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I'm trying to get rid of the flux on my board but it seems I have a problem. this is my board:

figure1

figure2

After soldering two memory under the board(as you can see two memory(a RAM and a Flash)), there is a bit flux among the pins and unfortunately under the plastic of the pin-headers. I have used a spray to wash it out but it doesn't good work for me. and I used a combo 50-50% alcohol and acetone but still...nothing!

Yesterday I was thinking that maybe boil water could help me. then I googled this "wash PCB with boiling water" and the first result was this. if you take a look in that page, you will see this comment:

Never use water soluble unless you are using a dishwasher to clean the boards. Found that out the hard way at a job years ago. Hot water is the only thing that will clean the flux off, not even alcohol. If you don’t clean it off the flux will eat at the solder connections turning them black and even chew through small leads. No clean is the way to go with a simple flux remover.

Ok, then this approach will work. but I have a few questions:

  1. Do you have any experince with this approach?
  2. Can boil water damage the PCB of the board? or some metal parts? and or some components like electrolytic capacitor?
  3. If in your opinion this is a good approach, How would you do it? for example, maybe this would be silly but I was thinking to put whole of the board inside of a bucket full of boil water and then shuck the board.
Roh
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    Sounds like a bad idea to me. What kind of flux are you using? – Matt Young Jan 04 '15 at 16:14
  • @MattYoung Thanks Matt. Do you mean it is soluble in water or not? if so, I'm not sure. this is the brand of it: http://upload.tehran98.com/upme/uploads/e4c95db3b962599e1.jpg – Roh Jan 04 '15 at 16:18
  • I would start by getting some different paste. A paste that doesn't even say what type of flux it uses is questionable at best. – Matt Young Jan 04 '15 at 16:23
  • If you used rosin flux, then there is no problem. If you used water-soluable flux, then try cleaning carefully with clean water. Then next time use rosin flux. – Olin Lathrop Jan 04 '15 at 16:30
  • @MattYoung Dude, I'm trying to figure out the current problem. I promise you to use a better flux in the future, if I could find a solution. – Roh Jan 04 '15 at 16:34
  • @OlinLathrop Thanks uncle Olin. ok, next time I will use rosin flux. also I hope I could find this kind of flux in my f**king country. I don't know why I'm living in Iran. – Roh Jan 04 '15 at 16:38
  • @OlinLathrop Excuse me, may I ask a question? Why should I be careful if my flux would be water-soluable? – Roh Jan 04 '15 at 16:47
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    Rosin flux is usually the most available. The problem with water-soluable flux is that it must be carefully cleaned off. Residue attracts moisture from the air and becomes conductive. I once saw a reset line pulled low with only a few 100 Ohms by water-soluable flux under a QFN package. Removing the package, cleaning the board, then resoldering with rosin flux fixed it. – Olin Lathrop Jan 04 '15 at 16:50
  • @OlinLathrop +1 for perfect answer. – Roh Jan 04 '15 at 16:54
  • Is the flux causing any problems? You can leave rosin flux on a board. (Doesn't look all that great but it will work fine.) Find out what kind of flux you have and how it should be cleaned. (do you also have a flux cored solder?) – George Herold Jan 04 '15 at 17:06
  • You can leave the board with flux as long as it is a NoClean flux. Other fluxes will eat away your board. – Gilad Jan 04 '15 at 18:26
  • @GeorgeHerold Yeah, I cannot erase or program my MCU. Thanks. – Roh Jan 06 '15 at 15:38

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Do youself a favor and get 1 gallon of flux remover. You can reuse it over and over again and as far as I know lasts for a very long time. Costs around $75

Gilad
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