The Influence of Several Design and Material Variables on the Propensity for Solder Joint Cracking

Encapsulated printed wiring board assemblies which are subjected to thermal cycling may be prone to the problem of solder joint cracking. In order to quantitatively assess the susceptibility and resulting reliability of these electronic packages, a series of tests were conducted. Several test units were designed to evaluate various material and design variables. Thermal cycling (-40°F to + 160°F) of these test Units with periodic visual and/or electrical examination of each solder joint resulted in a systematic comparison of several variables with regard to influence On solder joint cracking. Within the limitations of the test conditions, several recommendations can be made to advise designers of the design and production practices to minimize damage to solder joints