1. An ultrasonic motor which produces elliptical vibration by inducing longitudinal vibration and flexural vibration at the same time and drives a driven body by obtaining a drive power from the elliptical vibration, comprising:
a piezoelectric device;
friction contact members which are provided on one face of the piezoelectric device so as to move a driven body by the elliptical vibration of the piezoelectric device;
a holder member which positions and holds the piezoelectric device in a casing and is disposed corresponding to a node of the longitudinal vibration or in the vicinity thereof on the other face of the piezoelectric device and a node of the flexural vibration or in the vicinity thereof, the holder member having an engagement convex portion at the front end portion thereof and being provided with a pair of curved sliding contact projection portions which are projected from two faces perpendicular to the moving direction of the driven body;
a position limiting member which accommodates the piezoelectric device and has accommodation holes each constituted of a sliding contact concave portion for accommodating the sliding contact projection portion of the holder member such that it makes a sliding contact therewith freely and an engagement concave portion for accommodating the engagement convex portion of the sliding contact projection portion, the sliding contact concave portion and the engagement concave portion being provided in each of the inner wall faces in a direction perpendicular to the moving direction of the driven body; and
a pressure member which presses the holder member so as to bring the friction contact members into pressure contact with the driven body.
2. The ultrasonic motor according to claim 1, wherein the engagement convex portion of the holder member has a cylindrical shape and the engagement concave portion of the accommodation hole in the position limiting member is formed in a prismatic shape.
3. The ultrasonic motor according to claim 2, wherein the sliding contact concave portion of the accommodation hole in the position limiting member is formed by chamfering.
4. The ultrasonic motor according to claim 3, wherein the holder member is formed of any one of resin material and rubber material and the pressure member is formed of a different material from the holder member, and is formed of any one of the resin material, the rubber material and metal material.
5. The ultrasonic motor according to claim 2, wherein the holder member is formed of any one of resin material and rubber material and the pressure member is formed of a different material from the holder member, and is formed of any one of the resin material, the rubber material and metal material.
6. The ultrasonic motor according to claim 1, wherein the sliding contact concave portion of the accommodation hole in the position limiting member is formed by chamfering.
7. The ultrasonic motor according to claim 6, wherein the holder member is formed of any one of resin material and rubber material and the pressure member is formed of a different material from the holder member, and is formed of any one of the resin material, the rubber material and metal material.
8. The ultrasonic motor according to claim 1, wherein the holder member is formed of any one of resin material and rubber material and the pressure member is formed of a different material from the holder member, and is formed of any one of the resin material, the rubber material and metal material.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. An electrode structure for a semiconductor device which is suitable for mounting on a circuit board in the face-down state, comprising:
a bump electrode formed on an aluminum electrode of said semiconductor device; and
an aluminum oxide film sufficient for the prevention of corrosion of the aluminum electrode, which is formed on a surface of said aluminum electrode exposed around said bump electrode.
2. The electrode structure for a semiconductor device as defined in claim 1, wherein said aluminum oxide film for the prevention of corrosion is obtained by further oxidizing a natural oxide film on the surface of said aluminum electrode.
3. The electrode structure for a semiconductor device as defined in claim 1, wherein the thickness of said aluminum oxide film is 5 to 20% of the thickness of said aluminum electrode.
4. The electrode structure for a semiconductor device as defined in claim 1, wherein the thickness of said aluminum oxide film is 0.05 to 0.2 m.
5. The electrode structure for a semiconductor device as defined in claim 1, wherein said bump electrode is made of Au.
6. A method for forming an electrode structure for a semiconductor device which is to be mounted on a circuit board in the face-down state, comprising the steps of:
forming a bump electrode on an aluminum electrode of said semiconductor device; and
forming an aluminum oxide film sufficient for the prevention of corrosion on a surface of said aluminum electrode that is exposed around said bump electrode.
7. The method for forming an electrode structure for a semiconductor device as defined in claim 6, wherein the bump electrode is formed by a wire bonding method using a Au wire.
8. The method for forming an electrode structure for a semiconductor device as defined in claim 6, wherein said aluminum oxide film is formed by exposing said semiconductor device having said bump electrode formed thereon to the high-temperature state.
9. The method for forming an electrode structure for a semiconductor device as defined in claim 8, wherein the high-temperature state has a temperature of 200 to 300 C.
10. The method for forming an electrode structure for a semiconductor device as defined in claim 9, wherein said aluminum oxide film is formed simultaneously at the step of forming the bump electrode at a temperature of 200 to 300 C.
11. The method for forming an electrode structure for a semiconductor device as defined in claim 6, where said aluminum oxide film is formed by immersing said semiconductor device having said bump electrode formed thereon in ammonium persulfate or hydrogen peroxide.
12. A mounted body including a semiconductor device, comprising a circuit board having a terminal electrode and a semiconductor device mounted on said circuit board in the facedown state, a bump electrode formed on an aluminum electrode of said semiconductor device and an aluminum oxide film sufficient for the prevention of corrosion which is formed on the surface of said aluminum electrode exposed around said bump electrode, the bump electrode being electrically connected to said terminal electrode on said circuit board through a bonding layer.
13. The mounted body including a semiconductor device as defined in claim 12, wherein said circuit board is formed from a board including an organic material.
14. The mounted body including a semiconductor device as defined in claim 12, wherein said aluminum oxide film for the prevention of corrosion is obtained by further oxidizing a natural oxide film on the surface of said aluminum electrode.
15. The mounted body including a semiconductor device as defined in claim 12, wherein said bonding layer is made of a conductive adhesive.
16. The mounted body including a semiconductor device as defined in claim 12, wherein said bonding layer is made of a solder.
17. The mounted body including a semiconductor device as defined in claim 12, wherein a gap between said semiconductor device and said circuit board is filled with an insulating resin.
18. The mounted body including a semiconductor device as defined in claim 12, wherein the thickness of said aluminum oxide film is 5 to 20% of the thickness of said aluminum electrode.
19. The mounted body including a semiconductor device as defined in claim 12, wherein the thickness of said aluminum oxide film is 0.05 to 0.2 m.
20. The mounted body including a semiconductor device as defined in claim 12, wherein said bump electrode is made of Au.
21. A semiconductor device suitable for mounting on a circuit board, comprising:
an aluminum electrode;
a bump electrode formed on said aluminum electrode; and
an aluminum oxide film sufficient for the prevention of corrosion of said aluminum electrode, which is formed on a surface of said aluminum electrode exposed around said bump electrode.