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Cleaning boards after working on them advice please

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  • Cleaning boards after working on them advice please

    Some boards that come with no water damage for repair leave a little dirty from the flux used on them, regardless of a good cleaning with 99% alcohol and a brush I can still see that someone worked on the board and did not clean it well.

    I have a Crest and Branson EC cleaner and have watched Louis video on how to use it, but that is for water damage boards, I want to just clean them fast to make sure the work we did looks decent.

    Thanks in advanced!

  • #2
    Use ultrasonic machine when you suppose to have corrosion underneath BGA chips.
    Or when the board is affected on large areas.
    To remove flux from small area, always better toothbrush.
    Heat a bit corresponding area and flux go away more easy.

    Be aware of using UC; no sweep function can generate more damage on the board.


    • #3
      I use UC on anything with too much flux or corrosion. If it's a simple job like a PPBUS tantalum cap, I just be cautious of the amount of flux I use, and I use alcohol and a paper towel to clean it.


      • #4
        What I do is a little unorthodox but it works quite well. If there is corrosion I bush it with vinegar and a wetting agent (soap) using a micro glass fiber brush to clean surface corrosion. Some times if it is bad I will let the vinegar / soap solution stay on he board for 5-10 minutes before power washing.. Then I take it to my sink and power wash it with a water pick. I use warm water and soap and blast under all the BGA packages. Even the CPU / Ram and SMC. Then I rise with warm water. Last I use my air compressor to blast all the water off the board and blow under the BGA packages, plugs etc. I even wash the CPU fans on the board to get the crud out this same way. Some times i will use hot air to finish it off but usually I don't. Often the board is in / out in under 10 minutes and I have it back in the machine testing it.

        I have considered getting a large ultra sonic and probably should but this works every time. The Ultrasonic I have is too small for MacBook boards so when I started working on them I improvised this process. It has worked so well I have not got around to buying a bigger Ultrasonic.

        One of my customers tries to fix the MacBooks before sending them to me and uses a ultra sonic to clean their boards. Usually what I do comes out better. Just depends on the corrosion.

        Lots of ways to do the same thing. I am sure I will get flamed for doing it this way but it works for me. I fix about 10 machines a day and 2-3 end up needing aggressive cleaning.

        Micro-Fiber towels are my best friend! I buy a large pack every so often at CostCo and use them to soak up alcahol after I clean with the micro fiber glass brush. You can't tell where the flux was and they come out great. Once my towels are dirty I just wash them in the laundry. Some times I throw the nasty ones away but usually I just keep washing and reusing them. The fresh nice ones I save for screen cleaning etc. The nasty ones get demoted to flux cleanup. I don't use consumables such as paper towels or swabs.

        I have had been given nasty boards that were literally coated in flux. For those I will just wet the micro fiber towel with Alchol directly and wipe the board clean. Works great! I can't live without a micro fiber towel.
        Last edited by KC Micro Tronix; 2 weeks ago.


        • #5
          Thanks for all the tips, I already have the Ultrasonic Cleaner and I only want to clean boards that had lot of work done on them, JohnB8812 how long do you put it on the UC for and how do you dry it?


          • #6
            I usually put them in the cleaner for 2 minutes on each side then use alcohol to displace the distilled water. Put back in for two minutes then dry with alcohol and heat. I use compressed air to blow out anything under the big BGA chips CPU/GPU/RAM, etc. Usually leaves minimal streaks and looks good. I do a final go over with alcohol and a paper towel for anything I miss.


            • #7
              JohnB8812 Thanks, that sounds good, will try later with a board that looks a little nasty after working on it.


              • #8
                CLR+ light scrubbing. Dishwasher! Straight Methanol removes water perfectly. I own a great ultrasonic cleaner. I use it sparingly. Selectively. MEK is a great solvent!! HELLO! If the State of California bans it: it works and you need it. Cyanide vapors, Freon vapors..Carbon Tetrachloride...mmmmmm....There are dangerous chemicals that do the best job. Your dishwasher is made to clean stuff and not leave spots. hmm. Would you believe that your dishwasher is the BEST ever??!! A good ultrasonic cleaner will eat away at the end caps of SMD components like resistors, mlcc caps, etc. If corrosion has already eaten most of it away: ultrasonic cleaner should be your last choice.


                • #9
                  Ok great, lots of info here and I agree on UC damaging boards, I already had one like that, but my problem was that I left the boards a little too long, I have a small boat that I had to do some repairs on it and had to use MEK, I will try that too before putting them on the UC, I was afraid that will damage some parts as that is a pretty strong solvent, but I have seen a few people use it on boards now.


                  • #10
                    If no sweep function available, change board position every 20-30s, to avoid hot spots; just push it 1-2cm.
                    Of course, depending of corrosion state, change board side up-down every 2-5min.


                    • #11
                      Thanks for al the tips, in the case of just cleaning flux from a clean board after doing some work I think it makes no sense to clean it on a ultrasonic cleaner and do all that extra work just to ensure the board leaves the shop looking like new, what I just discovered is that if I use 3M Quick Dry Contact Cleaner 16-102 and a brush to clean the edges of the chips as well as clean room wipers at the end the board looks like nothing happened and it takes me no more than 1-2 minutes to clean it well. Hope all this helps someone later on.


                      • #12
                        The dish washer is a great idea if I wasn't in a hurry. I guess I wont bother getting a ultra sonic machine. I have one for phones but it is crazy small


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