A12X packaging

By: Maynard Handley (name99.delete@this.name99.org), November 12, 2018 7:24 pm
Room: Moderated Discussions
Some people here might find the A12X mounting rather interesting. (This is my take based on the photos, so correct me if I'm wrong.)

The standard A# mounting is PoP -- DRAM mounted directly on top of the SoC.
You can see a cross section here:
https://www.systemplus.fr/reverse-costing-reports/second-generation-of-tsmcs-integrated-fan-out-info-packaging-for-the-apple-a11-found-in-the-iphone-x/
and diagram here:
https://en.wikipedia.org/wiki/Package_on_package

But the X series has never done this. It's not clear why, though one hypothesis is heat dissipation.
So previous X series mounted the DRAMs as separate packages right close to the main SoC, like here:
https://d3nevzfk7ii3be.cloudfront.net/igi/WHKDR5ZU6SSQA3qa.huge

But if you look at the new iPad Pro, it looks like the DRAM is mounted on a substrate along with the A12X, ie they form a single package.
(It's a remarkably attractive looking package! Unlike anything I've ever seen before.)
This is interesting because it suggests something more exciting connecting the two than just standard PCB. One hypothesis (but this is only my guess) is that the substrate is something with lower capacitance than the usual organics of a PCB (so eg something like silicon). Using a lower capacitance substrate would reduce power and allow for higher frequency signals.

https://d3nevzfk7ii3be.cloudfront.net/igi/fCvUn2LuqBLcSLMR.huge

Longer term, of course, this might be Apple's first tentative steps in tighter packaging between the SoC and DRAM at the high end (requiring somewhat different techniques from at the iPhone end). One can fantasize that this leads to all sorts of interesting future ideas, from multiple compute chiplets to some form of high bandwidth memory to persistent on-package memory (Nantero, MRAM, or Micron's version of Optane)...

I do hope ChipWorks or someone similar shows us some details of this package and takes it apart for us.
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TopicPosted ByDate
A12X packagingMaynard Handley2018/11/12 07:24 PM
  A12X packagingAdrian2018/11/12 10:29 PM
    A12X packagingMaynard Handley2018/11/13 11:44 AM
      A12X packagingDoug S2018/11/13 11:52 AM
        A12X packagingMaynard Handley2018/11/13 01:34 PM
      A12X packagingAdrian2018/11/13 10:37 PM
        A12X packagingMaynard Handley2018/11/14 12:25 PM
  A12X packagingWes Felter2018/11/12 11:00 PM
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