JP2000016878A - Bonded structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the mechanical properties and corrosion resistance of the bonded structure in an alumina-metal bonded body by increasing the strength and fracture toughness of the interfacial reactive layer and enhancing corrosion resistance and the like. SOLUTION: This is a bonded structure comprising the alumina part composed of single crystal alumina or polycrystal alumina (the first part) 1 and the metal part containing at least Cu and active metals, for example, Ag-Cu-Ti complex (the second part) 3. The reactive layer 2 of these bonding interface is formed on the inter face between the first reactive layer 4 containing an active metal as Ti and the alumina part and has the second reactive layer 7 substantially free from the active metal as Ti and containing Cu-Al-O.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure between a metal member and an alumina member such as single-crystal alumina or polycrystalline alumina.

[0002]

2. Description of the Related Art Alumina members such as single-crystal alumina and polycrystalline alumina are used in a wide range of applications from materials for electronic parts to materials for structures. For example, when an alumina member is applied to a material for an electronic component, it is essential to form a metal conductive layer on its surface, and when applied to a structural material, it is bonded to a metal material or another ceramic material. Therefore, a metal layer is formed on the surface.

An active metal brazing material such as Ag-Cu-Ti is used for metallizing the surface of the alumina member. Active metal brazing is one of the important methods for joining ceramic materials with metal materials and other ceramic materials because of its productivity and reliability. In this method, the brazing material containing an active element such as Ti wets the ceramic by a chemical reaction between the active element and the ceramic, which contributes to the improvement of the bonding characteristics. Since wetting of ceramics by liquid metal is a material phenomenon of interface formation, clarification of the interface structure and its formation process is important not only for industrial applications but also for basic research on metal-ceramics wetting. .

[0004] With respect to ceramic materials containing alumina, there is an increasing demand for miniaturization along with the progress of various technical fields, and as a result, it is important to control the interface at the nanometer scale and control the reaction process at the interface. Is coming. Therefore, nanoscopic analysis and control of the brazing interface is important for controlling the interface reaction and improving various properties of the bonding interface.

Various discussions have been made on the bonding interface between the active metal brazing material and the alumina member. Regarding the reaction phase at the bonding interface, Ti-O, Ti-Al, Ti-Cu, Ti-C
Various reaction products such as u-O have been reported. Also, as a result of nanoscopic TEM analysis of the bonding interface between alumina and the active metal brazing material, for example, TiO and T
It has been reported that a reaction product having a double layer structure such as i ₃ Cu ₃ O is present (Santella et al J. Am. Ce)
ram. Soc., 1990, 73, 1785).

As described above, the conventional Ag-Cu-Ti
In brazing using an active metal brazing material such as, at the bonding interface between the alumina member and the active metal brazing material, an interface reaction layer made of a reaction product containing Ti such as TiO or Ti ₃ Cu ₃ O is formed, Through this interface reaction layer, the bonding between the alumina member and the active metal brazing material is realized.

[0007]

However, the conventional interface reaction layer containing Ti has a drawback that it is brittle because it is a compound having ceramic properties. The brittleness of the interface reaction layer has a problem that the strength and the fracture toughness of the joint structure between the alumina member and the brazing metal are reduced.

Accordingly, in the conventional joint structure, the fracture toughness value does not exceed that of the alumina member as the base material, and further, the strength and toughness value of the joint body are reduced by the brittleness of the interface reaction layer. There was a drawback that it was lower than that. Further, when an alumina member is used for a corrosion-resistant member, for example, there is a problem that an interfacial reactant causes a reduction in corrosion resistance.

In view of the above, it is strongly desired to improve the strength, fracture toughness, corrosion resistance, etc. of the interface reaction layer in the joint structure between the alumina member and the metal member.

The present invention has been made to address such a problem, and by improving the strength, fracture toughness, and corrosion resistance of an interfacial reaction layer, the joint structure of an alumina member and a metal member can be improved. It is an object of the present invention to provide a joint structure capable of improving mechanical properties, corrosion resistance, and the like.

[0011]

Means for Solving the Problems A joint structure of the present invention comprises:
As described in claim 1, a joint comprising a first member mainly made of alumina, and a second member joined to the first member via an interface reaction layer and containing at least Cu and an active metal. In the structure, the interface reaction layer includes a first reaction layer containing the active metal and a second reaction layer mainly composed of Cu-Al-O generated on the interface side with the first member. It is characterized by having.

In the joint structure according to the present invention, for example, as described in claim 2, the first member is made of monocrystalline alumina or polycrystalline alumina, and the second member is made of a brazing material containing at least Cu. A complex with an active metal is used. Further, as the active metal, for example, it is preferable to use at least one selected from Ti, Zr and Hf as described in claim 3, and particularly to use Ti as described in claim 4.

[0013] In the joint structure of the present invention, the second member mainly composed of Cu-Al-O containing substantially no active metal is provided on the interface side with the first member made of single-crystal alumina or polycrystalline alumina. A reaction layer is being generated. Cu-Al-
The reaction layer mainly composed of O has metallic properties and is much softer than Ti ₃ Cu ₃ O or TiO which exhibits ceramic properties. Therefore, by forming such a reaction layer at the bonding interface, the strength and fracture toughness value of the alumina-metal bonded structure can be improved. That is, not only does the second reaction layer mainly composed of Cu—Al—O cause a destruction, but also the soft second reaction layer plays a role of a buffer material, so that the strength and destruction of the joint structure can be improved. The toughness value can be improved. Further, C
Since the second reaction layer mainly composed of u-Al-O has excellent corrosion resistance, it contributes to improvement of the corrosion resistance of the alumina-metal bonded structure.

[0014]

Embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view schematically showing the main structure of one embodiment of the joint structure of the present invention. In FIG. 1, reference numeral 1 denotes an alumina member (first member) made of single-crystal alumina or polycrystalline alumina. The alumina member 1 is a metal member containing at least Cu and an active metal (a first member) via an interface reaction layer 2. 2) 3 to form a joint structure 4.

The alumina member 1 is not particularly limited, and single-crystal alumina or polycrystalline alumina can be used as described above. A so-called sapphire substrate or the like can be used as single-crystal alumina, and an alumina sintered body or the like can be used as polycrystalline alumina. The shape of the alumina member 1 can be appropriately selected according to the intended use of the joint structure 4, and can be widely applied, for example, from a substrate shape to various structural material shapes.

The metal member (second member) 3 only needs to contain at least Cu and an active metal as a material composition before the bonding process. Ti, Zr, Hf as active metals
Etc. can be used, and it is particularly preferable to use Ti. Examples of such a metal member 3 include an active metal brazing material such as an Ag-Cu alloy containing an active metal or Cu containing an active metal as described above.

The active metal is preferably contained in the metal member 3 in the range of about 1 to 10% by weight. When the amount of the active metal is less than 1% by weight, the amount of a compound layer as a reaction layer, which will be described in detail later, is insufficient, and the bonding strength with the alumina member 1 cannot be sufficiently increased. On the other hand, if it exceeds 10% by weight, the amount of the compound layer may be excessively increased and the bonding strength may be reduced, or the reactivity may be reduced and the bonding strength may be deteriorated.

Among these, Ag-Cu-Ti alloys containing Ti as an active metal, Ag-Cu-Ti laminates and mixtures of Ag-Cu alloys and Ti, and Ag-Cu-Ti laminates and mixtures of Ag, Cu and Ti are particularly preferred. A Ti composite is preferably used. The Ag-Cu-Ti composite has a good function as both a brazing material layer and a metallized layer. In addition, since Ti as an active metal has excellent reactivity with the alumina member 1, the basic bonding strength between the alumina member 1 and the metal member 3 can be increased.

The alumina member 1 and the metal member 3 as described above are joined via the interface reaction layer 2. Here, the interface reaction layer 2 has the first reaction layer 4 containing the above-mentioned active metal as a main reaction layer. This first reaction layer 4
Is that the active metal present in the metal member 3 wets the surface of the alumina member 1 during the bonding process (heat treatment), and the active metal becomes a constituent element of the metal member 3 or a constituent element (Al , O).

The form of the first reaction layer 4 containing at least an active metal (such as Ti) is, for example, a double layer of a reaction layer 5 mainly composed of Ti—Cu—O and a reaction layer 6 mainly composed of Ti—O. Structure. These reaction layers 5 and 6 further contain a small amount of Al.
i ₃ (Cu, Al) consisting etc. ₃ O, and the reaction layer 6 is made of (Ti, Al) O and (Ti, Al) such as O _2.
The reaction layers 5 and 6 containing these active metals (Ti) vary depending on the bonding conditions and the like, and there may be a case where only the reaction layer 5 mainly composed of Ti—Cu—O is used.

