Wire Sweep Improvement Study for Fine Pitch Device

This paper presents the results of a wire sweep improvement study for fine pitch devices. With 44mum fine pitch device as test vehicle, on one hand, transfer mold process optimization with transfer profile was performed and wire sweep was controlled below 5%; on the other hand, new FFT (Flow Free Thin) mold technology with new granular compound was also evaluated to improve wire sweep and it can get excellent wire sweep control within 1.5%. With 40mum fine pitch device as test vehicle, the stiffer gold wire (2N type, 99% Au purity) was also tried for comparison with current gold wire (3N type, 99.9% Au purity) and the wire sweep data showed a large improvement on 2N wire. All the study experience will guide further study in ultra fine pitch (37mum or 35mum) and fine gold wire (0.7mils or 0.6mils).