JP6710590B2 - Ceramic heater manufacturing method - Google Patents

Description

The present invention relates to a ceramic heater.

Conventionally, in a gas sensor using a solid electrolyte body such as an oxygen sensor, a ceramic heater is arranged to heat the solid electrolyte body (Patent Document 1).
As shown in FIG. 1, as the ceramic heater 100, one in which a heating resistor 141 made of a metal such as tungsten or molybdenum is embedded in a cylindrical ceramic substrate 102 made of alumina or the like extending in the direction of the axis BX is widely used. ing. Further, on the outer surface of the ceramic base 102, a pair of electrode pads 121 electrically connected to the heating resistor 141 is provided. A metal connection terminal 130 for externally applying a voltage to the heating resistor 141 is brazed to the electrode pad 121.

As shown in FIG. 2, in the ceramic substrate 102, alumina ceramic green sheets 140 and 146 are provided on the outer periphery of a round rod-shaped (cylindrical) alumina ceramic porcelain tube 101, and a green sheet is provided between the porcelain tube 101 and the green sheet 140. It is manufactured by being wound with 146 sandwiched therebetween and firing them. Here, since the perimeter of the green sheets 140 and 146 is shorter than the perimeter of the porcelain bushing 101, a cut 102h extending in the axis BX direction is formed between both ends of the green sheets 140 and 146, as shown in FIG. .
A heating resistor 141 is formed on the green sheet 140. The heating resistor 141 includes a heating portion 142 and a pair of lead portions 143 connected to both ends of the heating portion 142. A through hole 144 is provided on the rear end side of the green sheet 140, and the electrode pad 121 and the lead portion 143 are electrically connected via the conductive paste filled in the through hole 144.
On the other hand, the connection terminal 130 has a connection part 134, a joining end part 133 provided at one end of the connection part 134, and a caulking part 135 provided at the other end of the connection part 134. The joint end 133 is arranged substantially in the center of the electrode pad 121 and electrically connected by brazing. The two caulking portions 135 caulk and grip a core wire of a heater lead wire (not shown) to electrically connect the heating resistor 141 and the heater lead wire.

Conventionally, in manufacturing the ceramic heater 100, as shown in FIG. 5, the electrode pads 121 of the ceramic base 102 and the connection terminals 130 are aligned with each other, and then both are brazed.
First, the ceramic base 102 is placed between the two rotating rollers 501 and 502 arranged in the axial direction and rotating in opposite directions with the axial direction of the ceramic base 102 aligned with the axial directions of the rotating rollers 501 and 502. The ceramic base 102 rotates while contacting the rotating rollers 501 and 502. Then, when the image sensor above the rotary rollers 501 and 502 detects the break 102h, the rotation of the rotary rollers 501 and 502 is stopped. As a result, the electrode pads 121 of the ceramic base 102 are positioned at predetermined positions (in the example of FIG. 5, the electrode pads 121 are aligned horizontally).
Then, as shown in FIG. 6, while holding the ceramic substrate 102 by a predetermined jig 540 so as to maintain the orientation of each electrode pad 121, a pair of connections held by another jig 520 in a predetermined orientation. The ceramic substrate 102 is arranged between the terminals 130. At this time, the positions are determined so that each electrode pad 121 and each connection terminal 130 face each other, and the solidified brazing material 150x previously arranged on the connection terminal 130 side contacts the electrode pad 121.
Next, the ceramic substrate 102, the connection terminals 130, and the brazing material 150x are placed in a predetermined heating furnace in this arrangement, the brazing material 150x is melted, and the connection terminals 130 are brazed to the electrode pads 121.

Japanese Patent No. 5019545

However, in the case of manufacturing the conventional ceramic heater 100, since the cut 102h of the rotating ceramic base 102 is detected by the image sensor, there is a problem that it takes time to position the position or the position is mistakenly recognized. Further, since the ceramic base 102 rotates while making contact with the rotary rollers 501 and 502, scratches and dirt may be attached to the ceramic base 102.

Therefore, an object of the present invention is to provide a method for manufacturing a ceramic heater in which the electrode pad and the connection terminal are reliably positioned in a short time when brazing and the productivity is improved.

In order to solve the above-mentioned problems, a method for manufacturing a ceramic heater according to the present invention is characterized in that a heating resistor is embedded inside and the electrode pad in a cylindrical ceramic substrate having a metal electrode pad on the surface is connected to an external circuit and an electric circuit. A method of manufacturing a ceramic heater, in which connecting terminals that are electrically connected to each other are brazed together, wherein a center of gravity of the ceramic base is deviated from an axis, and the ceramic base is provided in a groove that can accommodate at least a part of the ceramic base. After installation, air is blown between the groove and the ceramic base to levitate the ceramic base from the groove, and the center of gravity of the ceramic base is stably positioned below the axis. The method includes a positioning step of positioning the electrode pad, and a joining step of brazing and joining the connection terminal to the electrode pad positioned in the positioning step.

