Analysis of thermal impedance for conventional and beam lead IC chips

The thermal impedance of conventional and beam lead IC packages is evaluated from the partial differential equations, which govern the temperature and heat flow within the chip and substrate, and transmission line analogy. The mounting and the geometry dependance of the thermal impedance for various heat sink and chip sizes are presented for both beam lead and conventional IC packages. The variation of thermal impedance with the number of leads and the various Ceramic sizes is shown for the beam lead IC chip.The lumped and the distributed heat sources have been considered for the different mounting structures.