PLASMA ION-IMPLANTATION (PII) TO IMPROVE THE WEAR LIFE OF TUNGSTEN CARBIDE DRILL BITS USED IN PRINTED WIRING BOARD (PWB) FABRICATION

Plasma ion implantation (PII) is a process that allows for cost-effective implantation of large-scale (or large numbers of small-scale) three-dimensional objects. In PII an object to be implanted is immersed in a plasma comprised of the ions to be implanted (such as nitrogen). The object is then pulse biased to a very high (50-100 kV) negative potential, using a repetitive train (100-1000 Hz) of short-duration (10-30 mus) voltage pulses to achieve omnidirectional and simultaneous implantation of ions over its entire surface. This paper describes the use of PII to extend the wear life of tungsten carbide drill bits used in multilayer printed wiring board (PWB) fabrication. A twofold to threefold wear life improvement was achieved with nitrogen ions implanted at 95 kV using the PII facility at Hughes Research Laboratories. The PII process was compared with three conventional processes known to improve PWB drill bit wear life: conventional nitrogen ion beam implantation, ion beam mixing of TiN and CrN, and physical vapor deposition of TiN. Comparable wear life results from all four techniques.