We would like to write some Ravel programming to measure solder ball to package edge and I am unable to define ballpad and obtain a relation. Is there somehow to do this?
you can get all the ballpads from the Ravel predefined relation "ballpad".
Please refer Ravel Manual section 4 for all the ravel predefined relations
here is sample code which measures the distance between component and ballpad
(select (ball_pad comp dist) (transform (ball_pad comp) (combine ballpad component) (ball_pad comp (distance (center ball_pad) comp)) ) (dist < (value MIN_SPACING)) )