Printed Wiring Board Contact Model

Evolver Pad Model

This Evolver file models the shape of liquid solder that has wet a printed wiring board (PWB) contact and was used to approximate the amount of solder deposited on the contact pad. Using the command "list_vertex" the user can get a height profile down the centerline of the solder surface. This model profile can then be compared to experimental measurements and the solder volume can be estimated.

The important model parameters are the contact angle the solder makes with the contact pad and the pad dimensions (pad length and pad width) that define the wettable area. The printed paste width and height define the volume of paste on the contact prior to reflow. The amount of flux lost to evaporation during reflow is a measure of how much solder volume remains behind to wet the pad.

Contact angle in degrees:
Pad length in mils:
Pad width in mils ( 8 - 12 mils usually):
Printed paste width (mils):
Printed paste height (mils):
Paste offset from front of pad (mils):
Printed paste length (mils) :
Fraction of solder paste remaining after flux evaporation: