Process for recovering bare semiconductor chips from plastic pac

Details Process for recovering bare semiconductor chips from plastic pac Process for recovering bare semiconductor chips from plastic pac

1994-08-26

1995-06-13

Chaudhuri, Olik

Fishing, trapping, and vermin destroying

437248, 437923, 437974, H01L 2166

Patent

active

054242541

ABSTRACT:
The method of the present invention is particularly directed to plastic packaged modules of the type wherein the contact zones of the chip are connected by wire-bonding to lead conductors and wherein the chip is molded in etch resistant resins. The opening method includes the steps of: a) polishing the module topside to eliminate the top part of the plastic encapsulating resin until the conductors of the lead frame are exposed; b) removing the lead frame; c) roughly polishing the module backside to eliminate the bottom part of the plastic encapsulating resin until the passive face of the silicon chip is exposed; d) immersing the resulting module in a hot fuming nitric acid bath raised to a temperature of about 120.degree. C. and for a time of about 8 minutes; and, e) immediately cooling the resulting module by blowing compressed ambient temperature air thereon to create a thermal shock whereby all the remaining parts of the plastic encapsulating resin are eliminated, leaving the desired bare silicon chip without damage.

REFERENCES:
Novus Technologies, Inc. Promotional Literature; (no date) 1423 San Rafael, Avenue Ne P.O. Box 53416.
ICOM Corporation Promotional Literature; No. Date 734 Slver Spur Rd., Ste. 201, Rolling Hills Estates, Calif. 90274
H. H. Blake, et al. "Technique for Observing Interfacial Filsm", IBM Technical Disclosure Bulletin, vol. 26, #1, pp. 648-650, Jul. 1983.
"Electronic Circuits-Preserving Technique for Decapsulating Plastic Packages" IBM Technical Disclosure Bulletin, vol. 30, #6, Nov. 1987.
"High Precision Polishing Technique to Open Electronic Components" vol. 33, #1A, pp. 305-306, Jun. 1990.

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