KR20070031909A - Ceramic heater, and oxygen sensor and hair iron using the ceramic heater - Google Patents

Abstract

A ceramic base, a heat generating resistor embedded in the ceramic base, an external electrode having a thickness of 5 to 200 μm electrically connected to the heat generating resistor, formed on the surface of the ceramic base, and a lead member soldered to the external electrode; This provides a durable ceramic heater.

Description

CERAMIC HEATER, AND OXYGEN SENSOR AND HAIR IRON USING THE CERAMIC HEATER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ceramic heaters used for heating heaters, carburetor heaters, soldering iron heaters, and the like, for automotive air-fuel ratio detection sensors, and oxygen sensors and hair irons using the same.

Background Art Conventionally, ceramic heaters are widely used as heaters for heating of air-fuel ratio sensors used in automobiles, for example. The ceramic heater includes, for example, a heat generating resistor made of a high melting point metal such as W, Re, Mo, etc. in a ceramic base mainly composed of alumina, and a metal terminal (lead member) is bonded to the heat generating resistor through an external electrode. It is comprised by doing so (refer patent document 1, patent document 2).

The ceramic heater may, for example, prepare a ceramic core material and a ceramic sheet, print a paste of high melting point metal such as W, Re, and Mo on one surface of the ceramic sheet to form a heat generating resistor and an electrode lead-out unit, and then It is manufactured by winding a ceramic sheet around a ceramic core material so as to have an inner side and firing and integrating the whole (Patent Document 1).

More specifically, the ceramic sheet is provided with a heat generating resistor and an electrode lead portion connected thereto, and an external electrode is formed on the rear surface thereof. In addition, the electrode lead portion of the ceramic sheet is connected to the external electrode by a through-hole. Conductor paste is injected into the through hole as necessary.

In addition, the ceramic heater shown by FIG. 8A and b is the ceramic heater 51 shown by patent document 3. As shown in FIG. In the ceramic heater of FIG. 8, the extraction electrode 57 is connected to both ends of the heat generating resistor 53, and the extraction electrode 57 is exposed by the opening 58 formed in the ceramic base 52. 54 is soldered by brazing material such as solder.

The opening 58 exposing the extraction electrode 57 defines a region in which the extraction electrode 57 and the lead member 54 are soldered. Holes are formed in advance in the ceramic green sheet, which is the ceramic base 52, by a punching process. It is formed at the end of the ceramic base 52 by drilling.

In the ceramic heater of this patent document 3, the opening part 58 has the recessed part 56 of the magnitude | size corresponding to the diameter of the lead member 54 in the side wall, and the heat generating resistor 53 and the heat generating resistor 53 in the opening part 58 are formed. Inserting the lead member 54 into the recess 56 when soldering the lead member 54 makes it possible to accurately position the lead member 54 in the center portion of the heat generating resistor 53, and at the same time, As a result, the lead member 54 is attached to the heat generating resistor 53 very firmly by soldering.

(Patent Document 1) Japanese Unexamined Patent Publication No. 193-34313

(Patent Document 2) Japanese Unexamined Patent Publication No. 199-161955

(Patent Document 3) Japanese Unexamined Patent Publication No. 194-196253

However, the conventional ceramic heater has a problem that the joining portion deteriorates under the condition that the heat change is repeatedly applied to the electrode portion, and the durability decreases remarkably.

In recent years, the exhaust gas of automobiles has become stricter, and the oxygen sensor used for controlling the air-fuel ratio needs to be made faster, so that the starting characteristics of the ceramic heater used therein are also required. In such a situation, the above-mentioned problem becomes a more important subject.

That is, ceramic heaters used in devices requiring start-up operability have a strict use condition and tend to increase the temperature near the extraction electrode. As a result, stress is concentrated on the soldered portion due to the difference in thermal expansion between the brazing material and the ceramic base, so that higher durability is demanded. In particular, since a high reliability is required for the ceramic heater used for automobiles, very high durability is required.

For example, in a ceramic heater in which a heat generating region is wide and the ceramic heater is sandwiched by the holding member, such as a hair iron, the extraction electrode is rapidly heated at the same time as heating, so high durability is required for the soldered portion.

Accordingly, a first object of the present invention is to provide a ceramic heater having high durability.

Moreover, the 2nd object of this invention is to provide the oxygen sensor with high durability.

Further, a third object of the present invention is to provide a hair iron with high durability.

In order to achieve the above object, the first ceramic heater according to the present invention includes a ceramic substrate, a heat generating resistor embedded in the ceramic base, and a thickness of 5 to 200 μm that is electrically connected to the heat generating resistor and installed on the surface of the ceramic base. And an lead electrode soldered to the outer electrode.

In addition, the second ceramic heater according to the present invention is a ceramic base, a heat generating resistor embedded in the ceramic base, and electrically connected to the heat generating resistor and installed on the surface of the ceramic base to have a thickness of 5 to 50 μm, And an external electrode containing an additive composed of the same component as the main component of the ceramic base in a blending ratio of 1 to 10% by weight, and a lead member soldered to the external electrode.

The oxygen sensor according to the invention is characterized by having a first or second ceramic heater according to the invention.

A third ceramic heater according to the present invention comprises a ceramic base, a heat generating resistor embedded in the ceramic base, and an extraction electrode exposed from an opening formed in the ceramic base and electrically connected to the heat generating resistor, wherein the opening At least one part of a wall edge part in a wall, and / or at least one part of an outer periphery upper end part in the said opening part is at least 1 selected from the group which consists of C surface of 0.05 mm or more of chamfer dimensions, or R surface of 0.05 mm or more of radius.

In addition, in the present invention, the "C plane" refers to a chamfered state in which the edge portion formed by the intersection of the plane and the plane becomes an inclined plane, and the "R plane" refers to the chamfer so that each portion formed by the intersection of the plane and the plane becomes curved. Say the state.

In addition, a fourth ceramic heater according to the present invention includes a ceramic base, a heat generating resistor embedded in the ceramic base, an extraction electrode exposed from an opening formed in the ceramic base, and electrically connected to the heat generating resistor, and the extraction electrode. And a lead member brazed by a brazing material on the surface thereof, wherein the brazing material has a layer structure consisting of three or more metal layers.

In addition, the hair ironing according to the present invention is characterized in that any one of the first to fourth ceramic heaters according to the present invention is used as a heat generating means.

(Effects of the Invention)

In the first ceramic heater according to the present invention configured as described above, since the external electrode to which the lead member is soldered has a thickness of 5 to 200 μm, the external electrode portion and the periphery thereof are improved, and the lead member is joined. The strength can be improved.

In addition, in the second ceramic heater according to the present invention, the thickness of the external electrode to which the lead member is soldered is 5 to 50 µm, and the additive includes 1 to 10 weights of the external electrode having the same component as the main component of the ceramic base. Since it is contained in the compounding ratio of%, the durability of the external electrode portion and its surroundings can be further improved, and the bonding strength of the lead member can be improved.

