Of more interest here is the regulator component itself. This is the small 5-pin chip midway up the right-hand side of the board. It is a surface-mount SOT23-5 part, approximately 3mm by 1.5mm, far smaller than a grain of rice. Building this breakout board was more an exercise in seeing if it was possible to hand-solder these parts than anything else, since they are widely available for cheap on t'Internet.
So how did I do it? The first step was choosing a hand-soldered footprint for the part in KiCad. Then, once the boards had arrived, this part obviously had to be soldered on first:
- Apply solder to the pad under one of the further-apart pins (on the left in the picture)
- Place the chip over this pad with a tweezers and hold it in place
- Melt the solder on the pad until it flows over the pin
- Solder the other pin on the left-hand side
- Solder the three pins on the right-hand side together.
- With a desoldering pump (braid should work too), remove the excess solder from these three pins, so they are no longer shorted together.
Tweezers and magnifying glass (or low-power microscope) are essential, unless you are some sort of assembly robot. Fine-gauge solder and a fine-tipped soldering are helpful too.
Note that the circuit itself helped me "get away" with the final two steps of the procedure above: of the three pins on that side of the regulator, one is NC and the other two are connected to Vout. However checking with a continuity tester indicated that they were no longer shorted together, so the pump had worked as expected.
So the experiment being successful, the next step is to build more surface-mount parts into my designs. 10k resistors and 100n capacitors crop up very often so they would be obvious targets for replacement. Stay tuned!
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