JP3393467B2 - Electrostatic micro relay - Google Patents

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 electrostatic attraction.

[0002]

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

When a voltage is applied between the fixed electrode and the movable electrode, the movable electrode is attracted to the fixed electrode by the electrostatic attractive force generated between the opposing electrodes, and the tip of the hinge portion bends downward. . Therefore, 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 electrostatic microrelay described above, an actuator made of single crystal silicon is placed and positioned on a base made of a glass substrate and then heated to a temperature of about 400 ° C. Was anodic-bonded in a state of being thermally expanded. The actuator is fixed to the bases at the four corners, and the difference in the coefficient of thermal expansion between the glass base and the actuator 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 room temperature, thermal stress occurs, thermal strain occurs, and component parts,
In particular, the actuator is easily deformed. As a result, there is a problem that operating characteristics as designed values cannot be obtained in terms of driving voltage, contact load, operating speed, and the like.

In view of the above problems, it is an object of the present invention to provide an electrostatic microrelay in which thermal stress and thermal strain are unlikely to occur and operating characteristics as designed are obtained.

[0006]

In order to achieve the above-mentioned object, an electrostatic micro relay according to the present invention is provided between a fixed electrode provided on the upper surface of a base and a movable electrode of an actuator fixed on the upper surface of the base. In the electrostatic microrelay for driving the movable electrode by an electrostatic attractive force generated by applying a voltage to, and opening and closing an electric circuit by bringing the fixed contact provided in the base into contact with and separated from the movable contact provided in the actuator,
A plurality of anchors are concentrated and erected in one place on the upper surface of the base, and the movable electrode is supported via a thin plate beam portion laterally extending from the upper end edge of the anchor.

Further, a fixed electrode provided on the upper surface of the base,
The movable electrode is driven by an electrostatic attraction generated by applying a voltage between the movable electrode of the actuator fixed on 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 an electrostatic micro relay for opening and closing an electric circuit, the freedom of at least one thin plate beam portion extending laterally and outward from the upper edge of one anchor standing on the upper surface of the base. It may be an electrostatic micro relay characterized in that the movable electrode of the actuator is connected and supported at the end.

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

The fixed contact may be arranged near the base of the anchor. In addition, anchors may be provided upright near the four sides of the fixed contact.

While the base is glass, the actuator may be single crystal silicon or polycrystalline silicon.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of 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 the upper surface of a base 10 made of a glass substrate 11.

The base 10 has a pair of fixed electrodes 12 and 12 arranged in parallel on the upper surface of a glass substrate 11 at a predetermined interval, and a pair of fixed contacts 13 and 14 between them. The surfaces of the fixed electrodes 12 and 12 are covered with an insulating film (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 and 14 and the relay connection portion 19b are connected to the printed wirings 16a, 17a, 18a and 19 respectively.
They are connected to the connection pads 16, 17, 18, and 19 via a, respectively.

The actuator 20 includes four anchors 21 provided upright on the upper surface of the base 10, a first thin plate beam portion 22 laterally extending from an upper edge of the anchor 21, and two anchors 22. A pair of movable electrodes 23, 23 whose both corners are respectively supported by the thin plate beam portion 22 of the book, and a second thin plate beam portion 24 connecting the movable electrodes 23, 23 are formed.

The anchor 21 includes the fixed contacts 13, 1
4 are arranged so as to be surrounded in four directions. In particular,
A step portion 21 a is formed on one half of the lower end surface of one anchor 21 among the four anchors 21. This step 21
a is connected to the connection pad 19 via the relay connection portion 19b provided on the upper surface of the base 10 and the printed wiring 19a.

The first thin plate beam portion 22 has a substantially T-shaped notch portion 26 provided at the center of the opposite sides of the silicon wafer.
a and a slit 26b continuous to this are cut out,
It supports the movable electrode 23. The first thin plate beam portion 22 is configured to extend outward from the upper surface edge portion of the anchor 21. For this reason, even if the first and second thin plate beam portions 22 and 24 and the movable electrode 23 are expanded by being heated from the outside, these can freely expand outward, and thus thermal stress and thermal strain are unlikely to occur.

The second thin plate beam portion 24 has a pair of substantially T-shaped notches 2 provided at the centers of opposite sides of the silicon wafer.
It is cut out at 6a and 26a. This second thin plate beam portion 2
4 is a movable contact 28 in the center of the lower surface of the movable contact 28 with an insulating film 27 interposed.
Is provided. The movable contact 28 opposes the fixed contacts 13 and 14 so that the movable contact 28 can contact and separate.

