Manufacturing method for multi-layer circuit board having cavity

A manufacturing method of a multi-layer circuit board having a cavity, comprising:

• providing a core board and forming a through hole that penetrates the core board, wherein the core board comprises a first dielectric layer and two first conductive layers that are disposed on two opposite surfaces of the first dielectric layer and conducted with each other;
• forming two build-up structures, the step of forming each of the two build-up structures comprises:
• providing at least one second conductive layer;
• bonding at least one second dielectric layer to the at least one second conductive layer, and bonding a third conductive layer to the at least one second dielectric layer;
• and
• patterning the third conductive layer to form a stopper layer that exposes a portion of the at least one second dielectric layer, wherein the at least one second conductive layer, the at least one second dielectric layer, and the stopper layer constitute each of the two build-up structures;
• bonding the two build-up structures to two opposite sides of the core board and each of the two build-up structures facing the core board with the stopper layer to form the multi-layer circuit board, the two build-up structures cover the through hole and the stopper layer corresponding to the through hole, wherein each of the two build-up structures comprises the stopper layer, the at least one second dielectric layer and the at least one second conductive layer which are stacked in sequence on the stopper layer;
• and
• removing a portion of one of the two build-up structures corresponding to the through hole, such that the through hole communicates with the removed portion of the one of the two build-up structures outside, to form the cavity.