heat generated from the LED devices can be effectively radiated to the outside. As a result, it is possible to stably operate the LED device.

[42] Since the thermal conductivity of the substrate is increased so as to reduce thermal resistance between an LED device and a final portion from which heat is radiated, it is possible to quickly radiate heat generated from the LED device to the outside.

[43] Since the surface flatness of the substrate can be ensured, it is possible to perform flip chip bonding or eutectic bonding.

[44] Since a plurality of LED devices is arrayed on the substrate and a heat radiating plate made of metal is attached to the lower surface of the substrate, it is possible to obtain high brightness and to effectively perform heat radiation.

[45] Since a semiconductor device for removing static electricity and surge and a circuit for removing noise are embedded in the substrate or surface-mounted on the substrate, it is possible to utilize the space of the package to the maximum extent. Accordingly, it is possible to provide an electronic part package that can reduce the size thereof to the maximum extent and effectively remove static electricity and noise.

[46]

Brief Description of the Drawings

[47] FIG. 1 is a view showing the structure of an LED package in the related art;

[48] FIGS. 2 and 3 are cross-sectional views of the LED package, which uses a ceramic substrate, in the related art;

[49] FIGS. 4 and 5 are tables showing simulation results of the LED package shown in

FIG. 2B and the LED package shown in FIG. 3;

[50] FIG. 6 is a cross-sectional view of an electronic part package according to a first embodiment of the present invention;

[51] FIG. 7 is a cross-sectional view of an electronic part package according to a second embodiment of the present invention;

[52] FIG. 8 is a cross-sectional view of an electronic part package according to a third embodiment of the present invention;

[53] FIG. 9 is a cross-sectional view of an electronic part package according to a fourth embodiment of the present invention;

[54] FIG. 10 is a plan view illustrating an example of an inner electrode shown in FIG.

9;

[55] FIG. 11 is a plan view illustrating another example of the inner electrode shown in

FIG. 9;

[56] FIG. 12 is cross-sectional view of an electronic part package according to a fifth embodiment of the present invention;

[57] FIG. 13 is a view illustrating problems of the electronic part packages shown in

FIGS. 6 to 8;

[58] FIG. 14 is a cross-sectional view of an electronic part package according to a sixth embodiment of the present invention;

[59] FIG. 15 is a cross-sectional view of an electronic part package according to a seventh embodiment of the present invention;

[60] FIG. 16 is a cross-sectional view of an electronic part package according to an eighth embodiment of the present invention;

[61] FIG. 17 is a table showing simulation results of the electronic part package shown in FIG. 14 and the electronic part package shown in FIG. 15;

[62] FIG. 18 is an equivalent circuit diagram of the electronic part packages, which are arrayed, according to any one embodiment of the present invention;

[63] FIG. 19 is a plan view of the electronic part packages, which are arrayed, according to any one embodiment of the present invention;

[64] FIG. 20 is a view showing modified array shape of LED devices shown in FIG. 19;

[65] FIG. 21 is a cross-sectional view showing a portion where three LED devices are arrayed in FIG. 19;

[66] FIG. 22 is a view showing a modification of a metal fin shown in FIG. 21; and

[67] FIG. 23 is a view illustrating a method of forming an inner circuit pattern.

[68]

Mode for the Invention

[69]

[70] Hereinafter, electronic part packages according to preferred embodiments of the present invention will be described with reference to accompanying drawings. A semiconductor package using light emitting diodes, that is, LED package will be described below as an optimal embodiment of an electronic part package.

[71]

[72] (First Embodiment)

[73] FIG. 6 is a cross-sectional view of an LED package according to a first embodiment of the present invention.

[74] An LED package shown in FIG. 6 includes a chip type LED device 32, a lower ceramic substrate 35 on which the LED device 32 is mounted; an upper ceramic substrate 40 that is disposed on the lower ceramic substrate 35 and includes a cavity with a predetermined shape in a region corresponding to a region where the LED device 32 is mounted, pattern electrodes 34 and 36 formed on the lower ceramic substrate 35, and a reflecting plate 44 (may be referred to as a reflection film) that is provided on the inner surface of the cavity formed in the upper ceramic substrate 40 so as to surround the LED device 32. A protrusion 44a, which is hung on the upper end of the upper ceramic substrate 40, is formed at the upper end of the reflecting plate 44.

[75] The lower ceramic substrate 35 may be any substrate as long as the LED devices 32 can be densely mounted on the substrate. For example, the lower ceramic substrate 35 may be made of alumina, quartz, calcium zirconate, forsterite, SiC, graphite, fusedsilica, mullite, cordierite, zirconia, beryllia, aluminum nitride, LTCC (low temperature co-fired ceramic), or the like. The material of the lower ceramic substrate 35 is not limited to specific materials. The lower ceramic substrate 35 is formed of one ceramic sheet (green sheet) in FIG. 6, but may be actually formed by laminating a plurality of ceramic sheets.

[76] The upper ceramic substrate 40 may also be made of the same material as the lower ceramic substrate 35.

[77] As shown in FIG. 6, the protrusion 44a of the reflecting plate 44 is hung on the upper surface of the upper ceramic substrate 40 to some extent. The reason for this is that the area of the protrusion 44a exposed to the outside is enlarged so as to improve the heat radiation effect. The protrusion 44a may be formed in a shape covering the entire upper surface of the upper ceramic substrate 40. As described above, the shape of the protrusion 44a may be modified in various ways in consideration of the heat radiation effect and the shape of the package body. Further, it is apparent that the above-mentioned modifications fall within bounds of the present invention.

[78] The above-mentioned reflecting plate 44 may be used as means that efficiently radiates heat generated from the LED device 32 through the protrusion 44a.

[79] A cavity having a predetermined inner inclination angle (for example, an angle of

10 to 45°, which is required to easily radiate heat) is formed on the lower surface (that is, portion corresponding to a mounting region of the LED device) of the lower ceramic substrate 35. The cavity formed on the lower surface of the lower ceramic substrate 35 may have various shapes. It is preferable that the cavity be formed in the shape of a tapered cylinder.

[80] A plurality of thermal via holes 50a, 50b, and 50c is formed between the light emitting device-mounting region formed on the upper surface of the lower ceramic substrate 35 and the cavity formed on the lower surface of the lower ceramic substrate 35. The plurality of thermal via holes 50a, 50b, and 50c is formed in a vertical direction and separated from each other. Heat transfer members 38 (that is, 38a, 38b, and 38c) made of thermal slug are filled in the plurality of thermal via holes 50a, 50b, and 50c.

[81] The plurality of thermal via holes 50a, 50b, and 50c may be formed to have a circular, quadrangular, or polygonal cross section. [82] Although the number of the thermal via holes 50a, 50b, and 50c is three in FIG. 6, the number of the thermal via holes may be three or more and be integrated into one hole. The middle thermal via hole 50b of the plurality of thermal via holes 50a, 50b, and 50c has a diameter, which is larger than or equal to a size of the LED device 32.

[83] Since heat generated from the LED device 32 is first and most transferred to the position of the thermal via hole 50b, the thermal via hole 50b having a diameter, which is larger than or equal to a size of the LED device 32, is formed beneath the LED device 32. If the heat generated from the LED device 32 is not efficiently radiated to the outside, the temperature of the LED device 32 increases, which causes the LED device 32 to deteriorate. Accordingly, the luminous efficiency is decreased, thereby causing the life span of the LED device to be shortened. For this reason, the thermal via hole 50b is formed beneath the LED device 32 so as to quickly radiate heat. Each of the thermal via holes 50a and 50c may have a diameter that is larger or smaller than the size of the LED device 32.

[84] For example, when a plurality of LED devices 32 is arrayed, the thermal via hole

50b and heat transfer member 38b are formed beneath each of the LED devices 32. Further, the thermal via holes 50a and 50c and heat transfer members 38a and 38c are provided around the thermal via hole 50b and heat transfer member 38b, so that heat generated from each of the LED devices 32 is quickly radiated to the outside.

