This part is a kind of semiconductor called BC639.

Function of this product has NPN EPITAXIAL SILICON TRANSISTOR.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

BC635/637/639 BC635/637/639 Switching and Amplifier Applications • Complement to BC636/638/640 NPN Epitaxial Silicon Transistor Absolute Maximum Ratings Ta=25°C unless otherwise noted Symbol Parameter VCER Collector-Emitter Voltage at RBE=1KΩ : BC635 : BC637 : BC639 VCES Collector-Emitter Voltage : BC635 : BC637 : BC639 VCEO Collector-Emitter Voltage : BC635 : BC637 : BC639 VEBO Emitter-Base Voltage IC Collector Current ICP Peak Collector Current IB Base Current PC Collector Power Dissipation TJ Junction Temperature TSTG Storage Temperature • PW=5ms, Duty Cycle=10% Electrical Characteristics Ta=25°C unless otherwise noted Symbol Parameter Test Condition BVCEO Collector-Emitter Breakdown Voltage : BC635 : BC637 : BC639 IC=10mA, IB=0 ICBO IEBO hFE1 hFE2 h [ ... ]

BC639 PDF Datasheet Download