JPH02248372A - Method for bonding members having different wettability with brazing material, its bonded body and its brazing material - Google Patents

Abstract

PURPOSE:To closely bond members having different wettability with a brazing material such as a ceramics and a metal by combining two sets of brazing materials having a different melting temp., arranging the mixture between the members and heating the materials. CONSTITUTION:The bonding of the members having different wettability with a brazing material is carried out as follows. Namely, a brazing material which is melted earlier and spread is arranged on the bonding surface of the member having worse wettability with the brazing material, a brazing material which is melted later and spread is arranged on the bonding surface of the member having better wettability with the brazing material, and the brazing materials are heated and melted to bond the members. When a ceramics (having worse wettability with the brazing material) and a metal (having better wettability with the brazing material) are bonded, for example, a brazing material (e.g. Ag-Cu-based one) contg. an active metal (Ti, Zr, etc.) is arranged on the ceramic a brazing material (e.g. Ag-Ca-based and Au-Cu-based ones) which is melted later than the brazing material contg. active metal is arranged on the metal, and the brazing materials are heated and melted in a nonoxidizing atmosphere to bond the ceramics and metal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to joining members having different wettability of brazing filler metal,
In particular, the present invention relates to a method for joining ceramics and metal, the joined body, and the brazing filler metal for joining.

[Conventional technology]

For joining members with different wettability of brazing filler metals, such as ceramics and metals, the surface of the ceramic can be bonded by using a so-called active metal-bearing brazing filler metal containing Cu, Ag, or Cu-Ag combined with Ti or Zr. It is known that it can be directly bonded to metal without pretreatment such as metallization (U.S. Pat. Nos. 2,739,375 and 4).
No. 471026).

Furthermore, after applying a paste of fine powder of silver solder containing active metals such as Ti and Zr to the surface of alumina ceramics and drying and fixing it, a foil-shaped soldering material formed from an ingot or Layering a foil-shaped brazing material containing less active metal than that applied to the surface of the alumina ceramics, and contacting the metal to be joined with this,
A method of brazing by heating in an inert atmosphere has been proposed (Japanese Patent Application Laid-Open No. 62-217533).
This is to allow the alumina ceramics and active metal to react well.

[Problem to be solved by the invention]

However, ceramics (
When directly bonding a material (a component that is difficult to wet with the brazing filler metal) and a metal (a component that is easy to get wet with the brazing filler metal), when the brazing filler metal begins to melt due to heating, the wettability of the metal is much better than that of the ceramic. At the same time, the active metal that should contribute to bonding with the ceramics spreads to metal parts other than the joint, causing the composition of the brazing material to change. There was a problem in that due to the change, normal joining could not be performed.

Furthermore, even if a brazing filler metal containing an active metal is placed on the ceramic side, if the melting point of the brazing filler metal placed on the metal side is low (the content of active metal is low), the brazing filler metal on the metal side that has eluted first may cause the brazing filler metal on the ceramic side to The brazing filler metal is melted and eroded, active metals are eluted, and the composition ratio of the brazing filler metal changes, inhibiting the so-called reaction with the ceramics.As a result, the brazing filler metal on the ceramic side wets and spreads to the metal side, resulting in complete failure. There was a problem that it could not be joined.

The above-described poor bonding is a serious drawback especially when bonding devices that require high airtightness.

The object of the present invention is to provide members having different wettability of brazing filler metals.

For example, it is an object of the present invention to provide a bonding method suitable for bonding ceramics and metals, particularly vacuum sealing bonding, a bonded body thereof, and a brazing filler metal for bonding.

[Means to solve the problem]

The gist of the present invention for achieving the above object is as follows.

In a method of joining parts with different wettability of brazing filler metal, the brazing filler metal is placed first on the joining surface of the part with poor wettability, and then the brazing filler metal is placed on the joining surface of the part with better wettability. The present invention relates to a method for joining members having different wettability of brazing materials, and a joined body, characterized in that a brazing material that melts and spreads later is placed on a surface, and the brazing material is heated and melted to join the members.

The present invention also provides a method for joining members having different brazing filler metal wettability, and the joined body, wherein the member having poor brazing filler metal wettability is a ceramic, and the brazing filler metal wettability is metal. .

In the above joining method, for example, when joining ceramics and metal, when the brazing material is heated, the brazing material placed in contact with the ceramic starts to melt. The molten brazing filler metal preferentially wets and spreads on the bonding surface of the ceramic and reacts with the ceramic.

