JP3487675B2 - Manufacturing method of mechanical quantity sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mechanical quantity sensor for detecting stress such as pressure, load and acceleration.

[0002]

2. Description of the Related Art Conventionally, in a thick film resistance type mechanical quantity sensor, as shown in FIG. 3, a conductive paste is applied on an insulating insulating substrate 6 made of a metal base material 4 and a crystallized glass 5 covering the surface thereof. After drying, a pair of electrodes 2 is formed by firing at high temperature, and then a resistance paste is applied between the electrodes 2 so as to connect them, dried, and then fired at high temperature to obtain a strain-sensitive resistor. It is produced by forming 1.

[0003]

In the mechanical quantity sensor, since it is necessary to solder the lead portion in order to connect the electrode to the external circuit, the conductive paste such as Ag-Pd system or Ag-Pt system is used. A paste containing silver is used. As described above, when a conductive paste containing silver is used, when the resistor is formed by firing, heat elutes silver in the resistor and oxidizes it, resulting in current noise characteristics and resistance value variation of the resistor. The problem was that

[0004]

According to the method of manufacturing a mechanical quantity sensor of the present invention, an electrode is formed by applying a conductive paste on an insulating substrate having a metal elastic body coated with crystallized glass, drying and firing. A second step of forming a strain-sensitive resistor by applying a resistance paste to a position that does not come into contact with the electrode, drying it, and baking it at a temperature lower than the baking temperature of the conductive paste; and A conductive paste is applied between the electrode and the strain-sensitive resistor, dried, and fired at a temperature lower than the firing temperature of the resistance paste to form a connection body that electrically connects the electrode and the strain-sensitive resistor. It is characterized by including a third step. Further, on the insulating substrate coated with the crystallized glass metal elastic body, one of the conductive paste for electrodes and the resistance paste, after drying, the other paste at a position that does not contact the pattern coated with the paste A first step of simultaneously forming the electrode and the strain-sensitive resistor by applying, drying and firing, and applying and drying a conductive paste between the electrode and the strain-sensitive resistor at the firing temperature. The method is characterized by including a second step of firing at a lower temperature to form a connection body that electrically connects the electrode and the strain sensitive resistor. Further, the conductive paste for forming the connection body contains gold. Further, the crystallized glass is Si
O ₂ : 7 to 33% by weight, B ₂ O ₃ : 5 to 31% by weight, Mg
O: 16 to 50% by weight, CaO: 0 to 20% by weight, Ba
O: 0 to 50% by weight, La ₂ O ₃ : 0 to 40% by weight, MO
₂ (M is at least one selected from the group consisting of Zr, Ti and Sn): 0 to 5% by weight, and P ₂ O ₅ : 0
.About.5% by weight.

[0005]

In the method of the present invention, after the strain sensitive resistor is formed, the connection body which is in contact with the strain sensitive resistor is formed, so that the elution of silver to the strain sensitive resistor can be suppressed. Furthermore, since it is fired at a lower temperature than the strain-sensitive resistor paste, the diffusion of silver into the strain-sensitive resistor is reduced,
The current noise of the sensor circuit is reduced and the characteristic variation of the strain sensitive resistor is reduced. Further, by using the gold-based conductive paste for the connecting body connecting the electrode and the resistor, the diffusion of silver into the resistor is reduced, and the current noise of the sensor circuit and the variation in the characteristic of the resistor are reduced.

[0006]

EXAMPLES The method of manufacturing the mechanical quantity sensor of the present invention will be specifically described below. (1) Insulating Substrate (a) Base Material The metal base material used in the present invention is enamel steel, stainless steel, silicon steel, nickel-chromium-iron, nickel-.
Various alloy materials such as iron, kovar, invar, and clad materials thereof are preferable. In particular, stainless steel SUS430 is most preferable from the viewpoint of adhesion with the insulating layer. Once the material is determined, the base material is processed into a cylindrical shape, plate shape (including foil shape), etc. by machining, etching, laser processing, etc., depending on the size of the load and the application. It After shaping, the surface of the substrate is degreased for the purpose of improving the adhesion to the insulating layer. Further, if necessary, the degreased surface is subjected to sandblasting, various kinds of plating such as nickel and cobalt, or thermal oxidation for forming an oxide coating layer.

(B) Insulating Layer As the insulating layer formed on the metal base material, a layer made of crystallized glass is selected. The crystallized glass layer is preferably made of alkali-free crystallized glass (eg, glass that precipitates a MgO-based crystal phase by firing) from the viewpoints of electrical insulation, heat resistance, and substrate strength.

