How to Solder Through Hole Components: Step-by-Step Guide

To solder through hole components, insert the component leads into the PCB holes, heat the joint with a soldering iron, and apply solder until it flows smoothly around the lead and pad. Remove the heat and let the joint cool to form a shiny, solid connection.

Syntax

Here is the basic process to solder through hole components:

• Insert component leads: Place the leads through the PCB holes.
• Heat the joint: Touch the soldering iron tip to the lead and pad simultaneously.
• Apply solder: Feed solder wire to the heated joint until it flows and covers the pad and lead.
• Remove heat: Take away the soldering iron and let the joint cool naturally.

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Insert leads -> Heat joint with iron -> Apply solder wire -> Remove iron -> Cool joint

Example

This example shows soldering a resistor onto a PCB:

• Insert resistor leads through holes.
• Heat the lead and pad with soldering iron for 2 seconds.
• Feed solder wire to the joint until it forms a shiny cone shape.
• Remove solder wire first, then iron.
• Let the joint cool without moving the component.

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1. Insert resistor leads through PCB holes.
2. Heat lead and pad with soldering iron tip.
3. Apply solder wire to heated joint.
4. Remove solder wire, then iron.
5. Let joint cool to solidify.

Output

A shiny, smooth solder joint connecting the resistor lead to the PCB pad.

Common Pitfalls

Common mistakes when soldering through hole components include:

• Cold joints: Caused by moving the joint before cooling or insufficient heat, resulting in dull, cracked solder.
• Too much solder: Can cause bridging between pads and short circuits.
• Insufficient solder: Weak mechanical and electrical connection.
• Overheating: Can damage components or PCB pads.

Always keep the soldering iron clean and use the right temperature (around 350°C/662°F).

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Wrong way:
Heat joint briefly, apply solder, move component immediately.

Right way:
Heat joint properly, apply solder, remove heat, wait for cooling before moving.

Quick Reference

Step	Action	Tip
1	Insert component leads	Ensure leads fully pass through PCB holes
2	Heat joint	Heat both lead and pad simultaneously
3	Apply solder	Feed solder wire until joint is shiny and smooth
4	Remove heat	Remove solder wire first, then iron
5	Cool joint	Do not move component until solder solidifies

Key Takeaways

Insert component leads fully through PCB holes before soldering.

Heat both the lead and pad together for a strong solder joint.

Apply solder until it flows smoothly and forms a shiny cone shape.

Avoid moving the joint until the solder cools to prevent cold joints.

Use the right soldering iron temperature and keep the tip clean.