(Topic ID: 170674)

Stripping battery corrosion with a strong acid


By barakandl

2 years ago



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  • 37 Pinsiders participating
  • Latest reply 7 days ago by PappyBoyington
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    Topic index (key posts)

    4 key posts have been marked in this topic

    Post #7 Cleaning technique Posted by barakandl (2 years ago)

    Post #8 Cleaning results of the acid compound on WMS system 3-6 MPU board Posted by barakandl (2 years ago)

    Post #10 Results of applying the acid compound on WPC MPU boards Posted by johnwartjr (2 years ago)


    Topic indices are generated from key posts and maintained by Pinside Editors. For more information, or to become an editor yourself read this post!

    There are 88 posts in this topic. You are on page 1 of 2.
    25
    #1 2 years ago

    Thanks to Vid for this idea.

    I decided to try using hydrochloric acid to remove battery damage and it worked very well.

    The product I used was Zep Acidic Toilet Bowl cleaner. Found at Menards for about $4.
    20161008_103723 (resized).jpg20161008_103742 (resized).jpg

    ***Eye protection and Nitrile gloves was worn and this should be done outside or in a well ventilated area***

    To start I knocked off all the fuzzy corrosion I could with a flat head screw driver into a trash can. Didnt dig to deep, but got all the solder mask and chunky corrosion off and the board looked like this. Most of the damage was just on the ground track. Few via and tracks around u11 where damaged. In hindsight, I should have clipped all the components off the corroded area and removed the solder mask better.

    20161008_103645 (resized).jpg
    20161008_103656 (resized).jpg

    Now I applied the acid. I decided to basically follow the direction on the bottle. I just squirted it right onto the corroded areas. A chemical reaction begins to happen immediately. I am not sure what kind of gasses where created, but they where nasty smelling. Do this outside or with some kind of vent fan. I could hear foam bubbles popping.

    20161008_104041 (resized).jpg

    I waited the five minutes and came back. No more fizzing. I could see a very noticable change in the board already.

    20161008_110257 (resized).jpg

    I did the back side of the board next. Another five minutes.

    20161008_111254 (resized).jpg

    Next up the instructions on the bottle said to scrub. I used an old beat up wire brush I didnt care about. Added a bit of water and made a soap like suds. I could see the suds rapidly turned black with little effort scrubbing.
    20161008_111848 (resized).jpg

    Washed the board with soap and water. Then used naptha to cut the water so it would dry fast. I was left with a very nice starting point

    20161008_124302 (resized).jpg

    The board took solder well and gave me no trouble when reworking it. I still replaced all the parts in the corroded area. I also coated most of the exposed copper with new solder. Some of the big areas I sealed in with clear nail polish. Works perfectly now.

    The biggest takeaway i got from this is you really need to use a strong acid for corrosion. Vinegar's PH is not low enough to be effective with dealing with the very high PH of battery puke.

    #2 2 years ago

    Wow! Thanks for taking the time to post the tutorial. I learned something today.

    #3 2 years ago

    Thanks for sharing! I just tried some clean up with vinegar on a working board. Yeah, it didn't seem to do much, I may have to redo with this.

    #4 2 years ago

    Very interesting... I hope I never have to use this technique

    BTW. When you say "old wire brush"... can you clarify?

    Do you mean something like a small head soft-bristle brass brush?
    faz

    #5 2 years ago

    I would think that one of those Harbor Freight brass bristled "detail" brushes would be fine on something like this.

    Your method looks excellent! I'm going to have to try it out on the next corroded board I get. Half of the battle is getting the board and copper foil clean so you can desolder the old parts and solder in the new ones. This would sure speed things up and save more corroded boards from being tossed out.

    The toilet bowl cleaner says not to use on sinks. So how did you wash off the toilet bowl cleaner? Outside in the driveway with a garden hose?

    #6 2 years ago

    That's amazing Andrew, I did not expect the results to be THAT good. Heading out to Menard's today anyway, guess I'll be picking up a bottle.

    #7 2 years ago
    Quoted from KenLayton:

    I would think that one of those Harbor Freight brass bristled "detail" brushes would be fine on something like this.
    Your method looks excellent! I'm going to have to try it out on the next corroded board I get. Half of the battle is getting the board and copper foil clean so you can desolder the old parts and solder in the new ones. This would sure speed things up and save more corroded boards from being tossed out.
    The toilet bowl cleaner says not to use on sinks. So how did you wash off the toilet bowl cleaner? Outside in the driveway with a garden hose?

