WO2001078113A1

WO2001078113A1 - Desiccant containing product carrier

Info

Publication number: WO2001078113A1
Application number: PCT/US2000/030730
Authority: WO
Inventors: Anthony B. Morrow
Original assignee: Advanced Micro Devices, Inc.
Priority date: 2000-04-05
Filing date: 2000-11-08
Publication date: 2001-10-18
Also published as: US20020185409A1; TW480559B

Abstract

Disclosed is a product carrier having a desiccant incorporated therein and a method for making the same. The inventive carrier reduces the number of steps required to package a semiconductor device.

Description

DESICCANT CONTAINING PRODUCT CARRIER

TECHNICAL FIELD

The present invention relates to a product carrier that has a desiccant incorporated therein. The present invention is particularly applicable in reducing the steps required to package a semiconductor device.

BACKGROUND ART

The world of shipping and handling is a hostile one in which product can encounter stress from moisture, temperature changes, and rough handling. Carefully designed packaging methodologies that ensure the preservation of product quality from the factory floor to the customer are required.

Some IC packages are susceptible to moisture induced damage. The risk of this is highest when plastic encapsulation materials are used, as plastic is naturally permeable to moisture. The moisture in the package will increase or decrease to reach the Relative Humidity (RH) of the surrounding environment. Therefore, controlling the moisture level in the package body is critical to reducing the risk of moisture-induced damage. Such damage may include delamination between the die and the plastic encapsulation material, which may result in open connections due to broken wirebonds. Package cracking may also occur when the components are exposed to the high temperatures and steep temperature gradients used in reflow board assembly techniques. Moisture in the package rapidly heats and vaporizes and, if there is sufficient steam due to the moisture in the package having reached a critical level, it will fracture the package to escape. This phenomenon is known as the "popcorn effect."

Thus, plastic semiconductor devices are susceptible to moisture due to the permeable nature of their plastic components. It is well known that integrated circuits which are contaminated by high levels of moisture may not be useful. Mechanical failure of such contaminated integrated circuits often leads to the subsequent electrical failure of the device which contains the integrated circuit due to thermal and mechanical stresses. Accordingly, exposure of integrated circuits to moisture should be limited.

This concern about limiting the exposure of integrated circuits to moisture has been addressed in the design of shipping packaging for integrated circuits. Currently the preferred method to form a packaging system for integrated circuits includes baking the integrated circuit devices until dry, placing them into a water and humidity proof packaging bag which contains desiccant packets and a humidity indicator card, sealing the bag immediately, and then shipping the device to the customer in these packaging bags. Once it is determined that a product is moisture sensitive, the product is typically dry packed for storage and shipment. This is done for all types of product carrier (e.g., tubes, trays, reels, etc.). Dry packing protects product from environmental moisture by maintaining the interior of the dry pack bag at (less than or equal to) 20 percent RH. Included in the dry pack bag are a prescribed number of desiccant pouches. The desiccant pouches greatly reduce the presence of moisture.

SUMMARY OF THE INVENTION

There exists a need for an efficient cost-effective carrier for a semiconductor device which eliminates unnecessary product packaging steps.

There is also a need for a method for manufacturing such a carrier in an efficient, cost-effective manner. According to one aspect of the invention, a carrier for a semiconductor device is provided. The carrier includes a material containing desiccant particles embedded therein and a holding region for the semiconductor device.

Another aspect of the present invention provides a method for manufacturing such a semiconductor carrier. The method includes the steps of mixing a desiccant with molten plastic and molding the mixture into a product carrier.

Other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The invention is capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent like elements throughout.

