Browse Prior Art Database

FORCE LIMITED SPRING WASHER

IP.com Disclosure Number: IPCOM000006977D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-13
Document File: 2 page(s) / 88K

Publishing Venue

Motorola

Related People

Authors:
Brian Webb

Abstract

In many applications of Single In-line Power Pack- ages a screw is inserted through a mounting hole in the heat sink of the package to hold it against an external heat sink. Over torqueing of the screw results in forcing the heat sink away from the plastic encapsulent. This in turn results in device failures from cracked die, wire bond failures and/or corrosion due to moisture ingress. This failure mode may be eliminated by the use of a spring washer which limits the amount of force applied to the device but at the same time insures intimate con- tact with the heat spreader for eff%zient heat dissipation. The novelty of this design includes the incorporation of a self limiting device in the spring washer design to insure foolproof assembly in semiconductor and other sensi- tive applications.