    I used a brush like one of these.

    https://www.menards.com/main/tools-hardware/power-tools-accessories/welding-soldering-equipment-accessories/tool-shop-reg-6-piece-wire-brush-set/p-1475648465494.htm

    I started inside, then went to some concrete outside that is already messed up. I did the scrubbing part inside in the sink. Some got on stainless steel sink and stained it bit. Probably best to do it all outside.

    I was quite surprised how well it worked. It did not damage the silk screen. Did strip some part markings, specially on the glass package caps and diodes. Did not eat away at fresh solder, but stripped off corroded solder until it was clean solder, clean copper, or in a few places the battery ate away the track completely. The ground track running up to U10 and U11 was open circuit in a few places, but would have gone open in an abrasive cleaning too. Made desoldering go much easier. Probably was easier on my desoldering iron too.

    #8 2 years ago

    Tried a corroded WMS System 4 board and got similar excellent results!

    This time i decided to do all the desoldering/clipping before the acid treatment.

    Pics start to finish. Got an action shot of the chemical reaction this time. Shot of the brush im using too
    20161012_170514 (resized).jpg
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    1 week later
    #9 2 years ago

    I just tried your new method on a Bally Evel Knievel MPU board. It works great!

    It really did speed up getting it cleaned up from the corrosion. It made a big difference.

    10
    #10 2 years ago

    I thought I'd give this a try on a few boards for experimentation purposes.

    WPC CPU #1, before
    WPC CPU #1, before

    WPC CPU #1, before
    WPC CPU #1, before

    WPC CPU #2, before
    WPC CPU #2, before

    WPC CPU #2, after
    WPC CPU #2, after

    Sys 3-7 Driver, before
    Sys 3-7 Driver, before

    Sys 3-7 Driver, after
    Sys 3-7 Driver, after

    Each board had 2 cycles, apply the cleaner, wait 5 minutes, brush aggressively with a brash brush. Rinse. Repeat.

    One thing to note - the acid won't permeate solder mask. And it seems like it won't eat traces.

    I think a good 2 step process would be 1) take a pass, rinse and dry, then 2) Clean any traces covered with solder mask with something to remove the solder mask, and then take another pass, rinse and dry.

    I think it could be a real time saver. Might make some boards that were previously thought unrepairable repairable.

    #11 2 years ago

    Excellent post! Like Ken said, the hardest part on super corroded boards is the ability to desolder badly affected components and solder back in new components on these boards that are pretty far gone. Definitely excited to try this method, I've got over 100 Bally MPUs in varying states of disrepair because of corrosion damage. Can't wait to try this!

    #12 2 years ago

    What seems good also with this method is a couple of cycles through this stuff, it's already "neutralizing" as it helps remove the gunk. So it's not like sanding where you then have to follow up with a vinegar bath.

    I'll have to try this too, worst case I'll have sparkly clean toilets in the house

    #13 2 years ago

    John:

    Your boards look pretty good in the "after" photos. However, the only thing I worry about is those WPC cpu boards have such tiny foil traces that I worry about needing to solder a bunch of jumper wires on the back of the board to restore trace continuity. As you know, much of the leakage damage is on the front side and in particular, underneath a couple of the ic's. Sometimes the trace is broken where the battery memory backup voltage can't make it. I fault Williams for designing such delicate traces on their boards.

    #14 2 years ago
    Quoted from KenLayton:

    John:
    Your boards look pretty good in the "after" photos. However, the only thing I worry about is those WPC cpu boards have such tiny foil traces that I worry about needing to solder a bunch of jumper wires on the back of the board to restore trace continuity. As you know, much of the leakage damage is on the front side and in particular, underneath a couple of the ic's. Sometimes the trace is broken where the battery memory backup voltage can't make it. I fault Williams for designing such delicate traces on their boards.

    Agreed. That's a distinct possibility, regardless of how you clean / repair WPC CPUs. I have not declared victory yet - but I also know that I find a lot of those traces under magnification before repair, and any I miss are generally pretty obvious by chasing a circuit out with the schematic to figure out why this row, or that direct switch, doesn't work.

