JP2002090384A - Structure of motion sensor and internal connecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode connecting structure and connecting method for a sensor vibration body inside a motion sensor, suitable for connecting the plate-shaped sensor vibration body, being rationally manufactured, reducing the cost, enhancing the durability, making the size small, preventing application of strong force to the sensor vibration body, and suitable for a vessel for SMD packaging. SOLUTION: This motion sensor contains an internal electrode accommodating for the outside of the vessel and the sensor vibration body supported inside the vessel, and each internal electrode is connected to each electrode film on the surface of the sensor vibration body with a small, block-shaped conductive chip. The internal electrode surface and the electrode film surface, on which the conductive chip is placed, are made flush with each other. The constitution of a disk-shaped acceleration sensor is presented as an example of suitable structure. Internal connection method for placing and brazing the conductive chip with a multipurpose packaging machine is presented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a motion sensor and an internal connection method. More specifically, the present invention relates to a structure and a connection method for connecting an electrode film of a sensor vibrator inside a container and an inner end of an electrode connected to an external terminal electrode of the container by using a block-shaped conductive chip inside a motion sensor. .

[0002]

2. Description of the Related Art Conventionally, an acceleration sensor (measuring a linear acceleration by detecting a deflection of a sensor body and a change in an oscillation frequency due to an inertial force acting on a load mass) and an angular velocity sensor (a Coriolis force acting on a vibrating mass) are known. Various types of mechanical vibrators have been proposed which play a role of a so-called vibrating gyroscope which detects a change in deflection of the vibrating body due to the vibration and measures a rotational angular velocity. In order to hold these relatively small vibrators in a predetermined environment, protect them from external force and the like, and stabilize their characteristics, they are usually mounted and sealed in an airtight or vacuum container. These containers are provided with a required number of external electrodes (terminals), the terminal conductors penetrate the wall of the container, and a detection or driving electrode film disposed on the surface of the sensor vibrator inside the container. Is electrically connected to

There are various conventional connection methods. Most directly, the lead wire is soldered. As an advanced method, a technique for an integrated circuit is often used. For example, as a typical example, the wire bonding technique is based on a part of the electrode film on the sensor vibrator or an electrode pad connected to the electrode film, and a terminal pin penetrating the container (each pin is insulated by a glass member or the like). Is connected by crimping both ends of a thin wire made of gold or aluminum to the end face.

[0004]

The soldering method is extremely time-consuming and inevitably increases the manufacturing cost of the motion sensor. In addition, it is difficult to control the amount of solder and the variation is large, which affects the characteristics of the sensor. There is a problem that it is easy. In addition, the wire bonding method has a problem of strength against extremely large impact due to the thin wire, and requires some space around to allow deformation of the wire,
Further, it is necessary to completely hermetically seal the container in order to protect the thin wire, and when the vibrator is fragile, a capillary that holds the wire and applies a pressing force during the connection operation may damage the vibrator. Further, a package in which terminal pins are vertically exposed to the outer surface of the container is not suitable for use in mounting a motion sensor in a container on a printed circuit board simultaneously with other chip components by SMD.

An object of the present invention is suitable for connection of a sensor vibrator in which an electrode film is arranged on a plate surface, which is reasonable in production, low in cost, has strength and durability, and may damage the sensor vibrator. It is an object of the present invention to provide an electrode connection structure and a connection method of a sensor vibrator in a motion sensor that can be configured in a small size, and that is suitable for an SMD mounting container.

[0006]

To achieve the above object, the structure of the motion sensor according to the present invention has the following features. (1) A structure of a motion sensor including a container and a sensor vibrator inside the container, wherein the container is formed in a substantially rectangular box shape having a lid member and a base made of an insulating material, and has an outer surface on the base side. Is provided with a required number of external electrodes, the plurality of external electrodes are respectively connected to the internal electrodes of the base, and the sensor vibrator has a plurality of electrode films for piezoelectrically detecting its movement. On the surface, and each of the internal electrodes and each of the electrode films are connected by a small block-shaped conductive chip.

The structure of the motion sensor of the present invention may further have at least one of the following features. (2) The upper surfaces of the plurality of electrode films are on a first plane that is a main surface of the sensor vibrator, and the upper surfaces of the plurality of internal electrodes are on a second plane inside the base. The sensor vibrator is configured such that the first plane is at the same height as the second plane, and a part of the contour of each of the electrode films and a part of the contour of the internal electrode are close to each other. The electrode film and the internal electrode are further connected to each other by the conductive chip that straddles a part of each of the contours that is close to each other.