Fig. 1 illustrates an embodiment of the present invention. Fig. 2 illustrates a flow chart for practicing a method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention is illustrated in Fig. 1, wherein the product carrier is a fray 20 formed from a material, e.g., plastic. It will be appreciated that other materials suitable for forming relatively thin, sturdy structures can be used to form tray 20. Exemplary materials include, for example, conductive thermoplastic, non-conductive and insulated plastic, antistatically coated PVC, antistatically coated polysulfone (to provide protection from ESD damage and to eliminate the potential for low leakage between component leads), conductive carbon-filled polypropylene, and black dissipative BPI-10 plastic. In certain embodiments, the carrier material can withstand temperatures up to about 40°C to about 60°C, for example, temperatures of -125°C to 150°C. The material can also include a carbon-based material or be antistatically coated to provide ESD protection.

With continued reference to Fig. 1. desiccant particles 25 are embedded within tray 20. A preferred desiccant is montmorillonite (bentonite) clay. Tray 20 includes a notched corner 25, a flat or open bottom 27, two sets of opposing vertical sides 23a, 23b, and an open top 29. Together, the flat bottom and two sets of opposing vertical sides foπn a holding region in which a semiconductor device may be placed. Multiple frays of product can be stacked for shipment with an additional tray serving as a cover. All devices can be uniformly oriented so pin one is aligned with the notched corner 25 of tray 20.

Though the embodiment depicted in Fig. 1 comprises a single material, it should be emphasized that the product carrier of the present invention may comprise one or more materials and/or may comprise one or more layers of material. Further, the inventive product carriers may comprise a recycled material, such as about 5% to 30% recycled materials

In this exemplary embodiment, the product carrier is a fray. However, given the guidance and objectives disclosed herein, the particular product carrier, e.g., tube, fray, reel, and jewel box, can be readily selected and optimized based on a particular semiconductor device to achieve the goals of the present invention.

Moreover, one having ordinary skill in the art will appreciate that the present invention is not limited to product carriers for any particular IC package style. Rather, the product carriers of the present invention may be configured to accommodate, for example, Pin Grid Arrays (PGAs), ceramic flat packs, non-quad flat packs, quad fiat packs, and Dual-In-Line packages. In the embodiment illustrated in Fig. 1, the tray is configured to accommodate multiple semiconductor devices. However, the inventive product carrier may be configured to accommodate a single device and/or product carriers may be configured to accommodate a plurality of devices, each of which is already being held in a carrier.

The inventive product carriers are uniformly sized, in compliance with standard JEDEC outlines. The inventive product carriers are also sized to ensure that there is no excessive movement of product in the tube during shipping and handling. This protects the mechanical integrity of the package and, if present, leads; it also ensures an unimpaired dispensing of product for manufacturing operations.

For shipment, a stack of trays, for example, six frays, can be secured with straps; five containing parts and the sixth serving as a cover. Bound trays may then be loaded into an antistatic bubble pack bag, for extra cushioning protection, and then packed in a tray box for shipment. Because a desiccant is incorporated directly into the product carrier, it is unnecessary to include separate desiccant packets in the packaging bag.

Fig. 2 is a flow diagram illustrating the method for forming a product carrier in accordance with an embodiment of the present invention. Referring to Fig. 2 at step 200, desiccant particles, such as montmorillonite (bentonite) clay, are mixed with molten plastic. At step 210, the molten plastic with desiccant particles mixed therein is molded into the product carrier, as with conventional techniques. One of ordinary skill in the art will appreciate that the amount of desiccant mixed with the molten plastic will be sufficient to greatly reduce the presence of moisture in a dry pack bag (i.e., moisture barrier bag). For example, the amount of desiccant mixed with the molten plastic can be optimized such that there are about 32 grams of clay to about 64 grams of clay per dry pack bag. Alternatively, the amount of desiccant mixed with the molten plastic can be optimized such that the environment in the bag is maintained at no greater than 20 percent RH, thus protecting the devices during shipment and storage for at least 12 months. If this 12-month shelf life is exceeded, the devices need to be dry baked again only if the RH in the bag has exceeded 30 percent, as evidenced by a humidity indicator card.

