JP3967788B2 - Capacitive pressure sensor - Google Patents

Description

本表より、実施例１，２の静電容量型圧力センサは、比較例１，２の静電容量型圧力センサに比べて初期値を小さくして感度を高められるのが分る。特にリード線部６の幅寸法を小さくしただけの比較例２の静電容量型圧力センサは、比較例１の静電容量型圧力センサに比べれば感度を高められるものの、実施例１，２の静電容量型圧力センサと比べると感度が低いのが分る。
【００２０】
なお本実施例では、接合パターン３をガラス封着パターンにより形成したが、接合パターン３はセラミックス，樹脂等により形成することができる。また、第１のパターン１２と第２のパターン１３とを別々の材質により形成してもよい。
また、本実施例では、リード線部６の幅寸法を基準容量電極５に接続されたリード線部８の幅寸法よりも小さくしたが、リード線部６の幅寸法を任意に選択した寸法に設定しても構わない。
【００２１】
【発明の効果】
本発明によれば、主容量電極に接続されたリード線部と交差しないように第２のパターンを形成するので、リード線部と対向電極とが誘電率の高い第２のパターンを介して対向する部分がなくなり、リード線部と対向電極との間の容量を小さくでき、コンデンサ感度の低下を抑制できる。
【図面の簡単な説明】
【図１】 （Ａ）及び（Ｂ）は本実施例の静電容量型圧力センサの平面図及び側面図である。
【図２】 本実施例の静電容量型圧力センサの概略断面図である。
【図３】 本実施例の静電容量型圧力センサのベース基板を示す平面図である。
【図４】 本実施例の静電容量型圧力センサのダイアフラム基板を示す平面図である。
【図５】 本実施例の静電容量型圧力センサの接合パターンを示す平面図である。
【図６】 本実施例の静電容量型圧力センサを製造する際のガラス封着材料パターンを示す平面図である。
【図７】 従来の静電容量型圧力センサの概略断面図である。
【符号の説明】
１ ベース基板
２ダイアフラム基板
３ 接合パターン
４ 主容量電極
５ 基準容量電極
６，８ リード線部
１０ 対向電極
１２ 第１のパターン
１３ 第２のパターン
１３ａ 切欠き部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacitance type pressure sensor that measures a pressure value by a change in capacitance.
[0002]
[Prior art]
As a capacitance type pressure sensor, an annular main capacitance electrode formed on the base substrate with an interval, an arc-shaped reference capacitance electrode formed on the outer side of the main capacitance electrode, and an opposing formed on the diaphragm substrate A substrate in which a base substrate and a diaphragm substrate are bonded via a bonding pattern made of an insulating material so that the electrodes face each other is known. In this type of capacitive pressure sensor, pressure is applied from the outside, the diaphragm substrate is bent, and the distance between the main capacitor electrode and the counter electrode changes, so that the gap between the main capacitor electrode and the counter electrode is changed. The capacitance changes. When measuring pressure using this capacitance type pressure sensor, the capacitance that changes between the main capacitance electrode and the counter electrode, and the reference capacitance between the reference capacitance electrode and the counter electrode, The pressure value is calculated based on However, in such a capacitance type pressure sensor, when a pressure is applied to the diaphragm substrate, the distance between the reference capacitance electrode and the counter electrode changes slightly, and the reference capacitance electrode and the counter electrode are changed. The reference capacitance in between also changes. For this reason, there is a limit to increasing the measurement accuracy of the pressure value.
[0003]
Therefore, as shown in the schematic cross-sectional view of FIG. 7, the inventor has a first pattern 102 that is located outside the reference capacitance electrode 101 and surrounds the reference capacitance electrode 101, a main capacitance electrode 103, and a reference capacitance electrode. A bonding pattern having a second pattern 107 that is located between the reference capacitor electrode 101 and the counter electrode 104 and that suppresses a change in the distance between the base substrate 105 and the diaphragm substrate 106. It was proposed to use (Japanese Patent Application No. 7-218777). FIG. 7 is a schematic diagram showing a cross section of the capacitive pressure sensor at the position of the lead wire portion 108 of the main capacitance electrode 103. The annular main capacitance electrode 103 and the main capacitance electrode 103 are connected to the pressure sensor. The lead wire portion 108 extending outward is divided by a broken line L.