[85] The pattern electrodes 34 and 36 are composed of an anode electrode 34 and a cathode electrode 36 that are separated from each other. The anode electrode 34 is formed on the upper surface of the lower ceramic substrate 35. The anode electrode 34 is separated from the outline of the thermal via hole 50a so that the anode electrode 34 is insulated from the cathode electrode 36 formed in the mounting region of the LED device. The anode electrode 34 is also formed on the lower surface of the lower ceramic substrate 35. The anode electrode 34 formed on the lower surface of the lower ceramic substrate 35 may extend from the anode electrode 34 formed on the upper surface of the lower ceramic substrate 35. Alternatively, the anode electrode 34 formed on the lower surface of the lower ceramic substrate 35 may be separated from the anode electrode 34 formed on the upper surface of the lower ceramic substrate 35, if it can be electrically connected to the anode electrode 34 formed on the upper surface of the lower ceramic substrate 35. The cathode electrode 36 is formed in a direction opposite to the anode electrode 34. The cathode electrode 36 covers upper openings of the thermal via holes 50a, 50b, and 50c and the inner surface of the cavity formed on the lower ceramic substrate 35. For this reason, according to the first embodiment, the LED device 32 is mounted on the cathode electrode 36. The LED device 32 is electrically connected to the anode electrode 34 and cathode electrode 36 through wires 42. [86] Although not shown, the LED device 32 may be insulated from the cathode electrode 36 by an insulating material, and a conductive material such as Ag epoxy may be interposed between the LED device 32 and the cathode electrode 36. If necessary, a cathode may be substituted for the anode electrode 34 and an anode may be substituted for the cathode electrode 36. In this case, driving power is applied to the anode and cathode in reverse direction.

[87] The thermal slug 46 formed of a conductive material such as Cu or Al is filled in the cavity formed on the lower surface of the lower ceramic substrate 35. The thermal slug 46 serves as a thermal sink.

[88] If the thermal slug 46 is directly filled in the cavity made of ceramic, the thermal slug 46 is hardly adhered to the cavity. For this reason, the inner surface of the cavity formed on the lower surface of the lower ceramic substrate 35 is covered with the cathode electrode 36. When the inner surface of the cavity formed on the lower surface of the lower ceramic substrate 35 is covered with the cathode electrode 36 made of a metal material, it is possible to improve the adhesive property of the thermal slug 46.

[89] When the cavity formed on the lower surface of the lower ceramic substrate 35 is formed in the shape of a tapered cylinder, an inner diameter Dl of the cavity is, for example, 1.0 mm or more, and an outer diameter D2 of the cavity is, for example, 3.5 mm or less. These are example data for an LED device that has a size of 5 by 5 mm. The shape and size of the cavity is modified depending on the size of the LED device 32 to be mounted. For an LED device 32 having a size of 3 by 3 mm, an inner diameter Dl of the cavity formed on the lower surface of the lower ceramic substrate 35 may be, for example, 0.3 mm or more, and an outer diameter D2 of the cavity may be, for example, 2.0 mm or less so that the thermal slug 46 serves as a thermal sink.

[90] Meanwhile, the lower end of the reflecting plate 44 is slightly separated from the anode electrode 34 and cathode electrode 36. The reflecting plate 44 is insulated from the pattern electrodes 34 and 36. It is preferable that the gap between the reflecting plate 44 and the pattern electrodes 34 and 36 be as small as possible to prevent the light emitted from the side surface of the LED device 32 from being absorbed (leaking) in the body of the upper ceramic substrate 40. As the gap becomes smaller, the amount of the light absorbed in the body of the upper ceramic substrate 40 is decreased. As a result, the brightness of the light is increased.

[91] According to the first embodiment, since the thermal slug and the heat transfer members are formed in the lower ceramic substrate, it is possible to quickly radiate the heat generated from the LED device. As a result, the thermal stress of the LED device is minimized, so that the LED device is stably operated.

[92]

[93] (Second Embodiment) [94] FIG. 7 is a cross-sectional view of an LED package according to a second embodiment of the present invention. When the structure of an LED package according to a second embodiment is compared with that of the LED package according to the first embodiment, the second embodiment is different from the first embodiment in that a reflecting plate 44 is connected with the anode electrode 34.

[95] The lower end of the reflecting plate 44 is connected to the anode electrode 34 so as to prevent the loss of the light emitted from the LED device 32. A method of integrating the reflecting plate 44 and the anode electrode 34 is not specified, and is apparently understood by those skilled in the art without additional description.

[96] Since the lower end of the reflecting plate 44 is connected to the anode electrode 34 in FIG. 7, the second is different from the first embodiment in the structure of the anode electrode 34 and cathode electrode 36.

[97] Referring to FIG. 7, anode electrodes 34 are formed at both ends of the lower ceramic substrate 35 on the upper surface thereof. A cathode electrode 36 is formed in a mounting region of the LED device formed on the upper surface of the lower ceramic substrate 35. The cathode electrode 36 formed on the upper surface of the lower ceramic substrate 35 is separated from the anode electrodes 34 formed on the upper surface of the lower ceramic substrate 35. The cathode electrode 36 is formed on the inner surface of a cavity that is formed on the lower surface of the lower ceramic substrate 35, and beneath thermal via holes 50a, 50b, and 50c.

[98] According to the second embodiment, it is possible to obtain the same effect as the first embodiment. Further, since the light loss is decreased as compared to the first embodiment, it is possible to improve brightness.

[99]

[ 100] (Third Embodiment)

[101] FIG. 8 is a cross-sectional view of an LED package according to a third embodiment of the present invention. When an LED package according to a third embodiment is compared with that according to the second embodiment, the third embodiment is different from the second embodiment in the structure of the cathode electrode 36 and a metal member 52 is provided in the LED package.

[102] Referring to FIG. 8, the cathode electrode 36 is horizontally formed in a mounting region of the LED device formed on the upper surface of the lower ceramic substrate 35. The cathode electrode 36 covers the upper surface of a heat transfer member 38. One end of the cathode electrode 36 extends downward into the lower ceramic substrate 35 in a vertical direction by a predetermined length, and extends in a horizontal direction toward the outer surface of the lower ceramic substrate 35. Then, one end of the cathode electrode 36 extends downward along the outer surface of the lower ceramic substrate 35 so as to be formed on the lower surface of the lower ceramic substrate 35.

[103] Referring to FIG. 8, the metal member 52 is formed on the inner surface of the cavity that is formed on the lower surface of the lower ceramic substrate 35. Both ends of the metal member 52 are separated from the anode electrode 34 and cathode electrode 36 that are formed on the lower surface of the lower ceramic substrate 35. In this case, like in the first and second embodiments, the metal member 52 has the same function as the cathode electrode 36 formed on the inner surface of the cavity that is formed on the lower surface of the lower ceramic substrate 35. Although the metal member 52 is separated from the anode electrode 34 and cathode electrode 36 in FIG. 8, the metal member 52 may be connected to the anode electrode 34 or cathode electrode 36.

[104] According to the third embodiment, it is possible to obtain the same effect as the first embodiment. Further, since the light loss is decreased as compared to the first embodiment, it is possible to improve brightness.

[105]

[ 106] (Fourth Embodiment)

[107] FIG. 9 is a cross-sectional view of an LED package according to a fourth embodiment of the present invention. FIG. 10 is a plan view illustrating an example of an inner electrode shown in FIG. 9. FIG. 11 is a plan view illustrating another example of the inner electrode shown in FIG. 9.

[108] An LED package shown in FIG. 9 includes a lower ceramic substrate 35 and an upper ceramic substrate 40.

[109] A chip type LED device 32 is mounted in a light emitting device-mounting region formed on the upper surface of the lower ceramic substrate 35. A first outer electrode (anode) 34 and a second outer electrode (cathode) 36 are formed in the lower ceramic substrate 35, like in the fourth embodiment. The LED device 32 is mounted on the second outer electrode 36. The LED device 32 is electrically connected to the first outer electrode 34 and second outer electrode 36 by wires 42. Although not shown, the LED device 32 may be insulated from the second outer electrode 36 by an insulating material. The first outer electrode 34 is an anode and the second outer electrode 36 is a cathode. Of course, polarities thereof may be reversed.

[110] The upper ceramic substrate 40 is disposed on the lower ceramic substrate 35. The upper ceramic substrate 40 includes a cavity with a predetermined inclination angle in a region corresponding to a region where the LED device 32 is mounted. A reflecting plate 44 is provided on the inner surface of the cavity formed in the upper ceramic substrate 40 so as to surround the LED device 32.

[I l l] The lower ceramic substrate 35 and upper ceramic substrate 40 may be referred to as substrates. [112] It is preferable that the lower ceramic substrate 35 be made of a varistor material including ZnO as the main material. Predetermined oxides are added to the varistor material to form the lower ceramic substrate 35.

[113] The content of ZnO and the type and content of oxides to be added are shown in Tables 1 and 2. [114] Table 1

[115] [116]

[117] [118] Further, when the lower ceramic substrate 35 is made of LTCC, Al O , and ZnO-

2 3 based varistor, respectively, the thermal conductivity of the lower ceramic substrate 35, and the temperature of the lower end of the LED device are shown in Table 3.

