Contact terminals 792 are arrayed on a distal end of printed circuit board 790 on an extension shown with brackets in FIG. 4F. As further shown in FIG. 4F, substrate tiles 310 are held in X and Y position, for example and without limitation, with respect to adjacent ones of substrate tiles 310 so that probe tips 322 are held in X and Y registration in a test plane, and substrate tiles 310 are alig