JP2001014997A - Electrostatic relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact structure that has high contact reliability and good electric connection with a signal line by providing at least one of contacts with a projection made of conductive material on the signal line formed on a substrate. SOLUTION: Contacts are preferably made of material having adhesiveness lower than that of a signal line in contact closing time, specifically preferably of Au alloy or platinum material. When a voltage is applied to a gap between a fixed electrode 5 and a movable electrode portion 12, electrostatic attraction occurs between the both to deflect a first support beam 10. At a time when tip side of the movable electrode portion 12 abuts on the fixed electrode 5, a movable contact 15 closes it to fixed contacts 7. The fixed contacts 7a, 7b are provided projecting from signal lines 4a, 4b, so that the contacts can be certainly closed before the movable electrode portion 12 is made to contact entirely with the fixed electrode 5. When the movable electrode portion 12 is attracted to the fixed electrode 5, a second support beam 11 deflects, and its elastic force serves as a force for pressing the movable contact 15 to the fixed contacts 7, namely as contact pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic relay for driving a movable electrode by electrostatic attraction to open and close a contact.

[0002]

2. Description of the Related Art Conventionally, as an electrostatic relay, for example, FIG.
(See Japanese Patent Application Laid-Open No. 4-58430). This electrostatic relay comprises a fixed substrate 200 and a movable substrate 2
01. On the upper surface of the fixed substrate 200, the protrusion 20
2 are formed, and the signal line 204 is interposed via the insulating film 203.
And a fixed electrode 205. One end of the signal line 204 is located on the convex portion 202 and forms a fixed contact 206. On the other hand, a movable electrode 207 and movable pieces 208 located on both sides thereof are formed on the movable substrate 201 by etching or the like. A signal line 209 is formed on the lower surface of the movable piece 208, and one end thereof is a movable contact 210.

In the above-mentioned electrostatic relay, between the electrodes 205, 20
When a voltage is applied to 7 to generate electrostatic attraction, the movable substrate 201 is driven, and the movable contact 210 provided thereon is closed to the fixed contact 206 provided on the convex portion 202 of the fixed substrate 200. In this case, since the fixed contact 206 is provided on the convex portion 202, the movable contact 210 can be closed to the fixed contact 206 before the movable electrode 207 is attracted to the fixed electrode 205, and the desired contact pressure can be reduced. It is possible to get.

[0004]

However, in the above-mentioned electrostatic relay, in order to surely close the contacts,
The aspect ratio of the protrusion 202 (here, the ratio h / l of the height h to the length 1 of the protrusion 202; the same applies hereinafter).
Need to be larger. For this reason, the projected area of the side surface of the convex portion 202 is reduced, and the signal line 2 formed by vapor deposition or the like is formed.
04 is difficult to form to a desired film thickness. As a result,
The signal line 204 is easily broken.

Therefore, the present invention has a high contact reliability,
It is an object of the present invention to provide an electrostatic relay having a contact structure with good electrical connection to a signal line.

[0006]

According to the present invention, as a means for solving the above-mentioned problems, a movable substrate provided opposite to a fixed substrate is driven by electrostatic attraction, and fixed contacts formed on the fixed substrate are provided with: An electrostatic relay configured to close a movable contact formed on the movable substrate, wherein at least one of the contacts has a configuration in which a projection made of a conductive material is provided on a signal line formed on the substrate. is there.

With this configuration, when the movable electrode is driven by electrostatic attraction, the movable contact is closed to the fixed contact before the movable electrode is attracted to the fixed electrode. Further, since the contact is formed by the projection made of a conductive material provided on the signal line, there is no possibility of disconnection even if the aspect ratio is increased.

It is preferable that the contact is made of a material having a smaller adhesiveness when closing the contact than the signal line, since the desired conductivity can be maintained and the adhesion of the contact can be appropriately prevented.

