JPS6056314B2 - Pressure/vibration-electrical conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure/vibration-to-electrical conversion device, and is a device that can detect pressure, vibration, acceleration, etc. simultaneously or individually.

Conventionally, the structures commonly used to detect vibrations, acceleration, etc. are a cantilever with a sensitive mass at the tip or a double-sided fixed pole with a sensitive mass in the center, etc. There are gauges, but the structure and electrode removal are troublesome and costly, and detectors installed in cars etc. need to detect temperature, pressure, position, etc., so they are placed in small confined spaces. However, there were problems in terms of size and cost.

The present invention is intended to solve the above problems,
It is an object of the present invention to provide a pressure/vibration-to-electrical conversion device that allows the device to be made smaller and lower in cost, and in which a sensitive mass element can be easily and freely set on a diaphragm.

Therefore, in the present invention, a silicon substrate in which a thin-walled diaphragm portion that responds to the pressure to be measured and a thick-walled support body are integrally formed, and a strain-sensitive element formed on one principal surface of the diaphragm portion; , a first metal film having a predetermined pattern formed substantially in the center of one main surface of the diaphragm part, and a first metal film formed on the support body on the same main surface side as the one main surface of the diaphragm part, a second metal film serving as an external extraction electrode for extracting a signal from the strain-sensitive element to the outside; and a solder layer formed on the first and second metal films; The membrane and the solder layer formed on the first metal membrane constitute a receiving mass element that responds to the vibrations of the diaphragm itself, and the pressure to be measured and the vibrations of the diaphragm itself are combined with the same electromagnetic distortion. It is characterized by having a configuration in which detection is performed using an element. Next, in order to better understand the present invention, a concrete explanation will be given using an example in which the diaphragm is made of single crystal silicon as shown in the drawings.

Figures 1 and 2 are a plan view and a side sectional view,
Reference numeral 1 denotes an insulator base made of, for example, crystallized glass having a coefficient of thermal expansion substantially equal to that of single crystal silicon, and a through hole 2 of a predetermined size is formed in the insulator base 1. 3 is a conductor layer, 4 is a first adhesive part, these are formed using a conductor paste such as silver-platinum or silver-palladium by a method such as screen printing, and 5 is an insulator part, which is formed by a method such as screen printing, etc. It is made of an insulating material such as glass in areas other than the parts and the part where the solder layer 6 is formed.

Further, the solder layer 6 is formed only on the conductor layer 3 and the first bonding section 4 that are not covered with the insulator section 5. Next, FIGS. 3 and 4 show a diaphragm chip that is attached to the insulator base 1, and this diaphragm chip has an N-type (100) single crystal silicon substrate of 0.6 to 1.5 Ωα, for example. Diffusion of P-type boron into strain gauge 8
are formed, and each strain gauge 8 is arranged symmetrically in the same crystal axis direction.

Further, 9 is an insulating layer, and 10 is a thin-walled diaphragm, which is shaped like a thin diaphragm in order to apply stress strain to each strain gauge 8 according to the pressure to be measured. It is formed by etching. and 1
0a constitutes a support body of the diaphragm 10. Further, on the insulator layer 9, there are a second adhesive part 11 having a diameter larger than the diameter of the diaphragm part 10, an extraction electrode 12 for extracting the signal of the strain cage 8 to the outside, and a second adhesive part 12 for detecting and amplifying applied vibrations. Sensitive mass part 13 is A1-Cr-Cu, Cr-
It is formed by vapor deposition and plating of various metals such as Cu,
A solder layer 14 is formed on the second bonding part 11, the external electrode 12, and the sensitive mass part 13. Further, in this embodiment, the wiring from the strain gauge 8 to the external electrode 12 was formed using a high concentration diffusion layer 15 of boron. This may be wiring by A1 vapor deposition. Next, in the case shown in FIG. 5, a solder layer 6 is formed. By placing the insulating base 1 on a hot plate to melt the solder layer 6, and then placing the single crystal silicon substrate 7 forming the diaphragm chip on which the solder layer 14 is formed, on the insulating base 1. , in order to adhesively support the first adhesive part 4 and the second adhesive part 11 using the solder of both solder layers 6, 14 as an adhesive to provide airtightness, and to electrically connect to the strain gauge 8. conductor layer 3
Similarly, the upper solder layer 6 and the externally drawn electrode 12 are connected at the same time using the solder layers 6 and 14 to achieve the desired pressure.
This is a vibration-electric conversion device.

