Before You Order Your First PCB: A Checklist of Common Mistakes

Ordering a PCB is cheap. Discovering a mistake after the boards arrive is not: you lose the boards, the parts you soldered and two or three weeks waiting for the next revision. Almost every first-board failure comes from the same short list of mistakes, and all of them can be caught on screen.

Run through this checklist before you click order.

1. Footprints match the actual parts

The most common reason a board cannot be assembled at all.

• Check every footprint against the datasheet of the exact part number you are buying, not a similar part. A SOT-23 with three pins and one with five look alike in a library.
• Check pin 1 and the pin numbering on every IC, diode, LED and connector.
• Print the layout at 1:1 scale on paper and lay the real components on it. It takes ten minutes and catches most footprint errors.

2. The schematic is right before the layout

• Run the electrical rules check (ERC) and understand every warning, rather than hiding it.
• Check polarity on diodes, electrolytic capacitors, LEDs and the power input.
• Check connector pinouts against the cable or module that plugs into them. Mirrored connectors are a classic mistake.
• Confirm voltage levels between chips. A 5 V signal into a 3.3 V pin can damage it.

3. Decoupling capacitors close to every chip

Every IC needs a small ceramic capacitor (typically 100 nF) right next to each power pin, with short connections to power and ground. Placed far away, they do almost nothing, and the result is a board that resets randomly or behaves differently every time you touch it.

4. Power traces sized for the current

Default trace widths are fine for signals but too thin for power. Size power traces for the current they carry, using a trace width calculator and your fabricator's copper thickness. Motor drivers, relays, LED strips and heaters all need wide traces or copper pours.

5. A solid ground plane

On a two-layer board, give as much of one layer as possible to a continuous ground plane. Avoid cutting it into pieces with traces. Signals return through the ground directly underneath them, and a broken ground plane is the source of a lot of noise problems.

6. Design rules match your manufacturer

• Download your fabricator's capabilities: minimum trace width, spacing, drill size, annular ring and board thickness.
• Set them in your PCB tool and run the design rules check (DRC) until it is clean.

7. You can actually buy the parts

A perfect board is useless if a key chip is out of stock for months. Check availability and lead time for every part, especially ICs, and pick alternatives with the same footprint where you can.

8. Mechanical fit

• Mounting holes in the right places and the right size for your screws.
• Connectors at the board edge where cables can reach them.
• Board outline fits the enclosure, with room for the tallest component.

9. Make it easy to debug

• Test points on power rails and key signals.
• A power LED, so you can see the board is alive.
• A programming header brought out cleanly.
• Clear silkscreen labels: component names, connector pinouts, polarity marks and a version number.

10. Final check of the output files

Open the Gerber files in a viewer before uploading. Check every layer, the drill file and the board outline. What you see in the viewer is what will be made.

The checklist

• Every footprint checked against the exact part's datasheet, pin 1 verified
• ERC clean, polarities and connector pinouts checked
• Decoupling capacitors next to every power pin
• Power traces sized for their current
• Continuous ground plane
• DRC clean with the manufacturer's rules
• All parts in stock
• Mounting holes and connectors fit the enclosure
• Test points, power LED, programming header, labels
• Gerbers checked in a viewer

Want a second pair of eyes? Our engineers offer PCB design and design review, from schematic to production-ready Gerber files.