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Identifying type of solder

Discussion in 'General Electronics Chat' started by Hillbilly, Dec 9, 2009.

  1. Hillbilly

    Hillbilly New Member

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    I have a couple rolls of solder BUT there is no label on the spool to tell whether it is acid or rosin core.

    Rather than buy more solder (which I don't mind doing), is there a way to determine which type it is ... does the flux melt differently for example?

    Many thanks.
     
  2. Boncuk

    Boncuk New Member

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    I don't know if plumbers use soldering tin with an acid core - I doubt it. They normally use acid separately from the tin and a brush to prepare the material for soldering.

    You can make a smell test though. If the soldering tin causes slight smoke and smells a bit sweet it contains rosin.

    If it bytes the eyes it contains acid.

    Boncuk
     
  3. Sceadwian

    Sceadwian Banned

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    I don't know of any solders that have a built in acid core, I'm not even sure if it's possible because most acid fluxes are pastes. If you cut the solder and look at it's cross section and see a smaller tube in the middle it's should be rosin core.
     
    Last edited: Dec 9, 2009
  4. dave

    Dave New Member

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  5. Vizier87

    Vizier87 Active Member

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    What's the significance of choosing either?
     
  6. Sceadwian

    Sceadwian Banned

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    Acid flux can't be used on electronics generally... it's acidic, if it ever gets damp, or simply over time the acid in the flux (that's left on the surface) will corrode components and traces. The only way to avoid this is to use rosin flux (not as effective but on a clean solder joint it doesn't need to be) or wash the flux residue away after use, which has all it's own problems.
     
  7. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Acid core solder is made and relatively common. I have some. Check out:McMaster-Carr

    See: part numbers 7658A(x)

    John
     
  8. Mr RB

    Mr RB Well-Known Member

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    Acid core is very rare in fine solder on reels!

    With rosin core the flux will build up on your PCB and quickly cool to form a hard deposit usually clearish or browny colour (it can then be chipped off).
     
  9. Boncuk

    Boncuk New Member

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    The most significant difference is increasing sales. :D

    Using acid instead of rosin you've made a circuit with self-destruction ability. :)

    Boncuk
     
  10. Vizier87

    Vizier87 Active Member

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    Touche, Hans. It's like those tech guys who flood their PCB with goo to prevent people reverse engineering their stuff. Goons.
     
  11. mneary

    mneary New Member

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    "Active" flux is used a lot in mass production. Don't know what the pH is, but it attracts moisture and promotes corrosion. The benefit is, that it washes off with water instead of requiring VOCs, or CFCs. Yes, it must be washed and dried thoroughly but it is commonplace.

    You can tell if a manufactured product has no flux residue, it probably didn't use the old fashioned rosin.
     
  12. Boncuk

    Boncuk New Member

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    I remember the early days of "flux" inside the solder. It was "Kolophonium" (colophony), a syrup like juice coming from the stems of pine trees.

    Violine players use colophony to wax their bows.

    Boncuk
     
    Last edited: Dec 10, 2009
  13. stevez

    stevez Active Member

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    My experience, for what it's worth: rosin or acid core flux solder was common and abundant (probably still is) in the larger sizes, such as one might use in plumbing. I've not seen acid core solder in the smaller gages though it may be available.
     
  14. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Small and large are somewhat hard to measure. :D

    The acid core solders I have are 0.062" and 0.038". The latter is a little finer than a very old spool of rosin core solder that I have for TH construction. True, I have not seen acid-core solder in the very fine (0.015") size used for SMD.

    The point is, acid core solders do exist, and the distinction between paste and liquid fluxes is irrelevant with respect to whether the flux is acid, rosin, or organic base. BTW, the acid in low-temp fluxes is often zinc chloride or a similar acidic salt in paste.

    A simple test for acid or chloride should help distinguish the solders.

    John
     

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