JPH11343180A - Ceramic-member/metallic-member joined body and ceramic heater using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joined body in which any cracks are not caused in a ceramic member and any peeling of a metallic member is not caused, even when the joined body is affected by a thermal history of heating/cooling during operation using the body, and also to provide a ceramic heater which consists of the joined body formed by joining a metal fitting for an electrode to a ceramic heating element and is capable of maintaining high joining strength without causing abnormal heat generation or disconnection due to the change in resistance of a heating resistor, and also, excellent in thermal shock resistance and high temp. stability, and further, has good rapid heating-up characteristics and is appropriate for high temp. use. SOLUTION: This joined body 1 is formed by joining a ceramic member 2 to a metallic member 3 through a metallic layer 4 which has a 20 to 200 μm thickness (7) and into which the component 6 of the metallic member 3 is diffused to a <=10 μm depth from an interface 5 between the metallic member 3 and the metallic layer 4, in such a way that only the surface side 8 of the metallic member 3, which is abutted on the ceramic member 2, is bonded to the metallic layer 4. The ceramic heater 9 is formed by joining a ceramic heating element 10 consisting of an insulator 14 and a heating resistor made of an electrically conductive material, to a metal fitting 11 for an electrode through a similar metallic layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined body of various oxide-based or non-oxide-based ceramic members and metal members and a ceramic heater, and to various industrial machines including various sensors and measuring instruments. Equipment or various combustion equipment parts typified by ceramic heaters used for heating and ignition, internal combustion engine parts such as glow plugs, or semiconductor elements and resistors such as power transistors and diodes that generate heat when energized The present invention is applied to a joined body of a ceramic member and a metal member requiring heat resistance, such as an electronic component typified by a heat dissipation board on which the power element is mounted.

[0002] In particular, the ignition of various types of internal combustion engines such as large diesel engines for ships or power generation is promoted, including the promotion of starting of direct-injection diesel engines for automobiles with the aim of improving fuel efficiency, output, and exhaust gas. The present invention relates to a high-temperature ceramic heater suitable for a glow plug used for auxiliary or a heater for auxiliary heating such as an early activation type oxygen sensor for improving the exhaust gas.

[0003]

2. Description of the Related Art In addition to oxide-based ceramics conventionally used as insulating bases for various electronic components, in recent years,
Non-oxide ceramics with outstanding characteristics of high strength and low specific gravity, excellent in heat resistance, corrosion resistance, abrasion resistance and electric insulation, are used for various industrial machinery including chemical plants and machine tool parts. Also, it has been widely used as an internal combustion engine component such as a diesel engine for an automobile.

For example, when starting or idling a diesel engine, a glow plug for an internal combustion engine used for rapidly preheating the sub-combustion chamber, or an oxygen concentration in exhaust gas of the internal combustion engine is detected to control exhaust gas. Various auxiliary heaters, such as heaters installed to promote the activation of the oxygen sensor element, perform the conventional rapid temperature rise characteristics and durability such as wear resistance, heat resistance, and corrosion resistance. Instead of a sheath heater in which the inferior heating resistance wire and heat-resistant insulating powder are buried in a heat-resistant metal cylinder, a high-melting-point metal and its compound, and their main components, are converted into an electrically insulating ceramic sintered body with good thermal conductivity. 2. Description of the Related Art Ceramic heating elements which are integrated by supporting, joining, or burying heating resistors made of various inorganic conductive materials as components have been widely used.

However, since the ceramic is a brittle material, it is difficult to apply it to a portion to which repeated stress is applied. In addition, since the workability is poor, only the portion exposed to a high temperature has heat resistance, corrosion resistance, and resistance to heat. Various parts such as lightweight ceramics with excellent abrasion properties, metal parts with high strength and excellent workability are used for parts where high loads are applied, and ceramic and metal members are combined to form a composite structure. A joined body of ceramic and metal has been proposed.

