SMD Soldering

My brother got me a practice surface mount soldering board with parts down to 0603. I spent an hour or two getting it assembled and learned a lot about surface mount soldering while doing it.

I ended up losing an LED, so L10 isn’t on the board. Which LED is lit progresses rightward before cycling back to L1.

One of the things I learned is to be very careful with winds. Several times I exhaled strongly and blew components around. In the end, my strategy went like this:

  • Decide a number of components to do at once.
  • Apply flux to those pads
  • Set components onto them, pushing them around slowly if nessesary. Remember that the tweezers can get sticky with flux.
  • Clean soldering iron and wet it with a bit of solder. If flux has evaporated from the soldering iron tip reclean and wet again.
  • Hold components in place with downward force from tweezers and go through touching one side of each of them. I’m aware that other people deal with tombstoning in different ways.
  • Solder the other side and clean up. Components can be moved by melting solder on both sides quickly and them pushing them around. Surface tension often corrects component location when both sides are melted.

For the ICs with more pins, the lazy thing worked best.  Generously apply solder  to the legs of the peice making no effort not to bridge them and clean up with some copper wick.

Author: Garth Whelan


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