How do you remove acid corrosion from pcb with components?

Discussion in 'The Projects Forum' started by bigcape, Sep 21, 2009.

  1. bigcape

    bigcape Thread Starter Member

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    Hi everybody! I am VERY new and self-teaching myself. Be gentle!

    I have found a few little gizmos that do dot work because the batteries have been leaking for several years. (AA 1.5V Alkaline, Pile Alcaline)

    The challenge for me is to repair them if nothing else for the "Cool I am learning this stuff" factor.

    :confused: Is there a liquid you guys use to possibly brush on a PCB board WITH components (trimmers, resistors, diodes) that will eat the corrosion but not damage the components then blow off with compressed air (possibly)? :confused:

    In particular----there is this one trimmer that I know i will not be able to replace because I believe it was custom made into a side thumb wheel. It is supposed to be a 5k trimmer but it is reading 5-15 MEGA-Ω due to the resistance the corrosion is causing.

    Corrosion will cause increased resistance right?

    Thanks and "HI!" to all.

    There is so much to learn that is WAYYYYY over my head.

    :confused: Also, I need a referral to a tutorial on how to turn a schematic into a working circuit or project.:confused:

    I know all the symbols and understand the concepts but I'm having difficulty figuring out the order of flow especially when 2 or more components appear to be connected wih each other as to not blow something.:eek:

    I hope it is okay that I "Hi-Jacked" my own thread!
    Sean
  2. studiot

    studiot E-book Developer

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    Fairy Liquid, a toothbrush, warm water and elbow grease work wonders.

    Allow the equipment to drain and air dry thoroughly afterwards 1- 2 days.

    Corrosion will not increase the resistance of any component connected in parallel to the corrosion. So the resistance of your pot will only increase if the corrosion is causing bad contact between the wiper and the track. the track should remain at 5k.

    Good experimenting with your new hobby.
  3. jpanhalt

    jpanhalt E-book Developer

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    What is "Fairy Liquid?" My guess is that is a general surfactant, like 409 Cleaner in the USA. Be sure to rinse well with water afterward. If you want to speed drying, rinse with 50% or so isopropyl alcohol, then pure isopropyl alcohol. The intermediate step helps to dissolve the water.

    You can remove corrosion, but that will not renew the surface that is left.

    As for circuit building, look up "schematic capture." Bill Marsden on this forum has some nice hints in his blogs. Another term to look up is bread boarding.

    John
  4. bigcape

    bigcape Thread Starter Member

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    "Fairy liquid"? for a bit I thought I was being poked fun at!

    409 in a spray bottle? For real? When I was a kid i set a bottle on the hood of my parents car and it ate the paint. Wouldnt that ruin all the markings on a PCB

    I was hoping for something like jewlery cleaner that would leave things nice and polished like when you pur Coca-Cola on the terminals of a car battery.

    Hey John,
    Thats the problem Ive been bread boarding but I cant tell from schematics the "trace" for lack of better description of the flow in case "multi- connected components" have to before or after.

    I read a thread http://www.allaboutcircuits.com/vol_1/chpt_7/3.html on making copmlicated circuts with resistors and caps on here make sence buuuut I NEVER would have gotten what they got. That would mean "it wouldnt work!"

    Are you telling me to just "google it"
  5. SgtWookie

    SgtWookie Expert

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    I think that Dawn dishwashing detergent is the USA equivalent of the UK's "Fairy Liquid"
  6. studiot

    studiot E-book Developer

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    Yes it's washing up liquid.

    The industrial equivalent is called 'Teepol'.

    I recommend patience, rather than alcohol. Water can get inside many things and thin films will not be displaced by alcohol if held by surface tension.
  7. bigcape

    bigcape Thread Starter Member

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    Okay so I was being poked fun at........ DISHWASHING LIQUID does NOT remove oxidation!

    Corrosion IS OXIDATION!

