Whoops

September 11, 2010 11:15:08 PM CDT

I ordered a batch of 74LVC74 dual flip flops a while ago, and didn't pay as much attention as I should have. The package was listed as SOT337, and when I see 'SOT' I automatically think of a package with pins at .050" pitch.

Turns out the other name of 'SOT337' is 'SSOP14'.. a 14-pin package with pins at .025" pitch.


Now, I have plenty of experience with .050" pitch. I've designed, etched, and soldered enough circuits with .050" components that I don't consider them much of a challenge any more. I'm used to them, I know how they feel.

.025" pitch is another story.

In theory, it isn't that much of a problem. The footprint for .025" components is basically what PCB designers call 12/12 pitch (.012" traces with .012" of space between them). I'm comfortable making boards down to 10/10 pitch, and the extra couple thousandths really do make things easier.

So I was reasonably confident I could make a breakout, but the first time you look at a package with 40 pins per inch and think, "I have to solder those buggers," your stomach sinks a little.

Well, mine did anyway.

Still, I hate to waste components, and it's always good to push the edges of your skill set.. if nothing else, you get specific knowledge of what you can't do. So I designed and etched a simple breakout board, took a deep breath, and pulled one of the chips out of its bubble in the tape.

I was pleasantly surprised to learn that aligning and soldering the thing was a lot less of a hassle than I'd feared. In fact, it wasn't much harder than working with .050" pitch components.

I'll need to solder a lot more of the little suckers before I feel complacent about working with them, but that's just a matter of getting practice. As of now, I know that working with them is a straightforward process, and that it doesn't take all sorts of time and effort to get decent results.

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