Issue link: https://iconnect007.uberflip.com/i/836472
June 2017 • The PCB Design Magazine 21 All these kinds of applications are military aerospace that are using this for entirely dif- ferent reasons. They're not very cost sensitive because compared to the cost of what they're doing this is negligible. Again, reliability, per- formance and such are the main things that they're looking at and the fact that it costs a little more than a surface mount board or some- thing isn't a big deal for them. Matties: What sort of challenges does this place on designers? Herrera: Well, I think a lot of the questions that I get are what tools can we use to design this in? And I know Altium and some of the Mentor Graphics tools have embedded func- tionality built in that designers can use if they want these resistors to be embedded; the tool will help them embed them. Then there's the method that I'm more familiar with, which is the manual method, where you're sizing resis- tors based on the geometries and the power re- quirements or tolerance requirements, and then manually putting them in the artwork that way. But I think for designers, if they have the idea that they want to embed, it's reaching out to the tool provider that they're using and getting resources there or coming to us to get resources to figure out how to do it, and in addition to that we will also work with the board shops. If it's a board shop that's not familiar with processing our material, we'll get involved and help there, but for the most part we have a pret- ty big catalogue of board shops that are process- ing our material, that are familiar with it, and the support there is also great for the designer. For example, the board shop will adjust the art- work to compensate for processing factors. This is commonly done to hit controlled impedance targets and usually happens behind the scenes. The experienced board shops also understand how changes in geometries affect the finished resistor values. This becomes more critical as ge- ometries become less than 0.010" (0.254 mm). Andy Shaughnessy: It does seem like the tools have gotten better, though, because I remember there used to be no embedded design function- ality in any of the EDA tools for PCB. Brandler: I was at the last IPC conference on this and they moved on from passive to active. [See Figures 4, 5, 6 and 7.] That's the next big thing: embedding active components. And all the issues we had to deal with passives, like what happened with the lamination destroying some components? Well, it'll destroy the active component too or the interconnects anyway. There's a whole new world with actives, but we're still there. The passives are already estab- lished as being embedded. Then there's the in- troduction of highly precise printing and etch- ing using direct imaging, where you could do compensation and you don't have to laser trim to hold tolerances. As you eliminate tolerance as an issue then, what Manuel said becomes true, power starts becoming an issue when you get extreme miniaturization. Even though we normally don't think of any power being required, for things like ter- minating resistance down to a few milliwatts or whatever, it starts to add up. And then they get smaller and smaller and we have to deal with a temperature rise. This then becomes anoth- er constraint that is part of it. The other con- straint we have to deal with is ESD. ESD was a big deal particularly in the cellphone business when you're talking about human body model; can it pass 8,000 volts? Remember I said it was getting increasingly thinner because of the high frequency? Well, then ESD endurance becomes less and less. Now we have to design for ESD. At what voltage can you test these at and expect them to pass? And so that's been incorporated in our latest software. Our latest spreadsheet model now includes, besides power and tolerance normative value for the minimum size, we're also saying what's the minimum size for the voltage you're going to be testing on ESD. When we talk about direct, that means directly applying the ESD to the module. These are new challenges that we didn't really have a big problem with before, and because of this, it also changes the sheet resistivity, be- cause the lower the sheet resistivity the thicker it gets. Maybe it doesn't pass 8,000 volts at 50 ohms per square, but it does pass 8,000 volts at 40 ohms per square. What this has done for us is created a whole new range of products we have to add and we A DEEP LOOK INTO EMBEDDED TECHNOLOGY