Transient thermal response due to periodic heating on a convectively cooled substrate

The increasing use of highly integrated circuits in portable electronics, which may operate for relatively short periods of time, has opened the possibility of utilizing heat storage to maintain device temperatures below reliability limits. The present study considers a strategy in which the power dissipation of a device is periodically reduced and increased in order to decrease its peak temperature. A two-dimensional, axisymmetric, chip-on-substrate geometry is assumed with convective cooling on the bottom side. Exact solutions for the steady-periodic and complete transient responses are presented. Peak temperature rise is shown to depend on several geometric, thermal, and electrical parameters. The results indicate that thermal resistance can be minimized with an appropriate choice of substrate thickness. Also, cycle periods of tens of seconds can be achieved for typical electronic packages while retaining the benefits of periodic heating.