JPH0714490A - Electrostatic actuating relay - Google Patents

Abstract

PURPOSE:To prevent the root sections of movable sections from being broken because of stress concentration. CONSTITUTION:A movable piece 2 allows the circumference of a movable electrode 4 to be cut off in an U shape by means of plasma etching such as RIE and the like so as to allow its root sections 30 at both the sides to be formed into a R shape each. The root sections 3O in a R shape prevent stresses from being concentrated at the root sections 30, and the root sections 30 are prevented from being damaged by external impact and vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic drive type relay driven by electrostatic force.

[0002]

2. Description of the Related Art Known examples of conventional electrostatic drive type relays include Japanese Examined Patent Publication (Kokoku) No. 55-15060 and Japanese Patent Laid-Open No. 100224.
22. In this configuration, a fixed electrode 40 is formed on a substrate 42 that constitutes a fixed piece as shown in FIG. 22, and a movable piece 41 is arranged in parallel above the fixed electrode 40. Has become. The movable piece 41 constitutes a movable electrode, is made of a silicon wafer, has a groove 44 formed between the movable electrode 41 and the peripheral portion by anisotropic etching, and a voltage applied between the fixed electrode 40 and the movable electrode. The support end portion 42 integrally connected to the peripheral portion is operated as a fulcrum by the electrostatic force generated by.

[0003]

By the way, the movable piece 4 is used.
The root of the first support end 42 is a corner, so that stress concentration is likely to occur and there is a problem that the root breaks. Further, since the substrate 43 forming the fixed electrode 40 on the movable piece 41 made of a silicon wafer is made of synthetic resin, the coefficient of thermal expansion of the movable piece 41 and the coefficient of thermal expansion of the substrate 43 are different, and as a result, at the time of bonding. When the temperature during use changes, the structure is distorted, and stress concentration is likely to occur at the root of the support end 42 of the movable piece 41.

The invention of claim 1 is to solve the above-mentioned problems, and the purpose thereof is to electrostatically drive the root of the movable part to prevent damage due to stress concentration. To provide relays. In addition to the object of the invention of claim 1, an object of the invention of claim 2 is to provide an electrostatic drive type relay in which contact pressure is improved and matching with a spring load is facilitated.

[0005]

In order to achieve the above object, the invention according to claim 1 has a fixed piece on which a fixed electrode can be formed, and a movable electrode which faces the fixed electrode with a gap therebetween. The movable piece has a movable part whose other end is supported and fixed so that one end moves to the fixed electrode side by an electrostatic force generated by an external voltage applied between the electrode and the movable electrode, and the movable piece is moved. In the electrostatic drive type relay, in which contact points that are brought into contact with and separated from each other by movement of the parts are provided at one end of the movable part and an end of the fixed piece corresponding to the one end, and these contacts are connected to an external electric circuit, The roots on both sides of the other end of the section are spread outward by R processing.

According to a second aspect of the present invention, in the gap between the movable portion and the fixed piece facing the movable portion, a convex portion is formed on either one of the facing surfaces of the movable portion and the fixed piece, and the other is formed. The convex portion forms a concave portion that meshes with a gap.

[0007]

According to the structure of the invention as set forth in claim 1, since both side roots of the other end of the movable portion are spread outward by R processing, stress is applied to both side roots of the other end of the movable portion. Concentration does not occur, so it is not damaged even if there is an impact from the outside. According to the configuration of the invention of claim 2, the convex portion is formed on one of the facing surfaces of the movable portion and the fixed piece, and the concave portion is formed on the other surface so that the convex portion meshes with a gap. The gap between the tip of the part and the inner wall of the recess facing it is very small, so that the electrostatic force acting on the movable electrode can be increased, and as a result, the contact pressure can be made large and the contact of the contact Improved reliability, less likely to malfunction due to external vibrations and shocks, and low applied voltage to the electrodes, especially wide gap between the movable electrode contact and the fixed electrode contact. Therefore, the breakdown voltage between contacts can be increased and the voltage of the drive circuit can be lowered.

