Effect of cure shrinkage of epoxy molding compound on warpage behavior of semiconductor package

Abstract

Cure shrinkage of the epoxy molding compound (EMC) for semiconductor package during molding process, was precisely measured using a fiber Bragg grating (FBG) sensor by measuring a Bragg wavelength (BW) shift. A dielectric sensor was simultaneously used to monitor the curing process of the EMC and define its gelation point. The relationship between internal strain development of the EMC and its degree of cure was investigated by correlating two measured values (The internal strain from the FBG sensor and the degree of cure from the dielectrometry). The viscoelastic properties of the EMC were also measured by a three-point bending stress relaxation test. Finally, the warpage of EMC-aluminum bi-layer strip was measured with digital image correlation (DIC) method and compared with the result from the finite element analysis. As a result, it was confirmed that the cure shrinkage of the EMC should be considered as an important factor in predicting warpage behavior of the semiconductor.