[119] [120] Table 3

[121] [122] As described above, if the lower ceramic substrate 35 is made of a varistor material including ZnO as a main ingredient, it is possible to quickly radiate heat from the lower ceramic substrate due to high thermal conductivity of the varistor. Accordingly, it is possible to lower the temperature of the electronic part package according to the present invention. In particular, according to the fourth embodiment, the lower ceramic substrate 35 is formed of a varistor sheet having high thermal conductivity. For this reason, a process for manufacturing the lower ceramic substrate is simplified and it is possible to more quickly radiate heat as compared to the first to third embodiments.

[123] A via hole 50 is formed in the lower ceramic substrate 35 below the mounting region of the LED device so as to have a size larger than that of the LED device 32. The via hole 50 passes through the lower ceramic substrate 35 in a vertical direction. A heat transfer member 38 made of a conductive material (for example, Ag paste) such as metal is filled in the via hole 50. The via hole 50 in which the heat transfer member 38 is filled may be formed to have a circular, quadrangular, or polygonal cross section.

[124] For example, when the via hole 50 is formed in the shape of a cylinder, the temperature of the LED device 32 is changed depending on a diameter of the via hole 50 as shown in Table 4. The following Table 4 shows the temperature of the lower end of the LED device (that is, an LED chip) when the LED package to which electric power of IW is applied is thermally equilibrated. Accordingly, the via hole 50 is formed to have an appropriate diameter in consideration of the size and optical characteristic of the semiconductor package.

[125] [126] Table 4

[127] Most of the heat generated from the LED device 32 is first transferred to the portion below the mounting region of the LED device in the lower ceramic substrate 35. Accordingly, the heat transfer member 38 is formed below the mounting region of the LED device in the lower ceramic substrate 35, so that it is possible to quickly radiate the heat generated from the LED device 32. For example, when a plurality of LED devices 32 is arrayed, it is preferable that the heat transfer member 38 be formed beneath each of the LED devices 32.

[128] The lower ceramic substrate 35 includes a first inner electrode 52 and a second inner electrode 54. One end of the first inner electrode 52 is connected to the first outer electrode 34, and the other end of the first inner electrode 52 is disposed toward the second outer electrode 36. One end of the second inner electrode 54 is connected to the second outer electrode 36, and the other end of the second inner electrode 54 is disposed toward the first outer electrode 34.

[129] A varistor voltage in the lower ceramic substrate 35 is increased in proportion to a distance between the first inner electrode 52 and the second inner electrode 54. A varistor capacitance in the lower ceramic substrate 35 is increased in proportion to an area of a portion where the first inner electrode 52 overlaps with the second inner electrode 54. That is, it is possible to adjust characteristic of the varistor by using the distance between the inner electrodes 52 and 54. When the number of the inner electrodes 52 and 54 is increased, it is possible to adjust the capacitance of the varistor. The inner electrodes 52 and 54 are formed in pairs in FIG. 9. However, the number of the inner electrodes is not limited, and may be changed depending on the characteristic and capacitance of the varistor.

[130] In FIG. 9, the distance between the inner electrodes 52 and 54 is preferably smaller than the distance between the outer electrodes 34 and 36, which are disposed above and below the inner electrodes 52 and 54, to remove undesirable parasitic components.

[131] An insulating layer 47 made of an insulating material such as glass is formed on the upper surface of the upper ceramic substrate 40. The insulating layer 47 is also formed between the first outer electrode 34 and the second outer electrode 36. When the electronic part package according to the fourth embodiment is surface-mounted on the printed circuit board, the printed circuit board is plated in advance to perform soldering. The varistor is a semiconductor material, and the surface of the varistor is converted into a conductor during the plating. For this reason, a plating layer is formed on the surface of the varistor between the first outer electrode 34 and the second outer electrode 36, which causes a short circuit. Accordingly, the insulating layer 47 is formed on the surface of the upper ceramic substrate 40 and between the first outer electrode 34 and the second outer electrode 36, to prevent the short circuit. The insulating layer 47 may be made of any material as long as the insulating layer 47 is well adhered to the lower ceramic substrate 35 and the upper ceramic substrate 40, and is not corroded by a plating solution during the plating, and has no effect on the color display corresponding to the light emitted from the LED device 32.

[132] The structure of the first inner electrode 52 and the second inner electrode 54 will be described with reference to FIG. 10. As shown in FIG. 1OA, one end of the first inner electrode 52 is connected to a first outer electrode (not shown) and the other end of the first inner electrode 52 is oriented toward a second outer electrode (not shown), in the lower ceramic substrate 35. The other end of the first inner electrode 52 is formed to surround the via hole 50. As shown in FIG. 1OB, one end of the second inner electrode 54 is connected to a second outer electrode (not shown) and the other end of the second inner electrode 54 is oriented toward a first outer electrode (not shown), in the lower ceramic substrate 35. The other end of the second inner electrode 54 is formed to surround the via hole 50.

[133] Accordingly, when the first inner electrode 52 is laminated on the second inner electrode 54, the other end of the first inner electrode 52 and the other end of the second inner electrode 54 overlap with each other as shown in FIG. 1OC.

[134] In FIG. 10, the via hole 50 is shown to have a quadrangular cross section for easy description, and each of the other ends of the inner electrodes 52 and 54 are shown to have a quadrangular cross section with an opening at the center thereof. If the via hole 50 has a circular cross section, each of the other ends of the inner electrodes 52 and 54 have a circular cross section with an opening at the center thereof. The opening of each of the other ends of the inner electrodes 52 and 54 has a diameter larger than that of the via hole 50.

[135] Another structure of the first inner electrode 52 and the second inner electrode 54 will be described with reference to FIG. 11. As shown in FIG. 1 IA, one end of the first inner electrode 52 is connected to a first outer electrode (not shown) and the other end of the first inner electrode 52 is oriented toward the second outer electrode (not shown), in the lower ceramic substrate 35. The other end of the first inner electrode 52 is separated from the via hole 50. That is, the first inner electrode 52 is patterned on a sheet type varistor material layer. In FIG. 1 IA, the first inner electrode 52 is patterned at one corner of the varistor material layer. As shown in FIG. 1 IB, one end of the second inner electrode 54 is connected to a second outer electrode (not shown) and the other end of the second inner electrode 54 is oriented toward the first outer electrode (not shown), in the lower ceramic substrate 35. The other end of the second inner electrode 54 is separated from the via hole 50. That is, the second inner electrode 54 is patterned on a sheet type varistor material layer. In FIG. 1 IB, the second inner electrode 54 is patterned at one corner of the varistor material layer.

[136] As long as the first and second inner electrodes 52 and 54 are separated from the via hole 50, each of the first and second inner electrodes 52 and 54 may have a shape diff erent from a shape shown in FIG. 11.

[137] When the first inner electrode 52 is laminated on the second inner electrode 54, the other end of the first inner electrode 52 and the other end of the second inner electrode 54 overlap with each other as shown in FIG. 11C.

[138] When the inner electrodes 52 and 54 shown in FIGS. 10 and 11 are compared with each other, each of the inner electrodes 52 and 54 shown in FIG. 10 has a larger surface area than the surface area of each of the inner electrodes 52 and 54 shown in FIG. 11. Accordingly, the capacitance obtained from the inner electrodes 52 and 54 shown in FIG. 10 is larger than that obtained from the inner electrodes 52 and 54 shown in FIG. 11.

[139] If the inner electrodes 52 and 54 are too close to the via hole 50, the heat has an effect on the inner electrodes 52 and 54 when heat is radiated through the heat transfer member 38 filled in the via hole 50. For this reason, the inner electrodes 52 and 54 are separated from the via hole 50 with a predetermined distance, in the structure shown in FIGS. 10 and 11.

[140] If temperature, due to the heat radiated from the LED device 32, is 6O⁰C or more, the IV characteristic of the varistor significantly deteriorates. For this reason, it is most preferable that the layer (a region reflecting a varistor voltage) provided between the first inner electrode 52 and the second inner electrode 54 be positioned at a position where the temperature due to the heat radiated from the LED device 32 is 6O⁰C or less. Further, the position where the temperature due to the heat radiated from the LED device 32 is 6O⁰C or less may be determined by using a heat transfer simulation or thermal imaging camera.

[141] Meanwhile, it is preferable that the upper ceramic substrate 40 is made of the same material as the lower ceramic substrate 35.

[142] In the above-mentioned fourth embodiment, the heat transfer member 38 may be formed to have the same structure as the heat transfer member 38 of the first to third embodiments. In this case, the inner electrodes 52 and 54 should be modified, which can be easily performed by those skilled in the art. [143] According to the fourth embodiment, since the package is made of a varistor material, the package has the electrical characteristic of a varistor. For this reason, the heat radiated from the LED device is quickly radiated to the outside due to the heat transfer member and the thermal conductivity of the varistor.

