JPH1019840A - Manufacture of co gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a CO gas sensor in which a gold wire can be bonded automatically in a state that a zironia element is inserted into, and fixed to, a ceramic case, whose mass productivity is excellent and whose bonding strength is stable. SOLUTION: A zirconia element 8 is inserted into, and fixed to, nearly the central part inside a cylindrical ceramic case 7, this assembly is sent to, and positioned in, a conductor bonding position by a component conveyance apparatus, a conductor is bonded to one side of the zirconia element 8, the conductor is cut, the cylindrical ceramic case 7 is then reversed, the above process is repeated again, and a conductor is bonded to the opposite side of the zirconia element 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a CO gas sensor in which a zirconia element is inserted into a cylindrical ceramic case, and more particularly to a method for manufacturing a CO gas sensor in which a method for connecting a conductor to a zirconia element is improved.

[0002]

2. Description of the Related Art A conventional CO gas sensor has a pair of gold wires on both sides of a zirconia element using an existing foot-operated spot welder before inserting and fixing the zirconia element substantially in the center of a cylindrical ceramic case. After welding, one of the gold wires was inserted into the cylindrical ceramic case, and one gold wire was inserted and fixed from the opening at both ends of the cylindrical ceramic case.

However, in the above-mentioned method, it is very difficult to handle the gold wire and to incorporate it into a cylindrical ceramic case, and no consideration has been given to a manufacturing method for automation corresponding to mass production. Japanese Patent Application Laid-Open No. 6-347431 discloses an example of applying wire bonding to manufacture a CO gas sensor. However, there is a problem that the conventional wire bonding cannot cope with the manufacture of a CO gas sensor. is there.

[0004] In detail, in the prior art, it is difficult to firstly join a gold wire to a zirconia element, and to handle and assemble the gold wire for inserting and fixing the zirconia element with the gold wire into a cylindrical ceramic case. However, no consideration has been given to the technology for mass production by automation, and the workability is poor due to manual assembly, and the bonding strength is also unstable, resulting in problems such as variations in product performance.

[0005]

According to the first and second aspects of the present invention, it is possible to automatically join conductors in a state where a zirconia element is inserted and fixed in a cylindrical ceramic case, and mass production is possible. An object of the present invention is to provide a method for producing a CO gas sensor having excellent bonding properties and stable bonding strength.

[0006]

The present invention is characterized in that a zirconia element is inserted into a cylindrical ceramic case, a conductor is connected to the zirconia element, and a catalyst is filled on both sides of the zirconia element. The present invention relates to a method for manufacturing a CO gas sensor.
Further, according to the present invention, a zirconia element having electrodes formed on both sides is inserted and fixed in a cylindrical ceramic case, a catalyst is filled in chambers on both sides thereof, and both ends are sealed with a porous ceramic plate. In a method of manufacturing a CO gas sensor in which a lead wire connected to the zirconia element is drawn out of the ceramic plate and a heater for heating is attached to the outer periphery of the cylindrical ceramic case, the zirconia element is disposed substantially in the cylindrical ceramic case. After inserting and fixing it in the center, sending it to the wire bonding position with the component transfer device and positioning it, joining the wire to one side of the zirconia element, cutting the wire, inverting the cylindrical ceramic case, and again A method for manufacturing a CO gas sensor, comprising repeating the above steps and joining a conducting wire to a zirconia element on the opposite side to the above. To.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A CO gas sensor according to the present invention is:
For example, a zirconia element provided with a pair of electrodes on both side surfaces is inserted and fixed at a substantially central portion in a cylindrical ceramic case, and two chambers are longitudinally inserted from both end surfaces of the cylindrical ceramic case into the cylindrical ceramic case. After that, a conductor is automatically joined to the zirconia element, then one of the chambers is filled with particles of a catalyst for oxidizing a combustible gas containing CO gas, and the other chamber is filled with a combustible gas other than CO gas. The catalyst particles are oxidized, and both ends of the cylindrical ceramic case are sealed with a porous ceramic plate, and a lead wire having a tip joined to the electrode of the zirconia element is drawn from the porous ceramic plate. It is obtained by attaching a heater for heating to the outer periphery of the cylindrical ceramic case.

