Fine-pitch soldering

Mon, 04/22/2013 - 9:18am
M. Simon, Technical Contributor

I hand-solder. I hand-solder surface-mount devices. So far, my standard practice is to use parts no smaller than 0603s (inch), and for ICs I get them with pitches no smaller than 0.65 mm. This causes problems when I need a component that is too small for me to solder on a board with techniques I have been comfortable with up to now. This is the method I have been using. First, I use a Kester #186 RMA Flux Pen to lay down some flux on the board. Then, I position the component with tweezers, get some solder on the tip of the iron, and then transfer that solder to the pin I'm soldering.

That method is obviously not going to work with the DSA222MAB crystal oscillator that KDS was kind enough to supply me for a project.

So what did I do? I bought something called MP200 Solder Flux, which is really a 63/37 tin/lead solder paste. The tube comes with no point or plunger for the syringe. No plunger is no problem. It is why God made screwdrivers. But no applicator point? That is going to be difficult. Well, God to the rescue again. I pushed a little out of the tube and smeared it around the oscillator, which already had one corner tacked with another screwdriver. Then, I just applied the iron to the paste and pads, and everything went where it was supposed to. No solder bridges.

And of course, I had to apply power to test it. The wave looked pretty good given that my scope-probe ground lead was a little long. And my frequency counter, which hasn't been calibrated since it left the factory, showed what I expected: 40.000000 MHz. Not bad.

M. Simon's e-mail can be found on the sidebar at Space-Time Productions.

Engineering is the art of making what you want from what you can get at a profit.


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