Step 8: Soldering (part. 2)

In this step, we are going to solder the bluetooth serial module :

- Solder the yellow wire to the GND pin
- solder the red wire to the 3.3v pin
- solder the orange wire to the RX pin
- and finally, the white wire to the TX pin
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This is a a great step-by-step!

If you decide to solder this type of Bluetooth module in this way, be very careful, and use flux! I've broken a couple of modules using this method. The connections on the side of the module are fragile, and if the wires are pulled in any way, the connections on the board are likely to break off. I ruined one module/board just by putting too much heat on the terminals while soldering and they fell off. Since I didn't use flux, the solder was refusing to stick, and it forced me to apply to much heat. On another board I was able to get the wires soldered, but then the power wire broke with some very light touches, and the exposed copper terminal came with it.

It might be better to create a footprint for this module on the board that we etched in earlier steps. Then we could place the module on our etched board and just drop solder on the terminals that are needed. It's obvious why the author didn't choose this approach. Doing so would make this Instructable less-usable, because the Eagle file would have this board's footprint on it, and that would mean users would have to purchase the exact same module (which might be difficult to acquire, or out of production).

In conclusion, if you solder the wires to this type of module as shown in the photo, be very careful both during and after soldering, and use flux to get the solder to bond efficiently!