JP2014161885A - Joining method of metal substrate and metal laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining a metal substrates efficiently by diffusive joining, and a metal laminate body to which a plurality of metal substrates are joined in a satisfactory state.SOLUTION: The joining method of metal substrates includes a process which laminates a first metal plating layer and a second metal plating layer which have the melting point of the temperature lower than the melting point of the metal substrate on at least a jointed surface of a plurality of metal substrates in the present order to form an insert layer and a process in which the metal substrate is heated and diffusive junction is applied between the insert layers, in a state where the insert layers of the joined surface is abutted and the metal substrates are piled up, and thus using the joining method of metal substrates a plurality of metal substrates are joined so as to compose a metal laminate body.

Description

  The present invention relates to a method for bonding a plurality of metal substrates and a metal laminate in which a plurality of metal substrates are bonded.

Conventionally, a three-dimensional shape or a hollow structure is formed by joining metal substrates on which desired processing has been performed.
For example, a laminate in which metal substrates with a plurality of micro holes are laminated and bonded so that the positions of the holes coincide with each other has a high aspect ratio of the micro holes. Is applied as a filter with good maintainability (Patent Documents 1 and 2).
In addition, a laminate in which a metal substrate having a fine groove formed on the surface is diffusion-bonded in a state where the groove is opposed so as to face the groove has a hollow structure as a microchannel, a microreactor, It is applied as a component such as a micro heat exchanger (Patent Document 3).
Furthermore, in the formation of a complicated hollow structure such as an ink jet head, a plurality of metal substrates having desired openings and the like are joined via an epoxy adhesive, or a specially shaped pressure jig Pressure bonding is performed at a high temperature in a state in which a plurality of metal substrates are pressed using a laser (Patent Documents 4 and 5).

JP 2000-109985 A JP 2011-147872 A Special table 2008-544862 gazette JP 2006-187784 A JP 2008-74072 A

In the above filter manufacturing, a method of directly joining metal substrates by solid phase diffusion bonding is adopted. For example, in solid phase diffusion bonding between stainless steel substrates, after being kept at high temperature and high pressure for a long time, In order to prevent the strength deterioration, there is a problem that gentle cooling is required and a long time is required for the joining process.
In addition, since the required pressure resistance is high in the production of a laminate having a hollow structure that functions as a microchannel, an unnecessary void is not generated between metal substrates when forming a three-dimensional channel. It is necessary to perform solid phase diffusion bonding. For this reason, the bonding process takes a long time under high temperature and high pressure, which is problematic in terms of productivity.
Furthermore, in the production of an ink jet head, it is possible to form a complicated hollow structure by partially dividing or joining with an epoxy adhesive, but it has high pressure resistance. There was a limit.
The present invention has been made in view of the above circumstances, and provides a method for efficiently bonding metal substrates by diffusion bonding, and a metal laminate in which a plurality of metal substrates are bonded in good condition. For the purpose.

  In order to solve such a problem, the metal substrate bonding method of the present invention includes a first metal plating layer and a second metal plating layer which are stacked in this order on at least the bonded surfaces of a plurality of metal substrates. And a step of diffusion bonding the insert layers by heating the metal substrates in a state in which the metal substrates are overlapped so that the insert layers on the surfaces to be bonded are brought into contact with each other. The melting point of the first metal plating layer and the melting point of the second metal plating layer constituting the insert layer are both lower than the melting point of the metal substrate.

As another aspect of the present invention, the constituent metal of the insert layer subjected to diffusion bonding is configured to diffuse into the metal substrate.
As another aspect of the present invention, the metal substrate is configured to be either a stainless steel substrate or a nickel substrate.
As another aspect of the present invention, the combination of the first metal plating layer / second metal plating layer constituting the insert layer is a gold plating layer / silver plating layer, a silver plating layer / gold plating layer, and a gold plating layer. / The electroless nickel plating layer is used.
As another aspect of the present invention, a gold plating layer that is the first metal plating layer is formed using a hydrochloric acid-based gold plating solution, and the thickness of the gold plating layer is in the range of 0.015 to 0.15 μm. The configuration is as follows.
As another aspect of the present invention, the first metal plating layer and the second metal plating layer constituting the insert layer are configured to be completely solid solution in the binary alloy phase diagram.
As another aspect of the present invention, the heating temperature for diffusion bonding the insert layers to each other is lower than the melting point of the melting point of the first metal plating layer and the melting point of the second metal plating layer constituting the insert layer. The configuration is set in the range of ± 100 ° C.

The metal laminate of the present invention is configured such that a plurality of metal substrates are bonded by any of the above-described metal substrate bonding methods.
As another aspect of the present invention, a metal substrate having three or more layers is provided, the metal substrate having at least two layers is provided with a processing portion, and at least a part of a region where the processing portion is located in each metal substrate is in a stacking direction. The configuration is inconsistent.

  In the metal substrate bonding method of the present invention, the insert layers located on the surfaces to be bonded of the metal substrate are diffusion bonded to each other. Therefore, the metal substrate is bonded at a relatively low temperature with the melting temperature of the insert layer being lower than the melting temperature of the metal substrate. In addition, the pressure required for diffusion bonding can be significantly reduced as compared with the case where metal substrates are diffusion bonded. Moreover, since the insert layer is directly plated on the metal substrate, desired pressure resistance performance and corrosion resistance performance can be obtained by performing diffusion bonding between the insert layers. As a result, the time required for bonding is greatly shortened, and the metal substrates can be bonded efficiently. Moreover, the metal laminated body of this invention has the several metal substrate joined in the favorable state, and has comprised the outstanding pressure | voltage resistance and corrosion resistance.

