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| Differences between different types of flux in solder? |
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| GoodCrossing:
I've been looking at this list of Multicore 60/40 rolls and I see there are many different types of what I presume is the flux inside the solder wire. I've cheched out the datasheet for the different types but I don't really understand it :P , so what's the difference, and do I need to choose which one to get or will they all work for general soldering? |
| IanB:
The best kind of flux to get for general soldering is probably "rosin, mildly activated" or "RMA". Another alternative would be "no-clean" flux. A kind of flux to avoid is "water soluble" as this flux needs to be washed off the board after you have finished soldering. |
| GoodCrossing:
Whoops, I thought I had attached the picture of the different types :palm: https://imgur.com/a/Lzk6p0F |
| helius:
Crystal is an activated rosin flux, with the different grades having different levels of halides. Halides are additives used to make brighter joints on oxidized metal surfaces: if you are soldering to new bright tin parts and new boards, you can use halide-free fluxes, while some halides make rework easier on old assemblies with oxidation or corrosion. Crystal 511 has 1.1% halides, Crystal 502 has 0.2%, and Crystal 400 has 0%. These would all be considered RMA fluxes (rosin, mildly activated), which don't necessarily need cleaning unless your process requires it. 362, 366, 311, and x39 are also activated rosin fluxes, which would be considered RMA or no-clean. They have various levels of activators, as described in the datasheets, for different application requirements. The above would all be suitable for normal hand soldering and rework. Hydro-X is water soluble ("organic") flux and should not be used unless you have extensive capabilities for cleaning and testing. The data sheet says that soldered assemblies need to be destructively tested for ionic contamination and the wash water conductivity monitored :palm: It seems to be made of citric acid in a glycerol and PEG carrier. Arax is an acid flux, made of ammonium chloride and ammonium fluoride in a urea buffer. Like all acid fluxes it is unsuitable for electronics. These ones would not be recommended. |
| schmitt trigger:
I also agree that for a hobbyist, it is best to use a no-clean flux. A washable flux, if washed incorrectly, can cause long term reliability issues. Some people have reported that they have washed boards using warm water with mild soap, scrubbing them with a clean toothbrush, and rinsing them in de-ionized water. The caveat I see here is the different tap water qualities around the world. Some locations have very hard water which could leave residues. Also some soaps, which are mostly intended for human use, have lotions and moisturizers. Again, it depends where in the world you get that soap, as formulations will vary. Therefore, stick with a no-clean flux. |
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