Screaming Circuits: QFN and DFN

PROTOTYPE AND SMALL VOLUME
PCB ASSEMBLY MADE EASY

QFN Custom Stencil Layer in Eagle

It's been said over and over that you don't want to leave the solder paste opening wide open for a QFN center pad. 50 - 75% paste coverage will get you bets results. With full coverage, your QFN can end... Read more

Via-In-Pad Myth #5.A

I received a couple of good questions on my prior post about vias in QFN or QFP pads: "I have a few questions about the second photo. The thermal vias in the center are masked over, doesn't this make it... Read more

Hand To Machine

It's getting very difficult to hand solder many parts these days. Some people give it a try, but in general, if you're dealing with the really tiny parts or leadless parts, it's just not possible, or at least not practical.... Read more

Narcissistic Parts

Maybe not completely narcissistic, but at least self-centered. Or, self-centering. Okay, are you lost now? Am I making any sense at all? Well, I'm going to say that it doesn't matter, because the world-revolves around me. But what I am... Read more

Land Patterns - Equal and Not Equal

I was recently asked a question about QFN package varieties. The questioner wanted to know if different package variants of 16 contact QFN packages, such as HUQFN, DHVQFN, SQFN and such, all shared the same footprint. If they did, the... Read more

AT Tiny is Tiny

I just spotted a note on Twitter, from SiliconFarmer, referring to the ATtiny44A coming in a 0.45 mm pitch QFN as well as a 0.5mm pitch MLF package. (In practice, an MLF is the same as a QFN, by the... Read more

Funky QFN Land Patterns

I've described the optimal way to create your land and solder paste layer for QFNs a couple of times before. But that was for a standard square QFN or rectangular DFN. What happens if you look at the bottom of... Read more

Re-runs

I've been pretty occupied with the upcoming Embedded Systems Conference in Boston. The exhibition is next week on Tuesday, the 21st and Wednesday the 22nd. Screaming Circuits will be in booth 809. Stop by if you happen to be at... Read more

Easy Reading for a Long Weekend

The holiday is upon us and most folks here in the US will have a three day weekend. Of course, when you're an engineer on deadline, all too often holidays don't really mean that much. Here's a little food for... Read more

All Leadless

It wasn't too terribly long ago that just about any design could still be built all thru-hole. Okay, maybe it was a little longer ago than that. Once the big CPU chips stopped showing up in PGA (pin grid array),... Read more