Hello,
Hope this is the right place to ask for advice on a problem I'm getting. These last few years I've gotten in the habit of making my own minimal microcontroller dev boards that can be plugged right onto a breadboard, with most of the relevant pins broken out. Power stuff, programming connector, and that's about it. They have worked fine until now. They tend to look like this:
https://oshpark.com/shared_projects/ih8ImCyEI pulled a couple of these out to start a new project, I had already populated them a year ago and they had worked just fine. Trying them now, they appear dead, and the programmer won't even talk to them. I did some debugging and found out both of them had failed in the exact same way, while in storage for less than a year!
In this screenshot:
http://dronecloud.org/stuff/pic32_board_via_fail.jpgThere is no more continuity between any the ground vias (under the chip) and their adjoining pads. On both boards I have, all four via->pads have failed where they worked before. The underside of the via I can probe does have continuity with other ground points elsewhere on the board.
I'm just a hobbyist, I don't have any formal EE training, any PCB design knowledge I have is self-taught from the internet, plus a lot of trial and error. Did I design this wrong? Is the via ring thickness too small? Is the trace too thin? Is it a stress issue, a heat issue? The micros get warm, but not hot. I use isopropyl alcohol to swab PCBs after soldering. Even though the PCB worked for a past project, could the alcohol have damaged the pcb long-terrm? I tried reflowing the pads with no success.
The PCB service I use is oshpark, so should be good? 1oz copper thickness.
Thanks in advance for any help with this. I don't understand how this broke aside from a vague "this is probably a stress failure", and I really need to avoid this in the future.