Heat spreader impact on electrical performances of a 4-layer PBGA package

Electrical simulations are performed for a 4-layer 388-ball PBGA package to investigate the heat spreader (HS) impact on electrical performances at high frequencies. The results show that a heat spreader, no matter floating or grounded, can help to minimize both the self and mutual inductances in a relatively low frequency range. However, a grounded HS can help to maximize the signal transmission efficiency due to low losses. In addition, grounding the HS mitigates the electromagnetic interference (EMI) issues that may occur in a floating HS case at high frequencies and at the same time helps to push the self-resonant frequency of the package to a higher value, which effectively widens the bandwidth of the package.