[0008]

EXAMPLES The present invention will be described below with reference to examples. (Embodiment 1) This embodiment comprises an upper fixed piece 1, a movable piece 2 and a lower fixed piece 3, as shown in FIGS.
The movable piece 2 is sandwiched between the upper and lower fixed pieces 1 and 3.

As shown in FIG. 3, the movable piece 2 is made of a silicon single crystal wafer as a base material, and has a movable electrode 4, a fixed contact terminal 5, a movable contact 6, a metal thin film layer 7 for joining fixed pieces, and an electrode terminal. 8 etc. are formed. The movable electrode 4 is processed into a concavo-convex portion from above and below from the peripheral portion of the movable piece 2 by plasma etching such as PIE. The outer periphery is etched in a U shape and is separated from the movable piece 2 and one end thereof is movable. The movable electrode 4 has a supporting end portion 9 integrally connected to the piece 4.
Rotates about the support end 9.

Therefore, the movable electrode 4 moves with respect to the fixed electrodes 10 and 11 of the upper and lower fixed pieces 1 and 3 which will be described later. Further, a notch 13 is provided at a corner of the movable piece 2 so that an electric signal can be taken out from the fixed contact 12 of the lower fixed piece 3.
The movable contact 6 is formed on the insulating film 14 so that the gap between the contacts can be provided only by joining the two fixed pieces 1 and 3 above and below the movable piece 2 by the concave portion of the movable electrode 4. Has become. The movable portion is constituted by the portion where the movable contact 6 and the movable electrode 4 are provided.

The metal thin film layer 7 and the fixed contact terminal 5 are also provided.
Is also formed on the insulating film 14, and the metal thin film layer 7
Is made of a gold or gold alloy layer and is connected to a silicon single crystal wafer which is a base material of the movable piece 2. Similar to the movable piece 2, the upper and lower fixed pieces 1 and 3 are made of a silicon single crystal wafer as a base material. As shown in FIGS.
11, electrets 17, 18, fixed contacts 12, 1
9. Metal thin film layers 25 and 26 made of gold or a gold alloy layer for joining movable pieces are respectively formed, and the fixed electrodes 10 and 11 and the electrets 17 and 18 have contacts 21 and 22 directly deposited by silicon. 23 is the upper fixing piece 1
Is an electrode terminal of.

The fixed contact terminals 5 provided on the upper and lower surfaces of the movable piece 2 are fixed contacts 12 and 19 of the upper and lower fixed pieces 1 and 3, respectively.
Is a fixed contact terminal connected to. Then, the metal thin film layers 7 and 25 for joining the movable piece 2 and the upper and lower fixed pieces 1 and 3 are joined together.
And 26 are brought into contact with each other and heated while applying appropriate pressure, and the metal thin film layers for bonding 7, 25, 26 are joined.
Are eutecticized together with the base material silicon, and are mechanically and electrically connected as shown in FIG.

Here, the fixed electrodes 10 and 11 of the fixed pieces 1 and 3 facing each other from the support end 9 of the movable electrode 4 to the substantially central portion.
The fixed electrode 10 facing the movable electrode 4 is smaller than the fixed electrode 10, 11 facing the free end from the substantially central portion of the movable electrode 4 so as to have a smaller gap with the movable electrode 4. Concavo-convex portions 27 and 28 are formed on the surfaces of the fixed electrodes 10 and 11, respectively, so that the surface of the portion 11 engages with the concavities and convexities on the movable electrode 4 side through a gap.

Thus, in this embodiment, the surface of the electret 17 of the upper fixed piece 1 facing the movable electrode 4 is positive,
The surface of the electret 18 of the lower fixed piece 3 facing the movable electrode 4 is permanently polarized so as to be negative.
FIG. 6 shows the relationship between the inter-electrode distance, the electrostatic force (torque applied to the movable electrode 4), and the spring load when the absolute values of the electric charges of both electrets 17 and 18 are the same. However, although the electrostatic force and the torque due to the spring load act in opposite directions, they are shown in the same direction in FIG. In FIG. 6, a is a spring load force, b is an electrostatic force when the applied voltage is 0 V, c is an electrostatic force when a positive voltage is applied to the movable electrode 4, and d is a negative voltage to the movable electrode 4. The electrostatic force when applied is shown.