Further, in the third ceramic heater according to the present invention, at least a part of the wall edge portion in the opening and / or at least a part of the outer periphery upper end portion in the opening has a C surface of 0.05 mm or more in the chamfer dimension or an R surface of 0.05 mm or more in the radius. At least one selected from the group consisting of can be used to alleviate stress concentration on the outer circumferential upper end due to the difference in thermal expansion between the brazing material and the ceramic base, thereby preventing the occurrence of cracks in the outer circumferential upper end.

Moreover, since the 4th ceramic heater which concerns on this invention has a layer structure which consists of three or more metal layers of the said brazing material, the said extraction electrode and a lead member can be firmly joined by the said brazing material.

Therefore, according to the 1st-4th ceramic heater which concerns on this invention, a highly durable ceramic heater can be provided.

Moreover, according to the oxygen sensor which concerns on this invention, since the 1st or 2nd ceramic heater which concerns on this invention is provided, the oxygen sensor with high durability can be provided.

Moreover, according to the hair ironing which concerns on this invention, since the ceramic heater in any one of the 1st-4th which concerns on this invention is used as a heat generating means, the hair ironing excellent in durability can be provided.

1A is a partially cutaway perspective view for explaining the configuration of a ceramic heater according to the first embodiment of the present invention.

1B is an exploded view of the ceramic substrate 2 in the ceramic heater of Embodiment 1. FIG.

FIG. 2 is an enlarged partial cross-sectional view of a cross section of a junction in the ceramic heater of Embodiment 1. FIG.

3A is a perspective view showing the structure of a ceramic heater of Embodiment 2 according to the present invention;

3B is a plan view of the ceramic sheet 22a for producing the ceramic heater of Embodiment 2. FIG.

3C is a plan view of the ceramic sheet 22b for producing the ceramic heater of Embodiment 2. FIG.

4 is an enlarged plan view of the extraction electrode in the ceramic heater according to the second embodiment;

Fig. 5A is a sectional view (1) of the extraction electrode of the ceramic heater of the second embodiment.

Fig. 5B is a sectional view 2 of the extraction electrode of the ceramic heater of the second embodiment.

Fig. 5C is a sectional view 3 of the extraction electrode of the ceramic heater of the second embodiment.

6 is an enlarged cross-sectional view of a soldering portion of the ceramic heater according to the third embodiment of the present invention.

7 is a perspective view showing an example of a hair iron using the ceramic heater of the present invention.

8A is a plan view of a conventional ceramic heater.

8B is an enlarged perspective view of a extraction electrode of a conventional ceramic heater.

(Explanation of the sign)

1, 21 ： ceramic heater

2, 22 ceramic ceramic

3, 23: Heat generation resistor

3a ： electrode lead-out

4: external electrode

5: plating layer

6, 25 ： Soldering material

7, 24 ： Lead member

8, 22a, 22b: Ceramic sheet

9: Through hole

10 ： ceramic heartwood

20: Paste

21c: Surface C

22s: Wall surface

26: Concave department

26e: Wall surface edge in recess part

27: extraction electrode

28: Opening department

28e: Wall edge at the opening

29: Plating layer

30e ： Upper part of outer circumference

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1

FIG. 1A is a partially broken perspective view showing the structure of a ceramic heater according to the first embodiment of the present invention, and FIG. 1B is a developed view of a portion of the ceramic base 2.

In the ceramic heater 1 of the first embodiment, as shown in FIG. 1A, a heat generating resistor 3 is incorporated in the ceramic substrate 2. In addition, the ceramic heater 1 of the first embodiment includes an external electrode 4 that supplies electricity to the heat generating resistor 3 on the surface of the ceramic base 2, and the plating layer 5 is formed on the external electrode 4. The lead member 7, which is a metal terminal, is joined via the brazing material 6. In particular, the ceramic heater 1 of the first embodiment is characterized in that the thickness of the external electrode 4 is 5 to 200 m.

The ceramic heater 1 of this Embodiment 1 is produced as follows.

First, the ceramic core material 10 and the ceramic sheet 8 are prepared, and a paste of high melting point metal such as W, Re, Mo, etc. is printed on one surface of the ceramic sheet 8 to generate the heat generating resistor 3 and the electrode lead-out portion ( To form 3a).

And the ceramic sheet 8 is wound around the ceramic core material 10 so that the surface in which the heat generating resistor 3 and the electrode lead-out part 3a were formed may be wound, and the whole may be baked and integrated.

In this way, the ceramic sheet 8 is manufactured by bringing the ceramic sheet 8 into close contact with the ceramic core material 10 so that the heat generating resistor 3 is inward and then baked.

As a ceramic material constituting the ceramic base 2, various ceramic mixes such as alumina ceramics, silicon nitride ceramics, aluminum nitride ceramics and silicon carbide ceramics can be used, but in particular, ceramic materials whose main component is alumina or silicon nitride It is preferable to employ, and thereby, a ceramic heater excellent in rapid temperature rise and durability can be obtained. For example, in the case of alumina ceramics, 88 to 95% by weight of Al ₂ O ₃ , ₂ to 7% by weight of SiO ₂ , 0.5 to 3% by weight of CaO, 0.5 to 3% by weight of MgO, and ZrO ₂ to 1 The composition which consists of-3 weight% is preferable. In addition to the above components, a small amount of impurities may be contained. If the Al ₂ O ₃ content is less than 88% by weight, the glass quality increases, so there is a fear that migration during energization will increase. On the other hand, when the Al ₂ O ₃ content exceeds 95% by weight, the amount of glass diffused into the metal layer of the heat generating resistor 3 embedded in the ceramic base 2 may decrease, which may deteriorate the durability of the ceramic heater 1. In the case of silicon nitride ceramics, 3 to 12% by weight of rare earth element oxide, 0.5 to 3% by weight of Al ₂ O ₃ as the sintering aid with respect to silicon nitride of the main component, and 1.5 to SiO ₂ contained in the sintered body It is preferable to mix SiO ₂ so that it may become 5 weight%. The amount of SiO ₂ shown here is the sum total of SiO ₂ as an impurity contained in SiO ₂ generated from impurity oxygen contained in the silicon nitride raw material and other additives, and SiO ₂ intentionally added. In addition, by dispersing MoSi ₂ or WSi ₂ in silicon nitride as the base material, it is possible to improve the durability of the heat generating resistor 3 by making the thermal expansion rate of the base material approach the thermal expansion rate of the heat generating resistor 3.

In addition, in the case of using the aluminum nitride it is preferably used that the rare-earth element oxide or CaO, such as Y ₂ O ₃ 2-8% by weight was added as a sintering aid for aluminum nitride.

In addition, in Embodiment 1, the ceramic base body 2 which consists of the ceramic core material 10 and the ceramic sheet | seat 8 is a cylinder or cylinder shape whose outer diameter is 2-20 mm, and the length is about 40-200 mm, for example. In particular, when used for heating the air-fuel ratio sensor of an automobile, it is preferable that the outer diameter is 2-4 mm and the length is 40-65 mm in the cylinder or cylinder shape. In addition, although the cylindrical shape was made in Embodiment 1, this invention is not limited to this, A flat plate shape may be sufficient as it.

