Thermally conductive board

A thermally conductive board, comprising:

• a metal substrate;
• a metal layer;
• a thermal conductive insulating polymer layer located between the metal layer and the metal substrate;
• and
• a ceramic material layer, wherein the ceramic material layer comprises an upper ceramic layer or a lower ceramic layer, or comprises both the upper ceramic layer and the lower ceramic layer, wherein the upper ceramic layer is disposed between the metal layer and the thermal conductive insulating polymer layer, and the lower ceramic layer is disposed between the thermal conductive insulating polymer layer and the metal substrate;
• wherein the metal layer has a thickness of 0.3-10 mm;
• wherein when only one of the upper ceramic layer and the lower ceramic layer is included in the thermally conductive board, each of the upper ceramic layer and the lower ceramic layer has a thickness of 3-100 μm;
• when both the upper ceramic layer and the lower ceramic layer are included in the thermally conductive board, a total thickness of the upper ceramic layer and the lower ceramic layer is 5-200 μm;
• wherein a ratio of a volume resistivity at 175° C. to a volume resistivity at 25° C. for the thermally conductive board is defined as a retention value, and the retention value is at least 10−4;
• and
• wherein a voltage endurance of the thermally conductive board under HHBT at a temperature of 85° C. and a relative humidity of 85% for a duration of 1000 hours is at least DC1000V.