Thermal contact analysis of Flip-Chip package considering microscopic contacts of double-layer thermal interface materials

Flip-chip packaging technology is widely used in the field of electronic packaging. The thermal contact resistances (TCRs) of its double-layer thermal interface materials (TIMs) impact its thermal characteristics. In this paper, a flip-chip package thermal contact model is first constructed considering the internal rough contact interface of double-layer TIMs. Secondly, the effects of friction coefficient, pressure, elastic modulus of doublelayer TIMs, thermal conductivity of double-layer TIMs, interstitial medium, and convective heat transfer coefficient on the flip chip package's contact mechanics and thermal properties are analyzed. Finally, the influence of secondary thermal effects on contact mechanics and thermal properties is investigated. The results show that the friction coefficient, pressure, and elastic modulus of double-layer TIMs have a significant influence on the TCRs by changing the actual contact area, but the impact on the heat dissipation of the chip is limited, and the maximum temperature reduction does not exceed 10 K. However, the interstitial medium, convective heat transfer coefficient, and thermal conductivity of double-layer TIMs greatly influence the heat dissipation of the chip and maximum temperature by directly affecting heat transfer performance. Furthermore, secondary thermal effects have varying degrees of influence on contact stiffness, TCRs, and temperature distribution.