JP2008261636A - Acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a sensor capable of improving a characteristic by reducing a capacitance generated in a signal wire. <P>SOLUTION: This sensor equipped with a detection element 1 having an acceleration detection part is constituted as follows: the detection element 1 has a fixed part 4 connecting weight parts 2 through a flexible part, a counter substrate 6 facing to the weight parts 2, first to fourth counter electrodes 14, 16, 18, 20 arranged on each facing surface of the weight parts 2 and the counter substrate 6, and signal wires 21 extracted from the electrodes; the acceleration detection part detects each capacitance change of the first to fourth counter electrodes 14, 16, 18, 20 arranged on each facing surface of the weight parts 2 and the counter substrate 6, to thereby detect the acceleration; and each end of all the signal wires 21 is arranged on either side of the upper face side or the lower face side of the detection element 1, to be thereby connected electrically to a mounting substrate at each end of the signal wires 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acceleration sensor used in various electronic devices such as attitude control and navigation of a moving body such as an aircraft, an automobile, a robot, a ship, and a vehicle.

  Hereinafter, a conventional acceleration sensor will be described.

  As shown in FIG. 9, the conventional acceleration sensor includes a detection element 50 that detects acceleration, a processing circuit that calculates the acceleration by processing a detection signal detected by the detection element 50, and the processing circuit. A mounting substrate 52 on which the detection element 50 is mounted is provided. The detection element 50 includes a base substrate 53, a diaphragm 54 disposed so as to face the base substrate 53, and a weight portion 55 connected to the lower side of the diaphragm 54. A counter electrode 56 is disposed on the opposing surfaces of the base substrate 53 and the diaphragm 54 facing each other. Further, an adhesive 57 is applied to a desired portion between the base substrate 53 and the diaphragm 54, and the base substrate 53 and the diaphragm 54 are bonded and fixed by the adhesive 57. Or you may fix by another joining method.

  Next, detection of acceleration will be described.

  When acceleration occurs, the weight portion 55 tends to move in the axial direction in which the acceleration occurs, so that the diaphragm 54 on which the weight portion 55 is disposed bends. Then, since the gap between the base substrate 53 and the diaphragm 54 changes, the acceleration is detected based on the change in capacitance between the counter electrodes 56 due to the change in the gap.

  Such an acceleration sensor is used in a posture control device, a navigation device, or the like of a moving body such as a vehicle corresponding to a detection axis to be detected.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 11-344506

  In the above configuration, acceleration is detected based on the change in capacitance between the counter electrodes 56, but a signal line 59 is drawn from the counter electrode 56 disposed on the base substrate 53 and the counter electrode 56 disposed on the diaphragm 54. Yes. The end portions of these signal lines 59 are connected to electrode pads 60 and 61, and are electrically connected to the wiring pattern 62 disposed on the mounting substrate 52 by wire bonding 63 via the electrode pads 60 and 61. The

  At this time, in the above configuration, the electrode pad 60 connected to the signal line 59 drawn from the counter electrode 55 arranged on the base substrate 53 and the signal line 59 drawn from the counter electrode 56 arranged on the diaphragm 52 are provided. The connected electrode pads 61 are opposed to each other, and are electrically connected to the wiring pattern 62 of the mounting substrate 52 by wire bonding 63 in the opposed state.

  In the above configuration, since the electrode pad 60 electrically connected to the wiring pattern 62 arranged on the mounting substrate 52 is in the lower surface direction, and the electrode pad 61 is in the upper surface direction, it is difficult to electrically connect by the wire bonding 63. It had the problem that.

  An object of the present invention is to solve the above-mentioned problems and to provide an acceleration sensor that facilitates electrical connection between a wiring pattern arranged on a mounting substrate and a counter electrode.

  In order to solve the above-described problems, the present invention particularly relates to a detection element comprising: a fixed portion in which a weight portion is connected via a flexible portion; a counter substrate facing the weight portion; and the weight portion facing the counter portion. A counter electrode disposed on each counter surface of the substrate; and a signal line drawn from the counter electrode. In the acceleration detection unit, between the counter electrode disposed on each counter surface of the weight portion and the counter substrate The acceleration is detected by detecting the electrostatic capacitance of the signal line, and the end portions of all the signal lines are arranged on either the upper surface side or the lower surface side of the detection element, and at the end portions of the signal lines, The configuration is electrically connected to the mounting board.

