KR20060025133A - Ceramic heater and production method therefor - Google Patents

Abstract

A ceramic heater characterized by preventing the brazing strength of lead member from lowering, whereas, in a conventional ceramic heater, when an Si amount contained in a lead member is large, glass grains are deposited on the surface of a lead member or a brazing material to produce cracks in a plating layer formed on a brazing material depending on a heat cycle when a ceramic heater is used, oxidize a brazing material or a lead member and lower the brazing strength of a lead member. The ceramic heater (7) comprises a ceramic heaing element (3) with a built-in heating resistor (2), an electrode pad (9) provided on the surface of the ceramic heating element (3) to supply a current to the resistor (2), and a plating layer (31) which is formed on the surface of the electrode pad (9) and to which a lead member (33) is attached via a brazing material (32), the amount of Si in the lead member (33) being up to 0.05 wt.%.

Description

Ceramic heater and its manufacturing method {CERAMIC HEATER AND PRODUCTION METHOD THEREFOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater for use in an automotive air-fuel ratio detection sensor heating heater, a carburetor heater, a soldering iron heater, an oxygen sensor heater, a glow plug heater, and the like, and a manufacturing method thereof.

Conventionally, as a heater for automobiles, such as an air-fuel ratio sensor heating heater, the ceramic core material 36 'as shown in FIG. 7 is coat | covered with the ceramic sheet 34', and this ceramic core material 36 'and a ceramic sheet | seat are comprised. A heat generating resistor 2 'is formed between the 34', and the ceramic heater 7 'formed by connecting the lead member 33' with the lead member 33 'so that the lead member 33' conducts with the heat generating resistor 2 '. It is used a lot. When manufacturing the cylindrical ceramic heater 7 ', as shown in FIG. 8, the ceramic core material 36' and the ceramic sheet 34 'are prepared, and W is formed on one surface of the ceramic sheet 34'. After printing a high melting point metal paste such as Re, Mo, and the like, the heat generating resistor 2 'and the electrode lead-out part 5a' are formed, and the ceramic sheet 34 'is formed so that the surface on which these are formed is inside. It wound around the core material 36 ', and the whole was sintered and it was set as the ceramic heater 7' (Japanese Patent Laid-Open No. 11-354255 (Patent Document 1) and Japanese Patent Laid-Open No. 11-257659 ( Patent document 2).

An electrode lead portion 5a 'is connected to the heating resistor 2' on the ceramic sheet 34 ', and a through hole (not shown) is formed at an end of the electrode lead portion 5a'. The electrode pad 9 'on the back side and the electrode lead-out portion 5a' are connected. A conductive paste is injected into the through hole as needed.

As shown in the partial sectional view of the periphery of the electrode pad shown in Fig. 9, the ceramic heater 7 'is formed with a plating layer 31'-1 made of Ni on the surface of the electrode pad 9' exposed to the side surface. A lead member 33 'made of Ni or the like is bonded to the surface of the plating layer 31'-1 through a solder material 32', and the heat generating resistor 2 'is energized by energizing the lead member 33'. It is a structure that generates heat.

Further, in order to prevent oxidation or sulfidation of the solder material 32 ', a plating layer 31'-2 made of Ni is formed on the surface of the solder material 32', and the plating layer 31'-2 is formed. After the heat treatment and the heat treatment at the time of soldering the lead member 33 ', the heat treatment was performed in a reducing atmosphere in which the solder material 32' was not oxidized.

However, when the heat treatment is carried out in a reducing atmosphere, since it does not contain water vapor, blackened stains or the like adhere to the surface of the ceramic heating element 3 'after the heat treatment, and this deposit is difficult to remove completely even when washed. In the case of the ceramic heater used inside the oxygen sensor, this deposit was peeled off during use, and there was a risk of deteriorating sensor characteristics by reacting with the Pt electrode formed inside the oxygen sensor.

In order to cope with this problem, by performing the soldering heat treatment in a reducing atmosphere containing water vapor, carbon residues attached to the ceramic heater 7 'by the oxygen partial pressure in the chemical equilibrium of H ₂ OH ₂ are burned off. In this case, a problem arises that the lead member 33 'easily peels. In recent years, regulations on automobile exhaust gas have become strict, and it is necessary to increase the speed of raising the oxygen sensor used for the air-fuel ratio control. Therefore, it is necessary to increase the rising characteristics of the ceramic heater 7 '. For this reason, since the use temperature of the ceramic heater 7 'became high, such a problem became remarkable.

Particularly, since high reliability is required for the ceramic heater 7 'used for automobiles, it is not preferable that any one of the above 1000 defects occur.

So, as a result of polite research to solve this problem, the following knowledge was obtained. That is, the deposition of the glass particles 37 'is found on the surfaces of the plating layer 31'-2 and the solder material 32' formed on the surface of the electrode pad 9 ', as shown in Figs. do.

The glass particles 37 'are considered to have been oxidized when Si, which is an impurity contained in the lead member 33', the ceramic heating element 3 ', and the solder material 32', seeps out and oxidizes. Si contained in the 33 'is added to remove the impurity oxygen in the lead member 33'. When oxygen remains in the lead member 33 ', this oxygen is added to the grain boundary of the lead member 33'. When the segregation occurs and stress is applied to the lead member 33 ', the lead member 33' easily breaks the grain boundary. For this reason, Si was added excessively so that oxygen might not remain in the lead member 33 ', and about 0.2 weight% of Si was contained in the lead member 33'.

By the way, when there is too much Si added to the lead member 33 ', the diffusion rate of Si in the lead member 33' is increased in the mutual diffusion of Si in the lead member 33 'and oxygen in a heat treatment atmosphere. Since it is faster than the diffusion rate of oxygen in 33 '), the glass particles 37' which are oxides of Si precipitate on the surface of the lead member 33 '. In particular, near the interface with the solder member 32 ', Si in the portion in contact with the solder member 32' is diffused and precipitated, so that the amount of generation of the glass particles 37 'is increased and the glass particles 37' are particles. To grow. When the glass particles 37 'are formed on the surface of the lead member 33', the particles grow, the amount of precipitation increases, and when the particle diameter is 100 µm or more, the oxidation prevention of the lead member 33 'is prevented. In order to prevent the plating layer 31'-2 formed on the surface of the lead member 33 'from covering the entire surface of the solder material 32', a gap is formed between the glass and the plating layer by a thermal cycle during use. The air diffuses from this gap to oxidize the solder member 32 'or the lead member 33', thereby deteriorating the adhesive strength of the solder member 32 'or the lead member 33', and thus the lead member 33 '. It will lower the soldering strength.

For example, as shown in Figs. 10 and 11, if the glass particles 37 'are present on the surface of the Ag-Cu-based solder material 32', the solder material 32 'is formed by the thermal cycle during use of the ceramic heater. The oxidized component such as Cu present starts to oxidize, and reaction occurs in which needle-shaped crystals 32a 'made of oxides of Cu precipitate on the surface, which penetrates into the interior of the solder material 32', It was found that the lead member 33 'was peeled off from that point.

The present invention has been devised based on the above-described findings, and its object is to suppress oxidation in the electrode pad 9 of the ceramic heater 7 and to improve the bonding strength of the lead member 33, thereby improving durability. It is to provide a good ceramic heater (7).

An object of the present invention is a ceramic heater in which a heat generating resistor is incorporated in a ceramic heating element, and a lead member is attached to the ceramic heating element so as to conduct electricity with the heat generating resistor and the lead member, wherein the amount of Si in the lead member is 0.05 weight. It is achieved by making it into% or less. According to the ceramic heater according to the present invention, since the amount of Si in the lead member is 0.05% by weight or less, the maximum particle diameter of the glass particles is 100 µm or less, and the area ratio of the glass particles is 0.5% or less, and the durability This good ceramic heater can be obtained.

The ceramic heater may also be used for an oxygen sensor or a glow plug.

In addition, in the method of manufacturing a ceramic heater of the present invention, a heating resistor is embedded in a ceramic heating element, an electrode pad for energizing the heating resistor is provided on the surface of the ceramic heating element, and a plating layer is formed on the surface of the electrode pad. A method of manufacturing a ceramic heater formed by attaching a lead member through a solder material, wherein an electrode pad is formed on a ceramic heating element incorporating a heat generating resistor, a plating layer is formed on the surface of the electrode pad, and a steam partial pressure is reduced in a low temperature region. A lead member is joined through a solder material by a heat treatment having an elevated first heat treatment step and a second heat treatment step in which the water vapor partial pressure is reduced in a high temperature region.

According to the manufacturing method of the ceramic heater which concerns on this invention, it turned out that the maximum particle diameter of a glass particle can be 100 micrometers or less, the area ratio of glass particle can be 0.5% or less, and it can be set as the ceramic heater with favorable durability.

Moreover, in the manufacturing method of the ceramic heater of this invention, the said 1st heat processing process is the temperature 200 degreeC or more and less than 600 degreeC, the steam partial pressure 900 kPa or more and 2400 kPa or less, and the 2nd heat treatment process is the temperature 600 degreeC or more and less than 1000 degreeC, and steam It is preferable to carry out at a partial pressure of 900 Pa or less. This makes it possible to stably supply a ceramic heater having a particle diameter of 100 µm or less without streaking on the surface of the ceramic heater and to obtain a ceramic heater having very good durability of the lead member.

1 is a perspective view showing one embodiment of a ceramic heater of the present invention.

FIG. 2 is an exploded perspective view of the ceramic heater of FIG. 1.

3 is a partially enlarged view showing a defect of the heat generating resistor of FIG.

