Screaming Circuits: QFN and DFN


QFN Solder Mask Issues

Here's another QFN oopsie. Presumably, in this case, the flag pad on the QFN is needed as a heat sink and those vias are designed to conduct heat to the other side of the board. That's all good. But, with... Read more

Lets Get Small

I’ve been slowly working on this microcontroller board (very slowly) for a while. I’m using PCB123 and some new, very small components to put it together. I’m amazed at the changes that have happened recently in this industry. Change has... Read more

Speaking of Common QFN Issues...

Here is the classic QFN via in pad. It simply isn't possible to solder the center pad properly with that much open via real estate. The best way to deal with this is to fill the holes with something that... Read more

Novel QFN Land Pattern

Because the center land is so much bigger then the side pads, QFN solder paste can be a problem if not handled properly. I've written about options before, but here's another approach. I ran across this QFN land pattern the... Read more

PCB123 QFN 28 footprint

First things first. I still haven't received the little ZigBee modules. Microchip said they'd ship out on the 14th so I shouldn't expect any different. I'm going ahead and getting started on the schematic anyway. When I get the modules,... Read more

QFN / QFP switcheroo

Here's an all too familiar face. We see this a lot with chips that have both a QFP (quad flat pack)and a QFN (quad flat pack, no leads) package. Especially if the QFP packaged part has been around for a... Read more

Good QFN, Good QFN Paste Layer

I write a lot here about things that go wrong with various layouts. Hopefully by doing that, I can help some of you avoid common pitfalls. But I should probably write about more good things though to balance it out.... Read more

Parts Library Strikes Again

Here's a little bit of a parts library or wrong package problem. I'm not exactly sure how it happened. The board may have been laid out for a small QFP footprint but then a QFN part was purchased. The footprint... Read more

A Couple of Interestingly Tiny Parts

Yeah, I'm kind of a broken record on this subject. But, you have to expect that given where I work and that I believe in what I do, I'm going to be such a broken record. I ran across these... Read more

A Little Pad In That Via

Here's an interesting via-in-pad situation we ran across a while ago. I'm not sure what the chip is. Probably a processor or an FPGA that generates a bit of heat. The intention with the layout was on the right track.... Read more