  With the above configuration, the end portion of the signal line led out from the counter electrode disposed on the facing surface of each of the weight portion and the counter substrate is disposed on either the upper surface side or the lower surface side of the detection element. Since the end portion is electrically connected to the mounting substrate, the connection surface is unified to either the upper surface side or the lower surface side of the detection element, so that connection is facilitated. Therefore, the occurrence of poor connection and the like can be reduced, and the reliability can be improved.

  1 is an exploded perspective view of a detection element of a composite sensor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 before arrangement of the counter substrate, and FIG. 4 is a cross-sectional view taken along the line BB in FIG. 1, and FIG. 5 is a cross-sectional view taken along the line CC in FIG.

  In FIG. 1, a composite sensor according to an embodiment of the present invention includes a detection element 1 having an acceleration detection unit and an angular velocity detection unit, and the detection element 1 is fixed by connecting a weight part 2 via a flexible part. Part 4, counter substrate 6 opposed to weight part 2, first electrode disposed on each of the opposing surfaces of weight part 2 and counter substrate 6, and second electrode disposed on the flexible part.

  Specifically, the detection element 1 includes two orthogonal arms formed by connecting the first arm 8 to the second arm 10 in a substantially orthogonal direction, and a support portion 12 that supports one end of the two first arms 8. And a frame-shaped fixing portion 4 in which the other ends of the two first arms 8 are connected. The thickness of the first arm 8 is much thinner than the thickness of the second arm 10, and the second arm 10 is bent until it faces the second arm 10 itself, and the tip of the bent second arm 10 is bent. The weight part 2 is connected to the part. The first arm 8 and the support portion 12 are arranged on substantially the same straight line, and the first arm 8 and the second arm 10 are arranged symmetrically with respect to the center of the detection element 1. Here, the flexible portion refers to a portion connecting the fixed portion 4 and the weight portion 2, and the first arm 8 and the second arm 10 correspond to at least the flexible portion.

  A counter substrate 6 is disposed so as to face the weight portion 2. The counter substrate 6 is opposed to the weight portion 2 by a protrusion 13 through a certain gap. At this time, if the adhesive is applied to a desired position, the fixing portion 4 and the counter substrate 6 can be easily fixed.

  First counter electrode to fourth counter electrode 14, 16, 18, 20 are arranged as first electrodes on the opposing surfaces of the weight portion 2 and the counter substrate 6, and one of the two second arms 10 facing each other. Includes a drive electrode 22 and a detection electrode 24 that drive and vibrate the weight portion 2, and the other two second arms 10 that face each other have a first sensing that senses distortion of the second arm 10 as a second electrode. An electrode 26 and a second sensing electrode 28 are disposed. Further, the signal line 21 extended from the first counter electrode to the fourth counter electrode 14, 16, 18, 20 arranged on the weight part 2 is connected to the fixing part 4 via the second arm 10 and the first arm 8. The electrode pads 23 are provided up to.

  The first to fourth counter electrodes 14, 16, 18, 20, the drive electrode 22, the detection electrode 24, the first detection electrode 26, and the second detection electrode 28 arranged in the weight portion 2 are shown in FIGS. 3 includes an upper electrode 32 and a lower electrode 34 with a piezoelectric layer 30 interposed therebetween, and the signal line 21 has the same configuration.

  Further, the end portions of all the signal lines 21 are arranged as electrode pads 23 on the upper surface side of the fixing portion 4 of the detection element 1, and wire bonding or the like is performed at the electrode pads 23 that are the end portions of the signal lines 21. Is electrically connected to the wiring pattern of the mounting board. At this time, the signal lines 21 drawn from the first to fourth counter electrodes 14, 16, 18, and 20 arranged on the counter substrate 6 are drawn to the fixing portion 4 through the conductive paste 15.

  The counter substrate 6 is made of high resistance silicon or an insulating substrate. The fixed portion 4, the first arm 8, the second arm 10, and the weight portion 2 are made of a semiconductor substrate or an insulating substrate made of silicon or the like having a higher resistance than the lower electrode 34, and the fixed portion 4, the first arm 8, The two arms 10 and the weight portion 2 are integrally formed.

  Next, the angular velocity detection unit and the acceleration detection unit will be described.

  First, the angular velocity detection unit will be described.

