OK. We have a new board with a BGA on it. When have a nice new Glenbrook xray inspection machine. Our troops are trained. Specifically, what are the steps we should use to qualify our BGA soldering process and how should be best use our new Glenbrook machine to our advantage?
Following on from this, 1 What kind of sampling program should we run on instecting the BGA for this new product ? 2 What intervals should we consider changing that sampling? 3 What are the decision points that we should use is assessing the appropriateness of changing the sampling plan?
I believe that at the present time the industry really does not know how to use x-ray inspection apart from indentifying the obvious defects such as shorts, missing balls and gross solder voids. The real utility of x-ray inspection is to recognize: 1. The operator should be looking for uniformity in size and shape of the ball bond image. 2. Departure from uniformity is associated with different process control problems in; screening, reflow temperature profile and thermal deformation of the BGA package. 3. The non-uniformity pattern (signature) can provide the clues as to which problem is being encountered. We recognize this as a science and continue to study it. We plan to post signature information on our web site as the body of knowledge expands.