Ultra-SB² is a fully automated solder bumping equipment with integrated flux printing, ball placement, 2D inspection and wafer level rework prior to solder reflow to enable optimum bump yield on wafer up to 100%. The machine is capable of handling wafer from cassette to cassette, and the integrated 2D inspection is not only inspecting the wafer after ball placement, but also including pre- and post-placement stencil inspection to maximize solder bumping process control.
The solder balls are placed onto UBM pads of the pre-fluxed wafer and being fixed into position. The process enables high accuracy ball mounting especially for micro solder balls and fine pitch layouts. The wafer mounted with solder balls will be inspected again for missing, misplaced and extra solder balls. The rejects are removed and replaced prior to solder reflow.