Perforated substrate and method of manufacture

A method of producing a perforated and substantially planar substrate, comprising the steps of;

• a) providing an unperforated substrate having continuous and coplanar first and second major surfaces;
• b) providing a first array of punches adjacent said first major surface,
• c) providing a second array of punches adjacent said second major surface,
• d) providing a first array of female dies adjacent said first major surface, said first array of female dies being aligned with said second array of punches,
• e) providing a second array of female dies adjacent said second major surface, said second array of female dies being aligned with said first array of punches,
• f) punching out a first set of blanks by moving said first array of punches entirely thru said substrate and into said second array of female dies, said blanks exiting thru said second array of female dies, and
• g) punching out a second set of blanks by moving said second array of punches entirely thru said substrate and into said first array of female dies, said second set of blanks exiting thru said first array of female dies, individual punches of said first array of punches being arranged in an alternating and laterally spaced fashion relative to individual punches of said second array of punches such that equal and opposite stress forces are introduced into the substrate that essentially cancel each other thus maintaining the planar characteristic of the substrate.