This part is a kind of semiconductor called BC639.

Function of this product has High Current Transistors.

Manufacturers : Motorola Inc

Image and pinout :

Some of the text within the PDF file :

MOTOROLA SEMICONDUCTOR TECHNICAL DATA Order this document by BC635/D High Current Transistors NPN Silicon COLLECTOR 2 3 BASE 1 EMITTER BC635 BC637 BC639 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 PD TJ, Tstg BC 635 45 45 BC 637 60 60 5.0 0.5 625 5.0 1.5 12 – 55 to +150 BC 639 80 80 Unit Vdc Vdc Vdc Adc mW mW/°C Watt mW/°C °C 1 2 3 CASE 29–04, STYLE 14 TO–92 (TO–226AA) THERMAL CHARACTERISTICS Characteristic Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Case Symbol R [ ... ]

BC639 PDF Datasheet Download