A wiring structure includes an upper conductive structure, a lower conductive structure and an intermediate layer. The upper conductive structure includes at least one upper dielectric layer and at least one upper circuit layer in contact with the dielectric layer. The lower conductive structure includes at least one lower dielectric layer and at least one lower circuit layer in contact with the lower dielectric layer. The at least one lower dielectric layer of the lower conductive structure is substantially free of glass fiber. The intermediate layer is disposed between the upper conductive structure and the lower conductive structure and bonds the upper conductive structure and the lower conductive structure together. The upper conductive structure is electrically connected to the lower conductive structure.