[0006] For joining such a ceramic member and a metal member, conventionally, molybdenum (M
It has been widely adopted that a metal layer mainly composed of a high melting point metal such as o) is applied and a metal member is brazed and joined with a brazing material such as silver brazing through the metal layer.

However, in the joined body of the ceramic member and the metal member formed by the brazing, since the coefficients of thermal expansion of the two members are greatly different from each other, the distortion due to the difference in the thermal expansion, that is, the residual stress, is reduced. In the vicinity of the joint, for example, the glow plug for the internal combustion engine, and various auxiliary heaters, the joint between the electrode extraction portion of the ceramic heating element and the electrode fitting, particularly at the joint interface, is formed between the ceramic member and the metal member. However, there are disadvantages that the bonding strength is easily reduced, the ceramic member or the metal member itself is broken due to the contraction force of the metal member, and separation from the bonding interface is easily caused.

Therefore, in order to eliminate the difference in thermal expansion between the ceramic member and the metal member and maintain the bonding strength up to a high temperature,
As shown in FIG. 4, between the ceramic member 20 and the metal member 21, one or more of gold (Au), silver (Ag), copper (Cu), and nickel (Ni) are used as main components, and titanium (Ti) and vanadium are used. A number of so-called brazings, in which the metal layer 22 containing an active metal such as (V) is melted by heat treatment and joined, have been proposed (JP-A-6-321648, JP-A-7-25674, JP-A-7-272
No. 832).

[0009]

The joined body of the ceramic member 20 and the metal member 21 joined by melting and joining the metal layer 22 containing the active metal by heat treatment using the metal layer 22 containing the active metal as a brazing material,
In a thermal cycle test in which the initial strength and, for example, a normal temperature and a temperature of 450 ° C. were alternately exposed and repeated, the bonding strength between the ceramic member 20 and the metal member 21 was satisfactory even at about 3000 cycles.

[0010] However, for example, a ceramic heater incorporated in the sensor used for a recent internal combustion engine has a wide area which can be quickly activated by rapid temperature rise and can cope with a lean burn engine in accordance with stricter exhaust gas regulations. The temperature near the metal fittings of the ceramic heater reaches 500 ° C., which is higher than the conventional temperature of about 450 ° C., due to the rise in heat generation temperature. However, there is a problem that the joined body that is melted and joined cannot endure the condition corresponding to traveling 100,000 miles.

In other words, the repetition of the high-temperature condition and the rapid temperature increase as described above causes the meniscus formed by bonding the metal layer 22 to the contact surfaces 33 and 34 between the metal member 21 and the ceramic member 20. There is a problem that a minute crack 24 occurs in the ceramic member 20 along the portion 23.

As shown in FIG. 5, a ceramic heating element 26 composed of a heating resistor (not shown) made of an inorganic material and a ceramic sintered body 25 has a lead wire 27 connected to the heating resistor. In the ceramic heater 30 in which the electrode fitting 29 is melt-bonded via the metal layer 22 at the exposed part of the electrode connection part 28 electrically connected, the heating and cooling for a long time under the high temperature condition as described above. By repetition, a minute crack 24 is generated in the ceramic heating element 26 along the meniscus portion 23 formed by the metal layer 22 adhered to the contact surface side 33 and the side surface 34 of the electrode fitting 29 with the ceramic heating element 26, and the crack is generated. 24 further progresses during operation, and as a result, the electrode fitting 29 peels off from the ceramic heating element 26 while adhering a part of the ceramic sintered body 25, By or resulting resistance change in the resistive element damage, causing abnormal heat generation at the electrode portion reduces the life of the heater when energized, there is a problem that eventually results in disconnection.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the temperature of a joint between a ceramic member and a metal member during operation, for example, by rapidly increasing the temperature to as high as 500 ° C. Even when subjected to the heat history of heating and cooling for a long time, the ceramic member does not crack or the metal member does not peel off from the ceramic member. It maintains high bonding strength for a long time without peeling off from the ceramic heating element while being adhered, abnormal heat generation due to resistance change of the heating resistor of the ceramic heating element, and disconnection. Excellent impact resistance, high temperature stability,
An object of the present invention is to provide a joined body of a ceramic member and a metal member and a ceramic heater which have an excellent rapid temperature rising characteristic and are optimal for high temperatures.