The joining structure 4 of the present invention is mainly composed of Cu-Al-O generated on the interface side with the alumina member 1 separately from the first reaction layer 4 containing an active metal such as Ti described above. It has a second reaction layer 7. The second reaction layer 7 is an interfacial reaction layer that characterizes the present invention, and forms a second reaction layer 7 substantially free of such an active metal such as Ti on the interface side with the alumina member 1. This makes it possible to improve the mechanical properties, corrosion resistance, and the like of the alumina-metal joint structure 4.

That is, the second reaction layer 7 mainly composed of Cu—Al—O substantially not containing an active metal such as Ti has metallic properties, and exhibits a ceramic-like property.
It is much softer than i ₃ Cu ₃ O or TiO. By generating such a soft reaction layer 7 at the bonding interface, the strength and fracture toughness value of the alumina-metal bonded structure 4 can be improved. This is because there is no possibility that the second reaction layer 7 may cause a destruction, and the soft second reaction layer 7 plays a role of a cushioning material.
Can increase the strength and fracture toughness of the steel. Further, C
Since the second reaction layer 7 mainly composed of u-Al-O also has excellent corrosion resistance, it contributes to improving the corrosion resistance of the alumina-metal joint structure 4.

The second reaction layer 7 mainly composed of Cu—Al—O substantially free of an active metal such as Ti as described above does not necessarily have to be formed continuously at the bonding interface. Even if they are formed discontinuously as shown in FIG. 1, the effect is exhibited. Cu
The amount of the second reaction layer 7 mainly composed of —Al—O is not particularly limited, as long as the effect of improving the strength and fracture toughness of the joint structure 4 and the effect of improving the corrosion resistance can be obtained. It may be in a discontinuous state.

The above-described alumina-metal joint structure 4 can be manufactured, for example, as follows.
Hereinafter, a case where an Ag—Cu—Ti composite is used as the metal member 3 will be described as an example.

First, the alumina member 1 and the metal member 3 are laminated. At this time, the metal member 3 is made of Ag-
Cu-Ti alloy foil, laminate of Ag-Cu alloy foil and Ti foil, mixture of Ag-Cu alloy powder and Ti powder, Ag foil, C
laminate of u foil and Ti foil, Ag powder, Cu powder and Ti
Various forms such as a mixture of powders can be used. Ag-Cu preferably uses a eutectic composition or a composition in the vicinity thereof. When single-crystal alumina is used as the alumina member 1, the crystal planes constituting the bonding surface are not particularly limited, and include (0001) plane, (101 (bar) 0) plane,
Various crystal planes such as the (112 (bar) 0) plane can be used as the bonding plane.

In order to obtain the joint structure of the present invention,
As described above, only the laminate of the alumina member 1 and the metal member 3 may be used. However, when further joining other metal members or ceramic members, another member to be joined on the metal member 3 is required. Can be arranged.

The laminate of the alumina member 1 and the metal member 3 as described above is subjected to a heat treatment in a high vacuum atmosphere of, for example, 10 ^-5 Pa or less. The heat treatment may be performed with the laminate pressed, or may be performed without pressure.

The heat treatment temperature is at least equal to or higher than the eutectic temperature (1051K) of the Ag-Cu eutectic alloy.
It is preferable to be within the range. If the heat treatment temperature is lower than 1123K, the activity of Ti cannot be sufficiently increased, and C
A direct reaction between u and the alumina member 1 cannot be caused. On the other hand, if the heat treatment temperature exceeds 1273K,
Has an excessively high activity, which may lead to infiltration of Ti into the second reaction layer 7 and the like. Further, the heat treatment at the above-described temperature is preferably performed for a period of 100 seconds or more. If the heat treatment time is less than 100 seconds, a sufficient activation reaction by Ti cannot be obtained, and a direct reaction between Cu and the alumina member 1 cannot be caused.

As described above, the laminate of the alumina member 1 and the metal member 3 is placed in a high vacuum atmosphere in the
By performing a heat treatment at a temperature in the range of 273 K for 100 seconds or more, a direct reaction between Cu and the alumina member 1 occurs, and T
A second reaction layer 7 mainly composed of Cu—Al—O substantially not containing an active metal such as i can be formed on the interface side with the alumina member 1.

