This part is a kind of semiconductor called 40HF120.

Function of this product has Standard Recovery Diodes.

Manufacturers : Vishay Siliconix

Image and pinout :

Some of the text within the PDF file :

40HF(R) Series Vishay High Power Products Standard Recovery Diodes, (Stud Version), 40 A FEATURES • • • • High surge current capability Stud cathode and stud anode version Leaded version available Types up to 1600 V VRRM RoHS COMPLIANT • RoHS compliant • Designed and qualified for multiple level TYPICAL APPLICATIONS DO-203AB (DO-5) PRODUCT SUMMARY IF(AV) 40 A • • • • • Battery charges Converters Power supplies Machine tool controls Welding MAJOR RATINGS AND CHARACTERISTICS PARAMETER TEST CONDITIONS 40HF(R) 10 TO 120 40 IF(AV) IF(RMS) IFSM I2 t VRRM TJ 50 Hz 60 Hz 50 Hz 60 Hz Range 100 to 1200 - 65 to 190 TC 140 62 570 595 1600 1450 1400/1600 - 65 to 160 140/160 40 110 UNITS A °C A A A2s V °C ELECTRICAL SPECIFICATIONS VOLTAGE RATINGS TYP [ ... ]

40HF120 PDF Datasheet Download