  As shown in FIG. 6, when the first arm 8 of the detection element 1 is arranged in the X-axis direction and the second arm 10 is arranged in the Y-axis direction on the X axis, Y axis, and Z axis orthogonal to each other, When an AC voltage having a resonance frequency is applied to the drive electrode 22, the second arm 10 is driven to vibrate starting from the second arm 10 on which the drive electrode 22 is disposed, and accordingly, the weight portion 2 is also opposed to the second arm 10. Drive vibration occurs in the drive vibration direction indicated by the solid arrow and the dotted arrow. In addition, all of the four second arms 10 and the four weight portions 2 are synchronously driven and vibrated in the opposite direction of the second arm 10. The driving vibration direction in the detection element 1 is the X-axis direction.

  At this time, for example, when an angular velocity is generated around the left of the Z-axis, in synchronization with the drive vibration of the weight portion 2, a direction perpendicular to the drive vibration direction with respect to the weight portion 2 (solid arrow and dotted arrow) Since the Coriolis force is generated in the Coriolis direction (Y-axis direction) described above, distortion caused by the angular velocity around the left of the Z-axis can be generated in the second arm 10. That is, a voltage is output from the first and second sensing electrodes 28 due to a change in the state of the second arm 10 that is bent due to the Coriolis force (strain generated in the second arm 10), and the angular velocity is based on the output voltage. Is detected.

  Next, the acceleration detection unit will be described.

  As shown in FIG. 7, when the counter substrate 6 is arranged on the XY plane in the X axis, the Y axis, and the Z axis orthogonal to each other, if no acceleration is generated, the surface of the counter substrate 6 facing the weight portion 2 is not affected. The gap (H1) of the first counter electrode 14 is equal to the gap (H2) of the second counter electrode 16 on the facing surface of the counter substrate 6 and the weight portion 2. Although not shown, the facing distance of the third counter electrode 18 and the gap of the fourth counter electrode 20 are also equal.

  At this time, for example, when acceleration occurs in the X-axis direction, the weight portion 2 tends to rotate around the Y-axis around the support portion 12 as shown in FIG. As a result, the gap (H1) between the counter substrate 6 and the first counter electrode 14 on the counter surface of the weight part 2 is reduced, and the gap (H2) between the counter electrode 6 and the counter electrode 6 on the counter surface of the weight part 2 is reduced. Becomes larger. The same applies to the facing distance of the third counter electrode 18 and the gap between the fourth counter electrode 20.

  On the other hand, when acceleration occurs in the Y-axis direction, the weight portion 2 tries to rotate around the X-axis around the support portion 12. For example, the gap between the third and fourth counter electrodes 18 and 20 is, for example, Increases, and the gap between the first and second counter electrodes 14, 16 decreases. That is, since the capacitance between the electrodes changes, acceleration in the X-axis direction or Y-axis direction is detected based on the change in capacitance.

  With the above configuration, the acceleration detection unit detects the capacitances of the first to fourth counter electrodes 14, 16, 18, and 20 disposed on the opposing surfaces of the weight unit 2 and the counter substrate 6, and thereby accelerates the acceleration. The change in the state of the flexible part that is bent due to the Coriolis force can be detected by the first sensing electrode 26 and the second sensing electrode 28, and the acceleration and angular velocity can be detected by the single detection element 1. Therefore, the mounting area can be reduced and the size can be reduced.

  In addition, an electrode pad 23 that is an end portion of the signal line 21 led out from the first counter electrode to the fourth counter electrodes 14, 16, 18, 20 disposed on the opposing surfaces of the weight portion 2 and the counter substrate 6, Since it is arranged on the upper surface side of the detection element 1 and is electrically connected to the wiring pattern arranged on the mounting substrate by wire bonding or the like at this electrode pad 23, the connection surface of the electrode pad 23 is the detection element 1. Since it is unified on the upper surface side, it can be easily connected to the mounting board. Therefore, the occurrence of poor connection and the like can be reduced, and the reliability can be improved. The ends of all the signal lines 21 are arranged on either the fixed part 4 or the counter substrate 6, and the ends of all the signal lines 21 are arranged on either the upper surface side or the lower surface side of the detection element 1. What is necessary is just to electrically connect with the mounting substrate at the end of the signal line 21.

  Further, since the signal line 21 drawn from the first to fourth counter electrodes 14, 16, 18, 20 arranged on the counter substrate 6 is drawn to the fixing portion 4 via the conductive paste 15, the electrode pad 23 can be easily arranged on the upper surface side of the detection element 1.

