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Soldering QFN surface mount devices

Discussion in 'Electronic Components' started by Daniel Kelly \(AKA Jack\), Jun 17, 2004.

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  1. Hi,

    I need to solder a 3 x 3 (total 9 pin) QFN surface mount device. But I
    don't have any of the exotic soldering kit needed for this job. Has anyone
    attempted soldering these packages without re-flow kit?

    I have two ideas of how this may be possible

    1) Manually solder thin wires onto the QFN, one by one. Then connect these
    wires to my PCB. The end result will be a "belly-up" QFN package with
    little spider-like wire legs connecting it to the PCB.

    2) Solder the QFN directly onto my PCB by taking advantage of the tiny leg
    that sticks out the side of the chip.

    I think technique 1 has a much great chance of success than technique 2.

    The chip is just a Lithium Polymer charger chip (from Maxim). It doesn't
    use large currents or high frequencies (all the charge current is dealt with
    by an external MOSFET).

    All sharing of experience is very very much appreciated.

    Many thanks,

    Sorry for the cross-posting.
  2. Dear Colin,

    Thanks again for your excellent advice... the PDF is very handy.


  3. Leon Heller

    Leon Heller Guest

    I've managed to solder the ADI ADXL202 which has a similar package onto a
    home-made PCB without too many problems. I tinned the pads, used plenty of
    flux and held a fine soldering iron tip against the junction between each
    contact and the pad. Inspect each joint carefully with a powerful magnifier.

  4. Using soldering paste you will have no issue with option 2. Just put some
    paste on each pad, position the chip, and then heat each pad one by one
    using a standard (but fine pitch) iron until refusion of the paste. Of
    course an hot air iron will be far easier...

  5. Antti Lukats

    Antti Lukats Guest

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