Is Amtech Flux really worth the extra over other fluxes? A comparison

[SteveyG]

[testpoint1]

if that is Chinese brand "Amtech", that means to do the test, if like this:
https://www.ebay.com/itm/AMTECH-NC-559-ASM-No-Clean-Tacky-Gel-Solder-Flux-10cc-X2-Kit/202683137432

the "Amtech" is NOT real Amtech, this is someone registered it in China, then spread to the world now.

[Ian.M]

The test quite clearly covered both real and fake "Amtech", so I don't understand what point you are trying to make?

There wasn't a whole lot of variation except in general usability and ease of cleanup.  I suspect that with a fresh ENIG finish PCB and fresh ICs, and with so much flux used, even plain tallow would work well enough.   

It would be interesting to see how the same fluxes compare if used more sparingly on an immersion tin finish PCB that had been lightly weathered by either ageing or by repeatedly wetting it with tapwater and allowing it to air dry.  It would also be interesting to compare the difficulty of cleanup in more detail.

[floobydust]

Amtech seems to have crappy distribution, I don't see it for sale anywhere other than eBay 
Louis Rossmann (Group) never has it in stock and just teases everyone by using it in his videos.

If only Kester made some gel flux.

[KL27x]

Why would/should anyone expect Amtech flux to be better than any other reputable flux? Is this the Louis Rossman effect? Or does Amtech have some long-standing reputation in your circle?

If only Kester made some gel flux.

Once you start heating your gel flux, it turns to liquid and runs all over, anyway. The main reason to use it is the slower evaporation/boiling-off rate. The problem I have more often than not is that the flux doesn't dry out fast enough. AFAIK, gel flux was made for hot air reflow of BGA, due to the long ramp up. But if you're gonna clean the PCB after, I suppose this is what helps it to clean so easy. It's still wet.

[3roomlab]

no clean flux leakage current plot

[floobydust]

What strange graphs, 3(a) almost 100mA leakage current at a few volts for wet glutaric acid? Soaking something and measuring leakage seems pointless. No-clean is known terrible for high voltage, with high  leakage currents and other oddball phenomena.

Amtech made by Inventec USA with no distributors in Canada so they can suck it Trebek.

One drop of flux runs all across a pcb, leaving a too thin film, I find. This is why the tacky fluxes are a bit better. Rossmann uses a continental amount though, almost cringe worthy 

[wraper]

No-clean is known terrible for high voltage, with high  leakage currents and other oddball phenomena.

It's a pretty bold claim. The only thing no-clean means is that it does not require cleaning and usually has low residue. Otherwise they are completely different fluxes, some are rosin based, some synthetic. Some are noticeably conductive in non activated state, some are not. Also proper usage is very important. If flux is not properly heated like during hand soldering, it may remain conductive. Especially important with SMD soldering. So if you hand solder, it's important to check if flux is not conductive in non activated state, especially if it'a a gel flux. For example in non activated state Chip Quik SMD291 is conductive but alpha OM-338 or Edsyn FL22 are not, all of them are no-clean.

[floobydust]

For high voltage and through-hole, I spec (water-soluble) with a board wash even though people complain it's costly.
Otherwise, I'm always staring at flux residue that endangers creepage requirements.
It might be the CM's paste is crap, how much residue to expect I'm not sure.

Then I found no-clean flux residue conductivity is non-linear, it's not a simple resistance. It shows up on microwave and high impedance circuits (several megohm), worse with humidity. A good water or IPA wash and dry, many problems fixed, so these are my experiences.

No-clean seems fine for low cost consumer goods but the residue I always clean off after rework.