[Idea] Vapor Phase Cleaner Design - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: January 21, 2018, 04:39:53 am
content: We all know the pain of cleaning tacky flux from PCBs, and vapor phase PCB cleaners come to the rescue -- except that they don't come cheap.I was thinking if I can make one from easily obtainable materials and form a closed system that can be placed on my desk.This is a draft of my design. Peltier element (5) heats the beaker containing acetone, and the hot side of Peltier is roughly held at BP of acetone.Vapor travels through beaker to the top, where the majority gets condensed by parabolic condenser (2), which is cooled with water.Escaped vapor gets confined in cover (4), travels down to Peltier cooled cold plate (6) and gets condensed.To further decrease cold plate temperature, thermally insulating material (7) is used to prevent heat transfer from bench top to cold plate (6).Out of the system, a pump circulates water between heat exchanger (1) and a radiator to keep condenser (2) cool.Overall, Peltier element (5) introduces heat into the system, and heat exchanger (1) removes heat from the system.A silicone dam surrounding the Peltier element (5) and its cables prevents acetone corrosion.This system, if will work, can be made cheaply with Hobby grade materials.Peltier element (5) can be purchased form Mouser, CUI makes them.Beaker (3) can be a normal tall beaker from any chemical supply store.Parabolic condenser (2) is the only part that needs to be machined, but it can be made of easily machinable materials like 6061.Heat exchanger (1), pump and radiator can be purchased as a kit from any computer watercool system store.Dripping pan (6) can be any thermally conductive metal pan, a meat loaf pan glued on top of an aluminum sheet is more than enough.Cover (4) can be an inverted glass jar or 5 glass panels glued together with RTV (or anything resisting acetone).Thermally insulating material (7) can be a block of wood or better, refraction brick, or just dried soldering sponge.Including an AIO CPU cooler, the entire system can be made for less than $100 (excluding power supply).Any ideas if this will work?//Edit: typo.

author: duak
author_rank: Super Contributor
timestamp: January 21, 2018, 06:11:02 am
content: Please read up on acetone and how combustible it is. I believe most PCB cleaning is done these days with fluorocarbons which are pretty much inert but don't work as well as some older solvents. Years ago we used trichloroethane that could remove flux and many inks and plastics - but at least it didn't burn.Anyway, I wanted to clean some grungy mechanical parts but standard solvent wasn't doing the job. I had a steel bucket with a tight fitting lid that was used for printer's ink about the right size. I put the parts in and added about 500 ml of solvent then heated an area on the bottom with an electric element to about 80 C. An hour or so later the parts were clean and all the oil, grease and grime were on the bottom of the bucket. BTW, I did this outside just in case.I think a peltier is overkill for the task at hand and is perhaps dangerous because if it fails it could be an ignition source inside the overall container.Best o' luck,

author: ezalys
author_rank: Frequent Contributor
timestamp: January 21, 2018, 04:54:10 pm
content: Oh yeah with acetone this is a bomb. Even in cleanrooms we have special hot plates for heating solvents with tons of extra shielding and safety precautions.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 21, 2018, 08:45:45 pm
content: I worked for a small company making LCD displays.This is going back to early eighties when such things were done in Australia.Two people in total working in the company other fellow was a brit a specialist in glassware for the displays.Used a vapor phase cleaner to clean the glass.One morning i came in as usual only to find a buch or rubble and ash where the workshop used to be.Aparently the boss had forgotten to turn thecleaner off.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 22, 2018, 12:29:53 am
content: Years ago I worked with one. We used 1,1,1 trichloroethane because it's supposedly not as toxic as trichloroethylene. A poorly deigned ventilation system pulled the cold layer off the top, and most of the solvent eventually went up the vent. The unit then caught fire when the mixture of oils and solvent in the bottom overheated. The bad thing is if you burn trichloroethylene you get phosgene- nerve gas. The use of both those solvents is no longer allowed, and nPB is probably on its way out. Look at newer alternatives like 3M Novec. Acetone? No way.Building a machine is easy. Heater in the bottom and cold water coils around the top. Ideally the bottom boiler is divided into two sections so distilled solvent accumulates in one section, and overflows to the boiler section. People have made them in the lab with nothing more than a beaker and some cooling coils around the top. IMO, it's not worth messing with in this day and age. Acceptable solvents are probably expensive and have to be reclaimed as hazardous waste. You don't want any drafts around the system because they disturb the layer of cold solvent. That makes a fume hood problematic- the very reason we had a fire at the old place. It takes a certain knack to use them properly. Overexposure to the solvent is likely. I don't think a TEC is at all the best way to do this. All that said, there's nothing quite as clean and grease free as a properly hot vapor degreased part.

author: helius
author_rank: Super Contributor
timestamp: January 22, 2018, 01:27:47 am
content: The glass beaker version is called a Vaporette. They were made at one point by Multicore for vapor phase soldering, and have a condenser sleeve molded into the glass. Unfortunately they are hard to search for since the word has become fashionable to use for a completely different type of product.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 22, 2018, 02:39:58 am
content: Ultrasonic cleaners could be bad juju as far as the micro wires inside some IC packages are concerned. Vibration may cause a fatigue failure of the joint.