WO2005085821A1 - 検出素子 - Google Patents
検出素子 Download PDFInfo
- Publication number
- WO2005085821A1 WO2005085821A1 PCT/JP2005/003674 JP2005003674W WO2005085821A1 WO 2005085821 A1 WO2005085821 A1 WO 2005085821A1 JP 2005003674 W JP2005003674 W JP 2005003674W WO 2005085821 A1 WO2005085821 A1 WO 2005085821A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- detection element
- heater
- bulk layer
- signal extraction
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
Definitions
- the present invention relates to a detection element for a gas sensor, and more particularly, to a detection element in which a bulk layer sensitive to a component in a gas and a heater pattern for heating the bulk layer to an operating temperature are formed on the same surface of a substrate.
- the detection element of the gas sensor is configured to heat a metal oxide formed on the surface of the ceramic substrate by a heater pattern provided on the back surface of the ceramic substrate.
- FIG. 3 shows the structure of a conventional detector.
- (A) is a plan view of the detection element, and (B) is a bottom view.
- FIG. 4 is a cross-sectional view taken along the line b_b shown in FIG.
- the conventional detection element 200 has a bulk layer 212 made of a metal oxide containing CuO as a main component. 0 2a is formed. On the back surface 202 b of the ceramic substrate 202, a heat pattern 204 covered with a glass overcoat layer 203 is formed. Therefore, the first signal extraction electrode 208 for detecting the electric signal of the bulk layer 212 and the second signal extraction electrode 211 are provided on the surface 202a of the ceramic substrate 202. I have.
- the first heater electrode 220 and the second heater electrode 222 that supply power to the heater pattern 204 are provided on the back surface 202 b of the ceramic substrate.
- the steps of forming the heater pattern 204 and the electrodes 208, 216, 222, and 222 on the substrate, and forming the respective electrode head lines It is necessary to separately perform a wire bonding step or the like for connecting the front and back of the ceramic substrate 202. For this reason, workability is poor and mass productivity is lacking.
- the bulk layer 2 12 is connected to the first and second signal extraction electrodes 2 08 and 2 16 formed on the surface 202 a of the ceramic substrate 202. .
- This connection has a structure in which both ends of the bulk layer 212 are adhered and fixed with bulk fixing pastes 230 and 232.
- both ends of the bulk layer are fixed as described above.
- Thermal stress occurs in layer 2 12, which may result in cracks or chips in bulk layer 2 12.
- a defect such as poor conduction of the detection element or an increase in the resistance of the element occurs, which hinders accurate detection of the concentration of carbon monoxide.
- An object of the present invention is to provide a detection element for a gas sensor which has good workability at the time of production and can reduce defects such as cracks and chips generated in a bulk layer due to heating by a light pattern.
- the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have arrived at an element structure in which a bulk layer is formed on an upper surface of a heater pattern covered with an insulator.
- the detecting element can be formed on the same surface of the substrate, so that the manufacturing of the detecting element can be performed by printing, wire bonding, or the like only on one surface of the substrate. Become good. Further, the inventors have found that this structure can reduce cracking and chipping of the bulk layer caused by the influence of thermal stress, and have completed the present invention.
- a heater pattern and first and second heater patterns connected to both ends of the heater pattern.
- a detection element comprising a wire connecting the upper element electrode and the second signal extraction electrode.
- the detection element of the present invention has a structure in which the heater pattern and the bulk layer are formed on the same surface of the substrate, and therefore is easy to manufacture and excellent in mass productivity.
- the detection element of the present invention employs a structure in which the bulk layer is fixed by bonding the lower surface of the bulk layer and the color bar coat layer, so that the bulk layer is heated by the hysteresis pattern. As a result, problems such as cracking and chipping of the bulk layer can be reduced.
- FIG. 1 is a plan view (A) and a bottom view showing an example of the detection element of the present invention.
- FIG. 2 is a cross-sectional view of the detection element of the present invention shown in FIG. 1 along the line aa.
- FIG. 3 is a plan view (A) and a bottom view (B) showing an example of a conventional detection element.
- FIG. 4 is a cross-sectional view of the conventional detection element shown in FIG. 3 along the line bb.
- 2 is a ceramic substrate, 2a is an upper surface, 2b is a lower surface, 3 is a glass overcoat layer, 4 is a heater pattern, 5 is an electrode, 6 is a first signal extraction electrode portion, 7 is a lower device electrode portion, and 8 is a lead.
- 12 is a bulk layer
- 14 is an upper element electrode
- 16 is a second signal extraction electrode
- 18 is a wire
- 20 is a first heater electrode
- 22 is a second heater electrode
- 24 , 26, 28, 30 are lead wires
- 32, 34 are wire bonding portions
- 100 is a detecting element.
- FIG. 1A is a plan view showing an example of the detection element of the present invention
- FIG. 1B is a bottom view thereof.