[144] Since the substrate has the electrical characteristic of a varistor, it is possible to efficiently prevent static electricity without separate zener diode or varistor.

[145] The lower ceramic substrate and the upper ceramic substrate are made of the same varistor material. For this reason, the lower ceramic substrate and the upper ceramic substrate are contracted with the same contraction ratio during the baking process and are attached to each other. As a result, it is possible to improve product reliability.

[146] Since the LED package according to the fourth embodiment has structure simpler than that of the LED package according to the first to third embodiments, a method of manufacturing the LED package according to the fourth embodiment is simplified. For this reason, it is possible to improve yield and to reduce manufacturing costs.

[147]

[148] (Fifth Embodiment)

[149] FIG. 12 is cross-sectional view of a LED package according to a fifth embodiment of the present invention.

[150] An LED package according to a fifth embodiment has substantially the same structure as the LED package according to the fourth embodiment. Accordingly, the same elements as those of the fourth embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[151] The inner structure of a lower ceramic substrate 35 according to the fifth embodiment is different from that of the lower ceramic substrate 35 according to the fourth embodiment.

[152] According to the fifth embodiment, a cavity 60 having a predetermined inner inclination angle (for example, an angle at 10 to 45°, which is required to easily radiate heat) is formed on the lower surface (that is, portion corresponding to a mounting region of the LED device) of the lower ceramic substrate 35. A thermal slug 46 formed of a conductive material such as Cu or Al is filled (buried) in the cavity. A heat transfer member 38 is provided between the mounting region of the LED device and the cavity 60.

[153] Each of the first and second inner electrodes 52 and 54 shown in FIG. 12 has the same structure as shown in FIG. 10 or 11. That is, in FIG. 12, the other ends of the first and second inner electrodes 52 and 54 provided in a direction orthogonal to a via hole 50 surround the via hole 50, like in FIG. 10 or are separated from the via hole 50, like in FIG. 11. Further, in FIG. 12, the other ends of the first and second inner electrodes 52 and 54 provided in a direction orthogonal to the cavity 60 surround the cavity 60, like in FIG. 10, or are separated from the cavity 60, like in FIG. 11.

[154] In FIG. 12, the inner electrodes 52 and 54 may be formed only in a direction orthogonal to the via hole 50. Alternatively, the inner electrodes 52 and 54 may be formed only in a direction orthogonal to the cavity 60.

[155] In the above-mentioned fifth embodiment, the heat transfer member 38 may be formed to have the same structure as the heat transfer member 38 of the first to third embodiments. In this case, the inner electrodes 52 and 54 should be modified, which can be easily performed by those skilled in the art.

[156] According to the fifth embodiment, it is possible to obtain the same effect as the fourth embodiment and to more quickly radiate heat as compared to the fourth embodiment.

[157] Before the descriptions of other embodiments, problems of the first to third embodiments will be described.

[158] In the structure where the via holes 38a, 38b, and 38c are formed in the lower ceramic substrate 35 as described in the first to third embodiments, it is difficult to ensure flatness of the substrate during via filling. That is, Ag epoxy is generally used to bond an LED device to a package. Since the Ag epoxy has low thermal conductivity of about 3 WVmK, the Ag epoxy is not suitable for bonding a high power LED device. In addition, if the via holes are not sufficiently filled with material during the via filling, cavities are formed in the via holes as shown in FIG. 13 A, or if the via holes are excessively filled with material, the material protrudes from the via holes as shown in FIG. 13B. Since each of the fourth and fifth embodiments has the structure where via holes are filled with a predetermined material, the above-mentioned problems occur in the fourth and fifth embodiments.

[159] According to the above-mentioned via filling structure, the flatness of portions having via holes in the substrate is not suitable for performing eutectic bonding or flip chip bonding.

[160] For this reason, a structure capable of quickly radiating heat without the via filling structure is proposed in sixth and seventh embodiments of the present invention.

[161]

[162] (Sixth Embodiment)

[163] FIG. 14 is a cross-sectional view of an LED package according to a sixth embodiment of the present invention.

[164] An LED package according to a sixth embodiment is surface-mounted on a circuit pattern (thin pattern made of copper or the like) of a metal PCB (not shown) by soldering.

[165] The LED package according to the sixth embodiment includes a lower ceramic substrate 35 and an upper ceramic substrate 40. [166] Pattern electrodes 34 and 36 separated from each other are formed on the lower ceramic substrate 35. An LED device 32 is mounted on a mounting region of the LED device of the lower ceramic substrate 35. The LED device 32 is provided on one (a cathode electrode 36 in FIG. 14) of the pattern electrodes 34 and 36 with die bonding resin (not shown) interposed therebetween.

[167] The lower ceramic substrate 35 has high thermal conductivity (for example, 50 to

100 W/mK). The lower ceramic substrate is made of a material in which glass for LTCC is added in one of AlN, BN, and BeO, to have the above-mentioned thermal conductivity. Alternatively, the lower ceramic substrate may be made of a material in which one of AlN, BN, and BeO is added in a ZnO-based varistor material. Further, the lower ceramic substrate may be made of a material in which one of AlN, BN, and BeO is added in an MgO-based material.

[168] AlN has thermal conductivity of 180 W/mK and should be sintered in a reducing atmosphere (at high sintering temperature). Accordingly, if AlN and Ag are simultaneously sintered without adding glass for LTCC, it is difficult to form inner electrodes. BN has thermal conductivity of 50 W/mK and should be sintered in a reducing atmosphere (at high sintering temperature). Accordingly, if BN and Ag are simultaneously sintered without adding glass for LTCC, it is difficult to form inner electrodes. BeO has thermal conductivity of 210 W/mK and should be sintered (at high sintering temperature). Accordingly, if BeO and Ag are simultaneously sintered without adding glass for LTCC, it is difficult to form inner electrodes.

[169] If the predetermined amount of glass and the predetermined amount of AlN, BN, or

BeO are mixed with each other, the sintering temperature of AlN, BN, or BeO is decreased until to about 900⁰C. Accordingly, it is possible to simultaneously sinter Ag forming the inner electrodes and AlN, BN, or BeO, and the lower ceramic substrate has thermal conductivity in the range of 50 to 100 W/mK.

[170] In addition, if one of AlN, BN, and BeO is added in a ZnO-based varistor material, it is possible to simultaneously sinter AgPd forming the inner electrodes and AlN, BN, or BeO. The main ingredient of the ZnO-based varistor material is ZnO. Further, Bi O or Sb O is added in the ZnO-based varistor material as sintering agents, so that the ZnO-based varistor material is sintered at about 1000⁰C. If the content of AlN, BN, or BeO is larger than a predetermined critical value (for example, 60%) when one of AlN, BN, and BeO is added in the ZnO-based varistor material, a varistor characteristic of the ZnO-based varistor material is lost after sintering. For this reason, the content of AlN, BN, or BeO should be adjusted to be smaller than the predetermined critical value so as to allow the ZnO-based varistor material to have thermal conductivity in the range of 50 to 100 W/mK and a varistor characteristic. Meanwhile, if it is not necessary to allow the ZnO-based varistor material to have a varistor characteristic, the content of AlN, BN, or BeO may be adjusted to be larger than the predetermined critical value.

[171] A process for manufacturing the lower ceramic substrate 35 is similar to a general process for manufacturing a varistor. For example, additive such as Bi O or Sb O and one of AlN, BN, and BeO are added in ZnO powder so as to adjust the composition of the ZnO powder to a desired composition. While water or alcohol is used as a solvent, the ZnO powder of which composition is adjusted to a desired composition is ball- milled for twenty-four hours to prepare raw material powder. PVB binder, which is used as additive, of about 6 wt% with respect to the raw material powder is dissolved in a toluene/alcohol-based solvent, and the solution is mixed to the prepared raw material powder to prepare formed sheets. After that, the raw material powder and the binder dissolved in the solvent are milled and mixed for twenty-four hours by a small ball mill so as to manufacture slurry. A formed sheet having a desired thickness is manufactured by using a doctor blade method or the like. A conductive paste such as Ag, Pt, or Pd is applied on the formed sheet by using a method of manufacturing a thick film, such as a screen-printing, or a method of manufacturing a thin film, such as a sputtering method, evaporation method, chemical vapor deposition method, or Sol- Gel coating method, so as to manufacture a plurality of sheets on which inner electrodes are formed.

