I was working on a batch of
ReproPak boards today, and after finishing I attempted to clean the rosin spatter with 99% isopropyl alcohol. I noticed this caused the solder mask to become sticky, and after drying none of the boards functioned at all (would not boot).
I have built many ReproPak cartridges in the past, and I remember this happening once before but I wasn't sure if it was related to using alcohol on the PCB. Since then I avoided doing that just in case (i.e. cleaning the card edge contacts only, but leaving any rosin on the board), but something compelled me to try it again today, and given that all of them failed without exception it does seem to me that the alcohol did some serious damage to the boards.
Has anyone else experienced this? I've cleaned lots of other PCBs with isopropyl alcohol and they never became sticky as a result, just these ReproPak boards.
Edit: I have found a solution to this problem. With a very thorough scrubbing with more alcohol, followed by a quick rinse in water and a quick dry, whatever the offending substance is eventually washes away.
Not sure what it was. Rosin would explain the stickiness, but I don't know why it could cause the board not to function. It appeared to me that when I began scrubbing the board would become sticky on its own, whether or not there was rosin spatter. With further scrubbing it would eventually go away.
Please name PCB manufacturer(website or whatever...).
That's not disclosed anywhere on the board (just says "sealie computing" on the silkscreen, but that's retrousb obviously).
Doesn't the manual warn you not to use it ANYWHERE except the cartridge contacts? I seem to remember a warning in the manual.
No, but I think it should.
http://www.retrousb.com/downloads/repropakmanual.pdfQuote:
3) ReproPak contacts can be cleaned with rubbing alcohol and cotton balls. Be careful cleaning the case as
some solvents or rubbing alcohol can destroy it.
If "case" means "PCB" then that's been an expensive typo on my end. I presumed this was a reference to the plastic cases.
The isopropyl alcohol leaves a sticky surface behind, but there is otherwise no visual evidence of damage to the board after using it. I dunno, I've been cleaning grime/rosin/dust off PCBs for years with alcohol with no problem. Is this problem common with custom made PCBs in general, or is it just something specific to this one?
It's conceivable that the alcohol has moved some of the resist off where it should be (protecting the traces where it's red) and onto the places it shouldn't be, and so blocking electrical contact.
Does a continuity meter tell you anything useful?
I used it only after all soldering was complete, so I'm not sure how it would block any needed contact at that point, and I am not sure if solder would migrate to newly exposed areas either. It's kind of mysterious. Everything is still visibly red where it should be, just a bit sticky.
I tried desoldering and resoldering one of them, but it didn't seem to help. My multimeter doesn't have a continuity mode, but I did do some checks with the ohmmeter. I didn't get any helpful information out of that.
Might you post of picture of it? Or is there really nothing to see?
If you're going to write it off as a loss anyway, I'd be willing to take a look and see if I can fix it.
Hm, I could take a picture of the bad boards, but they look the same as a good board in a photograph.
Hmm, now that they've been drying for a day they're not really sticky anymore. I guess whatever substance was created by the interaction takes a while to dry, unlike the alcohol itself.
The end result is that the solder mask surface is rough to the touch instead of smooth, to varying degrees (I guess depends on how hard I brushed it at the time). Still the same behaviour now that they're dry though: game won't run.
If you'd like a pile of non-functioning boards I'd be willing to mail them to you. I just consider them a loss; I've tried as much as I'm willing to get them working. I had actually thrown them in the electronic waste bin, but they were still there today so I took them back out to look at them.
If isopropyl alcohol is going to destroy the PCB from contact, that's not okay as far as the PCB design goes. I've doused (turned-off and discharged) NES and SNES motherboards in alcohol as well as liberally applied it to cartridge PCBs that were properly manufactured with no such issues... it should evaporate on its own and be as if it was never there.
This is such a weird thing, it doesn't make any sense to me... Before considering them a loss, try contacting bunnyboy on Irc. He seem usualy pretty busy but if I was manufacturing PCB to sell to hobbyist like he is, it's something I would be damn interested in hearing! If this is the case, I wpuld write a big notice in cap on the product page and in the manual. I hardly think you are alone cleaning pcb with rubbing alcohol, I do it all the time and I'm certain many other do the same as it's one of those thing that evaporate so fast. You're saying the boards we're assembled and tested before the cleaning took place? If they stopped working right after, and won'r work after they dried up for days I think it would be worth it to investigate as I do not see any logic behind it. If for sone reason the coating react with the isopropyl alcool, how could it even create such trouble? I understand your confusion as I'm at a loss here too.
I'm curious as to why the top of the board being a little weird would ruin the copper underneath.
My guess is the clear coat or whatever the boards are finished with dissolves in the alcohol, and dries in a day or two. Still doesnt really make sense that it would prevent the boards from working though. Bunnyboy has recommended "Myro" for PCBs in the past, not sure if that's who he uses or not but it might help the investigation.
For some reason I think I've had similar issues with some PCBs I've ordered elsewhere. At the time I thought it was due to the flux not dissolving well in alcohol. They worked fine though so I never thought much of it.
The only thing that should be conductive on those boards is the copper... It's possible the sticky mix is conductive, but if it's not enough to pick up with your ohmmeter on the highest setting then I doubt it's the problem. I would try replacing all the roms and chips on the board, vice just resoldering possible bad roms.
So just now I decided to pull one of my old repropaks out and see if I can find the same problem. I applied a LOT of alcohol several times and never saw any such stickiness. Are you sure your applying enough alcohol to fully dissolve and remove the solder flux? Do you have some weird solder with bad flux? You could always try an alcohol bath and see if it improves or worsens since you're considering them trash.
Honestly, I don't have an explanation for it. I'm just describing what I've seen. If I use 99% isopropyl alcohol on my repropak, it becomes sticky and no longer functions. That's all I know. I'm pretty content to just move on and not put alcohol on others in the future. I'd rather not spend 20 hours getting to the bottom of this when I could spend that time making working boards with fresh parts.
As for continuity testing, I wouldn't say I've done a thorough test. The ohmmeter doesn't update quickly anything, and there's like 150 points of contact to test, so it's not like I can try every possible combination. As for whether my flux is weird... this has happened with two different rosin-core solders from different manufacturers. I kinda doubt there's anything special about the flux, but... who knows.
Specifically what I did was dip a toothbrush in alcohol, then scrubbed the back of the board with it. After that I waved it dry and left it under a fan for a bit.
I was really just wondering if anyone else has had this problem. It doesn't really make much sense to me that this would damage a PCB. Sounds like it hasn't happened to anyone else, though? Maybe this only happens to me and something else is going on.
I could take one of my working boards and start giving it the alcohol treatment progressively to see when it fails, but I don't think I would find out anything interesting and I'd rather just have one more working board.
99%.... That might have something to do with it. 50/50 is probably more appropriate. That's what I'm issued to seeing used anyways and haven't seen issues.
I clean my pcb with 99% and never had such issue.
I do as well. It's only the repropak which is giving me a problem with it.
Hmm, now this is very interesting. I took a few of the non-functioning boards and gave them a thorough rescrubbing with the alcohol. The stickiness seems to have scrubbed away, and the boards have come back to life (has worked on 4 boards so far).
So, that's good news. I'm glad you guys asked enough questions to get my interested enough to try this... hopefully I can recover the others too.
Sounds like I won't need to investigate them!
I'm glad to hear that! I hate when things goes to waste.
Wow, all 12 boards came back to life. This is great.
So... my solution was just to give them a really heavy toothbrush scrubbing front and back with the same alcohol, then a brief rinse with water, a quick pat with a cloth and a dry in front of a fan.
All of them work now after doing this. Very strange.
A lot of sticky residue came off on my fingers while doing this. A lot of the boards felt sticky after I started scrubbing, but eventually they all seemed to come clean. Very odd; I don't know -what- exactly I'm washing off (it doesn't seem to me that rosin should be the cause... but I dunno), but I'm glad this worked.
Are you using some new solder or something that you're not used to? I think my similar experiences were when I've used some cheaper solder. I'd put my money on the rosin/flux, but who knows. Good news is you were able to bring em back to life!
Bad batch or either "ecofriendly" soldering mask, which not supposed to be cleaned AT ALL.
I dunno, I had this problem on two occasions and in between I switched solder, so I would tend to discount that. My current solder is 0.8mm "super solder wire: the best quality solder" 60% stuff they sold at the local electronics shop. The previous solder was Nexxtech "rosin core solder for PC work", also 60% but 1.2mm diameter. If I leave the board with rosin spatter on it, it doesn't look so nice, but the board works fine.
Light scrubbing with 99% isopropyl alcohol messes up the board for me. Heavy prolonged scrubbing cleans it back up. The stickiness seems to come after light use of alcohol, even if I do it on a clean looking corner of the board, so I'm not really sure the rosin is even a factor here. Anyhow, more alcohol and more scrubbing take it away again so everything is fine now.
I was actually only trying more alcohol because I wanted to verify that this was happening; so I was actually scrubbing a board really hard, trying to just see if I could wear away the solder mask entirely, and that's when I noticed the stickiness went away after a bit. Maybe there's some weird residue on top of the solder mask?
If you guys hadn't asked a few questions I wouldn't have recovered these from the trash to try this! So, thanks everyone. This has saved me a fair bit of time and money.
This exact thing happened to me when cleaning an Atari 2600 motherboard with alcohol. Kept at it and it eventually all came off. Not sure what it was.
TKempkes wrote:
This exact thing happened to me when cleaning an Atari 2600 motherboard with alcohol. Kept at it and it eventually all came off. Not sure what it was.
Sounds like solder flux to me, Atari usually coated the undersides of 2600 motherboards with it.
ApolloBoy wrote:
Sounds like solder flux to me, Atari usually coated the undersides of 2600 motherboards with it.
Why?
Back on topic, I've had similar experiences with low-quality solder flux as well, especially the kind that is liquid at room temperature after heating. I've found that after desoldering components from a board that I used this flux on it was best to thoroughly scrub the board with warm water and a bit of dish soap (the kind that says it cuts grease) using a tea towel. If I skipped this step I often wouldn't get proper adhesion with the next solder I applied.
I never did scrub these with alcohol though, so I didn't get that creation of stickiness you describe. I tend to try dish soap first.
Maybe the alcohol is chemically reacting with the stuff?
I dunno, I'm not a chemist or an electrical engineer
I think I have experienced similar issue recently. I assembled a few pcb and they did not work correctly after eventhough the soldering job was very good. A week later I tried them and they worked on first try. I clean my board with 99% isopropyl too.