exploded BTA16 triac

just some closeup pics of a BTA16 600B triac (engraving readable on the thermoplast piece on the left) i accidentally disintegrated by using a too small core on the smoothing choke that was supposed to limit the current into the rectifier and capacitor bank during ramp up. The choke saturated and no longer was a choke, thus placing a large, mostly discharged capacitor bank accross the mains when the triac fired, weakest link was first the triac which initially failed short circuit but then quickly opened again (literally) under the resulting current :) visible here is the white layer between the silicon die and the tinned copper TO220 mounting plate; a ceramic insulator that provides the 2,5kV chassis insulation featured by the BTA triac series.