This part is a kind of semiconductor called 2SD2641.

Function of this product has Silicon NPN Triple Diffused Planar Transistor.

Manufacturers : Sanken Electric

Image and pinout :

Some of the text within the PDF file :

2SD2641Darlington Equivalent circuit B C (70Ω) E Silicon NPN Triple Diffused Planar Transistor (Complement to type 2SB1685) Application : Audio, Series Regulator and General Purpose sAbsolute maximum ratings (Ta=25°C) sElectrical Characteristics (Ta=25°C) Symbol Ratings Unit Symbol Conditions Ratings Unit VCBO 110 V ICBO VCB=110V 100max µA VCEO 110 V IEBO VEB=5V 100max µA VEBO 5 V V(BR)CEO IC=30mA 110min V IC 6 A hFE VCE=4V, IC=5A 5000min∗ IB 1 A VCE(sat) IC=5A, IB=5mA 2.5max V PC 60(Tc=25°C) W VBE(sat) IC=5A, IB=5mA 3.0max V Tj 150 °C fT VCE=12V, IE=–2A 60typ MHz Tstg –55 to +150 °C COB VCB=10V, f=1MHz 55typ pF ∗hFE Rank O(5000 to 12000), P(6500 to 20000), Y(15000 to 30000) sTypical Switching Characteristics (Com [ ... ]

2SD2641 PDF Datasheet Download