[172] Then, the plurality of sheets are sequentially laminated and compressed. After that, punching, cutting, bake out, and firing processes are performed on the sheets to manufacture a lower ceramic substrate 35 having a desired thickness. The number of sheets used to form the lower ceramic substrate 35 depends on the thickness of the lower ceramic substrate 35. As described above, a raw material is cast by using a doctor blade method and then laminated in accordance with a general process for manufacturing a varistor. As a result, it is possible to form the lower ceramic substrate 35. When the raw material is cast, the variation in thickness can be controlled in the range of 0 to 1 D. Accordingly, it is possible to ensure the surface flatness of a substrate, which makes it possible to perform flip chip bonding or eutectic bonding.

[173] A material such as sapphire or SiC is used on the lower surface of the LED device

32. The thermal expansion coefficient of the material such as sapphire or SiC is similar to the thermal expansion coefficient of the lower ceramic substrate 35. Therefore, it is very stable as compared to when the LED device is directly mounted on a metal as shown in FIG. 3.

[174] A groove is formed at a central portion on the lower surface of the lower ceramic substrate 35. A metal thermal slug 46 is inserted into the groove. It is preferable that a Cu slug having thermal conductivity of about 350 W/mK be used as the thermal slug 46. [175] The thermal slug 46 is attached to a package body that is formed by simultaneously sintering the lower ceramic substrate 35 and the upper ceramic substrate 40. In this case, the package body means what the upper ceramic substrate 40 having a cavity and the lower ceramic substrate 35 without the thermal slug 46 are attached to each other. Although the process for forming the package body is not described in detail, it is apparent to those skilled in the art that the package body is formed by a well known manufacturing process.

[176] To attach the thermal slug 46 to the package body, first, a space into which the thermal slug 46 is inserted is formed on the lower surface of the package body (that is, the lower surface of the lower ceramic substrate 35). After that, the thermal slug 46 is inserted into the space. In this case, solder is dotted on the upper surface of the thermal slug 46, and the thermal slug 46 is inserted into the space. Then, the thermal slug 46 and the lower ceramic substrate 35 are heated so as to be attached to each other. The solder is used to reduce bonding strength between the thermal slug 46 and the lower ceramic substrate 35, and thermal resistance on the boundary therebetween. If the lower ceramic substrate 35 is not formed of varistor material but general ceramic material such as alumina or LTCC, Ag is plated on a contact surface between the thermal slug 46 and the lower ceramic substrate 35 to improve the bonding property between the general ceramic and the thermal slug 46, and Ni or Ag (Ni or Sn) is then plated thereon to improve adhesion to solder. In addition, since the thermal slug 46 shown in FIG. 14 is a Cu slug, the thermal slug 46 has insufficient adhesion to the solder. Accordingly, the thermal slug 46 is plated with Ni or Ag (Ni or Sn) and then used.

[177] The upper ceramic substrate 40 is disposed on the lower ceramic substrate 35. The upper ceramic substrate 40 includes a cavity in a region corresponding to a region where the LED device 32 is mounted. A reflecting plate 44 is provided on the inner surface of the cavity formed in the upper ceramic substrate 40. A protrusion 44a, which is hung on the upper end of the upper ceramic substrate 40, is formed at the upper end of the reflecting plate 44. The upper ceramic substrate 40 is made of the same material as the lower ceramic substrate 35.

[178] A Cu slug is used as the thermal slug 46 in the sixth embodiment. A diamond slug having thermal conductivity of about 1000 W/mK may also be used as the thermal slug 46. The thermal conductivity of the diamond slug has a deviation depending on a technology for manufacturing the diamond slug.

[179] According to the sixth embodiment, since the substrate has high thermal conductivity, the thermal resistance is decreased between the LED device and the final portion from which heat is radiated. For this reason, the heat radiated from the LED device is more quickly radiated to the outside as compared to the first to fifth em- bodiments.

[180] In addition, it is possible to perform the eutectic bonding or flip chip bonding for bonding the LED device.

[181]

[182] (Seventh Embodiment)

[183] FIG. 15 is a cross-sectional view of an LED package according to a seventh embodiment of the present invention. When an LED package according to a seventh embodiment is compared with that according to the sixth embodiment, the seventh embodiment is different from the sixth embodiment in the structure of a lower ceramic substrate 35. Only the lower ceramic substrate 35 will be described in the following descriptions of the seventh embodiment. Other descriptions are the same as those in the above-mentioned sixth embodiment.

[184] According to a seventh embodiment, the lower ceramic substrate 35 is formed of two or more sheet layers. In FIG. 15, a first sheet layer 35a is laminated on a second sheet layer 35b. However, more sheet layers may be laminated, if necessary.

[185] The thermal conductivity (for example, in the range of 50 to 100 W/mK) of the first sheet layer 35a is higher than that of the second sheet layer 35b. The lower ceramic substrate 35 has high thermal conductivity (for example, in the range of 50 to 100 W/ mK). The lower ceramic substrate is made of a material in which glass for LTCC is added in one of AlN, BN, and BeO, to have the above-mentioned thermal conductivity. Alternatively, the lower ceramic substrate may be made of a material in which one of AlN, BN, and BeO is added in a ZnO-based varistor material. The process for manufacturing the lower ceramic substrate described in the sixth embodiment is used to manufacture the first sheet layer 35 a.

[186] It is preferable that the first sheet layer 35a be as thin as possible to ensure the surface flatness of the substrate that is required to quickly radiate heat from the LED device 32 and to perform eutectic bonding (or flip chip bonding). For example, in the case of a substrate having a size of 5 by 5 mm, it is preferable that the thickness of the first sheet layer 35a be in the range of 0.1 to 0.2 mm. It may be considered that the first sheet layer 35a becomes thinner. However, if the first sheet layer 35a is excessively thin, it is not possible to ensure the strength of the first sheet layer 35a and the flatness of the first sheet layer 35a during the sintering. According to the seventh embodiment, the first sheet layer 35a is thinner than the second sheet layer 35b such that heat is transferred more quickly to the thermal slug 46 of the second sheet layer 35b.

[187] A raw material is cast by using a doctor blade method and then laminated in accordance with a general process for manufacturing a varistor. As a result, it is possible to form the first sheet layer 35a. When the raw material is cast, a variation in thickness of the sheet can be controlled in the range of 0 to 1 D. Accordingly, it is possible to ensure the surface flatness of a substrate, which makes it possible to perform flip chip bonding or eutectic bonding. In particular, a material such as sapphire or SiC is used on the lower surface of the LED device 32. The thermal expansion coefficient of the material such as sapphire or SiC is similar to the thermal expansion coefficient of the first sheet layer 35a. Further, the thermal expansion coefficient of the first sheet layer 35a is 10% of that of metal. Therefore, it is very stable as compared to when the LED device is directly mounted on a metal as shown in FIG. 3.

[188] The thermal slug 46 passes through the central portion of the second sheet layer

35b. It is preferable that a Cu slug having thermal conductivity of about 250 W/mK is used as the thermal slug 46.

[189] The second sheet layer 35b may be made of alumina, quartz, calcium zirconate, forsterite, SiC, graphite, fusedsilica, mullite, cordierite, zirconia, beryllia, aluminum nitride, a varistor material, LTCC (low temperature co-fired ceramic), or the like.

[190] The method of attaching the thermal slug 46 in the sixth embodiment is used as that in the seventh embodiment. A Cu slug is used as the thermal slug 46 in the seventh embodiment. A diamond slug having thermal conductivity of about 1000 WVmK may also be used as the thermal slug 46. The thermal conductivity of the diamond slug has a deviation depending on a technology for manufacturing the diamond slug.

[191] In the seventh embodiment, the lower ceramic substrate 35 is formed of the first sheet layer 35a and the second sheet layer 35b so as to ensure the surface flatness of the substrate by using the first sheet layer 35a having high thermal conductivity, and so as to quickly radiate heat generated from the LED device 32 to the outside through the thermal slug 46 of the second sheet layer 35b.

[192] According to the seventh embodiment, the first sheet layer having high thermal conductivity is made of a material in which one of AlN, BN, and BeO is added in a varistor material. Further, the first sheet layer is formed in the substrate, and the thermal slug is inserted below the first sheet layer. For this reason, it is possible to decrease the thermal resistance between the LED device and the final portion from which heat is radiated. As a result, it is possible to quickly radiate the heat radiated from the LED device to the outside.

[193] In addition, it is possible to perform the eutectic bonding or flip chip bonding for bonding the LED device to the package.

[194]

[195] (Eighth Embodiment)

[196] FIG. 16 is a cross-sectional view of an electronic part package according to an eighth embodiment of the present invention.

