Designing surface-mount technology for operational service life

In military and space applications, it is not unusual for the temperatures of solder joints and multilayer interconnection boards (MIBs) to cycle between -55° and +95°C. IBM has tested circuit card assemblies (CCA) and established the reliability of leadless chip carrier (LCC) components directly soldered to Kevlar epoxy MIBs, specifically solder joint life and plated-thru-hole (PTH) life, which are not adequately addressed by military specifications. The key is to match the coefficient of thermal expansion (CTE) of the MIB very closely to that of the LCC/SMT (surface mount technology). IBM´s laboratory test data provide the basis for (a) predicting field life from both thermal and vibration perspectives (b) determining whether this type of interconnection will last beyond its useful life (operational service life) requirement for military and space applications, and (c) determining specific material and process controls required to ensure a reliable product