Circuit board structure

A circuit board structure includes a substrate, a first build-up structure layer, a first external circuit layer, a second external circuit layer, at least one first conductive through hole and a plurality of second conductive through holes. A first build-up structure layer is disposed on the first circuit layer of the substrate. The first external circuit layer is disposed on the first build-up structure. The second external circuit layer is disposed on the second circuit layer and part of the third dielectric layer of the substrate. The first conductive through hole is electrically connected to the first external circuit layer and the second external circuit layer to define a signal path. The second conductive through holes surround the first conductive through hole, and the first external circuit layer, the second conductive through holes, the first circuit layer, the external conductive layer, and the second external circuit layer define a first ground path, and the first ground path surrounds the signal