After we first noticed Clearwater final fall in Arizona, we observed it was sitting on a small PCB which was sitting on a bigger PCB. Across the silicon\/chiplets there was a light-weight coloured underfill with a darker one between the 2 PCBs. It appeared like an excessively advanced alternative that added value however the reply we obtained turned out to be something however.<\/p>\n Two PCBs for one CPU<\/strong><\/p>\n To the shock of nobody, you want a really prime quality substrate to mount a number of excessive finish chiplets, even with EMIB bridges. Clearwater Forest can also be a really huge CPU with a number of energy and information pins operating at excessive speeds so it wants a really huge PCB to slot in a really huge socket. A PCB that may do that wants prime quality supplies and many layers, each are trade synonyms for costly. That little PCB may be very excessive value little PCB.<\/p>\n The smaller PCB the silicon mounts to doesn\u2019t have enough area to place all of the pinouts wanted for the CPU to socket connection with out making the spacing far too slim to be sensible within the underlying socket. The answer? Unfold out the pins. How? With one other PCB clearly, which additionally lets you add extra passive elements too. Briefly the underside PCB is a glorified breakout field.<\/p>\n This brings us to the query of why do it this fashion, why not make that prime PCB a bit greater and keep away from the a number of extra packaging steps and attendant prices? Bear in mind once we talked about how these excessive finish substrate supplies had been costly, and I imply actually costly? It seems that making a single PCB from these supplies within the bigger measurement is considerably extra expensive than doing issues in a two tiered method. Assume shrubbery<\/a>.<\/p>\n So the lengthy and in need of this advanced sounding packaging resolution for Clearwater Forest will not be deeply technical engineering, it’s cash. Doing one huge PCB from costly supplies prices greater than two layers, one smaller and costly, one bigger and cheaper. Since it’s buried below a metallic warmth spreader, likelihood is nobody would ever discover, but when they do, there’s a straightforward clarification.S|A<\/strong><\/p>\n
![\"Intel](\"https:\/\/www.semiaccurate.com\/assets\/uploads\/2017\/11\/Intel_logo.png\"){kind=logo}
<\/a>Intel\u2019s Clearwater Forest CPU line has a quite distinctive function, it’s mounted to 2 PCBs. Semiaccurate puzzled why Intel used two substrates for this half and obtained a easy reply.<\/p>\n<\/a><\/p>\n
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