CONTACT POTENTIAL MEASUREMENTS OF HARD-DISK DRIVE SURFACES IN HUMID ENVIRONMENTS

Contact potential difference (CPD) experiments were conducted by the v ibrating probe (Kelvin) method on humidity-exposed hard disk drive sur faces. The measurements were made at various locations along the circu mference of a wear track caused by the sliding contact with a spherica l silicon pin, operated in a pin-on-disk configuration. The load on th e pin, rotational speed of the disk, and the humidity were controlled. The CPD signals varied along the wear track and the magnitude of the CPD change increased with the load from 29 to 98 mN at a fixed relativ e humidity. The CPD signals also increased linearly with relative humi dity ranging from 30% to 70% as the normal load was fixed at 29 and 49 mN. The CPD signal appears to saturate at a load of 98 mN where the r elative humidity is 50% and higher. (C) 1996 American Vacuum Society.