[197] An eighth embodiment is a modification of the sixth and seventh embodiments. The eighth embodiment is different from the sixth and seventh embodiments in that a diamond slug 49 is provided between a mounting region of the LED device and a thermal slug 46.

[198] Pure diamond has thermal conductivity of about 2000 W/mK. The diamond slug 49 used in the eighth embodiment is made of industrial diamond. Impurities are added in the diamond slug 49 during the process for manufacturing the diamond slug 49, so that the diamond slug 49 is formed of CVD diamond having thermal conductivity of about 1000 W/mK.

[199] CVD diamond is poly crystalline diamond that is compounded at high temperature by using a heating source such as plasma and gas such as hydrogen or methane. If the diamond slug 49 is applied, the thermal conductivity increases. As a result, it is possible to radiate heat quicker to the outside as compared to other embodiments.

[200] Meanwhile, the diamond slug 49 has a thermal expansion coefficient of about 3 x

10 /⁰C. The thermal expansion coefficient of copper is 16 x 10 /⁰C. The thermal expansion coefficient of the LED device 32 is about 6 x 10 /⁰C. If a Cu slug is used instead of the diamond slug 49 in FIG. 16, there is a problem in that thermal expansion and contraction occur at the bonding interface of the LED device 32 and Cu slug due to the variation (difference) in temperature as described with reference to FIG. 3. However, the thermal conductivity of the diamond slug 49 is significantly higher than that of the Cu slug (the thermal conductivity of copper is about 350 W/mK), and the thermal expansion coefficient of the diamond slug 49 is similar to that of the LED device 32. For this reason, it is possible to prevent separation of the LED device 32 due to the variation (difference) in temperature.

[201] According to the sixth embodiment, glass for LTCC is added in expensive AlN,

BN, or BeO to use expensive AlN, BN, or BeO, so that the lower ceramic substrate has thermal conductivity in the range of 50 to 100 W/mK. According to the eighth embodiment, since inexpensive industrial diamond is used instead of expensive diamond, used as jewelry, it is possible to reduce the manufacturing cost. The thermal conductivity of the diamond slug 49 according to the eighth embodiment is much higher than the thermal conductivities of the heat transfer member 38, the first sheet layer 35a, and the thermal slug (Cu slug) 46 according to the above-mentioned embodiments. In addition, the thermal expansion coefficient of the diamond slug 49 according to the eighth embodiment is similar to that of the LED device 32. For this reason, the diamond slug 49 is the best means that has the most excellent heat radiation efficiency and can prevent the separation of the LED device.

[202] The diamond slug 49 according to the eighth embodiment is manufactured as follows: If gas such as hydrogen or methane is blown into a chamber (not shown) and plasma is then applied to the gas at high temperature for a predetermined time, a seed of a diamond slug is formed. The plasma is continuously applied to the gas at high temperature for a predetermined time until the seed of the diamond slug grows and has a desired thickness. Then, the upper and lower surfaces of the diamond slug having a desired thickness are machined by using a diamond tool, and the diamond slug is cut by using laser to have a desired size. For example, the diamond slug is cut to have a size of size of 2 x 2 x 0.5. The cut diamond slug is used as the diamond slug 49 according to the eighth embodiment. Since the variation in thickness of the diamond slug 49 is controlled to the desired range by using a general machining technology, it is possible to ensure the surface flatness of the substrate. The diamond slug 49, which has a thermal expansion coefficient similar to that of the LED device along with high thermal conductivity and can ensure the surface flatness, is disposed beneath the LED device 32, which makes it possible to resolve the above-mentioned problems.

[203] The manufacture of the diamond slug 49 is not limited to the above descriptions.

Any material can be used as the diamond slug 49, as long as a material has a desired thermal expansion coefficient and thermal conductivity even when a manufacturing process and the content of impurities are different.

[204] Meanwhile, when the thermal slug 46 according to the above-mentioned sixth and seventh embodiments is formed of a diamond slug, the diamond slug 49 manufactured as described above may be used as the thermal slug 46.

[205] A process for manufacturing the electronic part package according to the eighth embodiment will be described below. Since the mounting and wire bonding of the LED device 32 performed after the manufacture of the substrate has been well known to those skilled in the art, the descriptions thereof will be omitted. The lower ceramic substrate 35 is formed of two laminated substrates. A substrate having a via hole into which the diamond slug 49 is inserted is referred to as an intermediate substrate, and a substrate having a via hole into which the thermal slug 46 is inserted is referred to as a lower substrate. Alternatively, the lower ceramic substrate 35 may be formed of one substrate. In this case, a via hole may be formed at the center of the lower ceramic substrate 35, and the thermal slug 46 and diamond slug 49 are sequentially inserted into the via hole. In FIG. 16, the width of the thermal slug 46 is larger than that of the diamond slug 49. That is, a step is formed in the via hole that is formed in the lower ceramic substrate 35. The reason for this is that the thermal slug 46 is easily fitted to the via hole when the thermal slug 46 is inserted into the via hole. Meanwhile, the width of the thermal slug 46 may be equal to that of the diamond slug 49. However, when the width of the thermal slug 46 is easily from that of the diamond slug 49, it is possible to further improve the working efficiency.

[206] A plurality of ceramic sheets is laminated using a well-known process for manufacturing an LTCC, and a cavity is then formed in a portion of the sheets cor- responding to a mounting region of the LED device, so that the upper ceramic substrate 40 is manufactured.

[207] A plurality of ceramic sheets is laminated using a well-known process for manufacturing an LTCC, and a hole into which the diamond slug 49 is inserted is formed in the sheets by punching, so that the intermediate substrate is manufactured. Subsequently, pattern electrodes 34 and 36 are printed on the upper surface of the intermediate substrate so as to be separated from each other. Here, since the printing of the pattern electrodes 34 and 36 are well known to those skilled in the art, the descriptions thereof will be omitted.

[208] A plurality of ceramic sheets is laminated using a well-known process for manufacturing an LTCC, and a hole into which the thermal slug 46 is inserted is formed in the sheets by punching, so that the lower substrate is manufactured.

[209] After that, the intermediate substrate is laminated on the lower substrate, and the upper substrate is laminated on the intermediate substrate. Then, the laminated substrates are sintered.

[210] Subsequently, the thermal slug 46 is inserted into the hole from the lower surface of the lower substrate, and the diamond slug 49 is inserted into the hole from the upper surface of the intermediate substrate so as to come in contact with the thermal slug 46. In this case, a Ti, Pt, or Au layer or a Ti, Pt, or Ag layer is formed on each of the upper and lower surfaces of the diamond slug 49 by a plating and sputtering to improve the adhesion to the metal.

[211] The electronic part package according to the eighth embodiment is completed as described above.

[212] The thermal slug 46 and diamond slug 49, which have different thermal conductivities, have been used in the above-mentioned eighth embodiment. However, the diamond slug 49 may be inserted instead of the thermal slug 46. That is, the diamond slug may be used as the portions indicated by reference numerals 46 and 49 in FIG. 16.

[213] FIG. 17 is a table showing simulation results when the thermal conductivity of the

LED package (for example, the thermal conductivity of the substrate of the ceramic package) shown in FIG. 14 is set to 50 W/mK and 100 W/mK, and simulation results when the thermal conductivity of the first sheet layer 35b thereof is set to 50W/mK and lOOW/mK while the thermal conductivity of the second sheet layer 35b of the electronic part package shown in FIG. 15 is set to 25 W/mK. The power consumption of each of the LED devices was assumed to be 3 W, and the temperature of the air surrounding the package was assumed to be 25⁰C. The simulation was assumed to be performed under perfect heat equilibrium.

[214] Referring to FIG. 17, it is understood that a thermal resistance between the LED device and a metal PCB (not shown) of the structure shown in FIG. 14 is lower than that of the structure shown in FIG. 15. That is, the structure shown in FIG. 14 radiates heat quicker. However, a large amount of material, such as AlN, BN, or BeO, is required to form a substrate having the structure shown in FIG. 14 as compared to the structure shown in FIG. 15. Meanwhile, the material such as AlN, BN, or BeO is expensive and it is difficult to machine the material such as AlN, BN, or BeO. For this reason, it is preferable to adopt the structure shown in FIG. 15.

[215] The thermal conductivity of the package structure shown in FIG. 3 is higher than those of the package structure shown in FIGS. 14 and 15. When the simulation is performed while the thermal conductivity of the package shown in FIG. 3 is set to 25 WVmK and other conditions are the same as described above, a thermal resistance between the LED device and a metal PCB (not shown) is about 2.7O⁰CAV. However, according to the package structure shown in FIG. 14, thermal resistances between the LED device and the metal PCB (not shown) are about 4.73⁰CAV and 3.67⁰CAV, respectively. Further, according to the package structure shown in FIG. 15, thermal resistances between the LED device and a metal PCB (not shown) are about 5.5⁰CAV and 3.8⁰CAV, respectively.

