The study of novel metal/composite thermal interface materials for chip testing

Thermal interface materials (TIMs) which consist of metal foil and soft cushion are used in the process of chip processor platform validation (PPV) process, and some defects, such as the stains caused by debris peeled off from TIMs due to stress concentration, were found on the surface of the chips and they had an hazardous influence in the testing process. As well as that, the thermal resistance of TIMs is also a crucial issue that deserves to be further studied. To solve these problems, not only the metal layers in TIMs with less contamination are needed to be chosen, but also TIMs with higher thermal conductivity are needed to be developed. In this paper, Finite element method (FEM) was employed to evaluate the stress concentration area, where the debris were normally observed. And different kinds of composite were fabricated in a mould and tested in the PPV detection system. Simulation results showed that the stress concentration area is located at the contacted position between Al foil and chip, where the maximum stress and strain is 3.03×10⁷Pa and 9.379×10^-3 respectively. In addition, four different kinds of TIMs were fabricated and tested in the PPV system. It was found that the copper/ soft cushion is the potential TIMs.