According to this method for manufacturing a ceramic heater, air is blown between the groove and the ceramic base to float the ceramic base from the groove to position the electrode pad. It is possible to prevent scratches and stains from adhering to the substrate.
Further, since the positioning is autonomously performed by gravity by utilizing the shift between the center of gravity and the axis of the ceramic base, the positioning can be accurately performed without misrecognizing the positioning, and the positioning can be performed in a short time.

The radius of curvature of the groove may be larger than the radius of curvature of the ceramic substrate.
According to this method for manufacturing a ceramic heater, the contact area between the groove and the ceramic base is reduced, so that scratches and dirt can be further suppressed from adhering to the ceramic base, and the ceramic base can be easily floated from the groove.
The radius of curvature of the ceramic base is the radius of curvature of the outer surface of the ceramic base excluding the electrode pads.

After the positioning step, the flow rate of air blown between the groove and the ceramic base may be gradually reduced.
According to this method for manufacturing a ceramic heater, since the ceramic base is slowly landed in the groove, it is possible to further prevent the scratches and dirt from adhering to the ceramic base, and the ceramic base is abruptly landed and the positioning state is fluctuated ( It is possible to suppress the occurrence of misalignment).

According to the present invention, when the electrode pad and the connection terminal are brazed, the both can be aligned reliably and in a short time, and the productivity of the ceramic heater can be improved.

It is a perspective view which shows a ceramic heater. It is an exploded perspective view showing an internal configuration of a ceramic heater. It is a perspective view of a positioning jig which can be used for a manufacturing method of a ceramic heater concerning an embodiment of the present invention. It is process drawing which shows the positioning method of a ceramic heater. It is a figure which shows the positioning method of the conventional ceramic heater. It is a figure which shows the method of brazing the connection terminal to the electrode pad of the positioned ceramic heater.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 3 is a perspective view of a positioning jig 50 that can be used in the method of manufacturing the ceramic heater 100 according to the embodiment of the present invention, and FIG. 4 is a process diagram showing the method of positioning the ceramic heater 100. Note that FIG. 4 is a view seen from the side surface (direction A) of FIG. 3. Since the structure of the ceramic heater 100 itself is the same as the conventional one, the description of the ceramic heater 100 will be omitted with reference to FIGS. 1 and 2.
Of the both ends in the longitudinal direction of the ceramic heater 100, the side having the heat generating portion (the lower side in FIG. 1) is referred to as the “front end side”, and the opposite side is referred to as the “rear end side”.

In the present embodiment, the ceramic base 102 of the ceramic heater 100 has a round bar shape with a diameter of 3 mm and a total length of 50 mm. Further, for the connection terminal 130, various conductor materials such as an alloy using nickel, copper or iron, or an alloy thereof can be adopted. As the brazing material for brazing, for example, an Au-Cu alloy, an Ag-Cu alloy, or various conductor materials (for example, Cu (copper) or Ag (silver)) can be used. Examples of the electrode pad 121 include a composition containing at least one of tungsten and molybdenum as a main component.

As shown in FIG. 3, the positioning jig 50 is provided with a plurality of grooves 50r each having a substantially semicircular cross section on the surface thereof. The lower half of the ceramic base 102 can be accommodated. In addition, a plurality of blowout holes 50h are opened on the bottom surface of each groove 50r along the axial direction. Each of the blowout holes 50h is connected to the air piping system 60, and the air supplied by the compressor 65 is blown out from each of the blowout holes 50h via the air piping system 60.
The positioning jig 50 can be formed of various metals, resins, ceramics and the like.

The air piping system 60 is composed of a plurality (three in FIG. 3) of sub piping 62, 64, 66. On the other hand, outlet pipes 60L1, 60L2,... Are connected to the outlet holes 50h, and sub pipes 62, 64, 66 are connected to the outlet pipes 60L1, 60L2,. A flow rate adjusting valve V is arranged between each of the sub pipes 62, 64, 66 and the compressor 65, and the flow rate of the air flowing through each of the sub pipes 62, 64, 66 can be adjusted.
Further, in the present embodiment, the electrode pad 121 of the ceramic base 102 protrudes from the rear end side of each groove 50r. This prevents the electrode pads 121 protruding from the outer surface of the ceramic base 102 from coming into contact with the grooves 50r, and prevents the electrode pads 121 from being rubbed.

Then, as shown in FIG. 4, the electrode pad 121 of the ceramic heater 100 is positioned.
First, the ceramic base 102 is set in the groove 50r of the positioning jig 50 (FIG. 4A). At this time, the orientation of the ceramic base 102 (electrode pad 121) is random.
Next, when air is blown out from the blowout hole 50h, air is blown out between the groove 50r and the ceramic base 102, and the ceramic base 102 floats from the groove 50r. Here, the heating resistors 141 are embedded in the ceramic base 102 in a biased manner in one direction, and the heating resistors 141 made of metal have a larger specific gravity than the ceramic base 102. Therefore, the center of gravity G of the ceramic base 102 is deviated from the axis C.
Therefore, when air is blown out to levitate the ceramic base 102 from the groove 50r, the ceramic base 102 rotates around the axis until the center of gravity G is stably positioned below the axis C (FIG. 4(b): positioning). Process). As a result, the electrode pads 121 of the ceramic base 102 can be positioned at predetermined positions (in the example of FIG. 4B, the electrode pads 121 are aligned horizontally with each other).