In the electrostatic drive type relay of the present embodiment, when the fixed electrodes 10 and 11 and the movable electrode 4 have the same electric potential, the fixed electrode 10 and 11 and the movable electrode 4 are 2 in the neutral position in parallel. The electrostatic forces generated by the two electrets 17 and 18 have the same magnitude, and the torque acting on the movable electrode 4 is zero. When the movable electrode 4 tilts toward the upper electret 18, the electrostatic force generated by the upper electret 17 is large, so that a torque that tends to tilt toward the upper electret 17 is generated at the movable electrode 4. On the contrary, when the movable electrode 4 tilts toward the lower electret 18, the electrostatic force generated by the lower electret 18 is large, so that the movable electrode 4 generates a torque that tends to tilt toward the lower electret 18.

When a positive voltage is applied to the movable electrode 4 using the electrode terminals 8 and 23, an absorbing force is generated in the lower electret 18 and the movable electrode 4, so that the movable electrode 4 leans toward the lower electret 18 side. Therefore, a very large contact pressure can be obtained. On the contrary, when a negative voltage is applied to the movable electrode 4, an absorbing force is generated in the upper electret 17 and the movable electrode 4, so that torque is generated in the movable electrode 4 so as to incline toward the upper electret 17.

Further, the spring force of the movable electrode 4 is 0 at the neutral position, and when the movable electrode 4 is tilted to either of the electrets 11 or 18, a torque for returning to the neutral position acts. That is, the electrostatic force and the spring force are applied in opposite directions. In FIG. 6, when a voltage is not applied to the movable electrode 4 and the movable electrode 4 is inclined to either of the electrets 11 or 18, the electrostatic force is set to be larger than the spring force. 4 retains its position and does not return to the neutral position. That is, it has two stable states.

For example, when a positive voltage is applied to the movable electrode 4 from the state of being inclined to the upper electret 17 side at first, the attraction force to the upper electret 17 becomes weak and the lower electret 18 is rotated and held. . Even if the voltage applied to the movable electrode 4 is set to 0 in this state, the state is maintained. Conversely, when a negative voltage is applied to the movable electrode 4, the reverse operation is performed. That is, the latching operation becomes possible.

FIG. 7 shows the operation when the absolute values of the charge amounts of the two electrets 17 and 18 are different. In this illustrated example, the electrification amount of the electret 11 is set to be larger. In the state where no voltage is applied to the movable electrode 4, the attraction force from the upper portion is larger, so that the movable electrode 4 is stable when it is inclined to the upper portion. Then, when a positive voltage is applied to the movable electrode 4, the attractive force from the lower portion becomes strong, and a torque that tends to incline to the lower portion acts on the movable electrode 4 and stabilizes with the contact portion closed. Then, when the applied voltage is removed, the restoring force of the spring is superior, so the spring returns to the neutral position and returns to the original position by the suction force of the upper part. In FIG. 7, a is a spring load force, b is an electrostatic force when the applied voltage is 0, and c is an electrostatic force when a positive voltage is applied to the movable electrode 4. In the case of the present embodiment, the electrostatic force at the center of the stroke can be improved, and matching with the spring load becomes easy.

Due to the above, the two electrets 17 and 1
Both the latching operation and the single operation are possible by changing the balance of the charge amount of 8. In addition, the gap between the fixed electrodes 10 and 11 facing each other from the support end 9 of the movable electrode 4 to the substantially central portion is larger than the gap between the free end side of the movable electrode 4 and the fixed electrodes 10 and 11. A large electrostatic force is obtained by using a force that is smaller due to the steps 27 and 28 and that is a combination of the electrostatic force exerted on the movable electrode 4 by the electric elements 17 and 18 and the electrostatic force caused by the externally applied voltage. It can be taken big.

