JPH10154456A - Micro-relay, manufacture and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the driving voltage and increase the withstand pressure by forming the upper face of a base cantilever, supporting a moving contact piece contacted to or separated from driving electrodes into a slant face, so that the facing distance is increased from the base section of the moving contact piece toward the free end. SOLUTION: Drive electrodes 19, 20 are provided in parallel outside printed wires 15, 16 connected to fixed contact points 13, 14, provided below an insulating film-covered slant face 12 formed on one side on a base 10 such as a single- crystal silicon substrate. A springy moving contact piece 30, cantilever-supported on the base 10 is preferably made of a single-crystal silicon material having a nearly U-shaped plane, and a moving contact point 31 made of a thin metal film is formed at the center of the lower face via an insulating film. The slant face 12 is preferably formed into a curved face or a taper face, and the contact separation is set to 30-50μm. The moving contact piece 30 is deformed by the applied voltage between the electrodes 19, 20, conduction is finally attained by the contact between the fixed contact points 13, 14 and the moving contact point 31, and since a base section is initially abutted against the slant face 12 having a short distance, low voltage is sufficient for the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microrelay, and more particularly to a drive mechanism for a movable contact piece utilizing electrostatic attraction.

[0002]

2. Description of the Related Art Conventionally, as a micro relay, an electromagnetic type using electromagnetic force as a driving source, a thermal type using thermal expansion,
An electrostatic type using electrostatic attraction as a driving source has been proposed. In the electromagnetic type, not only is it difficult to reduce the size of the magnetic material parts and coils, but also the magnetic force is significantly reduced as the size is reduced, so that an efficient type cannot be obtained. Also,
Since it is not easy to rapidly cool the movable contact piece in the thermal type, it is difficult to speed up the opening and closing operation. further,
Since the thermal expansion and contraction are repeated, the movable contact piece is easily fatigued and has low reliability. On the other hand, the electrostatic type is not only low in power consumption but also simple in structure and excellent in responsiveness.

[0003]

However, in the conventional method using electrostatic attraction as a driving source, a high driving voltage of several hundred volts is required to obtain a desired contact pressure. On the other hand, to lower the drive voltage, the movable contact piece must be brought closer to the drive electrode. For this reason, a desired inter-contact distance cannot be secured, and the withstand voltage is low. As a result, there is a problem that desired contact pressure and withstand voltage cannot be simultaneously secured.

[0004] In view of the above problems, an object of the present invention is to provide an electrostatic microrelay having a low driving voltage and a high withstand voltage.

[0005]

In order to achieve the above object, a micro relay according to the present invention has a movable contact provided on a lower surface of a free end portion of a movable contact piece cantilevered on an upper surface of a base while a movable contact is provided on the lower surface of the base. In a microrelay provided on a top surface with a pair of fixed contacts that are detachably opposed to the movable contact and a drive electrode that is detachably opposed to the movable contact piece, the upper surface of the base is placed on the movable contact piece. The distance between the movable contact piece and the movable contact piece increases from the base to the free end.

[0006] The inclined surface of the base may be a curved surface or a tapered surface. Further, the movable contact piece may be substantially U-shaped in plan view.

[0007] The movable contact piece may be formed of a single crystal silicon material. Further, the movable contact piece may be driven in a reduced-pressure sealed space.

Further, in the micro relay having a fixed contact provided on the inclined surface of the base, the upper surface of the single-crystal silicon substrate is stepped by a plurality of etching processes, and then the step is eliminated by isotropic etching to remove the step. Alternatively, a smooth inclined surface may be formed.

In a micro relay that opens and closes a contact by driving a movable contact piece in a thickness direction by electrostatic attraction,
It is preferable that the driving voltage of the movable contact piece has a frequency equal to or lower than the natural frequency of the movable contact piece.

[0010]

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 and 2, the micro relay according to the first embodiment has a movable contact piece 30 supported on a base 10 in a cantilever manner.

The base 10 is made of a single-crystal silicon substrate 11, and has an inclined surface 12 formed on one side of the upper surface. Near the lower edge of the inclined surface 12, a pair of fixed contacts 13 and 14 are arranged side by side.
They are connected to input / output external connection terminals 17 and 18 through 5 and 16, respectively. Further, the printed wiring 1
A pair of drive electrodes 19, 20 arranged side by side outside 5, 16 are connected to a drive external connection terminal 22 via a printed wiring 21 so as to have the same potential. In addition, the inclined surface 12 of the base 10 does not necessarily need to be a curved surface, and may be a simple taper surface. In addition, the step between the inclined surfaces 12 is, for example, 30 to 50 in consideration of the withstand voltage.
It is preferable that the diameter be set to microns.

