Archive for the ‘Non-Conformances’ Category

Self-Intersecting Polygons, or is it?

Sunday, July 1st, 2012

Have you recently purchased boards from a printed circuit board factory only to find that some complex solderable features on the board that you were going to assemble to didn’t come out correctly? The data you provided to the factory was in the Extended Gerber format (RS-274-X). You notify the manufacturer so that they can determine the root cause of the error. After a few days you are told that your data was loaded into several different CAM programs by the manufacturer and the data resulted in the same shape. Some manufacturers may have even come back to you and stated that different CAM stations running different programs came up with different results, one correct and the other incorrect. Ultimately you are told that your data has illegal self-intersecting polygons that are the culprit.

In my new position at The Bare Board Group (BBG) I have the opportunity to work on a wide range of technology ranging from simple single and double sided boards to advanced rigid-flex designs with HDI blind and buried vias. Its safe to say that we see it all since we are capable of providing boards to meet most design criteria. That being said we also came across the infamous self-intersecting polygon non-conformance on a board we provided. I have decades of experience working with the Gerber format and programming in general. I also like to understand how a problem occurs so that I can prevent it from happening again in the future. I started evaluating the non-conformance and was very surprised by what I discovered at the end of my investigation. To understand the non-conformance and the root cause of the problem you shall first need (more…)