Designing with thermal impedance

Thermal impedance and the main factors influencing it in plastic semiconductor packages are discussed. A test procedure is presented for measuring and quantifying the thermal characteristics of semiconductor packages. Using these test methods the thermal impedance of standard integrated circuit packages under pulsed and DC conditions were evaluated. Experimental evaluations of the thermal performance of small signal, medium-power, and high-power dual in-line (DIP) and multiwatt packages are presented as case examples. The effects of the thermal capacitance of the packages when dealing with low duty-cycle power dissipation are presented and evaluated in each of the example cases. >