Manufacturing method of circuit board

A manufacturing method of a circuit board, the method comprising:

• providing a first substrate, a second substrate, and a third substrate, wherein the third substrate has an opening and comprises a first dielectric layer, a second dielectric layer, and a third dielectric layer, the opening penetrates the first dielectric layer and the second dielectric layer, and the opening is fully filled with the third dielectric layer;
• press-fitting the first substrate, the second substrate, and the third substrate so that the second substrate is located between the first substrate and the third substrate;
• forming a plurality of conductive structures so that the first substrate, the second substrate, and the third substrate are electrically connected through the conductive structures to define a ground path;
• and
• forming a conductive via structure to penetrate the first substrate, the second substrate, and the third dielectric layer of the third substrate, wherein the conductive via structure is electrically connected to the first substrate and the third substrate to define a signal path, and the ground path surrounds the signal path.