[216] This means that the package structure shown in FIG. 3 more quickly can radiate heat as compared to the package structure shown in FIGS. 14 and 15. However, as described above, the package structure shown in FIG. 3 has problems in that the eutectic bonding is not appropriately performed or the LED device is separated due to difference in thermal expansion coefficient. Accordingly, it is not preferable to actually adopt the package structure shown in FIG. 3. For this reason, it is preferable to adopt the package structure shown in FIG. 14 or 15, which slightly has difference in thermal resistance but can ensure flatness and use a material having substantially the same thermal expansion coefficient as the LED device.

[217] FIG. 18 is an equivalent circuit diagram of the LED packages, which are arrayed, according to any one embodiment of the present invention.

[218] Seven LED devices Ll to L7 are provided between an input terminal IN and an output terminal OUT. Two LED devices Ll and L2, which are connected with each other in series, are referred to as a first group. Three LED devices L3, L4, and L5, which are connected with each other in series, are referred to as a second group. Two LED devices L6 and L7, which are connected with each other in series, are referred to as a third group. The groups are connected with each other in parallel. The LED devices Ll to L7 may not be connected with each other in parallel in the form of a group, and may be respectively connected with each other in parallel.

[219] One varistor VR is connected with the LED devices Ll to L7 of the first to third groups in parallel, between the input terminal IN and the output terminal OUT. A zener diode may be substituted for the varistor VR. [220] A noise removing circuit is provided between the output terminal OUT and a ground terminal GND. The noise removing circuit is composed of a capacitor C and a resistor R, which are connected with each other in series. Alternatively, the noise removing circuit may be composed of an inductor L and a resistor R, or may be composed of an inductor L and a capacitor C. Further, the noise removing circuit may be provided between the input terminal IN and the ground terminal GND. It is preferable that the resistor R be a resistor trimmed in the range of, for example, 10 to 200 Ω. Alternatively, the resistor R may be a fixed resistor having an optimum resistance.

[221] FIG. 19 is a plan view of the LED packages, which are arrayed on the basis of the equivalent circuit diagram shown in FIG. 18, according to any one embodiment of the present invention.

[222] In an array type LED package 100, seven regions divided in the form of a honeycomb are referred to as cells 110. Each of the cells 110 is an LED package. Each of the cells 110 includes an LED device 32. The LED device 32 provided in each of the cells 110 is primarily molded (coated) with a fluorescent substance and silicon. Epoxy may be used instead of silicon.

[223] One end of the varistor VR is connected to the input terminal 112 (V+) through a conductor 116. The other end of the varistor VR is connected to the output terminal 114 (V-) through the conductor 116.

[224] An annular inner dam 118 maintains the shape of each molded LED device 32 to have a desired shape (for example, a hemispheric shape or a flat dome shape).

[225] An annular outer dam 120 is formed around the arrayed LED devices 32. The outer dam 120 maintains the shape of the molded LED devices 32 to have a desired shape as a whole. Silicon or epoxy is used to mold all of the LED device 32 as a whole. The inner dam 118 and outer dam 120 may have an annular shape or polygonal ring shape. In FIG. 19, reference numeral 122, which is not described, indicates a molded portion.

[226] Reflecting plates are not shown in FIG. 19. However, reflecting plates may be provided around the LED device 32 in each of the cells 110. Alternatively, all of the LED devices 32 are assumed as one group, and reflecting plates may be provided around the group.

[227] Seven LED devices 32 are exemplified in FIG. 19. The number of the LED devices

32 may be increased or decreased. If the number of the LED devices 32 may be increased or decreased, the array of the LED devices 32 may be modified as shown in FIG. 20. That is, the array of the LED devices 32 may be modified in a shape that has one column and multiple rows as shown in FIG. 2OA, or in a shape that has multiple columns and multiple rows as shown in FIG. 2OB. Further, when the number of LED devices is five as shown in FIG. 2OC, the outer dam may be formed to have a circular shape. In addition, when the number of LED devices is seven as shown in FIG. 2OD, the outer dam may be formed to have a polygonal shape.

[228] The shape of an array type electronic part package is not important as long as the shape of the array type electronic part package is determined in consideration of an optical characteristic of the package.

[229] FIG. 21 is a cross-sectional view showing a portion where three LED devices

(reference numerals L3, L4, and L5 in FIG. 17) are arrayed in FIG. 19. A lower ceramic substrate 35 shown in FIG. 21 is exemplified as the lower ceramic substrate shown in FIG. 14. An upper ceramic substrate 40 shown in FIG. 21 is exemplified as the upper ceramic substrate shown in FIG. 14. In FIG. 21, the anode electrodes 34 are shown to be insulated from each other, and the cathode electrodes 36 are shown to be insulated from each other. However, the anode electrodes 34 are actually connected with each other, and the cathode electrodes 36 are actually connected with each other. Although a metal layer is not shown in FIG. 21, it is preferable that a metal layer be formed on the lower surface of the lower ceramic substrate 35 to improve adhesion and thermal conductivity between the lower ceramic substrate 35 and a metal plate 130.

[230] A metal plate 130 including a plurality of metal fins 132 is provided on the lower surface of the lower ceramic substrate 35. The metal plate 130 improves heat radiation efficiency. Further, when the plurality of metal fins 132 is formed in a wavy shape as shown in FIG. 22, the surface area of the metal fins 132 is increased. As a result, it is possible to further improve heat radiation efficiency.

[231] The maximum temperature of the LED device 32 is changed depending on the volume of the lower ceramic substrate 35, the length and thickness of the metal plate 130, the length and the number of the metal fins 132, and the like.

[232] A varistor VR, which prevents static electricity and surge, is embedded in the lower ceramic substrate 35 or is surface-mounted on the lower ceramic substrate 35. A noise removing circuit, which removes noise caused by the driving of the plurality of LED devices 32 arrayed on the upper surface of the lower ceramic substrate 35, is printed in the lower ceramic substrate 35. An RC connection type noise removing circuit is used as the noise removing circuit in FIG. 21. However, an LC or RL connection type noise removing circuit may be used as the noise removing circuit. In FIG. 21, reference characters hi, h2, and h3 indicate via holes in which conductive paste is filled, and reference characters Cl and C2 indicate electrode patterns formed on the different ceramic sheets. The electrode patterns Cl and C2 are arranged in a vertical direction. The two electrode patterns Cl and C2 form a capacitor. In FIG. 21, reference character R indicates a resistance pattern formed on a ceramic sheet different from the ceramic sheets on which the electrode patterns Cl and C2 are formed. The other end of the via hole h3 of which one end is connected to the resistance pattern R is connected to a ground pattern (not shown) formed on another ceramic sheet in the lower ceramic substrate 35.

[233] The electrode patterns Cl and C2 form a capacitor in the above description, but the electrode patterns Cl and C2 may form a varistor. In this case, only the material of the sheet is changed.

[234] As described above, circuits having desired functions are printed on ceramic sheets and laminated in the manufacturing process, and thus, components do not need to be separately mounted on a substrate. For this reason, it is possible to easily form a desired package and to reduce the size of the package.

[235] Each of the LED devices 32, which are arrayed, is primarily molded. The primarily molded portion is referred to as a molded portion 140. Although not shown in FIG. 21, the primarily molded plurality of LED devices 32 and the upper surface of the upper ceramic substrate 40 are secondarily molded to have the shape of a lens. In the primary molding, each of the LED devices 32 is molded with a fluorescent substance and silicon (or epoxy). Further, in the secondary molding, each of the LED devices 32 is molded with silicon or epoxy.

[236] In FIG. 21, the metal plate 130 and lower ceramic substrate 35 are bonded to each other so as to come in contact with each other. The heat radiated from the plurality of LED devices 32 is quickly radiated to the outside through the lower ceramic substrate 35 having high thermal conductivity and the metal plate 130. The metal plate 130 suppresses the deterioration of the LED device 32 due to the heat, so that the life span of a chip is increased. Further, the metal plate 130 suppresses the deterioration of a sealant such as resin or silicon, so that the reliability of a chip is improved.

[237] The array type electronic part package shown in FIG. 21 is manufactured by the following manufacturing processes.

