Effect of P on interfacial reaction and shear strength for FCBGA packaging with indium thermal interface materials under isothermal aging

Metal indium exhibits significant application value in high-power electronic packaging due to its excellent thermal conductivity (82 W/(m·K)) and ductility. However, under high-temperature service conditions, the excessive growth of intermetallic compounds (IMCs) at the interface seriously affects the reliability of the interface. In this study, we conducted an in-depth analysis of the In/Au/Ni(P)/Cu system and found that the formation activation energies of the (Ni,Au) 28 In 72 phase and the Ni 3 P phase were 96.365 kJ/mol and 32.13 kJ/mol, respectively. Experimental results show that, compared with the traditional system, the Ni(P) layer reduces the average thickness of the (Ni,Au) 28 In 72 layer by 50 % after aging treatment at 150 °C for 500 h. It achieves this by increasing the atomic diffusion barrier, thus confirming its excellent diffusion barrier performance. Mechanical test data further demonstrate that the shear strength of the system is 21.3 % higher than that of the traditional system. This study has confirmed that the Ni(P) layer can significantly improve the long-term reliability of indium thermal interface materials (TIMs) in flip chip ball grid array (FCBGA) packaging under high-temperature service conditions, and has verified its industrial feasibility through the existing production lines.