[0004]
[Problems to be solved by the invention]
When the capacitance type pressure sensor having the configuration of FIG. 7 was actually manufactured and the characteristics were examined, it was found that the sensitivity of the pressure sensor was lower than the theoretical value. As a result of searching for the cause, it has been found that the sensitivity of the pressure sensor is lowered when the second pattern 107 of the bonding pattern intersects the lead wire portion 108 of the main capacitance electrode 103. The sensitivity of the pressure sensor, that is, the sensitivity of the main capacitance is defined as (capacitance change ΔCn at a certain pressure) / (initial value Co). This initial value is the sum of the main capacitance Cm generated between the main capacitance electrode 103 and the counter electrode 104 and the capacitance Cx generated between the lead wire portion 108 and the counter electrode 104 when no pressure is applied. It can be regarded as (Cm + Cx). However, since an insulating material such as a glass material forming the second pattern 107 has a high dielectric constant, the capacitance Cx increases at the portion where the second pattern 107 intersects the lead wire portion 108, and as a result, the above sensitivity is achieved. The denominator of the equation increases and the sensitivity of the pressure sensor decreases.
[0005]
The objective of this invention is providing the electrostatic capacitance type pressure sensor which can suppress that the sensitivity of a pressure sensor falls.
[0006]
Another object of the present invention is to provide a capacitance type pressure sensor that can suppress a decrease in sensitivity and that can vent the gas inside the second pattern.
[0007]
[Means for Solving the Problems]
The present invention provides a main capacitance electrode, a lead wire portion connected to the main capacitance electrode, a reference capacitance electrode formed outside the main capacitance electrode, and a lead wire portion connected to the reference capacitance electrode. A base substrate formed on the surface of the substrate, a diaphragm substrate provided on one surface with a counter electrode facing the main capacitor electrode, the lead wire portion, and the reference capacitor electrode at a predetermined interval, and the base substrate and the diaphragm substrate And a bonding pattern made of an insulating material which is disposed between the two substrates and forms a predetermined interval. The bonding pattern is located outside the reference capacitance electrode and surrounds the reference capacitance electrode. A second pattern which is located between the pattern, the main capacitor electrode and the reference capacitor electrode and suppresses a change in the distance between the base substrate and the diaphragm substrate between the reference capacitor electrode and the counter electrode; Directed to the improved capacitive pressure sensor being.
[0008]
In the present invention, the second pattern is formed so as not to cross the lead wire portion connected to the main capacitor electrode. With this configuration, there is no portion where the lead wire portion and the counter electrode are opposed to each other via the second pattern having a high dielectric constant, and the capacitance Cx between the lead wire portion and the counter electrode can be reduced. The decrease in sensitivity can be suppressed.
[0009]
The main capacitance electrode can be formed in an annular shape, and the reference capacitance electrode can be formed in an arc shape so as not to cross the lead wire portion connected to the main capacitance electrode. The bonding pattern can be formed of an insulating material mainly composed of glass. In this case, the second pattern may be formed in an annular shape with a notch provided with a notch portion through which the lead wire portion connected to the main capacitor electrode does not come into contact with the second pattern. If it does in this way, the notch part of the 2nd pattern can serve as the gas vent passage inside the 2nd pattern. Without such a passage, the degree of deformation of the diaphragm portion when pressure is applied to the diaphragm portion is deteriorated.
[0010]
The width dimension of the lead wire portion connected to the main capacitance electrode is preferably smaller than the width dimension of the lead wire portion connected to the reference capacitance electrode. Since the second pattern and the lead wire portion do not cross each other, the capacitance Cx is reduced. However, if the width dimension of the lead wire portion facing the counter electrode is further reduced, the capacitance Cx is further reduced. Therefore, sensitivity further increases. However, if the width dimension becomes too small, the resistance of the lead wire portion increases, and tan δ determined by the main capacitance and the resistance value of the lead wire portion becomes excessively larger than necessary, resulting in an increase in energy loss. Therefore, it is necessary to set the width dimension of the lead wire portion so small that tan δ does not become larger than necessary. Specifically, when the width dimension of the lead wire portion connected to the main capacitance electrode is 0.4 to 0.6 mm, the sensitivity can be increased and tan δ is not excessively increased.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. 1A and 1B are a plan view and a side view of a capacitive pressure sensor as an example of an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the capacitive pressure sensor of the present embodiment. It is the figure represented roughly. As shown in these drawings, the capacitive pressure sensor of the present embodiment has a structure in which a base substrate 1 and a diaphragm substrate 2 are coupled via a bonding pattern 3. Since the thickness of the bonding pattern 3 is extremely thin, the thickness of the bonding pattern 3 and the dimension between the base substrate 1 and the diaphragm substrate 2 are exaggerated in the schematic diagram of FIG.
