JP2002289081A - Electrostatic microrelay and radio device and measuring device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the suitable contact separation force excellent in a high frequency characteristic with a simple and small-size structure that can be easily manufactured with low cost. SOLUTION: Signal lines 5a, 5b formed on a fixed substrate 1 are arranged on the same line. A movable substrate 2 is elastically supported on the fixed substrate 1 through a beam part 11 arranged in two places of point symmetry positions by using a movable contact 16 as a center point. The part facing to the signal lines 5a, 5b is removed from the movable substrate 2. The movable contact is elastically supported on two places orthogonal to the line where the signal lines 5a, 5b are arranged as well as not facing to the signal lines 5a, 5b. A pair of projections 17 are formed in point symmetry to the movable contact 16 as a center on a position attaching to either of the substrates 1, 2 that faces first.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic microrelay that opens and closes a signal line by being driven based on an electrostatic attraction generated between electrodes, a radio device using the electrostatic microrelay, and a radio device using the electrostatic microrelay. It relates to a measuring device.

[0002]

2. Description of the Related Art Conventionally, as an electrostatic micro relay, for example, there are those disclosed in JP-A-2000-164104 and JP-A-2000-113792.

[0003] In the former, a movable contact is closed to a fixed contact by applying a voltage between the electrodes to generate an electrostatic attraction and drive the movable substrate, and the signal lines arranged on the fixed substrate are mutually connected. Make an electrical connection. Slits are formed on both sides of the movable contact on the movable substrate, and projections are formed at four locations on the lower surface, thereby increasing the contact separating force.

In the latter, a movable substrate is elastically supported at two positions on a fixed substrate, signal lines are provided on the fixed substrate on the same straight line, and fixed electrodes disposed on both sides thereof are also used as high-frequency GND electrodes. .

[0005]

However, the former is not suitable for opening and closing high-frequency signals because the signal lines are arranged in parallel. The protrusion contacts the opposing substrate before closing the contact, but its position is not the most suitable position for improving the operation characteristics.

On the other hand, the latter is suitable for opening and closing high-frequency signals, but does not take into account the configuration of a convex portion or the like for increasing the contact separating force. It is difficult to obtain desired operating characteristics by simply adopting the former convex portion, since an optimal position for providing the convex portion is not specified.

Therefore, the present invention provides an electrostatic microrelay that has a simple and small structure that can be easily manufactured at low cost and that can obtain an appropriate contact separating force, and a radio using the electrostatic microrelay. It is an object to provide a device and a measuring device.

[0008]

According to the present invention, there is provided, as a means for solving the above-mentioned problems, a method which is performed between a fixed electrode of a fixed substrate and a movable electrode of a movable substrate supported on the fixed substrate via a beam. By driving the movable substrate based on the electrostatic attraction to be applied, by moving the movable contact formed through the insulating film on the movable substrate to the fixed contact provided on each of the two signal lines formed on the fixed substrate, In the electrostatic microrelay configured to electrically open and close the signal line, the beam portion elastically supports the movable substrate at two point-symmetric positions around the movable contact, and the signal line is The fixed contacts on one end are arranged on the same straight line on the fixed substrate so as to be adjacent to each other at a predetermined interval, and the movable substrate has at least a portion facing a signal line removed, and Directly on the straight line where the signal line is And elastically supported at two places not opposed to the signal line, and a pair of convex portions are provided on one of the substrates at a portion that first comes into contact with the opposed substrate after the contact is closed. Are formed point-symmetrically with respect to the center.

With this configuration, the contact opening force can be switched in two stages in accordance with the change in the electrostatic attraction, although the structure is suitable for opening and closing high-frequency signals. That is, in the range where the electrostatic attraction is weak, the convex portion does not come into contact with the opposing substrate, and the movable substrate is easily deformed according to the electrostatic attraction. Then, in a range where the electrostatic attraction is strong, the elastic force of the movable substrate is increased by the projections abutting on the opposing substrate. In addition, the projection is provided at a portion that first comes into contact with the opposing substrate after the contact is closed. Therefore, the elastic force on the movable contact side of the movable substrate can be changed at the position most suitable for the electrostatic attractive force curve, and the contact opening property can be improved.

