For the most part, we obviously know most metals rust in water. However, PCB’s are specially designed to be used in many electrical appliances so you may be wondering if the same is likely to happen to your PCB’s, or is there’s something different about them? It’s not quite the same as when your phone gets wet but that could be part of it! So allow us to enlighten you on whether PCB’s rust in water.
Can PCB Rust in Water? Yes, PCB’s can rust in water. When metal ions in PCB’s are exposed to oxygen in water, it bonds, creating an oxide and rusting. The water also tends to activate the salt on PCB components causing it to rust. Rusting worsens when electricity runs through the PCB, causing short circuits and failures.
Although PCB’s have copper, it only gives them the ability to retain its mechanical properties when rusting. It, however, cannot control the electrical conductivity when exposed to water, which is why it causes shortages. So it’s important for anybody to keep PCB’s away from water. Or at least spot water damage on PCB’s before it fails.
How to Spot Water Damage on a PCB
The first and the most common sign of water damage in a PCB is a short circuit. Water has the ability to create paths between different components on a PCB, which might have less electrical resistance. And so, if electricity runs through these paths that cannot handle the high current, they create short circuits.
Most importantly very small components inside the chips cannot resist the high current. This can cause them to burn and stop the functions of the PCB altogether. Likewise, if you experience a short circuit or a sudden fail in PCB’s, it’s very likely due to water damage.
Sometimes these signs will not show up immediately, even if there’s some water damage on the PCB. In such situations observe and check the functionality of the PCB. The most common thing you’ll be able to observe is incorrect functions and signals.
Water can connect the wrong circuits, sending signals to components that weren’t meant to receive them, showing very unpredictable behaviours. But this is a good sign to understand that the water is just spreading within the PCB. So in some cases, you can remove the power source to prevent short circuits or failures and let the water dry completely before using again.
However, before making any assumptions, check if there are any other factors that cause these behaviours. For example, a fragment of metal or a paper clip dropped on the PCB’s can have the same effect and stop it from working. Also, a loose wire can cause PCB’s to behave strangely with intermittent signals from the connected cable. But whatever you’re going to observe, make sure your power source is turned off first.
Now if you’ve already spotted any water damage on your PCB and confused as to what will happen, let me fill you in.
What Happens When a Circuit Board Gets Wet?
PCB’s can get wet in many ways, one way is emersion, where the whole PCB gets wet, and the other by droplets, where it only affects a specific component or a number of components. Although what happens to a PCB when it gets wet is more or less the same, but the approach is different.
The first thing that can happen when a circuit board gets completely wet is that it has a knock-on effect on all its interacted components. After reaching out to these it starts to interrupt the flow of the electricity by creating many unrelated paths. As such when electricity with the same voltage or power passes through tiny components, they burn out. And so the PCB’s will create short circuits or fail.
Whereas, when only a specific component of PCB’s get wet its neighbouring components get contaminated. This will form small silver lines between the traces of these two components linking them. As such when these two components get linked it will cause a shortage in a particular functional block or disable the entire PCB or the device it’s used in.
Now that you know what exactly happens when a PCB gets wet, you might want to know how or if we can fix it...
Can You Fix Water Damaged Circuit Board?
Yes, they can be fixed. But the chances of fixing a water damaged PCB cost effectively depends on the level of damage itself. Some water damage can fail the entire PCB, in which its simply more cost effective to replace the entire unit than to repair it. Whereas, some PCB’s can be fixed if the water damage is minimal or if it has affected a few components and if power was either not engaged at the time, or if power was disengaged immediately.
However, to answer this question I’ll walk you through how to fix a water damaged PCB - where it’s possible.
Equipment you will need:
- 1. Cotton swabs
- 2. Toothbrush
- 3. Compressed air
- 4. Isopropyl alcohol
- 5. Linen cloth
Armed with these tools, follow these steps,
- 1. First, disassemble the device in which the PCB is housed and take the PCB out, being wary of connected wiring.