4 is a partial perspective view of the periphery of an electrode pad used in the ceramic heater of the present invention.

FIG. 5 is a partially enlarged view of the surface of the solder material around the electrode pads of the ceramic heater of FIG. 4.

FIG. 6 is an enlarged cross-sectional view of a portion of the electrode pad periphery of FIG. 4.

7 is a perspective view showing a conventional ceramic heater.

8 is an exploded perspective view of a conventional ceramic heater.

9 is a partial cross-sectional view around the electrode pad of a conventional ceramic heater.

10 is an enlarged view showing a mode in which a solder material used for a conventional ceramic heater is oxidized.

11 is a partial perspective view showing the form of oxidation of the solder material around the electrode pad of the conventional ceramic heater.

12 is a cross-sectional view of a ceramic heater having different porosities between the ceramic sheet and the ceramic core material.

FIG. 13 is a schematic overall view of the ceramic heater of FIG. 12.

14 is a cross-sectional view showing the migration of a conventional ceramic heater.

15 is a cross-sectional view of a ceramic heater having heat generating resistors having different line widths.

16 is a conceptual diagram showing a pattern of a heat generating resistor of a ceramic heater.

17 is a cross-sectional view showing another embodiment of a ceramic heater having a heat generating resistor having a different line width.

18 is a cross-sectional view showing an embodiment of the oxygen sensor.

19 is a cross-sectional view of a conventional ceramic heater having the same line width.

Fig. 20 is a cross sectional view of an essential part in which the ceramic heater of the present invention is applied to a glow plug used in a diesel engine, and is a sectional view of the ceramic heater composed of an attachment member having a larger diameter than the cylindrical member.

Fig. 21 is a sectional view showing a state in which a cylindrical member and an attachment member are separated as a ceramic heater composed of an attachment member having a diameter larger than that of the cylindrical member.

Fig. 22 is a sectional view of an essential part in which the ceramic heater of the present invention is applied to a glow plug used in a diesel engine, and is a sectional view of the ceramic heater composed of an attachment member having a smaller diameter than the cylindrical member.

FIG. 23 is a cross-sectional view showing a ceramic heater composed of an attachment member having a smaller diameter than the cylindrical member, wherein the cylindrical member and the attachment member are separated.

FIG. 24 is a sectional view of an essential part in which a conventional ceramic heater is applied to a glow plug used in a diesel engine, and is a sectional view of the ceramic heater after assembly.

FIG. 25 is an essential part of a conventional ceramic heater applied to a glow plug used in a diesel engine, and is a sectional view of the ceramic heater before assembly.

Fig. 26 is a main part applied to a glow plug using another conventional ceramic heater for a diesel engine, and is a sectional view of the ceramic heater after assembly.

Fig. 27 is a main part applied to a glow plug using another conventional ceramic heater for a diesel engine, and is a sectional view of the ceramic heater before assembly.

Fig. 28 is a diagram showing a method for measuring cantilever strength, temperature rising characteristics, and airtight characteristics.

1 is a partially notched perspective view of the ceramic heater 7, and FIG. 2 is a developed view of the ceramic heating element 3.

As shown in FIG. 1, the ceramic heater 7 of the present invention incorporates a heat generating resistor 2 into the ceramic heat generating body 3, and supplies an electrode pad 9 that conducts electricity to an end of the heat generating resistor 2. It is provided on the surface of 3), the plating layer 31 is formed in the electrode pad 9, and the lead member 33 is joined through the solder material 32 '.

As shown in FIG. 2, the ceramic heater 7 includes an electrode pad (not shown) formed on the surface of the ceramic sheet 34 and having an electrode lead portion 5a formed thereon, and formed on the rear surface side thereof. It has a structure in which a through hole is bonded between 9).

The ceramic heating element 3 incorporating the heat generating resistor 2 can be obtained by closely firing the prepared ceramic sheet 34 so that the heat generating resistor 2 is inside the ceramic core material 36.

(Lead member)

In the present invention, the amount of Si contained in the lead member 33 is set to 0.05% by weight or less.

Si is added to the lead member 33 to remove the impurity oxygen in the lead member 33. The reason why the impurity oxygen is removed is that when the amount of oxygen remaining in the lead member 33 is large, the grain boundary is easily broken by this oxygen. Therefore, excessive addition of Si prevented the remaining of oxygen and maintained the strength of the lead member 33. However, this excess Si is oxidized into glass and precipitates on the surface of the lead member 33 or the solder material 32 as shown in FIG. For this reason, when forming the plating layer 31 for oxidation prevention on these, the plating layer 31 is not formed in a part of glass, and it becomes a defect, and the lead member 33 and the solder material 32 are thermally cycled during use. There was a problem that is oxidized.

In order to solve the said problem, the ceramic heater which concerns on this invention is characterized by making Si contained in the lead member 33 into 0.05 weight% or less. MEANS TO SOLVE THE PROBLEM The present inventors discovered that the said structure can reduce the amount of glass produced | generated on the surface of the lead member 33 or the solder material 32 after a soldering process, and can also make the diameter small. The heat cycle during the use of the ceramic heater causes a gap between the glass formed on the surface of the lead member 33 or the solder material 32 and the plating layer 31, and oxygen diffuses from the gap, but the lead member ( When the amount of Si contained in the 33) is 0.05% by weight or less, the amount of glass generated on the surface of the lead member 33 or the solder member 32 is reduced, so that a gap is hardly formed between the glass and the plating layer 31. Therefore, oxidation of the lead member 33 and the solder material 32 can be prevented. Moreover, it is preferable to make the amount of Si into 0.03 weight% or less.

In addition, even if the amount of Si contained in the lead member 33 is very small (0.05% by weight or less), the impurities in the lead member 33 can be sufficiently removed to be of high strength.

As a method for adjusting the amount of Si contained in the lead member 33, the amount of oxygen contained in the ingot of a metal, which is a raw material, is measured before the lead member 33 is manufactured, and then added to remove the oxygen. The amount of Si to be determined is determined and the amount of Si remaining in the finally obtained lead member 33 is adjusted to 0.05% by weight or less, or the atmosphere when melting the raw material is performed in vacuum or the number of times of melting is determined. There is a method of increasing the purity of the lead member 33 repeatedly to reduce the amount of Si such as impurities. By these methods, the lead member 33 can be made high in purity, and the particle diameter of the glass particles can be reduced. In addition, the amount of Si of the said lead member 33 melt | dissolved in the acid solution which pressurized the lead member 33, and quantitatively analyzed by inductively coupled plasma emission spectroscopy (ICP).

As the lead member 33, those made of Ni, Fe-Ni-Co alloys, Fe-Ni-based alloys, various stainless steels, and the like can be used, and the shape of the lead member 33 can be a cross-sectional wire rod or plate-like shape. Various shapes, such as a wire rod and a block shape, can be used. In particular, it is preferable to use a Ni-based or Fe-Ni-based alloy having good heat resistance, and the heat transfer from the heat generating resistor 2 increases the temperature of the lead member 33 during use to effectively prevent deterioration. Can be.

When using Ni or Fe-Ni alloy as said lead member 33, it is preferable to make the average crystal grain diameter into 400 micrometers or less. When the average particle diameter exceeds 400 占 퐉, the lead member 33 near the soldered portion is fatigued and cracks are likely to occur due to vibration and thermal cycles in use. In other materials, for example, when the grain boundary of the material forming the lead member 33 is larger than the thickness of the lead member 33, the stress is generated at the grain boundary near the boundary between the solder member 32 and the lead member 33. The concentration tends to cause cracks.

In addition, as for the heat processing at the time of soldering, the temperature at the time of soldering is reduced as much as possible, and shortening processing time can make the average crystal grain diameter of the lead member 33 into 400 micrometers or less, and the strength of the lead member 33 is carried out. The fall can be prevented more.

Moreover, in order to prevent the oxidation of the solder material 32, it is preferable to form the plating layer 31 on the surface of the solder material 32 to which the lead member 33 was joined, and the plating layer ( In the case where 31) is not formed, it is preferable to plate the entire lead member 33. It is possible to prevent the lead member from being easily broken by being oxidized.

(Ceramic heater)

Hereinafter, the ceramic heater 7 will be described. The ceramic heater 7 preferably has an outer diameter of 2 to 20 mm, a length of 40 to 200 mm, and a length of 40 to 65 mm, for example.

(Ceramic sheet)

The ceramic sheet 34 constituting the ceramic heating element 3 is made of various ceramics such as aluminum oxide ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, and particularly, made of aluminum oxide ceramics. Preferably, for example, 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 1 to 3 weight of ZrO ₂ . It is preferable to use aluminum oxide ceramics containing%. When 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 heating resistor 2 incorporated in the ceramic heating element 3 decreases, and the durability of the ceramic heater 7 may be deteriorated. have.

(Heating resistor)

The ceramic heating element 3 is provided with a heat generating resistor 2, and has a high melting point metal such as W, Mo, and Re as a main component, and as shown in FIG. 3, a defect b is present in the pattern of the heat generating resistor 2. ), It is preferable to make the width t of the defect portion equal to or less than 1/2 of the pattern width t. This is because if the width t of the defect exceeds 1/2 of the pattern width t, it locally generates heat at this portion, and the resistance value of the heat generating resistor 2 becomes large, resulting in deterioration of durability.

Such defects are thought to be caused by patterns being pulled out due to dust adhering to the printed plate during printing formation of the heat generating resistor 2, or when foreign substances are mixed and lost during firing. Although there is a process of handling the raw ceramic sheet 34 in the printing and adhesion process, it is possible to improve the cleanliness of the process and to maintain the inspection process for removing the defects having the above dimensions with respect to the occurrence of any defect. It is important.