    I think anyone who repairs as many boards as Andrew and I do have a pretty good sized stack of 'non repairable' boards that we save for trying 'new things' on. My intention is to rebuild these boards to work 100% - and probably seal one, and leave the other unsealed - to see if the damage returns. I have sealed every board I have done battery rework on for several years now - because no matter how carefully I believe a board was cleaned, it's cheap insurance - no oxygen should mean it can't corrode again?

    The cratex method I use on Sys3-7 boards is iffy on WPCs. Traces get blown away so easily with it, even with the least aggressive grit and being very careful. Fiberglass pencil sanding seems to give you more control - but is very time consuming. And you get painful splinters.

    There are days when I wish the price of repro WPC CPUs would drop a few bucks and put those of us doing rework out of that line of business. I can't keep up as it is.

    Which is why avenues like this have to be investigated. It's got real potential to save time, which in the end would mean saves money, and saves boards - but you can't really declare victory til you've rebuilt a few, and had them stay 'repaired' for some time now.

    I've kinda wondered what other acids might work, too. The toilet bowl cleaner is NOT harsh at all. I had a little splash on my skin. I did this outdoors. It had a nice 'wintergreen' scent to it - I certainly wouldn't huff it, but it didn't smell bad I used gloves and a garden hose to rinse when I was done.

    My new board repair shop (in progress) will have separate 'clean' and 'dirty' areas. This is something I would probably do in the 'dirty' area in a laundry tub style sink, as long as I can get appropriate ventilation in place. I sure wouldn't do it in my kitchen sink - I'd die a very slow and painful death if I tried

    #15 2 years ago
    Quoted from johnwartjr:

    I sure wouldn't do it in my kitchen sink - I'd die a very slow and painful death if I tried

    It's TOILET BOWL CLEANER. Do it in the toilet.

    #16 2 years ago
    Quoted from yendor0:

    It's TOILET BOWL CLEANER. Do it in the toilet.

    Ceramic sink works just fine too.

    #17 2 years ago
    Quoted from vdojaq:

    Ceramic sink works just fine too.

    I'd be concerned about the metal finish on the drain, though.

    1 month later
    #18 2 years ago
    Quoted from ForceFlow:

    I'd be concerned about the metal finish on the drain, though.

    What about it? I was just thinking about doing this in my laundry tub, since it just started snowing.

    #19 2 years ago
    Quoted from aobrien5:

    What about it? I was just thinking about doing this in my laundry tub, since it just started snowing.

    It may cause it to rust / tarnish. Quick exposure and if you keep water some water running damage is probably minimized. I have been doing it outside overtop of old cardboard.

    #20 2 years ago

    Excellent tutorial!

    Vinegar or Mustard is just about worthless when it comes to removing corrosion (because Mustard only has a ph of 5 compared to Snobowl's ph of 1). Your alkali that leaks from a battery is ph 13.

    I'm sure we all remember this thread, lol:

    https://pinside.com/pinball/forum/topic/terrybs-guide-to-repairing-battery-damage

    -

    You can rinse the boards off in a regular sink, just don't let any toilet cleaner glob sit in one spot for long. Once the cleaner has shot it's load, and you have diluted it with rinse water, it washes away without issue.

    #21 2 years ago

    I'm washing it off in the kitchen sink. Just keep the water running while you rinse everything off and you'll be fine.

    #22 2 years ago
    Quoted from yendor0:

    It's TOILET BOWL CLEANER. Do it in the toilet.

    I took this advice so the bathroom fan can ventilate!

    Edit: I'm not getting the bubbling like you show in your pictures at all. At least not until I start scrubbing.

    Edit 2: ok, so the bad spots took a few scrubbings but it looks pretty good!

    #23 2 years ago

    Yea my opinion was always the vinegar/mustard route was just making me feel better, and not really helping. (hence my post bomb in the Terry thread, which he got pretty upset at, and frankly, i probably should have not done.) But i stopped this technique a bit back. i have not tried the toilet bowl cleaner acid trick, so can't comment. but i can say this... maybe you guys moved the pendulum too far in the other direction?

    that is, if vinegar is ph 5, and snobol is ph 1, how about something in the ph 3 range?

