This part is a kind of semiconductor called 31DQ04.

Function of this product has SBD.

Manufacturers : Nihon Inter Electronics

Image and pinout :

Some of the text within the PDF file :

3A Avg. 40 Volts SBD 31DQ04 INSTANTANEOUS FORWARD CURRENT (A) 20 10 5 2 1 0.5 0.2 0 FORWARD CURRENT VS. VOLTAGE 31DQ04 0° 180° θ CONDUCTION ANGLE 3.0 AVERAGE FORWARD POWER DISSIPATION (W) 2.5 2.0 Tj=25°C Tj=150°C 1.5 1.0 0.5 0.2 0.4 0.6 0.8 1.0 INSTANTANEOUS FORWARD VOLTAGE (V) 1.2 0 0 AVERAGE FORWARD POWER DISSIPATION RECT 60° RECT 180° HALF SINE WAVE RECT 120° 31DQ04 D.C. 1234 AVERAGE FORWARD CURRENT (A) 5 PEAK REVERSE CURRENT (mA) PEAK REVERSE CURRENT VS. PEAK REVERSE VOLTAGE Tj= 150 °C 31DQ04 100 50 20 0 10 20 30 PEAK REVERSE VOLTAGE (V) 40 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 AVERAGE REVERSE POWER DISSIPATION 31DQ04 D.C. RECT 300° RECT 240° RECT 180° HALF SINE WAVE 10 20 30 REVERSE VOLTAGE (V) 40 AVERAGE FORWARD CURRENT (A) 0° 180 [ ... ]

31DQ04 PDF Datasheet Download