WORKSHOP VIDEO #20: Flux-off part 2, more flux reviews

This week the flux-off solder flux comparison returns. Our everyday Edsyn FL-22 goes head to head with two AMTECH syringe fluxes in the TQFP arena. Just for fun, we also tried to solder with shards from a solid rosin block. Find out which flux reigns supreme.

Special thanks to Sjaak for the AMTECH “China” flux.

Check out our previous Flux comparison video, and all our previous workshop videos.

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  1. The other question i always have with flux is how well you can clean the board after soldering.
    Can you use just water or do you need alcohol or even acetone?

    1. high concentration (90%+) isopropyl alcohol is your best bet, apply it gently with a brush until the board is cleans up, then put a tissue over the board and move the brush over the tissue, (might need to repeat a few times).

    2. Yeah, that is something i also wanted to ask.
      It’s very important for most of us to know if it leaves recidues and if its recidues are easy to clean.

    3. Great question. I will be sure to test this from now on, and revisit all the fluxes we tried to date.

      FWIW: I use (acetone or non-acetone) nail polish remover to clean all my boards. I use a toothbrush to get the flux out from between pins and make everything shiny. Wipe clean with a paper towel as best possible. As always, WEAR SAFETY GLASSES! Little bits of acetone will fly off the brush everywhere.

      1. It seems I stand corrected. I always thought that acetone was too strong for PCBs.

        Acetone does leave behind a residue though, so if you use it, you should probably follow that up with some isopropanol.

    1. hehe, I did notice that in editing too. My fist syringe of flux was 10 years expired when I bought it, but still worked great for another 10. Now it lives on arakis’ workshop still :)

    1. It looks like he scratched off some silk to keep it secret. It appears to have arduino shield connector pattern. I see 2 encoders, a display, a 20pin soic that appears to be level shifting between the pic and the arduino. an 8 pin soic that appears to serial ram. There is a pretty beefy vreg. I love a good mystery…. this is fun!……

      2, encoders, a display, a 16bit pic all on an arduino shield….I wonder what value the arduino brings, hardly seem needed with all that power :) I can’t wait to find out what it is

    2. This is one of the rare projects that we did not develop in public. The reason is that it is so silly simple that we can’t believe nobody has done it already, and we’re so small it would be easy for someone to scoop us (er, maybe kickstart us is more relevant these days). Once it is in production then it’s probably safe to start talking :)

  2. Would I be completely spoiling the surprise if I asked if that was a PIC24FJ256DA on there?

    1. Dolabra, nice findings. I think, it is a pic-duino itself and not a shield because it has got a usb connector too.

      My guess is some sort of pic-duino joystick!! with display … some gaming stuff!!

      Ian, whatever it is, it looks cool.

      1. My wife says I always spoil xmas by guessing my gifts, so I should stop speculating and let Ian develop his product.

  3. If acetone kills your lot lacquer or your silk, change the fab where you make them as they don’t get their job done. Problem with acetone is that it will eat up some of the plastic on board (some connectors will be soften/eaten), but most plastic on board (99.9%) is PP/PE and those are ignoring acetone. Anyhow since 99.9999% of fluxes are based either on IPA or water using IPA to clean your board is best option. (using toothbrush to clean between legs).

    Note that there’s 3 reason ppl clean flux residue
    1. it looks ugly (if you don’t care about visuals ..)
    2. some flux’s (the strong stuff like cinol paste that contains zinc chloride) are conductive on high frequencies so if you do not clean them you get very nasty surprises in production. Note that these are rarely used in past decade for electronics
    3. some flux’s are too aggressive and will corrode legs of your components over time.

    I can say that IPA+Rosin home made flux
    – leaves ugly residue (and smokes)
    – does not get conductive on high frequencies (tried up to GHz)
    – does not corrode your electronics

    So this type of flux you have to clean only for visual reasons, with regards to everything else, you can leave it as is.

    All the other types I always clean so I never let them on board long enough to know if they are corrosive, nor I tested them for high frequency conductivity (this syringe ones).

    As for those no-clean stuff in pen dispensers, I never found them usable …


    p.s. Ian, so you felt the smell of the “made in usa” one :D now you know why I don’t use them any more
    p.p.s. it’s weird that you need to wick the legs of the chip after using paste flux..

    1. One could probably add another reason for cleaning flux:
      – “dirt”/ingrediences in flux can act as resistance.

      I have killed one geiger muller counter with chineese cheap flux, that I didn’t clean-up.
      This was the case of the “third” flux in the video.

      Right now I am using “Chip quik” gel flux in siringe, and it works perfectly. And didn’t experience the problems as with the previous one.

  4. I have some MG Chemicals flux, both in syringe and marker form. Both of them work extremely well. You don’t press the tip down when you dispense it by the way, just to reload the tip. It’s good for when you want to carefully apply flux somewhere. I’d put them on par with your current champion flux, they also nearly have no odor as best I can tell. I’m fairly impressed with them, I think the point I’m trying to get at is as you’ve demonstrated not all fluxes are alike. Not all flux markers are rubbish!
    I prefer to use my marker since it leaves much less mess behind than the syringe, its a lot tidier and manageable.

      1. The pen is RA type Flux but its easily cleaned since you use so little of it. The syringe is No-Clean.

    1. I just read the datasheets on the flux markers from the other video, which is “RMA” type flux which is only partially active which is why cleaning is optional.

  5. Did you ever use/ evaluate a flux called “Super Goot”?
    I see it on Ebay and saw you mentioned the Goot brand during on of your trips

  6. what is the use of flux type 223 I tried to reball with it but failed 1st I used to reball bga with ppd it was fine but now I cant is it same material

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