JPH11134998A - Electrostatic micro relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a designed operating characteristic hard to generate the thermal stress and thermal deflection by collecting plural anchors for standing at a part in a top surface of a base, and supporting a movable electrode through a thin plate beam part extended to the side from an upper edge of the anchor. SOLUTION: An electrostatic micro relay is formed by integrally forming an actuator 20 with a top surface of a base 10 formed of a glass substrate 11, and the base 10 is provided with a pair of fixed electrodes 12, 12 on the top surface of the glass substrate 11 in parallel with each other with the predetermined space, and a pair of fixed contacts 13, 14 are arranged in parallel with each other between the fixed electrodes 12, 12. The actuator 20 is formed of four anchors 21 stood on the top surface of the base 10, a first thin plate beam part 22, a pair of movable electrodes 23, 23, and a second thin plate beam part 24 for connecting the movable electrodes 23, 23. The anchors 21 are arranged near the periphery of the fixed contacts 13, 14 so as to surround them. The first thin plate beam part 22 is cut at a T-shaped notch part 26a and a slit 26b so as to support the movable electrode 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic micro-relay driven by an electrostatic attraction.

[0002]

2. Description of the Related Art Heretofore, as an electrostatic micro relay, for example, an electrostatic micro relay in which an actuator made of single crystal silicon which is inexpensive and easy to process is mounted on an upper surface of a base made of glass such as Pyrex has been studied. . For example, anchors are respectively erected at corners of the upper surface of a base made of a square glass substrate, and hinge portions are laterally extended from edges of the upper surface of the anchors. Further, a movable electrode facing a fixed electrode provided at the center of the upper surface of the base is connected to and supported at the tip of the hinge.

[0003] When a voltage is applied between the fixed electrode and the movable electrode, the movable electrode is attracted to the fixed electrode by an electrostatic attraction generated between the opposing electrodes, and the tip of the hinge part is bent downward. . For this reason, after the movable contact provided on the lower surface of the movable electrode via the insulating film contacts the fixed contact provided on the base, the movable electrode is attracted to the fixed electrode via the insulating film.

[0004]

However, in the above-mentioned electrostatic microrelay, the actuator made of single-crystal silicon is placed and positioned on the base made of a glass substrate, and then heated to a temperature of about 400.degree. Was subjected to anodic bonding in a state of being heated and expanded. The actuator is fixed to the four corners as a base, and the difference in thermal expansion coefficient between the glass base and the actuator made of single crystal silicon is large, and there is a large difference in the amount of contraction between the two. For this reason, when the above-mentioned electrostatic micro relay is cooled and returned to normal temperature, thermal stress is generated, thermal strain is generated, and components,
In particular, the actuator is easily deformed. As a result, there is a problem that operating characteristics as designed values cannot be obtained in driving voltage, contact load, operating speed, and the like.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an electrostatic micro-relay that is less likely to generate thermal stress and thermal strain and that can obtain operating characteristics as designed.

[0006]

In order to achieve the above object, an electrostatic microrelay according to the present invention comprises a fixed electrode provided on an upper surface of a base and a movable electrode of an actuator fixed on the upper surface of the base. An electrostatic microrelay that drives the movable electrode by electrostatic attraction generated by applying a voltage to the base and opens and closes an electric circuit by moving a movable contact provided on the actuator to a fixed contact provided on the base,
A plurality of anchors are concentrated and erected at one location on the upper surface of the base, and the movable electrode is supported via a thin plate beam extending laterally from the upper edge of the anchor.

A fixed electrode provided on the upper surface of the base;
The movable electrode is driven by electrostatic attraction generated by applying a voltage between the movable electrode of the actuator fixed to the upper surface of the base and the movable contact provided on the actuator is brought into contact with and separated from the fixed contact provided on the base. In the electrostatic micro relay, which opens and closes an electric circuit, the movable electrode of the actuator is provided with at least one thin plate beam extending laterally from an upper end edge of one anchor erected on the upper surface of the base. It may be configured to be supported via a.