[0012]
The base substrate 1 is made of ceramics and has a shape close to a cylinder having a cut end face 1a on the side. A signal circuit (not shown) is formed on the surface 1b of the base substrate 1 opposite to the surface facing the diaphragm substrate 2. As shown in detail in the plan view of FIG. 3, the main capacitor electrode 4 and the reference capacitor electrode 5 are formed on the surface of the base substrate 1 facing the diaphragm substrate 2 with a radial interval. The main capacitance electrode 4 is formed by screen printing using Au paste (gold paste), and has a circular shape with a thickness of 0.7 μm. A part of the main capacitance electrode 4 is electrically connected to the main capacitance electrode terminal 7 by a lead wire portion 6. The width dimension of the lead wire portion 6 is smaller than the width dimension (1 mm) of the lead wire portion 8 connected to the reference capacitance electrode 5, and the main capacitance between the main capacitance electrode 4 and the counter electrode 10 is The tan δ determined by the resistance value including the resistance of the lead wire portion 6 is set so as not to be excessively large. In this example, the lead wire portion 6 has a width dimension of 0.4 to 0.6 mm. Have. The lead wire portion 6 has a length dimension of 5.4 mm.
[0013]
The lead wire portion 6 and the main capacitor electrode terminal 7 are simultaneously formed using Au paste when the main capacitor electrode 4 is formed. The gap S in the center of the main capacitance electrode 4 has a role of changing the electrostatic capacitance between the main capacitance electrode 4 and the counter electrode 10 more accurately in proportion to the pressure applied to the diaphragm substrate 2, and the diaphragm substrate 2 Even if it is strongly pressed, it plays a role of preventing the counter electrode 10 from coming into contact with the main capacitance electrode 4 and short-circuiting. The reference capacitance electrode 5 is formed by screen printing using Au paste in the same manner as the main capacitance electrode 4 and has a thickness of 0.7 μm. The reference capacity electrode 5 has an arc shape that partially surrounds the main capacity electrode 4 concentrically with the main capacity electrode 4 so as not to intersect the lead wire portion 6. One end of the reference capacitance electrode 5 is connected to the reference capacitance electrode terminal 9 by a lead wire portion 8. The reference capacitance electrode terminal 9 is also formed at the same time when the reference capacitance electrode 5 is formed. In practice, the patterns of the main capacitor electrode 4, the reference capacitor electrode 5, the lead wire portions 6 and 8, the main capacitor electrode terminal 7, and the reference capacitor electrode terminal 9 are formed simultaneously. The main capacitor electrode terminal 7 and the reference capacitor electrode terminal 9 are electrically connected to a signal circuit formed on the surface 1b of the base substrate 1 through connection portions C1 and C2 formed on the cut end surface 1a of the base substrate 1. (FIG. 1).
[0014]
Diaphragm substrate 2 is made of ceramics and has a disk shape with a thickness of 0.46 mm. On the surface of the diaphragm substrate 2 facing the base substrate 1, a counter electrode 10 is formed as shown in detail in the plan view of FIG. The counter electrode 10 is formed by screen printing using Au paste and has a thickness of 0.7 μm. The counter electrode 10 is formed in a circular shape so as to face the main capacitor electrode 4, the lead wire portion 6 and the reference capacitor electrode 5 formed on the base substrate 1 with a predetermined interval. A connection terminal 11 protrudes from a part of the counter electrode 10. The counter electrode 10 and the connection terminal 11 are formed simultaneously by a single screen printing. The connection terminal 11 is electrically connected to a signal circuit formed on the surface 1b of the base substrate 1 through a connection portion C3 formed on the cut end surface 1a of the base substrate 1 (FIG. 1).
