This part is a kind of semiconductor called 2SK1020.
Function of this product has N-Channel MOSFET Transistor.
Manufacturers : Inchange Semiconductor
Image and pinout :

Some of the text within the PDF file :
INCHANGE Semiconductor isc N-Channel MOSFET Transistor DESCRIPTION ·Drain Current –ID=30A@ TC=25℃ ·Drain Source Voltage- : VDSS=500V(Min) APPLICATIONS ·high voltage, high speed power switching isc Product Specification 2SK1020 ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL ARAMETER VALUE UNIT VDSS VGS ID Ptot Tj Tstg Drain-Source Voltage (VGS=0) 500 V Gate-Source Voltage ±30 V Drain Current-continuous@ TC=25℃ 30 A Total Dissipation@TC=25℃ 300 W Max. Operating Junction Temperature 150 ℃ Storage Temperature Range -55~150 ℃ THERMAL CHARACTERISTICS SYMBOL PARAMETER MAX UNIT Rth j-c Rth j-a Thermal Resistance,Junction to Case 0.416 ℃/W Thermal Resistance,Junction to Ambient ℃/W isc website:www.iscsemi.cn 1 isc & iscsemi is registered trademark PDF p [ ... ]
2SK1020 PDF Datasheet Download
