Micro-switching device and method of manufacturing the same

• US 7,755,459 B2
• Filed: 01/14/2008
• Issued: 07/13/2010
• Est. Priority Date: 01/18/2007
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Mishima, Naoyuki, Ueda, Satoshi, Yonezawa, Yu, Nguyen, Anh Tuan, Nakatani, Tadashi
• Primary Examiner(s): Takaoka; Dean O
• Application Number:
  US12/007,630
• Publication Number:
  US 20080174390A1
• Time in Patent Office: 911 Days
• Field of Search: 333/101, 333/103, 333/104, 333/105, 333/262, 335/78, 200/181
• US Class Current: 333/262
• CPC Class Codes: H01H 2057/006 Micromechanical piezoelectric relay
• CPC Class Codes: H01H 2061/006 Micromechanical thermal relay
• CPC Class Codes: H01H 57/00 Electrostrictive relays; Piezoelectric relays
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 61/04 wherein the thermally-sensitive member is only heated directly
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A micro-switching device includes a fixing portion, a movable portion, a first electrode with first and second contacts, a second electrode with a third contact contacting the first contact, and a third electrode with a fourth contact opposing the second contact. In manufacturing the micro-switching device., the first electrode is formed on a substrate, and a sacrifice layer is formed on the substrate to cover the first electrode. Then, a first recess and a shallower second recess are formed in the sacrifice layer at a position corresponding to the first electrode. The second electrode is formed to have a portion opposing the first electrode via the sacrifice layer, and to fill the first recess. The third electrode is formed to have a portion opposing the first electrode via the sacrifice layer; and to fill the second recess. Thereafter the sacrifice layer is removed.

Claims

1. A micro-switching device comprising:

a fixing portion;

a movable portion including a first surface and a second surface opposite to the first surface, the movable portion including a stationary end fixed to the fixing portion;

a movable contact electrode provided on the first surface of the movable portion and including a first contact portion and a second contact portion;

a first stationary contact electrode including a third contact portion coming into contact with the first contact portion of the movable contact electrode, the first stationary contact electrode being joined to the fixing portion;

a second stationary contact electrode including a fourth contact portion facing the second contact portion of the movable contact electrode, the second stationary contact electrode being joined to the fixing portion; and

a driving mechanism for moving the movable portion to cause the second contact portion and the fourth contact portion to come into contact with each other;

wherein when the moveable portion is in a natural state, the first contact portion is held in contact with the third contact portion, and the second contact portion is separated from the fourth contact portion.

2. The micro-switching device according to claim 1, wherein the first contact portion of the movable contact electrode and the third contact portion of the first stationary contact electrode are connected to each other.

3. The micro-switching device according to claim 1, wherein the movable contact electrode comprises a first projecting portion and a second projecting portion, the first projecting portion including the first contact portion, the second projecting portion having a shorter projecting length than the first projecting portion and including the second contact portion.

4. The micro-switching device according to claim 1, wherein the first stationary contact electrode comprises a third projecting portion including the third contact portion, the second stationary contact electrode comprising a fourth projecting portion having a shorter projecting length than the third projecting portion and including the fourth contact portion.

5. The micro-switching device according to claim 1, wherein the movable contact electrode is spaced from the stationary end in a offset direction on the first surface of the movable portion, the first contact portion and the second contact portion being spaced in a direction intersecting the offset direction, the driving mechanism including a driving force generation region on the first surface of the movable portion, the driving force generation region having a center of gravity closer to the second contact portion than to the first contact portion of the movable contact electrode.

6. The micro-switching device according to claim 5, wherein a distance between the stationary end of the movable portion and the first contact portion of the movable contact electrode is different from a distance between the stationary end and the second contact portion.

7. The micro-switching device according to claim 5, wherein the movable portion has a bent structure.

8. The micro-switching device according to claim 5, wherein the center of gravity of the driving force generation region and the second contact portion are located on a same side with respect to an imaginary line passing through a midpoint of the length of the stationary end and a midpoint between the first contact portion and the second contact portion.

9. The micro-switching device according to claim 1, wherein the driving mechanism includes a movable driving electrode and a stationary driving electrode, the movable driving electrode being provided on the first surface of the movable portion, the stationary driving electrode being joined to the fixing portion and having a portion opposing the movable driving electrode.

10. The micro-switching device according to claim 1, wherein the driving mechanism includes a multilayer structure made up of a first electrode layer provided on the first surface of the movable portion, a second electrode layer, and a piezoelectric layer arranged between the first electrode layer and the second electrode layer.

11. The micro-switching device according to claim 1, wherein the driving mechanism includes a multilayer structure made up of a plurality of material layers provided on the first surface of the movable portion, each of the material layers having a different thermal expansion coefficient.

14. The micro-switching device according to claim 1, wherein the natural state is an elastically relaxed state.

12. A method of manufacturing a micro-switching device comprising:

a fixing portion;

a movable portion including a first surface and a second surface opposite to the first surface, the movable portion including a stationary end fixed to the fixing portion;

a movable contact electrode provided on the first surface of the movable portion and including a first contact portion and a second contact portion;

a first stationary contact electrode including a third contact portion coming into contact with the first contact portion of the movable contact electrode, the first stationary contact electrode being joined to the fixing portion; and

a second stationary contact electrode including a fourth contact portion facing the second contact portion of the movable contact electrode, the second stationary contact electrode being joined to the fixing portion;

the method comprising the steps of;

forming the movable contact electrode on a substrate;

forming a sacrifice layer on the substrate to cover the movable contact electrode;

forming a first recess and a second recess in the sacrifice layer corresponding in position to the movable contact electrode, the second recess being shallower than the first recess;

forming the first stationary contact electrode having a portion opposing the movable contact electrode via the sacrifice layer, the first stationary contact electrode filling the first recess;

forming the second stationary contact electrode having a portion opposing the movable contact electrode via the. sacrifice layer, the second stationary contact electrode filling the second recess; and

removing the sacrifice layer.

13. A method of manufacturing a micro-switching device comprising:

a fixing portion;

a movable portion including a first surface and a second surface opposite to the first surface, the movable portion including a stationary end fixed to the fixing portion;

a movable contact electrode provided on the first surface of the movable portion and including a first contact portion and a second contact portion;

a first stationary contact electrode including a third contact portion connected to the first contact portion of the movable contact electrode, the first stationary contact electrode being joined to the fixing portion; and

a second stationary contact electrode including a fourth contact portion facing the second contact portion of the movable contact electrode, the second stationary contact electrode being joined to the fixing portion;

the method comprising the steps of;

forming the movable contact electrode on a substrate;

forming a sacrifice layer on the substrate to cover the movable contact electrode;

forming a through-hole and a recess in the sacrifice layer corresponding in position to the movable contact electrode, the through-hole partially exposing the movable portion;

forming the first stationary contact electrode to have a portion opposing the movable contact electrode via the sacrifice layer, the first stationary contact electrode filling the through-hole;

forming the second stationary contact electrode to have a portion opposing the movable contact electrode via the sacrifice layer, the second stationary contact electrode filling the recess; and

removing the sacrifice layer.