Issue link: https://iconnect007.uberflip.com/i/1464168
20 DESIGN007 MAGAZINE I APRIL 2022 Torp: ere are some interconnect reliability features and functions that start to get involved in the whole design of the assembly itself, of what you're trying to connect. From a design standpoint, especially in the heterogeneous integration piece of it, it all starts with the design because you're now designing a system that will work together. It's not just designing the substrates or the boards. You're trying to marry it up into the shortest distance between the connections. You don't want to necessar- ily go through long transmission lines between the connections; you're trying to rack and stack things on top of each other. You're trying to minimize the losses within the transmission lines that are either in the board or the interposer layers. You want to minimize the number of connections between the dots. Matties: Dave, do you do rigid-flex with addi- tive? Torp: Yes. We look to put additive on poly- imide substrates, the backbone of a flexible circuit. While trying to get adhesion to some of the polyimides, we are doing some plasma prep work to rough it up just a little bit, so we get better bite into the polyimides. But we are deploying and employing the additive technol- ogy into the polyimides to get that finer line and space. Holden: Is the chemical a lot like the E Surface? Is it a nano technology? Torp: e chemical is a palladium base. It's very similar to the old E Surface technology. ere have been some twists and turns along the way to get better adhesion, but it's very similar. e patents for E Surface technology are owned by Additive Circuits Technologies and it's similar to what we were doing five to seven years ago. Now, it's just a matter of taking the technology and realizing it in a product, which was missing from the E Surface technology. With the additive technologies, that Z-dimension starts to become available to you. at wasn't available to designers working with subtractive methods. You can build a construct that follows a certain topography, and that fol- lows a certain geometry or a certain contour around a 3D geometrical design that is differ- ent than the traditional laminated flat structure that we're used to. ere are some military and defense companies who are interested in put- ting material into unusual configurations. Shaughnessy: What do you think it's going to take to get additive more into the mainstream? Torp: It's a niche, right now. So, as far as the additive into the mainstream, you need more manufacturers and fabricators capable of deploying the technology and putting it in. It's somewhat like what HDI was in the early days—nobody really wanted to share how they did it. You're all competing for a competitive advantage early on, and then you start to get it into this standardization mode. e standards committees will be vital in trying to get a set of standards, not only design guidelines, but a set of tolerances for manufac- turability of it before it really starts coming into the mainstream. But, if you look at some of the technology that goes into such things as the Apple Watch, and the number of interconnects and sensors inside a relatively complicated device, it's phenomenal the amount of integra- From a design standpoint, especially in the hetero- geneous integration piece of it, it all starts with the design because you're now designing a system that will work together.