In addition, when using as a heater for automobiles, it is preferable that the heat generating length of the heat generating resistor 2 is 3 to 15 mm. If the heat generation length is shorter than 3 mm, the temperature rise during energization can be made faster, but the durability of the ceramic heater is reduced. On the other hand, when it is longer than 15 mm, the temperature increase rate becomes slow, and when the temperature increase rate is attempted to increase, the power consumption of the ceramic heater increases. Here, the heating path means the length f of the portion of the reciprocating pattern in the heating resistor 2 shown in FIG. This heat generation length f is variously selected according to a use.

As shown in FIG. 1, electrode lead portions 5a are formed at both ends of the heat generating resistor 2, and through holes 35 are formed in the electrode lead portions 5a formed at the end of the heat generating resistor 2. The electrode pad 9 for energizing the heat generating resistor 2 is connected.

(Electrode pad)

The electrode pad 9 is composed of a metallization layer composed mainly of high melting point metals such as W, Mo, and Re, and forms a plating layer 31 on the surface to improve the flow of the solder material 32 '. Improves soldering strength.

In addition, the plating layer 31 made of Ni, Cr, or a composite material containing these as a main component is formed on the surface of the electrode pad 9 to have a thickness of 1 to 5 탆, and the solder material 32 is formed on the surface of the electrode pad 9. The lead member is soldered with the solder material.

Here, FIG. 4 is a perspective view showing the junction of the lead member 33 of the ceramic heater 7 of the present invention, FIG. 5 is an enlarged partial view of the surface portion of the solder material 32 ', and FIG. The cross section is shown.

(Solder material)

The solder material 32 is composed of Ag-Cu, Au-Cu, Ag, Cu, Au, etc. as a main component, and contains a resin such as a binder or metals such as Ti, Mo, V, which are active metals, as necessary. It is melted and soldered in a reducing atmosphere containing oxygen.

Further, the solder material 32 has a soldering temperature of 1000 when Au content is 25 to 95% by weight when Au-Cu solder is used and Au content is 50 to 95% by weight when Au-Ni solder is used. The temperature can be set at about 占 폚, and the residual stress after soldering can be reduced. Thereby, even if fatigue resulting from the difference in thermal expansion between the solder material 32 and the ceramic heating element 3 occurs in the thermal cycle, the decrease in the solder strength can be suppressed.

(Manufacturing method of ceramic heater)

Next, the manufacturing method of the above-mentioned ceramic heater is demonstrated.

(1) First, a ceramic sheet 34 formed of a ceramic slurry containing aluminum oxide as a main component and containing 4 to 12% by weight of SiO ₂ , CaO, MgO, and ZrO ₂ in a total amount as a sintering aid is prepared.

(2) The ceramic sheet which forms the heat generating resistor 2 and the electrode lead-out portion 5a on one main surface of the ceramic sheet 34 by printing or transferring, and touches the back surface of the electrode lead-out portion 5a. The electrode pad 9 is similarly formed on the other main surface of 34 by a method such as printing or transferring.

(3) Next, a through hole 35 is formed between the electrode lead portion 5a and the electrode pad 9, and the through hole 35 has one or more of W, Mo, and Re as a main component. The electrode lead portion 5a and the electrode pad 9 can be electrically connected by filling the material or by coating the inner surface of the through hole 35.

(4) After that, a coat layer having a composition substantially similar to that of the ceramic sheet 34 is formed on the heat generating resistor 2 and the electrode lead-out portion 5a, and then the ceramic sheet 34 is surrounded by the ceramic core material 36. It is in close contact with each other to form a cylindrical shaped body. The resulting molded product is fired in a reducing atmosphere at 1500 to 1650 ° C. to obtain a ceramic heating element 3.

(5) Then, the plating layer 31 which consists of metals, such as Ni and Cr, is formed in the surface of the electrode pad 9 by the electroplating method or the electroless plating method.

(6) Next, the electrode pad 9 and the lead member 33 are bonded by heat treatment in a reducing atmosphere containing oxygen through a solder material 32 mainly composed of Ag-Cu or the like. In the lead member 33 of the present invention, since the amount of Si is adjusted in advance, and the lead member 33 having 0.5 wt% or less of Si is used, the lead member 33 or the solder member is merely heat treated in a reducing atmosphere containing oxygen. Since the amount of precipitation of the glass particles 37 formed on the surface of the 32 can be reduced and the particle diameter can be reduced, the plating layer 31 is formed on the entire surface of the lead member 33 or the solder material 32. It is possible to improve the durability of the ceramic heater.

(7) Next, the plating layer 31 which consists of metals, such as Ni and Cr, is formed in the surface of the solder material 32 formed in this way. Then, the ceramic heater 7 is completed by soldering the lead member 33 in a reducing atmosphere containing oxygen.

In addition, the soldering temperature is specifically performed at 770 to 870 DEG C for Ag-Cu solder, 950 to 1050 DEG C for Au-Cu solder, and 1000 to 1100 DEG C for Ag solder.

In addition, when the ceramic heater 7 is used in an atmosphere with high humidity, the occurrence of migration can be suppressed by using the Au-based or Cu-based solder material 32.

Moreover, as shown in FIG. 4, it is preferable to make the distance k from the tip of the electrode pad 9 to the tip of the solder material 32 at least 0.2 mm or more. If the distance k is less than 0.2 mm, the end of the electrode pad 9 is pulled out at the time of contraction of the solder material 32, and is easily peeled off, and the soldering strength is lowered.

Next, another embodiment of the ceramic heater of the present invention will be described. In the above embodiment, by using the lead member 33 having a small amount of Si, grain growth of the glass particles 37 deposited on the surface of the solder material 32 is suppressed, and the plating layer 31 having no defects on the surface thereof is suppressed. ) To form a highly durable ceramic heater 7, but in this embodiment, even when the amount of Si contained in the lead member 33 is large, the glass particles 37 are controlled by controlling the heat treatment conditions during soldering. The amount of precipitates is reduced to suppress grain growth.

As the heat treatment conditions, as shown in FIG. 4, a first heat treatment step in which a plating layer 31 is formed on the surface of the electrode pad 9 formed on the ceramic heating element 3 and the water vapor partial pressure is raised in the low temperature region, and the high temperature region The lead member 33 is joined through the solder material 32 by a heat treatment having a second heat treatment step in which the water vapor partial pressure is reduced.

Thus, by dividing the furnace to be subjected to heat treatment into a plurality of zones, increasing the partial pressure of steam in the low temperature region and lowering the partial pressure of steam in the high temperature region, thereby reducing the equilibrium oxygen partial pressure in the furnace, which is generated by the separation between the hydrogen and oxygen. The oxidation of Si contained in the lead member 33 can be suppressed, and the diameter of the glass particles 37 due to Si contained in the lead member 33 or the solder member 32 can be reduced.

In particular, it is preferable that the temperature of 200 ° C. or more and less than 600 ° C., the steam partial pressure 900 ° C. or more and 2400 kPa or less as the first heat treatment step, and the temperature of 600 ° C. or more and less than 1000 ° C. and the steam partial pressure 900 ° C. or less as the second heat treatment step.

In the first heat treatment step (temperature of 200 ° C. or higher and less than 600 ° C.), the Si in the lead member 33 and the solder material 32 has a low reaction rate of oxidation, so that the glass particles 37 shown in FIGS. It doesn't grow much. Therefore, in the temperature range below 600 ° C, by increasing the vapor atmospheric pressure to 900 kPa or more and 2400 kPa or less, the oxygen partial pressure from the water vapor in the atmosphere is increased to give priority to combustion removal of organic matter attached to the ceramic heating element 3 surface. .

Here, when the water vapor partial pressure is less than 900 kPa, organic matter cannot be completely burned out. On the other hand, if it exceeds 2400 kPa, the surface of metal members such as the plating layer 31, the solder material 32, the lead member 33, and the like is oxidized and deteriorated, or the appearance is poor.

In the second heat treatment step (temperature of 600 ° C. or higher and lower than 1000 ° C.), the solder material 32 used is dissolved and the temperature is high in the temperature range for joining the lead member 33 and the electrode pad 9. The reaction rate of oxidation of Si in the lead member 33 or the solder material 32 is high. Therefore, by reducing the water vapor partial pressure to 900 kPa or less, the oxygen partial pressure from the water vapor in the atmosphere can be reduced to suppress oxidation of Si, and the amount of precipitation of the glass particles 37 can be reduced to reduce the particle diameter. The lower the steam partial pressure is, the better the lower the steam partial pressure is, the steam partial pressure in the gas is more preferably 450 kPa or less, and more preferably 300 kPa or less.

In addition, the water vapor partial pressure in the high temperature region is more preferably 600 Pa or less.

It is also possible to finely control the steam partial pressure between the divided zones. The steam partial pressure can be adjusted by passing the gas introduced into the soldering furnace into a previously adjusted temperature bath to obtain a saturated steam pressure. Although the temperature which gives this saturated steam pressure is called dew point, when adjusting the dew point of gas to 0 degrees C or less, what is necessary is just to cool the piping which introduces gas to predetermined temperature of 0 degrees C or less. In addition, when making a dew point more than room temperature, it is necessary to adjust to the temperature more than dew point in the piping temperature after the said water tank.

