This part is a kind of semiconductor called 1N6642US.

Function of this product has SWITCHING / SIGNAL DIODES.

Manufacturers : SENSITRON SEMICONDUCTOR

Image and pinout :

Some of the text within the PDF file :

SENSITRON ___ SEMICONDUCTOR 1N6638/US thru 1N6642/US StandaSrWd ITCHING / SIGNAL DIODES ______________________________________________________________________________________ TECHNICAL DATA DATA SHEET 4081, REV E AVAILABLE AS 1N, JAN, JANTX, JANTXV JANS JAN EQUIVALENT* SJ*, SX*, SV*, SS* Switching / Signal Diodes Qualified per MIL-PRF-19500/578, /609 DESCRIPTION: This metallurgically bonded switching/signal diode series is military qualified per MIL-PRF19500/578, /609 and is targeted for space, commercial and military aircraft, military vehicles, shipboard markets and all high reliability applications. FEATURES / BENEFITS:  Ultra fast recovery time  Metallurgically bonded  Small size, high density  Very low capacitance  Hot solder dipped  JANS available per MI [ ... ]

1N6642US PDF Datasheet Download