Tombstone Example tomb-E for the Surface Evolver

[Click for the tomb-E.fe datafile in a second window.]

This model omits the contact facets between the liquid solder and the pad, accounting for the equivalent energy with an edge integral. The interface on the chip remains represented by facets.

Notable features:

• The contact angle on the pad is now implemented by defining an energy line integral for the edge on constraint 9. This eliminates problems due to negative tension facets (at least on the pad). No edge integral is necessary for the volume, since the pad is at z = 0.
• There is an improved evolution script, gogogo. But there are still problems eventually.
• Note how the solder contact line moves all the way up to the top of the chip and stops, due to the one-sided constraint 15.
• Make sure that each contact edge on the chip has enough one-sided constraints on it. For example, edge 15 (crossing the front of the chip) has four one-sided constraints on it, and it needs them all.