The electrode lead-out portion 3a formed to be connected to the heat generating resistor 3 and the heat generating resistor 3 is made of a material mainly composed of a high melting point metal such as W, Mo, and Re, and the electrode lead-out portion 3a is shown in FIG. It is connected to the external electrode 4 via the through hole 9 shown.

As shown in Fig. 2, the external electrode 4 is formed around the through hole 9 on the surface of the ceramic substrate 2, and the material is metallized mainly of high melting point metals such as W, Mo, and Re. Consists of layers. In particular, the main component is preferably W or W compound, and since these are high melting point metals having excellent oxidation resistance, the sintering can be performed while maintaining the shape of the external electrode. And it is important that the thickness D of the external electrode 4 is 5-200 micrometers. The thickness D is required to be this thickness as the average thickness of the entire external electrode 4. When the thickness of the external electrode 4 is set in such a range, the stress caused by the difference in thermal expansion between the ceramic base 2 and the metal brazing material 6 can be alleviated, and the thermal history is repeatedly applied to the junction terminal portion. Even if losing, the strength and durability of the joint can be sufficiently secured. If the thickness is less than 5 µm, there is a problem in that the bonding strength of the lead member 7 after the cycle test is significantly degraded due to the difference in thermal expansion due to repeated application of thermal load. If the thickness exceeds 200 µm, the bonding force in the thickness direction of the external electrode is lowered, and there is a problem that the bonding strength of the lead member 7 due to peeling from the inside of the external electrode occurs due to the heat load.

In particular, by making this thickness D into 5-50 micrometers, durability can be improved more effectively. The external electrode 4 may be printed or transferred to the other main surface of the ceramic sheet 8 in contact with the rear surface of the electrode lead-out portion 3a in the same manner as forming the heating resistor 3 and the electrode lead-out portion 3a. It can form using.

In addition, the external electrode 4 can be made thicker by increasing the mesh aperture ratio of the plate making used in printing. However, if it is too high, a problem arises in the smoothness of each surface of the formed external electrode 4, and this time, the examination was also including other parameters. As a result, with the examination of the mesh aperture ratio of the said plate making, it became possible to form thicker by making the moving speed of the coating squeegee used for printing similarly high. In addition, when printing, it is possible to form thicker by increasing the pressure to press the squeegee from above. Moreover, the shape of the contact part with the plate making of the said squeegee is also important, and it becomes possible to form thickly by making the shape of the contact part more round. In addition, by forming the squeegee in the direction of movement of the squeegee at an angle of 90 degrees or less, it is easy to form a thick one. In addition, it is possible to form thicker by increasing the viscosity with respect to the pasty external electrode viscosity before printing, but it is necessary to fully consider the omission from plate making. It is also very effective to thicken the plate making itself.

In this manner, in forming the external electrode 4 thickly, the aperture ratio, the squeegee speed and pressure, the squeegee shape and the slope, the viscosity of the external electrode in the form of paste, the omission of the plate making, the thickness and the overall balance of the plate making itself are considered. I found a condition of superiority that can form thickly.

Further, by making the width H1 of the external electrode 4 formed on the surface of the ceramic base 2 larger than the width H of the lead member 7 to be described later, the solder material 6 has an end portion of the external electrode than the lead member 7. By forming the meniscus of the brazing material so that the flows smoothly, the strength can be stabilized. In this case, the width H1 of the external electrode 4 does not become smaller than the width H of the lead member 7, but the strength can be maintained. More preferably, the bonding strength can be increased by making H1 1.1 times or more. .

In addition, since the additive including the main component of the ceramic base 2 is contained in the external electrode 4 (not shown), the additive diffuses into the ceramic base 2, and the ceramic base 2 itself is the external electrode ( By mutually diffusing to 4), the adhesion strength of the external electrode 4 to the ceramic substrate 2 increases. Here, the blending ratio in the external electrode 4 of the additive consisting of the main component of the ceramic base 2 is preferably 1 to 30% by weight, more preferably 1 to 10% by weight, whereby Further improvement in the adhesion strength of the external electrode due to diffusion is achieved.

In particular, since the thickness D of the external electrode 4 is 5-50 micrometers, and the compounding ratio in the external electrode of the additive which consists of the main component of the ceramic base 2 is 1-10 weight%, the strength and durability are the best. Excellent ceramic heaters can be obtained.

Furthermore, the plating layer 5 may be formed on the surface of the external electrode 4 as shown in FIG. By forming the plating layer 5 on the external electrode 4, the flow of the brazing material 6 is improved and the soldering strength is improved. As a material of the plating layer 5, it consists of Ni, Cr, a composite material containing these as a main component, etc., and is formed in the thickness of 1-5 micrometers.

On the external electrode 4, a lead member 7 made of Ni-based, Fe-Ni-based alloy or the like having good heat resistance as a metal terminal is soldered using the brazing material 6. As the material, the brazing material 6 contains Ag-Cu, Au-Cu, Ag, Cu, Au, etc. as a main component, and, if necessary, contains a resin such as a binder or metals such as Ti, Mo, and V as active metals. It is formed using a brazing material and is formed by curing in a reducing atmosphere containing water vapor.

Next, the manufacturing method of the ceramic heater of Embodiment 1 is demonstrated.

First, as the main component and alumina is prepared a ceramic sheet 8 forming a ceramic slurry containing 4 to 12% by weight of _{SiO 2, CaO, MgO, ZrO} 2 in a total amount as a sintering aid.

The heat generating resistor 3 and the electrode lead-out portion 3a are formed on one main surface of the ceramic sheet 8 by a method such as printing or transfer, and the ceramic sheet 8 is in contact with the back surface of the electrode lead-out portion 3a. The external electrode 4 is formed on the other main surface in the same manner by printing or transferring.

Next, a through hole 9 is formed between the electrode lead portion 3a and the external electrode 4, and the through hole 9 is filled with a conductive material composed mainly of at least one of W, Mo, and Re. Or by coating the inner surface of the through hole 9 so that the electrode lead-out portion 3a and the external electrode 4 can be electrically connected.

Thereafter, a coat layer having a composition substantially equivalent to that of the ceramic sheet 8 is formed on the heat generating resistor 3 and the electrode lead-out portion 3a, and then the ceramic sheet 8 is circumferentially adhered to the ceramic core material 10. Thereby forming a cylindrical shaped body. The product body thus obtained is calcined in a reducing atmosphere at 1500 to 1650 ° C. to obtain a ceramic base 2.

Then, the plating layer 5 which consists of metals, such as Ni and Cr, is formed in the surface of the external electrode 4 by the electric field plating method or the electroless plating method.

Next, the external electrode 4 and the lead member 7 are bonded in a reducing atmosphere containing water vapor using a brazing material mainly composed of Au-Cu.