Thus, the ceramic heater using the heat treatment method which controlled the 1st heat treatment process and the 2nd heat treatment process can make the largest diameter h of the glass particle 37 which precipitates on the surface of the solder material 32 100 micrometers or less. In addition, it is possible to prevent the problem that the solder member 32 is oxidized by the thermal cycle during use, thereby reducing the tensile strength of the lead member 33. When the grain growth of the glass particles 37 cannot be prevented, as shown in FIG. 6, a portion in which the plating formed on the surface of the lead member 33 or the solder member 32 is not applied is generated and is in use. By the thermal cycle, a gap is generated between the plating layer 31 and the glass particles 37, the lead member 33 or the solder member 32 'is oxidized, and the strength of the soldered portion of the lead member 33 is deteriorated. Since the durability of a ceramic heater falls, it is unpreferable. In particular, it is more preferable that the maximum diameter h of the glass particles 37 is 30 μm or less, particularly 10 μm or less, so that the durability of the tensile strength of the lead member 33 can be improved.

Here, the largest diameter of the glass particles 37 refers to a long diameter when the shape is elliptical, and a long diameter in the projection view when the glass particles 37 are directly viewed when the shape is substantially dome. As a measuring method of the largest diameter h of the said glass particle 37, it can measure by observing arbitrary area | regions, using apparatuses, such as a metal microscope, a major scope, and an electron microscope. Also, in order to increase the accuracy, it is preferable to increase the measurement area to a plurality.

In addition, the ceramic heater 7 of this invention is not limited to the above-mentioned embodiment, A various change is possible as long as it is in the range which does not deviate from the summary, In particular, as described in 1st Embodiment, It is also possible to use the lead member 33 which reduced content.

(Porosity of Ceramic Core and Ceramic Sheet)

Moreover, it is preferable to make the average pore diameter of the said ceramic core material 36 and the said ceramic sheet 34 into 1-10 micrometers. In particular, it is preferable to make the porosity of the said ceramic core material below the porosity of the said ceramic sheet | seat. Moreover, when porosity of the said ceramic core material is A and porosity of the said ceramic sheet | seat is B, it is preferable that it is 0.3 <= A / B <= 0.95.

As shown in FIG. 14, under the condition of applying a DC voltage, migration in which cations contained in the substrate of the ceramic heating element 3 move from the anode side 38a to the cathode side 38b occurs by this voltage. Due to this migration, positive ions collect on the cathode side 38b over time, and on the contrary, the anode side 38a changes to a poor state over time. The oxygen in the atmosphere diffuses near the heat generating resistor 2 on the anode side 38a, and the heat generating resistor 2 is oxidized and disconnected.

Conventionally, about the pore diameter of the general ceramic core material 36, the ceramic substrate for semiconductor manufacturing and inspection apparatus whose maximum pore diameter of a ceramic is 50 micrometers or less, for example is proposed (Japanese Patent Laid-Open No. 2001-298074 (Patent Document) 3)).

Moreover, in order to make it hard to produce the migration which causes the disconnection of the ceramic heater 7, it is proposed that it is effective to add the component which is hard to cause migration to the electrode lead-out part 5 connected to the heat generating resistor 2. (Japanese Patent Laid-Open No. 1997-245946 (Patent Document 4)).

Recent trends with respect to the ceramic heater 7 include rapid heating to improve the exhaust gas detection capability, as shown in the heater for oxygen sensor heating for automobiles, vibration resistance, strength, and guarantee due to the compactness of the vehicle. The demand for long life to extend the period becomes stronger. Specifically, there is a flow to reduce the electric current flowing through the wiring by setting the vehicle power supply to 42V to reduce the line diameter of the wiring member to reduce the number of parts to reduce the weight.

The damage generated by this is ion migration generated by an electric field. When the ceramic heater 7 is used at a high temperature, alkali metals such as Na and K contained as components and impurities such as Ca, Mg and Si in the ceramic heating element move by the electric field. This ion movement is accelerated as the voltage applied to the ceramic heater 7 increases, so that the movement amount increases. Thereby, there exists a problem that the resistance value of the heat generating resistor 2 increases, the durability of the heat generating resistor 2 is reduced, and further, the heat generating resistor 2 is disconnected.

Here, the ceramic heater described in patent document 3 is a ceramic substrate for semiconductor manufacturing and inspection apparatus which ensures a withstand voltage in order to add electrically conductive carbon to a ceramic substrate, and differs from the field with this invention in the subject, and is immediately converted. It is not possible.

In addition, in Patent Literature 4, in order to make it difficult to cause migration that causes disconnection of the ceramic heater 7, a component that is hard to cause migration is added to the electrode lead-out portion 5 connected to the heat generating resistor 2. Although the effective thing is proposed, there existed a problem that sinterability worsens.

In view of the above, the surface of the ceramic sheet is screen printed with a heating resistor and an electrode lead portion connected to the heat generating resistor, and an electrode pad for conducting the electrode lead portion to the back surface opposite to the electrode lead portion. In the ceramic heater in which the sheet is in close contact with the ceramic core material with the surface inside, the average heater diameter of the ceramic core material and the ceramic sheet is preferably 1 to 10 µm. The porosity of the ceramic core may be equal to or less than the porosity of the ceramic sheet. When the porosity of the ceramic core is A and the porosity of the ceramic sheet is B, 0.3? A / B? 0.95.

With the above configuration, it is possible to obtain a trapping volume of the cation and to obtain a ceramic heater having improved durability against disconnection of the heat generating resistor due to migration of the cation.

(Oxygen sensor)

As shown in FIG. 15, the heat generating resistor 2 formed on the ceramic sheet 34 is divided into three in the longitudinal direction of the pattern, and the average of the line widths of the center portions of the heat generating resistors is Ps and the average of the line widths of both ends is Po. A ceramic heater in which the line width of the heat generating resistor 2 is adjusted so that Ps < Po may be used for the oxygen sensor.

As shown in Fig. 19, in the conventional ceramic heater 7, the line width P of the built-in heat generating resistor 2 is uniformly formed.

In recent years, with the tightening of the exhaust gas regulation, it is necessary to improve the synergistic characteristics during cold start, and there is a demand for a highly durable ceramic heater 7 that can be used even at a high temperature of 800 ° C or higher. However, when the heat generation amount of the ceramic heater 7 is increased to shorten the temperature increase time, especially during cold start when the engine is cold, the time after voltage is applied becomes long, so that an overshift of temperature occurs and the oxygen sensor 43 The problem was that the electrode was damaged, the durability of the ceramic heater 7 was lowered, or the temperature of the electrode pad 9 was increased and disconnected.

In order to solve such a problem, a heat pattern having an arbitrary shape and thickness to be the heat generating resistor 2 integrally with the electrode extraction section 5 is printed on the ceramic sheet 34 mainly composed of aluminum nitride. A ceramic heater 7 is proposed in which a conductive material having a larger temperature resistance coefficient than that of the heat generating resistor 2 is connected in series with the heat generating resistor 2 (Japanese Patent Laid-Open No. 8-273813 (Patent Document 5)). ).

In addition, when heating this oxygen sensor with the ceramic heater 7, it was provided in the center part 40a of the ceramic heater 7 so that the oxygen sensor 43 may be heated uniformly in the circumferential direction. However, in order to direct the early operation of the oxygen sensor 43 during engine cold start, it is not necessary to uniformly heat the entire circumferential direction, and it is shown that it works sufficiently when a part of the oxygen sensor 43 is heated (Japan). Patent Publication No. 2000-193633 (Patent Document 6).

Incidentally, when the ceramic heater 7 is rapidly heated, cracks are shown in the highest temperature portion, and in order to mitigate thermal shock during the rapid temperature rise and to prevent the occurrence of cracks on the surface of the ceramic heater 7, It is proposed to make the line width of the outer side of the heat generating resistor 2 narrower than the center part 40a, and to make small the temperature distribution of the circumferential direction of a heat generating part (Japanese Unexamined-Japanese-Patent No. 2001-15252 (patent document 7)).

By the way, since the line width P of the heat generating resistor 2 is formed uniformly, the ceramic heater 7 shown by patent document 6 had a problem from the viewpoint of rapid temperature rising.

On the other hand, in Patent Literature 7, it is possible to prevent cracks from occurring on the surface of the ceramic heating element. However, since the line width P of the outer side 40b of the heating resistor 2 is narrowed, the durability of the ceramic heater 7 is problematic. There was.

Thus, in a ceramic heater formed by integrally firing a ceramic sheet formed by forming a heat generating resistor on one main surface of the ceramic sheet, the heat generating resistor formed on the ceramic sheet is divided into three equal parts in the longitudinal direction of the pattern. When the average of the line width of the center portion of the heat generating resistor is Ps and the average of the line widths of both ends is Po, it is preferable that the ceramic heater is characterized by Ps <Po. The ceramic heater may also be used for an oxygen sensor.

Further, when the line width of the center portion of the heat generating resistor formed on the ceramic sheet is set to P1, and the line width is set to P2, ..., and Pn in order toward the outside, P1 < P2 &lt; It is good also as a ceramic heater characterized by the above-mentioned.

The ceramic heater may be characterized in that the line width P1 of the heat generating resistor is 50 to 95% with respect to Pn.

In addition, you may provide so that the highest temperature part of a heat generating resistor formation part may contact with the inner wall of an oxygen sensor, or may be within 0.5 mm.

According to the present invention, in the ceramic heater formed by integrally firing the ceramic sheet formed by forming the heat generating resistor on one main surface, the main surface is in close contact with the ceramic core material, the heat generating resistor formed on the ceramic sheet is divided into three parts. When the average of the line width of the center portion of the heat generating resistor is Ps and the average of the line widths of the both ends is set to Ps < Po, an oxygen sensor having good durability and good temperature rising characteristics can be provided.

