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Question I have is how much heat is generated by that power layer and as it is copper, shifting that behind the silicon - would we not see more thermal mass shi
by Zenst 5y ago
Question I have is how much heat is generated by that power layer and as it is copper, shifting that behind the silicon - would we not see more thermal mass shifted to the backend of the CPU and with a focus upon the top of the cpu for cooling solutions - how would that pan out? Would we also need some heat-sink upon the base of the CPU. Would we see extra heat shifted thru the silicon layer with this process?
One aspect that I've pondered that would save power would be having the memory closer to the CPU and all that usable real-estate for slots upon the reverse of the motherboard. Sure you would be looking at new case designs in a way or existing ones with new design considerations upon the mounting plate to have gaps to accommodate sockets upon the reverse of the motherboard PCB. That without having to compete with the CPU airspace for cooling and in effect using the motherboard to zone things, could work out well.
- baybal2 5y agoMost high end chips with high TDPs are already packaged upside down. You CPU, or 9 out of 10 recent phone/tablet SoCs are all upside down chips. https://en.m.wikipedia.org/wiki/Flip_chip https://en.m.wikipedia.org/wiki/Flip_chip So, it's actually going to be an improvement from the thermals side, especially with TSVs carrying heat from the other side to the heatsink.
- hinkley 5y agoThe power layer is going to leak less power to heat than the other layers, correct? So the power rails will work as heat spreaders, if not particularly great ones.
- ajaimk 5y agoArticle says this: 10% loss budget in Front side power delivery with a 7x improvement in the future => <2% of heat on bottom.
- formerly_proven 5y agoNot really, no. Pretty much all LSI chips (and even a lot of power / analog stuff these days) is flip chip, i.e. mounted metal-layer down (if you see a BGA or waferscale package, all of these are flip-chip). So the stackup looks like this (roughly to scale): Heatspreader TIM Silicon Silicon Silicon Silicon Silicon Silicon Silicon Silicon Silicon Active layer Metal layers Metal layers Passivation Solder bumps and glue Solder bumps and glue Solder bumps and glue Solder bumps and glue Substrate/interposer/PCB What this article proposes is to put metal layers on BOTH sides of the active layer, so you get more metal closer to it. That's what they mean by "powered from below". If you look at a chip today, they're all "powered from below" in the sense that the metal layers are "below" the active layer and power (and all signals) are fed in from "below" through the interposer.
- Zenst 5y agoThank you and appreciate the layer listing - most elegantly done.