The thermal cycling reliability of copper pillar solder bump in flip chip via thermal compression bonding

摘要

In this paper, the thermal-mechanical reliability of flip chip on board (FCOB) with copper pillar solder joint is investigated. By increasing the temperature and time of the thermal compression bonding (TCB) process, the copper pillar solder joint with intermetallic compound (IMC) as the main body is obtained. Then the Cu pillar/Sn-Ag/Cu pad and Cu pillar/IMC/Cu pad joint structures are carried out the thermal cycling test separately. It is observed that the crack of the Sn-Ag solder joint caused by ductile fracture, which is leaded by fatigue and then extension through microvoids caused by creep. And the crack of IMC joint is mainly caused by the brittle fracture along the Cu6Sn5 and Cu3Sn phase interface. At the same time, two constitutive of viscoplasticity and elastic-plastic-creep and life prediction models are compared. The effect of underfill on the thermal-mechanical reliability of copper pillar solder joint is evaluated by comparing the underfills filled with different weight ratio filler particles.