The contacts may be made of an Au alloy or a platinum-based material.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an electrostatic relay according to this embodiment. This electrostatic relay includes a fixed substrate 1 and a movable substrate 2.

The fixed substrate 1 has signal lines 4a, 4b, fixed electrodes 5, and pads 6a, 6b, 6 on the upper surface of the glass substrate 3.
c, 6d are formed. The signal lines 4 are arranged side by side at predetermined intervals, and fixed contacts 7a and 7b are provided at one end, and pads 6a and 6b are provided at the other end. The fixed electrode 5 is connected to the pad 6c, and has its surface covered with an insulating film 8
Is coated. The pad 6d is electrically connected to a movable electrode section 12 described later, and the pads 6a, 6b,
Lead wires (not shown) are connected to 6c and 6d.

The movable substrate 2 is provided on the upper surface of the fixed substrate 1,
An anchor 9 is integrated along the pads 6a, 6b, 6c, 6d, and the movable electrode portion 12 is elastically supported from the anchor 9 via a first support beam 10 and a second support beam 11. The anchor 9 is insulated from the pads 6a, 6b, 6c, and is electrically connected to the pad 6d. First support beam 1
Numeral 0 extends laterally from the center of the upper edge of the anchor 9, and a movable contact 15 is formed on the lower surface of the distal end thereof via an insulating layer 14 (see FIG. 2). The second support beams 11 extend from both sides of the first support beams 10 and elastically support the movable electrode unit 12.

Next, a method of manufacturing the electrostatic micro relay having the above-described configuration will be described.

First, as shown in FIG. 3B, a fixed electrode 5 and a signal line 4 are formed on the upper surface of the glass substrate 3 shown in FIG.
a, 4b (4a is not shown) and connection pads 6a,
6b, 6c and 6d (only 6c is shown) are formed, respectively. The signal lines 4a and 4b are formed by sputtering, depositing, plating, or screen printing Au. Also, one end of the formed signal lines 4a and 4b is
The fixed contacts 7a and 7b are formed by sputtering, vapor deposition, plating, screen printing, etc. of a u-alloy or a platinum-based conductive material (for example, Ru: ruthenium) in the same manner as described above. Therefore, the fixed contacts 7a and 7b and the signal line 4
The fixed contacts 7a and 7b having a large aspect ratio h / l can be formed while maintaining a good electrical connection between the fixed contacts 7a and 4b. Then, an insulating film 8 is formed on the fixed electrode 5 to complete the fixed substrate 1 shown in FIG. If a silicon oxide film having a relative dielectric constant of 3 to 4 or a silicon nitride film having a relative dielectric constant of 7 to 8 is used as the insulating film 8, a large electrostatic attraction can be obtained and the contact load can be increased.

On the other hand, as shown in FIG. 3D, in order to form a contact gap on the lower surface of the SOI wafer 100 composed of the silicon layer 101, the silicon oxide layer 102 and the silicon layer 103 from the upper surface side, for example, silicon By performing wet etching with TMAH using the oxide film as a mask, an anchor 9 projecting downward is formed as shown in FIG. In addition, a relief groove 13 is formed on the lower surface of the anchor 9. Then, after providing the insulating layer 14, the movable contact 1
5 is formed.

Next, as shown in FIG. 4A, the SOI wafer 100 is bonded to the fixed substrate 1 by anodic bonding. At this time, a glass frit is provided in the escape groove 13. Then, the upper surface of the SOI wafer 100 is
Thinning is performed up to the silicon oxide layer 102 which is an oxide film using an alkaline etching solution such as H or KOH. Further, the silicon oxide layer 102 is removed with a fluorine-based etchant to expose the silicon layer 103, that is, the movable electrode section 12, as shown in FIG. Thereafter, die cutting etching is performed by dry etching using a reactive ion etching method (RIE) or the like to form a first support beam 10 and a second support beam 11 (the second support beam 11 is not shown). The movable substrate 2 is completed.

Next, the operation of the electrostatic micro relay having the above configuration will be described.

