Cleaning GBA Corrosion

The Gameboy Advance came out quite a while ago, with the last game for it published by Nintendo coming out in 2006. It's probably been a while since you touched your Gameboy Advance, which means it may be in terrible danger if you left the batteries in. As the battery depletes, hydrogen gas builds up in it. This can create pressure that causes the battery to rupture and release its electrolyte, which is an alkaline substance (potassium hydroxide). This substance can corrode the battery terminals, causing them to not work. Worse, it can get into the motherboard and corrode the traces, which is a much more serious issue!

I unfortunately ran into this issue when I felt nostalgic and decided to play Pokemon Crystal. One of the battery contacts had severe buildup of corrosion, and I had to open up the GBA to see if it had reached the motherboard... and it had. There's a lot of information on cleaning up the GBA spread over the internet, so I wanted to put it all in one place for my own future reference and for anyone unlucky enough to have to deal with this.

My own attempt to fix the GBA is still a work in progress, but I wanted to document what I've done for both informative and entertainment purposes.

Ingredients

You will need:

White distilled vinegar. What you get from the store is fine. Vinegar will react with the corrosive material. There is a common misconception on the internet that AA batteries leak 'battery acid', but this is false. Car batteries leak a sulfuric acid, but AA batteries do not, which is why vinegar can react with it!

90%+ Isopropyl Alcohol (Rubbing Alcohol. We need this to clean up the vinegar after it is applied. You don't want vinegar left on your board. 90% is better. 70% is passable, but it will have more water in it, so it will leave streaks, take more time to dry, and increase the probability of a short.

Cotton Swabs. You will need these to precisely target inside the motherboard.

Paintbrushes. Buy some small cheap paintbrushes. You will use these to get to places the cotton swap cannot get to.

Three cups you will not drink from. Use one to store the vinegar and one to store the alcohol. The third one should be used to keep track of screwdrivers. Mark the cups.

Paper towel. Lay your GBA on a paper towel.

Screwdrivers. You will need one small one that is Philips head or flathead, and one that is three-sided.

Latex gloves. Optional, but will protect your hands. You don't want the corrosive material on your skin.

The Journey

Assessing the battery damage

First step is removing the battery casing and look at the batteries. One of your batteries may be so swollen that you have a hard time getting it out with your hands. In my case, the battery was basically fused to the terminal so I couldn't budge it. With your gloved hands, you can try rotating it to loosen it up a little. If you have a safety pin, you can gently prod at the corrosive material to remove it. It will form a powder that you need to remove later. I used pliers to remove the swollen battery, but you can also use a flathead screwdriver, anything that gives you leverage.

Once you've disposed of the batteries, the next step is to look at the terminals. Note which ones are messed up. The left-hand terminals are not connected to the motherboard, so if those are the only ones with corrosion, you may be in luck. The right-hand terminals are connected to the motherboard, and so corrosion there can enter and affect the motherboard. This is a worse situation. I had bad luck and the corrosion had affected the motherboard.

After removing the batteries. You can see powder on the battery case and some kind of white substance further in

Opening the case

Use your screwdriver to remove the 5 three-point-star screws and the 1 philips head screw. Put these in a container to keep track of them. You can put them in a cup, or in a plastic tackle case. I began with putting them in a cup but switched to putting them in a plastic tackle case when I realized this project was going to take longer than I expected.

Gently open the rear part of the case. The side grips may come off. That's normal - just keep track of them somewhere safe. The same goes for the power switch.

Take a look at the motherboard. Is there any corrosion near the terminals? If you have corrosion near the right terminal, then it is likely you will have corrosion near the power switch. Also try to see if there is any corrosion under the motherboard, as this means you may need to disassemble the GBA further to flip it over. Once again, I had the bad luck that some corrosion was on the other side.

There is another screwdriver that holds the motherboard in place. Unscrew it and flip it over gently - you don't want to be rough on the ribbon cable.

Cleaning the corrosion

Check out the big chunk of corrosion on the terminal
You can see the corrosion has spread near the power switch

Dip your cotton swab in vinegar. You don't want it soaking wet, just moist. Tap it against the terminal. You will hear a crackling noise and see some bubbling - this is a sign of the vinegar reacting with the potassium hydroxide. It will not just disappear right away.

