How do you remove flux residue after soldering?

777funk · 12th May 2009, 11:02 PM

I'm changing out some SOIC surface mount opamps on a I/O for my recording setup. I'm having a problem with a mess of flux surrounding everything I unsoldered installed the new part and resoldered. How do I remove the flux?

I've heard flux residue can cause hiss in low signal sections of amps. I do not want hiss.

Forgive me if this is a dumb quesiton. I honestly haven't found any good/safe way to remove flux residue.

thanks!
Nick

Zero Cool · 12th May 2009, 11:06 PM

I use a small screw driver and carefully chip away the large deposits the best i can. then use a brush to wipe them away. then i use Alcohol and a q-tip to remove the rest of the residue. or sometimes a toothbrush to scrub it away. works well.

Cal Weldon · 12th May 2009, 11:15 PM

If you have used alcohol and a toothbrush and the residue remains you may need to use an ultrasonic bath. (usually not necessary)

EDIT: Missed Zero Cool's post.

grjr · 12th May 2009, 11:39 PM

I like to use acetone (nail polish remover) because it is a lot faster at dissolving flux than alcohol

Cal Weldon · 13th May 2009, 12:52 AM

Acetone will work faster but leaves a residue itself. I guess one could then wipe with alcohol if needed.

Sam Lord · 13th May 2009, 03:52 AM

Try Everclear (95% ethanol solution). Danger, highly flammable, store safely, use with great caution. Use a needle dropper to apply. Works great, nontoxic when inhaled up to a point.

nikwal · 13th May 2009, 10:41 AM

We've always used acetone at work(real acetone not nail polish remover with oil). and a couple of theese http://www.rolexreferencepage.com/articles/qtip.jpg made of wood..
You can use a plastic esd safe stick to remove hard residue. and if you want to use a brush, make sure its not dry.
Or you could have used another type of solder with another type of flux, and the problem would'nt be as big :-)

mjf · 13th May 2009, 10:30 PM

hello.
i used ipa cleaner (isopropanol) and a stiff brush........
greetings.............

MJL21193 · 13th May 2009, 11:14 PM

Lacquer thinner and toothbrush. Ultra effective.

A need to be careful with it though - it's poison and flammable, but so is isopropyl alcohol.

tsmith1315 · 13th May 2009, 11:35 PM

Quote:

Originally posted by Sam Lord
Try Everclear (95% ethanol solution).
...
Works great, nontoxic when inhaled up to a point.

Also works great for ingestion, and nontoxic up to a point for that as well.

12th May 2009, 11:02 PM	#1
777funk diyAudio Member Join Date: Feb 2007 Location: MO	How do you remove flux residue after soldering? I'm changing out some SOIC surface mount opamps on a I/O for my recording setup. I'm having a problem with a mess of flux surrounding everything I unsoldered installed the new part and resoldered. How do I remove the flux? I've heard flux residue can cause hiss in low signal sections of amps. I do not want hiss. Forgive me if this is a dumb quesiton. I honestly haven't found any good/safe way to remove flux residue. thanks! Nick __________________ Nick

12th May 2009, 11:15 PM	#3
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	If you have used alcohol and a toothbrush and the residue remains you may need to use an ultrasonic bath. (usually not necessary) EDIT: Missed Zero Cool's post. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

13th May 2009, 12:52 AM	#5
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	Acetone will work faster but leaves a residue itself. I guess one could then wipe with alcohol if needed. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

13th May 2009, 10:41 AM	#7
nikwal diyAudio Member Join Date: Aug 2005	We've always used acetone at work(real acetone not nail polish remover with oil). and a couple of theese http://www.rolexreferencepage.com/articles/qtip.jpg made of wood.. You can use a plastic esd safe stick to remove hard residue. and if you want to use a brush, make sure its not dry. Or you could have used another type of solder with another type of flux, and the problem would'nt be as big :-) __________________ http://dsl.mine.nu (very enironmental friendly 5watt damn small linux server made from a compaq t1010 terminal)..

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12th May 2009, 11:06 PM	#2
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	I use a small screw driver and carefully chip away the large deposits the best i can. then use a brush to wipe them away. then i use Alcohol and a q-tip to remove the rest of the residue. or sometimes a toothbrush to scrub it away. works well.

12th May 2009, 11:39 PM	#4
grjr diyAudio Member Join Date: Sep 2007	I like to use acetone (nail polish remover) because it is a lot faster at dissolving flux than alcohol

13th May 2009, 03:52 AM	#6
Sam Lord diyAudio Member Join Date: Jan 2007	Try Everclear (95% ethanol solution). Danger, highly flammable, store safely, use with great caution. Use a needle dropper to apply. Works great, nontoxic when inhaled up to a point.

13th May 2009, 10:30 PM	#8
mjf diyAudio Member Join Date: Jan 2009 Location: upper austria/near linz	hello. i used ipa cleaner (isopropanol) and a stiff brush........ greetings.............

13th May 2009, 11:14 PM	#9
MJL21193 Account disabled at member's request Join Date: Mar 2007	Lacquer thinner and toothbrush. Ultra effective. A need to be careful with it though - it's poison and flammable, but so is isopropyl alcohol.

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