How to clean a circuit board

Last Updated on April 4, 2022 by Dave Farquhar

If you want to start an argument, asking how to clean a circuit board is a good way to do it. At the risk of becoming the Internet’s hottest new place to argue, let’s talk about how to go about cleaning one.

Some people get obsessive about how their circuit boards look. While there’s something to the saying that if a board looks good, it works good, the main thing is keeping contaminants off the electrical contacts and preventing dust from causing heat buildup. Unless you have your computer in a translucent case, there’s no need to be overly concerned about how the board looks.

Electrostatic precautions

The first thing you need to do is take electrostatic precautions. A stainless steel kitchen sink is a fantastic place to clean a circuit board because it’s grounded. Any static discharge from you will go straight into the sink and out through the pipes, leaving your board unharmed.

If you don’t have a stainless steel kitchen sink handy, use a grounding strap. Wire up to the third prong of any nearby electrical outlet to pick up ground.

How to clean a circuit board – a dry method

how to clean a circuit board
You can clean the contacts, like the ones on the lower edge of this memory module, with a US dollar bill. It cleans thoroughly without needlessly wearing down the metal. The bill will remove the small marks you can see in the centers of each of the metal contacts.

Sometimes you can clean a circuit board without using any liquids. Sometimes just blasting the surface with a few squirts from can of compressed air and cleaning any dirty contacts with a pencil eraser does the job.

If the board is just dusty, and there are no signs of damage, that’s probably enough. Contacts usually have some caked-in grime, so it takes a bit more to clean them up. There are several ways to do this, but I have a nonconventional trick an old computer technician taught me. Before you reach for any other abrasive, pull out a US dollar bill. Rub the contacts with the dollar bill, which is just abrasive enough to remove dirt and oxidation, but doesn’t needlessly abrade the metal. A few vigorous rubs with a dollar bill often cleans contacts more than enough to put them into working order.

If the dollar bill doesn’t get it done for you, a mild abrasive like a pencil eraser works well. Just rub against the contacts until they’re clean, bright, and shiny again. For really tough spots, you can rub away dirt with a nylon fiberglass scratch brush. This will get the contacts very clean.

Keep in mind you only need to clean exposed contacts that will plug into another board. The printed traces on the interior of the circuit board themselves don’t need any kind of special cleaning. They need to stay covered. That protective covering is what gives the circuit board its color, most commonly green.

How to clean a circuit board with water and alcohol

One reason for the consternation is the idea of combining moisture with something electricity runs through. It’s OK. You’re going to do this with the power turned off and you’re going to let it dry. As long as it dries thoroughly, there is no harm whatsoever in getting the circuit board wet.

That said, you don’t want to use just any cleaner on your circuit board. Many household cleaners are corrosive to metals. One of the main reasons for cleaning a circuit board is to avoid corrosion on the printed circuits.

I have heard of people doing a quick clean by running a circuit board through a dishwasher. This won’t harm the board in any way, although I would normally be more inclined to simply spray it off in the sink rather than using the dishwasher.

For a more thorough clean, put some 91% or 99% pure isopropyl alcohol in a spray bottle, then spray the board down with the alcohol. You don’t need to drench it, just spray down enough to loosen anything that might be stuck to the board. You can then scrub with cotton swabs or even a paint brush to wipe away any debris. The alcohol should be able to get the board rather clean. Alcohol is a good solvent, and it evaporates rapidly. I have heard people argue that it takes hours for alcohol to evaporate, but that just isn’t the case. When it looks dry, it’s dry.

Beware the electrolytes

If a capacitor on the board leaks or explodes, it can deposit its electrolyte on the board. The old electrolyte will eventually eat into the board and damage the electrical traces, so you want to clean off the old electrolyte thoroughly, just as soon as you notice the problem. Alcohol works fine for that.

Cleaning old battery leaks

If the computer’s onboard battery leaks, you need to clean that off just as quickly as you can, because that acid will cause a lot of expensive damage. Wear gloves while handling it, and remove and dispose of the battery first. Older Ni-Cad battery acid spills should be cleaned with a paste of baking soda and water, then rinsed thoroughly. If a Lithium coin-type battery has leaked, dispose of the battery, then thoroughly rinse the board with water.

If you’re not sure of the battery type, try vinegar first, then follow up with a mixture of baking soda and water followed by alcohol. Here are some more tips on battery cleanup.

Keep in mind if you’re dealing with battery damage, you may need some professional help. If all the damage is visible, you may be able to run jumper wires to fix it, but it’s not uncommon for the leakage to get under a chip, which can result in a pretty nasty repair.

Drying extra thoroughly

If you want to be certain it’s dry, you can heat it in an oven for about 30 minutes at about 150 degrees Fahrenheit or 65 degrees Celsius. That’s more than enough time to ensure the board will be thoroughly dry. Alternatively, you can just set the board out in the sun for about 30 minutes too. About 30 minutes in direct sunlight on a warm day is more than enough to dry a board.

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2 thoughts on “How to clean a circuit board

  • April 9, 2018 at 5:47 pm

    I use my old airbrush and airbrush compressor. Also, the various kinds of alcohols on the market contain water as a carrying vehicle. Isopropyl has 2% water in it. You want to make sure you blow dry after using it because it can corrode micro component connections. I don’t even bother cleaning my computer equipment during the winter months when the house heat is on, because of the inherent static electricity in the air. It’s even worse for people with gas heat; because the air is much drier. I clean one final time until spring in the late fall.

    • April 9, 2018 at 6:24 pm

      Fair enough. The problem with cleaning circuit boards is that depending on the problem, sometimes dry cleaning it won’t help. If you’re cleaning up after a leaky capacitor for instance, you’re going to have to take your chances with alcohol, or something similar.

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