Encapsulant for fatigue life enhancement of controlled-collapse chip connection (C4)

The characterization of a liquid silica-filled system for maximum processability of controlled-collapse chip connection (C4), or flip-chip connection, chips is described. Critical thermomechanical properties were studied to ensure that both ceramic module and card assembly conditions can be sustained. Both rheological properties and cure kinetics were optimized to provide enhanced flow and coverage of the C4s. Other key properties, such as shelf life, thermal stability, solvent and moisture resistance, and adhesion to various surfaces, are addressed.>