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deplanche
05-19-2008, 08:27 AM
I have watched a few How-to's on soldering and read a few articles, and am totally confused on how to clean the back of the PCBs when I am done. I am not sure if I should be using soap and water, alcohol, a special cleaner, or just leaving it. Any suggestions?

Since I know it will come up, I am using solder from radio shack, that i think is 60/40 flux core. There aren't any instructions for cleaning on the package, so I am not sure what to do.

Macrosill
05-19-2008, 08:30 AM
I would not use soap and water as you risk ruining your circuits by getting the components on the other side all wet. Water also causes corrosion. There is a special cleaner you can get in a aerosol can that is made to clean off the flux. Personally I just leave it as is and do not clean it off, I probably should though.

Penfold
05-19-2008, 09:35 AM
I have used a toothbrush and alcohol (Iso 91%) and gently brushed the joints. It seems to work well. after all that I take a blow dryer and dry off the board. Just remember to keep moving and not stay in one place as you can melt stuff if you are not too careful. Also, don't get to close with the blow dryer, about one and a half to two feet should do it.

These may not be the best practices, but they have worked for me.

rlilly
05-19-2008, 10:03 AM
I use a product called 'Flux Off'. You can find it at electric supply stores. I'm not sure what's in it, but it makes the back of those boards sparkle!

tonypgst
05-19-2008, 11:16 AM
I have used a toothbrush and alcohol (Iso 91%) and gently brushed the joints. It seems to work well. after all that I take a blow dryer and dry off the board. Just remember to keep moving and not stay in one place as you can melt stuff if you are not too careful. Also, don't get to close with the blow dryer, about one and a half to two feet should do it.

These may not be the best practices, but they have worked for me.

This is the method I use, although I don't blow dry, just air dry. At most, I'll use a lint free cloth to help with the drying.

I miss the board washer and dryer oven we had when I was stationed with a mobile unit in the Navy. When we would come back from depolyment, much of our gear was broken down and cleaned. I put many circuit boards through the washer and dryer. An RODI filter and special cleaning solution is a must for washing boards with components, blow dry with compressed air, then a low temperature bake for 24 hours and boards sparkled. :) I was always amazed that we never experienced a failure from servicing our equipment in this fashion. Scary, but it beat leaving dust and dirt in everything after operating in open fields or tent citys.

omzig
05-19-2008, 12:09 PM
Over the years I have heard many different opinions on this subject. Allegedly the flux causes corrosion. I hardly ever clean my boards after soldering. I have boards that I soldered in the 70's that I never cleaned, and they still don't show signs of corrosion. Usually, the only time that I clean a board is if I am making it for someone else and I want it to look pretty.

WWNF911
05-19-2008, 12:11 PM
It really depends on the type of leaded solder you're using. If you are using a no clean type (you might see a code on it like NC601) then I ve been told you can use distilled water to clean the back of your board. This should be distilled by steam. Anything else may cause corrosion as Brian has mentioned. If you're not using no clean solder or even if you don't know which type you have, you should use the method Penfold and Tony have talked about.

moneyhunter
05-19-2008, 01:52 PM
Flux Off is manufactured by Chemtronics.

http://www.chemtronics.com/products/americas/e/flux_removers.asp

Appears to be rather safe and easy to use!

jeffathompson
05-20-2008, 11:05 PM
I have used a toothbrush and alcohol (Iso 91%) and gently brushed the joints. It seems to work well. after all that I take a blow dryer and dry off the board. Just remember to keep moving and not stay in one place as you can melt stuff if you are not too careful. Also, don't get to close with the blow dryer, about one and a half to two feet should do it.

These may not be the best practices, but they have worked for me.

I use the toothbrush and alcohol method too. Now I soldered my first board in March and here is my experience. I put 8 SSR's together. 4 home etched and 4 Oz boards. Half of them worked, the other half had little sizzle smoke sizzle flicker issues. It seems that flux can conduct enough electricity to fire the opto's and triacs. I took all the boards, scrubed the solder side with booze and a tooth brush, inspected all the solder joints, touched a couple up and the all worked perfect. The last 20 I put together I just take a couple drops of alcohol, scrub with the tooth brush, a couple more drops of alcohol and shake off into the trash can. Inspect and if needed touch and solder joints up. Out of 20 boards I had one channel that didn't come on the first time I hooked up the tester. That turned out to be a bad opto.

Oh, I do the cleaning BEFORE I put the opto' in the socket and I let them dry a good bit before testing them.

Now it may be my solder technique that needs cleaning, but in the mean time I have to clean my boards.