Soldering Lesson Sheet in PDF format

Soldering Lesson 2017-11-04

☐ Don’t touch the hot end of the iron to your skin, or vice versa.
☐ Wear safety glasses.
☐ Use an exhaust fan so you don’t breathe the fumes.
☐ Use solder that does not contain lead metal, if it is available. “Lead Free Solder”
☐ Turn off the soldering iron when you are not using it.
☐ Wash your hands when you are done.

Learn the basic techniques:
☐ Solder a splice, use heat shrink tubing
☐ Solder a wire to board
☐ Solder a component to a board

☐ Repeat the basic techniques until you are comfortable with them.

☐ Make a 5V circuit tester. (splicing only). Test and debug it.
☐ Make an Arduino Uno header-board-wire connector.
☐ Make an LED and switch module. Test and debug it.

Key Concepts and Order of Operations:

Flux: Solder (for electronics) is a tube of metal with a center core of flux. Flux melts and burns away in a puff of smoke. The flux is there to break the surface tension to allow the solder to wet to the joint components.

☐ Apply the iron to the joint, and then introduce some solder between the joint and the iron to break the surface tension.

Viscothermal Pumping: Solder flows towards heat.
☐ Once the joint is hot enough to melt solder, apply the solder on the opposite side of the joint from the iron, so that the solder has to flow through the joint to get to the iron.

Thermal Mass: Things take time to heat up.

☐ After you have applied and melted enough solder into the joint, stop adding solder, but keep the iron on the joint for a count of 1, 2, 3, to allow time for the iron to fully heat the joint and new solder, so that the solder flows fully into the joint.


Shopping List:

Shield Stacking Headers for the Arduino Uno: Shield Stacking Header Connectors $2 for a set.

Striped circuit board for making Arduino-to-wire connectors: here $6 from DigiKey

Small solder-type protoboards: here $3 each from Adafruit.  here $3 each from DigiKey.

Lead-free solder: SAC305 alloy (Sn = Tin, Ag = Silver, Cu = Copper)
Lead Free Solder $15 from Adafruit. I recommend against using Tin-Copper only solder, I don’t think it melts well.

Inexpensive and reasonably good soldering iron, and stand.
Soldering Iron, $22 from Adafruit. Soldering Iron Stand $6 from Adafruit
Soldering Iron, $13 from SparkFun.
I haven’t personally tested the iron from SparkFun, but it looks like it will do the job well enough.
[The soldering iron stand from SparkFun is reported to be a fire hazard.  Since it is made for lighter weight irons than the ones they sell, it can easily tip over.]

Soldering Fume Exhauster: The only one I can find for a low price is from Amazon. $34.
Soldering Fume Exhauster: $40, DigiKey


Wire stripper

Wire cutter


JMT SM type connectors. Inexpensive connectors that don’t require special tools.

Heat shrink tubing

magnifying safety glasses


Example circuits from the Soldering Lesson:

5V circuit tester schematic:

Code to blink pin 9: here

LED and Switch Module Schematic: 

LED and Switch Module Example Code: here