Browse Prior Art Database

Bulge Cap for a Semiconductor Substrate

IP.com Disclosure Number: IPCOM000041008D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Mendelson, R: AUTHOR [+2]

Abstract

A bulge cap design for semiconductor substrates which prevents liquid encapsulant from being pulled into the active device region and creating a reliability concern is reported.

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Bulge Cap for a Semiconductor Substrate

A bulge cap design for semiconductor substrates which prevents liquid encapsulant from being pulled into the active device region and creating a reliability concern is reported.

A conventional module cap has straight sides, as shown in Fig. 1. When a semiconductor substrate is inserted into a cap, standoff pads provide a mechanism for insuring that proper spacing is maintained between the top of the cap and the sub- strate. Module designs require a tight substrate to cap edge fit to contain an environmental back seal. When a liquid encapsulant is used as a back seal, capillary action can pull the excess sealant into the region of the active device, causing reliability concerns. Module reliability is especially reduced below an acceptable level if sufficient sealant is pulled into the region and forces its way under the active device, interfering with the chip's interconnection means.

By redesigning the module cap to include a bulge on the sidewalls, as shown in Fig. 2, the capillary force that pulls encapsulant into the active device region is eliminated. The cap is designed with an outward bulge which starts moving outwardly one-half the distance up the substrate sidewall. This allows a tight cap to substrate fit on the four edges while eliminating the driving force which pulls encapsulant into the region of the active device. The bulge design traps any encapsulant pulled into the interior of the cap and prevents it from r...