[0008] The movable electrode may be connected to and supported on a free end of a thin plate beam portion extending outward from an upper end edge of the anchor.

[0009] The fixed contact may be disposed near a base of the anchor. An anchor may be provided upright in the vicinity of the four sides of the fixed contact.

[0010] The base may be glass while the actuator may be monocrystalline silicon or polycrystalline silicon.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment according to the present invention will be described with reference to the accompanying drawings of FIGS. As shown in FIGS. 1 to 4, the electrostatic micro relay according to the first embodiment has an actuator 20 integrated on an upper surface of a base 10 made of a glass substrate 11.

The base 10 has a pair of fixed electrodes 12, 12 arranged on the upper surface of a glass substrate 11 at predetermined intervals, and a pair of fixed contacts 13, 14 arranged between them. The surfaces of the fixed electrodes 12, 12 are covered with insulating films (not shown). Further, a relay connection portion 19b for connecting the actuator 20 is provided near the fixed contact 13. The fixed electrodes 12, the fixed contacts 13, 14 and the relay connection 19b are connected to the printed wirings 16a, 17a, 18a, 19
are connected to the connection pads 16, 17, 18, and 19, respectively.

The actuator 20 includes four anchors 21 erected on the upper surface of the base 10, a first thin plate beam portion 22 extending laterally from an edge of the upper surface of the anchor 21, It comprises a pair of movable electrodes 23, 23 each of which is supported at both corners by the thin plate beam portion 22, and a second thin plate beam portion 24 connecting the movable electrodes 23, 23.

The anchor 21 is provided with the fixed contacts 13, 1
4 so as to surround them. Especially,
Of the four anchors 21, a step portion 21a is formed on one half of the lower end surface of one anchor 21. This step 21
a is connected to the connection pad 19 via a relay connection portion 19b provided on the upper surface of the base 10 and a printed wiring 19a.

The first thin plate beam portion 22 has a substantially T-shaped cutout portion 26 provided at the center of the opposite side of the silicon wafer.
a and a slit 26b continuous therefrom,
The movable electrode 23 is supported. The first thin plate beam portion 22 is configured to extend outward from the upper edge of the anchor 21. For this reason, even if the first and second thin beam portions 22 and 24 and the movable electrode 23 expand due to external heating, they can expand freely outward, so that thermal stress and thermal distortion hardly occur.

The second thin plate beam portion 24 is formed of a pair of substantially T-shaped notches 2 provided at the center of the opposite side of the silicon wafer.
6a and 26a. This second thin plate beam part 2
Reference numeral 4 denotes a movable contact 28 at the center of the lower surface via an insulating film 27.
Is provided. The movable contact 28 is opposed to the fixed contacts 13 and 14 so as to be able to come and go.

Next, a method of manufacturing the electrostatic micro relay having the above-described configuration will be described with reference to the accompanying drawings of FIGS. 2 (a) to 4 (d). First, fixed electrodes 12, 12, fixed contacts 13, 14, and a relay connection 19b are formed on a glass substrate 11 such as Pyrex shown in FIG. At the same time, the fixed electrode 12, the fixed contact 13,
14, and the printed wiring lines 16a, 17a, 18a, 19a continuous with the relay connection portion 19b, respectively.
The connection pads 16, 17, 18, and 19b are respectively formed (FIG. 2B). Next, an insulating film (not shown) is formed on the fixed electrode 12, whereby the base 10 is completed. 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, a large electrostatic attraction can be obtained and the contact load can be increased.

On the other hand, the SOI wafer 30 shown in FIG.
In order to form a gap between contacts on the lower surface of the substrate, for example, wet etching is performed by TMAH using a silicon oxide film as a mask. Thus, four anchors 21 are formed, and a step 21a is formed on the lower end surface of the one anchor 21 (FIG. 3B). Then, after the insulating film 27 is formed in the portion surrounded by the four anchors 21 (FIG. 3C), the movable contact 28 is formed (FIG. 3D).

