Hi, I posted on the electronics subreddit this morning but got no attention, so I want to try my luck here.
TL;DR: Not satisfied with Seeed Studio FPC, suggestions on alternatives?
I've been using Seeed Studio's Fusion PCB service for quite some time now, and have always been satisfied with the quality of boards vs. price. I tried their flexible printed circuit (FPC) service and can't say the same.
The first assembled board had a short to ground from the 3.3V rail. I inspected every solder joint for bridges but couldn't for the love of all holy find the culprit. I figured I'd just assemble another one and see if I'd experience the same issue. Top layer? all good. Now for the bottom layer... wait what? There's soldermask covering half of my micro-usb footprint!
Then I started inspecting the other boards and found soldermask issues on other ones as well:
That's when I started thinking the shorting issues were a cause of poor manufacturing. I measured the 3.3V output on all the other boards and found that a part of the ground plane next to the pad was exposed, and lead to solder bridging over. This could be found on other pads as well.
I managed to find one defect-free board to assemble, and it works fine. But one board out of ten is a really poor yield.
I checked to make sure I followed all specifications stated on their website. Then I emailed them and got the response that " the problem was due to [their] manufacturer process limit.", and they offered me a refund.
I applaud them for taking the time to look into it and admit the fault. But I was really just hoping that this was a one-off faulty batch and they'd send me a new one. Especially since the soldermask issue looks like something just went wrong with the machine for a few seconds.
Now I need to find a new place to get FPC's made. Have you got any suggestions? I'm tempted to try Itead Studio but I suspect they're using the same manufacturer as Seeed Studio.