Circuit Board Design
From a breadboard prototype to a real printed circuit board.
The question
Your breadboard project works, but wires fall out whenever it’s moved. How do engineers make circuits permanent and reliable?
What you’ll discover: the steps from schematic to printed circuit board, what traces, footprints and clearances are, and the options in between.
In simple terms
BeginnerMaking it permanent
A breadboard is perfect for experimenting but not for keeping: connections loosen and wires get bumped. There are two main steps up:
- Stripboard or perfboard: a board with a grid of holes (and, on stripboard, copper strips). You solder parts and wires in place (Lesson 18). Cheap and quick for one-off projects.
- Printed circuit board (PCB): a fibreglass board with copper connections, called traces, made in a factory from your design. Neat, reliable and repeatable.
- Many projects start on a breadboard, move to stripboard, and only become a PCB once the design is settled.
From schematic to board
- Schematic capture: draw the circuit with standard symbols (Lesson 6) in a PCB design program. The free, open-source KiCad is widely used by students, hobbyists and professionals.
- Footprints: assign each symbol a footprint: the exact pattern of copper pads that the real part’s legs will be soldered to.
- Layout: place the parts on the board outline, then route traces between the pads. The software shows unconnected links so you don’t miss any.
- Design rule check: the software checks that traces aren’t too thin or too close together for the manufacturer’s process.
- Manufacturing files: export Gerber files (one per layer: copper, solder mask, silkscreen and board outline) and a drill file, and send them to a board maker.
Go deeper
IntermediateTraces, clearances and parts
- Trace width: wider traces carry more current with less heating. Signal traces can be thin; power and ground traces should be wider. Online calculators based on the IPC-2221 standard estimate the width for a given current.
- Clearance: the gap between separate copper areas. Low-voltage projects need only a small clearance; high voltages need much more, which is one more reason Electronics School stays low-voltage.
- Through-hole versus surface-mount: through-hole parts have legs that go through holes and are easy to hand-solder. Surface-mount parts sit on pads on the surface; they’re smaller and how almost all commercial electronics are built, but tiny ones are hard to solder by hand.
AdvancedGood layout habits
Use a solid ground plane (a large copper area connected to ground) where you can: it gives every signal a short return path and reduces noise. Put a small decoupling capacitor, typically 100 nF, right next to the power pins of each chip, so quick bursts of current come from the capacitor instead of the long supply traces.
Label connectors and test points in the silkscreen printing, add mounting holes, and leave room for the enclosure (Lesson 39). Before ordering, print the layout at 1:1 scale on paper and press the real parts through it to check the footprints fit.
Quick check
What is a footprint in PCB design?
The pattern of copper pads that a part’s legs are soldered to.
Why should power traces be wider than signal traces?
Wider traces carry more current with less heating.
What does a decoupling capacitor do?
It supplies quick bursts of current right at a chip’s power pins, reducing noise.
Words to know
- PCB
- Printed circuit board: a board with copper connections made from a design.
- Trace
- A copper connection on a PCB.
- Gerber file
- A standard manufacturing file describing one PCB layer.
- Ground plane
- A large copper area connected to ground.
Learn more
- KiCad: free, open-source PCB design software
- Lesson 18: Soldering
- Next: Advanced troubleshooting
Electronics School is part of the Discovery Zone. Every activity here runs on small batteries or a USB cable: never wall outlets. The one plug-in tool is the optional soldering iron, set up by an adult.