Underfill Effects on BGA Drop, Bend, and Thermal Cycle Tests

摘要

Underfill typically is not used to encapsulate ball grid arrays (BGAs) or chip scale packages (CSPs) at the board level. However, the use for fine-pitch BGAs and CSPs in handheld devices, such as cell phones and PDAs, in automotive electronics, and in military applications, is increasing as the need for greater miniaturization and higher performance grows. In these applications, mechanical stresses can induce early failures. This article presents data showing the effects of BGA underfill encapsulation on solder joint performance under drop and bend tests, and thermal cycling. Relative solder joint reliability and failure modes are analyzed.