JP2000243202A - Micro-relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably open and close a contact without enlarging a micro-relay. SOLUTION: A movable contact 28 formed on a movable base 20 is brought into contact with and detached from a pair of fixed contacts 13, 14 provided in parallel with a fixed base 10 by driving the movable base 20 disposed opposite to the fixed base 10, so as to electrically open and close the both fixed contacts 13, 14. The movable contact 28 is rockably supported on the movable base 20 by an elastic supporting member 24, so that it can be brought into contact with or detached from the both fixed contacts 13, 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro relay that opens and closes contacts by driving a movable substrate based on electrostatic attraction, piezoelectric force, and the like.

[0002]

2. Description of the Related Art Generally, an ideal model for obtaining a large contact pressure in a micro relay has a configuration in which a movable electrode 201 and a fixed electrode 202 are parallel flat plates as shown in a schematic diagram of FIG. Then, a voltage is applied between the two electrodes to generate an electrostatic attraction, whereby the movable electrode 201
The movable contact 203 provided on the side is closed to a pair of fixed contacts 204 (one not shown) provided on the fixed electrode 202 side,
The two fixed contacts 204 are electrically connected.

[0003]

However, in the electrostatic micro relay having the above-described structure, a gap occurs between the movable electrode 201 and the fixed electrode 202 due to a processing error. Since the electrostatic attractive force is inversely proportional to the square of the gap, the electrostatic attractive force is large at a small gap and small at a large gap. Therefore, imbalance occurs in the electrostatic attraction, and FIG.
As shown in (b), the movable electrode 201 is a fixed electrode 202
Approach in a state inclined to. As a result, the movable contact 2
03 frequently contacts the fixed contacts 204 and 205, which lowers the contact reliability.

In the electrostatic micro relay, FIG.
As illustrated in FIG.
And the fixed contacts 204 may not be closed at the same time. Further, since the film is formed by a semiconductor process, as shown in FIGS. 9 (b) and 9 (c), the thickness of the film varies, and the movable contact 203 and each fixed contact 204,
There is a possibility that the same influences on the height dimension of 205 and the same problem as described above occurs. In this case, in order to close the movable contact 203 to both fixed contacts 204, it is necessary to increase the electrostatic attraction. When the required electrostatic attraction increases, the facing area between the two electrodes 201 and 202 must be increased, and the size cannot be avoided. These problems also occur for piezoelectric microrelays.

Accordingly, an object of the present invention is to provide a micro relay that can surely close a contact without increasing the size.

[0006]

According to the present invention, as a means for solving the above-mentioned problems, a movable substrate disposed opposite to a fixed substrate is driven, and a pair of fixed contacts arranged in parallel with the fixed substrate are provided. In a microrelay in which the fixed contacts are electrically opened and closed by moving and separating the movable contacts formed on the movable substrate, the movable substrate can be moved toward and away from the fixed contacts. The rocking support.

With this configuration, even if the movable contact comes into contact with one of the fixed contacts first, the movable contact swings without increasing the electrostatic attraction.
The remaining fixed contact also reliably contacts.

The movable contact may be swingably supported by a narrow elastic support portion perpendicular to the direction in which the fixed contacts are arranged, or may be swingably supported by a thin elastic support portion orthogonal to the direction in which the fixed contacts are arranged. do it.

[0009]

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

FIG. 1 and FIG. 3 show an electrostatic micro relay according to the present embodiment. This electrostatic micro relay is provided with a movable substrate 2 on an upper surface of a fixed substrate 10 made of a glass substrate 11a.
0 are integrated.

The fixed substrate 10 includes a glass substrate 11a.
The fixed electrode 12 and the fixed contacts 13 and 14 are formed on the upper surface of. The surface of the fixed electrode 12 is covered with an insulating film 15. The fixed electrode 12 and the fixed contacts 13 and 14 are
They are connected to connection pads 16, 17, 18 via printed wirings 16 a, 17 a, 18 a, respectively.

The movable substrate 20 is composed of four first thin plates extending laterally along the anchor 21 from the inner edge of the upper surface of the partially cut frame-shaped anchor 21 erected around the upper surface of the fixed substrate 10. The movable electrode 25 is supported via the beam 22.

The anchor 21 is connected to the connection pad 19 via a printed wiring 19a provided on the upper surface of the fixed substrate 10. The movable electrode 25 includes a pair of substantially U-shaped openings 26b and 26c at the center thereof, and a movable contact portion 23 and a second thin plate beam portion 24 that supports the movable contact portion 23 in a swingable manner. It corresponds to the elastic support of the invention.)
Are formed. A movable contact 28 is provided at the center of the lower surface of the movable contact portion 23 via an insulating film 27.
The movable contact 28 is opposed to the fixed contacts 13 and 14 so as to be able to contact and separate therefrom. The second thin plate beam portion 24 includes the fixed contact 13,
14 are formed so as to be orthogonal to the juxtaposition direction of FIG.
Medium, up and down). The width dimension of the second thin plate beam portion 24 is the movable contact portion 2
3, the movable contact portion 23 swings so as to be able to contact and separate from the fixed contacts 13 and 14. Therefore, for example, the fixed contacts 13,
Even if there is a variation in the height dimension due to a film formation error between the two, the second thin-film beam portion 24 absorbs this variation, and the movable contact 28 can be reliably formed without requiring an extra force. Can be closed to both fixed contacts 13 and 14.