Next, when the flow rate of air blown out from the blowout holes 50h is reduced (stopped), the ceramic base 102 lands on the groove 50r in a state where each electrode pad 121 is positioned (FIG. 4C).
Then, in the same manner as described with reference to FIG. 6, the connection terminal 130 is brazed to the electrode pad 121 (bonding step).
It should be noted that, after the ceramic base bodies 102 are installed in the respective grooves 50r of the positioning jig 50 and the plurality of ceramic base bodies 102 (the electrode pads 121 of the ceramic base bodies 102) are positioned at once, the plurality of ceramic base bodies 102 are put together by the jig 540. If each ceramic base 102 is held between the connection terminals 130 of each set that is held and similarly held in another jig 520, a plurality of ceramic bases 102 can be brazed at one time.

As described above, air is blown between the groove 50r and the ceramic base 102 to float the ceramic base 102 from the groove 50r and position the electrode pad 121, so that the ceramic base 102 does not come into contact with the positioning jig 50. Thus, it is possible to prevent the scratches and dirt from adhering to the ceramic base 102.
Further, since the positioning is autonomously performed by gravity by utilizing the deviation between the center of gravity G and the axis C of the ceramic base 102, the positioning can be accurately performed without misrecognizing the positioning, and the positioning can be performed in a short time. You can

Further, in the present embodiment, as shown in FIG. 4A, the radius of curvature R1 of the groove 50r is larger than the radius of curvature R2 of the ceramic base 102. By doing so, the contact area between the groove 50r and the ceramic base 102 becomes smaller, so that scratches and dirt can be further prevented from adhering to the ceramic base 102, and the ceramic base 102 can easily float from the groove 50r.
The radius of curvature R2 of the ceramic base 102 is the radius of curvature of the outer surface of the ceramic base 102 excluding the electrode pads 121.

After the positioning step, when the ceramic base 102 is landed in the groove 50r in FIG. 4C, the flow rate of air blown out from the groove 50r may be gradually reduced. By doing so, the ceramic base 102 slowly lands on the groove 50r, so that it is possible to further suppress the scratches and dirt from adhering to the ceramic base 102, and the ceramic base 102 abruptly lands and the positioning state fluctuates (position). Deviation can be suppressed.
As a method of gradually reducing the flow rate of the air blown out from the groove 50r, first of all the sub-pipes 62, 64, 66 of FIG. 3, one (for example, the sub-pipe 66) is stopped to reduce the flow rate. After that, the flow rates can be gradually reduced by stopping the auxiliary pipes 64 and 62 in order.
Further, the flow rate may be gradually reduced by a predetermined throttle valve.

It is needless to say that the present invention is not limited to the above-described embodiments and covers various modifications and equivalents included in the concept and scope of the present invention.
In the above-described embodiment, the center of gravity G of the ceramic base 102 is deviated from the axis C by the heating resistor 141. However, the present invention is not limited to this. Good.
The means for blowing air between the groove 50r and the ceramic base 102 to float the ceramic base 102 from the groove 50r is not limited to the positioning jig 50.

The ceramic heater 100 is arranged, for example, in the gas sensor, but may be arranged in another device. As the gas sensor, various gas sensors (oxygen sensor, NOx sensor, etc.) that detect the characteristic gas component or the concentration of the gas component can be exemplified.

50r Groove 100 Ceramic heater 102 Ceramic base 106 Outer electrode 108 Inner electrode 121 Electrode pad 130 Connection terminal 141 Heating resistor C Ceramic base axis G Ceramic center of gravity R1 Groove radius R2 Curvature radius R2 Ceramic base radius of curvature

Claims (3)

Manufacturing method of ceramic heater in which a heating resistor is embedded inside and a connecting terminal electrically connected to an external circuit is brazed to the electrode pad of a cylindrical ceramic substrate having a metal electrode pad on the surface. And
The center of gravity of the ceramic base is offset from the axis,
After installing the ceramic base in a groove capable of accommodating at least a part of the ceramic base, air is blown between the groove and the ceramic base to float the ceramic base from the groove, and the center of gravity is the axis. A positioning step of positioning the electrode pad of the ceramic base so as to be stably positioned below the core;
A bonding step of brazing and bonding the connection terminal to the electrode pad positioned in the positioning step,
And a method for manufacturing a ceramic heater. The method of manufacturing a ceramic heater according to claim 1, wherein a radius of curvature of the groove is larger than a radius of curvature of the ceramic base. 3. The method of manufacturing a ceramic heater according to claim 1, wherein after the positioning step, the flow rate of air blown between the groove and the ceramic base is gradually reduced to land the ceramic base on the groove.

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