The present invention seeks to improve the workability in a method of manufacturing a CO gas sensor as described above, particularly by automatically connecting a conductor to an electrode provided on a zirconia element. In the present invention, it is preferable to use a gold wire as the conductive wire. The zirconia element, the cylindrical ceramic case, and the like used in the present invention are known in the art and are not particularly limited. The cylindrical ceramic case is not particularly limited as long as it is cylindrical, but is preferably cylindrical in terms of manufacture and handling. The zirconia element to be inserted into the cylindrical ceramic case is not limited, but it is preferable to use a zirconia element formed in a disk shape.

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a means for bonding a gold wire to a zirconia element. A component transport device 1 includes a component positioning jig 2, a component holding mechanism 3, a gold wire bonding capillary 4, an electric torch 5, and a gold wire. A zirconia element is inserted and fixed in a cylindrical ceramic case, and a heater for heating is mounted on the outer periphery.
After positioning the gas sensor assembly (details are shown in FIG. 4) 11, the gold wire 10 is automatically connected to the electrode formed on the zirconia element.

FIGS. 2 (a) and 2 (b) are cross-sectional views showing the bonding state of the gold wires, and show the procedure for bonding the gold wires 10a and 10b. 2A and 2B, a CO gas sensor assembly 11 is a cylindrical ceramic case 7 and a zirconia element 8 having electrodes formed on both side surfaces.
And a heater 9 for heating.

FIG. 3 is a cross-sectional view of a CO gas sensor obtained according to an embodiment of the present invention. A zirconia element 8 stabilized with yttria (Y ₂ O ₃ ) is inserted into a substantially central portion of a cylindrical ceramic case 7. Fixed, zirconia element 8
Are bonded to lead pins 12a and 12b for extracting electric signals, respectively. Further, a heating heater 9 mounted on the outer periphery of the cylindrical ceramic case 7 serves to supply electric power. Are welded to the lead pins 13a and 13b. The inside of the cylindrical ceramic case is filled with a catalyst A14 and a catalyst B15 around the zirconia element 8, respectively, and sealed with a lid A16 and a lid B17 of a porous ceramic plate. Here, the lead pins 12a, 12b and 13a and 13b are previously inserted into the molded mounter 18, and after the gold wires 10a and 10b and the heater 9 are welded, respectively, The thermocouple 19 is assembled in the catalyst A14, and the cap 20 is attached to form a CO gas sensor.

FIG. 4 is a partially sectional perspective view of a CO gas sensor assembly for performing gold wire bonding. As described above, the CO gas sensor assembly 11 includes the cylindrical ceramic case 7, zirconia elements 8 having electrodes formed on both side surfaces, and a heater 9 for heating.

[0013]

Embodiments of the present invention will be described below. As shown in FIG. 2A, the CO gas sensor assembly 11 first
After the upper part of the component positioning jig 2a is brought into contact with the zirconia element 8 on the catalyst B filling side, it is sent to the gold wire bonding position by the component transport device 1 shown in FIG. After the CO gas sensor assembly 11 stops at the bonding position, the component holding mechanism 3
Then, the capillary 4 for gold wire bonding is lowered, and the gold wire 1 is placed on the catalyst A-filled side of the zirconia element 8 by a thermosonic ball bonding method.
0a is joined. At this time, the zirconia element 8 can be prevented from dropping from the cylindrical ceramic case 7 by the pressing force of the capillary 4.