- FIG. 2 is a cross-sectional view taken along the line a_a shown in FIG.
- 100 is a detection element.
- Reference numeral 2 denotes a heat-resistant and insulating ceramic substrate such as alumina.
- a meandering heater pattern 4 is formed on the upper surface 2a of the ceramic substrate 2.
- the heat pattern 4 is made of an electric resistor thin film such as platinum formed by firing a pattern formed using a platinum paste or the like.
- Both ends of the heater pattern 4 are connected to a first heater electrode 20 and a second heater electrode 22 formed on the edge of the upper surface 2a of the ceramic substrate 2, respectively. Further, a lead wire 24 connected to an external power supply (not shown) is connected to the first heater electrode 20. A lead wire 26 connected to an external power supply (not shown) is connected to the second heater electrode 22. The heater pattern 4 is heated to a predetermined temperature by electric power supplied from an external power supply (not shown) through the lead wires 24 and 26.
- the upper surface of the heater pattern 4 is covered with a glass overcoat layer 3.
- the glass overcoat layer 3 functions as an insulating layer, and electrically insulates the heater pattern 4 from electrodes and the like described later.
- a lower device electrode portion 7 is formed on the upper surface of the glass cover coat layer 4.
- the lower element electrode part 7, the first signal extraction electrode 6 formed on the upper surface 2a of the ceramic substrate 2, and the lead part 8 are integrally formed to form the electrode 5, These are electrically connected to each other.
- the first signal extraction electrode section 6 is connected to a lead wire 28, and is connected to an external ammeter (not shown) via the lead wire 28.
- a bulk layer 12 is formed on the upper surface of the lower lower element electrode section 7.
- This bulk layer 12 is an oxide containing 15% by mass or less of an alkali metal such as Na.
- a paste is produced using a CuO powder containing 0.1 to 15% by mass of an Na element, and the paste is printed in an arbitrary shape, and then printed. For example, a method of obtaining a fired metal oxide thin film by firing at 500 ° C. is exemplified.
- This metal oxide fired body is known as a detecting element.
- An upper element electrode 14 is formed on the upper surface of the bulk layer 12.
- the upper element electrode 14 and the second signal extraction electrode 16 formed on the edge of the upper surface 2 a of the ceramic substrate 2 are electrically connected by wires 18.
- Reference numeral 32 denotes a wire bonding portion formed on the upper element electrode 14 using a wire fixing paste
- reference numeral 34 denotes a wire bonding portion formed on the second signal extraction electrode 16 using a wire fixing paste. It is.
- Reference numeral 30 denotes a lead wire connected to the second signal extraction electrode 16, and the external ammeter (not shown) is connected via the lead wire 30.
- the detection element 100 of the present invention can be manufactured as follows. First, in a printing process, (1) a heater pattern 4 is printed on one surface of a ceramic substrate 2 using a Pt paste, and (2) a glass overcoat layer 3 is printed using a glass paste. (3) The first signal extraction electrode part 6, the lead part 8, the lower element electrode part 7, the second signal extraction electrode 16, the first heater electrode 20, the second heater electrode using Au paste. 2 Form 2 by printing each. After each of the printing steps (1) to (3), the printed paste is dried and fired each time printing is performed. Commercially available Pt paste, glass paste, and Au paste can be used.
- the Pt paste for example, as the Pt paste, TR795 manufactured by Tanaka Kikinzoku Co., Ltd., glass paste
- the paste examples include AP5576 VE manufactured by Asahi Glass Co., Ltd.
- examples of the Au paste include TR159B and TR1442 manufactured by Tanaka Kikinzoku Co., Ltd.
- the sintering temperature and sintering time are based on a conventional method. Known methods can be used to print these pastes, but screen printing is preferred.
- the bulk layer 12 on which the upper element electrode 14 is formed is placed on the upper surface of the lower device electrode portion 7 formed by printing and firing, and the whole is fired.
- An electrode pattern is formed on the upper surface of the bulk layer 12 using an Au paste, and the upper element electrode 14 is formed by firing.
- Examples of a method of supplying the Au layer to the upper surface of the bulk layer 12 include a method of supplying the Au layer to the bulk layer 12 with a dispenser, a method of brushing, and a screen printing method. In consideration of mass productivity, supply by a dispenser that is easy to quantify is preferable.
- the wire 18 is bonded between the upper element electrode 14 and the second signal extraction electrode 16 using an Au wire fixing paste. Further, the lead wires 28, 30, 24, and 26 are bonded to the first signal extraction electrode section 6, the second signal extraction electrode 16, the first and second heater electrodes 20, 22, respectively. As a result, a detection element 100 is obtained.
- Au is preferable as the material of the wire 18.
- the thickness is preferably from 0.02 to 0.1 mm, more preferably from 0.02 to 0.03 mm from the viewpoint of preventing heat radiation.
