Development of low cost solder bump on LSI

The eutectic and the 95%-Pb high-temperature solder bumping process on 6 inch LSI wafer have been developed. Fountain method electroplating was used to deposit the solder for the cost effective and quality performance. Electrolyte used for the solder plating are targeting tin and lead components solder alloy. Sputtered seed film was used for the conduction of plating with good step-coverage and prevention of electrical damage. The deviation of bump height after reflow treatment is maintained below +/-10% for the pitch of 250 μm with the average bump height of 100 μm. To confirm the bump stability and reliability, we have evaluated the tensile strength and electrical connections of die and substrate initial and after thermal cycle test. The initial value of the tensile strength par die (12.7 mm sq. 180 I/O) was around 10 kg and the failure rate was 0% up to 300 cycle (0°C to 115°C) for high-temperature solder bump using alumina ceramic substrate with no resin underfill