This file sets up a column of liquid solder between two wetting patches of different radius, and calculates the capillary force between them.
The pads are oriented normal to the z-axis, so gravity works (volume can be computed using the standard z*zhat integrand plus a content
integrand around the top trace). Circular pads are used for now, but this can be changed, though it's not easy.
Running this file is a breeze. Just set your parameters, hit the "submit" button, save the generated file as yourname.fe,
and then in the same directory, type
The beauty of Evolver codes is that actual application is limited only
by the user's imagination. We therefore encourage the user to use
this code in whatever way it is helpful. The original driving force
for writing this particular evolver solution was the issue of
self-allignment of flip chip assemblies with underfill/solder bumps
applied at the wafer level. This code, which calculates the capillary
forces associated with the liquid solder joint between two
(potentially misalligned) pads given their relative positions,
addresses the simplified geometry existing without the underfill.
Another code written for the underfill project can be found
This code was written by Adam C. Powell, IV while employed at the
Materials Science and Engineering Laboratory at the National Institute
of Standards, with partial support from the Advanced Techology
Share and enjoy!
Bottom pad radius, mm:
Top pad radius, mm:
Spacing between pads, mm:
Volume = pi r1^2 hgt * this:
X offset of top pad, mm:
Y offset of top pad, mm:
Wetting angle on bottom pad:
Wetting angle on top pad:
Wetting angle on bottom outside pad:
Wetting angle on top outside pad:
Surface tension (kg/s^2):