In my experience IPA doesn't dissolve all flux residue, leaving an off white powdery material not due to IPA impurities. Acetone dissolves the lot, but can damage some plastics. I've been looking into Vapour Degreasing for the first time in many years and am surprised to find it is virtually a thing of the past. 3M sell some 'green' fluorinated solvents, but I'd imagine they're horrendously expensive. Flammable solvent degreasing would be just too dangerous indoors! Methylene Chloride is still readily available for some reason, but it's a potent paint stripper/plastic destroyer, so that's out for electronics. I was hoping at least there might be some small vapour degreasing tanks at scrap prices, but no sign of those either. I'd be concerned about using water based cleaning on very sensitive circuits, as described in a recent post. Although I wouldn't expect it to cause any problems with PTFE, it may affect the component package. A long bake after cleaning might be a good idea however you clean.. Alan ----- Original Message ----- From: "Robert Atkinson" <robert8rpi@yahoo.co.uk> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> Sent: Saturday, October 09, 2010 9:38 AM Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits Hi, Pure (99%+) IPA won't leave a residue. It my be dissolving dirt or a coating. For hermetic compounets a clean with dish washing soap and warm water in an ultrasonic cleaner, (followed by a second in fresh solution for very dirty parts), then de-ionised water and finally IPA is excellent. If the components can stand it (metal, glass, teflon, epoxy) pure acetone is one of the best finishing agents. Don't leave it to soak though. For non-ferrous metal parts add some ammonia solution to the first mix. Robert G8RPI. --- On Sat, 9/10/10, Randy Evans <randallgrayevans@yahoo.com> wrote: From: Randy Evans <randallgrayevans@yahoo.com> Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits To: jfor@quik.com, "Discussion of precise voltage measurement" <volt-nuts@febo.com> Date: Saturday, 9 October, 2010, 4:04 I will be using teflon stadoffs but I am using range resistors from an old Keithley 414 Picoammeter that were very dusty and dirty and I need to clean them prior to using them again. i did clean them with isopropyl alcohol but it left a residue on them that I want to clean off. Randy ----- Original Message ---- From: J. Forster <jfor@quik.com> To: Discussion of precise voltage measurement <volt-nuts@febo.com> Sent: Fri, October 8, 2010 6:23:36 PM Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits Picoamp stuff is usually done with Teflon standoffs or guarded PCBs, preferably the former. FWIW, -John =============== > Separate from cleaning flux off a board, what is the best solvent/cleaning > agent for removing dirt and grime from a board and compnents for the > lowest > leakage currents; e.g., for a picoamp measurement system with very high > value > reistors? > > Thanks, > > Randy Evans > > > > ----- Original Message ---- > From: Chuck Harris <cfharris@erols.com> > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > Sent: Mon, September 27, 2010 3:18:27 PM > Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits > > I don't like denatured alcohol. They add a little methyl > alcohol, which is very poisonous for skin contact, ingestion, > and breathing. Also, it is rather corrosive.... and worst of > all, it leaves behind a white powder when it dries. > > If you really want to use ethanol (the base for denatured alcohol), > buy it from the liquor store. > > Aerosol cans of "compressed air" are really filled with anything > but air. They used to be filled with freon, and then later butane, > NO2, and finally CO2. > > -Chuck Harris > > Andreas Jahn wrote: >> Hello all, >> >> thanks for the many informations and proposals. >> >>> From Your proposals I think the most interesting for my capabilites >>> are: >> >> - the isopropylene alcohol >> - and the "Kontakt LR" cleaner >> >> both for the last (3rd?) cleaning stage since the denatured alcohol is >> much cheaper. >> >> And I have learned that I should get some aerosol cans with compressed >> air for drying the cirquit. >> >> with best regards >> >> Andreas >> >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

In my experience IPA does dissolve all rosin flux residues. It is not as aggressive as Trichlor was. You have to provide a little mechanical help in the form of a brush. I use the tin handled glue/flux brushes for any scrubbing on the component side, and old tooth brushes for any scrubbing on the solder side. The boards I clean with fresh IPA are easily as clean as I used to get using trichlor in vapor degreasers. Also, IPA will not touch the citrus based fluxes that are intended to be water washed. I use solder with that awful flux for some customers that are particularly concerned about their hydrocarbon emissions. I have to use a flux hood, and a smoke straw then soldering. The water washed fluxes are strictly murder on your eyes and nose. Trichlor is so dangerous that it is no longer available in containers larger than about 1L. I don't think it is actually being manufactured any more, and any that you can buy (at high price) is left over stock from the 1970's. One 55 gallon barrel would fill a whole lot of pint