I'm working on a project that requires an ATSAMC21 microcontroller. I've got a reasonably good setup; air reflow system, USB microscope, ESD mat... the works.
I soldered the chip on the board using solder paste and I wanted to test to make sure the connections were good. When using my multimeter to do a continuity test, I keep getting a short between two non-adjacent pins. The pins are both SPI pins, and there are no other components on the board. The solder looks really good, so I'm kind of out of ideas. The chip itself could be damaged, but what are the odds that the two pins that happen to be damaged are two non-adjacent ones that I actually need (there are 100 pins on this microcontroller). I am measuring the short on all unpopulated pads that these pins are connected to. The weirdest thing is that the pin between them is not shorted to either of them. I also checked an unpopulated board, and these pins are not short on it. Does anyone have any ideas about what this could be?