Solder Flux Question....

Discussion in 'The Workbench' started by Gutch220, May 30, 2020.

  1. Gutch220

    Gutch220 Well-Known Member

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    So I've been using generic flux over the years without ever putting a lot of thought into the different kinds. I'd just buy whatever the local hardware store had.
    So I see that there's rosin flux, organic, inorganic, acid, in a jar, in a tube, activated, mildly activated, water-soluble, etc, etc.

    What's the best stuff/version to use on amps, guitar, effects, etc? (the stuff we talk about on this forum)
     
  2. Micky

    Micky Well-Known Member VIP Member

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    Rosin flux is for electronics.
    Usually you can use rosin core solder.
    There is also liquid rosin solder you can use.
    Rosin paste flux is used for placing SMD stuff and soldering it.

    Never use acid flux on electronics. Never.
     
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  3. Gutch220

    Gutch220 Well-Known Member

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    what about activated versus mildly activated?
     
  4. Micky

    Micky Well-Known Member VIP Member

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  5. Gutch220

    Gutch220 Well-Known Member

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    thanks. it sounds like I need either rosin flux paste or mildly-activated flux paste. which do you think is best to use/recommend? I'm leaning to regular rosin flux paste (not activated). I'm not sure how MUCH of a difference this will make though.
     
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    [​IMG] Alcohol based therefore clean with isopropyl 90% alcohol.
     
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  7. Micky

    Micky Well-Known Member VIP Member

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    I use a liquid flux in a small plastic dispenser bottle.
    2 maybe 4 ounces, with a small needle dispenser.
    I've had it for years, I forget the brand name, probably Kester.

    I don't use it much because I use rosin core solder.
     
  8. Gutch220

    Gutch220 Well-Known Member

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    hmm?..... [​IMG]
     
  9. Micky

    Micky Well-Known Member VIP Member

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    I don't have much use for paste flux.
    Only time I use paste is when I am soldering copper pipes.
    (yes, I do plumbing work too)

    Personally I think I you would be better off with a liquid flux.
    It is much easier to control how much you use.
    A little goes a long way...
     
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  10. thetragichero

    thetragichero Well-Known Member

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    I've had a think of radio shack paste flux that size for about a decade and it's finally almost gone. I'll definitely look at liquid next because the paste isn't very fun to work with
     
  11. Nik Henville

    Nik Henville Well-Known Member Premium Member

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    A
    Flux
    Capacitor
    is in the wrong thread... damn.

    :hippie::pirate::uk:
     
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  12. ampmadscientist

    ampmadscientist Well-Known Member

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    The flux is not for soldering.
    The solder already has flux in it.
    The flux is only for : DE-soldering.

    De soldering requires more flux and higher temperatures.

    And those who want to learn DE soldering, must learn to use the added flux.
     
  13. ampmadscientist

    ampmadscientist Well-Known Member

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    No don't use paste.
    Use liquid rosin flux made specifically for electronix, non-corrosive.
     
  14. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    There is no need to use anything but multi core solder, why use flux when the solder already has it in it.

    You must always take off all the old solder first before you reapply the new.

    I think the problem here is that so many try to do there own, or others, repairs and read loads of links concerning soldering etc, most of which are from guys that do not even know the basics of electronic servicing and repair.

    So its a case of the blind leading the blind.

    I can assure you guys that multi core solder is the only thing you need to work on electronic kit.
     
  15. ampmadscientist

    ampmadscientist Well-Known Member

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    The Flux Is for UN-soldering.------ Not soldering.
    The De-soldering Braid needs fresh flux to work properly. There is not enough fresh flux in the existing solder to make the braid work.
    Some fresh flux must be added, or the de-soldering braid doesn't work.

    2. The de-soldering braid must be clean shiny copper. If the copper is oxidized, the de-soldering won't work.

    3. It takes a higher temperature to DE-solder.
    Because the de-soldering braid copper is dissipating a lot of extra available heat.
    If there is not enough heat to compensate for the added copper braid heat dissipation, the de-soldering braid won't work.

    3 basic rules
    that make DE-soldering possible.
     
    Last edited: May 31, 2020
  16. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Were have you been all you life, thats a load of tosh.
     
  17. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    This is all you need to know, read and learn......

    In soldering of metals, flux serves a threefold purpose: it removes any oxidized metal from the surfaces to be soldered, seals out air thus preventing further oxidation, and by facilitating amalgamation improves wetting characteristics of the liquid solder.


    Do
    you need to use flux when soldering? When soldering circuit boards, or other electrical / electronic devices, yes - you need to use flux. Fortunately, almost all solder for electronics use has an internal core of flux, so you usually don't need to add more
     
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  18. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Simple explanation is that Flux is the glue in multi core solder that enables you to make a good clean electrical connection.
     
  19. ampmadscientist

    ampmadscientist Well-Known Member

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    De-soldering:
    It doesn't work unless you add more fresh flux.

    This is why so many people cannot de-solder.
     
  20. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Got nothing at all to do with de soldering, as long as you use a good clean iron, good quality braid, well impregnated, better still a good solder sucker, one attached to the end of you iron.

    Not unless i have been doing it all wrong for 57 years, the very first thing i was taught when i joined EMI at 16 was how to solder properly, that has been my bible throughout my whole working life in electronic repair.
     
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