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Thermal cycling fatigue analysis of copper pillar-to-solder joint reliability

This paper evaluates two novel copper pin-head pillar interconnection structures with solder joints suitable for fine-pitch, low stand-off height interconnection for flip chip technology. Current flip chip interconnection requires underfill encapsulation to meet the requirements in thermal cycling fatigue test. An alternative to underfill encapsulation for improving solder joint reliability is to implement copper pillar-to-solder joint assembly. Such a copper pillar solder joint method is designed to meet the solder joint reliability requirements of 500 cycles suitable for telecom and portable electronic products. Parametric studies were conducted using finite element analysis to investigate the effects of different copper pillar-to-solder joint geometries on the solder fatigue performance.