(3) The sensor vibrator is a sensor vibrator for detecting acceleration, has a disk shape having its periphery fixed to the container, has a load mass on a central axis, and has a load mass on a top surface. Comprising at least four fan-shaped electrode films for piezoelectrically detecting the deformation of the disk, comprising at least four internal electrodes proximate to the outside of each of the fan-shaped electrode films;
The upper surface of each internal electrode and each of the fan-shaped electrode films are connected by the conductive chip.

The internal connection method of the motion sensor according to the present invention has the following features. (4) A method of electrically connecting each of the plurality of electrode films of the sensor vibrator supported inside the container and the surfaces of the plurality of internal electrodes communicating with the external electrodes of the container, wherein The upper surface of the electrode film and the upper surface of the plurality of internal electrodes are substantially on the same plane, and a part of the outline of each of the plurality of electrode films and the outline of each of the plurality of terminal conductors corresponding thereto. A first step of supporting the sensor vibrator inside the container from which the lid member has been removed so that a part thereof is close to each other, and the upper surface of the electrode film and the upper surface of the internal electrode are close to each other A second step of applying a paste containing a brazing material to a portion, and a block-shaped conductive chip placed on both ends of the portion where the paste containing the brazing material is applied by a mounting machine capable of handling chip-shaped electronic components. Place so that it touches Include a third step, a fourth step of brazing said conductive tip by melting the brazing material by heating in this order.

[0010]

FIG. 1 is an internal plan view of an acceleration sensor which is an example of a motion sensor according to an embodiment of the present invention. In order to show the internal structure, a top lid 1c is removed, and a spacer 1b is also removed. There is a cutout. FIG. 2 is a central sectional view of an example of the same embodiment. Reference numeral 1 denotes a substantially box-shaped container, which is a base 1a made of an insulating material such as plastic or ceramic, a frame-shaped spacer 1b made of an insulating material adhered on its upper surface, and a flat plate adhered on its upper surface. (Which may be a metal plate) so that a necessary degree of airtightness can be maintained by an adhesive or a resin melted during the manufacturing process. 2a is an external electrode, and there are four lead frame members made of a metal plate (A, B,
C and D), which are in close contact with the four peripheral surfaces of the base 1a of the container 1 and the peripheral portion of the bottom surface. The upper end is folded along the upper surface of the base 1a (there is a depression on the upper surface of the base 1a, which sinks the thickness), penetrates under the spacer 1b and penetrates the container 1, and the inner end has a narrow width and the internal electrode has a narrow width. 2b.

Reference numeral 3 denotes a sensor vibrator. The main body is a relatively thin disk-shaped sensor diaphragm 3a, which is made of a metal material such as an elinvar whose elastic modulus has a small temperature change. The outer periphery of the sensor diaphragm 3a is joined to a sufficiently thick cylindrical base 3e (which may be integrally formed with the sensor diaphragm 3a or a separate cylindrical member may be joined by welding or the like). Therefore, the sensor diaphragm 3a is a disk fixed to the periphery. At the center of the sensor diaphragm 3a, a cylindrical load mass 3f made of metal is fixed at a fixing portion 3g (for both press-fitting and welding).

A piezoelectric ceramic plate 3b, which is a disk made of a piezoelectric ceramic material (having a diameter slightly smaller than the outer diameter of the sensor vibrator 3), is adhered and integrated on the upper surface of the sensor diaphragm 3a. . This is polarized so that piezoelectricity appears on both sides of the plate when the plate surface expands and contracts, and the upper electrode film 3c (detection electrodes, A, B, , C, and D, which correspond to the respective external electrodes 2a having the same symbols), and a lower electrode film 3d (which serves as a reference electrode) is formed on the lower surface.
Are provided on the entire surface. For convenience of illustration, the sensor diaphragm 3a, the piezoelectric ceramic plate 3b, the upper electrode film 3c, and the lower electrode film 3
The thickness in the sectional view (d) (FIG. 2) is exaggerated (particularly, upper and lower electrode films).