Since this embodiment is constructed as described above, it becomes possible to bond three silicon wafers each having a large number of fixed pieces 1 and 3 and movable piece 2 formed thereon and then cut them out. , The production efficiency is improved. Furthermore, on the fixed pieces 1 and 3,
A fixed electrode 10 made of a highly-doped layer in the wafer,
11 may be formed, or an electrostatic drive circuit IC composed of a transistor, a diode, a resistance element, a capacitor and the like may be formed. When the drive circuit is integrally formed, it is not necessary to provide the drive circuit outside.

When operating the electrostatic relay, the applied voltage needs to be several tens of volts, but if a booster circuit is formed on the fixed pieces 1 and 3, the input operates at several volts. The movable piece 2 is shown in FIG.
It is formed by the process shown in. That is, as shown in FIG. 8A, a concave portion 32a is formed by foreign etching as shown in FIG. 8B on the upper surface of the silicon wafer 31 on which the insulating film 14 made of SiO ₂ is formed. As shown in c), the insulating film 14 is formed, and the movable electrode 4, the movable contact 6, the metal thin film piece 7 for connecting the fixed piece, and the fixed contact terminal 5 are connected to A.
It is formed by u. After that, the movable electrode 4, the movable contact 6, the fixed piece connecting metal thin film piece 7, and the fixed contact terminal 5 are covered with a protective film 33, and the concave surface 3 is anisotropically etched on the lower surface.
2b is formed ((d) in the figure). After that, the movable electrode 4, the movable contact 6, the fixed piece connecting metal thin film piece 7, and the fixed contact terminal 5 are formed of Au on the lower surface side as described above, and then the protective film 3 is formed.
Also cover the lower surface side with 3 ((e) in the figure). After that, the periphery of the movable electrode 4 is cut into a U-shape by plasma etching such as RIE. At this time, by making the mask pattern of the both-sides root portions 30 into the R shape, the both-sides root portions 30 of the movable portion can be formed into the R-shape so as to spread outward. 11A and 11B are an enlarged perspective view and a top view of the root portion 30.

By removing the protective film 33 after the separation, the movable piece 2 having the movable electrodes 4 and the like can be obtained ((f) in the same figure). The upper fixed piece 1 is formed in the process shown in FIG. That is, as shown in FIG.
Silicon wafer 31 on which the insulating film 15 made of O ₂ is formed
An uneven portion 27 is formed by anisotropic etching on the lower surface of the same (FIG. 2B), after which the insulating film at the tip of the convex portion is removed, and further the insulating film 15 on the lower surface is formed as shown in FIG. And the fixed contact 12 and the metal thin film layer 25 are formed on the same structure (d).
And the fixed electrode 10 is covered with the insulating film 15 to obtain the upper fixed piece 1 as shown in FIG.

The lower fixing piece 3 is formed in the process shown in FIG. That is, as shown in FIG. 10A, SiO ₂ is formed on the surface.
An uneven portion 28 is formed by anisotropic etching on the upper surface of the silicon wafer 31 on which the insulating film 16 made of is formed (FIG. 6B), and then the insulating film at the tip of the protruding portion is removed.
Further, an insulating film 16 is formed on the upper surface as shown in FIG. 7C, a fixed contact 12 and a metal thin film layer 25 are further formed as shown in FIG. The lower fixing piece 3 is obtained by covering it as shown in FIG. Isotropic etching may be adopted instead of anisotropic etching used in the above process.

By the way, the convex of the movable piece 2 and the fixed piece 1,
Dimensional relationships of the third uneven part 27 and 28 in the central portion of the movable piece 2 as shown in FIG. 12 (a), with respect to the bottom width W ₁₁ of the concave portion of the fixing piece 1,3 side of the concave-convex portions 27 and 28 The width W ₁₂ of the convex tip of the meshing movable piece 2 is reduced, and the height h ₂ of the convex is reduced with respect to the depth h ₁ of the facing concave, and the convex tip surface A and the fixed piece 1, The heights of the surface B of 3 are matched. Then, as shown in FIG.
The width W ₂₁ of the tip of the convex portion of Nos. 7 and ₂₈ is smaller than the bottom width W _{22 of the} valley portion adjacent to the convex of the movable piece 2. Further, by making the width W ₂₂ smaller than the width W ₁₂ of the convex tip, the weight of the movable piece 2 is reduced.

