Problems with Multi-CB, bad PCBs, not really helpfull - Page 1
Forum section: electronics / general

author: robint91
author_rank: Contributor
timestamp: March 31, 2020, 05:41:08 pm
content: Rant-mode engageSo the adventure begins again, now with Multi-CB, sigh....So after 15000 € worth of PCB orders with Multi-CB, all of them of very of good quality. Shit happens...It starts even before the PCBs are shipped, two times they delay my order with 2 working days. They changed also the amount they quoted to be less due to the delay but I actually don't care about the cost, but for me the most important factor is the time. I don't care actually if it cost more, but please guarantee your production time.After assembling a few board, I do some basic checks, and one of them is to check for shorts on the supply rails. And of course we find one between +5V and GND. Test second board, also short-circuit on that rail. Mhh, let's test a bare board, lo and behold also a short circuit... So far 100% electrical testing. Check the gerbers, not short visible, also net extraction agrees with me that +5V and GND are not connected. 100% electrical testing is not really 100% so it seems.Mailed to Multi-CB explaining the problem. Got a response that they don't see the short either in the production file, asks if I would have a look at their files. I don't see anything erroneous in their files either. After I mail them my findings, I don't get a reply within 24 hours. I already stated that I need those PCB's yesterday. And I get no comment on my question and remark on how these PCBs could have passed the E-test. If their gerbersets doesn't contain that mistake, I guess then the test program for the probe machine also detects the error that I can measure. Even on the telephone they aren't really helpful in fixing my problem that they have caused. Asking to expedite the process, just gets an empty response that it isn't possible and they want to finish the investigation, which is already 2 days on going.My conclusion is that I can't trust Multi-CB anymore. Why wouldn't this problem happen the next time?I really hope that they would cooperate a bit more, and provide me with boards that I can use as soon as possible. They didn't deliver what they have quoted, even asking for a refund was too much for them. They don't see my problem here.So anyone else had this problem?I have more problems with European PCB fab houses as oversees one.So Multi-CB if you read this, please fix this as fast as possible.To other PCB FABs reading this, trust you can only loose once and never fully regain.

author: jmelson
author_rank: Super Contributor
timestamp: March 31, 2020, 06:47:30 pm
content: Look at the boards under a microscope or strong magnifier. Are there little prick marks in the center of each pad? Those are made by the flying probe tester. If a quick scan of the board does NOT show these marks visible on most pads, then it is a sure bet they did NOT do the electrical test.Are these multi-layer boards? If so, a strong back-light on the board may allow you to see the inner layers. Using an ohmmeter, you may be able to localize the area of the short and then use backlight and magnifier to spot where the defect is. Their photoplot may have a defect or they altered something about the "blowback" from the holes, although this usually ends up causing opens in split planes, not shorts.Yes, if you are paying for full electrical test and they are not doing the testing, then you need to blacklist them.Jon

author: SMTech
author_rank: Frequent Contributor
timestamp: March 31, 2020, 06:49:02 pm
content: There really is no excuse for that kind of fault, I do wonder if some of the testing these days is entirely AOI not electrical.Interestingly we get quite a few of our lower volume PCBs from PCBway who are normally pretty decent. Since they have come back fully online however we've had several orders where the full qty has not passed their QA/Testing and they've had to delay or part ship. It wouldn't surprise me if other PCB shops are having similar issues. The higher volume stuff has slightly longer lead times and no live tracking so you don't always get to know if they hit these snags unless its really bad and they have to fess up.

author: robint91
author_rank: Contributor
timestamp: March 31, 2020, 07:53:11 pm
content: Just looked under the microscope, I don't see any evidence of probes making contact. An other pcb from JLCPCB I do see the scratches.Are we in the current state that chinese PCB fabs are just better?

author: SMTech
author_rank: Frequent Contributor
timestamp: April 01, 2020, 08:53:08 am
content: Bad Chinese fabs are bad, just like european ones. However yes on the whole I'd say there seems to be a higher yield at better quality coming from Chinese suppliers these days. Smaller PCB manufacturers simply don't have the cash to re-invest to keep up. I think the story is a bit different when you're looking at the more specialist high end boards but the super competitive basic 2/4 layer stuff on average might be better from China.However this period is not a good time to judge any supplier, staff are spread more thinly and resources are under pressure regardless of where they are located.

author: jmelson
author_rank: Super Contributor
timestamp: April 01, 2020, 04:28:45 pm
content: Quote from: robint91 on March 31, 2020, 07:53:11 pmI went through just about all the affordable US-based PCB shops in the 1980-1990 period. They all got blacklisted one after the other when I got mutilayer boards with inner-layer shorts, even though I paid for full electrical test. Then, I tried E-Teknet in Arizona. They make the boards in China. At first, they used a bunch of shops there, but had their own guy in house riding herd on QC to prevent this kind of corner-cutting.Now, they own the shops. Their attention to detail is excellent, I've done hundreds of different board designs with them, and had vanishingly small number of issues. I had debris in a through-hole on one board, I can see how that would pass all tests. Twenty years ago they did one with the layers mixed up, but it was a mixed analog-digital board and the isolation mattered. That's all the issues I can remember.So, at least that one outfit is QUITE good.Jon