[0014]

As a result of various studies on the above-mentioned problems, the present inventor has found that a conventional joined body of a ceramic member and a metal member has a problem in melting and joining a metal layer containing the active metal as a brazing material. Due to the thermal history, a slight residual stress is generated in the ceramic member corresponding to the periphery of the metal member. In addition, when the metal member is melted and joined, the ceramic layer 22 shown in FIG. 4 and FIG. As a result of the surface analysis of elements by X-ray microanalysis (EPMA) described in an overlapped manner, the metal member component 31 and the electrode fitting component 32 diffuse into the metal layer 22 and change their compositions. It was found that the hardness increased and the residual stress increased.

Further, around the joint with the metal member 21,
From the contact surface side 33 with the ceramic member 20, the metal member 21
Over the side surface 34, the corners of the metal member 21 elute and form an arc shape, and the melt-bonded metal layer 22 forms a meniscus portion 23, and stress concentrates around the joint. As a result, it was also found that the crack 24 was generated.

Therefore, the temperature rise at the time of joining the ceramic member and the metal member is suppressed to prevent the diffusion of the metal member component into the metal layer, and to suppress the increase in the hardness of the metal member. Even if the meniscus portion is removed, or the meniscus portion or the mountain-like swell is formed around the joint portion of the metal member, the metal member is not formed on the contact surface side with the ceramic member. By adhering only to the metal layer and not to the side surface of the metal member, it has been found that the reduction and concentration of the residual stress at that portion can be avoided, and the above problem can be solved.

That is, the joined body of the ceramic member and the metal member of the present invention contains a metal member component in which an intervening metal layer having a thickness of 20 to 200 μm is diffused only within a depth of 10 μm from the interface with the metal member. The metal member is bonded to the metal layer only on the contact surface side with the ceramic member, and the metal layer is not bonded on the side surface of the metal member.

Particularly, the ceramic member is a silicon nitride sintered body, or the metal layer is made of gold (Au).
And nickel (Ni) as a main component or containing at least one of vanadium (V) and molybdenum (Mo).

Further, in the ceramic heater according to the present invention, the metal layer interposed between the electrode fitting and the ceramic heating element has a thickness of 20 to 20 mm.
The metal layer has a thickness of 200 μm, and the metal layer contains an electrode fitting component diffused only within a depth of 10 μm from the interface with the electrode fitting, and the electrode fitting has a metal layer only on the contact surface side with the ceramic heating element. And the side surface of the electrode fitting is not bonded to the metal layer.

In particular, the ceramic sintered body constituting the ceramic heating element is a silicon nitride based sintered body;
Alternatively, the metal layer is made of gold (Au) and nickel (N
It is more preferable that i) be the main component or that at least one of vanadium (V) and molybdenum (Mo) be contained.

[0021]

According to the joined body of the ceramic member and the metal member and the ceramic heater of the present invention, the metal layer interposed between the ceramic member and the metal member has a thickness of 20 to 200 μm and a depth of 10 μm from the interface with the metal member. Only within this range, the metal member component is not diffused and contained, and the metal member is adhered only at the contact surface side between the metal layer and the ceramic member, and the metal layer is attached to the side surface of the metal member. Since there is no adhesion, the composition change of the metal layer is small, so that the hardness does not increase and the residual stress is suppressed, and the stress is concentrated on the ceramic member corresponding to the periphery of the joint of the metal member. Even if the heat history of repeated heating and cooling is extended, cracks may occur in the ceramic member around the joint with the metal member, and the metal member may peel from the ceramic member for a long period of time. This will be resolved.