Although the second thin beam portion 23 is formed by substantially U-shaped openings 26b and 26c, as shown in FIG. 5, the movable contact portion is formed by simply providing slits 29a and 29b. You may make it form the 2nd thin beam part 23 of the same width dimension as 23. In this case, the movable contact portion 23 may be swingable by forming the concave portions 30 on the lower surface of the second thin beam portion 23 so as to be thinner than the other portions. Further, as shown in FIG. 6, the concave portions 30 may be formed on the lower surface of the second thin beam portions 23 formed by the openings 26b and 26c, respectively, to be thin. According to this, it is possible to make the movable contact portion 23 swing more freely so that a smooth contact closing operation can be performed. The width and thickness of the second thin beam portion 23 may be arbitrarily set according to various conditions such as the above-described film formation error. Thereby, the swing state of the movable contact portion 23 can be made appropriate according to the processing conditions.

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 1 is placed on a glass substrate 11a such as Pyrex shown in FIG.
2. The fixed contacts 13 and 14 are formed. At the same time, printed wirings 16a, 17a, 18a, 19a and connection pads 16, 17, 18, 19 are formed, respectively. Then, by forming an insulating film 15 on the fixed electrode 12, the fixed substrate 10 shown in FIG. 3C is completed.

The insulating film 15 has a relative dielectric constant of 3 to 3.
If a silicon oxide film of No. 4 or a silicon nitride film of a relative permittivity of 7 to 8 is used, 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 comprising 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 using TMAH using the oxide film as a mask, an anchor 21 projecting downward is formed as shown in FIG. Then, as shown in FIG. 3F, after providing the insulating film 27, the movable contact 28 is formed.

Next, as shown in FIG. 3G, the SOI wafer 100 is joined to the fixed substrate 10 by anodic bonding. Then, as shown in FIG.
The upper surface of the wafer 100 is etched down to a silicon oxide layer 102, which is an oxide film, with an alkaline etchant such as TMAH or KOH. Further, the silicon oxide layer 102 is removed with a fluorine-based etchant to expose the silicon layer 102, that is, the movable electrode 25, as shown in FIG. Then, die cutting etching is performed by dry etching using RIE or the like, so that the notch 26a and the opening 2 are formed.
6b, 26c to form the first and second thin plate beam portions 22, 23.
And the movable substrate 20 is completed.

The fixed substrate 10 is not limited to the glass substrate 11a, but may be formed of a single crystal silicon substrate having at least an upper surface covered with an insulating film.

In the above embodiment, the entire movable substrate 20 is formed as a single silicon wafer, and is formed so as to be symmetric with respect to the right and left points and symmetrical in section. Therefore, the movable electrode 25 is less likely to warp or twist. Therefore, inoperability and variation in operation characteristics can be effectively prevented.
Smooth operation characteristics can be secured.

Next, the operation of the electrostatic micro relay having the above configuration will be described with reference to the schematic diagram shown in FIG. Here, as an example, a case where the movable contact 28 is higher on the side facing the fixed contact 13 due to a variation in film formation will be described.

First, when no voltage is applied between the fixed electrode 12 and the movable electrode 25, FIGS. 1B and 4A
As shown in the figure, the fixed electrode 12 and the movable electrode 25 maintain a parallel state, and the movable contact 28 is separated from the fixed contacts 13 and 14.

Next, when a voltage is applied between the movable electrode 12 and the fixed electrode 25, as shown in FIG.
The movable electrode 25 is attracted to the fixed electrode 12 by the electrostatic attraction generated between the fixed electrodes 12. For this reason, the first thin plate beam portion 22
Is bent, and the movable electrode 25 approaches the fixed electrode 12. As a result, the gap is narrowed, so that the movable electrode 25
Is attracted by stronger electrostatic attraction. Movable contact 28
Since the height dimension differs depending on the location due to the variation in film formation, first, as shown in FIG.
Contact 3 The movable contact 28 is provided in the second thin plate beam 2.
4, the fixed contact 14 is instantaneously closed. For this reason, the movable contact 28 is reliably fixed to both fixed contacts 13, regardless of the variation in the height dimension.
14, the operation is not delayed.

After the movable contact 28 comes into contact with the fixed contacts 13 and 14, the second thin beam portion 24 bends in addition to the first thin beam portion 22 as shown in FIG. The insulating film 15 covering the fixed electrode 12 is adsorbed. Accordingly, the movable contact 28 is pressed against the fixed contacts 13 and 14 via the second thin plate beam portion 24 by the surrounding movable electrode 25 being attracted to the fixed electrode 12, and a desired contact pressure is obtained.

