help identify the flux used in this solder paste product

Thread Starter

mikewax

Joined Apr 11, 2016
139
Hello all, so i got this solder paste and wonder if anyone knows what type of flux it is made of.
couldn't find any MSDS. it's a 63/37 with melting point 183C.
paste.jpg
 

jpanhalt

Joined Jan 18, 2008
10,203
Unfortunately, the label on what you show doesn't match the description:
1585709930605.png

Moreover, 3 micron mesh is quite small. The popular Kester EP256 solder paste is 44 micron to 25 micron (i.e., -325/+500 mesh).

Chances are it is a generic flux which is also sold by the same company.
 

Thread Starter

mikewax

Joined Apr 11, 2016
139
Most likely rosin based. Are you trying to rejuvenate paste that is dried out?
no, i have a manufacturing process where i pre-tin the PCBs with the afore-mentioned paste, then i flux it over with ChipQwik tacky flux (see photo), then i place the board in my piknplace device, populate the board, then bake it.
the problem is that the ChipQwik tacky flux doesn't seem to be very compatible with the pre-tinned solder. when i bake it, it doesn't melt n flow at the same temperature. i don't wanna heat it that high, like 20-40 C higher. I'm baking each board twice and i want as low temperature as i can get.boards.jpg



the one on the right is tinned and fluxed
 

Thread Starter

mikewax

Joined Apr 11, 2016
139
Chances are it is a generic flux which is also sold by the same company.
well the company also has this but if i order some it will take 6-9 weeks to get it. i sure don't have that kinda time to wait. I just wish there was a way to find out what it is and get some. God knows there's almost as many fluxes as there are solders.
pic.jpg
 
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jpanhalt

Joined Jan 18, 2008
10,203
Chip-Quik sells 4 different tacky fluxes. Which one are you using? This one is recommended for leaded solder: https://www.chipquik.com/msds/RMA591.pdf It is a rosin/solvent based flux.

Your Mechanic material is sold by a lot of entities, but very little information on it. Is it water soluble? No clean? The title and picture you show do not match. Presumably, you have what is described in the title. Have you checked?
 

Thread Starter

mikewax

Joined Apr 11, 2016
139
Chip-Quik sells 4 different tacky fluxes. Which one are you using? This one is recommended for leaded solder: https://www.chipquik.com/msds/RMA591.pdf It is a rosin/solvent based flux.
damn i didn't know that. I'm using SMD291. i'll order it right now.
Your Mechanic material is sold by a lot of entities, but very little information on it.
yeah everybody and his mother slaps their own half-ass fake label on it, and nobody has an MSDS. But the stuff does work pretty well. I've used it before and i can tell it's the same stuff.
Is it water soluble? No clean?
HELL NO i have to cuss up a storm and scrub the LIVING CRAP out of it with IPA and a stiff-ass toothbrush. Scrub the damn thing until my arm falls off. Scrub until i'm long dead and gone. Last board i did i scrubed it for over 700 years.
 

dl324

Joined Mar 30, 2015
11,456
i have to [snip] scrub [snip] it with IPA and a stiff [snip] toothbrush.
Are you using 70% or something higher? Commercial flux remover works best but, to save money, I start with 70% IPA and finish with 90-99%. I only use the commercial remover when I'm sending a board to someone and don't want them thinking poorly of my workmanship.
 

jpanhalt

Joined Jan 18, 2008
10,203
That's odd. From a chemist's standpoint, I would go in the opposite direction. Why dilute your 99% stuff with water? A little water hurts a lot.

What I have found is that adding a little "Cellosolve" (alkoxyethanol) not only helps the good stuff, but will allow up to 50% water and still be effective. It's effective alone, but retail in small volumes runs about $20 for 500 ml. I prefer the ethoxyethanol because of its lower BP compared to the more common butoxyethanol, which is used in everything from paint vehicles/solvents to vinyl/linoleum floor was stripper. Smell Zep brand floor stripper and you will recognize the odor. They are also used in organic brake fluid (DOT 3...) because of high BP, stability, ability to dissolve and retain water, and low toxicity. Perhaps most important, they seem milder on cheap plastic (e.g., polystyrene, PVC, ABS) than acetone or MEK.
 

jpanhalt

Joined Jan 18, 2008
10,203
That's good. Don't you dip? If you want something that evaporates slowly, try brake fluid. Butoxyethanol is much cheaper than the ethoxy version and also evaporates quite slowly (BP about 171°C).
 

Thread Starter

mikewax

Joined Apr 11, 2016
139
That's good. Don't you dip? If you want something that evaporates slowly, try brake fluid. Butoxyethanol is much cheaper than the ethoxy version and also evaporates quite slowly (BP about 171°C).
does brake fluid work as well as 70% IPA? and where do you get Butoxyethanol? i never heard of it.
 

jpanhalt

Joined Jan 18, 2008
10,203
1) I don't use brake fluid.* Alkoxy alcohols are used in them. They are designed not to be volatile and have other useful properties as mentioned.
2) I consider 70% IPA to be rather poor. I use ethanol.
3) Butoxyethanol? Read the labels on floor cleaners and other similar products. It is likely to be listed as butyl cellosolve, but by any other name, it smells the same. Or, should that be "smell as sweet?" :) Got 2 gallons cheap at a Sherwin Williams paint store (professional, not consumer grade). It is used in a lot of things. However, it is slower evaporating than ethoxyethanol (171° v. 130(something)°C). For the time being, I am using ethanol (absolute) or IPA (95% to 99%) with about 10% ethoxyethanol.

If you are into trying stuff, I would also try diacetone alcohol. You have probably never heard of it either, but if you read labels, it is there. Might have to go to the MSDS, SDS, or similar. Some people say it is odorless. It is widely used and boils at 166°C. (https://en.wikipedia.org/wiki/Diacetone_alcohol) It is quite non-toxic and is/was even used in dry markers (aka magic markers).

When I say read the "label," I mean read the product label, which probably has very little useful information, and the MSDS or other required "label" that actually says what is in something. I stay away from products that list contents as mostly "proprietary." That does not mean they are unique or "powerful." It can mean the composition is simply dish soap plus some scent that the manufacturer doesn't want to disclose.

*Edit: DOT3 is a performance standard. Not all DOT3 brake fluids have the same composition. Compare Wagner/NAPA to no-brand varieties.
 
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