Modding

Discussion in 'General Electronics Chat' started by R!f@@, Aug 16, 2010.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    I wonder how many of you have these problems, and who has actually done anything to rectify it.

    In my case, being a salty environment, not to mention the dust accumulation, I have had a lot of issues regarding copper tracks and exposed solder joints forming oxidization.

    PC components being expensive and very effective in collecting dust, especially the expansion cards like graphics and sound cards, I have had bad experience about card failures due to salty dust collecting on top side of the cards ( side facing upwards ).

    Cleaning is not effective once the degrading had started. Not to mention the unavailability of cleaning agents that are effective in removing the oxides and dust.

    Since I am assembling my new workstation, ( the components have been bought for quite a while now ), I have been thinking before assembling I have to do something quite effective for this problem.

    Since I have high temp resin compound which is used to encase electronics, I thought of an idea. But to make sure I do not destroy an expensive graphic cards and such, I have to test using another working card. Going through my junk I found the one below.

    Which is quite clean but has started to rust somewhat. Card is assumed to be working since I do not throw away any working ones. It was a left over from my current upgrades to Audigy ZS.

    [​IMG]

    [​IMG]

    You can see the dust accumulation.

    All I need to protect is the top side. Which is always the side collecting dust.

    After a thorough cleaning using thinner the card is prepared as below

    You can see what I did to prevent the resin from dipping from the sides.

    [​IMG]

    [​IMG]

    The side are enclosed by plastic I found lying around and is held by super glue and wood glue is used to seal the side from leaking.

    Now the resin has been applied and left to dry. We'll see after it had dried.
    Till then
    :p
    Cheers
     
    Last edited: Aug 17, 2010
  2. tom66

    Senior Member

    May 9, 2009
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    As this salt is corrosive, does it not affect the other components in your system? Motherboard, HDD, power supply? Even though the solder joints aren't exposed on many of these devices, wouldn't surface mount components suffer?
     
  3. sceadwian

    New Member

    Jun 1, 2009
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    If the external environment is corrosive the solution is simple.
    COMPLETELY seal the internal and external environments air tight, use proper heat sinks (assuming an oxidized surface) and go from there.

    For many systems all you'd need is some good caulking, high velocity fans and generous surface area of anything external to the system that could act as a heatsink.
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Simply using a conformal coating spray on the circuit boards and also rearranging the fan scheme of your case to create a slightly pressurized case can do ALOT to avoid dust/salt contamination issues. Not sure how your resin coating is going to effect the thermal conductivity/radiation of the circuit board.. I would apply it very lightly. or do it right with a proper conformal coating spray. Or go all out and just sink the computer into transformer oil.
     
  5. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Here are the resin coating.

    [​IMG]

    [​IMG]

    I have sealed the upper side which is prone to dust collection
    One thing I did not assumed was shown below

    [​IMG]

    The resin has seeped through the through holes. I did a boo boo when I cleaned the surface
    I did not clean the component side and the resin has hardened with the accumulated dust in between the IC pins :eek:.

    Now to test it.
    Will be back later
     
  6. R!f@@

    Thread Starter AAC Fanatic!

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    One question though.
    Would the resin create problem in high end graphics, since they operate at high speed. Any deposit between solder joints might create stray capacitance that might be high enuf to slow down clock.

    What do you guys think?
     
  7. mcgyvr

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    Again I think the resin is a BAD idea.. Simply apply a conformal coating spray. Much easier to apply too.
     
  8. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Somethings you guys don't understand is getting the spays all of you suggest is hard for me. I have to buy them online and it takes a lot of money to ship somethings to Maldives.
    Unless I have a good paying project I cannot buy such things.
    I bought these resin for a job I did. When I buy, I buy plenty.

    I will ask around when it is time to buy some since a project is on it's way soon I hope. :)
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    I'm afraid I'll have to agree with mcgyvr; conformal coat is the way to go.

    In the highly corrosive environment where you reside, anything that is not protected with conformal coat will shortly be eaten up. That's great for your business, but terrible from a reliability standpoint.

    Believe it or not, hand sanitizer works pretty well in conjunction with a short-bristled nylon brush (think rolled-metal-handle black-nylon-bristle acid brushes with the bristles trimmed short) to remove most of it.

    Isopropyl alcohol will help to remove the remaining residue. Use the purest isopropyl that you can get; be warned that it will absorb moisture out of the atmosphere if left open.

    Conformal coat is by far the most preferable material to use, as it is electrically neutral while providing a good seal against the environment. Try to avoid getting it on heat sinks, as it will somewhat insulate them from providing the necessary cooling.

    If you can't get conformal coat economically, you could try experimenting with clear acrylic lacquer spray. This is less than ideal, as the electrical properties are unknown. However, if it turns out to be viable, you might save money and extend the life of the electronics at the same time.
     
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  10. mcgyvr

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    R!F@@, you really could have used some conformal coating for those gas pump control boards from a while back.. (I think that was you)
    Also don't understand how you can get all the electronics components you need to fix things but cannot get conformal coating??

    But yes I have also seen clear acrylic lacquer spray paint used too.
     
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  11. R!f@@

    Thread Starter AAC Fanatic!

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    Thanks Sgt and mcgyvr too for ur opinions. It's not the first time that all of you have mentioned about conformal coating.
    And I guess it is about time that I get it. rather doing what I did.
    below is a link. Is this what u all are talking about.

    http://shop.ebay.co.uk/i.html?LH_PrefLoc=1&_nkw=conformal coating&_fln=1&_trksid=p3286.c0.m283

    and yes, it was I who deals with the pumps.
    That reminds me, I need to update that thread. I remember saying something funny happened about that pump. The pump works though.
     
  12. mcgyvr

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    yes thats the stuff..
     
