Probably a really silly question, but can excess flux cause a short circuit? Just trying to figure out the cause of a temporary short circuit...
Flux is non-conductive - at least at the supply voltages of a pedal.
Quote from: Mike B. on October 25, 2013, 11:17:46 AM
Flux is non-conductive - at least at the supply voltages of a pedal.
Thanks Mike, that makes sense. If there's loads of flux left on the board after soldering that I haven't cleaned off, small bits of cut-off metal from my work surface could stick more easily to it. That could explain the short.
What's the right thing to use for cleaning flux off a board? Would isopropanol do the trick?
Isopropyl alcohol works great, but try to get the 90% not the 70%. Also, I use an old toothbrush with the alcohol and scrub lightly on the board to make sure there aren't any tiny droplets of solder between the traces.
Yep, 90%+ purity isopropyl alcohol works well. It may take a few passes with it as it tends to leave the board a bit sticky.
Flux remover works better but is more expensive. I often use both. I start with flux remover to get most of it off and then do a second pass with alcohol.
I've got some 99.7% isopropyl alcohol and come to think of it I probably need a new toothbrush, so will clean my boards after soldering now. I'll look up flux cleaner (first time I heard of it!)
If it saves some time in the test stage it'll be well worth it, thanks guys!
If flux did short, I'd be in huge trouble!
Flux isn't really a big deal for operation unless you are doing RF/Microwave circuits and you are either using water/alcohol/rosin flux. You shouldn't be using Acid flux (as used for plumbing) because that stuff WILL eat your board and you will have a bad day.
Alcohol and a toothbrush is a popular way to remove flux. Bonus points for rinsing and then blowing off with compressed air.
I also find that Simple Green as a solution works awesome for removing flux. I have a cheap-o (Harbor Freight store) Ultrasonic cleaner which I use to clean PCB's along with Isopropyl or Simple Green diluted. Just make sure what you are putting in there is sealed. I try to take out ICs and any switches but most discrete components and transistors are fine in a bath. I make a solution, get the water heated, and toss the board in for a few minutes. Works great!
If you leave it on, no biggie. It just looks horrid.
Quote from: rullywowr on October 30, 2013, 06:56:13 PM
Flux isn't really a big deal for operation unless you are doing RF/Microwave circuits and you are either using water/alcohol/rosin flux. You shouldn't be using Acid flux (as used for plumbing) because that stuff WILL eat your board and you will have a bad day.
Alcohol and a toothbrush is a popular way to remove flux. Bonus points for rinsing and then blowing off with compressed air.
I also find that Simple Green as a solution works awesome for removing flux. I have a cheap-o (Harbor Freight store) Ultrasonic cleaner which I use to clean PCB's along with Isopropyl or Simple Green diluted. Just make sure what you are putting in there is sealed. I try to take out ICs and any switches but most discrete components and transistors are fine in a bath. I make a solution, get the water heated, and toss the board in for a few minutes. Works great!
If you leave it on, no biggie. It just looks horrid.
Yeah, flux can cause nightmares on RF boards. I have one at work that goes to the board house with strict No Clean / No Wash instructions. They want to wash everything because it looks better, so we have to make sure they don't forget that.
One of the electronics instructors where I work told me that although flux is non-conductive, over time it can pick up a bit of dust as it's just a tiny bit sticky. That can cause some slight noisiness. I just gently scrape it out anywhere it's touching two adjacent pads. I did not know about the bath idea! May have to try it at some point.
I'm just gonna piggyback here...
So what do you guys do after cleaning with IPA? Just dry it off or run it under some tap/distilled water as well?
I take a can of compressed air and blow out underneath all of the chips so that the flux that's been washed away doesn't stay trapped underneath.
Other than that, I usually just let it dry. If you do wash it with water, it's probably safer to use distilled.
For the little bit of flux i find, i pop it off with a dental pick, always found i was chasing my tail with the alcohol, keep needing more and more, the flux spreading further and further, sticky sticky sticky. Pop it free, brush it off with a cutoff little paint brush or compressed air, done. Works really well on solder lugs, eyelet and turrets.
dave
Quote from: muddyfox on December 22, 2013, 03:31:36 AM
I'm just gonna piggyback here...
So what do you guys do after cleaning with IPA? Just dry it off or run it under some tap/distilled water as well?
Dishwasher works great! No no no I'm joking I just let it air dry, doesn't take that long. I wouldn't run any water on it. Honestly I'd your solder contains flux, there's no real reason to worry about it.