The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 06, 1994
Filed:
Aug. 20, 1993
Barbara L Gutierrez, Austin, TX (US);
Cheng-Yuan Yu, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An easily reworkable circuit module is provided that allows unusable electronic components that have been encapsulated to be removed from a printed circuit board. A chip or MCM attached to a carrier using direct chip attach methods (DCA), such as C4 or SBC techniques that leave a space between the chip/MCM and carrier, due to the height of the solder balls, connection pads and the like. The present invention places a non-stick release coating on all surfaces intermediate of the chip and carrier. That is, the release coating of the present invention is placed by spraying, or the like between the chip and carrier to form a thin liquid film which inhibits the adhesion of a subsequently applied and cured rigid polymer encapsulant. Thus, when a chip or MCM tests as 'bad', rework is a relatively simple matter. The solder connections between the chip and carrier of the module are reflowed and the chip is lifted off. The solder reflow temperature will be below the melting point of the encapsulant, and since the encapsulant did not stick to the chip or carrier, it can be merely wiped away with a dry cloth.