Screaming Circuits: CAD Parts Libraries

PROTOTYPE AND SMALL VOLUME
PCB ASSEMBLY MADE EASY

How NOT to mark a diode

A while back, I wrote about ambiguity in the markings on electrolytic capacitors. In doing that, I cobbled together a little image to illustrate how surface mount electrolytics are marked. Take a look at the image below: Note how I... Read more

More Eagle CAD Paws

Continuing on from my last post... As I said, I do everything I can to avoid re-using the package footprint when adding the the parts library in Eagle CAD. The schematic symbol can be a different story though. It still... Read more

Eagle CAD paw prints

Unfortunately, I can't generically hand out Eagle CAD QFN footprints without knowing the specific part, but I can illustrate the areas I initially had difficulty with. All of the traps that used to get me seem blindingly obvious now, but... Read more

Let's Get Small, as in 0.3mm

Not long ago, I wrote about a 0.3mm pitch wafer scale BGA we received and were asked to place. The gist of that article was that those parts are very small and we d0n't yet have a process that we... Read more

Missing Mars Probes

Back in ancient times when multi-legged beasts ruled the earth, there were a lot more standards. Or maybe there were just fewer total things resulting in fewer total variations, which looks like more standards. In any case, if you got... Read more

Via in Big Pads

The answer to the question: "is it ever okay to put open vias in BGA pads?" is simply No. It's no, no, no, no, not ever!!! That makes it easy. No technique to worry about. No tolerances. Nothing. Just don't... Read more

Via in Pad x 8

Here's an interesting via in pad case. On the one hand, the footprint is very symmetrical and clean looking. On the other hand, it has open vias in the pads. At first glance, I thought this was a DIP footprint... Read more

How not to treat your BGA friends

Over the years, most of what we see are good PC boards. But some standout in the other direction as examples of what not to do. Some didn't make it through the board house alive. Some were unknowingly rendered useless... Read more

Ambiguity

It's pretty important to have unambiguous polarity markings and pin one markings printed on your PCB. In theory, for SMT parts, it really shouldn't matter; the centroid would take care of the placement orientation. But, you may have noticed that... Read more

Connectors Kill

Lot's of types of components can cause footprint woes. QFNs have their center pad issues. BGAs have escape via issues. But the most common footprint issues seem to be with connectors. At least with chips and discrete silicon and passive... Read more