As a method for coating the substrate with the crystallized glass, a spray method, a powder electrostatic coating method, an electrophoretic electrodeposition method and the like are preferable. However, when the substrate is a metal, the denseness of the coating and the electrical insulation property are obtained. From the viewpoints of the above, the electrophoretic electrodeposition method is most preferable. In this electrophoretic electrodeposition method, first, glass, alcohol and a small amount of water are put and crushed and mixed in a ball mill for about 20 hours to make the average particle diameter of the glass about 1 to 5 μm. The obtained slurry is put in an electrolytic cell and circulated. The metal substrate prepared as described above is dipped in this slurry to
The glass particles are attached to the surface of the metal base material by performing negative polarization at 00 to 400V. After drying this,
A crystallized glass layer is obtained by firing at 900 ° C. for 10 minutes to 1 hour. By this firing, the glass fine particles are melted, and the glass component and the metal substrate component are sufficiently interdiffused, so that a strong adhesion between the crystallized glass layer and the metal substrate can be obtained.

The following studies were conducted on the composition of this crystallized glass. SUS430 (100 mm x
100 mm × 0.5 mm), the glass particles having the composition numbers 1 to 44 shown in Tables 1 to 8 are electrophoretically electrodeposited on the surface of the substrate by the method described above, and then baked at 880 ° C. for 10 minutes. As a result, an insulating substrate having a 100 μm thick crystallized glassy layer formed on the surface of the base material was obtained. For these insulating substrates, various properties such as surface roughness such as surface roughness and waviness and heat resistance were measured. The surface roughness is measured with a Talysurf surface roughness meter, and a surface center line average roughness R _a.
The waviness was defined as the maximum value R _max of the difference between the ridge and the valley of the undulation on the surface. Regarding the heat resistance, the sample was placed in an electric furnace at 850 ° C. for 10 minutes, then taken out of the furnace and spontaneously cooled for 30 minutes. A spalling test was repeated, and the state of cracking and peeling of the sample was examined. The presence or absence of cracks was determined by immersing the sample in the red ink, wiping off the ink on the surface of the sample, and visually observing whether or not the red ink remained on the surface of the sample. In the table, ○, △, and × are the ones in which ○ is no abnormality after a spalling test for 10 cycles or more, Δ is the abnormality in 5 to 9 cycles, and × is the abnormality in 4 cycles or less. Indicates what has occurred.
Adhesion was measured by conducting a bending test on an insulating substrate, and x when the crystallized glass layer was peeled off to expose the metal part, Δ when the metal part was partially exposed, and when the metal part was not exposed. ○
And A comprehensive evaluation was performed based on the above evaluations, and the results are shown by ◯, Δ, and ×.

No. 1 shown in Table 1 Nos. 1 to 8 are obtained by changing SiO ₂ and B ₂ O ₃ while keeping other components constant.

[0011]

[Table 1]

As is clear from these, as the content of SiO ₂ is increased, the heat resistance is improved, but the surface property and the adhesion are deteriorated. On the contrary, when the amount of B ₂ O ₃ is increased, the surface property and the adhesion are improved, but the heat resistance is decreased. Taking these into consideration, the composition ratio of SiO ₂ is 7 to 33% by weight, B ₂ O
The composition ratio of ₃ is preferably 5 to 31% by weight.

No. 1 shown in Table 2 9 to 15 are SiO ₂ /
B ₂ O ₃ was made almost constant and the amount of MgO was changed.

[0014]

[Table 2]

If the amount of MgO added exceeds 50% by weight,
Crystals tend to precipitate and easily crystallize when the glass melts. Therefore, it is difficult to obtain a homogeneous glass, and the surface roughness becomes large. The amount of MgO has a correlation with crystallinity, and if it is less than 16% by weight, crystal precipitation is insufficient and heat resistance is poor. Therefore, the composition ratio of MgO is preferably in the range of 16 to 50% by weight.

No. 1 shown in Table 3 16 to 19 are SiO ₂
/ B ₂ O ₃ is kept substantially constant, and the amount of CaO is changed. No. shown in Table 4 20-24 are also BaO
The amount is changed. In addition, No. Two
Similarly, in Nos. 5 to 29, the amount of La ₂ O ₃ was changed.

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

When the amount of CaO added exceeds 20% by weight, the surface properties are deteriorated, which is not preferable. Therefore, CaO
The addition amount of is preferably 0 to 20%. When the added amount of BaO exceeds 50% by weight, heat resistance and adhesion are deteriorated, which is not preferable. Therefore, the addition amount of BaO is 0 to
50% is preferable. When the amount of La ₂ O ₃ added exceeds 40% by weight, heat resistance deteriorates, which is not preferable. Therefore, L
The addition amount of a ₂ O ₃ is preferably 0 to 40%.