In the ceramic heater formed by integrally firing a ceramic sheet formed by forming a heat generating resistor on one main surface of the ceramic sheet, the line width of the heat generating resistor in the center of the ceramic sheet is set to P1. P1, P2 < = Pn, P1 &lt; Pn, and the line width P1 of the heat generating resistor is 50 to Pn. 95% and the maximum temperature portion of the heat generating resistor forming portion of the ceramic heater of the present invention is provided in contact with the inner wall of the oxygen sensor or close to within 0.5 mm, thereby providing an oxygen sensor with good durability and good temperature raising performance. have.

(Glow plug)

The ceramic heater 7 can be used as a glow plug for starting the diesel engine.

It is a glow plug used for the start-up of diesel engines and various ignition and heating heaters, which enables rapid heating up in a short period of time, no radio interference, and ensures ignition for a long time regardless of the safety and atmosphere. As a highly reliable heater having excellent durability, a ceramic heater in which a heat generating resistor made of an inorganic conductive material is embedded in a ceramic sintered body has been widely used.

24 and 25, the ceramic heater generally includes a heat generating resistor 42 made of a high melting point metal such as tungsten (W), molybdenum (Mo), or a compound thereof. The ceramic heat-generating element 43 which is embedded inside or calcined and integrally formed by printing a heat-resisting resistor paste mainly composed of the high melting point metal or a compound thereof in the ceramic heat-generating element 43 is joined to the cylindrical member 46, One end (not shown) of the electrode lead-out portion embedded in the ceramic heating element 43 is electrically connected, and the cylindrical member 46 is joined to the attachment member 58 to form a negative electrode.

On the other hand, the other end (not shown) of the electrode lead-out part is connected to the terminal rod 66 through the lead wire 54 welded to the cap-shaped electrode extraction member 62 mounted on the rear end side 44 of the ceramic heating element 43. It is comprised so that it may be connected and become a positive electrode.

In this case, generally, the ceramic heating element 43 is solder-bonded to the cylindrical member 46 using a high melting point solder material so as to withstand the high temperature combustion gas and the high temperature atmosphere of the engine or various combustion heating devices. Since the member 46 is not directly exposed to the high temperature combustion gas or the high temperature atmosphere, it is soldered and bonded to the attachment member 58 using a low melting point solder material (Japanese Patent Laid-Open No. H1-029426 (Patent Documents) 8)).

By the way, the ceramic heater 7 is a ceramic heating element 43, the tubular member 46, the tubular member 46 and the attachment member 58 even when any one of a high melting point solder material and a low melting point solder material is used. Since the solder joint of the ()) is locally heated and joined, a tensile stress acts on the ceramic heating element 43 from the thermal expansion difference between the cylindrical member 46, the attachment member 58, and the ceramic heating element 43, and thus the ceramic heating element 43. ) Was broken. Further, even when large cracks are not generated in the ceramic heating element at the time of joining, small cracks inherent in use have developed, which may cause a problem that the heat generating resistor (not shown) in the ceramic heating element 3 is disconnected.

In addition, in order to solder-bond, a gap for flowing a solder material between the ceramic heating element 43 and the cylindrical member 46 and between the cylindrical member 46 and the attaching member 58 is required. 3) may be attached eccentrically, and when the ceramic heater is attached to the engine main body, various combustion apparatuses, and heating apparatuses, the ceramic heating element 3 is brought into contact with one side of the insertion hole of the engine or various apparatuses. ) Was also a problem.

For these problems, for example, as shown in Figs. 26 and 27, the cylindrical member 86 having the stepped portion 92 is bonded to the ceramic heating element 83, and the cylindrical member 86 is joined. The method of contacting by pressing the stepped portion 92 of the stepped through the conductive gasket (89) to the stepped sheet 96 provided on the attachment member 98 without soldering is disclosed (Japanese Patent Laid-Open No. 5). -018536 (Patent Document 9)).

By the way, in the said patent document 9, as shown to FIG. 26 and FIG. 27, the ceramic heating element 83 which bonded the cylindrical member 86 was connected to the step part of the cylindrical member 86 through the conductive gasket 89 ( 92 is contacted with the stepped sheet 96 of the attachment member 98 to connect the terminal rod 106 inserted into the insulator 104 to the rear end side 84 of the ceramic heating element 3 and attach the attachment member 98. The trailing edge 109 of the back end is caulked at the end surface 110 of the insulator 104 to pressurize the tubular member 86 and the attachment member 98 without soldering, so that the pressing direction is applied at the time of use. The paper is in a direction opposite to the direction of the gas pressure from the combustion side, and there is a concern that the degree of pressurization after joining affects the airtightness and strength in repeated use.

In addition, corresponding to various engines, the cylindrical member 86 and the attachment member 98 need to be designed and attached to the engine, respectively, and have a problem of being connected to a higher manufacturing cost.

Therefore, in order to solve these problems, in the ceramic heater which has a cylindrical member provided with the electrode lead-out part connected with the said heat generating resistor in the rear end side of the ceramic heating element which consists of silicon nitride ceramics with a heat generating resistor at the front end, the said It is good also as a glow plug characterized by the cylindrical member being a two-stage cylindrical structure which has a taper structure part and a large diameter cylindrical part successively on the outer peripheral surface of the small diameter cylindrical part joined with the said ceramic heating element.

Moreover, you may have the fitting part which has a step part in the outer peripheral surface of the said large diameter cylindrical part, and shrinks toward an open end.

The fitting portion may be pressed into the inner circumferential surface of the attachment member having the open end surface to contact the stepped portion with the open end surface.

According to the ceramic heater and the glow plug, in the ceramic heater having a tubular member having an electrode lead portion connected to the heat generating resistor on the rear end side of the ceramic heating element made of silicon nitride ceramics having a heat generating resistor on the front end side, Shaft diameter toward the open end starting from the step of the outer circumferential surface of the large-diameter cylindrical portion of the cylindrical member having a tapered structure portion and the large-diameter cylindrical portion successively on the outer circumferential surface of the small-diameter cylindrical portion joined to the ceramic heating element. The fitting portion is pressed into the inner circumferential surface of the attachment member having the open end surface, and the stepped portion and the open end surface are brought into contact with each other. Solder joints can be excluded, and the ceramic heating element Cracking and disconnection of the heat generating resistor can be prevented.

In addition to the reduction of residual strain (stress) due to local heating at the time of conventional solder joint, the joining portion of the cylindrical member and the attachment member also reduces the release of residual strain due to heat during use, and is also attached to the ceramic heating element. Eccentricity of the member can be reduced, and damage caused by the ceramic heating element coming into contact with one of the insertion holes of the engine or various devices can be prevented.

Moreover, according to the said glow plug, since the said cylindrical member and the attachment member were made into the joining method by press-fitting, it becomes comparatively easy joining and can prevent the higher of manufacturing cost.

The positional alignment (centering) before joining by press fit can be facilitated along the fitting part naturally, and it becomes possible to manufacture a glow plug having a high coaxiality.

Moreover, since the fitting part was formed in the outer peripheral surface of the cylindrical member, the fastening force of the fitting part is strengthened by the thermal expansion of the cylindrical member in use. Long dimension control in the axial direction can be facilitated.

In addition, the tubular member can be fixed also for a large number of engines, and a glow plug can be provided comprehensively in response to easy design change of the attachment member.

According to the present invention, in a ceramic heater having an electrode lead portion connected to the heat generating resistor on the rear end side of a ceramic heating element made of silicon nitride ceramics having a heat generating resistor on the front end side, and having a cylindrical member on the electrode lead portion. Since the cylindrical member is a two-stage cylindrical structure comprising a small cylindrical portion for joining with the ceramic heating element, a tapered structure for sealing in contact with the seat face of the cylinder head of the engine, and a large diameter cylindrical portion connected to the tapered structure, Soldering by local heating by the high frequency heating coil of the tubular member and the attachment member in the vicinity of the ceramic heating element can be eliminated, and the crack of the ceramic heating element and the disconnection of the heating resistor can be prevented.

In addition, since the open end side outer peripheral surface of the large-diameter cylindrical portion has a tapered surface that is axially reduced toward the open end, and has formed an end face perpendicular to the axial direction on the enlarged diameter outer peripheral surface, it is highly coaxial at the time of assembling and joining the attachment member. It is possible to manufacture a glow plug having a degree. In addition, the tubular member can be fixed also for a large number of engines, and a glow plug can be provided comprehensively in response to easy design change of the attachment member.

Example 1

First, in order to obtain a ceramic heater sample as shown in FIG. 1, as shown in FIG. 2, SiO ₂ , CaO, MgO, and ZrO ₂ are contained within 10 wt% in total, using Al ₂ O ₃ as a main component as the ceramic heating element 3. The heat generating resistor 2 made of W-Re and the electrode lead-out portion 5a made of W were printed on the ceramic sheet 34 adjusted as possible. Moreover, the electrode pad 9 was printed on the back surface of the ceramic sheet 34. The heat generating resistor 2 was produced so as to have a pattern of four reciprocations with a heating length of 5 mm.

Then, a through hole was formed at the end of the electrode lead-out portion 5a made of W, and the paste was injected therein to obtain conduction between the electrode pad 9 and the electrode lead-out portion 5a. The position of the through hole was formed so as to enter the inside of the soldered portion when soldering.

Next, after forming a coat layer of substantially the same component as the ceramic sheet 34 on the surface of the heat generating resistor 2 and sufficiently drying, the adhesion liquid in which ceramics of substantially the same composition as the ceramic sheet 34 are dispersed. Was applied, and the ceramic sheet 34 thus prepared was brought into close contact with the periphery of the ceramic core material 36 and fired at 1500 to 1600 ° C.

