I have a 4-layer PCB, designed in Eagle CAD 6.5. The stack-up is:
- GND (ground)
- DVDD (digital power)
GND and DVDD are solid planes, with vias connecting them to layers 1 and 4.
I have 4 PCBs. Three PCBs are bare - unpopulated, fresh from the fabricator.
In the bare boards (and the assembled one) there is a short between GND and DVDD. It could be a manufacturing defect, but since all 4 boards are bad, it's more likely it is a design problem.
I've manually examined the gerbers in gerbv to see if there are vias that connect to both GND and DVDD, but did not see any. But there are a lot of vias, so I could have missed one.
I've done an Electrical Rule Check (ERC) and Design Rule Check (DRC) - to look for problems. I get no unapproved errors. I've examined all the approved errors to look for problems - there are no overlaps.
How do I find the source of the short circuit?