    Just from the pictures, the snobol looks really invasive. i would be worried about long term issues that may take a while to arise. perhaps something with a ph 3 would be the "best of all worlds"? i mean the fact that you can burn the crap out of your sink/countertop/hands is a bit of a concern to me.

    for now i'm staying with bead blasting. i have a good feel for it, and no liquids are involved. (I really don't like using liquids on boards, it's a paranoid baseless feeling, but i can't get away from it.) Now if someone could test a ph 3 liquid and post here, that would be really great. It may be "enough" without being "too much".

    #24 2 years ago

    I'd guess that chrome finishes on faucets and drains would get damaged by the acid.

    You can buy gallon bottles of hydrochloric acid at Home Depot, Lowes or maybe Ace. In the Phoenix area they have a lot of it for all the pools out here. It's usually in the pool section of the store. For historical reasons it is labeled as Muriatic Acid.

    I throw this out there for anyone that wants to do a little research. Fill a shallow plastic tray with it and dip the whole board in. But I warn you not to breath in the concentrated fumes. It won't kill you, just make you gag. You need a well ventilated area with a fan. Even the fumes evaporating will make your skin start to itch. And don't store it near other chemicals, especially bleach.

    #25 2 years ago
    Quoted from JohnS:

    I'd guess that chrome finishes on faucets and drains would get damaged by the acid.

    If you add an oxidizer, it sure will.

    Take 3% Hydrogen Peroxide, and mix in some of your Muriatic Acid (2 ratio), THEN pour it on your stainless or chrome sink. Instant, permanent, black stains for your wife to enjoy!

    Quoted from JohnS:

    I throw this out there for anyone that wants to do a little research. Fill a shallow plastic tray with it and dip the whole board in. But I warn you not to breath in the concentrated fumes.

    The whole idea of the Snobowl is that the liquid is thick, so it does not run all over the board, into relays or under sockets. It's a very controlled process that you can do on location.

    If you want to REMOVE the copper from the board, again add an oxidizer to the muriatic acid and let her rip.

    Your acid/peroxide mix won't eat the copper protected by the green conformal coating, but any exposed copper will be completely removed in a few minutes (the warmer the temp, the faster the reaction).

    #26 2 years ago
    Quoted from vid1900:

    Your acid/peroxide mix won't eat the copper protected by the green conformal coating, but any exposed copper will be completely removed in a few minutes (the warmer the temp, the faster the reaction).

    Yup - exactly what we use for etching printed circuit boards....

    #27 2 years ago

    BTW: if you are mixing up some acid/peroxide to etch a board or something, remember AAA - Always Add Acid.

    You would pour the acid INTO the peroxide, never the other way around.

    -1
    #28 2 years ago

    I tried this on a couple junk MPU's. Found out that you can't soak them. It will melt all plastic parts on the board.

    #29 2 years ago
    Quoted from brenna98:

    I tried this on a couple junk MPU's. Found out that you can't soak them. It will melt all plastic parts on the board.

    Interesting! I've never heard of acid melting plastics.

    What parts melted? IC socket frames? Transistor casings? Nylon standoffs? Relay housings? The epoxy circuit board itself?

    We need pics of this for sure.

    #30 2 years ago

    Very impressed with this product. Started with vinegar, removed parts, then cleaned/scrubbed with Zep.

    image (resized).jpeg
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    1 month later
    #31 2 years ago

    Dont have this product where i live. But can i use bleach with ph1 and corrotion comes off??

    #32 2 years ago

    Bleach is ph 12, so that would actually make it worse.

    #33 2 years ago
    Quoted from DEN:

    Dont have this product where i live.

    I got it with Amazon Prime.

    #34 2 years ago

    Ph1. Isint that the strongest acid?
    Is that really what you use?

    #35 2 years ago

    Den, just look for a toilet bowl cleaner with acid.

    #36 2 years ago

    The main thing that needs to be understood here is that battery corrosion on these boards is:

    ALKALINE !!!! not acid.

    You need to use the OPPOSITE of alkaline to neutralise it - that means you need to use an:

    ACID !!! to neutralise the battery corrosion.

    #37 2 years ago

    In case this is helpful to anyone whose chemistry is a bit rusty.