Next, a method of manufacturing the electrostatic micro relay having the above-mentioned structure will be described with reference to the accompanying drawings of FIGS. 2 (a) to 4 (d). First, the fixed electrodes 12 and 12, the fixed contacts 13 and 14, and the relay connection portion 19b are formed on the 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 wirings 16a, 17a, 18a, 19a continuous to the relay connection portion 19b, respectively,
The connection pads 16, 17, 18, and 19b are formed (FIG. 2B). Then, an insulating film (not shown) is formed on the fixed electrode 12 to complete the base 10. If a silicon oxide film having a relative permittivity of 3 to 4 or a silicon nitride film having a relative permittivity of 7 to 8 is used as the insulating film, a large electrostatic attractive force can be obtained and a 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 wet etching by TMAH using, for example, a silicon oxide film as a mask is performed. As a result, four anchors 21 are formed and a step portion 21a is formed on the lower end surface of the one anchor 21 (FIG. 3B). Then, after forming the insulating film 27 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 mounted on the base 10.
0 is integrated by anodic bonding (FIG. 4A). Then, the upper surface of the SOI wafer 30 is thinned by etching the oxide film 31 with an alkali etching solution such as TMAH or KOH (FIG. 4B). Further, the oxide film 31 is removed with a fluorine-based etching solution 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, notches 26a and slits 26b are formed to cut out the first and second thin plate beam portions 22 and 24, and unnecessary silicon wafers are removed (FIG. 4 (d)).
The actuator 20 is completed.

According to this embodiment, the actuator 20
The whole is formed of a single silicon wafer, and is formed symmetrically with respect to the left and right sides and the section. Therefore, the movable electrode 25
Less likely to warp or twist. As a result, it is possible to effectively prevent the inoperability and the variation in the operation characteristics, and it is possible to ensure the smooth operation characteristics.

Next, the operation of the electrostatic micro relay having the above-mentioned structure will be described. First, when no voltage is applied between the fixed electrode 12 and the movable electrode 23, the fixed electrode 12
And the movable electrode 23 are kept parallel to each other, 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 the electrostatic attractive force generated between the electrodes 12 and 23. Therefore, 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 a 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 adsorbed to the fixed electrode 12 via an insulating film (not shown).

When the application of the voltage is stopped, the movable contact 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 fixed. The movable electrode 23 returns to its original state after being separated from 14.

In the electrostatic micro relay according to the second embodiment, as shown in FIG. 5, the actuator 20 is supported by two anchors 21 provided upright on the upper surface of the base 10.

The base 10 has a pair of fixed electrodes 12 and 12 arranged in parallel on the upper surface of a glass substrate 11 at a predetermined interval, and a pair of fixed contacts 13 and 14 between them. The surfaces of the fixed electrodes 12 and 12 are covered with an insulating film (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 and 14 and the relay connection portion 19b are connected to the printed wirings 16a, 17a, 18a and 19 respectively.
It is connected to the connection pads 16, 17, 18, and 19 via a, respectively.

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

The anchor 21 is connected to the printed wiring 17
It is arranged at a position facing each other with a and 18a in between.
Particularly, of the two anchors 21, a step portion 21 a is formed on one half of the lower end surface of one anchor 21. The step portion 21 a is a relay connection portion 19 provided on the upper surface of the base 10.
It is connected to the connection pad 19 via b and the printed wiring 19a.

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.
It is cut out by a slit 26b continuous with this and supports the movable electrode 23. The first thin plate beam portion 22 is
It is configured to extend outward from the upper edge of the anchor 21. Therefore, the first thin plate beam portion 22 is heated from the outside.
Further, even if the movable electrode 23 expands, these can freely expand outward, and thus thermal stress and thermal strain are unlikely to 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 opposes the fixed contacts 13 and 14 so that the movable contact 28 can contact and separate. The second
The manufacturing method and operation of the electrostatic micro relay according to the embodiment are almost the same as those of the first embodiment described above, and thus the description thereof will be omitted.

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

In the electrostatic micro relay according to the third embodiment, as shown in FIG. 6, the actuator 20 is supported by one anchor 21 standing on the upper surface of the base 10. That is, the base 10 is the glass substrate 1
A fixed electrode 12 is provided on the upper surface of 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 the actuator 20 is provided near the fixed contacts 13 and 14.
Is provided. Further, the fixed electrode 12, the fixed contacts 13 and 14 and the relay connection portion 19b are connected to the connection pad 1 through the printed wirings 16a, 17a, 18a and 19a.
6, 17, 18, and 19, respectively.