- 2. Use the linen cloth and thoroughly removeany remaining liquid you see. Never use paper materials as they can scratch the board. Even while using the cloth, never rub it on the board but gently press over the board.
- 3. Then use the toothbrush to brush off any other globs of dried liquid, gently.
- 4. Next, use compressed air to remove any specks of dust or loosepieces in between the components. Spray with quick sprays, as the board could be affected by cold when sprayed for too long.
- 5. Again pat the board gently with a linen cloth to remove all the moisture and let the board dry completely5Next, you’ll need to dampen(not dip or dripping consistency) the cotton swab with isopropyl alcohol.
- 6. Then use these cotton swabs to wipe off stubborn residues without upsetting the components
- 7. Then carefully identifyand replace the parts that are visibly damaged
- 8. Finally, reassemble the device by putting back PCB
- 9. Test the device before fully enclosing the assembly or any casing
Note: Always remember to be gentle with rubbing and handling the components when fixing. If you don’t the parts can be displaced easily from the board and you will need to then replace them with new ones.
So, the next question, just in case you want to do a quick normal cleaning and don’t have any necessary cleaning fluids or compressors to hand.
Can You Clean a Circuit Board With Water?
Although water and any electronics don’t have a good relationship, you actually can use water to clean a PCB. However, if you want to use this option you have to be very careful with the water you use.
Never use tap water as it’s mixed with detergents and cleaning chemicals such as fluoride. Also avoid using solvents such as acetone, naphtha, and ketone. You can use distilled or deionized water for this purpose but they take a long time to dry.
Get hold of a small paintbrush or any other soft brushes you have in hand, dip them in the water and clean the board. Then let it dry completely before using them again. Again as mentioned, be very gentle with the components when rubbing, as PCB’s are very thin and sensitive.
So what if the board itself is corroded, how do you even clean a corroded circuit board? I know it might sound like a pain, but it doesn’t necessarily mean it’s impossible. So if you want to give it a try...
How Do You Clean Corroded Circuit Boards?
To clean a corroded circuit board, you’ll need,
- A small bowl
- Baking soda
- Standard household cleaner (without phosphates)
- Linen cloth
With these things ready in hand, follow these 9 steps carefully,
Remove all the cables from the PCB along with any chips in it. While removing remember the places to put it back after cleaning.
Take a small bowl and add 1 to 2 tablespoons of water with a quarter-cup of baking soda. Mix these two well until it forms a thick paste.
Dip the toothbrush into the baking soda paste. Then apply the paste into the corroded parts of the PCB. Carefully scrub the PCB with the toothbrush to loosen stubborn corrosions. Also, remember to be very gentle to avoid damaging the PCB.
Leave the paste mixture on the PCB for 20 to 30 minutes. During this resting period, the paste mixture will dry - which is quite normal.
Once rested, rinse the PCB with clean water. Rinse well to remove all the traces of the baking soda gently.
Using the standard household cleaner (without phosphates) spray the entire PCB. Allow the spray to rest between 10 to 15 seconds. Then using a toothbrush scrub the surface of the board. Also, remember not to be too harsh with the toothbrush as you already scrubbed well in the previous steps.
Using clean water as described earlier, rinse the PCB again and dry using a linen cloth. Make sure to use a blotting motion while drying - to avoid damaging other components on the PCB.
Preheat the oven to 170 degrees Fahrenheit and turn it off. Then place the PCB inside and leave for two to three hours. This helps remove all the moisture from the board, there may be some sensitive components on boards that means this is not possible to do if so, leave the board out in a dry space to air for 24-48 hours.
Once it’s dried, reassemble the components of the PCB and you’re ready to use.
This might seem like a lot of hard work, of course, the device or equipment must be of critical importance before you decide to go through these steps, and even then, there are no guarantees you’ve solved the issue. It’s often hard to determine if components are already damaged internally. So it may all be in vain.
It may be easier and less time consuming to replace the equipment completely. If you need to do that, or perhaps design a better board more able to withstand damp environments then come and talk to us at RayPCB. We help develop and design components with a wealth of advice on PCB’s for any purpose.