Embodiment 2

Next, the ceramic heater of Embodiment 2 which concerns on this invention is demonstrated, referring FIGS. 3A-C.

The ceramic heater 21 of the second embodiment is a flat ceramic heater having a ceramic body 22 having a heat generating resistor 23 therein, and is exposed by the opening 28 of the ceramic body 22. The lead member 24 is soldered and fixed to the taken out electrode 27.

In the ceramic heater 21 of the second embodiment, as shown in FIG. 3B, the heat generating resistor 23 and the extraction electrode 27 connected thereto are formed on the surface of the ceramic sheet 22a, and shown in FIG. 3C. As described above, it can be produced by stacking the openings 28 and the other ceramic sheets 22b formed with the recesses 26 in close contact with each other and firing in a reducing atmosphere at 1500 to 1650 ° C.

In the ceramic heater of Embodiment 2, at least a part of the corner portion of the wall surface in the opening portion and / or at least a portion of the outer peripheral upper end portion in the opening portion is selected from the group consisting of a C surface of 0.05 mm or more in chamfer dimension or an R surface of 0.05 mm or more in radius. It is characterized by at least one.

In the case of the ceramic heater shown in FIG. 4, the R surface of 0.05 mm or more in radius is formed in the wall surface edge part 28e in the opening part 28. As shown in FIG. This improves the durability of the electrode portion. Moreover, the R surface of 0.05 mm or more in radius is formed also in the wall surface edge part 26e in the recessed part 26. As shown in FIG.

If the C surface or R surface processing is less than 0.05 mm, it is difficult to effectively improve the durability of the electrode portion due to the stress caused by the difference in thermal expansion between the brazing material and the magnetic being concentrated on the edge portion 28e. Moreover, in order to improve the durability of an electrode part more preferably, C surface or R surface processing is 0.1 mm or more, More preferably, it is 0.2 mm or more.

In addition, the C surface of the outer peripheral upper end portion 30e (see FIG. 5B), which is a boundary between the wall surface 22s of the opening portion 28 (or the recess 26) and the upper surface of the ceramic base 2 (see FIG. 5B), has a chamfer of 0.05 mm or more. It is preferable to form (21c) (see FIG. 5C). The outer circumferential upper end portion 30e may be provided with an R surface of 0.05 mm or more in radius. In addition, although the C surface or R surface processing of the outer periphery upper end part 30e is performed over the outer periphery of the opening part 28 and the recessed part 26, it is preferable that a brazing | sold material and a magnetic material with respect to the outer periphery upper end part 30e. C surface or R surface processing may be performed to a part where stress due to the difference in thermal expansion is easily concentrated.

In addition, as shown in FIG. 5C, when the C surface 21c (or R surface) is formed in the outer periphery upper end part 30e of the upper end of the wall surface 22s of the opening part 28, when the lead member 24 is installed, (24) can be prevented from being damaged. Such damage is a cause of corrosion generated when the ceramic heater 1 is used, and thus such a C surface 21c (or R surface) is also useful for improving durability.

This C surface or R surface processing makes it possible to suppress the generation of processing waste when processing the openings in the ceramic sheet 22b. Therefore, adhesion failure between the ceramic sheets 22a and 22b in which the processing waste is in close contact is eliminated. The problem which generate | occur | produces and reduces durability of the heat generating resistor 23 can be prevented beforehand.

4, it is preferable that 50% or more of the outer periphery (outer side) of the extraction electrode 27 exposed by the opening part 28 is embedded in the ceramic base 22. As shown in FIG. When the lead member 24 is soldered to the extraction electrode 27, the thermal expansion rate with respect to the ceramic base 22 is different. Therefore, when the brazing material flows to the outer circumference of the extraction electrode 27, the thermal expansion difference is caused around the outer circumference. The stress is concentrated. For this reason, if more than 50% of the outer circumference of the extraction electrode 27 is exposed without being embedded in the ceramic, cracks are likely to occur in the outer circumferential portion exposed by the heat cycle during use.

For this reason, by burying 50% or more of the outer circumference of the extraction electrode 27 in the ceramic base 22, it is possible to prevent the occurrence of cracks in the outer circumference portion, thereby preventing the durability. More preferably, when more than 75% of the outer circumference of the extraction electrode 27 is embedded in the ceramic base 22, cracks can be more effectively prevented. In addition, the angle θ formed between the wall surface 22s and the extraction electrode 27 in the opening 28 is preferably set to 60 to 110 degrees. Here, the angle θ formed between the wall surface 22s and the extraction electrode 27 is an angle formed between the surface of the portion embedded in the ceramic body 22 of the extraction electrode 27 and the wall surface 22s, as shown in FIG. 5A.

When the angle θ exceeds 110 degrees, the stress at the time of expansion and contraction of the brazing material 25 formed up to the wall surface 22s acts on the end of the brazing material 25, and the ceramic body 22 at the end of the brazing material 25 is applied. ) Is likely to cause cracks.

When the angle θ is less than 60 degrees, pressure is applied to the interface between the extraction electrode 27 and the ceramic sheet 22a in the opening 28 when the ceramic sheet 22b is brought into close contact with the ceramic sheet 22a. It is not preferable because it becomes difficult and adhesion worsens, and a space | gap arises and the effect which prevents peeling of the extraction electrode 27 becomes small.

Moreover, it is more preferable to set angle (theta) to 60-90 degree.

Further, the angle θ formed between the wall surface 22s and the extraction electrode 27 is 110 degrees or less in the vicinity of the interface between the extraction electrode 27 and the wall surface 22s (for example, within a range of 0.2 mm from the boundary). Preferably, when it is set at 90 degrees or less, the concentration of the stress at the time of expansion and contraction of the brazing material 25 at the end of the brazing material 25 can be prevented, and the crack of the ceramic base 22 can be prevented. .

In addition, as shown in FIG. 5B, the paste 20 having the same quality as that of the ceramic base 22 is disposed and baked when the opening 28 is in close contact with the extraction electrode 27. It is possible to prevent the solder 25 from flowing to the wall surface 22s.

Thus, the solder material 25 does not flow to the wall surface 22s of the opening 28 so that even if the angle θ becomes 110 degrees or more, the stress such as pushing up the wall surface 22s by the thermal expansion of the solder material 25 is achieved. As a result, cracks can be prevented from occurring at the end of the extraction electrode 27 in the opening 28.

In addition, when using a metal plate superimposed on the ceramic heater 21, it can prevent that a crack generate | occur | produces in the vicinity of C surface 21c (or R surface).

In addition, the thickness of the extraction electrode 27 is preferably set to 10 µm or more, and when the thickness is less than 10 µm, the adhesion strength with the ceramic substrate 22 of the extraction electrode 27 is low, which leads to thermal cycle in use. Since the durability of the tensile strength of the member 24 falls, it is not preferable.

More preferably, it is preferable to set it as 15 micrometers or more, ideally 20 micrometers or more.

