Author Topic: Make your own flux?  (Read 22881 times)

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Offline KL27x

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Re: Make your own flux?
« Reply #25 on: January 19, 2016, 12:24:39 am »
Quote
and halides. The last I haven't found what is.
Halides are ionic compounds that include an element from the halide column, the most typical in fluxes being zinc chloride.

Zinc chloride dissociates at soldering temp and becomes acidic. It basically turns into hydrochloric acid. The chloride ions have the tendency to borrow the electron from neighboring water molecules and/or other agreeable hydrocarbons, increasing the probability of a free proton in any given space at any given time, which is essentially what acidity is.

Halides are among the most corrosive part of a flux. Definitely not a first choice for electrical work, although plenty of electric fluxes contain some zinc chloride. (Zinc chloride is the main ingredient in plumbers flux). These halides essentially leave salt behind in the residue, and it embeds in the pores of the metal. It cannot be effectively cleaned away. This is a problem on ferrous metals, in particular. If you have ever tried to clean rusty metal with HCl, you know this is not a good method. You will get the metal sparkly clean, but no matter how well you wash it, it will rust within days.

As for making your own flux with acid and alcohol, that is fine. But you probably ought to clean the board after. What makes rosin so special it is made from super long chain acids. The rosin is at once the acid that dissolves the metal oxides and the residue that binds the end products. It just happens that rosin is acidic enough to dissolve copper oxide, and that it is a viscous fluid which is very liquid at 150+C but essentially solid and highly insoluble in water at under 50C.

Some of the rosin-free no-cleans work on the same principle, of leaving a hard, non-hygroscopic residue. Others are deemed no-clean for having a very low solids content (and therefor also a very low activity), so that when the carrier is completely evaporated there's not enough "crap" leftover to be problematic.


« Last Edit: January 19, 2016, 01:52:26 am by KL27x »
 

Offline Halvmand

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Re: Make your own flux?
« Reply #26 on: January 19, 2016, 03:02:08 pm »
KL27x:Good explanation. That makes sense.

My citric acid / alcohol flux was just an experiment to see if citric acid worked as a flux. It haven't shown signs of corrosion yet, but i think you're right, cleaning it off the board is a good idea.
 

Offline MrSlack

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Re: Make your own flux?
« Reply #27 on: January 19, 2016, 04:18:38 pm »
KL27x:Good explanation. That makes sense.

My citric acid / alcohol flux was just an experiment to see if citric acid worked as a flux. It haven't shown signs of corrosion yet, but i think you're right, cleaning it off the board is a good idea.

Definitely want to clean it off. You can etch boards with citric acid.
 

Offline KL27x

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Re: Make your own flux?
« Reply #28 on: January 19, 2016, 08:44:47 pm »
Personally, my more immediate concern is that citric acid flux residue could be measurably conductive from humidity in the air.

All fluxes dissolve metal oxides, and therefore they could all theoretically (in combination with an oxider and in sufficient quantity - an in some cases sufficient temperature) etch a board, if you were determined to do it.

I don't know of a reason that citric acid residue would be particularly corrosive, other than every water soluble flux residue should be cleaned off for the potential conductivity. Continued corrosion is certainly a concern. If you want to completely erode a copper trace on your powered circuit board, human sweat is about as bad as anything, largely because of the halides and the water.
« Last Edit: January 19, 2016, 09:22:56 pm by KL27x »
 

Offline KL27x

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Re: Make your own flux?
« Reply #29 on: January 20, 2016, 07:53:05 pm »
No clean is a rating? It seems kinda of like it's a category of fluxes, and I don't really agree with it, always.

E.g. rosin and RMA and RA are not called "no clean," but the description of them usually says something to the effect of non-conductive, non-corrosive, and/or "residue may be left on non-critical circuitry."

The fact that RA does not meet milspec unless the residue is washed off does not bother me, either. Rosin fluxes are the ONLY fluxes that meet milspec, at all. I'm sure one day I will have a problem from RA residue (RF signals, perhaps). But if I can't measure conductivity and my circuits work, I can't see a problem.

I do not really care what the manufacturer says about a flux. I have my own understanding. I do my own testing. And I come to my own conclusions. I clean my boards when they need to be cleaned. Esthestically, I don't care unless the residue interferes with inspection. As long as the residue does not collect dirt/dust nor is it conductive or corrosive. All of the rosin fluxes meet my own personal standard of "no clean," and they also meet my personal standards or being easily cleaned, if I want. Only some of the manufacturer branded "no clean" products meet my own personal standards.
« Last Edit: January 20, 2016, 08:06:16 pm by KL27x »
 

Offline free_electron

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Re: Make your own flux?
« Reply #30 on: January 20, 2016, 08:28:29 pm »
real men grow their own pines, topple them by biting through them with their teeth , grow their own corn to distill the alcohol. ( in a hand build distillery system by digging their own copper ore , smelting it and forging the kettle and cooler spiral from it. )

wimps with their rosin stuffed solder core..
Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Offline TechItApartTopic starter

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Re: Make your own flux?
« Reply #31 on: January 21, 2016, 03:30:20 pm »
So many replies, awesome. I think I will have a go at doing it. I've bought 100g of "best quality pine resin" from eBay for cheap. Will post back with results.
 

Offline RobertBG

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Re: Make your own flux?
« Reply #32 on: January 21, 2016, 04:13:44 pm »
I did it once at 1 am when I ran out of flux.I simply used rosin from my sisters violin and alcohol but after finding out what it cost to replace a small tin of the stuff I wont be doing it again  :palm:  I forget the size but it couldnt have been more than 80-100 grams and it was 30$ or so at Guitar center lol.Needless to say it was a expensive experiment :D in hindsight I think a pinch of the rosin and a eye dropper would've got me through the night without my sis knowing.
 

Offline macboy

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Re: Make your own flux?
« Reply #33 on: January 21, 2016, 05:36:14 pm »
So many replies, awesome. I think I will have a go at doing it. I've bought 100g of "best quality pine resin" from eBay for cheap. Will post back with results.
You didn't buy the raw stuff that people use as incense did you? Don't use that. Buy the refined stuff in the little cardboard carton. Look for one that is as light colored as possible.
 

Offline nanofrog

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Re: Make your own flux?
« Reply #34 on: January 21, 2016, 08:06:20 pm »
Buy the refined stuff in the little cardboard carton. Look for one that is as light colored as possible.
FWIW, there's some that comes in metal tins as well (usually Russian made, but I've seen some Polish, Romanian, and even German made on occasion as well). Looks rather decent too based on eBay photos.  :-+

There's also some solid RMA in tins (RA too, and Polish made IIRC), that you could solve into a liquid using alcohol or acetone (or a mixture of both). Not sure it's all that cost effective though, so I never bothered to try it out.  :-// Easier, more convenient, and cost effective to buy MG Chemicals 835 IME (or Kester 186 in small bottles from Dickie's Garage Sale for those in North America). 

Skycraft Surplus breaks down Kester 1544 into ~2oz. for $3.95, though I suspect you'd only be able to get this in person (i.e. bottles could leak during shipping, and they don't want the hassle). But if you're ever in Orlando, FL, the place is worth a look if you've the time.  :-+
 

Offline rdl

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Re: Make your own flux?
« Reply #35 on: January 22, 2016, 02:00:07 am »
Youtube Cody's Lab.

Thanks for that.

I just watched all the "Cody's Mine" episodes. I'd never even consider attempting a project like that, but he just decided it might be cool and started digging. I'll definitely be watching his other more "sciency" stuff.
 


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