In-situ cure shrinkage measurement of die attach and underfill materials

Abstract

We present a robust method for measuring the cure shrinkage of dispensable organic films in-situ. Samples consist of dispensed organic material (e.g. die attach or underfill) sandwiched between a glass substrate and a silicon die. A Thermal Mechanical Analyzer (TMA) was used to accurately measure the displacement of the die during cure, and to control the temperature. An analytical model has been derived to disentangle the thermal shrinkage, and chemical cure shrinkage, which is verified by surface profile measurements (projection Moiré). We show that the measured displacement can be directly related to the cure shrinkage. To verify this methodology we have characterized a commercially available die attach material. The characterization yields a simultaneous measurement of the magnitude of cure shrinkage and the cure kinetics.