Cure behavior of a no flow underfill encapsulant

The curing reaction of a promising “no flow” flip chip underfill encapsulant is investigated by using a differential scanning calorimeter. It is found that the tested underfill can reach complete cure within 20 minutes at various cure temperatures. It is also shown that this “no flow” underfill could fully cure within one minute at 160°C after being heated at 220°C for one minute, demonstrating that this “no flow” underfill can be completely cured during the solder reflow cycle. The reaction order and the rate constant are determined to describe the curing progress. It is shown that the autocatalytic effect dominates the reaction kinetics.