This might not be the right category for this, but it could fall into a couple of different categories.
I have been tasked to determine if any of these 3 solvents will corrode or damage electrical components in a sealed container.
- methyl ethyl ketone (MEK)
- Methyl Chloride
Most of my search has only resulted in what these chemicals do to humans and how toxic they are, nothing about their corrosion properties on electronic components and PCB when exposed. These 3 solvents dissipate quickly, but when we seal the container there is a concern that the chemical on the inside might cause issues later to the internal components.
Does anyone have any links or site suggestions on finding this information. Any documentation that is available would be a great start.
Try looking for PCB and IC cleaning instructions from a major chip maker like TI or Phillips. If you can find that, then their recommended cleaning solvents may suggest what not to use.
MEK and Acetone are strong solvents that will soften or dissolve so many polymers I don’t know where to start. I haven’t handled MCL before.
Corrosion probably not an issue.
Not to worried about the board itself because it should not touch the board, its just a matter whether the fumes that will be captured inside the enclosure would cause the electrical components to corrode or not.
All I can find is cleaning PCB with solvents. Some people had used MEK and Acetone, but not MCL (that I could find).
My thought is if I am cleaning a PCB with MEK or acetone the vapors are open to the environment and they will dissipate quickly as does the liquid, When it is enclosed, is the information I cannot find. I wonder if anyone has ever tested that.
What SparWeb said, but I wold add, Methylene Chloride is even more aggressive a solvent (and carcinogen) than the other two.
Agree, corrosion of metals is not an issue with the 3 listed, but softening of polymeric insulators, adhesives, binders, etc. would be a concern over a long period.
Is there any reason the container cannot be baked out to remove the volatiles prior to sealing?
The solvent is the sealing agent between the top and bottom ABS enclosure. Inside is a battery, PCB, and a sealed USB port heating it up is probably not an option.
I know MCL is a carcinogen… I don’t even like being around that stuff, but i have used it to test and it works very well on ABS, but its not worth the risk IMO.
If heat is out, could the box sit under vacuum for several hours or days?
Excuse my ignorance, but If its sealed what would the vacuum do for the fumes trapped inside?
The idea is to make this completely water proof. The USB port is IP7 waterproof so I don’t have to worry about water creeping in there and it has a rubber seal on it. Which will be tested when we get to that point.
The ABS box will be somewhat permeable to the solvents. Putting it in a vacuum will create a gradient, allowing some, hopefully most, of the residual solvent to dissipate through the box wall.
Thanks for the reply that is good information and good to know. I was not aware that would work. We are going to conduct some quick tests to see if anything happens. it really needs to be longer to determine if any thing bad happens inside but we don’t have a lot of time to determine that unfortunately.
Could you tell more about the electronics? Thinking in the context of ICs, some solvents could, not corrode, but erode a plastic case e.g. on a 7404 but a ceramic case, e.g. on a 5404 almost certainly not. It would be similar for a plastic vice metal case transistor. Of those three, acetone is likely the safest. Also should not be too difficult to fill the case with Nitrogen and seal it directly after, as done with some optics enclosures.
We are running some tests to see what happens.
I think we are serious looking an just doing some ultrasonic welding instead, if we can find away to keep the crystals from cracking, which as been an issue in hte past when we used ultrasonic welding.