[0010] After the convex portion contacts one of the substrates, the convex portion abuts on the opposing substrate. Then, the convex portion abuts on the opposing substrate. Since the elastic force on the movable contact side increases and can follow the electrostatic attraction curve, it is preferable in that an appropriate contact opening force can be obtained.

The projection may be made of an insulating material.

When the electrode is removed from at least the portion of the substrate at which the convex portion comes into contact with / separates from the convex portion, an organic substance or the like does not adhere between the convex portion and the electrode facing the convex portion. This is preferable in that the operating characteristics described above can be obtained.

Incidentally, the electrostatic microrelay having the above-mentioned structure is
It is suitable for opening and closing contacts in devices that handle high-frequency signals, such as wireless devices and measuring devices.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show an electrostatic micro relay according to the present embodiment. The electrostatic micro relay MR has a configuration in which a movable substrate 2 is provided on an upper surface of a fixed substrate 1.

The fixed substrate 1 has a fixed electrode 4 and signal lines 5a and 5b formed on an upper surface of a glass substrate 3. The surface of the fixed electrode 4 is covered with an insulating film 6. Signal line 5
a and 5b are arranged on the same straight line, and have fixed contacts 7a and 7b adjacent to the center of the glass substrate 3 at a predetermined interval. The signal lines 5a and 5b are connected to the connection pads 8a and 8b, respectively. A connection pad 8c is formed on the side of the signal line 5b via a wiring pattern 9a. The movable electrode 12 of the movable substrate 2 is electrically connected to the wiring pattern 9a and the connection pad 8c. Fixed electrode 4
Are formed with connection pads 8d for voltage application and connection pads 8e to be connected to GND. Connection pad 8e
Plays a role of preventing signal leakage when transmitting high-frequency signals through the signal lines 5a and 5b.

As shown in FIG. 3, the movable substrate 2 is provided with a movable electrode 12 uniformly on two first beam portions 11 extending laterally from a support portion 10 erected on the upper surface of the fixed substrate 1. This is what we support. The movable electrode 12 includes the first beam portion 11, the support portion 10, and the printed wiring 9 provided on the upper surface of the fixed substrate 1.
a, and is electrically connected to the connection pad 8c. A contact base 14 is elastically supported by a pair of second beams 13 at the center of the movable electrode 12. On the lower surface of the contact stand 14,
A movable contact 16 is provided via an insulating film 15. The movable contact 16 is brought into contact with and separated from the fixed contact 7 and the signal line 5a,
Open and close 5b. On the lower surface of the movable electrode 12, projections 17 are respectively formed at positions symmetrical with respect to the point around the movable contact 16, more specifically, at positions where the movable electrode 12 first contacts the fixed electrode 4 after the contact is closed. ing. As a result, when the movable substrate 2 bends due to the electrostatic attraction, before the contact is closed,
The projection 17 always comes into contact with the fixed substrate 1. Then, the separation force after contact and the rate of decrease in contact force associated therewith become an ideal state. The projection 17 is formed such that the distance between the movable electrode 12 and the fixed electrode 4 at the time of contact with the fixed substrate 1 is equal to or less than １ ／ of the distance between the fixed substrate 1 and the movable substrate 2 that are separated. I have. Thereby, at the time when the convex portion 17 comes into contact with the fixed substrate 1, the electrostatic attraction suddenly increases, and the convex portion 17
Irrespective of the presence of, the movable electrode 12 can be surely adsorbed to the fixed electrode 4.

Incidentally, the convex portion 17 is closer to the fixed electrode 4 facing the other portion (movable electrode 12). For this reason, the electrostatic attraction increases and the electric field concentrates. If there is a foreign substance such as an organic substance in the surroundings, the foreign substance is attracted to and adheres to the convex portion 17 where the electric field is concentrated. In this case, there is a possibility that the operating characteristics become unstable due to a change in the height of the convex portion 17. Therefore, as shown in FIG.
A non-electrode portion 18 from which the fixed electrode 4 is removed is formed in a portion facing the projection 17. However, if the convex portion 17 is formed of an insulator, for example, an oxide film, the generated electrostatic attraction is suppressed, and thus the non-electrode portion 18 is not necessarily required. Further, when the convex portion 17 is formed in, for example, a semi-cylindrical shape, the electric field concentration can be suppressed, and a structure in which a foreign substance is not easily attracted can be obtained.