Further, a plating layer 31 having a thickness of 3 μm made of Ni is formed on the surface of the electrode pad 9, and the solder content 32 made of Au-Cu is used to provide a Si content as shown in Table 1 below. Then, a lead member 33 having a diameter of 0.8 mm having Ni as a main component was soldered at 830 ° C. in a reducing atmosphere, and a 3 μm plating layer 31 made of Ni was formed on the surface thereof and heat-treated at 700 ° C.

During the soldering treatment of the plating layer 31, the H ₂ -N ₂ gas was passed through the temperature-controlled water, and the amount of oxygen in the H ₂ -N ₂ gas was adjusted by adjusting the dew point.

In addition, the amount of Si of the lead member 33 determines the amount of Si added to remove this oxygen after measuring the amount of oxygen contained in the ingot of Ni beforehand when manufacturing the lead member 33, and finally, The amount of Si remaining in the lead member 33 obtained by adjusting the resultant is adjusted, and the amount of Si in the lead member 33 is dissolved in an acid solution pressurized by the lead member 33 and subjected to inductively coupled plasma emission spectrometry (ICP). By quantitative analysis.

Then, 5 mm 2 of an electron microscope photograph of 1000 times the particle diameter of the glass particles 37 deposited on the surface after soldering was taken to the junction of the lead member 33 of the ceramic heater of each sample, and an image processing apparatus was used. The maximum diameter h of the glass particles 37 was measured. In addition, about the generation amount of the glass particle 37, the area ratio of the glass particle 37 was measured by image analysis from the electron micrograph of the surface of the junction part of the lid member 33, and the area ratio was computed.

In addition, each sample was placed in a constant temperature bath at 350 ° C. for 5 minutes, and after the temperature was stabilized, forced quenching was carried out, and a thermal cycle test was carried out for 2000 cycles. The endurance test was performed for 500 hours in a constant temperature layer at 500 ° C. After that, the change of the plating layer 31 on the surface of the solder material 32 was observed, and it was found that the product in which Cu oxide of the solder material 32 'was deposited on the plating layer 31 occurred on the plating layer 31. The part where a discoloration area | region was seen was made into (triangle | delta), and the thing which is not seen a change like oxidation was set to (circle). This test corresponds to the acceleration test of the heat cycle in use.

In addition, the tensile strength of the lead member 33 in each sample after the endurance test subjected to the heat cycle was measured by pulling the lead member 33 vertically from the surface of the ceramic heating element 3 using a tensile tester. did.

Each sample is prepared ten pieces and the average value is shown in Table 1.

As can be seen from Table 1, the samples Nos. 6 to 9 in which the amount of Si contained in the lead member 33 is 0.08% by weight or more have a maximum diameter h on the surface of the lead member 33 after soldering. It can be seen that the glass particles 37 exceeding 100 µm are precipitated and the area ratio of the glass particles 37 is large, 0.53 to 0.82%. In addition, the tensile strength after the endurance test was lowered to 18 N or less, and oxidation as shown in FIG. 10 was observed in the appearance of the lead member 33 and the solder material 32.

In contrast, in the samples Nos. 1 to 5, in which the Si content of the lead member 33 was 0.05% by weight or less, the size of the glass particles 37 was 79 µm or less, and the area ratio of the glass particles 37 was also reduced. It can be seen that it is very low, below 0.50%. In addition, the tensile strength after the endurance test is greater than 30 N, the appearance of the lead member 33 and the solder member 32, the sample No. 5 having a Si content of 0.05% by weight is part of the plating layer 31 Although the discoloration area | region was shown in FIG. 10, it was not oxidation as shown in FIG.

Example 2

Next, as shown in FIG. 1, the plating layer 31 of thickness 3micrometer which consists of Ni is formed on the surface of the electrode pad 9, and the solder material 32 which consists of Au-Cu is used similarly to embodiment mentioned above. Then, the lead member 33 containing 0.8 mm in diameter and Ni as the main component and containing 0.2% by weight of Si is soldered under heat treatment conditions as shown in Table 2, and the plated layer 31 having a thickness of 3 mu m made of Ni is formed on the surface thereof. Was formed at the end and heat-treated at 700 ° C.

The heat treatment conditions of the lead member 33 are below 600 ° C. as the first heat treatment step and 600 to 1000 ° C. as the second heat treatment step, and the water vapor partial pressure is passed through a previously adjusted temperature bath to provide various types of water vapor as the saturated water vapor pressure. It adjusted by generating the gas adjusted by partial pressure in a furnace.

Then, 5 mm 2 of an electron microscope photograph of 1000 times the particle diameter of the glass particles 37 deposited on the surface after soldering was taken to the junction of the lead member 33 of the ceramic heater of each sample, and an image processing apparatus was used. The maximum diameter h of the glass particles 37 was measured. In addition, about the generation amount of the glass particle 37, the area ratio of the glass particle 37 was measured by image analysis from the electron micrograph of the surface of the junction part of the lid member 33, and the area ratio was computed.

In addition, the surface of the ceramic heating element in each sample was observed by Auger analysis, and the presence or absence of adhesion (organic matter) of the surface of the ceramic heating element was examined.

In addition, each sample was placed in a 350 ° C. thermostat for 5 minutes, and after the temperature was stabilized, forced quenching was carried out, followed by a 2000 cycle thermal cycle test in which it was placed in a thermostat. . Then, the change of the plating layer 31 on the surface of the solder material 32 was observed by SEM (electron microscope), and the product which the oxide of Cu of the solder material 32 precipitated in the plating layer 31 generate | occur | produced x, Part of the plated layer 31 in which discolored regions were seen was Δ, and no change such as oxidation was observed. This test corresponds to the acceleration test of the heat cycle in use.

In addition, the tensile strength of the lead member 33 in each sample after the endurance test subjected to the heat cycle was measured by pulling the lead member 33 vertically from the surface of the ceramic heating element 3 using a tensile tester. did.

Each sample is prepared ten pieces and the average value is shown in Table 2.

As can be seen from Table 2, in the method of manufacturing the ceramic heater, the first heat treatment step in which the heat treatment at the time of joining the lead member 33 through the solder material 32 does not increase the water vapor partial pressure in the low temperature region. And a sample (No. 10) having a high water vapor partial pressure in both the low temperature region and the high temperature region among the samples (No. 1, 2, 10, and 15) subjected to the second heat treatment process that does not lower the water vapor partial pressure in the high temperature region. Sample No. 15, which has no heat treatment step and has a high water vapor partial pressure at a high temperature, has a maximum diameter h of all the precipitated glass particles 37 of 110 µm or more and an area ratio of the glass particles 37. The strength of the lead member 33 after the endurance test was very large at 0.72% or more, and greatly decreased to 16N or less, and an oxide was formed on the surface of the plating layer 31 after the endurance test to show discoloration and defects.

In addition, samples (No. 1 and 2) having low water vapor partial pressures in both the low temperature region and the high temperature region have less precipitation of glass particles due to the low water vapor partial pressure in the high temperature region, but the ceramic heating element because of the low water vapor partial pressure in the low temperature region. (3) It was found that the organic matter attached to the surface could not be completely burned off.

On the other hand, the sample which has the heat processing at the time of joining a lead member through a solder material has the 1st heat processing process which raised the steam partial pressure in the low temperature area | region, and the 2nd heat processing process which reduced the steam partial pressure in the high temperature area | region ( Nos. 3 to 9 and 11 to 14 have a maximum diameter (h) of the glass particles 37 of 58 µm or less, an area ratio of 0.36% or less, no contamination of the ceramic heating element, and a plating layer in the external inspection after the endurance test. There was no oxide on the surface of (31). In addition, the tensile strength of the lead member 33 after the endurance test was larger than 30N.

Particularly, samples having a steam partial pressure of 900 kPa or more and 2400 kPa or less in the low temperature region as the first heat treatment process, and a steam partial pressure of 900 kPa or less in the high temperature region as the second heat treatment process (Nos. 4 to 8 and 11 to 13). The maximum diameter h of the glass particles 37 was 41 µm or less, the area ratio was also 0.21% or less, and the tensile strength of the lead member 33 after the endurance test was larger than 35N.

Example 3

Embodiment of the said ceramic heater is described using FIG.

In order to reduce the average pore diameter and porosity of the ceramic core material 36 and the ceramic sheet 34,

① Reduce particle size of raw material,

② Increase the pressurized volume density of the raw material,

③ Formulate the particles to finely fill the raw materials,

It is good to take the means.

When the raw material particle diameter is made small, filling during molding becomes difficult, and the plastic shrinkage rate of the ceramic core material 36 becomes larger than that of the ceramic sheet 34, and the ceramic core material 36 is greatly reduced. In this case, if the ceramic core 36 is temporarily fired first, shrinks in advance in a predetermined ratio, and then the ceramic sheet 34 is wound on the surface of the ceramic core 36, the plastic shrinkage can be adjusted. have.

In addition, in order to raise the pressurized volume density of a raw material, it is preferable to process a raw material in the shape near a spherical shape. When the raw material is an angular shape, the powder blocks each other and blocks the filling when pressurized, so that the powder filling rate at the time of molding does not increase. For this reason, the pores in a ceramic will increase. For this reason, when the raw material is processed into a spherical shape at the time of manufacturing the raw material, or the raw material is crushed by a ball mill or the like to remove the angled parts, the pressurized volume density of the powder can be increased to reduce the porosity. The fine raw material produced by this grinding | pulverization is effective also in the particle size mix for fine-filling a raw material. Here, the pressurized volume density is a density when the powder is filled into a mold and molded under constant pressure.