[238] 1) A metal plate 130 is attached to a substrate, (referred to as a first process)

[239] 2) A plurality of LED devices 32 is arrayed, (referred to as a second process)

[240] 3) Wires 42 are bonded, (referred to as a third process)

[241] 4) The LED device 32 in each of cells is molded, (referred to as a fourth process)

[242] 5) All of the LED devices 32 of the cells are molded as a whole, (referred to as a fifth process)

[243] The schematic processes will be described in more detail below. The second through fifth processes are sequentially performed in this order, and the first process may then be performed for the last time.

[244]

[245] (First Process)

[246] First, a metal plate 130 and a substrate are manufactured.

[247] The metal plate 130 is manufactured by using a die or the like. [248] Further, the substrate is manufactured as described with reference to FIG. 14. A lower ceramic substrate 35 into which an upper ceramic substrate 40 and a thermal slug 46 are inserted is referred to as the substrate. The process for manufacturing the lower ceramic substrate 35 includes a process for printing inner circuit patterns (for example, patterns such as a inductor, resistor, varistor, capacitor, anode, and cathode) on ceramic sheets. When the process for printing the inner circuit patterns is performed, the RC connection type noise removing circuit shown in FIG. 18 is formed. That is, as shown in FIG. 23 A, electrode patterns used to form capacitors are formed on one surfaces of different ceramic sheets CS, respectively. Further, as shown in FIG. 23B, a resistance pattern R is formed on another ceramic sheet CS. Via holes (not shown) are formed in the electrode patterns Cl and C2 and resistance pattern R. In addition, the electrode patterns Cl and C2 and resistance pattern R may have shapes shown in FIGS. 23 A and 23B, or may also have other shapes.

[249] The metal plate 130 is attached on the lower surface of the substrate (that is, the lower surface of the lower ceramic substrate 35) manufactured as described above. Solder paste or dielectric paste is used to attach the metal plate 130 with the substrate. In this case, since metal cannot be directly bonded to ceramic, a process for forming a metal layer on the upper surface of the metal plate 130 and the lower surface of the lower ceramic substrate 35 is performed in advance. That is, after a metal layer is formed on the lower surface of the lower ceramic substrate 35 and a metal layer is formed on the upper surface of the metal plate 130, solder paste or dielectric paste is interposed between the contact surfaces of the metal layers coming in contact with each other and reflow is then performed. As a result, the metal plate 130 and the lower ceramic substrate 35 are firmly attached to each other. A well known technology may be used to form the metal layer.

[250]

[251] (Second Process)

[252] A eutectic bonding method, a bonding method using Ag paste, or a flip bonding method may be used as a method of bonding the LED devices 32 to the cathode electrodes 36. According to the eutectic bonding method, the lower surface of each LED device 32 and each cathode electrode 36 are eutectically bonded to each other under conditions that include the temperature in the range of about 250 to 35O⁰C, weight in the range of about 40 to 80g, and time in the range of about 5 to 30 ms. According to the bonding method using Ag paste, after Ag paste is applied to a portion to which the LED device 32 is attached, each LED device 32 is attached to the Ag paste portion of each cathode. Then, the LED devices and the cathodes are heated to the temperature in the range of about 120 to 18O⁰C. According to the flip bonding method, ball-shaped bumps are provided between the LED device 32 and the mounting region of the LED device of the lower ceramic substrate 35, and bonding is performed. When the flip bonding method is used, a wire bonding process, which is a succeeding process, does not need to be performed.

[253]

[254] (Third Process)

[255] The LED device 32 bonded to each of the cathode electrodes 36 is electrically connected to corresponding anode electrode 34 and cathode electrode 36 by using the wires 42. Further, since a series or parallel connection between electrodes 34 and 36 of one cell and electrodes 34 and 36 of an adjacent cell is well known to those skilled in the art, the descriptions thereof will be omitted.

[256]

[257] (Fourth Process)

[258] After the wire bonding is completed, each of the LED devices 32 is uniformly molded (coated) with a fluorescent substance and silicon (or epoxy). That is, after an inner dam 118 is formed around each of the LED devices 32, a fluorescent substance and silicon (or epoxy) is injected into the inner dam 118 by a dispenser. In this case, the weight of the fluorescent substance to be injected is in the range of about 3 to 30 wt%, and the concentration of the silicon or epoxy is about 2000 cps. When the molded portion 140 molded with the injected fluorescent substance and silicon (or epoxy) has a desired shape (for example, a hemispheric shape, a flat dome shape, or the like), the injection of the fluorescent substance and silicon (or epoxy) is stopped and the injected material is hardened at a temperature of 15O⁰C for three hours. Accordingly, the shape of the molded portion 140 is completed. The above-mentioned weight of the fluorescent substance, the concentration of the silicon or epoxy, and the hardening temperature and time are just examples. Accordingly, the above-mentioned conditions do not need to be necessarily satisfied, and the conditions may be changed if necessary.

[259]

[260] (Fifth Process)

[261] When the primary molding of the fourth process is completed, all of the LED devices 32 of the cells are molded by using the outer dam 24 as a whole.

[262] That is, the outer dam 120 is formed on the substrate, and silicon or epoxy having high viscosity is injected by a dispenser into the inner portion of the outer dam 120.

[263] When the molded portion 122 molded with the injected silicon or epoxy has a desired shape from which a desired orientation angle is obtained (for example, the shape of a lens), the injection of the silicon or epoxy is stopped and the injected material is hardened. Accordingly, the molded portion 122 having the shape of a lens is completed on the upper surface (that is, the entire surface) of the package. A method of molding the above-mentioned molded portion 122 is an injection molding method. A transfer molding method using powder may be used as the method of molding the molded portion 122.

[264] As described above, since the array type LED package is manufactured by using the first to fifth processes, it is possible to effectively radiate heat from the plurality of LED chips to the outside.

[265] Further, a semiconductor device that removes static electricity and surge and a circuit that removes noise are embedded in the substrate or are surface-mounted on the substrate. As a result, it is possible to reduce the size of the package to the maximum extent, and to provide an array type semiconductor package of which static electricity, surge, and noise are removed.

[266] In addition, since silicon or epoxy is coated on the upper surface of the substrate so as to have the shape of a lens, separate lenses or individual lens are not required.

[267] As described above, since it is possible to form an array type LED package shown in FIG. 21 by adopting the package according to any one of the first to eighth embodiments, it is apparently understood that an array type LED package falls within meets and bounds of the claims without specific disclosure in claims.

[268] The scope of the present invention is not limited to the above-mentioned embodiments, and all changes and modifications that fall within meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the claims.

[269]

[270]

Claims

[ 1 ] An electronic part package comprising: a light emitting device; a substrate having a mounting region of the light emitting device on which the light emitting device is mounted; and a heat radiating member buried below the mounting region of the light emitting device of the substrate so as to be separated from the mounting region of the light emitting device in a vertical direction, the heat radiating member being exposed to the lower surface of the substrate. [2] The electronic part package as set forth in claim 1, wherein a heat transfer member is formed between the mounting region of the light emitting device and the heat radiating member. [3] The electronic part package as set forth in claim 2, wherein the heat transfer member has higher thermal conductivity than that of the substrate. [4] The electronic part package as set forth in claim 3, wherein the heat transfer member is formed in a vertical direction so as to have a cross sectional size larger than or equal to that of the light emitting device. [5] The electronic part package as set forth in claim 3, wherein the heat transfer member is formed in a vertical direction so as to have a cross sectional size larger than the surface area of the light emitting device, and is divided into a plurality of regions, and one region, which has a diameter larger than or equal to the size of the light emitting device, of the plurality of regions is provided beneath the light emitting device. [6] The electronic part package as set forth in claim 3, wherein the heat transfer member is formed of a ceramic sheet layer. [7] The electronic part package as set forth in claim 3, wherein the heat transfer member is made of diamond. [8] The electronic part package as set forth in claim 7, wherein the heat radiating member is made of diamond. [9] The electronic part package as set forth in claim 1, wherein the substrate includes a cavity surrounding the mounting region of the light emitting device, a reflector is formed on the inner surface of the cavity, the reflector is connected to at least one of pattern electrodes formed on the substrate, and the pattern electrodes are electrically connected to the light emitting device. [10] The electronic part package as set forth in claim 9, wherein the pattern electrode to which the reflector is connected is separated from pattern electrodes formed in the mounting region of the light emitting device. [11] The electronic part package as set forth in claim 2, wherein the light emitting device is formed of an LED device. [12] The electronic part package as set forth in claim 1, further comprising: a varistor material layer formed on the substrate; first and second inner electrodes formed in the substrate, the first and second inner electrodes partially overlapping with each other with the varistor material layer interposed therebetween; and first and second outer electrodes provided in the substrate so as to be separated from each other, the first outer electrode being electrically connected to the first inner electrode and the second outer electrode being electrically connected to the second inner electrode.