Issue link: https://iconnect007.uberflip.com/i/1471044
JUNE 2022 I PCB007 MAGAZINE 13 We do a lot of what we call the button plat- ing. We put a image on the surface—essentially photoresist defining the pad and the via. And we go into our specially designed tank, where we alter the agitation, temperature, and solu- tion flow, so we can get that suppression on the surface and then get that wrapping up fill- ing. It's really done well. It's come a long way the last couple of years. Like I said, it's a big enabler when it comes to HDI. Feinberg: Have you seen any improvements in power supplies over the last 15 or 20 years? Carano: Sure, significant improvements. We've minimized and almost eliminated things like bipolar waves and we've eliminated things like loss. Everything is much improved. But I would like to give out some tips. Personally, when I troubleshoot at factories all over the world, one of the first things I do when some- one says they're having trouble getting good via fill consistently or good throwing power, aer analyzing the chemistry, is to say, "Take me to where your rectifier or your power sup- ply is connected to your plating cells." Here's a good example. At one shop I visited a year ago, all the rectifiers were located in the basement, and the plating cells were located on the floor above it. ey had to run a cable from the basement a couple hundred feet up to the plating cells. ey said, "What's wrong with that?" I disconnected it. I said, "Here, touch your hand to the cable." It was hot as hell because there was too much resistance. e rectifiers and the cable should be as close to the plating cells as possi- ble. Minimize that distance. Also, like I said, invest extra money in coaxial cables, which are a twisted pair. ey will give you much more efficient cur- rent flow. I don't care whether it's pulse plating, via field plating, or it's conven- tional through-hole. Keep the distance as short as possible, keep the anode connection and the cathode connec- tion as equal as you can. Use coaxial twisted pair of cables and you will minimize that cur- rent loss and something we call inductance, which when you run current through—espe- cially if you have pulse plating, you run cur- rent—you get electromotive force that wants to oppose that current. You don't want that. Shaughnessy: So, what are the biggest plating challenges right now for a typical American fabricator? Carano: e biggest challenge is that they're still running plating cells that were designed 15 years ago. ey have outmoded cabling, they don't really watch the anode-to-cathode ratio, and they don't use good quality anodes. As the technology changes, as they were asked to plate thicker boards and smaller holes, they really haven't changed the processes and the chemistry to go with it. at's where I see a lot of them falling down. Second, you must have process control. I'll say it over and over again. e heart of process control and quality is how to control your pro- cesses. When you go into higher-technology and more complex designs, your controls must be much tighter. You must learn how to live in a narrower window because those are the rules. Just think about it: As you get up there in age, your lifespan is narrower and you must take care of yourself in a different way. It means not drinking six gallons of whiskey every day. You must tighten things up and that includes the controls and the processes.