Indium Blog

Ball Attach Surface Finishes

  • Ball Attach
  • Flux
  • Indium Corporation
  • Pb-Free
  • Pb-Free Solder
  • Solder
  • Solder Flux
  • Soldering
  • Solder Spheres
  • Solderability

  • Just incase you were wondering, here are the wetting results you can expect when soldering Pb-free spheres to different surface finishes. The chart shown here is the average result of about 15 different ball attach fluxes from across the industry. This was just some left-over data from testing that will appear in the October issue of Advanced Packaging.

    The x and y axis are not labeled due to space constraints, but x is obviously surface finish. The y axis is (less obviously) the increase in solder diameter after reflow. Here’s the formula:

    Sø = (Ds/Di)100-100

    Where: Sø = Increase in sphere diameter,
    Ds = Diameter of post-reflow solder, and
    Di = Initial diameter of sphere

    Authored by previous Indium Application Manager Jim Hisert