The moment you click order on a PCB, every mistake in your design gets locked into copper.
Almost every new board design comes back with at least one problem, and each one can cost you a new board order, another round of parts, and weeks of waiting.
One of these checks needs nothing more than a printer and a ruler, and it catches mistakes that even expensive design software will miss.
These are the 9 things I check before ordering any PCB.
Read or watch here in full
#9: Run ERC on your schematic
A PCB layout can only be as good as the schematic behind it, and a perfect layout of a wrong schematic still gives you a board that doesn't work.
The electrical rules check, or ERC, is built into your design software, and it takes only a few seconds to run.
ERC flags things like unconnected pins, two outputs tied together, and a mistyped net label where two points look connected on your schematic but aren't.
Work through every error and every warning on that list until each one is fixed, or you know exactly why it's safe to ignore.
A clean ERC doesn't prove your circuit works though, and it usually won't notice a missing pull-up resistor, missing capacitors next to a chip's power pins, or transmit and receive lines that got swapped.
So go through your schematic one chip at a time with the datasheet open, and check every pin against it.
A second set of eyes helps a lot too, on both your schematic and your layout, because it's easy to read right past your own mistakes.
At Texas Instruments, every chip I designed had to pass a review by a room full of engineers, and it taught me that designing alone invites problems no matter how experienced you are.
#8: Your manufacturer's rules and stackup
Your software's design rules check, or DRC, is only as good as the numbers you give it.
Your manufacturer has its own limits for trace width, trace spacing, drill size, the distance from copper to the board edge, and so on.
Those limits often don't match the software defaults, and that means a board can pass DRC and still come back with shorts or broken connections.
Find the capabilities page on your manufacturer's website, enter their numbers into your design rules, and run DRC again.
Wherever you have the room, stay a little above the absolute minimums.
Boards built right at the limit tend to have more defects once you're manufacturing at high volume.
The layer stackup comes from your PCB manufacturer, and it defines how many copper layers the board has, how thick the insulation is between them, and what that insulation is made of.
Stackup matters most when you have fast signals like USB, Ethernet, or RF circuits such as the feed line to an antenna.
Those traces need a controlled impedance, and impedance isn't the same thing as resistance.
For a PCB trace, that impedance is set by the width of the trace, the distance from the trace down to the ground layer below it, and a property of the insulation called its dielectric constant.
The same antenna trace might need to be around 3 mm wide on a standard 2-layer board, and only about a tenth of that on a 4-layer board.
If you design for one stackup and your manufacturer builds another, you end up with poor wireless range or data errors.
And in designs where that impedance is critical, request impedance control when you place the order.
#7: Every part is in stock and still active
A part you can't buy means a redesign, because once your PCB is made, its footprints are locked in.
Go down your bill of materials and check that each part is in stock with at least two distributors, like Digi-Key and Mouser.
Then look at the lifecycle status of each part, so you don't design in a chip that its maker is already phasing out.
The label to watch for is NRND, which stands for not recommended for new designs.
Always search by the exact full part number, because the letters at the end usually set the package, and the wrong ending can get you a part that won't fit your footprint.
Once everything checks out, order the parts right away, because you'll need them in your hands for the last check on this list.
#6: Your power and ground layout
Power traces are where a clean DRC can fool you, because the manufacturer's minimum trace width tells you what they can build, not how much current a trace can carry.
A minimum-width trace is fine for a signal, but push an amp or two through it and it'll heat up and lose voltage.
So follow each supply from where power comes into the board to where it gets used, and look for thin traces, narrow necks in the copper, and single vias carrying all the current.
A single via can only carry so much current, so use several side by side on your high-current paths.
A free trace width calculator will tell you how wide each trace needs to be for the current it carries.
For high currents, or a supply that has to reach several places around the board, a copper pour or a power plane works better than any trace.
Then look underneath your fast signals like clocks and USB, which need solid, unbroken ground beneath them the whole way.
A fast signal that crosses a gap in the ground copper turns into a source of noise, and that's a common reason products fail certification testing.
