Circuit board and manufacturing method thereof

A manufacturing method of a circuit board, comprising:

• providing a composite structure layer, wherein the composite structure layer comprises a first structure layer, a second structure layer, and a connecting structure layer, the connecting structure layer connects the first structure layer and the second structure layer, the first structure layer comprises at least one first conductive member, and the second structure layer comprises at least one second conductive member;
• forming at least one conductive structure to at least penetrate the connecting structure layer and be electrically connected to the at least one first conductive member of the first structure layer and the at least one second conductive member of the second structure layer;
• providing a thermally conductive substrate and a thermal interface material layer, wherein the thermal interface material layer is located between the composite structure layer and the thermally conductive substrate;
• compressing the composite structure layer, the thermal interface material layer, and the thermally conductive substrate so that the second structure layer is connected to the thermally conductive substrate through the thermal interface material layer;
• and forming a cavity to penetrate the first structure layer and the connecting structure layer to expose the at least one second conductive member of the second structure layer, wherein the at least one conductive structure is formed when the composite structure layer is provided, and providing the composite structure layer comprises:
• providing the first structure layer, wherein the first structure layer further comprises an insulating layer, the at least one first conductive member comprises multiple circuit layers, and the multiple circuit layers are disposed in the insulating layer and on two opposite surfaces of the insulating layer;
• providing the at least one second conductive member, wherein the at least one second conductive member is a metal plate, wherein the metal plate has an upper surface and a lower surface opposite to each other, a plurality of first blind holes extending in a direction from the upper surface to the lower surface, and a plurality of second blind holes extending in a direction from the lower surface to the upper surface, and the first blind holes respectively correspond to the second blind holes;
• providing the connecting structure layer between the first structure layer and the metal plate, wherein the at least one conductive structure passes through the connecting structure layer, and the connecting structure layer is in a B-stage state;
• compressing the first structure layer, the connecting structure layer, and the metal plate so that the at least one conductive structure is connected to the multiple circuit layers and the metal plate, and the connecting structure layer changes from the B-stage state to a C-stage state;
• removing a part of the metal plate so that the first blind holes communicate with the second blind holes to define a plurality of openings;
• and filling an insulating resin in the openings, wherein the insulating resin fills the openings, the insulating resin is flush with two surfaces of the metal plate, and the metal plate and the insulating resin define the second structure layer.