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Alioth's Journal: [retrocomputing] Surface mount devices

Journal by Alioth

SMD doesn't seem like a term that goes together with 'retrocomputing'. But I finished the hardware for my Spectrum add-on board today, which included three surface mount (SOT-23 packaged) transistors.

It wasn't as hard as I expected (and I didn't need a magnifying glass after all). What I did was to get a small blob of superglue, by picking it up with a off-cut wire from one of the LEDs soldered onto the board, and dabbing a tiny drop of the glue on the PCB where the transistor body would sit. Then using a small pair of snipe nose pliers (needle nose if you're in the USA), positioned the tiny device on the board and let the glue do its job. Once it was stuck, then I soldered the three tiny leads to their pads, using a fine (1mm) soldering iron tip and 0.5mm solder.

I was a bit paranoid about frying the transistors, they are very small and I don't suppose they can sink the heat very well, and a soldering iron tip is significantly warmer than a reflow oven - so I didn't waste time when I flowed on the solder. But they all work fine.

A picture of the board connected to a Spectrum. I've still to fully test the ROM, which I'll do later today:
http://www.alioth.net/tmp/Speccy3.jpg

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[retrocomputing] Surface mount devices

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