I have a few basic questions about cleaning up a PCB after soldering, especially after SMT soldering with pre-fluxing.
What are the best ways to clean the board? I’m using a basic rosin core lead solder and a rosin flux pen.
Any resources out there that describe and explain the various PCB cleaning methods?
Secondly, if I have a part which cannot get wet by dishwashing the PCB, what’s the best alternative for cleaning the board without water?
Brush with iso-propyl alcohol.
Leon
Thanks, Leon. Any particular type of brush work the best? Stiffness? Would a toothbrush work?
I use an old toothbrush. You need 99% IPA, BTW.
Leon
Thanks, Leon. That’s what I needed to know.
I have a flux cleaning spray which I use with a toothbrush. I’m guessing it’s mostly alcohol.
I use a an utlrasonic cleaning tank with a product called Safewash. http://uk.farnell.com/electrolube/swas0 … /dp/725687
I put the boards in the ultrasonic tank for about 2-3 mins, wash off in fresh tap water to get all the cleaning fluid off. I then rinse off in deionised (distilled) water and then dry in an oven. (My Reflow “toaster” oven has a drying cycle)
The boards come lovely and clean with nice shiny solder connections. Its good for getting rid of any little solder balls left hanging around (if your using solder paste).
The only caveat I would add is check what compents you have on your board before doing this. Most stuff is ok like chips, passives, connectors etc. The sort of parts to check the datasheet on first is stuff like electolytic caps in can’s and certain LED’s.
I destroyed most of the SMT LED’s on one of my boards becasue I had not appreciated that the encapsulating material was clear silicone instead of the usuall clear expoxy. This meant when they went into the utrasonic tank the tiny gold wires inside LED’s became fracture or detached from the semiconductor die. The silicone does not protect them half as good as the epoxy encapsulated verions. However the new silicone devices are reputed have better life perfoprmance.
Thanks nurquhar. Out of curiosity, what kind of disposal is required for the Safewash? Any particular ultrasonic tank you recommend (what size are you using)?
Trying to get a handle on the benefits of this method - seems like the main one would be you can do multiple boards at the same time and not have to hand clean each.
Not to sure about disposal as I havn’t ever throw it away. The last batch I had that got a bit “merky” I just strained it through some perky coffee paper filters. Came out nice and clear again.
I looked at the safety datasheet. http://www.farnell.com/datasheets/355364.pdf It does’nt look like something realy nasty like the bleach you clean your bog with, I guess this is why they call it “safewash”. It just realy warns about it may be an irritant. It does mention disposal, the answer to which is likley as not to mean there is no definative answer, ie “Dispose of waste and residues in accordance with local authority requirements”. I would look at this way, where are you told to dispose of your household bleach when you read the label on the back of the bottle ? Or that really useful safety datasheets the checkout girl gives you with every purchase ? Not!. Its like lot of burocracy in life, your told you must do the right thing! But what is the “right” thing, you ask ? You must seek your own independant advices, we can’t advise on that.
As for tanks I started with small tank I got of eaby for about £50. Like this one http://cgi.ebay.co.uk/ws/eBayISAPI.dll? … EF:GB:1123
It was supposed to be for cleaning jewelery or tattoo needles. It worked fine. I moved to a bigger tank for about £120 like this when I needed to do some bigger circuits. http://cgi.ebay.co.uk/ws/eBayISAPI.dll? … EF:GB:1123
However the one I got was a cheaper model of the same size. It still had heater.
Thanks for the extra info, nurquhar, I appreciate it.