The method of manufacturing the base 10 is as follows.
For example, as shown in FIGS. 2A to 2E, an etching mask 23 is appropriately formed on the upper surface of the single-crystal silicon substrate 11, and the etching process is repeated a plurality of times to form a multi-step etching. After the application, there is a method of forming the inclined surface 12 by performing a silicon isotropic etching to eliminate the step on the stepped surface with a solution such as fluorine and smooth the silicon. After covering the inclined surface 12 with an insulating film, the base 10 is completed by patterning the fixed contacts 13 and 14 and the drive electrodes 19 and 20 on the surface of the insulating film. In addition, when the base 10 is a glass material, the above-mentioned insulating film is unnecessary.

The movable contact piece 30 has a substantially U-shaped plane, and a movable contact 31 made of a thin metal film such as gold or aluminum is formed at the center of the lower surface of the movable contact piece 30 via an insulating film. Further, the movable contact piece 30 has both ends joined and integrated with the lower surface of a fixed base 32 having a substantially trapezoidal cross section. The movable contact piece 30 is preferably made of a homogeneous material in order to prevent deformation, warping, and the like after processing. For example, a single crystal silicon substrate or a polysilicon substrate is suitable. By fixing the movable base 32 on the upper surface of the base 10, the movable contact 31 is opposed to the fixed contacts 13 and 14 so as to be able to contact and separate, and the movable contact piece 30 is connected to the driving external connection terminal 24. .

Next, the operation of the contact mechanism having the above configuration will be described. First, when a voltage is applied between the drive electrodes 19 and 20 and the movable contact piece 30, an electrostatic attraction is generated between the two, and the movable contact piece 30 is drawn to the base 10 side. At this time, since the electrostatic attractive force is inversely proportional to the square of the distance, the closer the distance between the two, the more the electrostatic attractive force increases. Therefore, the largest electrostatic attraction acts on the base of the movable contact piece 30 where the distance between the movable contact piece 30 and the inclined surface 12 is the smallest. As a result, in the initial stage, the base of the movable contact piece 30 first contacts the inclined surface 12 (FIG. 1C). Thereafter, the movable contact piece 30 is deformed so as to gradually reduce the distance between the movable contact piece 30 and the inclined surface 12.
Contact the fixed contacts 13 and 14, and the fixed contacts 13 and 14 conduct.

The movable contact piece 30 and the drive electrode 19,
When the voltage applied to the movable contact piece 20 is released, the movable contact piece 30 returns to the original state by the spring force of the movable contact piece 30 itself, and the movable contact 31 is separated from the fixed contacts 13 and 14.

In the second embodiment, as shown in FIG. 3, a pair of fixed contacts 13 and 14 are arranged on the inclined surface 12 side by side.
These are printed wiring lines 1 arranged side by side at predetermined intervals.
They are connected to input / output external connection terminals 17 and 18 via the terminals 5 and 16. Further, a driving electrode 19 is provided between the printed wirings 15 and 16, and a driving external connection terminal 22 is provided.
It is connected to the. On the other hand, the movable contact piece 30 has a straight band shape, and one end of the movable contact piece 30 is cantilevered on the upper surface of the base 10 via the fixed base 32. Further, a movable contact 31 provided on the lower surface of the free end of the movable contact piece 30 is opposed to the fixed contacts 13 and 14 so as to be able to contact and separate therefrom.

When a voltage is applied between the drive electrode 19 and the movable contact piece 30, an electrostatic attraction is generated between them and
The movable contact piece 30 is drawn to the base 10 side. At this time, similarly to the first embodiment, the movable contact piece 30 is
It is adsorbed on the inclined surface 12 from its base. Thereafter, the movable contact piece 30 is sequentially deformed so as to reduce the distance from the inclined surface 12, and finally, the movable contact 31 comes into contact with the fixed contacts 13 and 14, and the fixed contacts 13 and 14 become conductive.

When the applied voltage is released, the movable contact piece 30 returns to its original state by the spring force of the movable contact piece 30 itself, and the movable contact 31 is separated from the fixed contacts 13 and 14.

The movable contact piece 30 includes a movable base 32
The etching mask 34 is formed on the edge of the upper surface of the silicon substrate 33 and is subjected to anisotropic etching as shown in FIGS. 4 (a) to 4 (c). Thus, the base may be formed integrally with the fixed base 35.

In the above-described embodiment, the case of normal pressure has been described. However, in order to reduce air resistance, the movable contact piece may be driven in a reduced-pressure sealed container. However,
When the pressure in the sealed container is reduced to a predetermined pressure, the vibration of the movable contact piece can be effectively attenuated by utilizing air resistance. For this reason, there is an advantage that a microrelay that can respond at high speed and can be applied to a wider frequency range can be obtained.

