Stud Ball Bumping (SBB) Bonding Capillary

With continuous die size shrinkage and finer bond pad pitches of less than 60um, this solder bumping process is expected to be the future option for packaging technology miniaturization. For CSP flip chip application, solder bumping of wafer are done either by electroplating method to form the 63Sn-37Pb solder balls, and the other method is by gold (Au) ball bonds formed on the aluminum bond pad (Al) by a conventional wire bonder. Special designed capillary is needed to meet the different bond pad pitches. The general design rule on the desired mashed ball (MBD) given the bond pad opening still applies. However, since there is no looping, the capillary with 20 deg main taper angle (MTA) is one of the design features.

Single bump   Double bump  Capillary design

Figure 1: Pictures showing the Au bumping process on the Al pad



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