This part is a kind of semiconductor called STP6A60.

Function of this product has Bi-Directional Triode Thyristor.

Manufacturers : SemiWell Semiconductor

Image and pinout :

Some of the text within the PDF file :

SemiWell Semiconductor Bi-Directional Triode Thyristor Symbol STP6A60 ○ Features ◆ Repetitive Peak Off-State Voltage : 600V ◆ R.M.S On-State Current ( IT(RMS)= 6 A ) ◆ High Commutation dv/dt ◆ Non-isolated Type TO-220 2.T2 ▼ ▲ ○ 3.Gate 1.T1 ○ General Description This device is suitable for AC switching application, phase control application such as fan speed and temperature modulation control, lighting control and static switching relay. 1 2 3 Absolute Maximum Ratings Symbol VDRM IT(RMS) ITSM I2 t PGM PG(AV) IGM VGM TJ TSTG ( TJ = 25°C unless otherwise specified ) Condition Ratings 600 TC = 100 °C One Cycle, 50Hz/60Hz, Peak, Non-Repetitive 6.0 60/66 18 3.0 0.3 2.0 10 - 40 ~ 125 - 40 ~ 150 2.0 Parameter Repetitive Peak Off-State Voltage R. [ ... ]

STP6A60 PDF Datasheet Download