The reason why the thickness of the extraction electrode 27 affects the tensile strength of the lead member 24 is as follows. That is, the extraction electrode 27 diffuses the glass component of the grain boundary from the ceramic base 22 into the gap while the high melting point metal made of W, Mo, Re, and the like is sintered in the porous material, and the strength is obtained by the anchor effect. Increases. Therefore, as the thickness of the extraction electrode 27 increases, the tensile strength of the lead member 24 increases.

As the material used for the heat generating resistor 23, it is also possible to use W, Mo, Re alone or alloys thereof, or metal silicides such as TiN and WC, metal carbides, and the like.

When such high melting point materials are used as the material of the heat generating resistor 23, the sintering of the metal does not proceed during use, and thus the durability is improved.

As shown in FIG. 5A, when the peripheral portion of the extraction electrode 27 is sandwiched between the ceramic substrates 22, the bonding strength of the extraction electrode 27 can be improved.

As shown in FIG. 5B, by forming the primary plating layer 29 on the surface of the extraction electrode 27 as necessary, it is possible to improve the flowability of the brazing material 25 when soldering the lead member 24. It becomes possible. At this time, if the soldering temperature of the soldering material 25 which fixes the lead member 24 is set to 1000 degrees C or less, the residual stress after soldering can be reduced.

In the case where the ceramic heater 21 is used in a high humidity atmosphere, it is preferable to use the Au-based or Cu-based brazing material 25 because migration hardly occurs. As the brazing material 25, Au, Cu, Au-Cu, Au-Ni, Ag, Ag-Cu-based materials are used. As the Au-Cu solder, the Au content is 25 to 95% by weight, and as the Au-Ni solder, a substance having a component amount of 50 to 95% by weight of Au is used. When Ag content is 60 to 90% by weight, more preferably 70 to 75% by weight, the Ag-Cu solder has a composition of the process point, which can prevent the rise of the temperature during soldering and the formation of an alloy having a heterogeneous composition at the time of temperature drop. Therefore, it is good to be able to reduce the residual stress after soldering.

In the case of using in a high humidity atmosphere, it is preferable to use Au-based or Cu-based solder material 25 because migration hardly occurs.

Moreover, it is preferable to form the secondary plating layer which consists of Ni normally on the surface of the brazing material 25, in order to improve the high temperature durability and protect the brazing material 25 from corrosion.

In addition, in order to improve durability, it is effective to set the particle diameter of the crystal constituting the secondary plating layer to 5 µm or less, and if the particle diameter is larger than 5 µm, the strength of the secondary plating layer is weak and brittle, so that there is a risk of cracking under a high temperature standing environment. have.

In addition, although the reason is not clear, it is thought that the small particle diameter of the crystal which forms a secondary plating layer can prevent micro defects because a plating process is smooth (the density of a plating layer is high), and this secondary plating layer is a boron system. It is preferable to use electroless Ni plating.

In addition, the type of electroless plating may be coated with a phosphorus-based electroless plating layer in addition to the boron-based electroless plating. However, when there is a possibility that it may be used in a high temperature environment, it is common to carry out boron-based electroless Ni plating. The particle diameter of the secondary plating layer can be controlled by changing the heat treatment temperature after secondary plating.

As the material of the lead member 24, it is preferable to use Ni-based or Fe-Ni-based alloy having good heat resistance, which is caused by the heat transfer from the heat generating resistor 23 to increase the temperature of the lead member 24 during use. This is because there is a possibility of deterioration.

Among them, when Ni or Fe-Ni alloy is used as the material of the lead member 24, the average crystal grain size is preferably 400 µm or less, and when the average grain diameter exceeds 400 µm, vibration and thermal cycles during use are caused. This is not preferable because the lead member 24 near the solder portion fatigues and cracks.

Also for other materials, if the particle diameter of the lead member 24 becomes larger than the thickness of the lead member 24, for example, stress concentrates at grain boundaries near the boundary between the solder member 25 and the lead member 24, resulting in cracks. It is undesirable because it occurs.

In addition, in order to reduce the imbalance between samples, the heat treatment at the time of soldering requires heat treatment at a high temperature with sufficient margin above the melting point of the solder material 25, but the average crystal grain size of the lead member 24 is reduced to 400 µm or less. In order to do this, the temperature during soldering should be kept as low as possible to shorten the treatment time.

In addition, in the case of using alumina as ceramic material for the heater 21, the Al ₂ O ₃ 88~95% by weight, SiO ₂ 2~7% by weight, CaO 0.5~3% by weight, MgO 0.5~3% by weight, ZrO ₂ 1 It is preferable to use alumina which consists of-3 weight%. Here, although the example of alumina was shown as ceramics, it is not limited to the alumina ceramics shown by this invention, Not only the ceramic nitride 1, such as silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, This is a phenomenon suitable for all of Au-based soldering.

Embodiment 3

Next, the ceramic heater of Embodiment 3 which concerns on this invention is demonstrated, referring drawings.

The ceramic heater of the third embodiment is the same as that of the second embodiment except that the brazing material 35 for soldering the lead member 24 to the extraction electrode 27 is different.

The feature of the third embodiment lies in the structure of the soldering part 35 in which the extraction electrode 27 and the lead member 24 are soldered. In the ceramic heater 1 of Embodiment 3 of the present invention, Ag-Cu solder used as the soldering material is most commonly used as a material for holding and holding the lead member 24.

The soldering part 35 between the extraction electrode 27 and the lead member 24 has the first layer 35a, the second layer 35b, and the third in order from the extraction electrode 27 side as shown in FIG. The layer which consists of three layers of the layer 35c is formed, and the process part 35d is mounted on it.

In order to form such a structure, a plating layer is applied to the surface of the extraction electrode 27, and the lead member 24 is soldered using a brazing material such as Ag-Cu solder (BAg-8). At this time, by adjusting the melting temperature (solder temperature) and melting time (storage holding time) of the soldering material to predetermined conditions in accordance with the material constituting the brazing material and the plating layer, the conductive material in the extraction electrode 27 and the inside of the brazing material are adjusted. The component is diffused into the plating layer. As a result, three layers of the first layer 35a, the second layer 35b, and the third layer 35c are formed between the extraction electrode 27 and the process portion 35d.

As the material of the lead member 24, an Ni or Fe-Ni-based alloy such as Fe-Ni-Co alloy or the like is preferably used.

As the conductive material of the extraction electrode 27 (denoted as Me), a single melting point metal or an alloy of high melting point metals such as W, Mo, and Re is used as appropriate.

The first layer 35a closest to the extraction electrode 27 is a layer formed by diffusing a conductive material Me from the extraction electrode 27 to a plating layer made of Ni formed on the extraction electrode 27 and diffusing Cu from the brazing material. And Ni (Me) Cu layer containing Ni as a main component. In the third embodiment, the bonding strength between the extraction electrode 27 and the brazing material is improved by the Ni (Me) Cu layer. The first layer 35a is preferably a NiWCu layer containing Ni as a main component, and the NiWCu layer can further strengthen the bonding strength between the extraction electrode 27 and the brazing material. The first layer 35a made of NiWCu forms the extraction electrode 27 by W, diffuses W from the extraction electrode 27 in the Ni layer on the extraction electrode 27, and diffuses Cu from the brazing material. It can form by making it.

