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Good soldering flux?

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elektryk:
Which flux has actually the best price vs quality ratio?
I have been using Kester TSF6502, it was nice but now it has poor availability in my country.
Some years ago I've also bought Kingbo RMA218 from China, it needs cleaning but worked also good. I've bought it again recently but unfortunatelly some ingredients (or manufacturer) must have changed and now it works very poorly (I even stopped using it).
I'm currently using Alpha OM338, it is active enough and easy to clean, it could be the best of mentioned here but the smell of it is in my opinion terrible. It'd  be nice to find something similiar but with less aggressive fumes...

wraper:

--- Quote from: elektryk on December 22, 2023, 09:40:33 am ---Some years ago I've also bought Kingbo RMA218 from China, it needs cleaning but worked also good. I've bought it again recently but unfortunatelly some ingredients (or manufacturer) must have changed and now it works very poorly (I even stopped using it).

--- End quote ---
It's not even clear who made the original thing, not to say 100 of its counterfeits.

T3sl4co1l:
Beats me -- as mentioned, you get whatever you get from China, if it's anything at all like the name (let alone datasheet) suggests, or actually similar to some other name-brand product they're aping, who knows.

A good general strategy with such markets is: consider your money wasted.  Don't spend any more than you can afford to simply and completely throw away.  Anything you get in return, is then a welcome surprise, a gift to yourself as it were.  There's nothing to be disappointed by, because you already threw away the money.  Right?  So, if you get a product roughly as described (it's flux, but not the right kind), that's a pleasant surprise; and if it's exactly what you wanted, a remarkable surprise!

Even if such products are, you know, just a couple bucks each, but to get some modest degree of confidence that you're buying at least one of the thing you want, you should plan to purchase several at once, from a diversity of suppliers, across marketplaces (shop on Ali and Amazon and etc.; try to make sure they aren't all myriad storefronts of the same underlying companies -- gibberish brandings proliferate).  And since the results of such a purchasing campaign will vary from trial to trial, if you need a certain quantity of that product, you should further plan on buying multiple at a time -- so you have a reasonable supply until the next time you need to do the same thing.

Maybe you can buy one of everything and go back and get more of the one thing that worked, but you don't know what the chances are, of the storefront remaining up at all, or the product being the same next time.

So, you can see it quickly adds up to an expensive endeavor, both financially and in terms of time spent shopping and reviewing/testing.

The cost of a name-brand product feels much less painful, all considered.

To that end, I'm currently using a tube of this, https://www.digikey.com/en/products/detail/chip-quik-inc/SMD291/355201 and it's lasted over a year so far (maybe a couple? I forget when I got it), so, that $15 price tag is well more than amortized to me.

Tim

shapirus:

--- Quote from: elektryk on December 22, 2023, 09:40:33 am ---Which flux has actually the best price vs quality ratio?

--- End quote ---
I'd say it mostly depends on your local availability, unless you're willing to pay for shipping and/or minimum order to get something well-known from global stores like mouser, digikey etc.

Otherwise, we can discuss what's available on aliexpress, but often times the impressions about a specific product stay relevant for only so long, because at some point the product can change, and they will sell a completely different stuff with the same sticker.

FWIW, for now, I'm half satisfied with Mechanic (that's at least somewhat of a brand) 223 and 225. I don't see any real difference between them.
What I like: they work well for soldering. They don't leave burnt hard to remove residue. They don't conduct. They don't cause corrosion (the "copper plate in the bathroom" test).
What I don't like: the fumes are stinky, which is perhaps a good thing, as it forces you to use a fume extractor or at least a fan to blow or pull them away from direct inhaling. They are somewhat stubborn to clean: need to be left soaking in IPA for some time, then they become gel-like and can be removed with a brush, but even then, after drying, some white powder-like substance remains stuck in hard to reach spots. I'd much prefer something that is diluted and not just thinned by IPA.

There is also that fake "NC-559-ASM-UV" from ali. Non-corrosive, too. Works well for soldering, easier to clean than the two mechanics mentioned above, but is a bit conductive: few GOhm at low voltage with 1-2 mm between the leads. Some would say that the fluxes conductivity is to be measured after heating. I would answer that it does not apply for hand soldering: you can't heat all of the flux and some will remain trapped in hard to reach spots, which may cause issues in high impedance circuits. Therefore zero conductivity both before and after heating is important.

I have ordered one more from ali: the "Relife Green". It hasn't arrived yet. There are hopes that it may turn out good, will see. It is also somewhat of a brand name, so lower risk of getting a different stuff under the same name.

Also worth watching, even if old:

elektryk:
Yea, no risk no fun...
I know a company where they tried to incorporate some charger modules from China, the funny thing was that with each delivery they got something different and then abandoned this idea.

Is that SMD921 active enough to solder so-called NOS components? I've got a bunch of old components with oxidized legs. Especially silver plated ones can be difficult to solder.

Anybody tried this?
https://www2.mouser.com/ProductDetail/Chip-Quik/CQ4300-2OZ?qs=Wj%2FVkw3K%252BMDhZZtwx%2F2ZXA%3D%3D
https://www2.mouser.com/ProductDetail/MG-Chemicals/8342-50G?qs=6SAGcVcpVil6QxsjfUWJgQ%3D%3D


shapirus I've seen that video but I'm also afraid that the same situation will occur like with my RMA218 but with such price I can buy sth. to test it.

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