Next, the brazing filler metal placed on the metal side melts and spreads over the bonding surface of the metal, and the brazing filler metal placed on the ceramic side melts and spreads over the metal bonding surface.
By cooling when the brazing filler metals placed on the sides have fused together, both brazing filler metals solidify and the ceramic and metal are firmly joined.

This prevents the brazing material placed on the ceramic side from spreading on the metal side and causing incomplete bonding, so that a good fillet is formed.

In the above, the brazing material placed on the ceramic side is
A g , Cu + N x * M n * A g
CuTNi-Cu, Cu-Mn,
Ag-Cu-Pd, Ag-Cu-I
n, Ag-Cu-Sn, at least one of Ti, Zr, and IIf, 0.5
It contains ~10% by weight.

In particular, in order to obtain a brazing material with a low melting point, a brazing material having a eutectic composition in which A g :Cu has a ratio of 72% by weight = 28% by weight is blended with 0.5 to 10% by weight of the active metal. desirable.

Furthermore, in order to lower the melting point,
One or more elements selected from the group can be blended. The blending amount is 5 to 30% by weight based on the brazing filler metal.
In particular, to improve wettability, I
It is preferable to mix n, Sn, Zn, etc.

In the above, the ratio of Ag:Cu:In is 50
~70% by weight: 15-30% by weight: By blending 0.5-10% by weight of Ti or Zr, it is possible to obtain a brazing material with a melting temperature of 800'C or less. can.

In contrast to the above, as a brazing material placed on the metal side.

When the active metal-containing brazing filler metal melts, it spreads over the joint surface of the metal, and the gold 3 prevents changes in the brazing filler metal composition. It is desirable that the value be higher than that. Such brazing materials include Ag-Cu, Au-Cu
, Pd-Ag-CurPd-Ag
etc.

The objects of the present invention can be achieved even if the two types of brazing filler metals are in the form of powder, paste, or foil.

Furthermore, the above two types of brazing fillers are composited, for example, clad, and a brazing filler metal layer containing an active metal is placed on the side in contact with the ceramic, and a brazing filler metal layer containing an active metal is placed on the side in contact with the metal. The objects of the present invention can also be achieved by using melting point brazing filler metal layers that are in contact with each other.

Furthermore, the two types of brazing filler metals may be configured to have a concentration gradient between their respective joint surfaces, and may be combined so that their melting temperatures have a temperature gradient.

By using the composite brazing filler metal as described above, the workability of joining can be improved.

As for the manufacturing method of the composite brazing filler metal, both brazing filler metals may be stacked and formed by rolling or the like. Alternatively, a paste-like brazing material may be laminated by printing or the like.

The ceramic materials of the present invention include AQ, 03°Mg
Oxide-based materials such as O, zrO, Si, N4. There are nitride-based materials such as AQN, and carbide-based materials such as SiC and WC.

This type of bonding between ceramics and metals is performed using Ar2 or N2.
It is preferable to carry out the process in a non-oxidizing atmosphere such as

However, the above-mentioned non-oxidizing atmosphere preferably does not contain oxygen, but it is acceptable as long as the oxygen content is at a level that does not adversely affect the bonding6.For example, if the oxygen content is on the order of several hundred ppm or less, it is acceptable. There are many.

Typical examples of such a bonded body include a valve such as a vacuum circuit breaker, or a general semiconductor device. It can also be applied to cordwood modules and micromodules.

Furthermore, it can be widely applied to industrial products that require such bonding.

[Effect]

In the present invention, bonding brazing filler metals with different wettability are arranged separately on the ceramic side and the metal side, and in particular, after the former brazing filler metal wets and spreads on the ceramic bonding surface, the latter brazing filler metal melts. By melting and spreading on the metal joint surface, the brazing filler metal on the metal side reacts after the bonding filler metal on the ceramic side acts effectively, so it does not wet and spread on the metal side. It can be thought of as having a uniform fillet formed at the joint.

In particular, in parts where the metal is Ni or is plated with Ni, even if active metals such as Ti, Zr, or Hf, which are highly reactive with Ni, are present in the brazing filler metal on the ceramic side, the The reason why the bonding can be performed without being affected is thought to be because the brazing filler metal placed on the metal side acts as a barrier while the brazing filler metal on the ceramic side wets and spreads.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 An example in which the present invention is applied to a valve of a vacuum circuit breaker will be described.