This is why a 4-layer board is generally the better choice for designs with lots of high-speed traces or RF, since it gives you a dedicated ground layer with nothing cutting through it.
That's almost impossible to do on a 2-layer board, unless you do all of your routing on the top layer.
#5: The assembled board actually fits
A board layout can look perfect in the flat 2D view and still have parts that physically collide.
Most PCB design software has a 3D viewer now, so load 3D models for your connectors, your tall parts, and anything sitting in a tight spot.
Look for parts that overlap, connectors that hang off the edge of the board when they shouldn't, and parts that turned out taller than you pictured.
Check your cable access too, and remember that the plug on the end of a cable needs more room than the connector it plugs into.
If you already have a 3D model of your enclosure, drop the board inside it.
That shows you whether anything hits the walls or the lid, whether the mounting holes line up, and whether each connector lines up with its opening.
#4: A way to power, program, and probe the board
When your first boards come back, you want to be able to track down any problem one section at a time.
If every power rail is wired straight to everything else, a single short takes down the whole board and hides where the problem is.
So add a zero-ohm resistor in the supply line feeding each major section of your board, which lets you power it up one section at a time.
You can also pull one of those resistors off and put a meter across its two pads to read exactly what that section draws.
Add test points too, so you can get a meter or an oscilloscope probe onto your power rails and important signals.
Many microcontrollers need a certain pin held high or low to enter programming mode, so make sure you can get to that pin too.
None of this adds more than a few cents to the board, and it can save you days of debugging.
#3: The exported manufacturing files in a separate viewer
Your manufacturing files deserve their own check, because you're not really ordering your design, you're ordering the Gerber and drill files you exported from it.
Before you export them, update the layout from your latest schematic, refill your copper pours, and run DRC one last time.
Then open the exported files in a separate Gerber viewer, not the design software that made them, and look at every single layer.
Many manufacturers also show you a preview of the board when you upload your files.
You're looking for a missing layer, drill holes that are offset from their pads, a missing board outline, or solder mask covering pads that need to be soldered.
Parts rotated the wrong way are a very common assembly problem, so if your manufacturer is assembling the board too, check the parts placement file as well.
#2: Every footprint against the datasheet
Library footprints are wrong more often than you'd expect, especially the ones you download.
So open the datasheet for each part and compare your footprint to the manufacturer's recommended land pattern.
Then check the pin numbers, because a footprint can have perfect dimensions and still be wired wrong.
The classic traps are three-pin parts like regulators and transistors, where the pinout can differ between manufacturers even when the package is identical.
Diodes are another trap, because the schematic symbol might label its pins A and K while the footprint labels its pads 1 and 2, and the diode ends up disconnected or backwards.
With connectors, find out whether the datasheet drawing shows the top, the bottom, or the mating side, because reading it wrong mirrors every single pin.
Chips can catch you the same way, especially packages with their pads underneath like a BGA or QFN, where the datasheet often draws the part from the bottom while your footprint is a top view.
Resistors and capacitors are simpler, and you only need to check each package size once, plus the polarity on any capacitor that has a plus and a minus side.
#1: A 1:1 printout with the real parts on it
A paper printout of your PCB is the single best check you can do, which is why I saved it for last, and almost nobody does it.
Print your layout at exactly 1:1 scale so the paper copy is the same size as the real board.
Printers like to shrink pages to fit, so measure the printout with a ruler and confirm it matches the dimensions in your design.
Then take the real parts you ordered and set every one of them on its footprint, right there on the paper, and make sure every pin lands on its pad.
A pad spacing that's off by only 0.1 mm adds up to almost 2 mm across a row of 20 pins, and the pins at the far end won't be anywhere close to their pads.
A part that's too wide for its pads, or a connector whose mounting pegs miss their holes, is obvious on paper in a way it never is in your design software.
The only downside is that it takes a little planning, since you need all of the parts in your hands before you order the boards.
Other than that, all it takes is one sheet of paper, and it catches the kind of mistake that would otherwise cost you a whole new board order.
If you'd like experienced engineers to look over your schematic and PCB layout before you place that order, you can get that from me and other experts inside my
Hardware Academy.