The second layer 35b formed on the first layer 35a is a NiCu layer containing Ni as a main component. Ni is most contained in this 2nd layer 35b. The second layer 35b of Ni-rich is made of Ni in the plating layer formed on the surface of the extraction electrode 27 and Cu of the brazing material 35 before soldering. This second layer 35b acts as a protective layer of the first layer 35a in which W is dissolved.

The third layer 35c formed on the second layer 35b is a CuNi layer containing Cu as a main component. Cu is most contained in this 3rd layer 35c. In addition, Ag may be contained in this 3rd layer 35c. This third layer 35c acts as a stress relaxation layer that relieves the stress caused by the difference in thermal expansion between the original process phase 35d of the Ag—Cu solder and the extraction electrode 27.

Since the composition of the 2nd layer 35b and the 3rd layer 35c differs as mentioned above, it can distinguish from a hue difference, for example by SEM (scanning electron microscope) photograph.

In the ceramic heater of the third embodiment configured as described above, the first layer 35a, the second layer 35b, and the third layer 35c are formed between the process portion 35d and the extraction electrode 27 as described above. It is possible to improve the tensile strength of the lead member 24 and to improve the durability.

The first layer 35a, the second layer 35b, and the third layer 35c preferably each have an average thickness of 2 to 30 µm, more preferably 2 to 20 µm, and even more preferably. It is set to 2-12 micrometers.

If the thickness is less than 2 mu m, the tensile strength of the lead member 24 cannot be effectively improved, and if the thickness exceeds 30 mu m, there is a tendency to become soft because the difference in properties between the layers is particularly effective. As this length becomes longer, tensile strength falls, which is not preferable.

The thickness of the second layer 35b is influenced by the thickness of the Ni plating layer formed on the extraction electrode 27, and the thickness of the Ni plating layer is preferably 2 to 30 mu m.

The third layer 35c is formed as a reaction generating intermediate layer between the process layer of the Ag—Cu brazing material and the Ni plating layer.

The thickness of the 1st layer 35a, the 2nd layer 35b, and the 3rd layer 35c is influenced by the melting temperature (solder temperature) and melting time (storage holding time) of a brazing material. The soldering temperature and storage time of a brazing material are appropriately determined according to the material which comprises a brazing material, and the material which comprises a plating layer, and are not specifically limited to this. For example, when the soldering temperature is set to about 800 to 900 ° C. using BAg-8 (JIS standard) as the Ag-Cu solder, the storage holding time is about 0.5 to 5 hours, preferably about 1 to 5 hours. More preferably, it is good to adjust to about 1-2 hours.

In the ceramic heaters of Embodiments 2 and 3 described above, oxide ceramics such as alumina, mullite, and forsterite, and non-oxide ceramics such as silicon nitride and aluminum nitride are used as materials of the ceramic substrate 22. Although it is possible to use etc., it is preferable to use oxide ceramics.

7 is a perspective view which shows an example of the hair ironing using the ceramic heater of embodiment 2 or 3 which concerns on this invention.

This hair ironing inserts hair between the arms 42 of the tip, and presses the handle 41 to pressurize the hair while heating the hair. The ceramic heater 46 is inserted in the arm 42, and the metal plate 43, such as stainless steel, is provided in the part which directly contacts hair.

In addition, the outer side of the arm 42 has a structure in which a heat-resistant plastic cover is attached to prevent burns.

As mentioned above, although the ceramic heater which concerns on embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various change is possible as long as it does not deviate from the summary.

(Example)

Example 1.

In Example 1, in order to confirm the validity of the invention according to Embodiment 1, a test product was produced and tested as follows.

First, FIG mainly composed of Al ₂ O ₃ as the ceramic body (2) to obtain the ceramic heater sample shown in Fig. 1, and SiO _2, CaO, MgO, ceramic sheet (8 was adjusted such that the total of less than 10% by weight of ZrO ₂ ), A heat generating resistor 3 made of W-Re and an electrode lead portion 3a made of W were printed. In addition, the external electrode 4 was printed on the back surface of the ceramic sheet 8.

Then, a through hole was formed at the end of the electrode lead-out portion 3a made of W, and a paste was injected therein to obtain conduction between the external electrode 4 and the electrode lead-out portion 3a. The position of the through hole was formed so as to enter the inside of the soldered portion when soldering was performed.

Next, after forming the coating layer which consists of the substantially same component as the ceramic sheet 8 on the surface of the heat generating resistor 3, and fully dried, the adhesive liquid which disperse | distributed the ceramics of substantially the same composition as the said ceramic sheet 8 again is carried out, The ceramic sheet 8 thus prepared was brought into close contact with the circumference of the ceramic core 10 and fired at 1500 to 1600 ° C.

Further, a plating layer 5 made of Ni is formed on the surface of the external electrode 4, heat treated at 700 to 800 ° C. in a reducing atmosphere, and then a diameter made of Ni using a brazing material 6 made of Au-Cu. A 0.8 mm lead member 7 was soldered at 830 ° C. in a reducing atmosphere, and a plating layer made of Ni was formed on the surface of the lead member 7 at an end thereof and then heat treated at 700 ° C.

The ceramic heater obtained as described above was subjected to various thicknesses and additive blending ratios of the external electrodes 4 to prepare samples.

The resistance value of the ceramic heater sample thus obtained was measured using a digital multimeter, and the stability of the flicker of the digital value was confirmed.

Then, the ceramic heater was leveled, fixed with a holding mechanism, the lead member was pulled in the vertical direction with respect to the solder surface of the lead member, and the initial bonding strength of the lead member 7 was measured by a digital force gauge. .

Moreover, the high temperature durability of the electrode part of the sample of the obtained ceramic heater was evaluated. The ceramic heater was placed in a high temperature durability furnace and left at high temperature for 400 minutes at 400 ° C., followed by cycle evaluation of less than 100 ° C. in 3 minutes, and the tensile strength of the lead member after 3000 cycles was examined. The results are shown in Table 1.

Table 1

As shown in Table 1, the samples (Nos. 3 to 28) having an external electrode thickness of 5 to 200 µm, which are ceramic heaters according to the present invention, had 70 N or more as the initial bonding strength, and sufficient strength could be ensured. Moreover, also about the joint strength of the lead member 7 after cycling, the strength which does not produce a practical problem more than 50N was securable.

Among them, samples (Nos. 4 to 8, 10, 12, 14, 16 to 20, 22, and 24 to 28) in which additives were added to the external electrode had an initial bond strength of 100 N or more, and the bond strength after the cycle was performed. Higher than 70N was able to secure more sufficient strength.