    Corrosion involves the deterioration of a material as it reacts with its environment. Corrosion is the primary means by which metals deteriorate. Corrosion literally consumes the material reducing load carrying capability and causing stress concentrations. Corrosion is often a major part of maintenance cost and corrosion prevention is vital in many designs. Corrosion is not expressed in terms of a design property value like other properties but rather in more qualitative terms such as a material is immune, resistant, susceptible or very susceptible to corrosion.
    [SIZE=-2][/SIZE]​

    The corrosion process is usually electrochemical in nature, having the essential features of a battery.

    Corrosion involve two chemical processes…oxidation and reduction. Oxidation is the process of stripping electrons from an atom and reduction occurs when an electron is added to an atom. The oxidation process takes place at an area known as the anode. At the anode, positively charged atoms leave the solid surface and enter into an electrolyte as ions. The ions leave their corresponding negative charge in the form of electrons in the metal which travel to the location of the cathode through a conductive path. At the cathode, the corresponding reduction reaction takes place and consumes the free electrons.




    I'm not feeling the luv here!
  8. jpanhalt

    jpanhalt E-book Developer

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    409 and the original Fantastic appear to be ethylene glycol-type cleaners. They may have methyl ether modifications (e.g., glyme) to help dissolve oils and greases, and they have added surfactants. They are not particularly strong solvents, and they will not affect cured enamel paints with short exposure times. They will not remove the markings on a PCB. Frankly, I would just go with pure water or water with a little detergent (few drops per 6 oz.) Dawn is fine; I would use Cheer Free...I don't like the smell of Dawn.

    Some jewelry cleaner is ammoniated; older cleaners contained cyanide. The cyanide was a great cleaner, but was bad for depressed jewelers. Their purpose, though, is quite different from removing corrosion and salt deposits from old batteries.

    I don't understand that question.

    Not at all. Google is just an alternative. As I mentioned, Bill Marsden and AAC provide many helpful resources here.

    Do you want to convert schematics to PCBs?

    If so, that is where schematic capture comes into play. I use Eagle, which is available as a free version.

    John
  9. beenthere

    beenthere Retired Moderator

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    While you are correct that
    you might note that
    The scrubbing is effective. More so when you add some baking soda as an abrasive and acid neutralizer.

    Removing crud takes some effort. The copper traces and component leads that have corroded away do not come back, so removing the corrosion does not necessarily restore the circuit.

    You may be able to see it clearly enough to make a schematic, though.
  10. bigcape

    bigcape Thread Starter Member

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    The copper traces are in good shape its some of the wires and pots that are bad.

    A corroded wire WILL have much higher resistance for certain!

    Just like with an OXIDIZED soldering tip you will burn up the component BEFORE the solder melts!

    I cant do any repairs untill I get the crap off!

    Also, what gets the epoxy stuff off to even get to some of the solder welds?
  11. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    You beat me to the baking soda, which will neutralize acids. Not to sure about alkalyne though, but it is a decent cleaner in any case. The main thing to remember is you're cleaning a chemical off the board first, neutralizing the acid second. Get all the acid off (or whatever) you don't need to neutralize what's left.

    A rough grit cleaner works for contacts in battery cases by exposing fresh metal. There are risks with this (aren't there always?) in that many cases the steel spring is coated with something more corrosion resistant, but we are talking a senario where the damage is done.

    You can't really remove the oxide chemically, this leaves mechanical methods (ie, elbow grease) or pick tools. I'll make an exception to that, flux. Flux will help some with parts that are old and oxidized.
  12. bigcape

    bigcape Thread Starter Member

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    I want to take a schematic (project) I find in a book or online and make it a working thinggy!

    That would include turning it into a PCB.

    There is all kinds of cool stuff to build out there i have come across.

    Project kits are like connecting the dots in kids books! Besides all the really neat stuff doesnt come in a kit!

    I just started but I have a natural ability to solder right off the bat!

    Connecting the dots (so-to-speak) from a schematic to a working circuit is giving me HELL!:confused::mad:

    I get lost, confused, and a roaring headache!
  13. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    We have a good experiments section in our AAC book, look at the top of this page.