By the way, the first and second thin plate beam portions 22 and 23
, The force pulling the movable electrode 25 upward, the electrostatic attraction between the movable electrode 25 and the fixed electrode 12 via the insulating film 15, and the drag force from the surface of the insulating film 15 as F _s1 , F _s2 , F _e , respectively. If F _n , the following relationship is established, and the first and second thin beam portions 22 and 23
Spring coefficient of, reducing the F _n, F _s1 by designing the movable electrode 25 initial gap between the fixed electrode 12, the contact of the thickness, and the like, F _s2, i.e. suppress a decrease in contact load (from the ideal model) It is possible.

[0027]

[Number 1] _{F e = F s1 + F s2} + F n

Therefore, when the application of the above-mentioned voltage is stopped, the movable electrode 25 is separated from the fixed electrode 12 by the elastic force of the second thin plate beam portion 24 and the first thin plate beam portion 22.
The movable contact 28 is fixed to the fixed contact 1 only by the elastic force of the thin plate beam portion 22.
The movable electrode 25 returns to its original state.

In the above embodiment, the movable electrode 25 has a flat shape, but a concave portion may be formed on the upper surface to make the movable electrode 25 thin. As a result, the operating speed and the return speed can be further improved even if the weight is low while securing the desired rigidity.

An insulating film may be formed on the lower surface of the movable electrode 25, and a second movable electrode and an insulating film may be sequentially laminated and integrated on the lower surface. This makes it possible to form the second movable electrode with a material having a high dielectric constant, and to obtain a larger electrostatic attraction.

Further, the movable electrode 25 is connected to the thin plate beam portion 22,
The rigidity may be increased as a thickness greater than 24. As a result, all of the electrostatic attraction can be used as the attraction to the movable electrode 25, and the electrostatic attraction can be efficiently reduced to the first thin plate beam portion 2.
2 can be used.

Further, a projection may be provided at the peripheral edge of the lower surface of the movable electrode 25 to further increase the electrostatic attractive force at the beginning of the operation.

In the above embodiment, the movable substrate is supported by the four first thin beam portions. However, the movable substrate may be supported by three or two first thin beam portions. This makes it possible to obtain an electrostatic microrelay with high area efficiency. Specifically, the movable substrate 25 supported by two first thin beam portions is shown in FIG. This has the same configuration as that shown in FIG. 1 except that two first thin plate beam portions 22 are provided.

In the above embodiment, the case where the features of the present invention are applied to an electrostatic micro relay that operates by electrostatic attraction as a micro relay has been described. It is also possible to apply to a micro relay.

[0035]

As is clear from the above description, according to the micro relay of the present invention, the movable contact is swingably supported on the movable substrate so as to be able to contact and separate from the fixed contacts. Even if the movable contact collides with one of the fixed contacts, the contact can be surely closed without the need to increase the electrostatic attraction by swinging.
Therefore, the size does not increase.

In particular, since the movable contact is swingably supported by the elastic support portions on both sides perpendicular to the direction in which the fixed contacts are juxtaposed,
It is possible to stabilize the supporting and swinging state of the movable contact.

Further, since the elastic support portion is constituted by a beam narrower than the distance of the fixed contact, it is possible to swing the movable contact with good responsiveness and close the contact.

[Brief description of the drawings]

FIG. 1 is a plan view (a) and a cross-sectional view (b) of a microrelay according to the present embodiment.

FIG. 2 is a perspective view showing a state where a fixed substrate and a movable substrate of FIG. 1 are disassembled.

FIG. 3 is a cross-sectional view showing the manufacturing process of FIG. 1;

FIG. 4 is a schematic diagram showing an operation state of the micro relay of FIG.

5A and 5B are a schematic plan view and a cross-sectional view showing another example of the movable contact portion shown in FIG.

6A is a schematic plan view showing another example of the movable contact portion in FIG. 1 and FIG. 6B is a cross-sectional view thereof.

FIG. 7 is a plan view showing another example of the second thin beam portion shown in FIG.

FIG. 8 is a sectional view of a micro relay according to a conventional example.

FIG. 9 is a schematic diagram showing a bad example of a contact structure according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Fixed substrate 11a ... Glass substrate 12 ... Fixed electrode 13, 14 ... Fixed contact 15 ... Insulating film 16, 17, 18, 19 ... Connection pad 16a, 17a, 18a, 19a ... Printed wiring 20 ... Movable substrate 21 ... Anchor 22 ... First thin plate beam part 23... Movable contact part 24... Second thin plate beam part 25 .. movable electrode 26 a... Cutout part 26 b and 26 c.

Claims (3)

[Claims] 1. A method according to claim 1, further comprising: driving a movable substrate disposed opposite to the fixed substrate, and bringing the movable contact formed on the movable substrate into and out of contact with a pair of fixed contacts arranged in parallel with the fixed substrate. A micro relay, wherein the movable contact is swingably supported by the movable substrate so as to be able to contact and separate from the fixed contacts. 2. The microrelay according to claim 1, wherein the movable contact is swingably supported by a narrow elastic support portion orthogonal to a direction in which the fixed contacts are arranged. 3. The microrelay according to claim 1, wherein the movable contact is swingably supported by a thin elastic supporting portion orthogonal to a direction in which the fixed contacts are arranged.