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Nolan Johnson dives into test and inspection with Bob Neves of Microtek Laboratories China. From his perspective running a test lab, Neves shares his view on the current issues for contract manufacturers regarding test and inspection. Over the course of this conversation, Neves discusses the effect of the current supply chain on testing practices, factory automation, the collection an analysis of data, and more. For all the automation and data collection possible, Neves points out, it still comes back to the people.
Nolan Johnson: Bob, from your perspective, what are the current issues for assembly, as well as fabs as it applies to assembly.
Bob Neves: With fabs, it continues to be between via reliability and the long-term isolation, CAF, or electrochemical migration. Those are the things that never go away. The two primary functions of the printed circuit board are to move current where you want it to go and keep it from where you don’t. Those are the two primary functions and tend to be in people’s focus.
Microvia technology seems to be changing. Everybody thought microvias were bulletproof, but as microvias structures have become more aggressive and with multiple layers and interconnecting geometries, things started to happen. They’re not as bulletproof as they used to be when they were just one or two layers. There’s a lot of effort trying to understand what’s going on with microvia issues and CAFs; it’s just a long-term thing. They’re the people who need long-term reliability. They’re really concerned about it—those in automotive, communications, space—they’re all very interested in long-term capital liability.
I’ve got over 30 humidity chambers at Microtek China with a team of about 12 people and that’s all they do; their entire occupation is just doing CAF for customers. The expectations are getting longer and the voltages are getting higher. People are pushing boards more and expecting more from them. This whole move to electrical motivation—whether that’s, cars, trains, airplanes, bikes—everything is all run at higher voltages. You have the microprocessor guys that are down at 3.3 volts, and now you have all this electric motivation that’s running in the hundreds of volts.
There is a real disparity between the needs of both of those groups. I don’t think the designers get that; they just design boards, but you just can’t use the same rules for the 3.3 V as you can for the 800 V board.
On the SMT side, they’re stepping up a level. You have the solderability and surface contamination issues. Obviously, you have component issues, but I’m not qualified really to talk about it because we don’t do much with components. My experience is starting with the solder joint and working down. I don’t have much experience above the solder joint, but I know component attachment using lead-free technologies is stressful on the substrate materials as well as the repair and rework they undergo.
Component shortages are causing people to do things with components that they wouldn’t normally do. Normally, they would throw questionable components away. Now, they are trying to fix them rather than take a component off, throw it away, and put on a new one. There might not be a new one, so they’re salvaging. They’re taking components off of boards that are scrap and putting them on good boards. A lot of weird things are happening now due to supply chain issues that weren’t happening before.
To read this entire interview, which appeared in the November 2021 issue of SMT007 Magazine, click here.