Next, the capillary 4 sends out a predetermined length of the gold wire 10a from the tip while ascending and stops, and the gold wire cutting mechanism 6 advances to cut the gold wire 10a and then retreats. With the above, the gold wire bonding to one side of the zirconia element 8 is completed, the component holding mechanism 3 moves up, and the component transporting apparatus 1 moves to the next step, and the CO gas sensor assembly 11 can be taken out. At this time, in the wire bonder, the electric torch 5 is made to approach the tip of the gold wire in a state in which the wire is being viewed from the tip of the capillary 4, and the gold wire is melted by electronic spark to form a ball for the next bonding.

A CO gas sensor assembly 11 having a first gold wire 10a joined to the catalyst A-filled side of the zirconia element 8
Is turned, and the gold wire 10a is positioned while passing through a hole provided at the center of the component positioning jig 2b as shown in FIG. 2 (b). At this time, the cylindrical ceramic case 7 is positioned with its lower end in contact with the stepped portion of the component positioning jig 2b. Hereinafter, the gold wire 1 on the opposite side goes through the same process as above.
0b is joined, and a series of gold wire joining steps are completed.

After completion of the gold wire bonding step, the catalyst A and the catalyst B are filled in a cylindrical ceramic case, and both ends of the cylindrical ceramic case are sealed with a porous ceramic plate.
In addition, a gold wire joined to a pair of electrodes provided on both sides of the zirconia element is drawn out from the hole of the porous ceramic plate, and then the gold wire and the tip of the heating heater are connected to a lead pin previously inserted into the mounter. After bonding, a thermocouple for adjusting the temperature of the heater for heating was incorporated into the catalyst, and a cap device was provided to obtain a CO gas sensor.

In the above embodiment, the zirconia element used was a composition obtained by molding and firing a composition containing 8 mol% of yttria as a stabilizer with respect to 92 mol% of zirconia. Catalyst A was a platinum-alumina catalyst and Catalyst B used a tin oxide catalyst. Further, a heater wound with an iron-chrome wire was used as a heater for heating.

[0018]

According to the present invention, the gold wire can be automatically joined while the zirconia element is inserted and fixed in the cylindrical ceramic case, and the mass productivity is excellent and the joining strength is stable. A CO gas sensor can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a means for bonding a gold wire to a zirconia element.

FIGS. 2A and 2B are cross-sectional views showing a bonding state of gold wires.

FIG. 3 is a cross-sectional view of a CO gas sensor obtained according to an embodiment of the present invention.

FIG. 4 is a partial cross-sectional perspective view of a CO gas sensor assembly that performs gold wire bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Component conveyance apparatus 2a, 2b Component positioning jig 3 Component holding mechanism 4 Capillary 5 Electric torch 6 Cutting mechanism 7 Cylindrical ceramic case 8 Zirconia element 9 Heater 10a, 10b Gold wire 11 CO gas sensor assembly 12a, 12b Lead pin 13a, 13b Lead pin 14 Catalyst A 15 Catalyst B 16 Lid A 17 Lid B 18 Mounter 19 Thermocouple 20 Cap

Claims (2)

[Claims] 1. A method for manufacturing a CO gas sensor, comprising inserting a zirconia element into a cylindrical ceramic case, connecting a conductive wire to the zirconia element, and then filling both sides of the zirconia element with a catalyst. 2. A zirconia element having electrodes formed on both sides is inserted and fixed in a cylindrical ceramic case, and the chambers on both sides are filled with a catalyst, and both ends are sealed with a porous ceramic plate. Then, a lead wire joined to the zirconia element is drawn out of the ceramic plate, and further, a method of manufacturing a CO gas sensor in which a heater for heating is attached to the outer periphery of the cylindrical ceramic case is provided. After inserting it into the part and fixing it, sending it to the wire bonding position with the component transfer device and positioning it, then join the wire to one side of the zirconia element,
After cutting the conductor, turn the cylindrical ceramic case over,
A method for manufacturing a CO gas sensor, comprising repeating the above steps to join a conducting wire to the zirconia element on the opposite side.