No. 1 shown in Tables 6-8. 30-44 is that each changing the added amount of _{ZrO 2, TiO 2, SnO 2} , P 2 O 5, ZnO.

[0022]

[Table 6]

[0023]

[Table 7]

[0024]

[Table 8]

ZrO ₂ , TiO ₂ , SnO ₂ , P ₂ O ₅ , Z
nO and the like can be added up to 5% by weight.

Next, a method of manufacturing the mechanical quantity sensor of the present invention will be described. [Example 1] As shown in FIG. 1, a diameter of 40 mm and a thickness of 1
No. 1 in Table 1 was obtained after performing pretreatments such as degreasing, washing with water, pickling, washing with water, nickel plating, and washing on the metal base material 4 made of disc-shaped stainless steel SUS430 of 00 μm. The surface of the base material 4 was coated with the glass particles by immersing in a slurry composed of glass particles having the composition shown in 7 and applying a DC voltage between the counter electrode and the base material 4. Then, from room temperature to 88
The temperature was raised to 0 ° C. over 2 hours, and the temperature was maintained for 10 minutes to carry out baking to obtain an insulating substrate 6 having a 70 μm thick insulating layer 5 made of crystallized glass on the surface of the base material 4. FIG. 2 is a pattern diagram of the mechanical quantity sensor used in the examination of the present embodiment. By using this pattern, a mechanical quantity sensor including a strain sensitive resistor 1, a pair of curved electrodes 2, and a T-shaped connecting body 3 connecting the strain sensitive resistor 1 and the electrode 2 is formed on the same insulating substrate 6. Two pieces were formed on the top. First, a pair of electrodes 2 is formed by applying Ag-Pd-based conductive paste in a pattern shown in FIG. 2A on the surface of the obtained insulating substrate 6, drying the paste, and baking the paste at 850 ° C. did. Next, as also shown in FIG. 2A, a RuO ₂ -based resistance paste is applied between the electrodes 2 so as not to come into contact with the electrodes 2 and dried.
The resistor 1 was formed by firing at 0 ° C. Finally, apply a gold-based conductive paste to the pattern shown in FIG.
A mechanical sensor was obtained by drying and firing at 500 ° C., which is lower than the firing temperature of the resistor, to form a connector 3 that electrically connects the resistor 1 and the electrode 2.

[Embodiment 2] Insulating substrate 6 similar to that of Embodiment 1
On the surface of, the Ag for the electrode 2 in the same pattern as in Example 1
-Pd-based conductive paste is applied and dried, and then a RuO ₂ -based resistance paste is applied in the same pattern as in Example 1,
After drying, these were baked at 700 ° C. to simultaneously form the resistor 1 and the electrode 2. Next, a gold-based conductive paste was applied to the same pattern as in Example 1, dried, and fired at 500 ° C. to form the connector 3 to obtain a mechanical quantity sensor.

[Embodiment 3] Insulating substrate 6 similar to that of Embodiment 1
After the RuO ₂ -based resistance paste was applied and dried on the surface of Example 1 in the same pattern as in Example 1, and the Ag-Pd-based conductive paste for electrodes was applied and dried in the same pattern as in Example 1, 700 The resistor 1 and the electrode 2 were simultaneously formed by firing at a temperature of ℃. Next, a gold-based conductive paste was applied to the same pattern as in Example 1, dried, and baked at 500 ° C.
By forming the connection body 3, a mechanical quantity sensor was obtained.
This is a manufacturing method of the mechanical quantity sensor of the third embodiment.

[Comparative Example] On the surface of an insulating substrate 6 composed of the same metal base material 4 and insulating layer 5 as in Example 1, an electrode pattern having a shape in which the electrode 2 and the connecting body 3 in Example 1 were integrated was Ag. -After applying Pd-based conductive paste and drying,
The pair of electrodes was formed by firing at 800 ° C. Next, a resistance paste was applied between the electrodes in the same pattern as in Example 1, dried, and baked at 700 ° C. to form the resistor 1, thereby obtaining a mechanical quantity sensor.

With respect to these sensors, the resistance value and current noise at 25 ° C. were measured for 50 each using a digital multimeter TR6871 manufactured by Advantest Corporation. Regarding the resistance value, the variation was obtained. The variation was ½ of the difference between the maximum value and the minimum value. The results are shown in Table 9.

[0031]

[Table 9]

As can be seen from Table 9, the sensors of Examples 1 to 3 have better resistance variation and noise characteristics than the Comparative Example. This is resistor 1
It is considered that this is because the electrode 2 and the electrode 2 are not directly connected to each other by interposing the connector 3 containing no silver therebetween, so that the elution of silver in the electrode 2 during firing to the resistor 1 is suppressed. . Further, after the resistor 1 is formed, the connecting body 3 connected to the resistor 1 is formed by firing at a temperature lower than the firing temperature at which the resistor 1 is formed. In the above, since the fluidity of the composition in the resistor 1 is lowered, it is considered that the diffusion of silver in the resistor 1 is suppressed.

