A thin and low thermal resistance aluminum nitride BGA package for high speed DSP devices

Abstract

Low thermal resistance and high TCT (temperature cycle test) reliability have been attained by thin AlN BGA package structure. High speed signal transmission for multimedia DSP (digital signal processor) has been analyzed by computer simulation. The package has 0.6 mm body thickness, which is 1/3 of ordinary ceramic packages. A low thermal resistance of 4.8 /spl deg/C/W has been attained without a heat sink and with no air cooling while mounted on a PWB having 4 conductive layers. Scattering parameters were measured up to 9 GHz and applied to 250 MHz clock signal simulation. No deterioration of signal waveforms was observed during the simulation. The effects of package thickness and package size have been discussed from the thermal resistance and TCT reliability point of view. Thicker and larger package size provided lower thermal resistance. The developed package thickness and size (35/spl times/35 mm) have been determined by taking into account the application field of mobile PCs (personal computers) and through simulation. The package thickness versus TCT reliability has been discussed, and then the TCT has been carried out under an assembled condition on a PWB, and MTTF of 1 k cycles has been derived.