Assembly process Component failure mechanisms

Reliability of electronic assemblies is a complex subject.This chapter has touched on only one aspect of the problem understanding the primary failure mechanisms of printed circuit boards and the interconnects between these boards and the electronic components mounted on them. This approach provides the basis for analyzing the impact of design and materials choices and manufacturing processes on printed circuit assembly reliabihty. It also provides the foundation for developing accelerated testing schemes to determine reliability. It is hoped that the fundamental approach will enable the reader to apply this methodology to new problems not yet addressed in mainstream literature. 

Mechanically Induced Failures. PCBs may be mechanically loaded by test fixtures or processing equipment, when PCAs are loaded into card cages or fixtured into place with brackets, or when the assembly experiences mechanical shock or vibration in use. In general, once the PCA has been assembled, the interconnects to the components are the weak links in mechanical loading situations, not the boards themselves. 

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