  In the embodiment of the present invention, the signal line 21 led out from the first counter electrode to the fourth counter electrode 14, 16, 18, 20 arranged on the counter substrate 6 is connected to the fixing portion 4 via the conductive paste 15. The signal line 21 drawn out from the first counter electrode to the fourth counter electrode 14, 16, 18, 20 is drawn out to the fixing part 4 through the conductive paste 15, but the first counter electrode arranged in the weight part 2. The signal lines 21 drawn from the fourth counter electrodes 14, 16, 18, and 20 may be drawn to the counter substrate 6 through the conductive paste 15. Thus, by pulling out the signal line 21 to the counter substrate 6 side, the degree of freedom in routing the signal line is improved. Further, since the insulating substrate can be used for the counter substrate 6, there is an advantage that no capacitance is generated between the signal lines and between the other wirings.

  The signal lines 21 drawn from the first counter electrode to the fourth counter electrodes 14, 16, 18, and 20 arranged on the weight portion 2 are drawn to the flexible substrate, and the first to fourth electrodes arranged on the counter substrate 6 to the fourth counter electrode 6. You may arrange | position on the same surface side as the signal wire | line 21 pulled out from the counter electrodes 14, 16, 18, and 20. Conversely, the signal line 21 drawn from the first to fourth counter electrodes 14, 16, 18, and 20 disposed on the counter substrate 6 is drawn out to a flexible flexible substrate such as plastic, and a weight portion 2 may be arranged on the same side as the signal line 21 drawn from the first counter electrode to the fourth counter electrode 14, 16, 18, 20. The flexible substrate can be bent or deformed according to the arrangement state, and the design of the routing of the signal line 21 becomes easy. In this detection element 1, a flexible substrate is electrically connected in advance to the signal line 21 arranged on the counter substrate 6, and the counter substrate 6 to which the flexible substrate is connected is placed on the protrusion 13 of the fixing unit 4. Then, it may be formed.

  The acceleration sensor according to the present invention is less susceptible to variations in capacitance change, can improve detection accuracy, and can be applied to various electronic devices.

The disassembled perspective view of the detection element of the composite sensor in one embodiment of this invention AA sectional view before arrangement of the counter substrate in FIG. BB sectional view before arrangement of the counter substrate in FIG. BB sectional view at the time of arrangement of the counter substrate in FIG. 1. CC sectional drawing at the time of opposing board | substrate arrangement | positioning in FIG. Explanatory drawing which shows the operation state of the detection element at the time of angular velocity generation Cross section of the detector Explanatory drawing which shows the operation state of the detection element at the time of acceleration generation Cross-sectional view of a conventional acceleration sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection element 2 Weight part 4 Fixed part 6 Opposite substrate 8 1st arm 10 2nd arm 12 Support part 13 Projection part 14 1st counter electrode 15 Conductive paste 16 2nd counter electrode 18 3rd counter electrode 20 4th counter electrode 21 signal line 22 drive electrode 23 electrode pad 24 sensing electrode 26 first sensing electrode 28 second sensing electrode 30 piezoelectric layer 32 upper electrode 34 lower electrode

Claims (6)

A detection element having an acceleration detection unit;
The detection element includes a fixed part that connects a weight part via a flexible part, a counter substrate that is opposed to the weight part, a counter electrode that is disposed on each of the opposing surfaces of the weight part and the counter substrate, A signal line led out from the counter electrode, and the acceleration detection unit detects an acceleration by detecting a capacitance between the counter electrode disposed on the counter surface of each of the weight part and the counter substrate. And
An acceleration sensor in which end portions of all the signal lines are arranged on either the upper surface side or the lower surface side of the detection element and are electrically connected to a mounting substrate at the end portions of the signal lines. The acceleration sensor according to claim 1, wherein end portions of all the signal lines are arranged on either the fixed portion or the counter substrate. The acceleration sensor according to claim 2, wherein a signal line drawn from a counter electrode arranged on the counter substrate is drawn to the fixing portion via a conductive paste. The acceleration sensor according to claim 2, wherein the signal line drawn from the counter electrode arranged in the weight portion is drawn to the counter substrate via a conductive paste. The acceleration sensor according to claim 1, wherein the signal line drawn from the counter electrode arranged on the weight portion is drawn out to the flexible substrate, and is arranged on the same surface side as the signal line drawn from the counter electrode arranged on the counter substrate. The acceleration sensor according to claim 1, wherein the signal line drawn from the counter electrode arranged on the counter substrate is drawn out to the flexible substrate, and is arranged on the same side as the signal line drawn from the counter electrode arranged on the weight portion.

Images