Upon determination that a product is moisture sensitive , the product is dry packed for storage and shipment. This is done regardless of the type of product carrier (e.g., tubes, frays, reels, etc.). The first step in the dry pack process is to remove any moisture buildup in the package by baking the finished product for 5 to 15.5 hours, depending on the package type, at 125°C +/- 5°C. While baking, the product is contained in the product carriers (provided the carrier is made of material that can withstand the high temperature) or aluminum trays or tubes. Within 50 hours after baking, the product is sealed in a dry pack bag under a partial vacuum.

An exemplary dry pack bag (i.e., moisture barrier bag) is designed with three layers. The inner layer is a low-density polyethylene, which has a static-dissipative coating. A second layer is 400 angstroms aluminum metallized to 92-guage polyester. The third layer is 400 angstrom aluminum metallized to 92-guage polyester, which has a static-dissipative coating. ESD protection is provided by the inner layer of antistatic polyethylene and the second layer of aluminum metallized polyester. The bag is sealed using an impulse heat sealer at a seal time of about 1.0 to about 1.5 seconds; and a seal pressure of about 40 to about 50 psi; and a temperature range of about 191 to about 232°C.

Included in each dry pack bag is a card that has humidity sensitive elements which turn from blue to pink whenever the specific RH level is exceeded. Labels may also be applied to the outside of the dry pack bag. For example, a standard product label, which identifies the contents by manufacturing lot number, product part number, and the product date code(s) and quantity per date code. Also, a dry pack caution label, which identifies the date the bag was sealed, the dry pack expiration date (which is 12 months later)), as well as product handling guidelines. A small moisture-sensitivity caution label may also be applied to the outside of the box in which the dry packed parts are packed.

Described has been an apparatus and method for manufacturing an apparatus that is a carrier for semiconductor devices. An advantage of the invention is that it can easily be implemented and is both efficient and cost-effective in reducing the number of steps required to package and ship a semiconductor device. Another advantage of the invention is that it is readily fabricated and customized to various semiconductor devices. In this disclosure, there is shown and described only certain preferred embodiments of the invention, but, as aforementioned, it is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.

Claims

WHAT IS CLAIMED:

1. A carrier for a semiconductor device, the carrier comprising: a material containing a desiccant embedded therein; and a holding region for the semiconductor device.

2. The carrier of claim 1, wherein the desiccant is montmorillonite (bentonite) clay.

3. The carrier of claim 1, wherein the material can withstand temperatures from about -125°C to about 150°C.

4. The carrier of claim 1, comprising: at least two layers of material.

5. The carrier of claim 1, wherein the material comprises about 5% to about 30% recycled materials.

6. The carrier of claim 1, wherein the carrier is selected from the group consisting of a tube, a tray, a reel, and a jewel box.

7. The carrier of claim 1, wherein the carrier is configured to accommodate a single semiconductor device.

8. A method for manufacturing a carrier for a semiconductor device, the method comprising the steps of: mixing a desiccant with molten plastic; molding the mixture into a product carrier, loading a device into the product carrier; and dry packing the loaded product carrier in a bag.

9. The method of claim 8, comprising: mixing sufficient desiccant with the molten plastic such that the dry packed product carrier comprises from about 32 grams of desiccant to about 64 grams of desiccant.

10. The method of claim 8, comprising: mixing sufficient desiccant with the molten plastic such that an environment within the dry packed bag is maintained at no greater than about 20 percent relative humidity for about 12 months.

11. The method of claim 8, comprising: molding the product carrier into a form selected from the group consisting of a tube, a tray, a reel and a jewel box.

12. The method of claim 8, comprising: molding the product carrier into a form configured for holding one semiconductor device.

13. The method of claim 8, comprising: molding the product carrier into a form configured for holding a plurality of semiconductor devices.

14. The method of claim 8, further comprising the step of: including a card comprising a humidity sensitive element in the dry packed bag.

15. The method of claim 8, further comprising: labeling an outside of the dry pack bag; packing the dry pack bag in a box; and labeling an outside of the box with a moisture-sensitivity caution label.