A PCB can pass electrical checks and still fail at assembly because the physical component does not match its footprint. Before ordering a board, verify the real part, its symbol pins, its pad numbers and its dimensions as one chain of evidence. This free checklist is for low-voltage hobby projects and applies whether you use KiCad or another PCB editor.

Start with the exact manufacturer part number

Write down the full orderable part number and obtain the current manufacturer data sheet and mechanical drawing. A familiar package name alone is not enough: similar-looking connectors can differ in pitch, orientation, mounting tabs and pin numbering. Save the drawing with the project so another person can repeat the check.

1. Map every functional pin to a pad

Make a small table with the schematic symbol pin number, its function, the data-sheet pin number and the footprint pad number. Compare them one by one. The PCB software connects nets by numbers, so a symbol that calls pin 1 “output” does not make a pad numbered 1 correct for the chosen physical part. Look for intentionally unused pads and exposed pads too.

Worked example: imagine a three-position connector with functions GND, SIGNAL and 5 V in schematic pins 1, 2 and 3. The manufacturer’s drawing shows physical contacts numbered 1, 2 and 3 when viewed from the mating face. Your footprint is drawn from the board top, so the left-to-right appearance may be reversed. Do not infer the mapping from a thumbnail: mark the drawing’s viewing direction, identify pin 1 on the actual footprint, then compare the numbers and intended functions. If the drawing does not settle orientation, pause the design review rather than guessing.

2. Check dimensions and mounting features

Compare the pad spacing, row spacing, hole size, pad size, body outline and mounting features with the manufacturer drawing. Note whether quoted dimensions are nominal, minimum or maximum. For a through-hole part, also compare the lead dimensions with the drill and finished-hole assumptions from the board supplier. For an SMD part, check the recommended land pattern if supplied and account for its specified tolerances.

3. Check physical orientation and access

Inspect where the component will face once assembled. A connector may have correct pad numbers yet point off the wrong board edge or obstruct a nearby part. Check board edge clearance, enclosure fit, fixing holes and the room needed to plug in a cable. A 3D view can help spot obvious interference, but a missing or inaccurate 3D model cannot validate a footprint by itself.

4. Check the board and the generated files

Run the schematic electrical rules check and the PCB design rules check, then inspect each remaining warning rather than automatically dismissing it. These automated checks find many connection and clearance problems, but they cannot know whether the actual purchased connector matches your selected footprint. Inspect the fabrication outputs in a separate viewer and confirm that the board outline, copper, solder mask, silkscreen and drill files are present and correspond to the intended revision.

5. Record the decision

For each unfamiliar or critical part, record the part number, data-sheet revision or date, footprint name, dimensions checked, orientation evidence, and who or what verified the mapping. Mark any unresolved uncertainty before ordering. This turns a vague “looks fine” into a review another person can repeat.

A compact pre-order checklist

• Exact part number and current mechanical drawing identified.
• Symbol pin numbers matched to manufacturer pin functions.
• Footprint pad numbers matched to physical contacts and viewing direction.
• Pitch, pad or hole geometry and mounting features checked.
• Orientation, mating access, board edge and enclosure fit checked.
• Electrical and design rules checked; each exception explained.
• Fabrication layers and drill outputs visually inspected.
• Revision and unresolved questions recorded.

KiCad’s Getting Started guide explains assigning and previewing footprints. Its PCB Editor documentation covers design rule checking and fabrication output. Use your installed software’s matching documentation if menus have changed.

When a reusable review system helps

The checks above are free to use. If you want a fuller record for a whole design, the optional PCB Review Lab toolkit adds a 64-point checklist, 12 worked cases, a workbook and an offline tracker as a £9.95 digital download. It is a training and review aid, not a certified footprint library or a tested board.

For the wider process, read How to Design Your First PCB and Mastering PCB Prototyping.