Browse Prior Art Database

CHIP CARRIER/PRINTED WIRING BOARD INTERFACE

IP.com Disclosure Number: IPCOM000005668D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-24
Document File: 3 page(s) / 104K

Publishing Venue

Motorola

Related People

Monty W. Bai: AUTHOR [+2]

Abstract

Attachment and interconnection of ceramic packages such as hermetic chip carriers to printed wiring boards (Figure 1) can result in exposure of the assemblied elements to load/stress distributions similar to those indicated in Figure 2 if the attachment/interconnections tend to closely couple the package to the PWB. Con- sequently, the reliability and durability of the package, attachments and interconnects can be severly compro- mised unless special measures are taken to minimize the levels or otherwise alleviate the effect of such loads and stresses. Use of such packages for military electronics applications often imposes particularly difficult problems in this regard due to requirements for rugged equipment capable of performing reliably during and after exposure to harsh dynamic and thermal environments.

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MOIOROLA Technical Developments Volume 7 October 1967

CHIP CARRIER/PRINTED WIRING BOARD INTERFACE

by Monty W. Bai and Larry Moore

   Attachment and interconnection of ceramic packages such as hermetic chip carriers to printed wiring boards (Figure 1) can result in exposure of the assemblied elements to load/stress distributions similar to those indicated in Figure 2 if the attachment/interconnections tend to closely couple the package to the PWB. Con- sequently, the reliability and durability of the package, attachments and interconnects can be severly compro- mised unless special measures are taken to minimize the levels or otherwise alleviate the effect of such loads and stresses. Use of such packages for military electronics applications often imposes particularly difficult problems in this regard due to requirements for rugged equipment capable of performing reliably during and after exposure to harsh dynamic and thermal environments.

   The chip carrier/printed wiring board interface design illustrated in Figures 3 and 4 provides features which either eliminate or significantly reduce such problems by simultaneously providing the means to positively at- tach and interconnect the ceramic package to the PWB while decoupling the package from both bending and inplane deflections of the PWB. This is accomplished as shown in Figures 3,4 and 5 by utilizing several discrete elastomeric spring-dampers to support the ceramic package within a flexible molded plastic "picture frame" which can be either bonded or attached via fasteners to the PWB. The material used for the spring-dampers can be varied along with their number and size in order to tune the system and provide the degree of support...