Micro-device with thermal actuator

• US 20020097133A1
• Filed: 12/17/2001
• Published: 07/25/2002
• Est. Priority Date: 12/27/2000
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Dufour, Michel, Charvet, Pierre-Louis
• Granted Patent: US 6,703,916 B2
• Time in Patent Office: Days
• US Class Current: 337/27
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 2001/0063 having electrostatic latches, i.e. the activated position is kept by electrostatic forces other than the activation force
• CPC Class Codes: H01H 2037/008 Micromechanical switches operated thermally
• CPC Class Codes: H01H 2061/006 Micromechanical thermal relay
• CPC Class Codes: H01H 61/02 wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively

Abstract

The invention relates to a microswitch containing conductors located on a first level and conductors located on a second level, where the conductors on the first level are supported by a deformable element which can switch by means of an actuator with a bimetallic effect, and where the effect of this switching is that the gap between the conductors on the first level and the conductors on the second level is modified, characterised in that the actuator with a bimetallic effect consists of resistors in close and localised contact with the deformable element, and in that the resistors are capable, when traversed by an electric control current, of expanding sufficiently under the effect of the heat produced by the passage of the electric command current to cause, by the bimetallic effect, the deformable element to trigger before the heat produced in the resistors has been able to propagate into the deformable element.

Claims

1. A micro-device comprising conductors (13) located on a first level and conductors (4, 5) located on a second level, where the conductors (13) on the first level are supported by a deformable element (11) which is able to trigger by means of a bimetallic effect actuator, and where the effect of the triggering is to modify the distance between the conductors (13) on the first level and the conductors (4, 5) on the second level, characterised in that the bimetallic effect actuator consists of resistors (14, 15) in close and localised contact with the deformable element (11), and in that the resistors (14, 15) are capable, when they are traversed by an electric control current, of expanding sufficiently under the effect of the heat produced by the passage of the electrical control current to cause, through a bimetallic effect, the triggering of the deformable element (11) before the heat produced in the resistors (14, 15) has been able to propagate in the deformable element (11).

2. A micro-device in claim 1, characterised in that the deformable element is a member (11) or membrane.

3. A micro-device as claimed in either claims 1 or 2, characterised in that electrostatic holders are included to hold the deformable element (11) in its position after it is switched, when the electrical control current is cancelled.

4. A micro-device in claim 3, characterised in that the electrostatic holders include at least one pair of electrodes (16, 17;

18, 19) facing one another, and where one of these elements forms a single piece with the deformable element (11), and the other is positioned such that, when the deformable element has triggered, the distance between the facing electrodes is minimal.

5. A micro-device in claim 3, characterised in that the electrostatic holders include at least one pair of facing electrodes, and where one of these electrodes forms a single piece with the deformable element, the other being positioned such that, when the deformable element has triggered the electrodes are in contact with one another, but separated by electrical insulators.

6. A micro-device as claimed in any of claims 1 to 5, characterised in that the resistors (25) include at least one layer deposited in the form of a wave.

7. A micro-device as claimed in any of claims 1 to 6, characterised in that the resistors (14, 15) are made from a material chosen from aluminium, manganese, zinc, gold, platinum, nickel or inconel 600.

8. A micro-device as claimed in any of claims 1 to 7, characterised in that, with the micro-device being made using micro-technology techniques, the deformable element (11) originates from a layer (10) deposited on a substrate (1).

9. A micro-device as claimed in any of claims 1 to 8, characterised in that the conductors located on the second level include a first line contact (4) and a second line contact (5), and in that the effect of triggering the deformable element is to reduce to zero the distance between the conductors (13) on the first level and the conductors on the second level, with the conductors on the first level thus forming an electrical link between the first contact (4) and the second contact (5), and the micro-device thus constituting a microswitch.

10. A micro-device in claim 9, characterised in that the conductors supported by the deformable element are constituted by a conductive block (13).

11. A micro-device as claimed in any of claims 1 to 8, characterised in that the conductors on the first level and the conductors on the second level constitute respectively a first electrode and a second electrode of a condenser, and where this condenser has a first capacity value before the switching of the deformable element and a second capacity value after the switching of the deformable element.

12. A micro-device in claim 11, characterised in that an insulating layer of high dielectric constant separates the first electrode and the second electrode of the condenser.