6 PCB Design Mistakes That Can Destroy Production
Just because you’ve got a working prototype doesn’t mean your design is ready for production.
I saw this when I was a chip designer at Texas Instruments. A new engineer was bragging to me that his latest design worked perfectly after looking at just a few units. But testing more of them revealed a fatal flaw, and he had to scrap the design entirely and start over.
He incorrectly assumed what works on a prototype will also work in production. And that same assumption shows up all the time in PCB design.
So let’s go through six common PCB design mistakes that can completely destroy production.
Mistake #1: No Test Points for Key Signals
This is probably the most common mistake I see, even from otherwise solid designers.
If you don’t include test points, your manufacturer has no easy way to verify that the board works before they ship it out. That means there’s no way to measure power rails, check communication lines, or confirm that the firmware was loaded correctly.
Sure, major problems are likely to be caught in your functional testing, but the earlier you catch defects, the better. Some issues might not show up as immediate functional problems.
So what happens? Either they ship you untested boards and leave testing up to you, which is a nightmare when you’re ordering in quantity. Or they charge extra to create a custom test fixture that works around your design.
Also, when placing test points, if you put them on both sides of the board, the factory now needs a double-sided bed-of-nails fixture to reach them. That kind of fixture is much more complex and expensive to build.
You should include test points for every important signal. That means power, ground, reset, communication buses, and any critical GPIOs. But don’t add test pads to RF or high-frequency signals. The parasitic capacitance of the test point can cause issues in those cases.
Put all the test points on one side of the board. The bottom side is usually best, or the side opposite the components. That’s the standard for fixture-based testing.
Keep them grouped together if possible and clearly labeled. Add a nearby ground pad or two to make probing and measurements easier.
Mistake #2: Missing Part Number and Revision on the PCB
This one gets overlooked all the time. It might seem minor, but it can cause a lot of confusion during production.
Let’s say you send a board to your factory. Then two months later, you make a small change. Maybe you update the microcontroller footprint or tweak a capacitor value, and then send a new file set.
But the silkscreen on the PCB doesn’t include a clear part number or revision label.
Now your factory has no idea which version they’re building. Maybe they build the wrong version by mistake. Maybe you lose track of which version they built. And good luck debugging problems if you’re not even sure which board revision you’re holding.
If you’ve made major design changes, you might be able to spot them visually. But a lot of times, that’s not possible. Either way, you need to include revision numbers so you and your factory don’t get things mixed up.
Always include a part number or project name and the revision on the PCB silkscreen. Something like “PN: 1203, Rev B” or “Predictable Pet Tracker, Rev B” works great. Keep it small and out of the way, but still visible.
And make sure it matches what’s in your manufacturing files. That includes your BOM, your Gerbers, and your pick-and-place files. Everything should line up to avoid confusion.
Mistake #3: No Fiducials for Pick-and-Place Alignment
This is another issue that can quietly ruin manufacturability, especially with more complex boards.
Fiducials are tiny circular copper pads with no mask or silkscreen. They’re used by the pick-and-place machine to align the board correctly before placing components.
Without them, your assembly house either has to manually align the board, which is slow and error-prone, or they modify your files to add fiducials if they even tell you.
When you’re prototyping just a few boards, or using very simple chips with low pin counts, you can often get by without them. But for anything going into volume production, you should definitely include them.
Add at least two global fiducials to your board, ideally on opposite corners. That gives more reliable alignment.
If you’re using high-density packages like QFNs, BGAs, or fine-pitch connectors, consider adding local fiducials near those parts too.
Just make sure there’s at least one millimeter of clearance from other copper or silkscreen. And don’t cover them with soldermask.
Mistake #4: No Panelization or Depaneling Strategy
If you’re only making a couple of boards, this might not matter. But once you start producing at scale, especially if you’re using smaller boards, your manufacturer will want to panelize the design.
That means putting multiple copies on a larger panel so they can be assembled together, then broken apart later.
If you don’t think about this ahead of time, your CM might make their own panel, which could mess with your layout. Or they’ll send the files back asking for changes, which slows everything down.
Even worse, poor depaneling design can cause cracked boards, broken connectors, or fractured solder joints when they’re separated.
If your board is under 100 by 100 millimeters, plan for panelization from the beginning. Add mouse-bite tabs or V-score areas, and make sure to keep important components away from the edges.
Talk to your CM about their preferences. Ask about tooling holes, panel sizes, and spacing. Most are happy to send you a panel template if you ask.
Mistake #5: Using Hard-to-Source or Obsolete Parts
This one might sound obvious, but it’s a big issue, especially with how unpredictable supply chains can be.
You might find a part that looks perfect on paper. But if it’s only available from one distributor, or already marked as not recommended for new designs, that’s a red flag.
Factories don’t want to pause your build while they wait three weeks for one missing capacitor. And some might even substitute a part without telling you, which puts your product at risk.
Before you lock down your BOM, check availability using sites like Octopart or Findchips. Make sure each part is available from multiple suppliers and isn’t nearing end-of-life.
Choosing parts that are easy to find and well supported will make your build go a lot smoother.
Mistake #6: Tight Component Spacing and No Room for Rework
When you’re working on an early prototype, it’s tempting to cram components together to save space. That’s especially true on small boards.
But tight spacing can create a lot of problems during production. So don’t pack things in unless you absolutely have to.
If a part fails or is placed incorrectly, your manufacturer might need to fix it. They could need to probe nearby traces, rework a solder joint, or even replace a component.
If there’s no room, they either spend a lot more time doing that work, or they can’t do it at all.
Give extra room around connectors, tall components, and anything that might need debugging or rework. Also, avoid putting tall and short components too close together. That can cast shadows during inspection and even affect solder reflow.
And don’t assume everything will go smoothly during production. It won’t. So make space for human hands, tweezers, and soldering irons. Someone will need to fix something eventually.