In the case of the ceramic heater, the ceramic heating element, the electrode fitting and the metal layer have the same structure as that of the above-mentioned joined body, so that a crack is generated in the ceramic heating element and the electrode fitting becomes the ceramic sintered body. It maintains high bonding strength for a long period of time without peeling with a part adhered, abnormal heating due to resistance change of the heating resistor, or disconnection, as well as thermal shock resistance and high temperature stability. It is excellent, has rapid temperature rising characteristics, and can dramatically improve durability.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a joined body of a ceramic member and a metal member and a ceramic heater according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an enlarged view of a main part of a joined body of a ceramic member and a metal member according to the present invention, in which the results of the surface analysis of the metal member components diffused into the metal layer by X-ray microanalysis (EPMA) are shown. FIG.

In FIG. 1, reference numeral 1 denotes a joined body of a ceramic member and a metal member in which a ceramic member 2 and a metal member 3 are joined via a metal layer 4, and the metal layer 4 extends deep from an interface 5 with the metal member 3. It has a thickness 7 of 20 to 200 μm containing a metal member component 6 diffused only within 10 μm, and the metal member 3 is bonded only on the contact surface side 8 between the metal layer 4 and the ceramic member 2. The side surface 13 of the metal member 3 is one to which the metal layer 4 is not bonded.

In the present invention, the material applicable as the ceramic member is alumina (Al ₂ O ₃ ) or mullite (3Al ₂ O ₃ .2SiO ₂ ) for oxide ceramics.
₂ ), and non-oxide ceramics include silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), sialon, and aluminum nitride (AlN).

In particular, although the coefficients of thermal expansion of the metal member and the metal layer are different, in order to improve the durability in the high temperature atmosphere as described above, ytterbium is used as a matrix component instead of alumina (Al ₂ O ₃ ). A silicon nitride sintered body containing a rare earth element such as (Yb) or yttrium (Y) in the form of monosilicate and / or disilicate is optimal from the viewpoint of strength, fracture toughness and heat resistance.

The metal member to be joined to the ceramic member may be a metal having a coefficient of thermal expansion of about 3.0 to 7.5 × 10 ⁻⁶ / ° C., which is close to the coefficient of thermal expansion of the ceramic member. Molybdenum (Mo) and tungsten (W)
And low thermal expansion metals such as Fe-Ni based Invar alloys,
Alternatively, an Fe-P based Elinvar alloy, WC-TiC
-Co-based cemented carbide, etc., oxidation resistance and workability,
From the viewpoints of cost and cost, an Fe-Ni-Co alloy or an Fe-Ni alloy is desirable.

Further, in view of the ease of plastic deformation of the metal member, the metal member has a Young's modulus of 14 to 15 × 1.
0 ³ kg / mm ² to as an Fe-Ni-Co alloy show or Fe-
Fe-based alloys such as Ni alloys are optimal, and furthermore, the thickness of the metal member can be reduced from the viewpoint that the stress generated due to the difference in thermal expansion between the two members due to the plastic deformation of the metal member itself can be absorbed. Needless to say, it is more preferable that the corners of the metal member be chamfered or rounded in order to avoid stress concentration as is well known. .

On the other hand, as a metal layer for joining the ceramic member and the metal member, the main component is gold (Au) or nickel (Ni), copper (Cu), silver (Ag), or palladium (Pd). At least 400 ° C
The metal layer is made of gold (Au) when there is no deterioration due to oxidation even when used at the above high temperature.
Is optimally an alloy of gold (Au) and nickel (Ni) in which 50 to 99% by weight and nickel (Ni) is 1 to 50% by weight.

In the metal layer, titanium (Ti), vanadium (V), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), which is a group 4a element of the periodic table, is used as an active metal. ), Molybdenum (Mo), silicon (Si), zirconium (Zr), hafnium (H
It is preferable to contain any one or more of f).