Next, the SOI wafer 3 is
0 is bonded and integrated by anodic bonding (FIG. 4A). Then, the upper surface of the SOI wafer 30 is etched down to the oxide film 31 with an alkaline etchant such as TMAH, KOH or the like (FIG. 4B). Further, the oxide film 31 is removed with a fluorine-based etchant to expose the movable electrode 23 (FIG. 4C). Then, die cutting etching is performed by dry etching using RIE or the like. As a result, the notch 26a and the slit 26b are formed to cut out the first and second thin beam portions 22, 24, and unnecessary silicon wafers are removed (FIG. 4D).
The actuator 20 is completed.

According to this embodiment, the actuator 20
The whole is formed as a single silicon wafer, and is formed symmetrically to the left and right and symmetrically in cross section. Therefore, the movable electrode 25
Warp and twist are less likely to occur. As a result, there is an advantage that inoperability and variation in operation characteristics can be effectively prevented, and smooth operation characteristics can be ensured.

Next, the operation of the electrostatic micro relay having the above-described configuration will be described. First, when no voltage is applied between the fixed electrode 12 and the movable electrode 23,
And the movable electrode 23 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 fixed electrode 12 and the movable electrode 23, the movable electrode 23 is attracted to the fixed electrode 12 by an electrostatic attraction generated between the electrodes 12 and 23. For this reason, the first thin plate beam portion 22 is twisted and bent,
The free end of the movable electrode 23 approaches the fixed electrode 12 side. As a result, the gap is narrowed, and the movable electrode 23 is attracted by stronger electrostatic attraction. Then, after the movable contact 28 contacts the fixed contacts 13 and 14, the second thin plate beam portion 24 bends,
The entire movable electrode 23 is attracted to the fixed electrode 12 via an insulating film (not shown).

When the application of the above-mentioned voltage is stopped, the movable electrode 23 is separated from the fixed electrode 12 by the spring force of the second thin plate beam portion 24 and the first thin plate beam portion 22, and then the movable contact 28 is moved to the fixed contact 13, The movable electrode 23 returns to its original state.

As shown in FIG. 5, the electrostatic micro relay according to the second embodiment is a case in which the actuator 20 is supported by two anchors 21 erected on the upper surface of the base 10.

The base 10 has a pair of fixed electrodes 12 and 12 arranged on the upper surface of a glass substrate 11 at predetermined intervals, and a pair of fixed contacts 13 and 14 arranged between them. The surfaces of the fixed electrodes 12, 12 are covered with insulating films (not shown). Further, a relay connection portion 19b for connecting the actuator 20 is provided near the fixed contact 13. The fixed electrodes 12, the fixed contacts 13, 14 and the relay connection 19b are connected to the printed wirings 16a, 17a, 18a, 19
The connection pads 16, 17, 18, and 19 are respectively connected via a.

The actuator 20 includes two anchors 21 erected on the upper surface of the base 10, a first thin plate beam portion 22 extending laterally from an edge of the upper surface of the anchor 21, A substantially U-shaped movable electrode 23 supported by the thin plate beam portion 22, and a second
It is composed of a thin plate beam portion 24.

The anchor 21 is connected to the printed wiring 17.
a, 18a are disposed at opposing positions.
In particular, of the two anchors 21, a step 21a is formed on one half of the lower end surface of one anchor 21. This step portion 21a is connected to the relay connection portion 19 provided on the upper surface of the base 10.
b and the printed wiring 19a, and is connected to the connection pad 19.

The first thin plate beam portion 22 has a substantially T-shaped notch 26a provided at the center of one side edge of the silicon wafer.
And a slit 26b continuous therewith, and supports the movable electrode 23. This first thin plate beam portion 22
The structure extends outward from the edge of the upper surface of the anchor 21. Therefore, the first thin plate beam portion 22 is heated from outside.
Even if the movable electrode 23 expands, they can freely expand outward, so that thermal stress and thermal distortion hardly occur.