  13. sceadwian

    New Member

    Jun 1, 2009
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    I think trying to conformal coat a system to this degree is not practical in the slightest, there are MUCH better ways of doing it as I mentioned. A simple sanity check should tell you that the first thing you should do is simply build the system in an enclosed air and water tight cabinet to remove it completely from the environment and use a heat pump such as a water base system (cheap nowdays) to remove heat from inside the case. If you can buy a water/gas tight aluminum enclosure your problems are pretty much solved, you just have to turn the ouside of the case into a heatsink and circulate air rapidly inside of it. Cords going outside the cabinet are easy to seal.
     
  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    I think it was a great idea. You are actually doing something to improve life for yourself and your island-mates.

    I applaud your attempt.

    You may consider a lighter coating next time. You may also be able to thin out the mix a little and make a "spray-on" or "brush-on" coating.

    It would be very expensive to take standard off-the-shelf computer accessories/peripherals and build new heat-sunk, air-tight boxes for it all when a few cents of chemical coating and some elbow grease is all you need.

    I would recommend following the conformal coating line of thinking. Buy bulk and offer it as a service.

    It would be better to coat them BEFORE too much has gotten to them You may want to pack them in desiccant for a while before coating them also. Else you are just sealing in the contaminants. They will continue to eat away at the parts INSIDE the potting.

    But, im sure you have enough junk-box parts to try different things on.

    You may want to look around for a DIY or home-rolled coating recipe on-line. There are many people with the same problem as you, and someone may have come up with a brilliant way of dealing with it that doesn't involve building a test chamber for every piece of electronics you wish to buy.
     
  15. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    lets see..
    Option 1
    1 or 2 cans of conformal coating=cheap and highly effective

    Option 2
    water/gas tight enclosure, heat pump system, multiple heat sinks. Not to mention that a closed system like this is a thermal nightmare. = probably more money that he has in his whole computer.

    Which one isn't practical again... Pretty clear to me.

    Sceadwian, Close off all the ventillation holes on your computer, including power supply vents,etc... everything..Even just for a few minutes.. You'd be amazed at the increase in temperature inside that case. You expect someone to add an overly complex water cooling system for the processor, north/south bridges, graphics cards and the power supply... over simply applying a conformal coating spray.. thats silly.
     
  16. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Conformal coating sounds like the best suggestion so far. I would not thin the liquid coating more than say 10% or so, as that could greatly change its film strength to the point that it will pull away from the sharp solder points. Thus, not do its job.

    In looking at the pictures, though, I am not convinced it is corrosion. Some possibilities to consider are dust (as originally stated by Rifaa), corrosion (filiform?), mold, or chemical etching of the solder mask.

    Consider these two sections from what was posted. First , notice the sparing of certain areas, notably near the board edge connector.

    [​IMG]
    Perhaps whatever is used to clean the boards after manufacture or residue from a no-clean flux pools around the solder joints, absorbs moisture, becomes a little sticky so contaminants adhere, and gives the dull areas seen here. The spared areas were just cleaned and/or dried better than the other areas.

    Second, consider areas where the dullness is apparent and is not around any particular solder joint.

    [​IMG]

    Left over flux or cleaning agent could do those things, as could mold. But I have a hard time seeing how corrosion could do that in the open spaces.

    I am a lab rat, so am prone to experimentation and questions.

    1) When you look at a new board without these blemishes, is it shiny everywhere, or are there dull spots that eventually become these blemishes?

    2) It looks like most of the blemish is on top of the solder mask. That might argue against corrosion. After cleaning, there is still dullness in the originally blemished areas. Is the solder mask pitted?

    3) How fast do the blemishes form on a new board? Once you simply clean the board, do they re-form?

    4) Don't rule out the potential for mold/mildew. The solder mask is organic and those bugs can eat anything organic, including any new conformal coating you add.

    5) If it is just dust hanging up on high spots, I am not so sure a conformal coating will do any good.

    The number of experiments you can do is huge, and your time is limited.

    You might consider:

    1) Conformal coat 1/2 of a new board; then just thoroughly clean the other half (isopropyl alcohol is a good choice). Dry it after cleaning. Put into service and see what happens.

    2) Take one of your affected boards, clean it, and then do like in #1.

    3) If you have a microscope or have access to a clinical laboratory, take a tape impression of the blemish. Clear Scotch tape works fine. Press the sticky side to the blemish, then remove and observe. You can also use that technique to transfer to a culture plate. Any clinical microbiology lab will be able to do that for you.

    Good luck,

    John
     
  17. t06afre

    AAC Fanatic!

    May 11, 2009
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    If corrosion is the problem, should it not have been more verdigris on the bronze connectors?
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
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    What ever happened to good old polyurethane varnish? Tough as nails and also available in a spray can.

    On any of these products it will obviously have to be non-conductve, but you'll also want something with a low dielectric content so capacitive coupling between long, close traces doesn't present a potential problem.
     
  19. jpanhalt

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    Acrylic resins used in conformal coatings with which I am familiar can be soldered through. They are essentially lacquers and can also be removed with solvent. I doubt that polyurethane varnish would allow such easy repair.

    John
     
  20. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    OK..Guys.
    As usual u guys are making my head spin. I ask to find and what I get is confusion.
    Now I do not have an access to a lab and time. Not a bad thing though but too many options to choose by no experience.

    The link I showed had different brands, all conformal coating. 3M, RS and such.

    I like to get a pick from u who have used it. It should be able to be used on high end graphics and mobo's where the coating should not interfere with the device operation. So to say, High electrical insulation and a better coating to prevent oxides forming due to dust and such. I will be coating new boards, so previous oxides won't be there.

    So give me pick from the link if it is not too much .
    Thanks again
     
    Last edited: Aug 18, 2010
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