Single Chip Bumping

The processes of bump deposition based on mechanical procedures together with their reliability data are summarised in this paper. The stud bumping of gold, palladium, and solder are described and also a novel bumping approach for fine pitch solder deposition down to 100 μm pitches using thermosonic bonding on a modified wedge-wedge bonding machine. This wedge bumping doesn't require a wire flame-off process step. Because of this no active atmosphere is necessary. The minimum pad diameter which can be bumped using the solder wedge bumping is 50 μm up to now and can be reduced by further optimisations. The thermosonic solder wedge bumping process is highly reproducible and therefore well-suited for different flip chip soldering applications.