Cathode Lifetime Issues in Field Emission Displays
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- 10000 hr (Monochrome LV FED package) > 10000 hr (Monochrome LV FED package) > 5000 hr (LV FED Package) - 5000 hr (Actively pumped HV FED system) > 3000 hr (Color HV FED package) > 70000 hr (actively pumped, discrete FEAs) > 25000 hr (actively pumped mono chrome FEDs)
Table 1 Reported display lifetimes from several FED developmental organizations
49 Mat. Res. Soc. Symp. Proc. Vol. 558 0 2000 Materials Research Society
To aid in the discussion of failure mechanisms, it is useful to look at the FED manufacturing process. Figure 1 presents a typical process flow diagram for the fabrication of field emission displays. The principal components of the display are the cathode glass plate, phosphor anode plate, spacer elements to maintain the spatial uniformity, vacuum package assembly and the drive electronics. While each constituent component can be tested and inspected (and defective parts discarded as yield loss), latent defects are expected to occur. Subsequent failure during operation can be identified as a reliability issue. A similar situation exists for the display assembly operation also. If early detection is possible, improperly assembled parts can be counted as yield loss. Otherwise, they may contribute to either early life failures, or present long term reliability issues. From a reliability perspective, a low voltage FED design is preferred. A display that operates at < 500V requires much less of the component assembly and functional capabilities than does one operating at voltages greater than 3000V.
Vacuum Packaging Process Anode fabrication Cathode Fabrication
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Process flow diagram for the integration of FEDs
FAILURE MODES Various issues associated with FED reliability can be broadly classified as: defectivity failures caused by process induced defects, module level failures caused by the failure of individual components like driver electronics, high voltage power modules, external interconnects, etc., component level catastrophic destruction caused by particulate contamination and charge build up on dielectrics, emission current instabilities, and degradation due to poor vacuum conditions in the package. We outline various failure modes is Figure 2. This is followed by a detailed discussion of the various factors affecting display life. We focus on emitter instabilities which are relatively unique to field emission devices compared to other FPD technologies.
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IDISPLAY FAILURE MODES *Defectivity Fai
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Display reliability - Major display failure modes
Defectivity Failures While defectivity failures may occur during the operational life of the display, they actually stem from component level manufacturing and assembly operations. These are inherent defects that can only be detected by operating the device. The primary concern
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