[0015]
The bonding pattern 3 is formed of an insulating material (bonding material) mainly composed of glass, and has a thickness of 10 to 15 μm. The bonding pattern 3 has a first pattern 12 and a second pattern 13 as shown in detail in the plan view of FIG. The first pattern 12 is formed in a shape along the outline of the base substrate 1 so as to be located outside the reference capacitance electrode 5 so as to surround the reference capacitance electrode 5 and cross the two lead wire portions 6 and 8. Has been. Moreover, the 1st pattern 12 is formed in the shape where the inner diameter part 12a and the outer diameter part 12b were connected by the some connection pattern part 12c .... With such a shape, it is possible to prevent the occurrence of voids (cracks) in the bonding pattern when the bonding pattern is formed.
[0016]
The second pattern 13 is located between the main capacitance electrode 4 and the reference capacitance electrode 5 and the distance between the base substrate 1 and the diaphragm substrate 2 between the reference capacitance electrode 5 and the counter electrode 10 changes. Is suppressed. The second pattern 13 has an annular shape with a notch provided with a notch portion 13a through which the lead wire portion 6 connected to the main capacitor electrode 5 does not come into contact with the second pattern 13. . The cutout portion 13 a also serves as a gas vent passage inside the second pattern 13. As shown in FIG. 2 and FIG. 6 showing the intersection of the glass sealing material pattern 3 ′ (pattern having the same shape as the bonding pattern 3) and the lead wire portion 6, the lead wire is provided. The portion where the portion 6 and the counter electrode 10 face each other via the bonding pattern 3 having a high dielectric constant is eliminated, the capacity between the lead wire portion 6 and the counter electrode 10 can be reduced, and the decrease in sensitivity of the pressure sensor can be suppressed. .
[0017]
The capacitance type pressure sensor of this example was manufactured as follows. First, a pattern of the main capacitor electrode 4, the reference capacitor electrode 5, the lead wire portions 6 and 8, the main capacitor electrode terminal 7 and the reference capacitor electrode terminal 9 is formed on the surface (facing surface) of the base substrate 1 facing the diaphragm substrate 2. To do. Next, a mask is applied on the opposite surface of the base substrate 1, and a glass sealing material pattern 3 'is formed using a glass sealing material melted by screen printing, as shown in FIG. Then, the diaphragm substrate 2 on which the counter electrode 10 is formed is overlapped on the base substrate 1 through the glass sealing material pattern 3 ', and the whole is put in a furnace to melt the glass sealing material pattern 3'. The substrate 1 and the diaphragm substrate 2 were joined to complete a capacitive pressure sensor.
[0018]
Next, the capacitive pressure sensors of Examples 1 and 2 and Comparative Examples 1 and 2 were prepared, and the initial value and sensitivity of each capacitive pressure sensor were measured. Here, the first embodiment is the capacitance type pressure sensor of the present embodiment described above. In the second embodiment, the width of the lead wire portion 6 is set to the same width (1 mm) as that of the lead wire portion 8 connected to the reference capacitor electrode 5, and the other structures are the same as those of the capacitive pressure sensor of the present embodiment. It is an electrostatic capacitance type pressure sensor which has. Further, in the capacitance type pressure sensor of Comparative Example 1, the width dimension of the lead wire portion 6 is the same as that of the lead wire portion 8 connected to the reference capacitance electrode 5 without providing the notch portion 13a (1 mm). The others are capacitive pressure sensors having the same structure as the capacitive pressure sensor of this embodiment. Further, the capacitive pressure sensor of Comparative Example 2 is a capacitive pressure sensor having the same structure as the capacitive pressure sensor of the present embodiment, except that the notch portion 13a is not provided. Table 1 shows the measurement results.
[0019]
[Table 1]

From this table, it can be seen that the capacitance type pressure sensors of Examples 1 and 2 can be improved in sensitivity by reducing the initial value as compared with the capacitance type pressure sensors of Comparative Examples 1 and 2. In particular, the capacitance type pressure sensor of Comparative Example 2 in which only the width of the lead wire portion 6 is reduced can increase the sensitivity as compared with the capacitance type pressure sensor of Comparative Example 1, but the capacitance pressure sensor of Examples 1 and 2 can be improved. It can be seen that the sensitivity is low compared to the capacitive pressure sensor.
[0020]
In this embodiment, the bonding pattern 3 is formed of a glass sealing pattern, but the bonding pattern 3 can be formed of ceramics, resin, or the like. Further, the first pattern 12 and the second pattern 13 may be formed of different materials.
