The effect of clean and no-clean flux in enhancing the wettability of eutectic solder bump flip chip PBGA

Five different types of clean flux and no-clean flux, which are mainly used in flip chip die attach, have been analyzed in respect to the wettability of eutectic solder bump in flip chip PBGA. An experimental study is carried out to measure the spreading area of the eutectic solder bump processed with different types of flux. Various types of clean and no-clean flux are measured and placed on top of silicon die. The effect of the flux has been observed by measuring the spreading area of the eutectic solder bump processed with different types of clean and no-clean fluxes by using Leica Quin Colour (RGB) after the heat treatment. Comparative studies on clean and no-clean fluxes are therefore obtained. Clean flux has shown better wettability on the high lead solder pad proving it to be the optimum choice as also supported by the die pull results. Moreover, the fluxes are tested under thermal gravimetric analyzer (TGA) to observe the flux weight loss on the melting point of eutectic solder bump to correlate with the earlier results.