In this example, a cylindrical alumina ceramic l (outer diameter 75 mm x length 1
A Kovar cap 4 (maximum outer diameter 71 mm x 0) with Ni plating on the surface is attached to the end of the
．． 85 mm thick) were joined.

In the vacuum circuit breaker valve, a fixed electrode 9 is attached to a fixed holder 7, a bellows 8 and a movable electrode 10 are attached to a movable holder 18, and the cylindrical alumina ceramic 1 shields the valve from the outside air. ing.

On the cylindrical alumina ceramic 1 side end surface of the valve,
Ag-Cu-Ti-In (weight ratio: 62.3:
20.2 : 2.5 : 15) Foil-like (0
, 15 mm), and on the other hand, on the end surface side of the cap 4 made of Kovar, a foil (0.1 mm) made of a eutectic alloy of Ag-Cu (72:28 by weight) is arranged.
A brazing material 3 is placed and the two ends are butted.

Note that the melting point of the brazing filler metal 2 and the brazing filler metal 3 is 68
0°C, the latter 780°C.

The above was heated under a reduced pressure of 3 x 10-' Torr at a heating rate of 5.
The temperature was raised to 810°C at a rate of 0°C/min, held for 4 minutes, and then cooled to room temperature at a cooling rate of 50°C/min.

A schematic cross-sectional view of the joint between the Kovar cap 4 and the cylindrical alumina ceramic 1 of the above valve is shown in FIG.

After the active metal-containing brazing filler metal 2 reacts with the ceramic of the cylindrical alumina ceramic 1, the brazing filler metal 3 is melted, so that an extremely good fillet 5 is formed;
The cylindrical alumina ceramic 1 and the cap 4 were firmly joined by a joint 6.

In addition, the result of a leak test using IIs gas at the joint part of the joined body was 5 x 10-'' atm, CC 7 seconds or less, and a valve for a vacuum circuit breaker with extremely excellent airtightness was obtained.

Example 2 A Ni-plated mild steel tube was joined to an alumina ceramic tube for a magnetron in the same manner as in Example 1.

The amount of He gas leaked from the bonded body is 5×10-”atm,
The c c time was 7 seconds or less, and a highly airtight alumina ceramic bonded body for a magnetron was obtained.

Example 3 FIG. 3 shows a schematic vertical cross-sectional view of a semiconductor device of the present invention.

In the semiconductor device used in this embodiment, a semiconductor element 15 is mounted on an aluminum nitride substrate 11 for heat dissipation, and is connected to an external connection lead frame 16 with a bonding wire 17. The semiconductor element 15 is sealed with a Kovar cap 14 for protection.

In the above, between the aluminum nitride substrate 11 and the Kovar cap 14, Ag-Cu-In-Ti (weight ratio: 62:
25:10:2) A foil-shaped (0.1 mm) active metal-containing brazing filler metal 12 made of alloy is arranged, and a cap 13 made of Kovar is arranged.
A foil-shaped (0.05 mm) brazing filler metal made of an Ag-Cu (72:28 weight ratio) alloy with a melting point of about 780° C. was placed on the joint surface side.

This was heated to 810° C. in an Ar atmosphere of ITorr and then bonded in accordance with Example 1.

The amount of He leakage in the Ilo leakage test of the junction of the semiconductor device obtained by the above method was 5×10-”atm*
The c c time was 7 seconds or less, and a highly airtight semiconductor device was obtained.

Note that when a SiC ceramic substrate with high thermal conductivity and electrical insulation properties was used instead of aluminum nitride as the substrate 11, high airtightness was obtained similarly to the above.

Example 4 An alumina ceramic substrate 21 (
2mmtX50mmX50mm) Example 1
A foil-shaped (0.15 mm) active metal-containing brazing filler metal 22 made of the Ag-Cu-Ti-In alloy used in Example 1 was placed, and on top of it A foil-shaped (0.1 mm) brazing filler metal 23 was arranged. On top of that is a Kovar board 24 (1 mm x 10 mm
x 50 mm) were arranged in an inverted font shape.

This was heated and cooled under the same conditions as in Example 1.

FIG. 5 shows the cross-sectional shape of the joined body.

The brazing filler metal 22 reacted preferentially with the alumina ceramics due to the action of the brazing filler metal 23, wetted and spread to the alumina substrate side, and the brazing filler metal 23 was reacted and bonded to the Kovar plate 24.