Subsequently, the electrostatic micro relay M having the above configuration
A method for manufacturing R will be described.

First, as shown in FIG. 4B, a fixed electrode 4 and fixed contacts 7a and 7b (only 7a is shown) are placed on a glass substrate 3 such as Pyrex (registered trademark) shown in FIG. Form. At the same time, printed wiring 9a, connection pads 8a, etc., not shown in FIG. 4 are formed. And
By forming an insulating film 6 on the fixed electrode 4, FIG.
The fixed substrate 1 shown in (c) is completed. If a silicon oxide film having a relative dielectric constant of 3 to 6 or a silicon nitride film having a relative dielectric constant of 7 to 8 is used as the insulating film 6, a large electrostatic attraction can be obtained and the contact force can be increased.

On the other hand, as shown in FIG. 4D, 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 using TMAH using the oxide film as a mask, as shown in FIG. 4E, a support portion 10 and a convex portion 17 protruding downward are formed. Then, as shown in FIG. 4F, after the insulating film 15 is provided, the movable contact 16 is formed.

Next, as shown in FIG. 4 (g), the SOI wafer 100 is bonded and integrated to the fixed substrate 1 by anodic bonding. Then, as shown in FIG. 4H, the upper surface of the SOI wafer 100 is etched down to a silicon oxide layer 102 as 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 103, that is, the movable electrode 12, as shown in FIG. Then, die cutting etching is performed by dry etching using RIE or the like, and the first and second beam portions 11 and 13 are cut out to complete the movable substrate 2. Note that the fixed substrate 1 is not limited to the glass substrate 3 and may be formed of a single crystal silicon substrate having at least an upper surface covered with an insulating film 6.

Next, the electrostatic micro relay MR having the above configuration
Will be described with reference to the schematic diagram of FIG.

In a state where no voltage is applied between the two electrodes and no electrostatic attraction is generated, the first beam portion 11 is not elastically deformed as shown in FIG. The movable substrate 2 faces the fixed substrate 1 at a predetermined interval. Therefore, the movable contact 16 is separated from the fixed contacts 7a and 7b.

Here, when a voltage is applied between the two electrodes to generate an electrostatic attraction, the first beam portion 11 is elastically deformed, and the movable substrate 2 approaches the fixed substrate 1. As a result, FIG.
As shown in (1), the convex portion 17 contacts the fixed substrate 1. As shown in FIG. 6, the electrostatic attraction tends to increase as the distance between the electrodes decreases. When the protrusion 17 approaches the fixed substrate 1 until it comes into contact with the fixed substrate 1, the electrostatic attraction acting between the electrodes 4 and 12 is set to increase sharply. Accordingly, the movable electrode 12 is attracted to the fixed electrode 4 by partially elastically deforming the periphery of the convex portion 17 of the movable substrate 2. As a result, the movable contact 16 closes to the fixed contact 7 as shown in FIG. After the movable contact 16 comes into contact with the fixed contact 7, as shown in FIG. 5D, the second beam 13 bends in addition to the first beam 11, and the movable electrode 12 contacts the fixed electrode 4. Adsorbed. Therefore, the movable contact 16 is pressed against the fixed contact 7 via the second beam 13 by the surrounding movable electrode 12 being attracted to the fixed electrode 4. Therefore, there is no one-side contact, and the contact reliability is improved.

