Method for producing circuit board, for semiconductor package, having cavity for accommodating semiconductor element

A method for producing a circuit board for a semiconductor package, comprising the steps of:

• forming an opening for a cavity for accommodating a semiconductor element at a predetermined portion of a core substrate having metallic layers on both surfaces thereof,
• forming a first plating film on the inner wall of the cavity opening to be connected to a circuit pattern formed on at least one surface of the core substrate, forming a resist film on both the surfaces of the core substrate so that the cavity opening is covered,
• removing a portion of the resist film corresponding to the circuit pattern on the core substrate and a portion thereof corresponding to the cavity opening but having a diameter smaller than that of the cavity opening by an exposure/development process,
• forming a second plating film while using the resist film as a mask, on a portion corresponding to the circuit pattern exposed on the core substrate and the first plating film formed on the inner wall of the cavity opening,
• releasing the resist film from both the surfaces of the core substrate,
• removing a portion of the first plating film exposed on the core substrate and the underlying metallic layer, and
• removing the second plating film covering the portion corresponding to the circuit pattern of the core substrate and the inner wall of the cavity opening.