Semiconductor device, mounting construction of a semiconductor device, and method of manufacturing the semiconductor device with the mounting construction
A semiconductor pellet is mounted on a circuit board. The pellet has a first terminal pad and a first solder layer formed on the first terminal pad. The circuit board has a second terminal pad and a second solder layer formed on the second terminal pad. A metal ball is positioned between the first and the second solder layers such that when the solder layers are reflowed, an intermetallic compound is formed between the metal ball and the first terminal pad and between the ball and the second terminal pad, the intermetallic compound including a thickness not more than 10 μm in areas in which said metal ball is closest to the second terminal pad and to the first terminal. The metal ball has a surface neither in contact with the first solder layer nor the second solder layer.
1 . A semiconductor device, comprising:
a base;
a first terminal pad formed on the base;
a first solder layer formed on the first terminal pad; and
a metal ball mounted to the first terminal pad by the first solder layer, the metal ball has a first surface covered with the first solder layer;
wherein a distance between the metal ball and the first terminal pad is less than or equal to 10 μm in a first area in which the metal ball is closest to said first terminal pad.
2 . The semiconductor device according to claim 1 , wherein an intermetallic compound is formed in the first area.
3 . The semiconductor device according to claim 2 , wherein the metal ball, the first solder layer, and the first terminal pad react with one another to form the intermetallic compound.
4 . The semiconductor device according to claim 3 , wherein the first solder layer is an Sn—Ag—Cu solder, and the first terminal pad and the metal ball are formed of copper, wherein the intermetallic compound is Cu 6 Sn 5 .
5 . The semiconductor device according to claim 3 , wherein said metal ball is formed of nickel (Ni).
6 . The semiconductor device according to claim 3 , wherein said metal ball is formed of tungsten (W).
7 . The semiconductor device according to claim 1 , wherein said metal ball ( 21 ) has a degree of purity higher than 99.99%.
8 . A mounting structure for a semiconductor device, comprising:
a base having a first terminal pad;
a circuit board having a second terminal pad;
a first solder layer formed on the first terminal pad;
a second solder layer formed on the second terminal pad; and
a metal ball positioned between the base and the circuit board, the metal ball mounted to the first terminal pad by the first solder layer and to the second terminal pad by the second solder layer, the metal ball has a first surface covered with the first solder layer, a second surface covered with the second solder layer and a third surface exposes a surface of the metal ball;
wherein a distance between the metal ball and the first terminal pad is less than or equal to 10 μm in a first area in which the metal ball is closest to the first terminal pad, and a distance between the metal ball and the second terminal pad is less than or equal to 10 μm in a second area in which the metal ball is closest to the second terminal pad.
9 . The semiconductor device according to claim 8 , wherein the metal ball, the first solder layer, and the first terminal pad react with one another to form an intermetallic compound, wherein the metal ball, the second solder layer, and the second terminal pad react with one another to form an intermetallic compound.
10 . The semiconductor device according to claim 9 , wherein the intermetallic compound fills in the first area and in the second area.
11 . The semiconductor device according to claim 10 , wherein said second solder layer is an Sn—Ag—Cu solder, and said second terminal pad and said metal ball are formed of Cu, wherein the intermetallic compound is Cu 6 Sn 5 .