Temperature Effect of Interfacial Fracture Toughness on Underfill for Pb-Free Flip Chip Packages

Abstract

In this study, the interfacial fracture toughness between passivation layer and underfill was investigated at elevated temperatures by performing conventional four-point bending test and finite element simulation. Since the board level reflow temperature for Pb-free flip chip packaging is reaching as high as 260 °C, the concern about delamination at the interfaces between underfill and its surrounding components becomes a more serious reliability issue. To estimate the interfacial strength, interfacial fracture toughness at a specific mixed mode loading condition is calculated. As temperature is increased, the interracial toughness was also increased up to the glass transition temperature. Beyond the glass transition temperature, however, interfacial fracture toughness is decreased.

Experimental and Modeling Studies of Thermal Barrier Coating Failure Under Isothermal Oxidation and Solid Particle Erosion

“…for plane strain[142].Under the hypothesis of SSY, a plastic zone (limited plasticity at the crack tip), containing microstructure defects such as dislocations and voids, are formed. The effect of dislocation shielding on the interface crack initiation and growth in metal/ceramic layered structures was studied by Mao et al[143].…”