Question for you guys…
What is your process for removing excess flux from your boards and cleaning them up? I read some people on other sites put their entire boards in water as the final step in their process? Really?
I’m having some shorts in my Barton User Quantizer and am wondering if it’s the excess flux around some of the joints? The board is so tiny that I’m thinking there are maybe some flux “bridges” in places? Flux is conductive, yes?
Flux is not conductive, because it consists mainly of rosin. I learned from the youtube video below what fluid flux is. It is rosin dissolved in alcohol, so alcohol could be able to wash it away.
Interesting. Okay, my flux “bridge” theory is out the window…haha. Thanks…
Maybe if rosin burns, it gets conductive if carbon is created as a side effect. But I’m no chemist …
Depends on the flux, but it’s usually somewhat conductive, but not in a way that matters unless you do very specialized stuff.
Isopropyl alcohol (99%) usually works. I have some random “flux remover” thing that iirc contains isopropyl alcohol and some other solvents and works ok.
I have never bothered so far, but I was told that a good method is to soak a paper towel with alcohol, put it on to your pcb and then rub it with an old toothbrush… this way you don’t get the alcohol (and flux) everywhere on your desk. 
You can use IPA alcohol or unnatural if you want go cheap. Anything with 80%+ alcohol will go. Do not use vodka, contains to much water : )
Yes, using old tooth-brush is protip. In factories they use IPA dispenser with small brushes -at least where I worked : )
Of course if you don’t have alcohol already, good luck finding it.
This came up in my RSS feed this morning:
though it may not be very helpful especially outside Germany.
I use 90% alcohol and a cheap vibrating tooth brush. If you use just a tooth brush use the strongest bristle you can get(Don’t brush crazy hard). Brush with the alcohol and wipe the brush on a rag(white too see rosin come off) so the rosin goes off the pcb onto the rag. Have too do a few passes so you get most of it so it doesn’t spread and make the PCB sticky.
It is less of a issue now because I got some new solder that has less rosin and make less of a mess.
Must rosin flux is non-conductive and is safe to leave on the PCB. Water soluble flux IS CONDUCTIVE and it absorbs water and is mildly corrosive; it should be removed. Really hot water and a little bit of dish detergent will work in a pinch. Bake at 70-80C until everything is dry. Rosin flux is removed with isopropyl 99% alcohol. Try not to get it on your hands. The high concentration alcohol in incredibly hygoscopic and will suck all the moisture out of your skin. Fingernail polish remover and brake cleaner can possibly damage components and the PCB so use at your own risk I guess. You all are building some circuits where leakage currents will affect the circuit performance and keeping things clean helps.
I guess the discussion about flux stems from using flux as an additive to (de)solder SMD-components. Not so many people do that, but for those who do if I sum up the above discussion up correctly then water based flux seems to be the only flux that may influence the circuits people are building here given that it is conductive as you say. That would then be caused by the water in the flux combined with some salt like component? Would that not evaporate after a while (within a few minutes after soldering) and loose its detrimental effect?
The rosin core that is in my solder has not produced any problems to me in many years of using it.
This is for cored solder, not pens or additives. Rosin is fine to leave on the board. It can attract dirt but oh, well. Water soluble flux remains conductive even after they are “dry”. I had to do some research on this when our first article radio PCBAs didn’t work. High impedance nodes were measuring at like 200k. Washing and drying made all of them work. This experience was repeated at another place where a technician used it to rework a board. There was excessive leakage current which was fixed by washing. You don’t have to submerse it. Using water like you would use alcohol is OK. Using an alcohol wash after a water wash helps remove the water too.
So I’m not sure what it did, but I put some alcohol on the board and scrubbed it with a toothbrush and the shorts in the box header are all gone. 
I’d like to clean up my Yarns SMD DIY board that I put together, but wanted to be sure first that I could do that considering the stm32 chip and a few other chips. I don’t want to ruin anything on the board. Is there anything on here that would prevent me from using alcohol and a toothbrush to clean it up?
Here’s a link to the BOM.
That should be perfectly safe to do.
Isn’t anyone in this thread going to complain about “PCB boards”? 
I mean, I would, but I’m busy trying to remember my PIN number for the ATM machine.
You mean that the “B” in “PCB” actually stands for Boards and saying “PCB Boards” is redundant?
RAS Syndrome is funny.
other funny ones include:
PDF Format
LCD Display
UPC Code
CNN News
FBI Investigation
Please RSVP - Please respond s’il vous plait (French for “please”)
RAS Syndrome is itself a phrase that exhibits this behavior.
I just scored another almost full can of Brake Cleaner after a neighbor had a garage clean out.
Bought new it’s still way cheaper than other cleaners and comes in a handy lifetime sized tin.
Great for wiping down stripboard pre and post solder and eats flux, grime, rust and quite a lot of other oxides.
You could even use it in a ultrasonic bath if you want to get a board squeaky clean.
Dries fast and no scum or residue.
Enjoy
Ooooh! Thanks for this! There was a tin of some sort of brake thingy when I first moved into my current shared workshop. I can’t remember if I threw it out or not, but it’s a 15 minute bus ride away so I can’t exactly nip out and check 
I’ll look on Sunday. Thanks again 
I use 96° isopropyl alcohol and a toothbrush which works well on stripboards. On PCBs, however, I get a dull/sticky looking result on the surface. Has anyone else experienced anything like this?
