Issue link: https://iconnect007.uberflip.com/i/1428512
12 PCB007 MAGAZINE I NOVEMBER 2021 bury certain components in the board using different types of material. e problem is when you have some of it buried in the board and some buried com- ponents behave like electri- cal faults. As a resistive net- work, it could be higher than the continuity thresh- old required. Similarly, if you have capacitance built in, you could get charge time and leakage which will screw up the results of a standard test. You must be able to provide both tests in one session. It gets tricky. Holden: I don't think a lot of designers realize that the very fast opens and shorts testers are not necessarily measuring any kind of resis- tance. ey have a relatively large window to differentiate an open from a short. Kolmodin: e standard electrical testers, be it a fixture tester or a flying probe, have metering systems and you tell them this board generi- cally—for the basic opens and shorts test to make it easy—is I have this many networks and an endpoint-to-endpoint resistive value that should not exceed 10 ohms. It then mea- sures, and if it's over 10 ohms, you fail. It's the same thing with leakage; no networks or adja- cent networks should have any leakage. e isolation between the two should be 10 meg- ohms or higher. If it's less, that's considered a leak. We're adding different metering systems. You might have one machine that has three dif- ferent meters—one for doing standard opens and shorts, one to do inductance, and one to do capacitance. Right now, you can't buy a machine off the shelf that can do all that. We're working on integrating that into a machine so all the meters are there and it does it all. As an equipment supplier, you've got to be there machines for doing inductions and such like that. at's how we're seeing it. Shaughnessy: What do you see going on with test and inspec- tion? e good, the bad, the challenging? Kolmodin: We're seeing more requirements from some of the manufacturers and that has forced us to invent ways to do things differently. Some of our equipment now can pro- vide the TDR, the standard test, the buried inductance testing, buried capacitance testing, and buried resistive test- ing all on one machine so you don't need a lot of other equipment. You have to go this way to stay competitive because you can only cut your margins so far; aer a while you won't com- pete anymore and you still need to pay your employees. We are seeing some onshoring again. We are seeing a lot more of the hotshot stuff under ITAR agreements, and some of the military applications. Overall, I think we're getting stronger again but the function for success is definitely automation. I'm speaking for test in general, not just us. Happy Holden: Todd, are you testing bare boards or assembled boards? Kolmodin: With very small exceptions, it's all bare board level. Holden: So, the test is getting more complex because the printed circuit itself is getting more complex with newer technologies? Kolmodin: Exactly. Your standard 8-, 10-, 12-, 16-, and 20-layer boards—we see them up to 30+ when you get into backplane. ese engi- neers figured out some time ago how they can Todd Kolmodin