(Embodiment 2) This embodiment is the same as Embodiment 1 in that the root portion 30 of the movable piece 2 has an R shape. In the above embodiment, the movable piece 2 is improved to improve electrostatic force. Although the unevenness is formed on the surface of No. 2 and the uneven portions 27 and 28 are formed on the surfaces of the fixing pieces 1 and 3 facing the unevenness, in this embodiment, as shown in FIG.
3 to 17, the surface of the movable piece 2 is flat, and steps 27 'and 28' are formed on the fixed pieces 1 and 3 facing the movable piece 2.
Is formed.

The movable piece 2 of this embodiment is formed by the process shown in FIG. That is, as shown in FIG. 18A, a concave portion 32a is formed by anisotropic etching on the upper surface of a silicon wafer 31 having an insulating film 14 made of SiO ₂ formed on the surface as shown in FIG. The insulating film 14 is formed as shown in FIG.
The metal thin film piece 7 for connecting the fixed piece and the fixed contact terminal 5 are formed of Au. Thereafter, the movable electrode 4, the movable contact 6, the fixed-piece connecting metal thin film piece 7, and the fixed contact terminal 5 are attached to the protective film 33.
Then, the recess 32b is formed on the lower surface by anisotropic etching (FIG. 3D). Thereafter, similarly to the above, on the lower surface side, the movable electrode 4, the movable contact 6, the fixed piece connecting metal thin film piece 7,
After the fixed contact terminal 5 is formed of Au, the lower surface side is also covered with the protective film 33 ((e) in the figure). After that, the periphery of the movable electrode 4 is cut into a U-shape by plasma etching such as PIE. At this time, if the mask pattern of the root portion is R-shaped, the root portion 30 of the movable piece 2 can be R-shaped as in the first embodiment. If the protective film 33 is removed after this separation, the movable piece 2 having the movable electrode 4 and the like formed thereon can be obtained ((f) in the figure).

The upper fixed piece 1 is formed in the process shown in FIG. That is, as shown in FIG.
Silicon wafer 31 on which the insulating film 15 made of O ₂ is formed
A step 27 is formed by anisotropic etching on the lower surface of the (FIG. 2 (b)), and then the contact 21 is formed.
Further, the fixed electrode 10 is formed on the lower surface of the insulating film 15 by Au.
The fixed contact 12 and the metal thin film layer 25 are formed as shown in FIG. 2C, the electret 17 is further formed as shown in FIG. 3D, and the fixed electrode 10 is covered with the insulating film 15 to form the fixed electrode 10. The upper fixed piece 1 is obtained as in e).

The lower fixing piece 3 is formed in the process shown in FIG. That SiO ₂ on the surface, as shown in FIG. 20 (a)
A step 28 is formed by anisotropic etching on the upper surface of the silicon wafer 31 on which the insulating film 16 made of (i) is formed (the same figure (b)), and then the contact 22 is formed, and further on the upper surface of the insulating film 16 by Au. The fixed electrode 11, the fixed contact 19, and the metal thin film layer 26 are formed as shown in FIG. 7C, the electret 18 is further formed as shown in FIG. 3D, and the fixed electrode 11 is covered with the insulating film 16. Fig. (E)
As described above, the lower fixing piece 3 is obtained.

In the second embodiment, the movable piece 2 is formed by grooving.
After manufacturing the desired movable piece 2 with the root portion 30 of R-shaped, it is joined to the lower fixed piece 3 and the upper fixed piece 1, but before carrying out the groove processing of the movable piece 2 as shown in FIG. Alternatively, the movable piece 2 may be joined to the lower fixed piece 3 and then the movable piece 2 may be grooved by plasma etching such as RIE, and the root portion 30 may have an R shape.