This prevented the reaction between the brazing filler metal 22 and the Kovar plate 24, formed a good fillet 25, and produced a tight and strong joined body.

Example 5 Similar to Example 4, alumina ceramics substrate 21 (
2mmtX50mmX50mm) on the joint surface, Ag-C
A foil-shaped (0.1 mm) active metal-containing brazing material 22 made of u-Ti (71:27:2 by weight) alloy is arranged,
A foil-shaped (0.1 mm) brazing material 23 made of a eutectic alloy of A u Cu (weight ratio: 80:20) was placed thereon. Then, on top of that, a Kovar board 24 (1mm x
10 mm x 50 mm) were arranged in an inverted letterform.

This was heated to 900° C. under the same conditions as in Example 1, and then cooled.

As in Example 4, a good fillet 25 as shown in FIG. 5 was formed, and a tight and strong bonded body was obtained.

Example 6 An active metal-containing brazing filler metal (thickness 70 μm) made of Ag-Cu-In-Ti (63:22:12:3 by weight) alloy with a melting point of about 710°C and Ag with a melting point of about 780°C -Cu
(Weight ratio: 72:28) Brazing filler metals (thickness: 100 μm) made of eutectic alloy were overlapped and stretched under pressure at room temperature to produce a composite brazing filler metal (thickness: 100 μm).

The composite brazing material was able to tightly join ceramics and metal having the same structure as in Example 4. In addition, excellent workability was also obtained.

Example 7 Ag-Cu-In-Ti (62°3:20.2:15:2.5 by weight ratio) alloy powder log with a melting point of about 720°C
0.2 g of organic binder and ethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.), and diethylene glycol monoethyl ether acetate as a solvent for the binder.
1.8 g of the brazing filler metal was mixed and made into a paste, and applied to the surface of a polyethylene terephthalate film (thickness: 0.1 mm) to a thickness of about 100 μm using a doctor blade.

After drying the solvent at about 100°C, apply Ag-Cu having a melting point of 780°C (72:2 by weight).
8) Eutectic alloy powder was similarly applied to a thickness of 100 μm, and after drying, the film was peeled off to produce a composite brazing filler metal of approximately 200 μm.

The composite brazing material was able to tightly join ceramics and metal having the same structure as in Example 4, and also had excellent workability. Note that the binder could be removed by heating during the bonding.

Embodiment 8 FIG. 6 shows a schematic cross-sectional view of a cooling module for a large-sized computer according to the present invention.

A cooling fin 42 made of highly thermally conductive ceramics is bonded to the back side of the LSI 41 mounted on the ceramic substrate 11 with a solder layer 43.
is connected to a Kovar cap 44 having a bellows 45, and is connected to a cooling device 46 via the bellows 45. The cooling device is configured to circulate the coolant 47 to dissipate heat generated by the LSI.

In this example, the cooling fins 42 and the Kovar cap 43 were bonded together using a brazing filler metal in the same manner as in the semiconductor device of Example 3.

When a He leak test was conducted after bonding, the amount of I gas leaked was less than 5 x 10-''at, cc/sec, and the cooling module was able to be highly airtight.

【Effect of the invention〕

A brazing filler metal that melts and spreads first is placed on the joint surface of the component (ceramics) that has poor wettability.

By placing the brazing filler metal that later melts and spreads on the joint surface of the component (metal) side where the brazing filler metal has good wettability, it prevents excessive wetting and spreading of the filler metal at the latter joint, resulting in a uniform result. A fillet can be formed to tightly join both parts.

In particular, it provides extremely excellent bonding for parts such as ceramic substrates and metal caps of semiconductor devices that require airtightness, resulting in highly airtight devices. Figure 1 is a cross-sectional view of the vacuum breaker valve, Figure 2 is a schematic cross-sectional view of the joint between the Kovar cap of the vacuum breaker valve and cylindrical alumina ceramics, and Figure 3 is a cross-sectional view of the vacuum circuit breaker valve. Schematic diagram of a semiconductor device with a substrate and a metal cap,
4 and 5 are cross-sectional views showing the state before and after the ceramic plate and the metal plate are joined, and FIG. 6 is a schematic cross-sectional view of the cooling module for a large-sized computer according to the present invention.

