Soldering

Soldering

The tools of the trade - iron, solder, flux, and intention

Electronics assembly and repair skills. The ability to permanently join metal with heat is civilization-level technology that fits in your pocket.

The Fundamentals

Soldering iron with scale - precision at your fingertips

Soldering is controlled application of heat to flow metal between components. Simple in theory. A lifetime to master.

The physics:

• Solder flows toward heat
• Flux removes oxides, enables wetting
• Joint strength comes from intermetallic bonds, not just adhesion
• Temperature too low = cold joint
• Temperature too high = lifted pads, damaged components

Equipment Setup

Item	Purpose	Investment Level
Temperature-controlled iron	Consistent heat	Essential
Chisel tip (various sizes)	Heat transfer surface	Essential
Brass wool cleaner	Tip maintenance	Essential
Flux (no-clean)	Oxide removal	Essential
Solder (63/37)	Eutectic = sharp melt point	Recommended
Helping hands/PCB holder	Stability	Highly useful
Fume extractor	Lung preservation	Invest now

Through-Hole Technique

The beginner-friendly method:

1. Insert component, bend leads slightly to hold
2. Heat both pad AND lead simultaneously
3. Apply solder to the joint, NOT the iron
4. Wait for solder to flow and wick
5. Remove solder, then iron
6. Clip excess lead

Signs of a good joint:

• Shiny, smooth surface (with leaded solder)
• Concave fillet shape
• Visible wetting to both pad and lead
• No cold joint "dull crystalline" appearance

Surface Mount Basics

Where through-hole is forgiving, SMD requires precision:

Hand soldering SMD:

1. Tin one pad
2. Hold component with tweezers
3. Reflow tinned pad while positioning component
4. Solder opposite side
5. Reflow first joint to fix alignment

Reflow method:

1. Apply solder paste
2. Place components
3. Heat entire board (hot air, hot plate, or oven)
4. Everything solders simultaneously

Troubleshooting

Cold joint: Dull, grainy appearance. Reflow with fresh flux.

Bridge: Solder connecting adjacent pads. Drag with clean tip or use solder wick.

Insufficient wetting: Solder beading instead of flowing. Clean surfaces, add flux.

Lifted pad: Too much heat, too long. Sometimes recoverable with bodge wire.

Tombstoning: Component standing on end. Reflow with even heat application.

The Meditation

Good soldering is a flow state. Temperature, timing, flux activation - everything working together. The moment when solder wicks perfectly into a joint is genuinely satisfying.

It's also practical magic. You're using heat to flow metal and create permanent electrical connections. This skill predates microprocessors by decades. It'll outlast whatever framework is trendy this week.

See Also

• Electronics Lab - the workspace
• 3D Printing - another fabrication skill
• FPV Drones - where these skills get tested