The frequency of the drive voltage for driving the movable contact piece is preferably a drive voltage having a frequency component equal to or lower than the natural frequency of the movable contact piece. This is because chattering due to resonance of the movable contact piece can be prevented, and agile operation characteristics can be obtained.

Further, in the above-described embodiment, the case where the movable contact piece is straight is described. However, the present invention is not limited to this. The movable contact piece is curved upward, while the upper surface of the base opposed thereto is smooth in a horizontal plane. It may be.

The microrelays described above may be used alone, or a plurality of microrelays may be arranged on one substrate.

[0024]

As is apparent from the above description, according to the micro relay according to the first aspect of the present invention, the movable contact piece starts to be attracted to the inclined surface of the base from the base. For this reason, it can drive with a lower drive voltage than the case where the opposing distance of a movable contact piece and a drive electrode is equal. Furthermore, since the distance between the fixed contact formed on the upper surface of the base and the movable contact provided on the lower surface of the free end of the movable contact piece is the largest in the distance between them, a desired distance between the contacts is secured. It is easy and the pressure resistance is improved. According to the second and third aspects, since the movable contact piece can be formed straight, the manufacture of the movable contact piece becomes easy. According to the fourth aspect, since the movable contact piece has a substantially U-shaped planar shape, it is difficult to twist, and a micro relay in which the movable contact does not hit the fixed contact is obtained. According to the fifth aspect, since the movable contact piece is formed from the single crystal silicon substrate, a micro relay having uniform operating characteristics without deformation or warpage after processing can be obtained. According to the sixth aspect, since the movable contact piece is driven in the reduced-pressure sealed space, the air resistance is reduced. For this reason, it is possible to drive with a high frequency drive voltage, and the opening and closing operation becomes quick. According to the manufacturing method of the seventh aspect, a desired inclined surface can be manufactured by the technique of the semiconductor manufacturing process. For this reason, many bases having minute and complicated inclined surfaces can be manufactured at a time, and a microrelay with high productivity can be obtained. According to the control method of claim 8,
The frequency of the drive voltage for driving the movable contact piece does not match the natural frequency of the movable contact piece. Therefore, the movable contact piece does not resonate and chattering does not occur, so that a micro relay having agile opening and closing characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a microrelay according to the present invention, wherein FIG. 1 (a) is a plan view and FIGS. 2 (b) to 2 (d) are cross-sectional views showing operating states.

FIG. 2 is a process chart showing a method for manufacturing the base of FIG. 1;

3A and 3B show a second embodiment of a micro relay according to the present invention, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view.

FIG. 4 is a process chart showing a method for manufacturing a movable contact piece.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Base, 11 ... Single crystal silicon substrate, 12 ... Inclined surface, 13, 14 ... Fixed contact, 15, 16 ... Printed wiring, 17, 18 ... Input / output external connection terminal, 19, 20 ...
Drive electrode, 21: printed wiring, 22, 24: external connection terminal for driving, 30: movable contact piece, 31: movable contact, 32
... Fixing base, 33 ... Single-crystal silicon substrate.

Claims (8)

[Claims] A movable contact is provided on a lower surface of a free end of a movable contact piece cantilevered on an upper surface of a base, and a pair of fixed contacts opposed to the movable contact on the upper surface of the base so that the movable contact can be separated from the movable contact. In a microrelay provided with a drive electrode opposing to and detachable from the movable contact piece, an opposing distance from an upper surface of the base to the movable contact piece increases from a base to a free end of the movable contact piece. Characteristic micro relay. 2. The micro relay according to claim 1, wherein the inclined surface of the base is a curved surface. 3. The micro relay according to claim 1, wherein the inclined surface of the base is a tapered surface. 4. The microrelay according to claim 1, wherein the movable contact piece has a substantially U-shaped plane. 5. The micro relay according to claim 1, wherein the movable contact piece is made of a single crystal silicon material. 6. The microrelay according to claim 1, wherein the movable contact piece is driven in a reduced-pressure sealed space. 7. A micro relay having a fixed contact provided on an inclined surface of a base, wherein the upper surface of the single crystal silicon substrate is stepped by a plurality of etching treatments, and then the step is eliminated by isotropic etching. A method for manufacturing a micro relay, wherein a smooth inclined surface is formed. 8. A micro relay for driving a movable contact piece in a thickness direction by electrostatic attraction to open and close a contact, wherein a driving voltage of the movable contact piece is set to a frequency equal to or lower than a natural frequency of the movable contact piece. A method for controlling a micro relay.