Since the sensor vibrating body 3 has the above-described configuration, the sensor vibrating plate 3a and the piezoelectric ceramic plate 3b are integrally formed to form a disk-shaped vibrating body fixed at the periphery and deformable with a load mass. Then, a voltage is generated in each upper electrode film 3c with respect to the lower electrode film 3d as a reference electrode in accordance with the deformation of the disk-shaped vibrator. Note that the sensor vibrator 3 in this example does not have self-excited oscillation means and does not vibrate by itself. However, in principle, the sensor vibrator 3 has a structure capable of free damping vibration when an external force is applied.
Was named. For example, even when a strong damping means is added to a disk-shaped vibrating body (such as laminating a plate material having a large internal friction) so that the response when a shock is applied becomes non-vibrating, the essential configuration is obtained. Since the operation does not change, the name of the “vibrating body” will be applied.

The completed sensor vibrator 3 is fitted in a cylindrical recess of the base 1. This is a motion sensor manufacturing (assembly)
This is the first step. At this time, each corresponding upper electrode film 3c
And each internal electrode 2b are oriented so as to correctly face each other. At this time, the upper surface of each upper electrode film 3c and the upper surface of each internal electrode 2b (the uppermost surface of the electrode film of the sensor vibrator, which is the main surface) are at the same height position in a sectional view, that is, substantially the same. They are on a plane and their outlines (edges) in plan view
Are designed to be close to each other with a slight gap therebetween.
An external electrode E2c is provided at the center of the bottom surface of the base 1a.
It is connected to the internal electrode E2d in the cylindrical concave portion by a rod-shaped connecting electrode member 2e penetrating the bottom of the base.
This comes into contact with the metal base 3e of the sensor vibrating body 3, and eventually conducts with the lower electrode film 3d (that is, the reference electrode) of the piezoelectric ceramic plate 3b, and the external electrode E2c is the external terminal.

The internal electrode 2b and the upper electrode film 3c are connected by bridging the conductive chip 4. The conductor chip 4 is made of, for example, a copper alloy, and if necessary, is plated with good wettability on a brazing material, has a block shape, and has a size of, for example, 1 × 0.5 ×
0.35 mm, which is set to the same size as commonly used electronic components such as square chip resistors and capacitors. After the assembly of the sensor vibrator 3 is completed, the base 1 with the lid 1c not yet closed and the upper surface open is set horizontally, and first, for example, solder is placed at a predetermined position on the upper surface of the four pairs of electrodes to be bridged. A paste-like brazing material obtained by kneading fine particles and a flux or a binder is applied or supplied. This is the second step.

Next, four conductive chips 4 are mounted thereon. This is the third step. In this state, when the substrate is passed through a heating furnace, the brazing material 5 is melted, and the internal electrode 2b and the upper electrode film 3c are firmly connected by the conductive chip 4 as shown in the figure. This is the fourth step. The motion sensor in which the container 1 is completely sealed may be mounted on a printed board for use by SMD (the lower surfaces of the four external electrodes A, B, C, D2a and the external electrode E2c may be mounted on the printed board). Joined with the pattern). In many cases, a normal eutectic solder may be used as the solder material of the brazing material 5 used in this example. However, depending on the heating conditions at the time of SMD mounting, a high-temperature solder is used to protect the internal connection to a higher degree. Sometimes.

In the mounting step of the conductive chip 4, the chip-shaped electronic component is correctly mounted at a designated position on the printed circuit board. In this case, there is no need to press it just to place it, and there is almost no possibility that the sensor vibrator may be damaged by excessive pressure. It is advantageous to use a general-purpose automatic mounting machine, such as a chip mounter, developed and marketed for the purpose of making SMD mounting quick and easy. In normal component mounting, chip components are, for example, supplied in a predetermined direction on a tape with an adhesive so as to be easily gripped by a machine, and are wound around a reel and supplied, but are used in the present invention. The conductive chip 4 may be supplied in the same manner. In this way, the internal connection of the motion sensor in the container can be automatically performed with a small number of man-hours without requiring any manpower, and furthermore, a connection that is sufficiently strong and fragile and does not require a strong force at the time of joining. The structure is obtained. This embodiment also sets the motion sensor to S
As described above, it can be used as a circuit component for MD mounting.

Finally, how the motion sensor of this embodiment functions as a three-axis acceleration sensor will be described. The direction is described by the XYZ coordinate axes shown in FIGS. Now, when the entire motion sensor performs an acceleration motion in the downward direction (−Z direction), an upward (+ Z direction) inertia force acts on the additional mass 3f, and pushes up the center of the peripherally fixed sensor diaphragm 3a to be convex upward. The piezoelectric ceramic plate 3b which is deformed and laminated and bonded thereto is subjected to all radially extending strains. As a result, the upper electrode films 3cA, B,
In C and D, a voltage of the same sign and an equal amount (for example, + V) is generated with respect to the lower electrode film 3d (reference electrode).