[0031]

Next, specific examples of the present invention will be described.

EXAMPLE First, a sapphire substrate having a purity of 99.99% (a single crystal of α-Al ₂ O ₃ ) was placed on a (0001) plane, a (101 (bar) 0) plane, a (112 (bar) 0) plane, or the like. Parallel to various low-index surfaces of
Polishing was performed using diamond abrasive grains having a particle size of 0.25 μm. The size of each substrate was 10 × 2 × 0.5 mm.

Each of the sapphire substrates described above was
Use two sapphire substrates with a thickness of 100
FIG. 2 with a μm Ag—Cu—Ti alloy sheet interposed.
As shown in (a), sapphire 11 / Ag-Cu-T
A laminate of i-alloy 12 / sapphire 11 was obtained. Ag-C
66.7wt% Ag-28.4wt% as u-Ti alloy sheet
An active metal brazing material having a Cu-4.9 wt% Ti composition was used.

The laminated body of sapphire 11 / Ag—Cu—Ti alloy 12 / sapphire 11 has a density of 5 × 10 ⁻⁵ Pa
In the following high vacuum atmosphere, the eutectic temperature (105
1K) and heat treatment at a temperature of 1173K or more.
A brazed joint 13 as shown in FIG. Heat treatment time is
The pressure was 300 seconds and no pressure was applied during brazing. In the heat treatment, the temperature was raised to 1173K at a rate of 5K / min,
After holding for 300 seconds, the furnace was cooled at a cooling rate of about 20 K / min.

As shown in FIG. 2 (b), the obtained brazed joint 13 is cut perpendicularly to the joining surface by a low-speed diamond saw (cut surface S), and a diamond abrasive having a maximum grain size of 0.25 μm is cut. The cut surface was mechanically polished using a polishing disk having grains. Next, in order to obtain electrical transparency, the sapphire 11 / Ag—Cu—Ti alloy 12 / sapphire 11 joint was formed into a shape as shown in FIG. 3 using a FIB (Focused Ion Beam) processing apparatus. processed.

In this case, one piece of the cut junction is mounted at right angles on a scanning ion microscope, and the Ga ⁺ ion F
The IB was scanned over the desired portion and the material was sputtered. Since the ion beam is directed through the thickness of the sample, the thickness uniformity of the alumina, braze metal and reaction phase is generally maintained. By controlling the FIB operation, the thickness of the bonding portion 14 can be reduced to 60 nm or less.

This is very important for nanometer-scale analysis. Since the difference in sputtering rate between sapphire and brazing metal is about 10 times (when using Ga ⁺ ions accelerated at 30 kV), this technique has a great effect on ceramic-metal composites.

FIG. 4 schematically shows a TEM observation image of the sample subjected to the above-described treatment. As shown in FIG.
Reaction layer 15 between u eutectic alloy 12 ′ and Al ₂ O ₃ 11
Is generated. Next, nanoprobe analysis of the reaction layer 15 was performed using FE-TEM. The minimum probe diameter was 0.5 nm.

FIG. 5 schematically shows a TEM observation image using a nanoprobe. In FIG. 5, the portion at point 5 is Al ₂
O ₃ , and points 1 to 4 correspond to the reaction layer 15. Each part (points 1 to 4) of the reaction layer 15 is a different kind of reaction layer (point 2).
And point 3). Reaction product of point 1 (1)
Has a polycrystalline structure formed from relatively large particles,
This grain boundary is very flat. This indicates that this layer has recrystallized. All particles were randomly oriented without showing a clear orientation relationship with Al ₂ O ₃ . This structure was observed on the surface of all sapphire substrates regardless of the plane direction of the substrate.

Reaction products (2) at points 2 and 3
Is a polycrystalline layer formed between Al ₂ O ₃ (5) and the reaction product (1), and the thickness of the layer is between 10 and 50 nm due to local variations in the shape and size of the particles. Was changing. This reaction product (2) did not show a clear orientation relationship with Al ₂ O ₃ (5) or the reaction product (1).

EDS / EELS analysis was performed to determine the chemical composition of the reaction products (1) and (2). The beam diameter is about 0.5 nm, which is small enough to analyze the nanostructured reaction interface. FIG. 6 shows a typical EDS spectrum. Reaction products (1) and (2) are Ti, C
It contains each atom of u and Al. Here, Ti was dominant in the reaction product (2). Further, in each of the reaction products (1) and (2), the presence of oxygen was confirmed by EELS.

