The diodes go under the switches, so install them next. As with the other components, they go on the top side of each board half.

Tin one pad for each diode.

Use reverse tweezers to grip diode. Rest both hands on table for stability.

To help hold the diode flat while tacking it down, it helps to first release it to let it lie flat on the board and then re-grip it.

Hold diode in position and remelt solder under leg.

Check that the diodes are oriented correctly and not sticking up in the air. If needed, pressing gently down on the diode while you remelt the one attaching leg will ensure the diode's other legs are flat on the board, similar to with the resistors above. Doing such a fix after multiple legs are attached is much more difficult, and requires partial desoldering. The diode should now be flat on the board and tacked down with one leg.

Solder the remaining two legs. This does not take much solder per leg; a light touch with the solder wire is best.

Test

If you are unsure about the quality of your soldering work, it would be prudent to test each diode with your multimeter. Flip the board over so the diodes are face down.

Your multimeter's diode test function should report a forward bias voltage drop from pad 1 to pad 3 of 0.5v to 0.8v, and a reverse bias reading from pad 3 back to pad 1 of 0L, for open. And similarly between pads 2 and 3.

For more general information about diode testing, how to test using resistance if your multimeter lacks a diode test, or if you have uncommon germanium diodes, see How to Test Diodes with a Digital Multimeter. This tutorial has more general information about them.

Next: Socket MCU