When the motion sensor performs an acceleration motion to the left (−X direction) in the figure, the additional mass 3f is directed rightward (+ X
Direction) inertia force acts. Since the center of gravity of the additional mass 3f is eccentric below the sensor diaphragm 3a, the distortion of the piezoelectric ceramic plate 3b is reduced by the moment of inertia force, and the upper electrode film A3
In the region covered by c, the upper electrode film A3c is mainly convex downward.
For example, a voltage of -V 'is generated with respect to the lower electrode film 3d (reference electrode), and + V' is generated mainly in an area covered by the upper electrode film B3c, and becomes convex. At that time, in the region covered by the upper electrode film C or D3c, the upwardly convex deformation and the downwardly convex deformation are generated in equal amounts, respectively, so that the positive and negative charges cancel each other,
No voltage is generated from both electrodes. Further, although the conductive tip is rigid, it is arranged on the peripheral edge to which the sensor diaphragm 3a is fixed, so that it hardly hinders free deformation of the sensor diaphragm 3a and does not affect the measurement.

When the motion sensor accelerates in the -Y direction, the mechanism and symmetry are the same as those in the -X direction.
-V 'for the upper electrode film C3c and + V' for the upper electrode film D3c.
Is generated with respect to the lower electrode film 3d (reference electrode).
In any case, the generated voltage value is proportional to the magnitude of the acceleration. The acceleration components in the three axial directions are αX, αY, αZ, and each of the upper electrode films A, B, C, D3c is a lower electrode film (reference electrode) E.
The voltages generated for 3d are VA, VB, VC, VD
And the proportional constants are K1 and K2, the following three equations hold. αX = K1 (VA−VB) (1) αY = K1 (VC−VD) (2) αZ = K2 (VA + VB + VC + VD) (3) These operations are performed on the five external electrodes 2a and 2c. By using a connected detection circuit (not shown), acceleration components in three directions can be separately measured.

Although the embodiment relating to the acceleration sensor having the disk-type sensor vibrator has been described above, the scope of the present invention is not limited to the above-described embodiment. First, in this embodiment, a conductive chip which is a metal block is used. However, a chip resistance component having a nominal value of 0Ω and sold under the name of a chip jumper, for example, may be used. Since the base material of this part is ceramics,
It is considered that the conductive chip of the embodiment of the present invention using a metal material such as phosphor bronze has higher toughness and better strength.

In this embodiment, the reference electrode is drawn to the lower surface of the container. However, it can be drawn to the external electrode on the side surface of the container like the detection electrode. In the structure example, a small circular reference electrode region is provided on the upper surface of the central portion of the piezoelectric ceramic plate (this is connected to the reference electrode on the lower surface through a through hole), and reaches the peripheral portion of the piezoelectric ceramic plate from the circular region. One to four thin upper-surface lead patterns for the reference electrode are provided so as to pass through the gap (slightly widened) between the detection sector electrodes, and an external electrode is connected to an appropriate position on the side surface of the container again. An internal electrode is provided for a reference electrode, and the internal electrode and the outer end of the upper surface lead pattern are connected by a conductive chip. In this structural example, the number of external electrodes and conductive chips increases to, for example, 5 to 8 including those for detection electrodes, but the external electrode E2c only on the lower surface of the container is not required. In the SMD mounting, an external electrode with a side electrode is more preferable because the escape of excess solder is secured by the wetting of the solder.

The sensor vibrator may be of another form, for example, a vibratory gyroscope sensor vibrator such as a tuning fork for angular velocity measurement molded from a piezoelectric material such as a quartz plate. In such a case, the base of the driving (excitation) electrode film disposed on the surface of each vibrating leg of the tuning fork and the lead wire from the electrode film for detection do not vibrate (for the purpose of being supported by the connecting portion of each leg of the tuning fork). The inner electrode group may be brought close to the outside of the edge of the tuning fork base, and the electrode surfaces that are brought into close contact with each other may be connected by a block-shaped conductive chip. Further, the structure on the container side is not limited to the illustrated example. For example, the material of the container may be ceramics, and the external and internal electrodes may be conductive films or the like printed on the inner and outer surfaces of the container instead of the lead frame. In addition, various changes in the configuration may be considered as necessary.