In particular, vanadium (V) or molybdenum (M) is used from the viewpoint that the metal layer has good wettability to the ceramic member and does not deteriorate the strength of the ceramic member.
It is optimal to contain at least one of o) as an active metal, and such an active metal may be contained in the form of a nitride, carbide, hydride or the like.

When the content of the active metal is less than 1% by weight, the effect of improving the bonding strength is not seen, and when it exceeds 10% by weight, the baking temperature of the metal layer becomes high, and a large residual stress occurs during cooling. 1 to 10% by weight is preferable, and particularly 1 to 5% by weight is optimal, since it is likely to cause cracks.

Accordingly, as the metal layer made of the noble metal containing the active metal, specifically, gold (Au) and / or
Or the total amount of silver (Ag) and one or more of nickel (Ni) or palladium (Pd), or one of copper (Cu) or cobalt (Co) and silicon (Si) is 90 to 99% by weight, Vanadium (V), molybdenum (Mo), titanium (Ti), zirconium (Zr), hafnium (Hf), manganese (M
and n) those containing any one or more active metals.

In the present invention, the hardness of the metal layer is remarkably increased when the metal layer component is eluted and diffused into the metal layer beyond the depth of 10 μm from the interface with the metal member during bonding. Since it increases and the residual stress increases in that portion, causing cracks, it is necessary to control the diffusion range of the metal member component to be within 10 μm.

Therefore, when the thickness of the metal layer is less than 20 μm, the capacity of the metal layer becomes insufficient, and the bonding strength such as nests becomes insufficient and the bonding strength becomes insufficient. When the thickness exceeds 200 μm, the capacity of the metal layer becomes excessive and the residual stress increases, and cracks occur in the ceramic member in a short time, resulting in a decrease in strength. Will be.

For this purpose, the thickness of the metal layer is 20 to
The thickness is specified to be 200 μm, and 20 to 150 μm is preferable in consideration of workability in forming a metal layer.

Next, in the present invention, in order to avoid concentration of stress on the ceramic member around the joint of the metal member, the side surface of the metal member is bonded to the metal layer in the form of bonding between the metal member and the metal layer. It is most preferable that the metal layer does not form a meniscus portion. Even if the metal layer forms a meniscus portion or a mountain-like swell, it is sufficient that the metal layer does not adhere to the outer peripheral side surface of the metal member. .

Accordingly, the joining method, the joining temperature, and the like are set so that the metal layer does not adhere to the outer peripheral side surface of the metal member, and the metal layer adheres only to the contact surface side with the ceramic member.
Control bonding conditions such as bonding pressure, or remove unnecessary parts by laser trimming or grinding, or apply a heat-resistant release agent such as BN to the outer peripheral surface of the metal member in advance and melt. It is necessary to join, etc. Among them, as a simple method, for example, in the case of an ultrasonic joining method in which static vibration is applied to join, a large melting or unnecessary portion is removed, or the mold is released in advance. The purpose can be achieved without applying an agent, which is convenient.

It is needless to say that the metal member and the metal layer need not be bonded to the entire surface as long as the required strength can be secured. It is desirable that the outer peripheral portion of the metal member and the outer peripheral portion of the metal layer be joined so as not to overlap any edge.

Next, FIG. 2 is an external view showing an example of the ceramic heater of the present invention, and FIG. 3 is an enlarged cross-sectional view of a main part of the ceramic heater of the present invention. FIG. 9 is a cross-sectional view in which the results of surface analysis of electrode fitting components diffused into a metal layer by the method are overlapped.

2 and 3, reference numeral 9 denotes a ceramic heater in which a ceramic heating element 10 and an electrode fitting 11 are joined via a metal layer 4. The ceramic heating element 10 is a heating resistor (not shown) made of an inorganic conductive material. ) And an insulator 14 made of a ceramic sintered body, and a lead wire 15 made of tungsten (W) or the like connected to the heating resistor is electrically connected to an electrode lead-out portion 16.
The electrode fitting 11 to which the i-lead pin 17 is spot-welded is electrically connected via the metal layer 4 to the ceramic heater 9.
Are formed.

