IBM, SUSS ramp C4NP pilot line

July 20, 2007 – IBM is now ramping pilot production of its first controlled collapse chip connection new process (C4NP) production line in East Fishkill, NY, just over a year after completing initial reliability testing for 300mm C4NP solder-bumped wafers.

The automated pilot line, supplied by SUSS MicroTec, is operating at 99.7% yield, and IBM is working to bring that up to about 99.9% yield, reports Barry Hochlowski, product manager, C4 bump and test for IBM, which is using C4NP packaging for its gaming systems products. A second C4NP line is being planned to increase production.

The line comprises mold-fill, inspection, and transfer steps. The solder-deposition technology places pre-patterned solder balls from a glass mold onto the surface of a chip, in a process that reportedly reduces costs and solder waste.

IBM ordered the C4NP high-volume bumping line in September 2005, after a year of development work with SUSS, which built a prototype fully automatic line, designed to accommodate 300 wafer starts/day, and installed it in East Fishkill. Initial tests in early 2006 focused on bumping 300mm wafers with SnCu and SnAg solders, using a 200µm pitch with 1.3 million bumps/wafer test vehicle.

The newest generation of C4NP bumping technology, which works with lead-free solder alloys, separates the underbump metallization (UBM) deposition from the solder bump deposition (unlike the old process integrating the two) so that it is more easily integrated with redistribution-layer metal, and may be done by the wafer fab. Costs are saved by working with pure solder and relatively simpler capital equipment compared to prior approaches, according to SUSS.

Additional reporting by Advanced Packaging.


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