Diode

A diode, comprising:

• at least one diode element which has a plurality of N-type regions and a plurality of P-type regions, the N-type regions and the P-type regions being alternately arranged in series to form PN junctions;
• and
• an insulated substrate which has electric insulation and includes quartz glass, sapphire, or alumina ceramics, wherein
• the N-type regions and the P-type regions are formed on the insulated substrate
• the N-type regions and the P-type regions are formed in polycrystalline silicon carbide or single-crystal silicon carbide,
• a Zener voltage of a unit diode including a set of the N-type region and the P-type region is between 20 V and 28 V,
• the diode is connected to a secondary side of an ignition coil installed in an internal-combustion engine, and is a constant voltage diode which functions so as to prevent applying a discharge voltage exceeding the Zener voltage to a spark plug,
• the discharge voltage applied to the spark plug is 32 to 38 kV in a range of operating temperature between −30° C. and 120° C.,
• the at least one diode element comprises a plurality of diode elements,
• the diode further comprises:
• a lead frame in which the diode elements are mounted via the insulated substrate;
• a positive terminal which is electrically connected to one end of a first diode element of the diode elements;
• and
• a negative terminal which is electrically connected to one end of a second diode element of the diode elements,
• the other end of the first diode element and the other end of the second diode element are connected via the lead frame, and
• the first diode element is mounted on a front surface of the lead frame, and the second diode element is mounted on a rear surface of the lead frame.