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If this photo looks a bit ghostly that’s because
it is. We have no surviving photos of the TEL model TMC 4400-A, one
of the key systems that helped make today’s TEL into the powerhouse
that it is. This shot is of a made-in-America version of the Cobilt
division of Computervision, the CP-4400A. TEL held the manufacturing
rights to the CP-4400A in Japan.
But times were changing and Cobilt was about to exit the market. New
probing issues were emerging as wafer sizes drifted upwards and chip
complexity grew. Wafer bow was negligible in a two inch wafer but
too large for a vacuum to pull down in a five inch one. Automatic
vertical probe point control was essential. Full automation, while
needed for yield, nevertheless presented significant stumbling
blocks when differences in test time versus prober overhead time
were considered. In America, microprocessors and large memories
created tremendously long test times.
Because of these issues, Americans were reluctant to embrace fully
automatic systems while the Japanese needed them. TEL moved ahead
with what is probably the world’s first truly automatic prober,
built on the foundation of the old Cobilt 4400. But it was a
dramatically different machine.
The rest is history and TEL remains among the top wafer Prober
suppliers today.
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