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PCBD-Apr2017

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18 The PCB Design Magazine • April 2017 FABRICATORS SPEAK OUT ON HIGH-SPEED MATERIALS Partida: For the military industry, they're not going to use anything that hasn't been approved and it's official. There is a required amount of time they have to continue to produce it, so the laminate suppliers want to make sure that it's done. When you're dealing with the end custom- er, especially military, it has to be an established product. We're fortunate enough that for many years we tested the material with different laminate suppliers before it even had a part number. So they paid us to laminate the boards and we're getting paid to learn how to use the material, and then we get all the feedback on how well it performs. We've been fortunate as a company to benefit from this relationship for about six or eight years. Menning: On the flex side, most of our mate- rials are coming from people like DuPont or Panasonic and we kind of operate the same way. If we've got a customer need that doesn't fit into the current available material set, we'll work closely with those suppliers on new ma - terials and do evaluation runs for customers to help them get comfortable with these ma- terials that are new to the world. From our end, a lot of the requests are surrounding not so much high-speed but high-temperature. Traditional acrylic adhesives typically would work up to 150°C, and if we get customers like downhole drilling applications, where it›s really high-temperature applications, it pushes into new material sets where traditional acrylic adhesives would not survive. Those high- temp materials also are of value to us in our flex heater business and we also can combine flex heaters with flexible printed circuits for applications where they want a localized heat source and they also want to have high- temperature durability in the remainder of the flex circuit. Matties: With the amount of new materials com- ing into the marketplace, how difficult is it to get a customer to try something? So many of them have specified their brands and stick with them. Are you finding they're motivated to change? Partida: I think a lot of times when they're stuck in a design where the existing materials are not working for them, whether it's registration, di- mensional, or they can get the right dielectric thickness, then they're open to it. Again, as I said earlier, the RF community is the most open- minded to suggestions and working with fabricators that I've ever seen in the electronics industry, and I've been in it for 30 years. It's fun to walk into a room with literally 10 PhDs and they ask you good questions. They're very enthusiastic about working together and trying different methods to solve a problem. They're open to new materials, but when they have a product that's been used in a particular construction or material selection and they're just making small modifications to it, they will not deviate from it because they know it works. Matties: They know it works and they're not going to be driven by a few dollars on pricing when they know it works. Partida: Right, I would say that's a very accu- rate way of stating that, yes. Goldman: You both talked about pre-treating something like a PTFE, and I was wondering, what you do to stabilize that or how do you have to pre- treat those very smooth surface materials? Partida: In most cases, plasma will work with the hydrogen cycle at the end and then a purge. This will make the surface sticky so the electroless will attach to it. Sodium etch will have the same effect. Even soldermask and legend, it's so slippery a surface you can put soldermask down and tape test it and it will peel every bit of it off during a tape test. You have to activate the surface and (we like to use real technical terms in fabrication) to make the surface sticky and then the soldermask will adhere to it. Menning: Yes, we do the same on the flex side. The plasma treatments are typically what we would use for activating the surface. The trick, Joe Menning

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