A novel structure to realize crack-free plastic package during reflow soldering process-development of Chip Side-Support (CSS) package

A crack-free package that does not require moisture-proof packing can be realized by eliminating a die-pad and using the chip side support (CSS) method. The CSS packages of 0.45 mm thickness did not show any cracks at the reflow temperature of 240/spl deg/C for saturated moisture of 85% relative humidity. The design criteria of a crack-free package was established by calculating the shear stress and comparing it to the shear strength at the interface between the chip and the mold resin.