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Soldering flux recommendations

Discussion in 'Electronic Design' started by cameo, Feb 21, 2013.

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  1. cameo

    cameo Guest

    I haven't bought any soldering supplies lately and am not familiar with
    the latest best products. Can anybody recommend some good lead-free flux
    that's easy to work with and is widely available in the US?
  2. I think pretty much all flux is lead-free.

    But, try this (some of the items are flux remover):-

    Best regards,
    Spehro Pefhany
  3. Guest

  4. Syd Rumpo

    Syd Rumpo Guest

    I use ordinary plumbing flux for lead-free plumbing[1] applied with a
    toothpick or small brush. It works very well for prototyping, a small
    tub will last for years, but I guess it wouldn't be approved for

    [1] You can't have lead-free 'plumbing'. Plumbers should now be called
    'tinkers' and what they do, 'tinkering'.

  5. Syd Rumpo

    Syd Rumpo Guest

    This is what I use, and I've been doing so for years...

    ....yes it's aggressive and, like I said, not for production. For
    prototype building and rework it's really very good indeed.

  6. Syd Rumpo

    Syd Rumpo Guest

    The stuff I use doesn't affect the soldering bits at all, as far as I
    can see. I use it because it's so good, and better than the pen stuff
    I've tried. The manufacturer describes it as a 'medium active' flux.
    It's a colourless translucent paste.

    A quick wipe of this over SMD legs and solder wick becomes almost
    magical in its suckiness and the solder flows like mercury.

    But again, not for production.

  7. SoothSayer

    SoothSayer Guest

    If you guys are having a problem with "prototype building and rework"
    having a need for an aggressive flux, then you have serious component age

    Snip back the first inch of any cable you have which you intend to use
    to fabricate an interlink with. If it is old cable.

    Modern soldering is easy, and I have never seen the need to use any
    such aggressive flux to wet a connection.

    Either the wire is too old, or your understanding (lack of) of thermal
    masses is lacking, or both.

    I have found that silver plated mil wires and cables are far easier to
    work with than tin plated stuff.

    Tin plated HV cable acts like it was coated with ultra-ever-dry. Very
    hard to wet, but still doable. I always spec the SPC stuff.
  8. Tim Williams

    Tim Williams Guest

    I have some *nickel* plated mil spec telfon (mineral loaded, high temp)
    wire. It takes for damned ever to tin the stuff. It's also about 10AWG.

  9. Tim Williams

    Tim Williams Guest

    Funny, I just did a little maintenance on my V-7A. Replaced the PS diode
    (encapsulated Se), filter cap (no sign of trouble with either, just wanted
    to change them), and AC coupling cap (molded axial, the kind that
    sometimes goes bad), and calibrated it so it's within a few percent again
    on most ranges. Still needs some Deoxit on the switches, and fresh oil in
    the movement, but it's reasonable otherwise.

    One advantage of this unit over most DMMs is the AC bandwidth -- it's flat
    out to about a MHz, probably further with transmission line (I've got
    stray banana jack cables going to it and see some zeroes in the MHz band).
    Most DMMs I've seen roll off at a few kHz, not even enough for audio
    applications! The manual warns that, although it may work out to 7MHz or
    so, the loading will be significant up there.

  10. Guest

    You might increase the size of the AC coupling cap. As built the AC
    bandwidth is not flat down to 60 hz.

  11. You're not supposed to tin it. You're supposed to crimp it with a
    really expensive tool.

    Best regards,
    Spehro Pefhany
  12. Tim Williams

    Tim Williams Guest

    I'd noticed that. I calibrated AC at 600Hz. It drops off noticably by
    only 100Hz, so the 120V line is only "100V". Don't think I have any 0.1
    1600V handy though (it uses a 0.01).

  13. Guest

    If you paralleled the 0.01 with another that size , it would help a
    lot. Should move that drop at 100 hz to 50 hz.

    I have a few 1 ufd 2100 volt caps in my junk box from junked
    microwave ovens, but I do not think one would fit inside the case.

  14. whit3rd

    whit3rd Guest

    Nickel alloys (also found in thermocouple wire and battery terminals)
    soft-solder well, but the flux should be the acid type; anything recommended
    for stainless steel will work fine.

    The common type includes some sulfuric and hydrochloric acid; keep
    it well away from anything that can rust (there's some fumes emitted).
    It doesn't take much flux, just a drop on a toothpick. The toothpick
    will blacken and turn to goo after a minute, though.
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