Circuit board, method for manufacturing the same, and semiconductor device

1. A circuit board that includes a base material and a flat-plate electrode formed on at least one main surface of the base material, comprising:

an easy peeling portion formed in at least one of an inner portion and a side portion of the flat-plate electrode, wherein

the easy peeling portion is embedded in the flat-plate electrode,

the flat-plate electrode other than the easy peeling portion is composed of a single unitary metal or alloy composition from a portion of the electrode that adheres to the base material to a portion of the flat-plate electrode that is opposite to the base material, and

an adhesive strength between the flat-plate electrode and the easy peeling portion is less than an adhesive strength between the flat-plate electrode and the base material;

wherein the easy peeling portion is multilayered and in a cross section cut in the direction perpendicular to the base material, in adjacent layers, portions forming the easy peeling portion are arranged alternately with portions not forming the easy peeling portion.

2. The circuit board according to claim 1 , wherein the easy peeling portion is composed of a metal.

3. The circuit board according to claim 1 , further comprising a plurality of flat-plate electrodes, wherein a plurality of the easy peeling portions are formed per flat-plate electrode.

4. The circuit board according to claim 3 , wherein the plurality of easy peeling portions are multilayered per flat-plate electrode in a direction perpendicular to the base material.

5. The circuit board according to claim 4 , wherein in each of the multiple layers, a plurality of the easy peeling portions are formed in a direction parallel to the base material.

6. The circuit board according to claim 1 , wherein the circuit board is one selected from the group consisting of a printed wiring board, a build-up printed circuit board, a flexible printed circuit and a semiconductor package substrate.

7. The circuit board according to claim 1 , wherein

the flat-plate electrode is composed of a metallic material that includes copper, and

the easy peeling portion is composed of a metallic material that includes at least one type of metal selected from the group consisting of chromium, nickel, cobalt, silver, gold, iron and aluminum, or an oxide thereof.

8. The circuit board according to claim 1 , further comprising a plurality of flat-plate electrodes, wherein the flat-plate electrodes are arranged in an area array.

9. A semiconductor device that includes a circuit board and a semiconductor element provided with an electrode, wherein

the circuit board is the circuit board claimed in claim 1 , and

the flat-plate electrode of the circuit board is electrically connected to the electrode of the semiconductor element via a bonding material.

10. The semiconductor device according to claim 9 , wherein an adhesive strength between the easy peeling portion formed in the electrode of the circuit board and the electrode of the circuit board is less than an adhesive strength between the bonding material and the flat-plate electrode of the circuit board.

11. The semiconductor device according to claim 9 , wherein the circuit board includes a plurality of the easy peeling portions, and at least one of the easy peeling portions peels off from the flat-plate electrode of the circuit board.

12. The semiconductor device according to claim 9 , wherein the circuit board includes a plurality of flat-plate electrodes, and a height of at least one of the flat-plate electrodes is greater than an initial height of the flat-plate electrode.

13. The semiconductor device according to claim 9 , wherein the circuit board includes a plurality of flat-plate electrodes and a plurality of the easy peeling portions, at least one of the easy peeling portions peels off from the flat-plate electrodes, and a height of the plurality of flat-plate electrodes above the main surface of the base material is not uniform.

14. The semiconductor device according to claim 9 , wherein the bonding material is solder.