Damage under UCSB bias bonds After plucking bias wire bonds in order to re-bond with higher loop heights, damage is seen on all modules on second sensor At minimum, “dots” seen at the edge of the guard ring and n+ metal directly under wire At maximum, lines of metal deposited in the area between the guard ring and n+ metal directly under wire Beginning of damage seen after a 20 minute ARCS test Guard Ring Guard Ring n+ metal Guard Ring n+ metal

Damage under UCSB channel bonds Under all channel bonds, the passitivation is discolored at guard ring, bias ring, DC pad, and bond pad Channel bond location Channel bond location Guard Ring n+ metal

Damage to Bias Wire Bonds After seeing Al deposited onto the sensor’s surface, we looked at the underside of the bias return wire bonds for damage We found that all 4 bias return wire bonds studied are pocked in same region. This region lies above the n+ metal on the outside of the module We assume that corona is causing ionization of Al which then follows electric field to sensor surface