Use a different cotton swab and dip it in alcohol. Once again, not soaking wet, just moist. Tap it against the areas affected with vinegar. You will know that you have cleaned it enough if it does not smell like vinegar. Wait a few minutes for it dry, smell it to make sure you got all the vinegar. If it smells neutral, then you're good. If not, follow the scent to see where it comes from and apply more alcohol to the source of the vinegar.

After several rounds of vinegar
More rounds of vinegar have gotten rid of the difficult-to-get-to parts at the base of the prongs

Continue applying vinegar and cleaning with alcohol until the corrosion is gone. If the corrosion is bad, it will take a lot of application. Don't rush it... take your time. Cleaning it is not urgent - any damage that may have been done has already been done.

For areas where you want to be careful or where the toothbrush cannot reach, use your tiny paintbrushes. Remember to mark one paintbrush for vinegar and one for IPA.

The flipside of the terminal. You can see corrosion near the terminals
The corrosion won't always be obvious - that darker blue near the terminals is also corrosion

Use a paper towel to clean up the bits of corrosive powder that will fall off.

What do you do if you get a little over-zealous with your vinegar application? Quickly apply that alcohol! You can also gently dab with a paper towel to soak up the excess moisture.

Your GBA probably has no residual charge in it if you haven't touched it for years, so it is unlikely that you will have a short-circuit. Nevertheless, be careful if you are using 70% isopropyl alcohol, as it has more water.

Flaking

I spent several days cleaning. The big chunk of corrosion on the terminals was my first concern. It was like ice in thickness, not going easily. It took many, many rounds of vinegar and IPA to clean the corrosion. I also needed the paintbrushes to get under or between the terminals. It took a while, but I was able to get that off.

The terminal connected to the motherboard was in pretty bad shape due to the corrosion, and I'll probably need to replace it. The plating is gone.

Terminal looking bad

Once both terminals were cleaned, it was time to move to the motherboard. I cleaned it as I did with the terminals, with a lot of IPA to flush it out since we were now getting near important electronic components. I noticed that there were some dark black lines on the motherboard, but I didn't pay them any mind until I did another application of vinegar and found, to my horror, that the light green paint just disappeared to expose the copper underneath.

Before flaking
After flaking

The light green 'paint' is called 'solder mask.' The purpose of it is to protect the copper, which contains the traces. If the paint is chipping, that's bad news because it means that corrosion has gotten underneath the mask and may be eating at the copper. Very bad news!

This was the point when I realized that this was not going to be a simple cleanup like the cases I'd seen on YouTube. I sought out the assistance and got help from the knowledgeable and patient people at the GBA Modding discord.

The path forward: remove the damaged solder mask, clean the copper, see if traces were damaged, and repair them with soldering if necessary (and possible). Then apply solder mask on top to protect the copper.

Cleaning the copper requires a lot more care. Leaving vinegar on the solder mask isn't great, but it can damage the copper. If there is corrosion on the copper, however, you don't really have a choice. You need to go in with the vinegar and then really flush out with IPA.

I thus proceeded, over the course of a few days, to clean as much as I could. I finally got all the corrosion off. Unfortunately, the corrosion had left its mark and some of the traces did appear to be damaged. The next step would involve soldering, a skill I did not have.

Pausing

Around this point I felt like I'd gotten in over my head. I was aware that leaving the GBA's copper exposed to the air could cause oxidation, but I could not tell how quickly it would oxidize. I wanted to stop the project because other life obligations had increased in priority, but I didn't want to sabotage the project either.

I decided, out of an abundance of caution, to cover the exposed copper with solder mask. In retrospect, this was probably excessive and only added extra work, but I really had no idea when the next time I worked on this would be - months, years? - and I wanted some insurance that the copper wouldn't oxidize. Thus began the next part of the project - learning how to apply solder mask, how to cure it, and how to remove it.

Solder mask isn't really meant for home projects, as far as I can tell, and all the solder mask vendors were direct from China with no instructions on how to apply it. I was relying heavily on Reddit and Discord posts from people who had used it before. I eventually found some that seemed highly recommended and I bought it.