    184phdiagram (resized).png

    #38 2 years ago

    Remember, these are called alkaline batteries: https://en.wikipedia.org/wiki/Alkaline_battery

    "Leaks

    Leaked alkaline battery
    Alkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation.[note 1] Risk of this can be reduced by not attempting to recharge disposable alkaline cells, not mixing different battery types in the same device, replacing all of the batteries at the same time, storing in a dry place, and removing batteries for storage of devices.

    All batteries gradually self-discharge (whether installed in a device or not) and dead batteries will eventually leak. Extremely high temperatures can also cause batteries to rupture and leak (such as in a car during summer).

    The reason for leaks is that as batteries discharge — either through usage or gradual self-discharge — the chemistry of the cells changes and some hydrogen gas is generated. This out-gassing increases pressure in the battery. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both. In addition, as the battery ages, its steel outer canister may gradually corrode or rust, which can further contribute to containment failure.

    Once a leak has formed due to corrosion of the outer steel shell, potassium hydroxide absorbs carbon dioxide from the air to form a feathery crystalline structure of potassium carbonate that grows and spreads out from the battery over time, following along metal electrodes to circuit boards where it commences oxidation of copper tracks and other components, leading to permanent circuitry damage.

    The leaking crystalline growths can also emerge from seams around battery covers to form a furry coating outside the device, that corrodes any objects in contact with the leaking device."

    #39 2 years ago

    The stuff that is forming crystals (and corrosion) is: potassium carbonate pH 11.5

    Screen Shot 2017-01-20 at 6.42.15 AM (resized).png

    #40 2 years ago

    184phdiagram (resized).png

    #41 2 years ago

    So in theory then I could use acid from a old car battery to clean alkaline damage off a circuit board?

    #42 2 years ago
    Quoted from Mitch:

    So in theory then I could use acid from a old car battery to clean alkaline damage off a circuit board?

    Yes, but sulfuric acid from a car battery is runny like water.

    The SnoBowl is thick gel that stays right where you put it.

    5 months later
    #43 1 year ago

    I went to the store today to buy some acidic toilet bowl cleaner and the only kind I could find with acid was this Lysol Brand. I don't know what % of acid it should be.
    Can anyone tell me if this will work ok?

    Edit: In case you can't see the ingredients, it says, 9.50% hydrochloric acid

    20170708_181421 (resized).jpg
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    #44 1 year ago

    If it's fizzing, it's working.

    (and it will kill 99% of all of your viruses too)

    #45 1 year ago
    Quoted from vid1900:

    If it's fizzing, it's working.
    (and it will kill 99% of all of your viruses too)

    Yes it did fizz some but not like crazy. I put it on and rinsed twice, this is the results.
    Because I don't have experience in circuit board repair I am going to try it without replacing the sockets.
    it may have already been mentioned, but is there a good way to clean out the pin holes in the sockets? looks like there is still a little crud in some of the holes.
    does it look like it cleaned up good enough to try?

    cpuboard2 (resized).jpg

    cpuboard1 (resized).jpg

    cpuboard (resized).jpg

    #46 1 year ago

    Those sockets are destroyed. They must be replaced. Send it out if you are not experienced enough to do it without trace damage.

    #47 1 year ago

    Yeh those sockets are shot. There's no fixing them and should be replaced.

    #48 1 year ago
    Quoted from KenLayton:

    Yeh those sockets are shot. There's no fixing them and should be replaced.

    There is an Ebayer who goes by "Classicgameparts" and has posted an ad for Williams System 3 combo repair to refurbish the CPU, driver board and power supply for $235.00 plus $14.50 shipping.
    Have you ever heard of this guy or know anybody that has used his services?
    Also, wondering if there are hidden charges that will be applied once he has the boards?

    #49 1 year ago

    Also, I cleaned up the 40 pin connector on the driver board and thought it cleaned up pretty nice and would probably be ok until I started looking at more closely after I cleaned it...I guess I broke off about 3 of the female connectors while I was cleaning it with the bowl cleaner and a soft wire brush.

    connecor1 (resized).jpg

    connector (resized).jpg

    #50 1 year ago

    what adds to your problem is that the IC sockets have been replaced once before the battery leaked. people that work on these boards very often know what the expect from the factory soldered stuff. adding the unknown socket rework quality and then battery damage on top of that makes it really sketchy .

    *edit*

    2nd look at your pictures.... while you have removed the corrosion, your interconnect is still damaged. The connector plating has been stripped off. Need replaced.

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