Removing the flux from a PCB.

[mickm3for]

Hi any ideas as to the removal of rosin flux from an esd sensitive smd pcb
I can solder the .5mm space chips ok (mcu chip) but it looks horid because of the flux i have used esd brush and lots of ipa. Has any one an alternitive to kimwipes as they dont seem to be available in UK. Would boots lens wipes be ok they contain Aqua, Alcohol Denat thanks for any advise Mick

[Terry_VK5TM]

My normal method is similar to yours - old toothbrush and IPA.

If the board looks smeary afterwards, then a wipe with a damp tissue.

For future reference, find yourself a water based flux , so much easier to clean up (used with Rosin core solder it helps dilute the solder flux -works perfectly well in combination).

[Diabolical Artificer]

I tend to use any solvent to hand, meths, IPA, nail varnish remover or whatever and an old toothbrush like yourselves but sometimes use pre injection wipes, I use these for cleaning heads too. These are available online.

I did try and buy proper flux and remover but bailed out when the postage came to more than the product. Maybe the legislator's are worried that anything with chemical's in will turn homicidal and leap out the bottle brandishing a Kalashnikov, that or blow itself up; beware of fundamentalist battery's.

Andy.

[G4YVM David]

I dont know about flux but I am so pleased to see the word "kimwipes". Ive used this word for decades and my wife always asked me why I call hem that..i haven't a clue and have never been able to give her an answer. Id started to think i'd dreamt it or misheard the word "chemwipes"... Now I know I'm not alone!

Thanks for that little bit of boosting. Kimwipes it is!

[evingar]

Kimberley Clark scientific wipes - knee deep in them at the "day job"

Kerosene for motor planes is the best, no residues, no water and disappears inmediately, if not, the zippo lighter gasoline is the best in my opinion. After clean with AIP

[Radio Wrangler]

Kimwipes were the standard-issue things at HP in the UK. They got used for almost everything. Too rough and scratchy when you had a cold, though. There was a box on just about every bench, next to an aerosol can of Inhibisol solvent (Trike!). They were standard things in the US so they had HP part numbers, so they were what stores stocked.

Nowadays, I use a stiff brush - a straight one because toothbrushes put your knuckles into the cut stubs of component leads, and iso-propanol. There are good flux removers from RS and Farnell. Or else after iso-propanol I use fairy liquid and tap water with distilled water for the final rinse.

Acetone/nail varnish remover/cellulose thinners is a bit too good at dissolving plastics.

David

[Lloyd 1985]

We use something called ‘Ultrasolve’ at work for flux removal and general PCB cleaning, works very well, leaves the PCB looking nice and clean when IPA sometimes leaves them looking a bit like there is some white residue on them. It also seems to shift burnt flux much quicker than IPA. I use an ESD safe brush, and then mop up the dregs with an ESD safe wipe.

Regards
Lloyd

[Sinewave]

I use Electrolube Flux Remover. It's a spray thought a stiff brush.

[G4YVM David]

Thanks. I must have been Kimwipes when I worked at CMB Wantage in the 90s. Sorry to hijack the thread

[John Caswell]

Isopropanol (IPA), stiffish brushes, Kimwipes or CPC large blue b*g roll plus compressed air of some sort to clear component side.
Used to have the benefit of a proper heated PCB cleaner, sheer bliss!

John

[cmjones01]

I use either Ultrasolve, as Lloyd says, for professional work, or for home and prototype stuff I use car brake cleaner. It comes in large, relatively cheap cans and does a great job of dissolving flux residue and other sticky stuff.

Chris

[MotorBikeLes]

I have a thick darning needle (maybe not a darner, it has a good point) pressed and araldited into a wooden handle. When I used to do CD player repairs, with many "postage stamp" sized ICs with 50 to 100 legs, I used to rake it between each gap between legs. Not only did it remove the (brittle) flux, but would immediately highlight any leg which looked soldered but was not.
After the raking out, cotton wool buds (Johnsons usually the best) soaked in IPA to leave a clean board.
I use that same tool for all flux removal, but it really waas essention with the multi leg ICs.
Les.

[kalee20]

I use Electrolube Fluxclene, it works really well! IPA tends to soften flux and spread it around, but Fluxclene completely dissolves it.

If I want a completely smear-free board I use Fluxclene, wetting it and letting it soak for a few minutes, then brush it off with a toothbrush dipped in Fluxclene. Finally I swill it with IPA (which is cheaper than Fluxclene) and blow it dry with an air line.

Acetone or methyl-ethyl ketone (acetone is dimethyl ketone so is slightly more volatile) works very well, but is more aggressive. It can start to remove markings from components, colour codes from resistors, etc, so I avoid it.

[electroanorak]

Cellulose thinners, but not near polystyrene caps...

[Diabolical Artificer]

Nobody's mentioned conformal coating and he effect some chemicals have on it. Most PCB's I muck about with don't have it but I've has a few where IPA has turned the board into a sticky mess.

Andy.

[dsergeant]

I use Servisol Deflux 160, available from CPC and elsewhere, together with a stiff pcb cleaning brush that I probably got from them years ago. But not used it much for surface mount work.

Dave

[Vincent]

Surgical Spirit from Boots and cotton wool/pads. Works every time all the time. And generally very handy on cleaning/degreasing during electronic works.

https://www.boots.com/boots-surgical...500ml-10075125

[Sinewave]

Originally Posted by Diabolical Artificer

Nobody's mentioned conformal coating and he effect some chemicals have on it. Most PCB's I muck about with don't have it but I've has a few where IPA has turned the board into a sticky mess.

Andy.

Any boards with conformal coating I've encountered was for a repair where replacement components were so few that I found it acceptable to not need to clean the flux. That and the type of flux cored solder I used on coated boards.