Issue link: https://iconnect007.uberflip.com/i/1483130
NOVEMBER 2022 I SMT007 MAGAZINE 77 world's energy gets directed toward data cen- ters because we're not as efficient as we need to be for managing these new workloads. Johnson: You talked about the constraints that are holding this computational development back—power among them. But what was inter- esting to me from a packaging point of view was that you also discussed the resurgence of a multichip module (MCM). e MCM was something we saw 20 to 25 years ago and then it faded away. What's bringing it back? McHerron: With scaling slowing, you're not getting as many transistors on a piece of silicon with each new generation as we did in the past. As computation workloads increase, you need more and more transistors. e system archi- tects will ask, "How can you get me more acres of silicon into my package to make this work?" We're already at the limits of reticle sizes, as I mentioned, the next generation of lithography for silicon, which will probably be online for manufacturing before the end of the decade; the reticle size will drop in half. Now, to get the hardware needed to enable the compute inten- sity required, you must put more silicon in each volume. You can't have it spread out across the board. It will drive your power requirements through the roof. So, the more you can bring these things together, the more silicon you can get in each volume. You're not getting it from transistor scaling like we used to, so it must come down to the packaging. Johnson: Compare the difference between a multichip module, what we're seeing in chiplets, and the heterogeneous integration type packaging. McHerron: In the past, MCMs were largely just putting more of the same chip into a package. e chiplet architectures, each one of these pieces of silicon, will now have its own func- tion and own personality. You must bring the package to interconnect all these different functions in a very efficient way, so you get good performance and energy efficiency. Johnson: Great. anks for the clarification on that, and thanks for your time. McHerron: Sure. SMT007