Method of manufacturing multi-layer circuit board, and multi-layer circuit board

1. A multi-layer circuit board having a connector portion of an inner layer substrate being exposed, the multi-layer circuit board comprising:

an inner layer substrate in which an inner layer circuit is formed, the inner layer circuit including the connector portion; and

an outer layer substrate having an outer layer circuit formed on an insulating layer and having a region corresponding to the connector portion peeled off,

an inner layer circuit side of the inner layer substrate and an insulating layer side of the outer layer substrate being adhered to one another via an adhesive layer so as to face one another, and a conductor layer other than the connector portion of the inner layer circuit being adhered to the outer layer substrate directly by the adhesive layer.

2. A method of manufacturing a multi-layer circuit board having a part of an inner layer circuit being exposed, the method comprising:

forming one or more first slit portions in an outer layer substrate so as to conform with an outer periphery of a region corresponding to a circuit exposure portion of an inner layer substrate, the outer layer substrate having a conductor layer formed on one surface of the outer layer substrate and an adhesive layer covered by an exfoliating paper formed on the other surface of the outer layer substrate, the inner layer substrate having at least a part of the inner layer circuit being exposed, and the one or more first slit portions each penetrating the outer layer substrate while not attaining a closed circuit state;

forming a half cut portion, linked to the one or more first slit portions, in the exfoliating paper of the outer layer substrate, and peeling off and thereby removing the exfoliating paper other than a residual exfoliating paper such that the exfoliating paper in the region corresponding to the circuit exposure portion remains;

stacking and curing the inner layer substrate and the outer layer substrate such that an inner layer circuit side of the inner layer substrate and an adhesive layer side of the outer layer substrate face one another and the residual exfoliating paper is positioned on the circuit exposure portion;

forming an outer layer circuit in the outer layer substrate;

forming one or more second slit portions in the outer layer substrate, the one or more second slit portions being linked to the one or more first slit portions; and

peeling off a region surrounded by the first and second slit portions of the outer layer substrate as a whole with the residual exfoliating paper to thereby expose the circuit exposure portion.

3. The method of manufacturing a multi-layer circuit board according to claim 2 , wherein

the residual exfoliating paper has an area larger than that of the circuit exposure portion.

4. The method of manufacturing a multi-layer circuit board according to claim 3 , wherein

the one or more second slit portions are formed so as to encompass the half cut portion.

5. The method of manufacturing a multi-layer circuit board according to claim 2 , wherein

the one or more second slit portions are formed so as to encompass the half cut portion.

6. A method of manufacturing a multi-layer circuit board having a part of an inner layer circuit being exposed, the method comprising:

applying a mask material to an adhesive layer of an outer layer substrate so as to correspond to a circuit exposure portion of an inner layer substrate, the outer layer substrate having a conductor layer formed on one surface of the outer layer substrate and the adhesive layer formed on the other surface of the outer layer substrate, the inner layer substrate having at least a part of the inner layer circuit being exposed, and the mask material having a size covering the circuit exposure portion;

forming one or more first slit portions in the outer layer substrate so as to conform to a shape of the mask material, the one or more first slit portions each penetrating the outer layer substrate while not attaining a closed circuit state;

stacking and curing the inner layer substrate and the outer layer substrate such that an inner layer circuit side of the inner layer substrate and an adhesive layer side of the outer layer substrate face one another and the mask material is positioned on the circuit exposure portion;

forming an outer layer circuit in the outer layer substrate;

forming one or more second slit portions in the outer layer substrate, the one or more second slit portions being linked to the one or more first slit portions; and

peeling off a region surrounded by the first and second slit portions of the outer layer substrate as a whole with the mask material to thereby expose the circuit exposure portion.