| Popis: |
Probe-tip shape and patch-wiring are two principal probe-card factors that affect wafer yields and wafer sort probing consistency. Experimental data show that average yields increase by 20 dice per wafer when standard probe cards are modified. The two-step process consists of eliminating the patch-wiring (11 dice per wafer) and changing from flat-tip to radius-tip probes (9 dice per wafer). The author discusses the advantages of the radius tip probe over the flat-tip probe. It is shown that the radius tip increases yields and reduces system down time. An average of 20 dice per wafer was obtained using the radius-tip probe cards. The consistency of probing also improved. It is also shown that radius tips do not become flat after a few cleanings, as many probe-card manufacturers claim. The reasons for better results with the radius tip are examined. Proper cleaning techniques, which are different from those recommended for flat tips, are described. Critical probe-card parameters and recommended probe-card configurations are shown. > |
