Anyone using Tetrachloroethylene to clean PCBs? - Page 1
Forum section: electronics / beginners

author: ablacon64
author_rank: Frequent Contributor
timestamp: June 16, 2013, 06:18:27 pm
content: Well, I'm researching some alternatives for PCB cleaning and heard about tetrachloroethylene as a flux solvent. It seems that it's very effective and was (is, I guess) largely used by the industry.So, anyone to share experiences? Is it safe? Does it damage plastics?Today I'm using methyl acetate but it's not very effective on tacky flux like Amtech 559.

author: mariush
author_rank: Super Contributor
timestamp: June 16, 2013, 06:30:52 pm
content: http://www.atsdr.cdc.gov/csem/csem.asp?csem=14&po=0Key ConceptsTetrachloroethylene is used mainly as a solvent for dry cleaning and metal degreasing.Like most chlorinated solvents, tetrachloroethylene can cause central nervous system depression.Chronic exposure to tetrachloroethylene may adversely affect the neurological system, liver, and kidneys.Tetrachloroethylene is reasonably anticipated to be a human carcinogen on the basis of limited evidence from studies in humans and sufficient evidence of carcinogenicity from studies in experimental animals.

author: sspj9
author_rank: Contributor
timestamp: June 16, 2013, 06:37:30 pm
content: I just use contact cleaner to clean the flux residue HA!... works fine...

author: G7PSK
author_rank: Super Contributor
timestamp: June 16, 2013, 08:50:21 pm
content: If you want to rot your kidneys just that little bit faster use trichloroethylene. Also puts you to sleep and was once used as an anesthetic.

author: ddavidebor
author_rank: Super Contributor
timestamp: June 16, 2013, 09:34:38 pm
content: What's wrong with the good old IPA dude?

author: ejeffrey
author_rank: Super Contributor
timestamp: June 16, 2013, 10:16:07 pm
content: Quote from: ddavidebor on June 16, 2013, 09:34:38 pmIPA doesn't clean (most types of) flux. This is a common misconception.

author: digsys
author_rank: Unknown
timestamp: June 16, 2013, 10:50:18 pm
content: I'm not sure what active ingredient is in FLU (Fluxclene), but it sure leaves PCBs SPARKLY clean !! WAY better than IPA, just a bit expensive.I was just about to ring up suppliers to find answers to your exact same question :-)Added: As far as "rotting your kidneys" .. all I can say is - bring it on !! We used to bathe in Carbon Tetrafluoride in the good ol' days :-)

author: ablacon64
author_rank: Frequent Contributor
timestamp: June 16, 2013, 11:58:01 pm
content: Well, sorry for not been very clear, I want to mix a solution for using in an ultrasonic cleaner.My goal is to make it fast and very clean, use an ultrasonic cleaner for 1 or 2 minutes only, using a good solvent. The problem is tacky flux, it becomes very gummy after soldering.digsys, I guess Flu is aerosol only, and very expensive in Brazil for large use.Quote from: ddavidebor on June 16, 2013, 09:34:38 pmIPA is not good on tacky flux, leaves too many residues, and the PCB aspect is not good, I want it to be like new (I did using IPA but it tooks several baths and the use of brushes).

author: Fsck
author_rank: Super Contributor
timestamp: June 17, 2013, 12:04:33 am
content: Fluxclene:http://www.electrolube.com/msds/044/044FLU-b.pdf30-60% cyclohexane10-30% isopropanol/propan-2-ol/isopropyl alcohol (10-30% 1-methoxy-2-propanol5-10% hexane isomers, with <=5% n-hexane1-5% heptane1-5% orange terpenes<1% hexane-norm

author: ablacon64
author_rank: Frequent Contributor
timestamp: June 17, 2013, 12:35:25 am
content: What liquid/solution are you guys using for ultrasonic pcb cleaning?Tomorrow I'll test 1 qt Water, 1 cup Vinegar, 1 Tbsp Salt and 1 Tbsp Dish Soap to clean some BGA stencils and see the results. I've seen this video (recipe above was taken from it) and the results on brass are pretty amazing:I'm searching for a cheap DIY solution for the PCBs also. I thought about using IPA and sodium bicarbonate powder. But I want to avoid unexpected results as solder cracks, specially on BGA chips.

author: digsys
author_rank: Unknown
timestamp: June 17, 2013, 01:08:08 am
content: After talking to my supplier, I'm no wiser. Just found this site -www.ipcoutlook.org/mart/50226D.shtmlHeaps of excellent info.So 40KHz or higher, Less than 10W/Litre, Less than 10mins, and preferably Sweep/dual Frequency (anti-cavitation).Now we got a start :-)

author: IanB
author_rank: Super Contributor
timestamp: June 17, 2013, 01:42:04 am
content: Quote from: ablacon64 on June 17, 2013, 12:35:25 amHmm. Wondering why on Earth that guy in the video was trying to use Simple Green to clean spent gun cartridges? Simple Green is a degreaser. It won't do anything with non-greasy deposits. For propellant residues you need an ionic solvent like hydrochloric acid. (Hint: a vinegar and salt solution makes a dilute hydrochloric acid solution.)For cleaning PCBs you need a solvent that does a bit of both. It would probably help to add some denatured alcohol to the water/vinegar/salt solution for this purpose.