At this time, the first and second beam portions 11 and 13 apply a force for pulling the movable electrode 12 upward Fs1 and Fs2, and the convex portion 17 comes into contact with the fixed substrate 1 until the contact portion closes. The force that pulls the movable electrode 12 upward due to elastic deformation around the part is Fs
3. If the electrostatic attractive force between the movable electrode 12 and the fixed electrode 4 via the insulating film 6 is Fe, and the drag force from the surface of the insulating film 6 is Fn, there is the following relationship (Equation 1). 2nd beam part 11, 1
By designing the spring coefficient of 3, the initial gap between the movable electrode 12 and the fixed electrode 4, the thickness of the contact, etc., Fn and Fs1 are reduced, and Fs2, that is, the contact force (from the ideal model)
It is possible to suppress the decrease.

[0026]

[Equation 1] Fe = Fs1 + Fs2 + Fs3 + Fn

Thereafter, when the voltage applied between the two electrodes is removed, not only the elastic force of the first and second beam portions 11 and 13 but also the elastic force due to deformation near the convex portion 17 acts as a contact separating force. Can be done. Therefore, even if adhesion or welding occurs between the contacts, the contacts can be reliably separated. After the contact is separated, the movable substrate 2 returns to its original position by the elastic force of the first beam portion 11 after the convex portion 17 is separated by the elastic force around the convex portion 17 until the convex portion 17 is separated. I do.

As described above, in the above embodiment, the protrusion 17
Is formed, the contact separating force can be greatly increased, and the operation of the movable substrate 2 when removing the applied voltage can be performed smoothly.

Further, the entire movable substrate 2 is formed of a single silicon wafer, and is formed so as to be symmetric with respect to right and left points and symmetrical in cross section. Therefore, the movable electrode 12 is unlikely to be warped or twisted. Therefore, inoperability and variation in operating characteristics can be effectively prevented, and smooth operating characteristics can be ensured.

Since the electrostatic microrelay MR having the above-described configuration has a characteristic of transmitting a DC signal to a high-frequency signal with low loss and good transmission, for example, the wireless device 110 shown in FIG. 7 and the measuring device 120 shown in FIG. It is possible to adopt. In FIG. 7, the electrostatic micro relay MR has an internal circuit 1
12 and an antenna 113. In FIG. 8, the electrostatic micro relay MR is connected in the middle of each signal line from the internal circuit 121 to the object to be measured (not shown). According to this, it is possible to transmit a signal more accurately while suppressing a load on an amplifier or the like used in an internal circuit as compared with a conventional element. In addition, it is small in size and consumes little power, and is particularly effective in a battery-powered wireless device and a plurality of measuring devices used.

In the above embodiment, the movable substrate 2 is
Although the first beam portion 11 of the book is supported, it may be supported by three or four beam portions. This makes it possible to obtain an electrostatic microrelay with high area efficiency. Specifically, a configuration in which the movable substrate 2 is supported by four beams is shown in FIG. 9 has the same configuration as that of FIG. 1 except that four beams 11 are provided.

Further, the electrostatic micro relay MR may be configured as shown in FIG. That is, in this electrostatic micro relay, the support portion 31 is configured by a rectangular frame provided on the upper surface of the fixed substrate 30. The movable substrate 40 is cantilevered from the inner edge of the support portion 31 to the connecting portion 32.
An insulating film 41 is formed on the lower surface of the movable substrate 40, and a movable contact 42 is provided on a free end side thereof. A convex portion 43 is formed between the movable contact 42 and the connecting portion 32, and the fixed substrate 30 is closed before the movable contact 42 is closed to the fixed contact 33.
To come into contact with. If the convex portion 43 is provided at a position where the movable substrate 40 first comes into contact with the fixed substrate 30 after the contact is closed, the contact force can be maximized. When the projection 43 is further provided, it is preferable that the projection is provided at a position where the movable substrate 40 comes into contact with the fixed substrate 30 next.

In the above-described embodiment, the movable electrode 12 has a flat shape. However, a concave portion may be formed on the upper surface to make the movable electrode 12 thin. Thereby, it is possible to further improve the operation and the return speed even if it is lightweight, while securing desired rigidity. Moreover, the rigidity may be increased by making the movable electrode 12 thicker than the beam portion. Thereby, all of the electrostatic attraction can be used as the attraction to the movable electrode 12, and the electrostatic attraction can be efficiently used for deformation of the first beam portion 11 or the second beam portion 13.