[0024]

The motion sensor according to the present invention has a structure in which each of the internal electrodes and each of the electrode films are connected by a small block-shaped conductive chip. Suitable for connecting sensor vibrators with membranes arranged,
Reasonably manufactured, low cost, strong and durable, there is no danger of damaging the sensor vibrator by applying strong force, and the conductive chip is small and no surrounding space is required, so it can be made compact and can be used for SMD mounting containers. Also, there is an effect that a suitable motion sensor can be provided.

Further, by adding a configuration in which the respective electrode films and the upper surfaces of the respective internal electrodes are aligned on the same plane, the arrangement of the conductive chips before connection becomes extremely easy and accurate, so that the quality and the quality of the product can be improved. This has the effect of stabilizing costs better.

Further, by applying the technique of the present invention to an acceleration sensor having a disk-shaped vibrator and a fan-shaped electrode film, the deformation of the sensor vibrator can be prevented with an extremely rational and simple configuration. There is an effect of being able to provide an acceleration sensor with no fear, that is, an inexpensive and reliable operation (capable of detecting in multiple axial directions).

Further, according to the internal connection method of the present invention, in which a conductive chip is placed over an electrode film and an internal electrode by using a mounting device for chip parts and then brazed, the electrode film is arranged on a plate surface. It is advantageous in that it can provide a motion sensor that is suitable for connection of a sensor vibrator that is manufactured, is reasonable in manufacturing, has low cost, has strength and durability, can be configured in a small size, and is suitable for a container for mounting an SMD.

[Brief description of the drawings]

FIG. 1 is an internal plan view of an example of an embodiment of the present invention.

FIG. 2 is a central sectional view of an example of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 1a Base 1b Spacer 1c Lid 2a External electrode 2b Internal electrode 2c External electrode E 2d Internal electrode E 2e Connecting electrode member 3 Sensor vibrating body 3a Sensor vibrating plate 3b Piezoelectric ceramic plate 3c Upper electrode film 3d Lower electrode film 3e Base 3f Load Mass 3g Fixed part 4 Conductive chip 5 Brazing material X, Y, Z coordinate axes

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) // G01C 19/56 H01L 41/08 Z

Claims (4)

[Claims] 1. A structure of a motion sensor including a container and a sensor vibrator in the container, wherein the container is formed in a substantially rectangular parallelepiped box shape including a lid member and a base made of an insulating material. A necessary number of external electrodes are provided on the external surface, and the plurality of external electrodes are respectively connected to the internal electrodes of the base, and the sensor vibrator includes a plurality of piezoelectric elements for detecting the movement thereof in a piezoelectric manner. A motion sensor structure having an electrode film on a surface, and wherein each of the internal electrodes and each of the electrode films are connected by a small block-shaped conductive chip. 2. An upper surface of the plurality of electrode films is on a first plane which is a main surface of the sensor vibrator, and an upper surface of the plurality of internal electrodes is on a second plane inside the base. ,
The sensor vibrator is configured such that the first plane is at the same height as the second plane, and a part of a contour of each of the electrode films and a part of a contour of the internal electrode are close to each other. 2. The method according to claim 1, wherein the electrode film and the internal electrode are supported by the base, and the electrode film and the internal electrode are connected by the conductive chip which straddles a part of each of the contours which is close to each other. Of motion sensor. 3. The sensor vibrator is a sensor vibrator that detects acceleration, has a disk shape with its periphery fixed to the container, has a load mass on a central axis, and has a load mass on an upper surface. The apparatus further comprises: at least four sector-shaped electrode films for piezoelectrically detecting deformation of a disk; and at least four internal electrodes proximate to the outside of each of the sector-shaped electrode films; 3. The structure of the motion sensor according to claim 2, wherein an upper surface and each of said fan-shaped electrode films are connected by said conductive chip. 4. A method of electrically connecting each of a plurality of electrode films of a sensor vibrator supported inside a container and surfaces of a plurality of internal electrodes communicating with external electrodes of the container, wherein The upper surfaces of the plurality of electrode films and the upper surfaces of the plurality of internal electrodes are substantially on the same plane, and a part of the contour of each of the plurality of electrode films and each of the plurality of terminal conductors corresponding thereto. A first step of supporting the sensor vibrating body inside the container from which the lid member has been removed so that a part of the contour is close to each other, and a step in which the upper surface of the electrode film and the upper surface of the internal electrode are close to each other. A second step of applying a paste containing a brazing material to a portion where the solder paste is applied, and a block-shaped conductive chip applied to both ends of the paste containing the brazing material by a mounting machine capable of handling chip-shaped electronic components. Placed in contact with the part And a fourth step of melting the brazing material by heating and brazing the conductive chip in this order.