[0031]

According to the first aspect of the present invention, the roots on both sides of the other end of the movable portion are spread outward by the R processing, so that stress concentration is prevented on both sides of the root of the other end of the movable portion. Since it does not occur, there is an effect that it is not damaged even if there is an impact from the outside. According to the configuration of the invention of claim 2, the convex portion is formed on one of the facing surfaces of the movable portion and the fixed piece, and the concave portion is formed on the other surface so that the convex portion meshes with a gap. The gap between the tip of the part and the inner wall of the recess facing it is very small, so that the electrostatic force acting on the movable electrode can be increased, and as a result, the contact pressure can be made large and the contact of the contact Improved reliability, less likely to malfunction due to external vibrations and shocks, and low applied voltage to the electrodes, especially wide gap between the movable electrode contact and the fixed electrode contact. Since it is also possible to increase the breakdown voltage between contacts, it is possible to lower the voltage of the drive circuit, and further, there is an effect that the electrostatic force at the center of the stroke is improved and spring load matching is facilitated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a first embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is a top view of the above movable piece.

FIG. 4 is a bottom view of the upper fixing piece of the above.

FIG. 5 is a top view of the lower fixing piece of the above.

FIG. 6 is a relationship characteristic diagram between the contact distance, the electrostatic force, and the spring load for explaining the above-described operation, and is an operation characteristic diagram.

FIG. 7 is a relational diagram between the contact distance, the electrostatic force, and the spring load, which is another operation explanatory diagram, and is an operation characteristic diagram.

FIG. 8 is an explanatory diagram of a process of forming the movable piece of the above.

FIG. 9 is an explanatory diagram of a forming process of the upper fixing piece of the above.

FIG. 10 is an explanatory diagram of a forming process of the lower fixing piece of the above.

FIG. 11A is an enlarged perspective view in which a part of a root portion of the above movable piece can be omitted. (B) is a top view which can abbreviate a part of root part of a movable piece same as the above.

FIG. 12 is an explanatory view of the dimensional relationship between the protrusion of the movable piece and the uneven portion of each fixed piece in the above.

FIG. 13 is a sectional view of a second embodiment of the present invention.

FIG. 14 is an exploded perspective view of the above.

FIG. 15 is a top view of the movable piece of the above.

FIG. 16 is a bottom view of the upper fixing piece of the above.

FIG. 17 is a top view of the lower fixing piece of the above.

FIG. 18 is an explanatory diagram of a process of forming the movable piece of the above.

FIG. 19 is an explanatory diagram of a forming process of the upper fixing piece of the above.

FIG. 20 is an explanatory diagram of the formation process of the lower fixing piece of the above.

FIG. 21 is a diagram illustrating another forming process of the movable piece according to the second embodiment of the present invention.

FIG. 22 is a configuration diagram of a conventional example.

[Explanation of symbols]

 1 Upper Fixed Piece 2 Movable Piece 3 Lower Fixed Piece 4 Movable Electrode 6 Moving Contact 9 Support End 10 Fixed Electrode 11 Fixed Electrode 12 Fixed Contact 17 Electret 18 Electret 19 Fixed Contact 27 Uneven Part 28 Uneven Part 30 Root

Claims (2)

[Claims] 1. A fixed electrode which has a fixed piece for forming a fixed electrode, and a movable electrode which faces the fixed electrode with a gap therebetween. The fixed electrode is generated by an electrostatic force generated by an external voltage applied between the fixed electrode and the movable electrode. A movable piece having a movable part whose other end is supported and fixed so that one end moves to the side, and a contact point that comes in contact with and separates from each other by the movement of the movable part corresponds to the one end of the movable part and this one end. In the electrostatic drive type relay which is provided at the end of the fixed piece and connects these contacts to an external electric circuit, both roots of the other end of the movable part are spread outward by R processing. Electrostatic drive type relay. 2. A convex portion is formed on either one of the facing surfaces of the movable portion and the fixed piece in the gap portion between the movable portion and the fixed piece facing the movable portion, and the convex portion is formed on the other side through the gap. The electrostatically actuated relay according to claim 1, wherein a concave portion that engages with each other is formed.