author: uprightsquire
author_rank: Contributor
timestamp: June 17, 2013, 01:48:22 am
content: Quote from: IanB on June 17, 2013, 01:42:04 amThere is no real benefit to salt + vinegar over just vinegar. The chloride is irrelevant here.

author: IanB
author_rank: Super Contributor
timestamp: June 17, 2013, 02:02:28 am
content: Quote from: uprightsquire on June 17, 2013, 01:48:22 amOf that I am not entirely certain. I think the chloride ions may play a part. Chloride ions are known to have a catalytic effect and a corrosive action.

author: mazurov
author_rank: Frequent Contributor
timestamp: June 17, 2013, 02:20:49 am
content: Quote from: ablacon64 on June 17, 2013, 12:35:25 amFor boards being reworked (lots of half-burned rosin flux between fine-pitch pins) I use 60-70C 99%IPA, two 30 min.runs in ultrasonic bath, one to remove the bulk, another for final wash. Boards are cleaned witch compressed air after each run.For best results use glass containers, like standard chemical beakers, covered with lids made out of aluminum foil. Also, the water level in the bath needs to be tuned for the volume of liquid in the beaker by slowly adding water in running bath and observing results.

author: digsys
author_rank: Unknown
timestamp: June 17, 2013, 02:52:33 am
content: Quote from: mazurovJust for clarity : are you saying - fill the ultrasonic bath with water and heat. Place the PCBs into a glass "beaker" filled with ISO, cover and "float"in the water. (So we don't have direct heating of the ISO). If so, is there energy loss through the glass?

author: mazurov
author_rank: Frequent Contributor
timestamp: June 17, 2013, 03:16:21 am
content: http://www.tovatech.com/blog/3953/ultrasonic-cleaner/how-to-safely-use-ipa-in-an-ultrasonic-cleaner

author: mazurov
author_rank: Frequent Contributor
timestamp: June 17, 2013, 03:23:30 am
content: Glass absorbs some energy, yes. Everything else will absorb energy as well, the bath will self-heat. If your bath is explosion-proof you can pour IPA directly into it but then you will need to a) use more IPA, and b) clean the 5l bath as opposed to 500ml beaker. Also, for dirty boards you'll need two washes and consequently two ultrasonic baths. My bath takes 2 1L beakers, so when I wash a batch of boards, 2 washes occur simultaneously.

author: digsys
author_rank: Unknown
timestamp: June 17, 2013, 04:58:00 am
content: Great, thanks. Now all I have to do is find weird-ass shaped beakers / containers for the PCBs :-)I had priced 5L-25L bottles of various solvents and nearly popped an organ ! This should work out MUCH cheaper !!

author: mazurov
author_rank: Frequent Contributor
timestamp: June 17, 2013, 05:03:46 am
content: I use ordinary ones ->http://en.wikipedia.org/wiki/Beaker_(glassware)Work quite well

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2013, 06:36:31 am
content: I used an ultrasonic cleaner that used 100l of TCE at a time, and had a vapour reflow system to both dry he boards and distill the TCE to clean it. Found out that if you were more than 10s in the cleaner then parts would degrade, like rubber seals on capacitors. Leave a board in there for around a minute and the solder resist would be gone, along with most component markings. 5 minutes and the board would be bare GRP fibre again, all the epoxy gone, along with connectors and capacitor ends and bare film resistors. Drop a mechanical part like a carburettor in there ( cleaned off of most of the junk first, this was final clean) and 3 minutes later it was white. Same with waveguides and microwave parts, cleaned everything off including paint. Only plastic that survived was PTFE.If you want to clean flux best is a dirty bath with IPA and a brush to scrub, then a rinse and a final clean in an ultrasonic bath with a second rinse afterwards then a dry in a warm area. Do not rely on the ultrasonic to remove the whole lot, it is best for final cleaning, a brush and solvent is best to get mostly clean. As you go on the clean IPA is placed in the final bath and the solvents moved to a dirtier area, so you only have to discard a very dirty cleaning solvent, or filter it and use in the same bath as it evaporates. Filtering can be done with an electric fuel pump and an in line car petrol filter, it works well, you just put 2 filters in series with the pump in between them so it only gets relatively clean solvent to pump.

author: ablacon64
author_rank: Frequent Contributor
timestamp: June 19, 2013, 04:20:18 pm
content: Wouldn't salt help in the cavitation process?