TRANSIENT THERMAL RESPONSE DUE TO PERIODIC HEATING ON A CONVECTIVELY COOLED SUBSTRATE

The increasing use of highly integrated circuits in portable electroni cs, which may operate for relatively short periods of time, has opened the possibility of utilizing heat storage to maintain device temperat ures 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-dimensiona l, axisymmetric, chip-on-substrate geometry is assumed with convective cooling on the bottom side. Exact solutions for the steady-periodic a nd complete transient responses are presented, peak temperature rise i s shown to depend on several geometric, thermal, and electrical parame ters. The results indicate that thermal resistance can be minimized wi th an appropriate choice of substrate thickness. Also, cycle periods o f tens of seconds can be achieved for typical electronic packages whil e retaining the benefits of periodic heating.