Method for manufacturing printed circuit board

A method for manufacturing a printed circuit board, comprising:

• providing a core substrate comprising a first dielectric layer, the core substrate having an inner region and a trace region surrounding and connected with the inner region, the first dielectric layer having a first surface and a second surface opposite to the first surface;
• forming a first trace layer and a peelable metal layer on the first surface and forming a second trace layer on the second surface in the trace region, the peelable metal layer being in the inner region, the peelable metal layer having a smooth surface furthest away from the first surface;
• forming a photoresist layer on the smooth surface;
• roughening surfaces of the first trace layer, surfaces of the second trace layer, and surfaces of the peelable metal layer uncovered by the photoresist layer;
• removing the photoresist layer from the smooth surface;
• laminating a second dielectric layer on the first trace layer and the peelable metal layer and laminating a third dielectric layer on the second trace layer;
• forming a third trace layer on a surface of the second dielectric layer furthest away from the first dielectric layer and forming a fourth trace layer on a surface of the third dielectric layer furthest away from the first dielectric layer;
• roughening surfaces of the third trace layer and surfaces of the fourth trace layer;
• laminating a fourth dielectric layer on the third trace layer and the second dielectric layer, and laminating a fifth dielectric layer on the fourth trace layer and the third dielectric layer;
• forming a top trace layer on a surface of the fourth dielectric layer furthest away from the second dielectric layer, and forming a bottom trace layer on a surface of the fifth dielectric layer furthest away from the third dielectric layer corresponding to the trace region;
• and
• along a boundary between the inner region and the trace region, defining a slit running through from the fifth dielectric layer to the second dielectric layer;
• separating the peelable metal layer from the second dielectric layer and removing the peelable metal layer, the first dielectric layer, the third dielectric layer and the fifth dielectric layer surrounded by the slit to form a cavity, the second dielectric layer exposed in the cavity.