Further, in this embodiment, the width dimension of the lead wire portion 6 is made smaller than the width dimension of the lead wire portion 8 connected to the reference capacitance electrode 5, but the width dimension of the lead wire portion 6 is arbitrarily selected. You can set it.
[0021]
【The invention's effect】
According to the present invention, the second pattern is formed so as not to intersect with the lead wire portion connected to the main capacitor electrode, so that the lead wire portion and the counter electrode face each other through the second pattern having a high dielectric constant. Therefore, the capacitance between the lead wire portion and the counter electrode can be reduced, and the decrease in capacitor sensitivity can be suppressed.
[Brief description of the drawings]
1A and 1B are a plan view and a side view of a capacitive pressure sensor according to the present embodiment.
FIG. 2 is a schematic cross-sectional view of a capacitive pressure sensor according to the present embodiment.
FIG. 3 is a plan view showing a base substrate of the capacitive pressure sensor of the present embodiment.
FIG. 4 is a plan view showing a diaphragm substrate of the capacitive pressure sensor of the present embodiment.
FIG. 5 is a plan view showing a bonding pattern of the capacitive pressure sensor according to the present embodiment.
FIG. 6 is a plan view showing a glass sealing material pattern when manufacturing the capacitive pressure sensor of this example.
FIG. 7 is a schematic cross-sectional view of a conventional capacitive pressure sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base substrate 2 Diaphragm substrate 3 Joining pattern 4 Main capacity electrode 5 Reference capacity electrodes 6, 8 Lead wire part 10 Opposite electrode 12 First pattern 13 Second pattern 13a Notch

Claims (3)

A main capacitance electrode, a lead wire portion connected to the main capacitance electrode, a reference capacitance electrode formed outside the main capacitance electrode, and a lead wire portion connected to the reference capacitance electrode on one surface A formed base substrate;
A diaphragm substrate provided on one surface with a counter electrode facing the main capacitor electrode, the lead wire portion and the reference capacitor electrode at a predetermined interval;
It is disposed between the base substrate and the diaphragm substrate, and includes a bonding pattern made of an insulating material that bonds the two substrates and forms the predetermined interval.
The junction pattern is located outside the reference capacitance electrode and surrounds the reference capacitance electrode, and the junction pattern is located between the main capacitance electrode and the reference capacitance electrode. A second pattern for suppressing a change in a distance between the base substrate and the diaphragm substrate between the counter electrode and the counter electrode ;
A capacitance type pressure sensor in which a main capacitance electrode terminal connected to the lead wire portion connected to the main capacitance electrode is formed outside the second pattern on the one surface ,
The capacitance-type pressure sensor, wherein the second pattern is formed so as not to intersect the lead wire portion connected to the main capacitance electrode on the one surface . An annular main capacitance electrode, a lead wire portion connected to the main capacitance electrode, an arc-shaped reference capacitance electrode formed outside the main capacitance electrode so as not to intersect the lead wire portion, and A ceramic base substrate having a lead wire portion connected to the reference capacitance electrode formed on one surface;
A ceramic diaphragm substrate provided on one surface with a counter electrode facing the main capacitor electrode, the lead wire portion, and the reference capacitor electrode at a predetermined interval;
It is arranged between the base substrate and the diaphragm substrate, and is composed of a bonding pattern made of an insulating material mainly composed of glass that bonds the two substrates and forms the predetermined interval.
The junction pattern is located outside the reference capacitance electrode, surrounds the periphery of the reference capacitance electrode, and intersects the two lead wires, and between the main capacitance electrode and the reference capacitance electrode And a second pattern that suppresses a change in the distance between the base substrate and the diaphragm substrate between the reference capacitance electrode and the counter electrode ,
A capacitance type pressure sensor in which a main capacitance electrode terminal connected to the lead wire portion connected to the main capacitance electrode is formed outside the second pattern on the one surface ,
The second pattern has an annular shape with a notch provided with a notch portion through which the lead wire portion connected to the main capacitance electrode does not come into contact with the second pattern, The capacitive pressure sensor is characterized in that the second pattern is formed so as not to intersect the lead wire portion connected to the main capacitance electrode on the one surface .   3. The width dimension of the lead wire portion connected to the main capacitor electrode is smaller than the width dimension of the lead wire portion connected to the reference capacitor electrode. 4. Capacitive pressure sensor.

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