In the present invention, the electrode fitting 11 is, for example, an ultrasonic wave while pressing both sides of the electrode fitting 11 substantially perpendicularly to the contact surface with the ceramic heating element 10 avoiding the spot welded Ni lead pin 17. By performing the bonding, the molten metal layer can be bonded to the side surface 13 of the electrode fitting 11 without bonding.

In this case, a gap 18 is formed between the electrode fitting 11 and the metal layer 4 by avoiding the Ni lead pin 17, and the electrode fitting component 12 diffuses into the metal layer 4. Of the metal layer 4 regardless of the thickness of the metal layer 4.
This is the simplest joining method since there is hardly any increase in the hardness due to the change in the composition and no increase in the stress is observed.

As the electrode fitting 11, any of the metal members described in detail above can be similarly used. Further, a soft metal wire such as a Ni wire is connected as the lead pin 17 by spot welding or the like and used as a ceramic heater. Under operating conditions in which vibration is applied, the physical load such as transmission of the vibration directly to the joint is reduced, so that problems such as separation of the joint can be further avoided.

When the ceramic heater is applied to a glow plug of an internal combustion engine or the like, the ceramic heater is operated by a DC power supply, and therefore, from the viewpoint of preventing a short circuit due to migration, the ceramic heater is used as the metal layer. Most preferably, the main component is gold (Au) and contains vanadium (V) or titanium (Ti) as an active metal.

The heating resistor made of an inorganic conductive material constituting the ceramic heating element of the present invention is made of a refractory metal such as tungsten (W), molybdenum (Mo), titanium (Ti), or tungsten carbide (WC). , Molybdenum silicide (MoSi ₂ ), titanium nitride (TiN), and other high-melting point metals such as carbides, silicides, and nitrides as main components. A material containing WC or W as a main component is preferred from the viewpoint of a difference in thermal expansion and a difficulty in reacting with them even at a high temperature.

It goes without saying that the constituents of the inorganic conductive material forming the heating resistor may be added to the insulating nitride ceramic sintered body to adjust the thermal expansion difference and reactivity.

On the other hand, with respect to the main component of the inorganic conductive material,
In order to prevent the crack due to the thermal expansion difference with the insulator by controlling the growth and not to increase the resistance,
Silicon nitride (Si ₃ N ₄ ), boron nitride (B
N), aluminum nitride (AlN) or silicon carbide (SiC), and the content thereof may be, for example, silicon nitride (S
i ₃ N ₄ ) is 5 to 30 parts by weight, and boron nitride (BN) is 1 to 30 parts by weight.
20 parts by weight, 1 to 15 parts by weight of aluminum nitride (AlN) and 3 to 15 parts by weight of silicon carbide (SiC) are preferable.

On the other hand, the heat generating resistor may be in a block shape, a linear shape, or a layer shape, and may be bent in a U shape, wound in a coil shape, or zigzag in a plane with the insulator interposed therebetween. When the heating resistor is bent and viewed in a plan view, the heating resistor has an arbitrary shape such as a U-shape or a W-shape. The heating resistor can be supported on an insulator, joined, or buried. For example, a laminated structure of two or more layers via an insulator may be applied, and a lead material made of a W material or the like may be electrically connected to both ends.

[0051]

Next, the present invention was evaluated as described in detail below. First, a ceramic raw material powder obtained by adding a sintering aid composed of an oxide of a rare earth element such as ytterbium (Yb) or yttrium (Y) to a silicon nitride (Si ₃ N ₄ ) powder, and an alumina (Al ₂ O ₃ ) powder Silica (SiO
₂ ) A ceramic raw material powder to which calcia (CaO) is added, and a raw material powder obtained by adding erbium oxide (Er ₂ O ₃ ) to aluminum nitride (AlN) as a sintering aid are formed into a flat plate by a known press molding method or the like. A heat-generating part is formed in a U-shaped pattern by a screen printing method using a paste mainly composed of WC on the surface on one end side of the molded body, and the other end of the ceramic molded body is similarly formed. An electrode portion is formed from the side to the side surface.

