Issue link: https://iconnect007.uberflip.com/i/1295812
38 DESIGN007 MAGAZINE I OCTOBER 2020 the computing may be better off in a smaller technology node that would offer higher densities. By doing heterogeneous inte- gration, you can mix and match devices from different technolo- gies and maybe allow devices to be implemented in their more optimal process nodes, instead of having to be in the same single die. It gives a lot more flexibility for optimization. Even filtering devices can be integrated within the package for smaller form factors. The pack- age is becoming a miniature PCB. Johnson: Is that where things get different with the HIR compared to traditional multi- chip modules? It seems there is a much greater demand on the interconnect part of the tech- nology. Horner: HIR has bucketed multiple market spaces. They have 5G, computing, and high performance, and they're identifying every one of these, like automotive, aerospace, and dif- ferent market needs. The PCB traces that used to be 100-micron trace and spaces are shrink- ing further. On the multilayer PCB, the traces and spaces are about eight microns today. Happy Holden: Eight microns was the leading edge of people I worked with in Asia, and it's relatively high volume. They'll make 60–100 million of these 50-millimeter by 50-millimeter interposers on an 18- by 24-inch panel. It's very advanced printed circuit technology. Horner: That's almost the same as the cutting edge in package traces. Packaged substrates used to be 10-micron spaces and width, and the cutting edge is about eight microns right now. The silicon is smaller than one micron. The silicon interpos- ers that are available in the market right now, there is less than one micron, width, and space traces. They tend to be much older technology silicon material. The smaller the width and spacing for die-to-die connection, the more optimal widths and spaces. But it's good and optimal for lots of trace connections, like two or four gigabit-per-second types of frequency. But once you start going to higher data rates, you cannot maintain using silicon interposers. That's why people are moving more toward the organics, which have a lower loss, but then you're talking about much wider width and spacing traces. Effectively, people are approaching things both on the silicon side and on the packaging side, and trying to address die-to-die connection. Johnson: Looking into the HIR, I see reference to the organic interposer. Rita Horner Figure 1: Six application spaces undergirded by AI, VR and AR. (Source: ASE)