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

The anchor 21 has a stepped portion 21a formed on one side half of the lower end surface thereof. 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 obtained by cutting a silicon wafer by providing a through hole 26d in the vicinity of one side edge portion. In the present embodiment, the first thin plate beam portions 22 and 22 extend outward from the upper edge portion of the anchor 21, and the movable electrode 23 also extends from the first thin plate beam portions 22 and 22. Therefore, even if the first thin plate beam portion 22 and the movable electrode 23 are expanded by being heated, they can be expanded outward freely, and thermal stress and thermal strain are unlikely to occur.

A movable contact 28 is provided in the center of the lower surface of the second thin plate beam portion 24 with an insulating film 27 interposed therebetween. The movable contact 28 opposes the fixed contacts 13 and 14 so that the movable contact 28 can come into contact with and separate from the fixed contacts 13 and 14.

Since the manufacturing method and operation of the electrostatic micro relay according to the third embodiment are almost the same as those of the first embodiment, the description thereof will be omitted.

[0037]

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

According to the second aspect, the thin plate beam portion is laterally extended from the upper end edge of one anchor erected on the base, and the movable electrode is connected to and supported by the thin plate beam portion. . Therefore, even if the base and the actuator, which have a large difference in thermal expansion coefficient, are joined and integrated in an expanded state and then returned to room temperature, thermal stress and thermal strain unlike the conventional example do not occur in the actuator. As a result, the actuator is not deformed, and operating characteristics as designed are obtained in drive voltage, contact load, operating speed, and the like.

According to the second and third aspects, the movable electrode is
The anchor is connected to and supported by the free end of a thin plate beam portion extending outward from the upper edge of the anchor. Therefore, even if the actuator is heated to join and integrate it with the base, the actuator can freely expand outward. As a result, the actuator itself is not subjected to thermal stress and thermal strain, and the actuator is not deformed. Therefore, the operating characteristics as designed are further obtained in terms of driving voltage, contact load, operating speed and the like.

If the fixed contact is arranged near the base of the anchor, the movable contact that contacts the fixed contact will be located nearer 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 due to the principle of leverage, so that malfunction does not occur due to vibration or the like from the outside. In particular, if the thin plate beam portion is extended from four anchors arranged near the four sides of the fixed contact, the movable contact comes into contact with the fixed contact with the contact load applied from the four sides, so that malfunction does not occur further.

A silicon actuator may be integrated with the glass base by anodic bonding to form the above-mentioned structure. According to this, there is an effect that it is possible to obtain an electrostatic micro-relay having operating characteristics as designed in terms of driving voltage, contact load, operating speed, and the like.

[Brief description of drawings]

1 shows an electrostatic micro relay according to a first embodiment of the present invention, FIG. 1 (a) is a plan view, FIG. 1 (b) is a sectional view taken along line 1B-1B of FIG. 1 (a), Figure 1 (c) is
It is a 1C-1C line sectional view 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.

FIG. 6 shows an electrostatic micro relay according to a third embodiment of the present invention, FIG. 6 (a) is a plan view, and FIG. 6 (b) is a sectional view taken along line 6B-6B of FIG. 6 (a).

[Explanation of symbols]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-112032 (JP, A) JP-A-2-100224 (JP, A) JP-A-57-197728 (JP, A) JP-A-8- 227647 (JP, A) JP 11-111146 (JP, A) JP 9-92116 (JP, A) JP 11-54013 (JP, A) JP 5-2976 (JP, A) JP 5-2973 (JP, A) JP 5-2972 (JP, A) JP 6-267383 (JP, A) Actual development JP 3-53731 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01H 59/00

Claims (3)

(57) [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, and the movable electrode is moved to the base. In an electrostatic micro relay that opens and closes an electric circuit by moving a movable contact provided on the actuator to and from a fixed contact provided on the base, a plurality of anchors are concentrated and erected at one place on the upper surface of the base. An electrostatic micro relay, wherein the movable electrode is supported via a thin plate beam portion that extends laterally from the upper edge of the. 2. The movable electrode is driven by an electrostatic attraction generated by applying a voltage between a fixed electrode provided on the upper surface of the base and a movable electrode of an actuator fixed on the upper surface of the base, and the movable electrode is moved to the base. In an electrostatic micro relay that opens and closes an electric circuit by bringing a movable contact provided in the actuator into contact with and separated from a provided fixed contact, a side from an upper edge of one anchor standing on the upper surface of the base, and The movable electrode of the actuator is connected to the free end of at least one thin plate beam portion extending outward,
An electrostatic micro relay characterized by being supported. 3. The electrostatic micro relay according to claim 1, wherein the movable electrode is connected to and supported by a free end of a thin plate beam portion extending outward from an upper edge portion of the anchor.