    I've been working on my own set of experiments that will eventually wind up there.

    The 555 Projects
  14. jpanhalt

    jpanhalt E-book Developer

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    What specific type of help are you looking for? Try aspirin or acetaminophen for the headache.

    That is a very rash conclusion and is certainly inconsistent with the number of helpful responses you have gotten to a poorly articulated problem.

    John
  15. bigcape

    bigcape Thread Starter Member

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    Hi Bill,

    I've read good things about you.

    Forgive the newness I possess at this time.

    I just cant escape the logic of all the sterling silver that with one wipe is no longer lacks luster. And the Car battery terminals that look brand new after pouring Coca-Cola on them.

    If I didnt think that would ruin a PCB and components I'd open a can a pop and share it with my broke project!

    Hmmm wait a min.... lemme ask you. If there is no power and all caps are discharged. is a circuit with diodes, caps, I.C's etc. as long as there were NO MOVING parts or FABRIC's like a speaker, waterproof?
  16. bigcape

    bigcape Thread Starter Member

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    "poorly articulated"?

    Jeeze John, if I have offended you I am sorry.

    I do not know what was so confusing about asking if there was a solution thats eats away oxidation/ corrosion from a circut that has had the batteries leak all over the place!

    Im trying to do a mini "restoration" per se.

    Forgive me if I thought i was being teased about DISHWASHING SOAP> because I CLEARLY WAS!

    Im a great sport so I can/could take it!


    Oh.... and my comment about "not feeling the LUV" was in jest NOT rash as you pointed out........ THATS WHY I SPELLED THAT WAY!


    please ACCEPT my BLANKET APOLLOGIES to everyone that my "tone" of the written word could not be felt.

    Oh telling me to take an asprin was plain rude.

    Why don't you re-read my FIRST POST AND OPENING STATEMENT that says:

    "Hi everybody! I am VERY new and self-teaching myself. Be gentle!"
    Last edited: Sep 21, 2009
  17. jpanhalt

    jpanhalt E-book Developer

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    You were not being teased about the soap. It's a surfactant. Everyone suggested water or water plus surfactant PLUS elbow grease as the best answer.

    The magic dips for silver probably will not work. They are based on the solubility of the silver oxides/silver sulfides. Unless your PCB is silver, that is irrelevant. Moreover, a shiny PCB trace does nothing for conductivity.

    We were referring to removing the crud left from the battery. Try Coke, if you think it will work. Remember, though, the chemistry of a lead-acid battery is different from that of a non-rechargeable battery. The acid in Coke will affect galvanized coatings, if there are any.

    John
  18. bigcape

    bigcape Thread Starter Member

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    Well, I guess Im just to new for this forum. I will read and not post.

    Thanks for the gavanized warning.

    "shiny" I meant was for the solder joints its an indicator that the OXIDATION might be GONE???

    "elbow-grease" I am new so everything looks VERY delicate to me.

    Like I said I will read more instead.
  19. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    With chemical compounds you never know what you're getting. Many will leave conductive paths, which has effectively distroyed your board. The other side is many parts are not waterproof, though most are. A common technique is to clean a board in water, then let it dry in a warm place for a day or two, maybe more. I've saved pagers and cell phones that way after toilet treatments and being in the laundry. I don't recommend it, but sometimes you get lucky.

    As to laying out board the only real cure for what ails you is practice and experience. When I draw a schematic that I plan on building (or even thinking about it) I make sure I include the pin numbers of all the chips.

    I think you are looking for an easy answer for the acid problem. From the number of replies you probably have figured out there isn't any.
  20. bigcape

    bigcape Thread Starter Member

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    Your right Bill thats why I gave up! Either that not to many folks here do repair work.

    I kinda figured as many electronic items get leaky batteries there had to something out there.

    I cant desolder with this oxidation either! I dont want to overheat the components.

    Oh-well im going to have to find a Chemistry Forum and challenge those boys.... then market and sell it!
    Last edited: Sep 21, 2009
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