In the above-described embodiment, the convex portion 17 is provided on the movable substrate 2, but may be provided on the fixed substrate 1 or both substrates. Further, two or more pairs of the convex portions 17 may be provided between the contact point and the support portion 10. In this case, after the convex portion 17 first comes into contact with the fixed substrate 1, the next convex portion 17 may be sequentially provided at a position where the movable substrate 2 comes into contact with the fixed substrate 1. This makes it possible to further stabilize the contact force and the separating force as compared with the case where only one pair of the protrusions 17 is provided.

[0035]

As is apparent from the above description, according to the present invention, the structure can be easily manufactured at low cost by a semiconductor process, and the structure is simple and small. Further, since the signal lines are arranged on the same straight line and the opposing movable substrates are removed, excellent high-frequency characteristics are exhibited. Further, since the convex portion is formed on at least one of the two substrates, a desired uniform contact contact force can be obtained and the contact opening force can be increased when the contacts are closed. In particular, since the convex portion is formed at a portion that first comes into contact with the opposing substrate after the contact is closed, it is possible to exert an optimal contact separating force with respect to an electrostatic attraction curve when the contact is opened. It becomes possible.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view of an electrostatic micro relay according to a first embodiment.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a perspective view showing a state in which the movable substrate shown in FIG. 2 is viewed from the opposite side.

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

FIG. 5 is a schematic diagram showing an operation state of the electrostatic micro relay shown in FIG.

FIG. 6 is a graph showing a relationship between a gap size between a fixed substrate and a movable substrate, an electrostatic attractive force, and an elastic force of the movable substrate.

FIG. 7 is a block diagram showing a state where the electrostatic micro relay of FIG. 1 is employed in a wireless device.

8 is a block diagram showing a state in which the electrostatic micro relay of FIG. 1 is employed in a measuring device.

FIG. 9 is a plan view (a) and a sectional view (b) of an electrostatic micro relay according to another embodiment.

FIG. 10 is a plan view (a) and a sectional view (b) of an electrostatic micro relay according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixed board 2 ... Movable board 4 ... Fixed electrode 5a, 5b ... Signal line 6 ... Insulating film 7 ... Fixed contact 10 ... Support part 11 ... 1st beam part 12 ... Movable electrode 13 ... 2nd beam part 16 ... Movable contact 17 ... convex part

Claims (6)

[Claims] The movable substrate is formed on the fixed substrate by driving the movable substrate based on an electrostatic attraction generated between a fixed electrode of the fixed substrate and a movable electrode of the movable substrate supported on the fixed substrate via a beam. An electrostatic micro relay that electrically opens and closes the signal lines by contacting and separating a movable contact formed on the movable substrate via an insulating film with fixed contacts provided on the two signal lines, respectively. The beam portion is located at a point symmetric position 2 about the movable contact.
The movable substrate is elastically supported, and the signal lines are arranged on the same straight line on the fixed substrate so that the fixed contacts at one end are adjacent to each other at a predetermined interval. The portion facing the line is removed, and the movable contact is elastically supported at two points that are orthogonal to the straight line on which the signal line is provided, and that do not face the signal line, and on one of the substrates, An electrostatic microrelay, wherein a pair of convex portions are formed point-symmetrically with respect to the movable contact at a portion which first comes into contact with the opposing substrate after the contact is closed. 2. The method according to claim 1, wherein after one of the substrates has the convex portion in contact with the opposing substrate, the convex portion is sequentially disposed in a portion in contact with the opposing substrate. Electrostatic micro relay. 3. The electrostatic micro relay according to claim 1, wherein the projection is made of an insulating material. 4. The electrostatic microrelay according to claim 1, wherein an electrode is removed from at least a portion of the substrate at which the protrusion contacts and separates. 5. A wireless device, wherein the electrostatic micro relay according to claim 1 is provided so as to open and close an electric signal between an antenna and an internal circuit. 6. A measuring apparatus, wherein the electrostatic micro relay according to claim 1 is provided so as to open and close an electric signal between an object to be measured and an internal circuit.