Investigation of graphite for radiation mitigation and thermal management in heat sink

Heat sink is widely amounted above the package substrate for heat distribution. Unfortunately, the resonance between heat sink and package substrate leads to the severe electromagnetic radiation, and results the product not satisfying the relevant EMI (electromagnetic interference) standards. It is a critical to simultaneously obtain the excellent radiation mitigation and desirable thermal management. In this paper, a combination of ring-shaped absorbing material and flat-shaped graphite is proposed. This paper investigates the effectiveness of graphite to mitigate radiation and optimize thermal performance based on a typical wire-bonded (WB) package. The experiment for EMI radiation is conducted in a semi-anechoic chamber. A good agreement between simulation and measurement is obtained.