Study of underfill-to-soldermask delamination in flip-chip packages

Interfacial adhesion is critical to the reliability of flip-chip packages. A series of DOE studies were done to ensure and enhance the underfill-to-soldermask adhesion. It was found that vibration testing is most effective in simulating underfill-to-soldermask delamination. A rougher substrate soldermask surface and assembly with cleanable flux improves underfill-to-soldermask adhesion.