How many IP3 fiducials should I read?

2017/2/28 6:46:43

Okay here is the deal. I am fairly new to the company here, but one thing I have noticed is that we read way to many fiducials, in my opinon anyway. One for example is this. One assembly was reading 17 fids. Smallest pitch was .25mil I say you only need two globals. I changed it to that, they still placed fine, yet everyone else in my department dissagress with me. I heard someone say something about reading locals for ALL fine pitch (.25 and smaller) within 2.5' radius around the part. I have never heard of that before. If I am right, (which I think I am) When should you use locals? If ever.. Please help give me any feedback you can.. thanks..