FIGS. 5A, 5B, and 5C show the results of operations 201, 203 and 205 respectively, according to another embodiment. In the embodiment of FIGS. 5A, 5B, and 5C, a one vent hole 513 (shown in FIG. 5C) is formed to provide a vent opening for plated openings 503, 505, 507 and 509. Figure A shows workpiece 501 after openings 503, 505, 507 and 509 are formed. FIG. 5B shows openings 503, 505, 507 and 509 after being plated with a sidewall plating (511). In one embodiment, vent hole opening 513 has a center located between the four openings 503, 505, 507 and 509 and has a diameter that removes plated material on the sidewalls of each of openings 503, 505, 507 and 509. In one embodiment where openings 503, 505, 507 and 509 have a diameter of 200 μm and have a center spacing pitch of 0.4 mm, opening 513 has a diameter of 420 μm. However, these values may be different in other embodiments.

In other embodiments, one vent opening may provide a vent path for a different number of plated openings. For example, an opening may provide a vent path for 1, 3, 5, or greater number of plated openings. In the embodiments of FIGS. 3C, 4C, and 5C, the vent openings extend all the way though the workpiece. However, in other embodiments, the vent openings may extend only through a portion of the workpiece.