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Soldering TQFSOPNCD packages ;-)

Discussion in 'Electronic Design' started by Rich Grise, Feb 10, 2005.

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  1. Rich Grise

    Rich Grise Guest

  2. DaveC

    DaveC Guest

  3. I read in sci.electronics.design that Rich Grise <>
    No, you need a bit big enough to go over the package and solder all the
    lead-outs at once.
     
  4. And curled traces, like the one from C5 to L1. Most of
    the others are 45/45 degrees.
     
  5. Boris Mohar

    Boris Mohar Guest

    Trivial with:

    http://www.metcal.com/products/1.2.2.1.1.htm

    The trick is in applying plenty of flux using a flux pen and drag soldering.
    My daughter has gotten so good that it looks like it was done with a
    machine. Of course you need a10x- 30x stereo microscope with zoom.

    Now tell me how to hand solder this:
    http://focus.ti.com/lit/ml/mxbg003a/mxbg003a.pdf
    Dimensions are in mm.

    Link to TI packaging info http://focus.ti.com/general/docs/packaging.jsp
     
  6. I read in sci.electronics.design that Boris Mohar <borism_-void-
    You also need a daughter.
     
  7. A pair of 4 dioptries glasses are suffiecient

    Rene
     
  8. Boris Mohar

    Boris Mohar Guest

    Of course. A well paid daughter.
     
  9. Leon Heller

    Leon Heller Guest

    Perhaps he's drag soldering, a large tip works better for that than a small
    one. It does look too big even for that, though.

    Leon
     
  10. Guest

    I think he's heating the lead close to the package and applying the
    solder down at the PCB land. Eventually the lead gets hot enough to
    melt the solder and it wets the land. You don't need a particularly
    fine iron to do this. In fact the shape he's hand-carved in that tip is
    much the same shape I prefer: very pointy, steep angle on the tip. Long
    thin tips don't transfer heat well enough.
     
  11. John Larkin

    John Larkin Guest


    or trolling.

    John
     
  12. Rob Gaddi

    Rob Gaddi Guest

    Heat gun and prayer.

    Speaking of which, has anyone found a good way of dealing with those
    thermally enhanced packages where they sink the lead frame to a pad
    underneath the chip? I'm using the aforementioned heat gun + prayer
    technique, combined with preheating the board until the solder paste is
    just starting to melt, then throwing the chip on, but I'm still getting
    a somewhat unacceptable casualty rate.
     
  13. Boris Mohar

    Boris Mohar Guest

    For hand assembled boards I extend the thermal pad outside of the boundaries
    of the chip where it can be accessed by soldering iron or by placing a some
    thermal vias and a copper pad on the opposite side. You can now hand solder
    the pad and solder will go fill up vias and melt the solder paste on the
    other side.

    See http://focus.ti.com/lit/an/slma002/slma002.pdf

    also http://www.ti.com/sc/docs/package/related.htm



    Regards,

    Boris Mohar

    Got Knock? - see:
    Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca
     
  14. Rich Grise

    Rich Grise Guest

    Yikes! Actually, it was supposed to be a joke. I wouldn't try to solder
    anything that small in the first place, and I certainly wouldn't use that
    iron!

    I have a RS "princess" or something that I'd use for smaller work anyway.
    :)

    Thanks!
    Rich
     
  15. Maybe, depending on your vision.
     
  16. Paul Burke

    Paul Burke Guest

    By hand I assume..

    Put a PTH in the underside pad, make it just big enough to get a fine
    iron tip through. Solder the outside pins as normal (tag down the
    corners, little bit of solder on tip, draw across pins- finicky with
    little short pins but works) then flood the underside from underneath.

    Paul Burke
     
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