In FIG. 5, the pressure introducing vibrator 101 is bonded, but it may be formed integrally when the insulator base 1 is made.

Further, 102 indicates a plurality of external conducting wires. When the converter of the present invention manufactured in this way is used as a detector in an automobile, for example, by introducing intake manifold pressure into the vibrator 101,
In addition to measuring pressure, if this converter is attached to the car body, the vibrations of the car body can be output, or if it is attached to the engine body, the vibrations of the engine body can be output at the same time. FIG. 6 shows the output waveform of the converter shown in FIG.

In the figure, the output ΔV1 is the output due to pressure change, and ΔV2 is the magnitude of vibration, and the frequency of vibration can be detected by measuring the vibration period t. Moreover, this converter can not only be used as a stand-alone pressure-only or vibration-only detector, but by changing the mass of the sensitive mass section 13, it can also be used as an accelerometer with high accuracy over a wide range. Needless to say. FIGS. 7A, B, and C show how the component ΔV1 due to pressure change and the vibration component V2 are separated.

7A is a detection circuit block, FIG. 7B is a pressure waveform, and FIG. 7C is a diagram showing a vibration waveform. In this way, when the device of the present invention is applied to automobile engine control, changes in the intake manifold pressure, which represents the amount of air supplied to the engine, have a very low frequency, while vibrations in the engine body due to explosions in the engine It consists of very high frequency components.

Output waveform (
Figure 6) consists of a pressure component of large undulations and a vibration component consisting of high frequency waves superimposed on the large undulations. If an abnormality in the engine's explosive state, such as knocking, occurs, a change in high frequency vibration components will occur. By processing the combined output waveform of this force and vibration with a computer, it is possible to form signals for adjusting ignition timing, fuel supply amount, etc. It goes without saying that the present invention is applicable not only to strain gauges formed by diffusion, but also to any type of strain-sensitive element formed on a diaphragm, such as vapor-deposited thin films, metal strain gauges, and other strain-sensitive elements.

Further, the silicon crystal plane used is not limited to the (100) plane. Further, it is appropriate that the sensitive mass portion 13 be formed at or near the center of the diaphragm 10, but this is not particularly limited. The sensitive mass can also be increased by attaching a weight to the solder layer 14 of the sensitive mass section 13 in FIGS. 3 and 4. Further, the sensitive mass portion may be formed on both sides of the diaphragm, or may be divided into a plurality of pieces. Further, a signal processing circuit, an amplifier circuit, etc. may be mounted on the insulator base 1. As described above, in the present invention, the diaphragm part deforms in accordance with the pressure to be measured, and the vibration of the diaphragm part itself transmitted from the support can be amplified by the sensitive mass element to deform the diaphragm part. As a result, even with the same strain-sensitive element, it is possible to obtain a composite output that takes into account both the pressure to be measured and the vibration change.Moreover, the sensitive mass element is combined with the first metal film in a predetermined pattern. In combination with the solder layer on this film, it can be easily and freely set on the diaphragm part, and therefore the device can be provided in a small size and at low cost.

[Brief explanation of the drawing]

1 and 2 are a plan view and a side sectional view showing an embodiment of an insulator base used in the conversion device of the present invention, and FIGS. 3 and 4.
The figure is a plan view and side sectional view showing an embodiment of the tire phragm chip used in the device of the present invention, FIG. 5 is a side sectional view showing the overall structure of an embodiment of the device of the present invention, and FIG. Output waveform diagram of an example device in the device, FIG. 7A, B
, C is an explanatory diagram showing one method of processing the detection output of the device of the present invention. 8... Strain gauge forming a perplexing strain element, 10...
...Thin-walled diaphragm, 10a...Support,
13,201... Sensitive mass portion forming a sensitive mass element.

Claims (1)

[Claims] 1. A silicon substrate integrally formed with a thin-walled diaphragm portion that responds to the pressure to be measured and a thick-walled support body;
A strain-sensitive element formed on a part of the main surface of the diaphragm part, a first metal film in a predetermined pattern formed substantially in the center of one main face of the diaphragm part, and a first metal film formed on a part of the main surface of the diaphragm part. a second metal film formed on the support on the same main surface side as the main surface and serving as an external extraction electrode for extracting a signal from the strain-sensitive element to the outside; the first metal film and the solder layer formed on the first metal film constitute a sensitive mass element that responds to vibrations of the diaphragm itself. A pressure/vibration-to-electrical conversion device, characterized in that the pressure to be measured and the vibration of the diaphragm itself are detected by the same strain-sensitive element.