bottles. Pentachlor is sold by CRC as a brake cleaner product. It smells just like trichlor, but is about 16lbs per gallon... very heavy! Any that hits the environment sinks immediately through the soil and down to the water table. And it is not a very aggressive cleaner. I am certain in a few years hence it too will be banned. It should be avoided. Water based cleaning is what the industry does these days. Virtually all parts are made to withstand short exposure to water and detergent. You might also notice that surface mount boards are not cleaned at all! They just leave the flux where it lay. I have fixed many irratic behaviors by scrubbing the boards with IPA and really removing the flux. It is slightly hygroscopic, and forms leakage paths. Regardless of how I clean, I bake the boards for a few hours at 50C in an environmental chamber (aka convection oven). -Chuck Harris Alan Scrimgeour wrote: > In my experience IPA doesn't dissolve all flux residue, leaving an off > white powdery material not due to IPA impurities. Acetone dissolves the > lot, but can damage some plastics. > I've been looking into Vapour Degreasing for the first time in many > years and am surprised to find it is virtually a thing of the past. 3M > sell some 'green' fluorinated solvents, but I'd imagine they're > horrendously expensive. Flammable solvent degreasing would be just too > dangerous indoors! Methylene Chloride is still readily available for > some reason, but it's a potent paint stripper/plastic destroyer, so > that's out for electronics. I was hoping at least there might be some > small vapour degreasing tanks at scrap prices, but no sign of those either. > I'd be concerned about using water based cleaning on very sensitive > circuits, as described in a recent post. Although I wouldn't expect it > to cause any problems with PTFE, it may affect the component package. > A long bake after cleaning might be a good idea however you clean.. > > Alan

Be careful about ultrasonic cleaners. They can break components internally. FWIW, -John ================= > Hi, > Pure (99%+) IPA won't leave a residue. It my be dissolving dirt or a > coating. For hermetic compounets a clean with dish washing soap and warm > water in an ultrasonic cleaner, (followed by a second in fresh solution > for very dirty parts), then de-ionised water and finally IPA is excellent. >   If the components can stand it (metal, glass, teflon, epoxy) pure > acetone is one of the best finishing agents. Don't leave it to soak > though. > For non-ferrous metal parts add some ammonia solution to the first mix. > > Robert G8RPI. > > --- On Sat, 9/10/10, Randy Evans <randallgrayevans@yahoo.com> wrote: > > From: Randy Evans <randallgrayevans@yahoo.com> > Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits > To: jfor@quik.com, "Discussion of precise voltage measurement" > <volt-nuts@febo.com> > Date: Saturday, 9 October, 2010, 4:04 > > I will be using teflon stadoffs but I am using range resistors from an old > Keithley 414 Picoammeter that were very dusty and dirty and I need to > clean them > prior to using them again.  i did clean them with isopropyl alcohol but it > left > a residue on them that I want to clean off. > > Randy > > > > ----- Original Message ---- > From: J. Forster <jfor@quik.com> > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > Sent: Fri, October 8, 2010 6:23:36 PM > Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits > > Picoamp stuff is usually done with Teflon standoffs or guarded PCBs, > preferably the former. > > FWIW, > > -John > > =============== > > >> Separate from cleaning flux off a board, what is the best >> solvent/cleaning >> agent for removing dirt and grime from a board and compnents for the >> lowest >> leakage currents; e.g., for a picoamp measurement system with very high >> value >> reistors? >> >> Thanks, >> >> Randy Evans >> >> >> >> ----- Original Message ---- >> From: Chuck Harris <cfharris@erols.com> >> To: Discussion of precise voltage measurement <volt-nuts@febo.com> >> Sent: Mon, September 27, 2010 3:18:27 PM >> Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits >> >> I don't like denatured alcohol.  They add a little methyl >> alcohol, which is very poisonous for skin contact, ingestion, >> and breathing.  Also, it is rather corrosive.... and worst of >> all, it leaves behind a white powder when it dries. >> >> If you really want to use ethanol (the base for denatured alcohol), >> buy it from the liquor store. >> >> Aerosol cans of "compressed air" are really filled with anything >> but air.  They used to be filled with freon, and then later butane, >> NO2, and finally CO2. >> >> -Chuck Harris >> >> Andreas Jahn wrote: >>> Hello all, >>> >>> thanks for the many informations and proposals. >>> >>>> From Your proposals I think the most interesting for my capabilites >>>> are: >>> >>> - the isopropylene alcohol >>> - and the "Kontakt LR" cleaner >>> >>> both for the last (3rd?) cleaning stage since the denatured alcohol is >>> much cheaper. >>> >>> And I have learned that I should get some aerosol cans with compressed >>> air for drying the cirquit. >>> >>> with best regards >>> >>> Andreas >>> >>> >>> >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > >       > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >