using new technology on old machines
Mark J. Blair
nf6x at nf6x.net
Mon Jun 15 17:17:06 CDT 2015
> On Jun 15, 2015, at 15:07 , Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
> One wonders why some manufacturer didn't realize there was money to be made
> in smaller cards (now less competition, but still enough demand to drive the
> prices up) and keep making them.
Because the chip fab equipment that was used to make the dies in the spaller parts has probably already been retired in favor for equipment suitable for smaller process geometries, and there's no point in making dies with storage capacity smaller than what fits in the minimum die size dictated by the pad ring necessary for the I/O. There actually is a lower limit to memory capacity, beyond which the cost cannot be reduced and the die cannot be shrunk. We call such chips "pad limited", as in the I/O pads dictate a minimum die size, and the die will cost almost exactly the same (save for minor yield variations) whether the middle is filled with gates or not.
I don't think that the hangups of a very few people justify ignoring the economics of semiconductor manufacturing.
Mark J. Blair, NF6X <nf6x at nf6x.net>
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