Every now and then, we get questions on the centroid file (aka pick-and-place file or SMT locations file). Most CAD applications will create one for you. If you use Eagle, download our ULP and run it to create a centroid from your board.
If you want to poke around and need some hints on what’s what you can download our guide on the centriod file. Here are a couple of illustrations from the guide. First, the point of origin needs to be centered in the part.
It should be centered in a box that contains the outline of the pins as well as the body of the part. The chips (above, left) are easy. The connector (above, right), is a little more ambiguous, but as you can see, it’s centered around the imaginary box containing the area. Top-side rotation goes counter-clockwise as shown (below, left) and rotation on the bottom side is simply a mirror image, left to right with clockwise rotation.
Diodes and other passives should have their zero rotation vertical, with pin one (if there is one) facing up. That would place the cathode up for diodes and the positive side up for electrolytics and other polarized two lead parts.
If you get dizzy spinning counter clockwise, go to Australia