If the average porosity is less than 1 µm, when the cation is concentrated on the cathode side 38b due to the migration, the volume of pores that absorb the cation is small, causing a problem that the ceramic heating element 3 is broken and disconnected. On the contrary, when larger than 10 micrometers, it turned out that the density of the anode side 38a becomes excessively loose, and the problem that durability deteriorates rapidly arises.

In addition, when the porosity of the ceramic core material 36 is A and the porosity of the ceramic sheet 34 is B, when the A / B is less than 0.3 and greater than 0.95, the durability becomes about 1/2. there was.

In addition, since the porosity A and B are 1-10% of each being stable in manufacture, it is preferable.

In the cation transfer due to migration, the ceramic core material 36 on the inner side of the heat generating resistor 2 is larger than the ceramic sheet 34. Therefore, by reducing the porosity of the ceramic core material 36, the density on the anode side is prevented from being extremely poor and durability is improved.

Here, the evaluation method regarding an average porosity and a porosity is demonstrated.

First, the ceramic heater 7 is filled with resin, cross sectioned, and 1000 times the photograph is taken with a metal microscope. Subsequently, the image processing apparatus (device name: LUZEX-FS manufactured by Nireco Co., Ltd.) provided the number of pores of 1 µm or more in the range of 1 viewing field = 240 µm x 160 µm in each of the ceramic core 36 and the ceramic sheet 34. By measuring the diameter, the average pore diameter, the porosity A of the ceramic core material 36, and the porosity B of the ceramic sheet 34 are measured, and A / B is calculated.

Next, the measuring method of durability is demonstrated. The voltage was applied so that the highest heating part of the ceramic heater 7 which is an evaluation sample might be 1200 degreeC, and the average time until both the quantity and sample which disconnected after 200 hours reached the disconnection was measured. The diameter of the pores used here was 0.1 micrometer or more.

It can be said from Table 3 that the average pore diameter of the pores is 1 to 10 µm. If the average pore diameter is 1 µm or less, when the cation is concentrated on the cathode side 38b due to the migration, the ceramic heating element 3 is broken and disconnected because the volume of pores into which the cation enters is small. On the contrary, it was found that at 10 µm or more, the anode side 38a was excessively poor, resulting in a problem of rapidly deteriorating durability.

Table 4 shows that in the relationship A / B in which the porosity of the ceramic core 36 is A and the porosity of the ceramic sheet 34 is B, the durability of the ceramic heater is improved when 0.3 ≦ A / B ≦ 0.95.

Example 4

Embodiment of the said ceramic heater is described using FIG.

The ceramic heater 7 of the present invention is a ceramic heater formed by integrally firing a ceramic sheet 34 formed by forming the heat generating resistor 2 on one main surface, and sintering the main surface to the ceramic core member 36 integrally. In (7), for example, in the developed view of the heat generating resistor 2 shown in FIG. 16, the average of the line widths of the center portion 40a of the heat generating resistor 2 is Ps, and the average of the line widths of both ends 40b. When it is set to Po, it is characterized by Ps <Po.

For example, as shown in Fig. 16, the average Po and Pn of the line width can be divided into two in the center and four in both sides when the number of the linear portions reciprocated by the heat generating resistor 2 is six. By dividing it evenly, it is good to calculate each average.

By setting the average Ps of the line widths of the center portion 40a of the heat generating resistor 2 to be the average Po of the line widths of the outer portion 40b, the resistance value of the line of the center portion 40a becomes higher than the resistance value of the outer line, thereby providing the center portion 40a. The temperature of can be made higher than the outside.

As a result, the temperature of the ceramic heater 7 can be increased quickly.

In particular, when the line width of the outermost pattern is widened, the heat generating portion in the circumferential direction is narrowed, so that it is possible to locally heat the ceramic heater 7, and that the local heating portion is brought close to the inner wall of the oxygen sensor to It is possible to improve the temperature raising performance.

In general, the oxygen sensor for detecting theoretical air-fuel ratio, which is widely used, detects the oxygen concentration when a part of the detecting unit of the oxygen sensor is heated above the operating temperature, so that the operating performance of the oxygen sensor can be improved by the present invention. do.

In recent years, the oxygen sensor has good low temperature operability, and when heated to 300 ° C or higher, the oxygen sensor starts to operate.

Further, the line width of the pattern in the center portion 40a of the heat generating resistor 2 of the ceramic heater 7 of the present invention is set to P1 toward the groove portion 41 of the outer side 40b in order to P2, P3, ... When the position is given by Pn, the line width P is adjusted so that P1 < P2 &lt; At this time, the line width P1 is preferably set to 50% to 95% of the line width Pn. Moreover, Preferably, it is preferable to set it as 50%-80%.

The ratio of the line width P to the above range is that when the line width P1 of the center portion 40a of the heat generating resistor 2 exceeds 95% of the line width Pn of the outer side 40b, the ceramic heater 7 Since the temperature distribution of the surface becomes small, it takes time to raise the temperature, and it is delayed to raise the oxygen sensor 43, which is the object to be heated, to the operating temperature.

On the contrary, when the line width P1 is less than 50% of the line width Pn, heat generation is concentrated in the center portion 40a of the heat generating resistor 2, so that cracks are likely to occur in the center portion 40a. On the other hand, when the line width P1 is set to 50 to 95% of the line width Pn, the oxygen sensor 43, which is a heating element, can be heated up to an operating temperature quickly, and cracks generated on the surface of the ceramic heater 7 can be prevented. You can prevent it.

As shown in Fig. 15, there is also a method of locally heating the heat generating portion by increasing the angle C at which the pattern of the heat generating resistor 2 is not formed. In that case, the angle C is set to 60 ° or more, or the line width Pn at both ends of the heat generating resistor 2 is increased by 10% or more with respect to the average Po of the line width at the center portion to suppress heat generation at both ends thereof. It is also possible to promote heat generation and make local heating easier.

In addition, when the line width Pn at both ends of the heat generating resistor 2 is made larger than the average line width Po of the center portion 40a to suppress heat generation at both ends, it is preferable to promote the localized heating by making the heat generating area smaller than the apparent angle C. It becomes possible.

As shown in FIG. 17, the pattern end surface of the heat generating resistor 2 can be arranged with respect to the groove portion 41 as a reference, for example, within a range of 90 ° to 270 °. The design of forming the temperature distribution on the basis of the groove portion 41 is that when the ceramic heater 7 is set to the oxygen sensor 43, the maximum temperature portion m of the ceramic heater 7 is set to the oxygen sensor 43. ) To improve thermal efficiency. In order to judge the maximum temperature part m from an external appearance, it is also possible to design so that the maximum temperature part m may exist in the position of 180 degrees with respect to the groove part 41 as a reference.

As shown in FIG. 18, the oxygen sensor 43 can be operated efficiently by bringing the maximum temperature portion m of the ceramic heater 7 of the present invention into contact with or in proximity to a part of the inner circumferential surface of the oxygen sensor 43. It becomes possible. At this time, the highest temperature portion (m) of the heat generating resistor 2 is installed to approach the inner peripheral surface side of the oxygen sensor 43. At this time, the interval g between the ceramic heater 7 and the inner wall 43a of the oxygen sensor 43 is preferably 0.5 mm or less, and preferably 200 μm or less.

The oxygen sensor 43 operates at 350 to 400 ° C. In addition, it is not necessary to heat the whole oxygen sensor 43, and it operates if it can heat a part of oxygen sensor 43 to this temperature range. Therefore, as shown in FIG. 18, the heat generated by the ceramic heater 7 is efficiently heated by bringing the heat generating portion 44 side of the ceramic heater 7 closer to the inner wall 43a of the oxygen sensor 43. It is possible to transfer to the oxygen sensor 43 by. With the same power consumption, it is possible to shorten the heating time by 10 to 20%.

By adjusting the line width P of the heat generating resistor 2 in this way, a part of the circumferential direction of the ceramic heater 7 can be locally generated to shorten the heating time of the oxygen sensor 43.

Examples of the ceramic heater are shown below. A ceramic sheet 34 having aluminum oxide as its main component and having a silicon oxide, calcium oxide, magnesium oxide, and zirconium oxide adjusted to be within 10% by weight in total is prepared, and a heat generating resistor composed of W-Re or the like on this surface (2) ) And the electrode lead-out portion 5 made of W and the like. Moreover, the electrode pad 9 was printed on the back surface.

The heat generating resistor 2 has a 4 reciprocating pattern with a heat generation length f of 5 mm, and the pattern width P becomes wider as the pattern width P of the central portion 40a is narrowed to the outside 40b. Made to lose. And it adjusted so that the pattern width P of the center part 40a with respect to the pattern width P of the outer side 40b might be 60 to 100%. In addition, the resistance value of the heat generating resistor 2 was adjusted so that it might be 2.4Ω. Then, a through hole 35 is formed at the end of the electrode lead-out portion 5 made of W or the like, and conduction of the electrode pad 9 and the electrode lead-out portion 5 is achieved by injecting paste therein. The ceramic sheet 34 thus prepared was brought into close contact with the periphery of the ceramic core member 36 and fired at 1500 to 1600 ° C. to obtain the ceramic heater 7.

Ten samples having different design specifications of the pattern width P are produced, these samples are set on the surface of the oxygen sensor 43, and as shown in FIG. 18, the thermocouple 45 is set on the surface thereof. The time until the temperature of reached 300 degreeC was evaluated.

Furthermore, these samples were given initial power which reached 1100 degreeC for 1 minute, and the ON and OFF cycle with room temperature was performed. The number of cycles at which the change rate of resistance becomes 110% or more of the initial resistance value is recorded in Table 5.

