I use reagent quality Propan-2-ol. About as pure isopropyl alcohol as you can get. Not the cheapest, but cheaper than lab ethanol.
Any lab supply house should have it.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Check and double check! Getting "crud" out from under components is a rather nasty problem. It is a wonder that someone has not developed and marketed a thin material not unlike a sheet of polypropylene to put on the PCB before the parts go on. Then an appropriate solvent would have a chance of removing that sheet - leaving a gap to allow final cleaning.
That seems like a bit of tricky engineering and balancing of trade-offs; could result in a "killer" patent and product.
Color me ignorant..what would the hydrogen do?
It reduces the metal oxides the way flux would, so that you can make good solder joints with no flux and no gold. Forming gas is generally
2% H2 in N2, which has much the same effect with zero explosion danger. (There's no ratio of forming gas with air that makes an explosive mixture.)Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Lab grade 95% ethanol is cool. And you can drink it !
Greg
It doesn't get any more retarded than you are.
I think the idea is to manage the temperature gradient in the vapour so that it's supersaturated when it gets to the parts being cleaned.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
There is a reason why you never see 100% and there is a reason why the remainder IS ALWAYS water.
Note the smiley. He was joking. Hydrogen is EXTREMELY flammable.
Reflow processes do have Nitrogen flooded reflow zones though. It is very expensive and few contract manufacturers include the option when they buy their hardware. Likely not a part of the RoHS schema, but man oh man did it ever make nice solder joints in the leaded days.
alcohol
Hydrogen isn't a joke, it's used for exactly this in some places. For instance, IBM East Fishkill is the largest user of hydrogen gas after NASA. They have a 30-foot-long hydrogen-filled belt oven that's used for curing glass-ceramic substrates. That whole end of the building is covered with blast doors, and inside it looks like the throne room of the Great Oz.
Back in the day I helped a friend try to build a particle counter for contamination monitoring inside that oven. It turned out to be too hard, due to thermal lensing.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
here.
alcohol
The less adventurous assemblers use nitrogen in their reflow lines. A good line will go through a 6-foot dewar per day.
-- John Larkin, President Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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Forming gas is good medicine for lots of things, though.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...
It becomes a problem if the device does not allow washing between it and the PCB. Like relays and switches and those pesky Piezo buzzers.
Cheers
What i saw was a continuous flow of liquid on the PCB flowing more-or-less evenly down (PCB was held more or less vertically). There may be a reasonable chance that the vapor would penetrate under a BGA, but i think there would be less penetration on a same-size flat package (i call them "squashed bugs") due to less clearance. Experimentation will tell how "good" that might (or might not) be. Take the largest "squashed bug" and a BGA of same/similar as possible size and reflow them on a PCB with lycopodium or other "tracer" material (fake but observable dirt) placed on the PCB before reflow. You proly will have to select different particle sizes to determine the effective transport factor (or whatever the term is, in this case). Make a graph, publish it and present it as your Thesis..
Cool! Do most assembly houses "purge" their reflow ovens that way?
Probably correct especially for the Industrial units. For my crude degreaser, i dunked the board all the way into the (invisible) vapor; guaranteed supersaturation.
Yes, but it isn't cheap and not worth the price to use it in electronic cleaning processes.
For a hobbyist maybe. Pretty dumb to even suggest it.
IPA is NOT ethanol.
He should have used IR sensors then.
The nice thing about scuba air is it doesn't spray out refrigerant like the canned air does if you don't hold the can level. I haven't bothered to research industrial gasses. I figure if the scuba air got to be a pain, I'd get a compressor and filter.
I think the scuba air is more powerful than canned air. I can spin fans around when I blow out PCs.
You have a good idea there, but I think what you would want is something pre-attached to the parts themselves. That way you could be sure the contacts of the SMD were touching the board. That is, make the part so that with the pad attached underneath it, the metal contact would still extend beyond the part in the Z axis.
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