The second thin plate beam portion 24 is cut out by a slit 26c and a substantially T-shaped cutout portion 26a provided on one side edge of the silicon wafer. This second thin plate beam portion 24
Is provided with a movable contact 28 at the center of the lower surface thereof via an insulating film 27. The movable contact 28 is opposed to the fixed contacts 13 and 14 so as to be able to come and go. The second
The manufacturing method and the operation of the electrostatic micro relay according to the embodiment are substantially the same as those of the first embodiment, and the description thereof is omitted.

According to the present embodiment, since the number of the anchors 21 is reduced while securing a desired deflection, there is an advantage that the manufacturing is simplified.

As shown in FIG. 6, the electrostatic micro relay according to the third embodiment is a case where the actuator 20 is supported by a single anchor 21 erected on the upper surface of the base 10. That is, the base 10 is a glass substrate 1
A fixed electrode 12 is provided on the upper surface of the device 1, and fixed contacts 13 and 14 are juxtaposed near one side thereof. The surface of the fixed electrode 12 is covered with an insulating film (not shown). A relay connection portion 19b for connecting and supporting an actuator 20 is provided near the fixed contacts 13 and 14.
Is provided. Further, the fixed electrode 12, the fixed contacts 13, 14 and the relay connection portion 19b are connected to the connection pad 1 via the printed wiring 16a, 17a, 18a, 19a.
6, 17, 18, and 19, respectively.

The actuator 20 includes an anchor 21 erected on the upper surface of the base 10 and an anchor 2
A pair of first thin beam portions 22, 22 laterally extending on the same axis from the upper surface edge of the upper electrode 1, a movable electrode 23 having both ends corner portions supported by the two thin beam portions 22, Slit 2
6c and the second thin plate beam portion 2 cut out by the through hole 26d
4 and 4.

The anchor 21 has a step 21a at one half of the lower end surface. The step portion 21a is connected to the connection pad 19 via a relay connection portion 19b provided on the upper surface of the base 10 and a printed wiring 19a.

The first thin plate beam portion 22 is cut out by providing a through hole 26d near one edge of the silicon wafer. In the present embodiment, the first thin beam portions 22 extend outward from the upper edge of the anchor 21, and the movable electrode 23 extends from the first thin beam portions 22. Therefore, even if the first thin plate beam portion 22 and the movable electrode 23 expand due to heating, they can expand freely outward, so that thermal stress and thermal distortion hardly occur.

A movable contact 28 is provided in the center of the lower surface of the second thin plate beam portion 24 via an insulating film 27. The movable contact 28 is opposed to the fixed contacts 13 and 14 so as to be able to come and go.

The manufacturing method and the operation of the electrostatic micro relay according to the third embodiment are almost the same as those of the first embodiment, and the description is omitted.

[0037]

As is apparent from the above description, according to the electrostatic micro relay according to the first aspect of the present invention, a plurality of anchors are erected at one place on the upper surface of the base. Therefore, the distance between anchors is short. Therefore, even after the base and the actuator having a large difference in thermal expansion coefficient are joined and integrated in an expanded state, even when the temperature is returned to normal temperature, the amount of contraction between the anchors is small. As a result, thermal stress and thermal strain are small, and deformation generated in the actuator is small, so that operating characteristics according to design values in driving voltage, contact load, operating speed and the like can be obtained.

According to the second aspect, the thin beam portion extends laterally from the upper end edge of the one anchor erected on the base, and the movable electrode is connected to and supported by the thin beam portion. . For this reason, even if the base and the actuator having a large difference in thermal expansion coefficient are joined and integrated in an expanded state and then returned to room temperature, the thermal stress and thermal distortion unlike the conventional example do not occur. As a result, there is no deformation occurring in the actuator, and operation characteristics as designed in drive voltage, contact load, operation speed and the like can be obtained.

