In this lesson students learn how to solder components onto a universal printed circuit board (PCB). They build on their earlier wire-soldering experience and discover how PCBs create permanent, durable circuits using copper pads and through-holes. Students practice bending component leads, fitting parts into correct positions, tinning the iron, applying heat properly, and trimming leads. The tone stays warm and calm, helping students feel confident and safe while working with a tool that requires focus and care.
Student Learning Goals
By the end of this lesson students will be able to:
• Explain what a PCB is and how it differs from a breadboard
• Identify solder pads, traces, and component rows
• Insert and prepare components properly
• Solder resistors safely onto a PCB
• Trim excess leads correctly
• Evaluate a solder joint for quality
Materials Needed
Universal PCB boards
Soldering irons with stands
Rosin-core solder
10K resistors
Wire cutters
Safety glasses
Soldering sponge or brass cleaner
Small fan or open window for ventilation
Journals and pencils
Teacher Preparation Notes
Prepare at least one completed PCB example to show students. Verify each iron works properly and is tinned before class. Pre-bend a few resistors to demonstrate correct shaping for the through-holes. Review safety slides and emphasize that students must follow all rules before being allowed to solder.
Safety Notes
We treat all soldering irons as hot at all times.
We wear safety glasses.
We tie back hair and remove loose clothing or jewelry.
We never touch the iron tip or melted solder.
We work in a ventilated area using a fan or open window.
We unplug irons after use and place them in stands.
We report all injuries immediately.
Warm Up Activity
Hold up a breadboard and a PCB. Ask:
What do you notice is different between these two boards?
Explain that breadboards are temporary and flexible, while PCBs are permanent and used in real devices.
Lesson Flow
Step One: What Is a PCB?
Use the slides to show that a PCB has copper pads and holes to solder components into. Explain that once parts are soldered, the circuit is solid and long-lasting.
Journal prompt:
Why might an engineer choose a PCB instead of a breadboard?
Step Two: Understanding PCB Layout
Show the labeled example positions like C3, C6, D1, D4, etc. Explain that these coordinate-style labels help us place components accurately.
Walk students through the first placement as a group.
Step Three: Bending Component Leads
Model how to hold a resistor by the body and bend each lead downward gently so it fits cleanly into two PCB holes.
Explain that sharp angles can weaken the leads.
Step Four: Insert the Component
Guide students to place a 10K resistor into position C3–C6.
Show how to slightly bend the leads on the back of the board to hold the resistor in place.
Step Five: Prep the Iron – Clean and Tin
Demonstrate:
• Clean tip on sponge or brass wool
• Add a thin coat of solder so the tip is shiny Explain that a clean, tinned tip heats quickly and evenly.
Step Six: Apply Heat Correctly
Model the sequence:
- Touch the iron to both the pad and the component lead.
- Wait one second.
- Feed solder to the joint (not the iron).
- Remove solder.
- Remove iron.
- Let the joint cool without moving it.
Step Seven: Check the Joint
Show what a good joint looks like: smooth, shiny, and cone-shaped. Show examples of bad joints: lumpy, dull, or cracked.
Journal prompt:
Draw a good solder joint and label what makes it strong.
Step Eight: Trim the Leads
Demonstrate using wire cutters to trim the leads to about 1/8 inch.
Remind students to point clipped leads away from faces.
Step Nine: Add Remaining Resistors
Students solder additional resistors into positions:
R1 – 10K – C3/C6
R2 – 10K – D1/D4
R3 – 10K – E3/E6
R4 – 10K – E1/H1
R5 – 10K – E2/H2
R6 – 10K – G3/G6
Encourage students to move slowly and check each step.
Step Ten: Reflect and Inspect
Have students inspect each other’s boards and give warm, constructive feedback.
Remind them that every maker improves with practice.
Teacher Notes for Each Slide
Slides 1–6 Safety basics: Reinforce slowly.
Slides 7–12 PCB overview: Explain differences from breadboards.
Slides 13–20 Component placement: Model each step.
Slides 21–30 Soldering sequence: Demonstrate multiple times.
Slides 31–end Resistor placement list: Guide patiently.
Independent or Group Activity
Students work in pairs to complete three additional joints on a shared PCB, then record which joints were strongest and why.
Vocabulary and Concepts
PCB Printed Circuit Board used for permanent circuits
Pad The metal ring where a component is soldered
Lead The metal leg of a component
Joint The connection between the pad and the component lead
Wrap Up
Ask:
What part of soldering onto a PCB felt the easiest today?
What part should we practice again before moving on to larger projects?
Exit Ticket
Draw one PCB pad and show where the component lead sits.
Quiz
- Why do we use PCBs instead of breadboards for permanent circuits?
- Why do we tin the iron?
- What makes a good solder joint shiny?
- Why should we trim leads?
- What does the label C3 or E6 tell us?
Teacher Reflection
Did students feel confident matching PCB coordinates?
Were they able to recognize good and bad joints?
Would an additional demonstration slow things down in a helpful way?