Next, a lead wire is placed so as to electrically connect the heating portion and the electrode portion, another ceramic molded body is placed thereon, and then, under a reducing atmosphere, 1700 to 190
A ceramic heating element was produced by firing and integrating at a temperature of 0 ° C.

Thereafter, the ceramic heating element was processed into a cylindrical shape by grinding, and transferred to the exposed electrode portion by a screen printing method or the like using a paste containing a metal layer component shown in Table 1, and then heated to 800 to 1300 ° C. A metal layer having a width of 3 mm and a length of 4 mm was formed by applying a baking process in a vacuum atmosphere.

The thus obtained ceramic heating element is provided with a 2 mm wide × 3 mm long × 0.2 mm thick Fe—Ni—C
After the electrode fittings in which the Ni lead pins were previously connected to the o-alloy by spot welding were joined by various joining methods shown in Table 1, a part including the joints of the electrode fittings was cut using a part of the ceramic heater for evaluation. The cross section was observed with a scanning electron microscope, and the thickness of the metal layer was measured.

Further, in the above-mentioned cross section, the ratio of the length of the metal layer actually joined to the length of the surface of the electrode fitting in contact with the ceramic heating element was obtained as a joining area (%) and evaluated.

Next, an X-ray microanalysis (EPM)
The surface analysis of the electrode fitting component diffused in the metal layer in A) is performed,
The depth of the metal layer containing the electrode fitting component from the interface of the electrode fitting was measured.

[0057]

[Table 1]

[0058]

[Table 2]

On the other hand, for the other ceramic heaters for evaluation, the joining strength of the electrode fittings, the bending strength of the ceramic heater including the joining parts of the electrode fittings, and the resistance change rate after the cooling / heating cycle test were measured. After the test, the ceramic heater was cut at a portion including the joint of the electrode fittings, and the cross section was observed.

The bonding strength is determined by fixing the ceramic heater for evaluation and measuring the N of the electrode fitting bonded to the ceramic heating element.
The i-lead pin was pulled in a direction perpendicular to the ceramic heating element, and the load (kgf) when the joint, the Ni lead pin or the electrode fitting was broken was measured and evaluated together with the breaking mode.

The bending strength was evaluated by performing a cantilever bending test by holding the ceramic heater for evaluation and pressing the joint of the electrode fittings.

Further, in the cooling / heating cycle test, the exposure of the ceramic heater for evaluation to the room temperature and the atmosphere of 500 ° C. was repeated as one cycle, and the resistance value of the ceramic heater after 3000 cycles was measured. The resistance change rate with respect to the initial resistance value was determined, and the ceramic heater after the test was cut along a cross section including the electrode fittings to observe the presence or absence of cracks.

[0063]

[Table 3]

As is clear from the table, in Sample Nos. 1, 8, 11 and 15, which are outside the scope of the present invention, the bonding strength of the electrode fittings is 8 kgf or less, and Sample Nos. 10, 14, 17 , 18, 27, 28, and 30, although the bonding strength of the electrode fitting exceeded 8 kgf, the resistance change rate after the thermal cycle test was as large as 3.0 or more, and cracks were observed in the ceramic heating element. .

On the other hand, in the present invention, the joint strength of the electrode fittings exceeded 8 kgf, the rate of change in resistance after the thermal cycle test was as small as 2.6 or less, and no cracks were observed in the ceramic heating element. It can be seen that the stress concentration around the joint of the electrode fitting is effectively alleviated.

In the above embodiment, the ceramic heater has been described. However, the joining form of the present invention is not limited to the above embodiment, and may be of any type without departing from the gist of the present invention. The same effect can be obtained by applying the present invention to the joining of a metal piece such as an electrode to a metallized portion formed on the surface of a ceramic sintered body substrate on which a power transistor such as an IGBT is mounted.

