PCB Short Issue

Question

I recently designed two boards and had them manufactured for a project I am working on. Before I soldered any components, I checked the continuity of some of my connections and discovered that there is a short somewhere between my 12V line, my 5V line, and GND. It also appears that some of the other connections are shorted as well. I ordered two of each board and there is not much consistency as to which connections are fine and which aren't. For example, on one of the 4 boards the 5V lines are not shorted to the 12V/GND but the 12V and GND are.

They few things I think might be the culprit are:

1.) Some of the traces appear to be faded. There seems to be a correlation between the traces that are faded and the connections which are shorted. However, it doesn't appear that the etching for the traces is actually broken.

2.) I used ground planes on both the top and bottom layer of my boards.

3.) I noticed that the decoupling capacitor is not wired properly, and can just be bypassed.

I would like help narrowing what might be the cause of my issue, as these are the first boards I have designed. I have included images of both of the board layouts below.

Answer 1

Good job testing them before populating the board.

Based on the pictures, it looks like the place that made the board did a crappy job etching them. Some of the copper that was supposed to be etched away remained.

This could also happen if you didnt follow the minimum specs that the company recommends - they all should list minimum trace widths and clearances that you can set in your PCB design software to ensure the board can actually be made properly.

If you did follow their guidelines, it shouldn't take any more than those photos and an email to get a decent place to remake the boards.

If these are prototypes, and you really don't want to wait for new boards to arrive, you can try cutting the shorted areas with a sharp utility knife, if you can find them all. It might work, it might not - and you will have to test every trace against every other trace it runs near.

You can avoid this in the future in a few ways:

• Use a higher quality PCB manufacturer
• Bigger clearances between traces, where possible
• Electrical testing at the board house. It costs a little more, but helps ensure that what you recieve is what you asked for. It may not catch everything though.