From the results of the above composition analysis and the crystal structure analysis by electron diffraction, the reaction product (2) is TiO, and the reaction product (1) is a Ti—Cu—O composition, probably Ti ₃ Cu ₃ O It is. Since these two phases contain a small amount of Al, TiO (Al) and Ti ₃ (Cu, Al)
It is considered that ₃ O was formed. The reaction product at the point 3 is the same as the reaction product (2) at the point 2 except that the Al content is slightly higher.

FIG. 7 shows the EDS spectrum of the reaction product (4) at the point 4 portion. As is clear from FIG.
The portion at point 4 contains Cu, Al and O, but hardly any Ti. Although the crystal structure of the reaction product (4) composed of Cu-Al-O is not clear, it is clear that a reaction product substantially containing no Ti was present. It shows that it reacted directly. Such a multiple interface structure was generated regardless of the crystal plane of the sapphire substrate.

As described above, the interface reaction layer 15 is made of Ti ₃
It has a reaction layer containing Ti made of (Cu, Al) ₃ O or TiO (Al) and a reaction layer made of Cu—Al—O containing substantially no Ti. Among them, Cu-Al-
The reaction layer made of O is a characteristic reaction layer in the joint structure according to the present invention, and has a metallic property and has a ceramic property such as Ti ₃ (Cu, Al) ₃ O or TiO 2.
It is much softer than (Al). By forming such a soft reaction layer at the bonding interface, the strength and fracture toughness of the alumina-metal bonded structure can be improved, and it also contributes to the improvement of corrosion resistance.

It should be noted that Ti ₃ Cu _{3 having} a thickness of about 1 to 2 μm is used.
The O reaction layer is made of all sapphire 11 / Ag-Cu-Ti
Although always observed in alloy 12 joints, a thinner T
In some cases, the iO layer was not observed. T of irregular shape
The iO particles were present at intervals rather than in continuous layers.

[0046]

As described above, according to the present invention, the strength and destruction of the interface reaction layer of the alumina-metal bonded structure can be improved by the reaction layer mainly composed of Cu-Al-O containing substantially no active metal. The toughness value, and further, the corrosion resistance and the like can be increased. Therefore, it is possible to provide an alumina-metal bonded structure having improved mechanical properties and corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a main structure of a joint structure according to an embodiment of the present invention.

FIG. 2 is a view showing a process of manufacturing a joined body according to an embodiment of the present invention.

FIG. 3 is a diagram showing a processed shape of a sample when a TEM observation of a joined body is performed in an example of the present invention.

FIG. 4 is a diagram schematically showing a TEM observation result of a joined body according to an example of the present invention.

FIG. 5 is a diagram schematically showing a TEM observation result using a nanoprobe of a conjugate according to an example of the present invention.

FIG. 6 is a view showing an EDS spectrum of a first reaction layer portion of the joined body according to the embodiment of the present invention.

FIG. 7 is a diagram showing an EDS spectrum of a second reaction layer portion of the joined body according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Alumina member 2 ... Interface reaction layer 3 ... Metal member 4 ... First reaction layer 7 ... Second reaction layer

Claims (6)

[Claims] 1. A joint structure comprising: a first member mainly made of alumina; and a second member joined to the first member via an interface reaction layer and containing at least Cu and an active metal. The interface reaction layer includes a first reaction layer containing the active metal and Cu-Al generated on an interface side between the first reaction layer and the first member.
And a second reaction layer mainly composed of -O. 2. The joining structure according to claim 1, wherein the first member is made of single-crystal alumina or polycrystalline alumina, and the second member is a composite of a brazing material containing at least Cu and an active metal. A joint structure comprising a body. 3. The bonding structure according to claim 1, wherein the active metal is at least one selected from Ti, Zr, and Hf. 4. The joint structure according to claim 3, wherein the active metal is Ti. 5. The bonding structure according to claim 1, wherein the first reaction layer containing Ti is a reaction layer mainly composed of Ti—Cu—O generated on the interface side with the second member. A joining structure characterized by having. 6. The bonding structure according to claim 5, wherein the first reaction layer containing Ti further includes a reaction layer mainly composed of Ti—O generated on the interface side with the second reaction layer. A joining structure characterized by having.