[0067]

As described above, in the joined body of the ceramic member and the metal member of the present invention, the elution and diffusion of the metal member component into the metal layer is suppressed within 10 μm from the interface with the metal member, and the metal member is 20-200μ on the contact surface side with the ceramic member
Since the metal layer with a thickness of m is bonded and bonded, no stress increase occurs due to elution and diffusion of the metal component into the metal layer interposed between the two members, and the metal layer is bonded to the side surface of the metal member The stress concentration around the joint of the metal member is suppressed, and the physical stress at the time of joining is reduced, the increase in the stress of the metal layer itself is suppressed, and repeated exposure to room temperature and high temperature environment Also, cracks do not occur in the ceramic member,
An extremely reliable joined body of a ceramic member and a metal member and a ceramic heater which maintain high strength and do not cause deterioration of an electrical connection state can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part of an example showing a joined body of a ceramic member and a metal member according to the present invention, and is shown by X-ray microanalysis (E).
FIG. 9 is a cross-sectional view in which the results of surface analysis of metal component components diffused into the metal layer by PMA) are superimposed.

FIG. 2 is an external view showing an example of the ceramic heater of the present invention.

FIG. 3 is a cross-sectional view in which a cross-section of a main part of an example of the ceramic heater of the present invention is enlarged, and a result of a surface analysis of an electrode fitting component diffused in a metal layer by X-ray microanalysis (EPMA) is superimposed. .

FIG. 4 is a cross-sectional view in which a main part of a conventional joined body of a ceramic member and a metal member is enlarged, and a result of a surface analysis of a metal member component diffused into a metal layer by X-ray microanalysis (EPMA) is superimposed. is there.

FIG. 5 is a cross-sectional view in which a cross section of a main part of a conventional ceramic heater is enlarged, and a result of a surface analysis of an electrode fitting component diffused in a metal layer by X-ray microanalysis (EPMA) is superimposed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joined body of ceramic member and metal member 2 Ceramic member 3 Metal member 4 Metal layer 5 Interface 6 Metal member component 7 Thickness 8 Contact surface side 9 Ceramic heater 10 Ceramic heating element 11 Electrode fitting 12 Electrode fitting component

Claims (8)

[Claims] 1. A joined body of a ceramic member and a metal member joined via a metal layer having a thickness of 20 to 200 μm,
The metal member is bonded on the contact surface side between the metal layer and the ceramic member, and the metal layer is 10 μm from the interface with the metal member.
A joined body of a ceramic member and a metal member, comprising a metal member component diffused within m. 2. The joined body of a ceramic member and a metal member according to claim 1, wherein said ceramic member is a silicon nitride sintered body. 3. The joined body of a ceramic member and a metal member according to claim 1, wherein the metal layer contains gold (Au) and nickel (Ni) as main components. . 4. The bonding between a ceramic member and a metal member according to claim 1, wherein the metal layer contains at least one of vanadium (V) and molybdenum (Mo). body. 5. A ceramic heating element comprising a heating resistor made of an inorganic conductive material and a ceramic sintered body and an electrode fitting having a thickness of 20 mm.
A ceramic heater joined through a metal layer of about 200 μm, wherein the electrode fitting is adhered on the contact surface side between the metal layer and the ceramic heating element, and the metal layer is within 10 μm from the interface with the electrode fitting. A ceramic heater comprising an electrode fitting component diffused into a ceramic heater. 6. The ceramic heater according to claim 5, wherein the ceramic sintered body constituting the ceramic heating element is a silicon nitride sintered body. 7. The ceramic heater according to claim 5, wherein said metal layer contains gold (Au) and nickel (Ni) as main components. 8. The ceramic heater according to claim 5, wherein said metal layer contains at least one of vanadium (V) and molybdenum (Mo).