In particular, the initial bonding strength and the cycle performance are performed for the samples (Nos. 4 to 7, 7, 10, 12, 14, 16 to 19, 22, and 24 to 27) in which the additive blending ratio is 1% by weight to 30% by weight. Not only the subsequent bonding strength is sufficiently secured, but also the resistance is stable, there is no flicker, and the stability of product characteristics is also excellent.

Then, the lead after the cycle was performed for samples (Nos. 4 to 6, 10, 12, 14, 16 to 18) having an external electrode thickness of 5 to 50 µm and an additive blending ratio of 1 to 10 weight percent. The joining strength of the member also has a strength of 100 N or more which is almost unchanged from the initial joining strength, and can be said to be particularly excellent.

Next, the width H1 of the external electrode 4 of the obtained ceramic heater was divided for every thickness of the external electrode, and the sample was produced.

Then, the bonding strength of the lead member 7 after 3000 cycles of initial bonding strength and endurance test of the ceramic heater sample was examined as described above. These results are shown in Table 2.

Table 2

As shown in Table 2, for samples (Nos. 32 to 35, 37 to 40, 42 to 45) in which the width H1 of the external electrode was larger than the width H of the lead member, the initial bonding strength was 100 N or more, Also about the joining strength of the lead member 7, it has the strength of 70N or more, and sufficient strength is ensured.

In particular, for samples (Nos. 33 to 35, 38 to 40, 43 to 45) in which the width H1 of the external electrode is 1.1 times larger than the width H of the lead member, the bonding strength of the lead member 7 after the cycle is performed. It is said to be particularly excellent because it has a strength of 100 N or more which is almost unchanged from the initial bond strength.

Example 2

Examples 2 to 5 described next are examples relating to Embodiment 2 of the present invention.

A ceramic sheet 22a having Al ₂ O ₃ as a main component and having been adjusted so that SiO ₂ , CaO, MgO, and ZrO ₂ to be within 10% by weight in total is prepared, and is shown in FIG. 3B on the surface of the ceramic sheet 22a. As described above, a paste made of W was printed to form the heat generating resistor 23 and the extraction electrode 27.

Then, the opening part 28 and the recessed part 26 which changed various shapes are formed in the other ceramic sheet 22b, the ceramic sheet 22b is piled up on the said ceramic sheet 22a, and it adheres closely, and it is 1600 degreeC It baked in the reducing atmosphere of 20, and prepared 20 ceramic heaters 1 of length 100mm, width 10mm, and thickness 1.2mm, respectively.

At this time, the shape of the opening part 28 and the recessed part 26 changes the shape of the metal mold | die for punching the opening part 28 with respect to the edge part 28e which spreads over four sides to the rectangular opening part 28, and is C surface. Alternatively, the size of the R plane was changed to 0.01 mm, 0.03 mm, 0.05 mm, 0.10 mm, 0.20 mm, 0.30 mm, 0.50 mm.

Then, electroless Ni plating was applied to the surface of the extraction electrode 27 exposed to the opening 28, and then a Ni wire having a diameter of 0.6 mm was soldered using Ag-Cu solder (BAg-8).

An aluminum plate having a length of 110 mm, a width of 12 mm, and a thickness of 5 mm is provided on both surfaces of the ceramic heater 21 thus prepared so as to cover the entire ceramic heater 21, and closely adhered to each other at the center of the ceramic heater 21. As a test for acceleration, the cycle was repeated for 3000 cycles by applying a voltage for 5 minutes so that the maximum temperature of the ceramic heater 21 was 300 ° C., injecting air for 5 minutes, and forcibly cooling the whole to 40 ° C. or less. The change in the tensile strength of the lead member 24 of the ceramic heater 1 was confirmed.

Tensile strength is shown in Table 3 with the average of N = 10, respectively.

Table 3

* Is outside the claims of the present invention.

As can be seen from Table 3, the tensile strength after the endurance test was reduced to 30 N or less for Nos. 46 and C for which C chamfering was not performed, and Nos. 47 and 48 whose C chamfering dimensions were less than 0.05 mm.

In contrast, Nos. 49 to 53 with a C chamfer dimension of 0.05 mm or more showed a strength of 40 N or more.

Further, Nos. 51 to 53 with a C chamfer dimension of 0.2 mm or more exhibited strengths of about 60 N. The same results were obtained for Nos. 55 and 56 in which the C chamfers were changed to R chamfers. The tensile strength after that fell to 30 N or less.

Example 3

Here, in the opening 28 of the ceramic heater 21, the ratio of the outer circumference of the extraction electrode 27 embedded in the ceramic body 22 is changed to 30%, 50%, 70%, 90%, and the ceramic In the heater 21 unit alone, the ceramic heater 21 was put in a constant temperature bath at 400 ° C for 10 minutes to stabilize the temperature, and after taking out, a thermal cycle test was performed for 2000 cycles to inject air for 5 minutes to cool down to 40 ° C or less. The tensile strength of the member 24 was measured.

In the tensile test, the end of the lead member 24 was pulled in the direction perpendicular to the peripheral surface of the ceramic heater 21 to measure its peel strength.

Furthermore, as the lead member 24, a 0.6 mm diameter Ni wire was used, and as the soldering material 25, Ag-Cu lead (BAg-8) was used.

Tensile strength was taken as the average of N = 10, respectively, and about the preparation method of a sample, the result produced by the method similar to Example 2 is shown in Table 4.

Table 4

As can be seen from Table 4, the No. 57 having a 30% outer circumference ratio of the extraction electrode 27 embedded in the ceramic substrate 22 had a peel strength of 20 N of the lead member 24 after the endurance test, but more than 50%. Nos. 58 to 60 exhibited good tensile strength of 50 N or more.

Example 4

Here, the angle θ formed between the wall surface 22s of the opening 28 of the ceramic heater 21 and the extraction electrode 27 and the tensile strength of the lead member 24 after the thermal cycle endurance test were measured.

The sample which changed the angle (theta) by 50 degree, 60 degree, 80 degree, 90 degree, 100 degree, 110 degree, 120 degree was prepared.

The endurance test was evaluated in the same manner as in Example 3, n = 10 was evaluated, respectively, and the results of describing the average as data are shown in Table 5.

Table 5

As can be seen from Table 5, No. 61 having an angle θ of 50 degrees has a tensile strength of 50 N or less after the endurance test, and No. 67 having an angle θ of 120 degrees has a tensile strength of 50 N or less. No. 62-66 which is 60-110 degree showed the favorable value of 60 N or more of tensile strength.

Example 5.

Here, the relationship between the thickness of the extraction electrode 27 and the tensile strength after the endurance test was investigated.

20 samples each having the thickness of the extraction electrode 27 changed to 5 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, and 100 μm were prepared, and the durability evaluation was evaluated in the same manner as in Example 3. One result is shown in Table 6.

Table 6

As can be seen from Table 6, No. 68 having a thickness of the extraction electrode 27 at 5 mu m was lowered to 30 N in tensile strength after the endurance test, but No. 69 to 74 having a thickness of 10 to 100 mu m had good durability. Indicated.

Especially, No. 70-74 which made the said thickness 20 micrometers or more showed the strength of 60N or more.