1... Cylindrical alumina ceramics, 2, 12.22
...Active metal-containing brazing filler metal, 3,13.23...Metal brazing filler metal, 4,14.44...Kovar cap, 2
5...Fillet, 6,26...Joint part, 7...
Fixed holder, 8, 45... Bellows, 9... Fixed electrode, 10... Movable electrode, 11... Ceramic substrate, 15... Semiconductor element, 16... Lead frame,
17... Bonding wire, 18... Movable holder, 21... Alumina ceramic plate, 24... Kovar plate, 41... LSI, 42... Cooling fin, 43... Solder layer , 46... cooling device, 47...
・Refrigerant.

Figure 1 Figure 3...Metal brazing filler metal 4...Kovar cap...Aluminum nitride (AtN) Substrate...Active metal-containing brazing filler metal (62%Ag-25%Cu) -10%In-2%Ti...
- Brazing metal (72%Ag-28%CLI)... Kovar cap... Semiconductor element... Lead frame... Bonding wire 21... Alumina ceramics substrate 22... Active metal solder 23...・Metal solder 24... Kovar plate 25... Fillet 26... Joint part d]] 41...LSI 42...Cooling fin 44...Cap 45...Bead 46...・Cooling device 47... Refrigerant

Claims (1)

[Claims] 1. In a method for joining members having different wettability of brazing filler metals,
Place the brazing filler metal that melts and spreads first on the joint surface of the component side where the wettability of the filler metal is poor, and then place the brazing filler metal that melts and spreads later on the joint surface of the component side that has better wettability. A method for joining members having different wettability of brazing materials, characterized in that the brazing materials are joined by heating and melting. 2. In a method for joining members with different brazing filler metal wettability,
Heat is applied by creating a temperature gradient at the bonding interface so that the brazing filler metal wets and spreads first on the bonding surface of the component side with poor wettability, and then spreads on the bonding surface of the component side with good brazing filler metal wettability. A method for joining parts with different brazing filler metal wettability. 3. In a method for joining members with different brazing filler metal wettability,
Using a composite of brazing fillers with different melting temperatures, the brazing filler metal first wets and spreads on the joint surface of the component side with poor wettability, and later spreads on the joint surface of the component side with good wettability. A method for joining members having different wettability of brazing filler metals. 4. In the method for joining ceramics and metal, a brazing filler metal containing an active metal is placed on the ceramic side, a brazing filler metal that melts later than the brazing filler metal containing the active metal is placed on the metal side, and non-oxidizing. A method for joining members having different wettability of brazing filler metals, which is characterized by joining by heating and melting in a neutral atmosphere. 5. In the method for joining ceramics and metal, a brazing material layer containing an active metal is arranged on the ceramic side, and a brazing material layer having a higher melting point than the brazing material containing an active metal is arranged on the metal side. A method for joining members with different wettability of brazing materials, which uses a composite brazing material and is characterized by joining by heating in a non-oxidizing atmosphere. 6. Joining by the brazing filler metal that has melted and spread on the bonding surface of the component side where the brazing filler metal has poor wettability, and the brazing filler metal that has melted and spread on the bonding surface of the component side where the brazing filler metal has good wettability. A joined body of members having different wettability of brazing filler metal. 7. Ceramics characterized in that a brazing filler metal containing an active metal is bonded to the bonding surface on the ceramic side by a brazing filler metal having a higher melting point than the brazing filler metal containing the active metal and placed on the metal side. and metal joints. 8. In a semiconductor device including a semiconductor element mounted on a ceramic substrate, and the semiconductor element hermetically sealed by the ceramic substrate and a metal cap provided thereon, a brazing material containing an active metal is bonded to the ceramic substrate. 1. A semiconductor device, wherein a composite brazing filler metal having a melting point higher than that of the brazing filler metal is hermetically bonded to a bonding surface of a substrate by a composite brazing filler metal disposed on a bonding surface of the metal cap. 9. Joining of members with different wettability of brazing filler metals, characterized in that the brazing filler metal for joining members with different wettability of brazing filler metals is configured by laminating brazing filler metals with different wettability to one of the members. Brazing filler metal. 10. The brazing material on the ceramic side melts before the brazing material on the metal side, and the brazing material on the ceramic side is wetted before the brazing material on the metal side. Brazing filler metal for joining ceramics and metals. 11. A brazing material for joining ceramics or metals, characterized by comprising a laminate of a brazing material layer containing an active metal and a brazing material layer having a higher melting point than the brazing material.