| 摘要 |
PROBLEM TO BE SOLVED: To provide a bump formation method which forms a high bump on an aluminum electrode of a chip, without reducing junctional strength of the chip after soldering. SOLUTION: A copper bump 4 is formed by wire bonding on an aluminum electrode 2 of a chip 1, and a distal end of the copper bump 4 is pressed to have a flat surface. A gold bump 7 is formed by wire bonding on the flat surface. When the bump comprising the copper bump 4 and the gold bump 7 is soldered to an electrode 12 of a substrate 11, the content of solder 13 such as tin which diffuses in the gold bump 7 is blocked by the copper 4 and it does not reach the aluminum electrode 2. Accordingly, formation of alloy layer of aluminum and tin which may deteriorate the junctional strength is avoided. Further, as the solder 13 is prevented by an oxide film on the surface of the copper bump 4 and it does not reach the electrode 2, corrosion due to the solder 13 does not occur in the aluminum electrode 2. |