In an initial state in which no voltage is applied between the fixed electrode 5 and the movable electrode portion 12, as shown in FIG. 2B, the movable electrode portion 12 includes the first support beam 10 and the second support beam. The horizontal state is maintained by the elastic force of No. 11. This allows
The movable contact 15 faces the fixed contact 7 at a predetermined interval.

Here, when a voltage is applied between the fixed electrode 5 and the movable electrode portion 12, an electrostatic attraction is generated between the two, and as shown in FIG. Bends.
The movable contact 15 closes to the fixed contact 7 when the distal end of the movable electrode portion 12 contacts the fixed electrode 5. Since the fixed contact 7 is provided so as to protrude from the signal line 4, the contact can be surely closed before the movable electrode portion 12 contacts the entire surface of the fixed electrode 5. Thereafter, as shown in FIG. 2D, when the movable electrode portion 12 is further attracted to the fixed electrode 5, the second support beam 11 bends, and the elastic force of the second support beam 11 presses the movable contact 15 against the fixed contact 7, That is, it acts as a contact pressure.

When the voltage applied between the fixed electrode 5 and the movable electrode portion 12 is removed, the electrostatic attraction disappears, and the movable electrode portion 12 firstly has the elasticity of the first support beam 10 and the second support beam 11. The force separates the vicinity of the contact closure. Then, the movable electrode portion 12 is separated from the fixed electrode 5 by the elastic force of the first support beam 10 and returns to the initial horizontal state, whereby the movable contact 15 is released from the fixed contacts 7a and 7b.

In the above embodiment, the movable electrode 12
Is a cantilever structure supported by the first support beam 10 and the second support beam 11, but if the contact structure according to the present invention,
Any other supporting form, such as a double-supported structure or a diaphragm structure, can be adopted.

Further, the fixed substrate 1 may be constituted by a silicon substrate. However, the insulating layer 1 is provided on the surface of the silicon substrate.
4 must be formed. Further, the movable substrate 2 may be constituted by a glass substrate. In this case, similarly to the fixed substrate 1, a signal line may be formed, and a movable contact made of a conductive material may be formed thereon.

[0024]

As is apparent from the above description, according to the electrostatic relay of the present invention, at least one of the contacts is provided with a projection made of a conductive material on the signal line formed on the substrate. Thus, it is possible to obtain a desired contact reliability, increase the aspect ratio without fear of disconnection, and increase the contact pressure.

Further, since the contact is made of a material having lower adhesiveness when the contact is closed than the signal line, the contact is excellent in detachability.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electrostatic relay according to an embodiment.

FIG. 2 is a plan view (a) of assembling the electrostatic relay of FIG. 1 and sectional views (b-d) taken along the line AA of each of the operating states.

FIG. 3 is a cross-sectional view showing a processing process of the electrostatic relay of FIG.

FIG. 4 is a cross-sectional view showing a processing process of the electrostatic relay of FIG.

FIG. 5 shows an electrostatic relay according to a conventional example.

FIG. 6 is a sectional view showing the contact structure of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixed board 2 ... Movable board 4a, 4b ... Signal line 5 ... Fixed electrode 7a, 7b ... Fixed contact 9 ... Anchor 10 ... First support beam 11 ... Second support beam 12 ... Movable electrode part 15 ... Movable contact

Claims (3)

[Claims] 1. An electrostatic relay for driving a movable substrate opposed to a fixed substrate by electrostatic attraction to close a fixed contact formed on the fixed substrate with a movable contact formed on the movable substrate. An electrostatic relay, wherein at least one of the contacts has a configuration in which a projection made of a conductive material is provided on a signal line formed on a substrate. 2. The electrostatic relay according to claim 1, wherein the contact is made of a material having lower adhesiveness when the contact is closed than a signal line. 3. The electrostatic relay according to claim 1, wherein the contact is made of an Au alloy or a platinum-based material.