- Predetermined power is supplied to the first heater electrode 20 and the second heater electrode 22 from an external power supply (not shown) connected to the lead wires 24 and 26.
- the heat radiation pattern 4 generates heat, and the bulk layer 12 is heated to the operating temperature (200 to 300 t).
- the power of the external power supply (not shown) connected to the lead wires 28 and 30 is It is applied to the lower element electrode section 7 and the upper element electrode 14 of the detection element 100.
- the electric resistance of the bulk layer 12 changes, and the current flowing between the first signal extraction electrode section 6 and the second signal extraction electrode 16 changes.
- an ammeter (not shown) the concentration of the carbon monoxide gas is measured.
- the detection element shown in FIG. 1 was manufactured. Platinum paste (TR 7905 made by Tanaka Kikinzoku Co., Ltd.) was applied to an alumina ceramic substrate (trade name A-4766 made by Kyocera) with a height of 5.08 mm, a width of 5.08 mm and a thickness of 38 mm. A meandering heater pattern was screen printed. This was baked at 950 ° C. for 10 minutes to form a heater pattern having a thickness of 8 m, a width of 200 mm, and a length of 42.25 mm.
- a glass paste (AP5556 VE manufactured by Asahi Glass Co., Ltd.) was screen-printed on the formed heater pattern and fired at 850 to form a glass overcoat having a thickness of 100 m. A coat layer was formed.
- a pulp layer having a length of 1.3 mm, a width of 1.3 mm and a thickness of 0.7 mm was formed on the upper surface of the lower device electrode portion.
- the bulk layer is obtained by compressing and molding a raw material containing 5 mass% of sodium tungstate in Cu powder, and sintering the compact at 725 ° C for 10 hours. Manufactured.
- the Au paste was printed on the upper surface of the bulk layer in the shape of an electrode, and fired at 65 ° to form an upper element electrode having a thickness of 1.3 mm ⁇ 1.3 mm and a thickness of 0.3 ⁇ . Finally, wire bonding was performed to obtain the detection element of the present invention.
- a power supply was connected to two lead wires respectively connected to the first and second heater electrodes, and an ohmmeter was connected to lead wires respectively connected to the first and second signal extraction electrodes.
- a voltage of 4.5 V was applied to the heater pattern, the temperature of the detector reached 260.
- the resistance value indicated by the ohmmeter was 120 ⁇ .
- this detector was exposed to air containing CO gas at a concentration of 300 ppm, the resistance changed to 1200 ⁇ , confirming that the detector was sensitive to CO.
- This detection element was subjected to a thermal shock resistance test. A voltage of 5 V was applied to the heater pattern, and the detection element was set to 350 ° C. In this state, the operation of applying voltage to the heater pattern for 30 seconds and then stopping for 30 seconds was repeated. When the application of voltage to the heater pattern was stopped, the temperature of the detection element was 30 ° C. 30 seconds after the stop. The above voltage application and stop were repeated 100 000 times. After that, when the bulk layer was visually observed, no cracks or the like had occurred.
- the conventional sensing element shown in FIG. 3 was manufactured according to the method shown in Example 1. Both ends of the bulk layer were fixed to the electrodes with the bulk layer fixed paste. The normal layer was 0.75 mm thick, 1.6 mm long x 2.8 mm wide.
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
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Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP2006510729A JPWO2005085821A1 (ja) | 2004-03-05 | 2005-02-25 | 検出素子 |
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JP2004-062217 | 2004-03-05 | ||
JP2004062217 | 2004-03-05 |
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WO2005085821A1 true WO2005085821A1 (ja) | 2005-09-15 |
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PCT/JP2005/003674 WO2005085821A1 (ja) | 2004-03-05 | 2005-02-25 | 検出素子 |
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WO (1) | WO2005085821A1 (ja) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6082953A (ja) * | 1983-10-14 | 1985-05-11 | Hitachi Ltd | 一酸化炭素ガス検出素子 |
JPH09138209A (ja) * | 1995-11-14 | 1997-05-27 | Figaro Eng Inc | ガス検出方法及びガス検出装置 |
JP2000338072A (ja) * | 1999-05-26 | 2000-12-08 | Mikuni Corp | 一酸化炭素センサ |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH1073552A (ja) * | 1996-08-29 | 1998-03-17 | Figaro Eng Inc | Coセンサ |
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2005
- 2005-02-25 JP JP2006510729A patent/JPWO2005085821A1/ja active Pending
- 2005-02-25 WO PCT/JP2005/003674 patent/WO2005085821A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6082953A (ja) * | 1983-10-14 | 1985-05-11 | Hitachi Ltd | 一酸化炭素ガス検出素子 |
JPH09138209A (ja) * | 1995-11-14 | 1997-05-27 | Figaro Eng Inc | ガス検出方法及びガス検出装置 |
JP2000338072A (ja) * | 1999-05-26 | 2000-12-08 | Mikuni Corp | 一酸化炭素センサ |
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