Abstract: Thermal design is a very important part of chip packaging design, which directly affects the temperature and reliability of the chip during operation. The size parameters and physical properties of the packaging materials inside the chip have great influence on the heat dissipation of the chip. The thermal resistance of the chip or the junction temperature can be used to measure the heat dissipation performance. This paper studies the heat dissipation performance of some domestic FCBGA package by numerical simulation (Finite Volume Method), and analyzes the influence of factors such as material size, thermal conductivity of each layer in the CPU package and power density on the CPU temperature and thermal resistance. The research results show that, when the thermal conductivity of TIM1 is lower than  35 W/(m·K), the thermal conductivity and thickness of TIM1 have great influence on the heat dissipation of the CPU; the die area (power density) has great influence on the heat dissipation of the CPU, and the thickness of the die has little effect.

Key words: FCBGA, conductivity, interface material, die, power density