The application provides a circuit board and a manufacturing method thereof. A medium layer source, i.e., a resin source, is divided into multiple parts, i.e., a top medium layer above a buried device and an intermediate medium layer between core boards. In a pressing process, the top medium layer above the buried device fills a gap between an upper frame (a second core board) and the buried device, and the intermediate medium layer between the core boards quickly fills a gap between a lower frame (a first core board) and the buried device. The
vertical distance of resin flow is greatly reduced, the resin flowability is greatly improved, the problem of insufficient filling caused by insufficient resin flowability or mismatched curing speed can be effectively avoided, the problem of insufficient glue filling capacity of a traditional single-frame design when
processing a large-thickness component is solved, and the reliability and stability of the buried device are improved.