According to the third aspect, the movable electrode is connected to and supported by the free end of the thin plate beam extending outward from the upper edge of the anchor. For this reason, even if it heats to join and integrate the actuator with the base, the actuator can freely expand outward. As a result, the actuator itself does not generate thermal stress or thermal strain and does not deform, so that the operating characteristics according to the design values can be further obtained in the driving voltage, the contact load, the operating speed, and the like.

According to the fourth aspect, the fixed contact is disposed near the base of the anchor. Therefore, the movable contact that contacts the fixed contact is located closer to the anchor than the movable electrode. As a result, when the movable electrode is attracted to the fixed electrode by electrostatic attraction, the movable contact comes into contact with the fixed contact with a large contact load by the principle of leverage, so that a malfunction does not occur due to external vibration or the like. In particular, according to the fifth aspect, the thin beam portion extends from the four anchors arranged near the four sides of the fixed contact. For this reason, since the movable contact comes into contact with the fixed contact with the contact load applied from all directions, a malfunction is more unlikely to occur.

According to the sixth aspect, even if the silicon actuator is integrated with the glass base by anodic bonding, the structure has the above-described structure, so that the operating characteristics according to the design values in drive voltage, contact load, operating speed, and the like are attained. There is an effect that an electrostatic micro relay having the following is obtained.

[Brief description of the drawings]

1A and 1B show an electrostatic micro relay according to a first embodiment of the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along the line 1B-1B in FIG. (C) is FIG.
It is 1C-1C sectional view taken on the line of (a).

FIG. 2 is a process flow for manufacturing the base shown in FIGS. 1 (a) to 1 (c).

FIG. 3 is a process flow for manufacturing the actuator shown in FIGS. 1 (a) to 1 (c).

FIG. 4 is a process flow for manufacturing the electrostatic micro relay shown in FIGS. 1 (a) to 1 (c).

FIG. 5 is a plan view showing an electrostatic micro relay according to a second embodiment of the present invention.

6A and 6B show an electrostatic micro relay according to a third embodiment of the present invention. FIG. 6A is a plan view, and FIG. 6B is a sectional view taken along line 6B-6B in FIG. 6A.

[Explanation of symbols]

10: Base, 11: Silicon wafer, 12: Fixed electrode, 13, 14: Fixed contact, 16, 17, 18, 19 ...
Connection pad 19b Relay connection portion 20 Actuator 21 Anchor 22 First thin beam portion 23 Movable electrode 24 Second thin beam portion 28 Movable contact

Claims (6)

[Claims] 1. A movable electrode is driven by an electrostatic attraction generated by applying a voltage between a fixed electrode provided on an upper surface of a base and a movable electrode of an actuator fixed on the upper surface of the base. In an electrostatic microrelay for opening and closing an electric circuit by moving a movable contact provided on the actuator to and away from a fixed contact provided, a plurality of anchors are concentrated and erected at one location on the upper surface of the base. Wherein the movable electrode is supported via a thin beam extending laterally from an upper edge of the movable microelectrode. 2. The movable electrode is driven by an electrostatic attraction generated by applying a voltage between a fixed electrode provided on an upper surface of a base and a movable electrode of an actuator fixed on the upper surface of the base, and the movable electrode is attached to the base. An electrostatic microrelay that opens and closes an electric circuit by moving a movable contact provided on the actuator to and away from a fixed contact provided, wherein a movable electrode of the actuator is provided at an upper edge of one anchor erected on an upper surface of the base. An electrostatic micro-relay supported by at least one thin beam extending laterally from the portion. 3. The electrostatic micro device according to claim 1, wherein the movable electrode is connected to and supported by a free end of a thin beam portion extending outward from an upper end edge of the anchor. relay. 4. The electrostatic micro-relay according to claim 1, wherein the fixed contact is arranged near a base of the anchor. 5. The electrostatic micro relay according to claim 1, wherein anchors are provided upright on four sides of the fixed contact. 6. The electrostatic micro relay according to claim 1, wherein the base is made of glass, and the actuator is made of single crystal silicon or polycrystalline silicon.