Error-Checking Produce functional PCBs the first time around. DRC Checks Begin here. Run a DRC. Does it report anything? Are there any errors aside from overlapping stabilizer/switch pads? Physical Checks These errors are easy to miss, since some are not scanned by DRC. Is the PCB the correct size? Is USB connector placed at its proper location? Are there any components so large that they will interfere with the chassis? Are the keys placed in correct layout? Are there overlapping parts? Trace Checks Correct routing is important. Do any traces overlap each other? Do any traces go through holes and/or pads? Do any traces fall off the PCB edge? Are there any pointless disconnected traces? Do any traces go so close to pads that they enter their no-mask zone? This can result in shorted circuits after soldering, even if they pass an unsoldered electrical check. Component Checks Will the parts function? Is the pinout of the components correct? Specifically, is the crystal, MCU, and USB connector pinouts correct? Often, on a 4-pad crystal, the crystal pads and gnd pads are placed diagonally from each other. If you have two adjacent same nets or an unconnected pad on crystal, you may have incorrect pinout! Even identical footprint components sometimes have differing pinout. Check the documentation for the parts for their correct pinout. Are you using the correct parts for the task? Are you using the correct footprints? Will the placement of parts cause nearby parts to fail? Heat, EMI, etc. Are decoupling capacitors placed at their correct positions? Near VCC/GND MCU pairs, close to crystal, close to RGB LED, etc. Cross-Checking More eyes is better. Load the gerber in a gerber viewer. Does it render as expected? Let peers error-check your project. Do they find anything suspicious? Does the PCB avoid pitfalls described in this wiki? Aesthetic Checks For beauty-oriented PCBs. Are there any component label silkscreen components that overlap pads or holes? Do any labels overlap other labels? Do silkscreen decorations or branding cover up critical component labels?