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SMT handy soldering question

Discussion in 'Electronic Design' started by Sean Chen, May 30, 2004.

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  1. Sean Chen

    Sean Chen Guest

    Hi,

    I am interested in SMT handy soldering for fine pitch IC. Some people use a
    solder called Water Soluble Paste and oven to handle it. My question is:
    1. How many ICs can be soldered (approximate for 64pin PQFP) by a 35gm
    syringe solder ?
    2. Is any other cheaper solder or method can do the same thing ?

    Thanks.

    Sean
     
  2. maxfoo

    maxfoo Guest

    Have the pcb manufacturer make you a stencil to spread the solder paste. it's
    quicker and more precise than using a syringe.

    Remove "HeadFromButt", before replying by email.
     
  3. Leon Heller

    Leon Heller Guest

    Drag soldering works very well for fine pitch devices. I use a Metcal system
    with a 'mini hoof' tip made specifically for this technique, but an ordinary
    soldering iron can be used. You first apply plenty of flux to the leads. You
    then apply some solder to the tip and wipe it across the leads, one side at
    a time. Any excess may be cleaned up with desolder braid.

    Leon
     
  4. Leon Heller

    Leon Heller Guest

    Drag soldering works very well for fine pitch devices. I use a Metcal system
    with a 'mini hoof' tip made specifically for this technique, but an ordinary
    soldering iron can be used. You first apply plenty of flux to the leads. You
    then apply some solder to the tip and wipe it across the leads, one side at
    a time. Any excess may be cleaned up with desolder braid.

    Leon
     
  5. Yes, use 0.8mm to 1mm normal solder with some flux gel.
    Yes, the tip of the iron is wider than 2 pins are appart,
    but the flux drives the tin out. I also made good experiences
    with a 5mm diameter concave iron. Its tin depot lasted for
    32 pins in a row.

    Rene
     
  6. Terry Given

    Terry Given Guest

    I love my metcal :)

    Actually with plenty of flux its quite easy to use a fine tip, 0.31mm
    diameter solder and a binocular microscope - I resoldered about 250 0.5mm
    lead pitch TQFP144s this way (our contract manufacturer was unable to
    operate a fully automated IR reflow oven....morons)

    The most important thing is to be able to visually inspect your soldering
    with a good microscope. forget those stupid "magnifying" lights. A loupe can
    work, but is a real pain in the arse.

    I love my binocular microscope :)

    Cheers
    Terry
     
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