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Browse Prior Art Database

REPAIRABLE MULTI-CHIP MODULES

IP.com Disclosure Number: IPCOM000006174D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2001-Dec-11
Document File: 1 page(s) / 60K

Publishing Venue

Motorola

Related People

Lonnie Bernardoni: AUTHOR [+2]

Abstract

In today's consnmer electronic industry, reducing product size is a key initiative. A significant and ever increasing portion of the useable volume is needed for integrated circuits (ICs) and their protective packages. One commonly understood method of reducing the overall space needed for chip carriers is combining two or more KS onto a single substrate. For instance, a 80 I/O IC utilizing the latest in pad array solder attach technology takes about 0.60" of board surface.

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MOTOROLA INC. Technical Developments Volume 13 July 1991

REPAIRABLE MULTI-CHIP MODULES

By Lonnie Bernardoni and Ken Thompson

  In today's consnmer electronic industry, reducing product size is a key initiative. A significant and ever increasing portion of the useable volume is needed for integrated circuits (ICs) and their protective packages. One commonly understood method of reducing the overall space needed for chip carriers is combining two or more KS onto a single substrate. For instance, a 80 I/O IC utilizing the latest in pad array solder attach technology takes about 0.60" of board surface.

While three ICs totaling 128 I/OS have been combined on a substrate 0.70" sq. with only 56 solder joints. However, these multichip modules (MCM) create new yield problems at final test. For instance, a MCM

with three die that yield 95% each, rolls into a MCM yield of 86%. The high scrap cost makes MCMs

undesirable unless the MCMs can be repaired. If the failed 1C.s are removed and replaced, the scrap cost is the failed die only.

  Removing selective ICs without damaging the live 1C.s is not possible with most of today's high strength die attach adhesives. Excessive heat is required to degrade the bond sufficiently to mechanically pull the die off. Chemical solvents are another option but they are messy and too uncontrollable. One technique used to repair MCMS is to alter the packaging process flow.

Normal process flow follows the standard industry process and has the f...