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by Tuna-Fish
310 days ago
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Packaging used to be a huge portion of the industry, in the 80's when pin counts exploded and litho got cheaper it was usually the most expensive part of a chip. Today, it's cheaper mostly because of flip chips and Wafer Level Chip Scale Packaging (WLCSP). You build the bond pads as a normal litho step, and use a dielectric that's non-wettable between them. Then you can just use a mask to produce a grid of solder balls in the right places, drop the chip on them and put it in an oven. When the solder melts, the chip will self-align on it, so long as it's not too far off. It's uncanny to see it move. |
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