Connect with us

Sn/Pb plating on heat spreader

Discussion in 'Electronic Basics' started by Dummy, Aug 12, 2004.

Scroll to continue with content
  1. Dummy

    Dummy Guest

    I have two different types of cubical heat spreaders. There is a Sn/Pb
    plating layer on each surface of heat spreader.
    Heat spreader A with 7 micron plating layer thickness.
    Heat spreader B with 0.5 micron plating layer thickness.
    If both heat spreaders have equal heat conductivity characteristic,
    will the one with thinner plating layer be having solderability
    problem?
    If so, how the thickness of Sn/Pb plating layer is related to
    solderability?
    I worry that the thinner plating layer will pose the solderability
    problem and reduce the heat transfer efficiency.
     
  2. Rich Grise

    Rich Grise Guest

    It shouldn't make a noticeable difference. The surface is plated
    with, essentially, solder. When the joint gets to the right temp,
    the solder flows just like with any properly-tinned part. Once
    the added solder wets the joint, the plating thickness becomes
    moot.

    Hope This Helps!
    Rich
     
  3. James Meyer

    James Meyer Guest

    Soldering results from metals dissolving or alloying at the interface.
    If the base material of the spreader is something like aluminum which won't
    dissolve in tin/lead solder, then there could very well be a problem with a thin
    plating thickness. The original poster didn't state what the spreader material
    is and whether there are any other layers of intermediate materials involved.

    Jim
     
  4. Dummy

    Dummy Guest

    For heat spreader A,
    1st layer will be Sn/Pb Plating, with 6-8u thickness.
    2nd layer is Ni layer with 9-10u thickness
    3rd layer Cu layer with 10u thickness
    4th and the last layer will be the substrate, which contains Zn and
    little Al.

    For heat spreader B,
    1st layer will be Sn/Pb Plating, with 0.5u thickness.
    2nd layer is Ni layer with 2-2.5u thickness
    3rd layer Cu layer with 20u thickness
    4th and the last layer will be the substrate, which contains Zn and
    little Al.

    Surface element of the Heat spreader A is Sn/Pb mainly; while for Heat
    spreader B, the main elements are Ni and Cu, with little content of
    Sn.
     
  5. James Meyer

    James Meyer Guest

    Nickel, copper, and zinc are all compatible with ordinary tin/lead
    solder. You can solder to any of them. The plating layers are rather thin
    though. A solder preform or paste along with just enough heat, using hot air or
    an oven, to get the job done would probably work with either spreader.

    Since there are so many variables involved, your answer will probably
    have to be gotten using empirical methods. Try several samples with different
    methods and test the "peel strength" of the resulting joints.

    Jim
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-