Solder mask is more like gel nails than regular nail polish - it requires UV light to cure and without it, will stay spreadable even in dry air. Step 2 was buying a UV lamp. I read a lot of conflicting information on how much power you needed and for how long you needed to cure. I also could not tell if the UV lamps to buy were even as powerful as actually advertised. I bit the bullet on one from Amazon that was wide enough to place over the motherboard.

Finally, I knew I would need to remove this stuff eventually when I got back to work. I bought fiberglass pencils to remove the solder mask. Be careful with this stuff - you should wear gloves and not touch the fiberglass particles.

I wasn't going to just try it out straight on my precious GBA, though. I was treading in uncharted territory. I was concerned the fiberglass pencils would damage the copper. I also had no clue how the solder mask would cure. I thus set out to find a simple electronic that I could test the materials out on that wouldn't be a big loss if it broke. I settled on a calculator from the dollar store.

I busted open the calculator and used the fiberglass pencil to remove the solder mask. Be careful with this stuff - you should wear gloves and not touch the fiberglass particles. They can get embedded in your fingers and cause damage! I recommend working on a surface with paper towels so it is easy to dispose of the powder. I kept rubbing the pencil until the copper trace was revealed. I tested the calculator - still worked fine. The pencil had already been ground down substantially.

The copper of a dollar store calculator's PCB has been exposed

Next part was the solder mask. I learned that you needed to apply very thin layers or no amount of curing would work. I would apply some on a paper plate as a sort of 'palette' and then use the paintbrush to pick up some up and spread it as evenly as possible on the PCB. Once I got a good coverage and good thinness, I set up the UV lamp. I set it for 15 minutes, which wasn't enough - rubbing the paint with a dry paintbrush picked up a lot of residue. It took 30 minutes. I tested the calculator and yeah, still worked.

With the proof of concept complete, I decided to work on the GBA. My friend had a more powerful UV lamp, so I went to her place to try it out. The UV lamp she had was more like an igloo, which meant less light was wasted. This is good because I really needed many layers and thus many cycles of drying. I also found that I wasn't putting on the layers thin enough because if I rubbed with a cotton swab and not the paintbrush, there was still a lot of residue.

I had covered most of the exposed copper, but the paint was not blocking all light. I decided it was good enough as I couldn't keep working on this thing with the looming life obligations. I used the cotton swab to get as much of the uncured parts off as I could, but from then on the GBA needed to take a break. I put it in a plastic bag, and then put that plastic bag in rice to get any moisture. Once again, overkill, but I think you can tell that I was deep in this project and the last thing I wanted was to fumble it because of moisture. I kept the GBA in a dark place.

-shrug-

Cleaning

In between smelling the board for signs of vinegar and IPA, I also cleaned the buttons and side grips. This GBA had been with me on many trips and probably accumulated some amount of potato chip residue. I figured the least I could do while I had it open for open-heart surgery was to clean out the other bits so it would be nice and clean.

Let me start by saying - you don't want to use vinegar and IPA for this. IPA will actually weaken the plastic and the rubber. Instead, just use warm water with some dishwashing detergent. The buttons are pretty easy to clean. Use a toothpick to get into the corners of the shoulder buttons.

This part was very nice and meditative. I actually enjoyed it a lot, the sense of restoring this console to something better and cleaner.

Once all the parts were clean, I put them in a plastic bag to not lose them.

Current status

The GBA is chilling in a drawer with the solder mask and the rice. I plan to go back and remove more of the new solder mask.

I also need to learn rudimentary soldering skills. I've been assured that it is not difficult to do the work needed to fix my GBA, but I would like to practice before I get a very hot iron near my console. My life situation has changed so that I now potentially have a new spot to solder, which was something that stopped me before.

I bought a GBA in the same color as the old one in the case that it was just too far gone from the corrosion, or that I did something that broke it.

The journey of the GBA ruined by corrosive juice is not over yet, but it's clear that this started as what I thought would be a simple DIY project and instead turned into learning a lot more about electronics than I expected. I'm not excited about a childhood toy potentially being unusable, but I am happy for the opportunity to learn more about how it functioned and to learn about electronics in the process.

Works Cited