[Embodiment 4] In a manufacturing method similar to that of Embodiment 1, a mechanical quantity sensor using the same Ag-Pd-based paste for forming the electrode 2 as the conductive paste for forming the connecting body 3 was prepared. . [Embodiment 5] In the same manufacturing method as in Embodiment 2, a conductive paste for forming the connecting body 3 was formed with the same A as for forming the electrode 2.
A mechanical sensor using a g-Pd-based paste was manufactured. [Sixth Embodiment] In the same manufacturing method as in the third embodiment, the same A as that for forming the electrode 2 is added to the conductive paste for forming the connection body 3.
A mechanical sensor using a g-Pd-based paste was manufactured. With respect to the mechanical quantity sensors manufactured by these manufacturing methods, 50 resistance values and current noises at 25 ° C. were measured in the same manner as in Examples 1 to 3. Regarding the resistance value, the variation was obtained. The variation was ½ of the difference between the maximum value and the minimum value. The results are shown in Table 10.

[0034]

[Table 10]

According to this, although the effect is slightly smaller than those of Examples 1 to 3 using the gold-based conductive paste for forming the connection body 3, both the resistance value and the current noise are greatly improved as compared with the comparative example. You can see that it was done. According to this result, the effect of forming the strain sensitive resistor 1 by firing and then firing at a temperature lower than the firing temperature to form the connection body 3 connected to the strain sensitive resistor 1 is confirmed.

[0036]

As described above, according to the present invention, it is possible to manufacture a mechanical quantity sensor having a small variation in resistance value and an excellent noise characteristic.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a mechanical quantity sensor according to a manufacturing method of an embodiment of the present invention.

FIG. 2 is a plan view showing a pattern of electrodes, strain sensitive resistors, etc. of the mechanical quantity sensor used in the embodiment of the present invention, FIG.
Shows a pattern of electrodes and strain sensitive resistors, and (b) shows a pattern in which a connecting body is further formed.

FIG. 3 is a vertical sectional view of a mechanical quantity sensor according to a manufacturing method of a comparative example.

[Explanation of symbols]

1 resistor 2 electrodes 3 connection 4 metal base materials 5 insulating layers 6 insulating substrate

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaki Ikeda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-6-137979 (JP, A) JP-A-3- 63537 (JP, A) JP 59-18669 (JP, A) JP 2-223836 (JP, A) JP 6-137805 (JP, A) JP 55-55575 (JP, A) JP-A-48-102258 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 29/84 C23C 24/08 G01B 7/16 G01L 1/18 G01P 15/12

Claims (4)

(57) [Claims] 1. A first step of forming an electrode by coating, drying and firing a conductive paste on an insulating substrate having a metal elastic body coated with crystallized glass, and a resistance paste at a position not in contact with the electrode. A second step of forming a strain-sensitive resistor by applying, drying and firing at a temperature lower than the firing temperature of the conductive paste, and applying a conductive paste between the electrode and the strain-sensitive resistor, A method for manufacturing a mechanical quantity sensor, comprising a third step of drying and firing at a temperature lower than a firing temperature of the resistance paste to form a connection body for electrically connecting the electrode and the strain sensitive resistor. 2. An insulating substrate having a metal elastic body coated with crystallized glass is coated with either one of a conductive paste for electrodes and a resistance paste and dried, and then placed at a position not in contact with the pattern coated with the paste. A first step of simultaneously forming the electrode and the strain sensitive resistor by applying the other paste, drying and firing, and applying and drying a conductive paste between the electrode and the strain sensitive resistor, A method of manufacturing a mechanical quantity sensor comprising a second step of firing at a temperature lower than the firing temperature to form a connection body for electrically connecting the electrode and the strain sensitive resistor. 3. The method for manufacturing a mechanical quantity sensor according to claim 1, wherein the conductive paste for forming the connection body contains gold. 4. The crystallized glass is SiO ₂ : 7 to 3
3% by weight, B ₂ O ₃ : 5 to 31% by weight, MgO: 16 to 5
0% by weight, CaO: 0 to 20% by weight, BaO: 0 to 50
% By weight, La ₂ O ₃ : 0 to 40% by weight, MO ₂ (M is Z
at least one selected from the group consisting of r, Ti and Sn): 0 to 5% by weight, and P ₂ O ₅ : 0 to 5% by weight
The method for manufacturing a mechanical quantity sensor according to claim 1 or 2, comprising: