My perfboards are sticky after cleaning. What am I doing wrong?

Using Arduino General Electronics
#1

Well, other than using perfboard at all. I really should learn CAD and have a few nice boards made. This last one had about 300 wired connections on it.

I solder with MG Sn63 / Pb37 No Clean. Then I scrub the back of the board with MG Isopropyl alcohol and a toothbrush and soak it with MG Flux Remover Spray, normal strength, not heavy duty. I soak it good and let it stream off, front and back (cleaning moves some of the dissolved flux to the front). But when it dries, the board is very sticky. I thought this was supposed to remove the dissolved flux. So I do it again, after the second dry the board is less sticky but not good enough IMHO. After the third time around it's good enough. Am I doing anything wrong? Should I be just using the MG Flux remover and forget the alcohol? The alcohol is less expensive, the spray is pricey. I don't want to use the heavy duty because I have 14 segment displays soldered to the board. Thanks.

#2

Could be a couple things. The flux may not be entirely removed, just getting diluted and spread around by the solvent. Sounds unlikely from your description. The other thing that comes to mind is something (other than flux) might actually be dissolving, which seems equally unlikely. Maybe the perfboard itself? Easy to check, try cleaning a virgin piece of perfboard.

I have good results using either denatured ethanol or CRC Brakleen. If you use Brakleen, be sure to use the red can (tetrachloroethylene), [u]not[/u] the green can, and you probably should use it outdoors. I thought isopropanol worked well also but I haven't actually tried it lately. I can usually find 99% isopropanol fairly readily, it's important not to use "rubbing alcohol" which is usually 70%-90% isopropanol, mixed with water and maybe other stuff.

#3

I noticed this before. Some veroboard essentially dissolves in the cleaning solution turning it sticky. Once that happens you can't actually get it clean - methylated spirits help, as does normal washing up liquid, but both wreck everything else on the board. After using it once, I gave up, and now just stick to IPA (Ispropyl Alcohol) if something needs cleaning - But I find even that leaves boards sticky as it just spreads the flux around.

#4

Funny how we insist on cleaning up after "no-clean" soldering. I do it too. Appearance is important I guess :D

#5

Yes, why even try to clean off no-clean flux?

In my experience [a lot of it], it’s not even worth trying to clean off solder flux, in
general. It works if you buy the right stuff, but now you have a local environmental
hazard site. How do you dispose of the horrible solvents and cleaning agents?
Professional companies have to deal with such problems in an ecological sound
manner - at least in the US. Can’t just dump that crap in the river anymore.

That being said, if I want nice looking boards, then I use water-soluable flux solder
in the first place. With this you can easily clean up the boards with moderately hot
distilled water and a toothbrush, and they are perfectly clean and non-sticky.

I leave off any components that might be affected by water [eg, electrolytic caps,
switches, etc], and solder them afterwards using no-clean solder [and leave the tiny
amount of no-clean flux in place].

#6

[quote author=Tom Carpenter link=topic=120500.msg906822#msg906822 date=1346177064] I noticed this before. Some veroboard essentially dissolves in the cleaning solution turning it sticky. Once that happens you can't actually get it clean [/quote]

This is actually "real" veroboard from the veroboard company, pad per hole FR-4 version. This: http://www.veroboard.com/4x10-4000d-epoxy-fiber-pitch-01-254mm-p-25.html

I will have to try this with a different board and see if it is as bad, or maybe clean the board before mounting and see if it happens. I hope it's not the board, they seem very nice otherwise and solder up very well.

#7

oric_dan(333): How do you dispose of the horrible solvents and cleaning agents? Professional companies have to deal with such problems in an ecological sound manner - at least in the US. Can't just dump that crap in the river anymore.

MG Flux Remover Spray is ethanol/isoproply alcohol/ethyl acetate and the isopropyl alcohol is just that to the tune of 99.94% according to the label. I clean the board on a piece of aluminum foil and whatever dries there (flux residue) I just crumple up and throw away. The alcohols and ethyl acetate evaporates, it's not that horrible.

oric_dan(333): That being said, if I want nice looking boards, then I use water-soluable flux solder in the first place. With this you can easily clean up the boards with moderately hot distilled water and a toothbrush, and they are perfectly clean and non-sticky.

What is a good solder to use for this method? I use http://www.mgchemicals.com/products/solder/leaded/sn63-pb37-no-clean-4860/ but I have no idea if the flux is water soluable or not.

#8

I just use a dry tooth brush to mechanically remove the dried flux, Turns it to kind of a fine dust, followed up with using a small amount of water and the tooth brush, seems to work fine for me. I tried Isopropyl alcohol (the pure stuff) and did find it often left a sticky film, so for me it's just water.

#9

retrolefty: I just use a dry tooth brush to mechanically remove the dried flux, Turns it to kind of a fine dust, followed up with using a small amount of water and the tooth brush, seems to work fine for me. I tried Isopropyl alcohol (the pure stuff) and did find it often left a sticky film, so for me it's just water.

OK, I am going to try that on the next veroboard and see how it looks under the loupe. Thanks!

#10

I assume no-clean is not water-soluble, else it would say water-soluble. Look up the latter at digikey.com or mouser.com. It's there. A little more expensive, but worth it.

The flux remover you have may be relatively environmentally friendly. Always good to look that stuff up.

http://www.cdc.gov/niosh/npg/npgd0260.html

Your method of disposal sounds pretty safe. You can do the same with old paints, etc. Brush onto newspaper, let dry so the nasty solvents all evaporate [air polllution is probably better than possible ground water pollution], and then send the newspaper to the landfill. Otherwise, supposed to take old paints and solvents to hazard recyclers.

#11

I see Kester makes a solder with a water-soluable flux

http://www.cmlsupply.com/kester-331-solder-1lb.html

This says that it is back to "must clean" because the flux is pretty active. However, it can be cleaned with water. I guess I should try this out.

#12

JoeN: What is a good solder to use for this method? I use http://www.mgchemicals.com/products/solder/leaded/sn63-pb37-no-clean-4860/ but I have no idea if the flux is water soluable or not.

Kester #331 is a 63/37 alloy with water-soluble flux. Haven't tried it myself, I use 245 and 275, both of which have no-clean fluxes, and I've been very happy with them.

#13

[quote author=Jack Christensen link=topic=120500.msg907000#msg907000 date=1346186307]

JoeN: What is a good solder to use for this method? I use http://www.mgchemicals.com/products/solder/leaded/sn63-pb37-no-clean-4860/ but I have no idea if the flux is water soluable or not.

Kester #331 is a 63/37 alloy with water-soluble flux. Haven't tried it myself, I use 245 and 275, both of which have no-clean fluxes, and I've been very happy with them. [/quote]

I have an itchy credit card trigger finger here. All-Spec has good prices on solder and I have bought from them before so I just got a roll of each of these. I am going to do a board with 331 and clean it with distilled water and see how that works out and do another with the 245 and try cleaning it with just a dry tooth brush, as another poster recommended. Thanks for all the suggestions.

#14

This says that it is back to "must clean" because the flux is pretty active.

Back?

The reason to go with water-soluble flux is so you can clean it off easily. Trust me [!!!], it's 10X easier to clean than the other stuff. And no mess afterwards to deal with. When I use the other stuff, I just leave the flux on [for years], cause it's such a PITA to clean off.

#15

JoeN: I have an itchy credit card trigger finger here. All-Spec has good prices on solder and I have bought from them before so I just got a roll of each of these. I am going to do a board with 331 and clean it with distilled water and see how that works out and do another with the 245 and try cleaning it with just a dry tooth brush, as another poster recommended. Thanks for all the suggestions.

Nothing like a little "retail therapy" :D Got mine at All-Spec as well. Have started tinkering with SMDs, the 0.020-inch solder works well, 0.015 might be a bit better, but then might be a little small for some other things. Also got flux pens and tweezers from them, I'm getting along well, but haven't tried anything smaller than 0805. Might be able to manage 0603, but certainly not anything smaller.

Cleaning the SMD boards after soldering by hand does make them look a lot better. Seems to work fairly easily either with ethanol or the tetrachlor.

#16

oric_dan(333):

This says that it is back to "must clean" because the flux is pretty active.

Back?

The reason to go with water-soluble flux is so you can clean it off easily. Trust me [!!!], it's 10X easier to clean than the other stuff. And no mess afterwards to deal with. When I use the other stuff, I just leave the flux on [for years], cause it's such a PITA to clean off.

I said "back" because you suggested not cleaning at all when using the "no clean" stuff and retrolefty suggested only a dry toothbrush. So it is going "back" to cleaning with the water soluble flux - just with water, which could be ideal if it avoids the sticky mess, it's quite cheap. Trust me, I love the idea so I am going to try it.

#17

Pure iso dries too quickly to allow the solvent to run off and take the sticky with it. Get the drug store 91% and hold the board vertical and keep dipping the tooth brush and scrubbing. The 91% has water in it that keeps it from drying off too quickly. That will allow it to shed off the board and take the sticky with it. I use this method with rosin core solder and rosin fluxes. YMMV.

Other than that, I do agree that the spray cleaners can sometimes eat the PCB material and make that sticky. Maybe that is what happened.

Good old electronic parts cleaner has never failed me though. Spray until it drips. Scrub. Spray again. Done.