This part is a kind of semiconductor called BF421.

Function of this product has High Voltage Transistors(PNP).

Manufacturers : Motorola Inc

Image and pinout :

Some of the text within the PDF file :

MOTOROLA SEMICONDUCTOR TECHNICAL DATA Order this document by BF421/D High Voltage Transistors PNP Silicon COLLECTOR 2 3 BASE 1 EMITTER BF421 BF423 1 2 3 MAXIMUM RATINGS Rating Collector – Emitter Voltage Collector – Base Voltage Emitter – Base Voltage Collector Current Continuous Total Device Dissipation @ TA = 25°C Derate above 25°C Total Device Dissipation @ TC = 25°C Derate above 25°C Operating and Storage Junction Temperature Range Symbol VCEO VCBO VEBO IC PD BF421 –300 –300 –5.0 –500 625 5.0 1.5 12 – 55 to +150 BF423 –250 –250 Unit Vdc Vdc Vdc mAdc mW mW/°C Watts mW/°C °C CASE 29–04, STYLE 14 TO–92 (TO–226AA) PD TJ, Tstg THERMAL CHARACTERISTICS Characteristic Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Case Sym [ ... ]

BF421 PDF Datasheet Download