As shown in Table 5, Nos. 2 to 11 in which the relationship between the line widths P1 and P2 of the center portion 40a of the heat generating resistor 2 and the average Po of the line widths of both ends P3 to P6 are Ps> Po are given. Both showed favorable temperature rising characteristics.

In addition, it was confirmed that the arrival time of the surface temperature of the heated object becomes shorter as the difference in the pattern width P becomes larger toward the outer side 40b. From the viewpoint of durability of the ceramic heater 7, it was confirmed that the samples 1 to 6 and the samples 8 and 9 were effective.

From these results, it was confirmed that the pattern adjustments in the ranges of Samples 2 to 6 and Samples 8 and 9 are effective in thermal shock to the ceramic heater 7 and thermal efficiency to the heated object.

In addition, as shown in Table 6, in order to efficiently transfer heat to the oxygen sensor 43, the distance g between the ceramic heater 7 and the inner wall 43a of the oxygen sensor 43 is 0.5 mm or less, more preferably. It was confirmed that it is preferable to set it as 200 micrometers or less.

In the same manner as in Example C, 15 ° to 345 °, 45 ° to 315 °, and 90 ° for checking the length f of the heat generating resistor 2 in the circumferential direction with respect to the groove part 41 as a reference. The sample was produced so that the heat generating resistor 2 might be arrange | positioned in the range of -270 degrees, 135 degrees-225 degrees, and 150 degrees-210 degrees. As described above, the thermocouple 45 was set on the surface of the oxygen sensor 43 to evaluate the attainment temperature up to 300 ° C.

As can be seen from the results, it was confirmed that the time to reach the target temperature of the surface of the heated object can be shortened by arranging the heat generation pattern locally.

Example 5

Embodiment which used the said ceramic heater for the glow plug is demonstrated based on drawing. 20-23 shows the example which applied the ceramic heater 7 of this invention to the glow plug used for a diesel engine with its internal structure. The ceramic heater 7 is formed of a ceramic heating element 3 in which a heating resistor 2 made of an inorganic conductive material is embedded in a silicon nitride sintered body.

The ceramic heater 7 is formed with a two-stage cylindrical structure consisting of a small-diameter cylindrical portion 8 for joining the ceramic heating element 3, a tapered structure portion 10 serving as a sealing surface, and a large diameter cylindrical portion continuous to the tapered structure portion. By soldering one cylindrical member 6, the electrode lead portions 5a and 5b of the heating resistor 2 embedded in the ceramic heating element 3 are led out as electrode terminals.

This structure makes it possible to make the design specifications of the cylindrical member 6 unnecessary to change and to improve the compatibility only by easy design changes of the inner peripheral surface 19 and the open end surface 20 of the attachment member 22. It became.

On the other hand, on the rear end side 4 of the ceramic heating element 3, the electrode extraction member 22 is solder-bonded at the same time as the cylindrical member 6.

On the outer circumferential surface of the large cylindrical portion 11 of the cylindrical member 6, a fitting portion 31 having a stepped portion 12 and axially reduced toward the open end 13 is formed, and the cylindrical member ( 6) and the attachment member 18 are press-fit into the fitting portion 31 and the attachment member 18 of the cylindrical member 6 on the inner circumferential surface, and the stepped portion 12 is attached to the attachment member 18. A terminal having a flange 25 inserted into the insulator 24 through a conductive buffer 23 such as a washer to the electrode extracting member 22 by being brought into contact with the open end surface 20 of The rod 26 is inserted into and connected, and the rear end circumference 29 of the attachment member 18 is fixed by caulking at the end surface 30 of the insulator 24 and the rear end side 4 of the ceramic heating element 3. The electrode extracting member 22 and the terminal rod 26 soldered and bonded to each other are similarly press-bonded to form a positive electrode, and the terminal rod 26 is made of bakelite or the like. The negative electrode of the by fixing the insulating washer 27 with a nut 28 attached to member 18 and the plus electrode of the terminal rod 26 be isolated consists of a ceramic glow plug (21).

The conductive buffer 23 is preferably made of a material having a specific resistance of 10 ⁻² Ωcm or less and Brinell hardness of 100 or less, for example, in order to lower the contact resistance.

In addition, the terminal rod 26 is inserted into the insulator 24 to caulk the trailing edge 29 of the attachment member 18 at the end face 30 of the insulator 24, thereby ensuring electrical insulation.

The insulator 24 into which the terminal bar 26 is inserted may be made of insulating glass having a compressive strength of 5 MPa or more, for example, aluminum oxide glass, so as to withstand caulking of the trailing edge 29 of the attachment member 18. Resin glass etc. are used preferably.

In addition, the fixing can be made more secure by fixing between the terminal rod 26 and the insulator 24 with an adhesive, for example, an anaerobic adhesive.

In the ceramic heater of the present invention, as the heat generating resistor 2 made of the inorganic conductive material, other than high melting point metals such as tungsten (W), molybdenum (Mo), and rhenium (Re), for example, tungsten carbide (WC) ), Titanium nitride (TiN), molybdenum silicide (MoSi ₂ ), zirconium boride (ZrB ₂ ), and the like. Group 4a, Group 5a, Group 6a carbides or nitrides are also preferably used.

Next, the Example of the said glow plug was evaluated in detail below.

First, a ceramic powder obtained by adding a sintering aid such as an oxide of a rare earth element to a silicon nitride powder is molded into a flat molded body by a known press molding method or the like, and screen printing is performed on the molded body by using a paste containing tungsten carbide (WC) as a main component. By the method, the heat generating resistor 2 is formed in a U-shaped pattern, and similarly the electrode lead-out portion is formed to the side surface of the molded body.

Next, a lead pin was mounted so as to electrically connect the heat generating resistor 2 and the electrode lead-out part 5, and the other molded body was stacked thereon, and then a ceramic heating element having a cross-sectional square shape was obtained by a hot press firing method. (Above, city omitted)

Next, as shown in FIGS. 20-23, the said cross-sectional square ceramic heating body was rounded so that outer diameter might be 2.9 mm, and the ceramic heating body 3 was produced.

Then, the cylindrical member 6 and the electrode extracting members 5a and 5b were solder-bonded to the ceramic heating element 3 at the same time to produce the ceramic heater 7 of the present invention.

The attachment member 18 and the like were press-fitted and assembled in the ceramic heater 7 thus obtained under the same conditions as described above to produce a glow plug 21 shown in FIG. 20.

In addition, using the ceramic heating element 3 for comparison, the glow plugs shown in FIGS. 24 and 25 (Comparative Example A) and 26 and 27 (Comparative Example B) having the same outer dimensions as the glow plug 21 are used. Made.

As shown in FIG. 28, evaluation of the said each sample is made to apply the cantilever strength to the lid | cover body K in the form more practical to the taper structure part 10 of the attachment member 18 and the cylindrical member 6 initially. It fixed, and the cantilever strength was evaluated by applying the load N of 127N.

Next, the temperature rising characteristics were measured at a temperature evaluation position T of 2 mm from the front end of the ceramic heating element 3 at a temperature of 3.5 seconds after the applied voltage 11V.

The airtightness measured the gas leak R by adding the gas pressure P of 4 Mpa for 15 second from the ceramic heat generating body 3 side by the airtight leakage test prescribed | regulated to JIS-D5103.

The coaxiality of the ceramic heating element 3 was measured with a projector based on the attachment member 18.

The cracks of the heat generating resistor 2 and the ceramic heat generating body 3 were examined by X-ray permeation inspection.

The above results are shown in Table 8.

As can be seen from Table 8, in the cantilever strength and the temperature rising characteristic, the effect of the structure being different from the conventional product was concerned, but Comparative Examples A and B and Examples A and B of the present invention are cylindrical members 6. Irrespective of the outer diameter of the) and the attachment member 22, the equivalent was confirmed. In addition, no cracks were observed in the ceramic heating element in the X-ray fluoroscopy. In addition, it was confirmed that the product of the present invention was also very small in eccentricity (coaxiality) with the attachment member of the ceramic heating element. Moreover, also in airtightness, it was confirmed that this invention is very favorable.

The ceramic heater according to the present invention can be used for automobile air-fuel ratio detection sensor heating heaters, vaporizer heaters, soldering iron heaters, oxygen sensor heaters, glow plug heaters, and the like.

Claims (4)

A ceramic heater in which a heating resistor is incorporated in the ceramic heating element, and a lead member is attached to the ceramic heating element so as to conduct electricity with the heating resistor and the lead member, wherein the amount of Si in the lead member is 0.05% by weight or less. Ceramic heater. The ceramic heater according to claim 1, which is used for an oxygen sensor or a glow plug. A ceramic heater in which a heating resistor is embedded in the ceramic heating element, an electrode pad for energizing the heating resistor is provided on the surface of the ceramic heating element, a plating layer is formed on the surface of the electrode pad, and a lead member is attached through a solder material. A method of fabricating a method comprising: forming an electrode pad on a ceramic heating element incorporating a heat generating resistor, forming a plating layer on the surface of the electrode pad, and increasing a water vapor partial pressure in a low temperature region, and in a high temperature region. A method of manufacturing a ceramic heater, comprising joining a lead member through a solder material by a heat treatment having a second heat treatment step in which the water vapor partial pressure is reduced. The method of claim 3, wherein the first heat treatment step is performed at a temperature of 200 ° C. or more and less than 600 ° C., a water vapor partial pressure of 900 ° C. or more and 2400 kPa or less, and the second heat treatment step is performed at a temperature of 600 ° C. or more and less than 1000 ° C. and a steam partial pressure of 900 kPa or less. Method for producing a ceramic heater, characterized in that.

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