I am currently measuring edge to edge distance between a round BGA pad and a via. The Viewmate tool indicates "inner" measurement is 5.1mil the "outer" measurement is 4.6mil.
Doing the calculation by hand given the center of each circle and the radius, I get the 5.1mil number. Why is this an "inner" measurement and what is the "outer" measurement ?
This is a problem because my pcb design tool sees 5+ mils and decides I have no clearance problems. One of the board houses I use (who probably uses Viewmate internally) uses the 4.6mil value and claims a spacing violation. I need a way to measure apple to apples between tools.