Transcript
Phil
Welcome to board talk. This is Jim Hall and Phil Zarrow, the assembly brothers. Also by day ITM consulting. We talk about process and problem situations, equipment and materials. What is our question today, Jim?
Jim
Well, the subject today comes from M.M. and it's on water cleaning. Can water be harmful to electronic components? And M.M. says, we have been reworking circuit boards for the past 30 years.
After solder touch up, we remove the flux residues with ordinary alcohol, then clean with soap and water. Then dry each assembly with a blower. We have never encountered issues with microprocessors.
A new quality assurance engineer insists that electronic components, especially microprocessors should not be cleaned with water. Can you enlighten us?
Phil
Yeah, we can, where did this guy come from? Where the heck has this guy been? New, new to what? New to the industry? I'm speechless.
Jim
Water has been used as a standard cleaning, particularly for high rel products. The use of water soluble flux is cleaned with, in the best cases pure water, sometimes with saponifiers added, is a standard technique. Microprocessors, it's a standard electronic package. I don't see why there should be any concern.
Phil
We'll qualify this by dropping your cell phone in the dishwater in the sink is probably not a good idea. You know that in application in situ that's a bad way to clean your boards, but we've been using water cleaning for a long time.
Jim
The only explanation I can come up with. First, MM, you should have a little more confidence in yourself. You've been cleaning for 30 years with a very good process. Alcohol cleaning, followed by water, with soap or a saponifier in it's more generic sense, is the ideal way to clean a board. You've had good experience, so I think you are very right to question this new comer.
The only thing I can think of with microprocessors is thinking of them as a complex package, usually in a BGA configuration. And the concern about water not being able to get under, all the way under the part to flush out all of the residues.
In your case M.M., would be to flush the final rinse to get out the soap or saponifier in your final cleaning step, because, as we know, when you're using cleaning in chemistry such as soap or saponifiers, that leaving residues behind can be even more dangerous than the flux, because usually it has some of the flux chemicals dissolved in it.
So if we think about it, you get the alcohol, you've dissolved the flux, and you are washing the alcohol residues with the soap and water, but now you've got to make sure that you get all of that residue out of there. But I was wondering what this new fangled engineer was thinking of using as a cleaner and having to go back to some sort of solvent.
Phil
We know of one guy who tried to use Windex, but we won't go any further on that. The other question is where did this information come from anyway? I mean, one point is, have you guys had failures, have you had any drop in field reliability? If you've been doing this for a long time. So what prompted this?
Or did he read an article on the Internet? Another paper engineer. Go by your experience and your data. What is your data telling you?
Jim
The general statement that electronic components should not be cleaned with water is, I'm sorry, it's just ludicrous.
Phil
We look forward to your questions. Keep them coming. Again, this is the board talk guys, Phil and Jim saying, whatever you do don't solder like my brother.
Jim
And don't solder like my brother.
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