Example 6.

Example 6 according to the present invention is an example related to the third embodiment.

Composed mainly of Al ₂ O _3, and preparing the rock to adjust a ceramic sheet (22a) so your total less than 10% by weight of SiO _2, CaO, MgO, ZrO _2, and made of W on a surface of the ceramic sheet (22a) The paste 10 was printed as shown in FIG. 3B to form the heat generating resistor 23 and the extraction electrode 27.

Next, the opening 28 and the concave portion 26 are formed in a separate ceramic sheet 22b, the ceramic sheet 22b is overlaid on the ceramic sheet 22a, and then fired in a reducing atmosphere at 1600 ° C. 20 ceramic heaters 21 each having a length of 100 mm, a width of 10 mm, and a thickness of 1.2 mm were prepared.

Then, an electroless Ni plating having a thickness of 5 µm was applied to the surface of the extraction electrode 27 exposed to the opening 28, and the Ni wire having a diameter of 0.6 mm was soldered using Ag-Cu solder (BAg-8).

Moreover, the sample which carried out electroless Cr plating instead of electroless Ni plating was also evaluated.

At this time, soldering conditions were carried out by dividing the temperature into 800 ° C., 850 ° C., 900 ° C., and storage time by 0.5 hours, 1 hour, 2 hours, and 5 hours, respectively.

And in order to confirm durability in continuous use, the initial tensile strength and the tensile strength after 400 degreeC x 800 hours of continuous energization were measured. In the tensile test, the end of the lead member 24 was pulled in a direction perpendicular to the main surface of the ceramic heater 21 to measure its peel strength.

In addition, the cross section of each lot was observed with the electron microscope, and the structure of the vicinity of the interface of the extraction electrode 27 and the brazing material was confirmed.

As the lead member 24, a Ni wire having a diameter of 1.0 mm was used.

The results are shown in Table 7 (Table 7-1, Table 7-2).

Table 7

Table 7-1

* Is outside the claims of the present invention.

Table 7-2

* Is outside the claims of the present invention.

As can be seen from Table 7, Nos. 75 and 79, in which the three-layer structure shown in Fig. 6 is not shown near the interface between the takeout electrode 27 and the brazing material, the tensile strength after the endurance test decreased to 200 N or less, but near the interface. Nos. 76, 77, 78, and 80 to 87 in which a three-layer structure was shown were obtained with a high tensile strength of 200 N or more.

Example 7

Example 7 which concerns on this invention is also an Example concerning Embodiment 3, Here, the thickness of a plating layer was adjusted to 1, 2, 4, 8, 12 micrometers, and the influence was confirmed by the endurance test.

As a brazing material, using BAg-8 of Ag-Cu solder, it processed by 900 degreeC x 1 hour, and soldered. Otherwise, the sample as shown in Table 8 was produced similarly to Example 6.

An aluminum plate having a length of 110 mm, a width of 12 mm, and a thickness of 5 mm was installed on both surfaces of the ceramic heater 21 thus prepared so as to cover the whole ceramic heater 21, and fixed to the center of the ceramic heater 21 in close contact with each other. As an accelerated test, a voltage was applied for 5 minutes so that the maximum temperature of the ceramic heater 21 was 300 ° C., and the air cycle was repeated for 3000 cycles in which the air was blown for 5 minutes to force air cooling to 40 ° C. or lower. The resistance change of the heater 21 was confirmed.

In addition, the manufacturing method of the sample was produced by the method similar to Example 6.

The results are shown in Table 8.

Table 8

As can be seen from Table 8, No. 88 having a plating thickness of 1 μm was obtained only by tensile strength of 100 N or less after the endurance test, while Nos. 89 to 92 having a plating thickness of 2 to 12 μm were 100 N after the endurance test. The above good tensile strength was shown.

Claims (18)

Ceramic gas; A heat generating resistor embedded in the ceramic base; An external electrode having a thickness of 5 to 200 μm electrically connected to the heat generating resistor and provided on a surface of the ceramic base; And And a lead member soldered to the external electrode. The ceramic heater of claim 1, wherein a width of the external electrode is greater than a width of the lead member. The ceramic heater according to claim 1 or 2, wherein the external electrode contains an additive composed of the same component as the main component of the ceramic base. 4. The ceramic heater according to claim 3, wherein the mixing ratio of the additive in the external electrode is 1 to 30% by weight. Ceramic gas; A heat generating resistor embedded in the ceramic base; It is electrically connected to the heat generating resistor, is provided on the surface of the ceramic substrate, has a thickness of 5 to 50 µm, and contains an additive composed of the same component as the main component of the ceramic substrate at a blending ratio of 1 to 10% by weight. External electrode; And And a lead member soldered to the external electrode. The ceramic heater according to any one of claims 1 to 5, wherein the ceramic base is cylindrical or cylindrical. The ceramic heater according to any one of claims 1 to 6, wherein the main component of the ceramic base is alumina or silicon nitride. The ceramic heater according to any one of claims 1 to 7, wherein the external electrode contains tungsten or a tungsten compound as a main component. The oxygen sensor provided with the ceramic heater as described in any one of Claims 1-8. Ceramic gas; A heat generating resistor embedded in the ceramic base; And An extraction electrode exposed from an opening formed in the ceramic base and electrically connected to the heat generating resistor, At least a part of the wall surface edge part in the said opening part, and / or at least one part of the outer periphery upper end part in the said opening part is one or more selected from the group which consists of C surface of 0.05 mm or more of chamfer dimensions, or R surface of 0.05 mm or more of radius. Ceramic heater. The ceramic heater according to claim 10, wherein at least 50% of the outer circumference of the extraction electrode in the opening is embedded in a ceramic base. 12. The ceramic heater according to claim 11, wherein an angle θ formed between the wall surface of the opening portion and the surface of the extraction electrode embedded in the ceramic base is set to 60 to 110 degrees. The ceramic heater according to any one of claims 10 to 12, wherein the thickness of the extraction electrode is set to 10 µm or more. The ceramic heater according to any one of claims 10 to 13, wherein a plating layer is formed on the extraction electrode. Ceramic gas; A heat generating resistor embedded in the ceramic base; An extraction electrode exposed from the opening formed in the ceramic base and electrically connected to the heat generating resistor; And A lead member soldered to the surface of the extraction electrode by a brazing material, And the brazing material has a layer structure composed of three or more metal layers. The method of claim 15, wherein the metal layer comprises a first metal layer, a second metal layer and a third metal layer in order from the extraction electrode side, The first metal layer is a NiWCu layer containing Ni as a main component, the second metal layer is a NiCu layer containing Ni as a main component, and the third metal layer is a CuNi layer containing Cu as a main component. The ceramic heater according to claim 15 or 16, wherein an average thickness of the first metal layer, the second metal layer, and the third metal layer is set in a range of 2 to 30 µm, respectively. The hair iron which used the ceramic heater as described in any one of Claims 1-8 and 10-17 as a heat generating means.

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