I have a multi layer board and have 2.5V plane as one of the layer. Some how during testing something go shorted on 2.5V. I am using the Toneohm 950 to detect the plane short after removing whatever components possible. I am left with 12 BGA ICs which cannot be reworked at lab.
But the surprising part is the instrument is detecting the short near power entry. Is it possible that my 2.5V somehow sparked to reach the ground via inner plating?
Please refer the picture below. This is an inner layer of 2.5V(yellow) and blue color vias are ground thru-hole vias.
The minimum distance between the 2.5V and ground via is 15mils.