FIG. 1 is a process diagram for explaining one embodiment of a metal substrate bonding method of the present invention. FIG. 2 is a process diagram for explaining another embodiment of the metal substrate bonding method of the present invention. FIG. 3 is a partial cross-sectional view for explaining an embodiment of the metal laminate of the present invention.

Hereinafter, embodiments of the present invention will be described.
Note that the drawings are schematic or conceptual, and the dimensions of each member, the ratio of sizes between the members, etc. are not necessarily the same as the actual ones, and represent the same members. However, in some cases, the dimensions and ratios may be different depending on the drawing.

[Metal substrate bonding method]
FIG. 1 is a process diagram for explaining one embodiment of a metal substrate bonding method of the present invention.
In the present invention, the insert layer 3 is formed by laminating the first metal plating layer 4 and the second metal plating layer 5 in this order on the surface including the bonded surface 1 a of the metal substrate 1. Further, the first metal plating layer 14 and the second metal plating layer 15 are laminated in this order on the surface including the bonded surface 11a of the metal substrate 11 to form the insert layer 13 (FIG. 1A). Next, in a state in which the metal substrates 1 and 11 are overlapped so that the insert layers 3 and 13 of the surfaces to be joined 1a and 11a are brought into contact with each other, the metal substrates 1 and 11 are heated to diffusely bond the insert layers 3 and 13 to each other. (FIG. 1B).
As the metal substrates 1 and 11, stainless steel substrate, nickel substrate, nickel alloy substrate, chromium alloy substrate, titanium substrate, titanium alloy substrate, molybdenum alloy substrate, tungsten alloy substrate, niobium substrate, tantalum substrate, zirconium substrate, cobalt alloy substrate, etc. Can be used. Among these, examples of the material for the stainless steel substrate include austenitic, martensitic, and ferritic stainless steels. Examples of the material of the nickel substrate include nickel or nickel alloys such as permalloy, 42% nickel alloy, and invar. The materials of the metal substrates 1 and 11 are usually the same, but the materials of the metal substrates 1 and 11 may be different depending on the use after diffusion bonding. In addition, the metal substrates 1 and 11 may be preliminarily subjected to various fine processing such as grooves and holes by etching processing, press processing, or the like.

  Such metal substrates 1 and 11 may be subjected to pretreatment for the purpose of activation by degreasing the surface and removing the oxide film before forming the insert layers 3 and 13. As such pretreatment, for example, it can be appropriately selected from treatment methods such as alkali immersion treatment, alkaline electrolytic treatment, acid electrolytic treatment, and acid immersion treatment. When the metal substrates 1 and 11 are made of a material that easily generates an oxide film, the transition time from the pretreatment to the formation of the first metal plating layers 4 and 14 is such that the oxide film is formed on the metal substrates 1 and 11. The range is such that it is not reformed.

<Formation of insert layer>
Next, the formation of the insert layer will be described.
The melting points of the first metal plating layer 4 and the second metal plating layer 5 constituting the insert layer 3 and the melting points of the first metal plating layer 14 and the second metal plating layer 15 constituting the insert layer 13 are both metals. It is lower than the melting points of the substrates 1 and 11, and the difference between the melting points is preferably 90 ° C. or more. For example, when a stainless steel substrate or a nickel substrate having a melting point of about 1400 to 1500 ° C. is used as the metal substrates 1 and 11, the combination of the first metal plating layer / second metal plating layer is a gold plating layer / silver plating layer. Silver plating layer / gold plating layer, gold plating layer / electroless nickel plating layer (nickel phosphorus alloy layer) and the like.
Below, the formation method of the 1st metal plating layers 4 and 14 and the 2nd metal plating layers 5 and 15 is demonstrated.

When a gold plating layer is formed as the first metal plating layers 4 and 14, it is preferable to form the gold plating layer using a hydrochloric acid-based gold plating solution. The hydrochloric acid-based gold plating solution to be used is preferably one that takes into consideration the prevention of erosion of the metal substrates 1 and 11 and shortening of the plating time. For example, a hydrochloric acid-based gold plating solution prepared so that the degree of occurrence of micropitting corrosion on the surfaces of the target metal substrates 1 and 11 is 5 or less per unit area (mm ² ) can be used. Here, the micropitting corrosion is measured by immersing the metal substrate in a hydrochloric acid-based gold plating solution for 10 seconds, washing with water, and observing with a scanning electron microscope. By using such a hydrochloric acid-based gold plating solution, an appropriate corrosive action occurs on the surfaces of the metal substrates 1 and 11 as a simultaneous action during the gold plating, and the first metal plating layers (gold plating layers) 4, 14 And the metal substrates 1 and 11 have good adhesion.

The upper limit of the thickness of the gold plating layer as the first metal plating layers 4 and 14 to be formed is preferably 0.15 μm, and if it exceeds 0.15 μm, further improvement of the effect of the present invention is hardly obtained. This is not preferable because the material cost increases. The lower limit of the thickness of the gold plating layer to be formed is that uniform film thickness control is possible according to the plating solution used for forming the second metal plating layers 5 and 15, and the metal substrates 1 and 11. It is preferable to set it in consideration of the fact that it is possible to prevent corrosion, for example, 0.015 μm.
Moreover, when forming a silver plating layer as the 1st metal plating layers 4 and 14, a silver plating layer can be formed, for example using the acidic silver plating solution containing phosphines. By using an acidic silver plating solution containing phosphines, the formation of an oxide film on the surfaces of the metal substrates 1 and 11 is suppressed by the strong reduction action of phosphine, and the first metal plating layers (silver plating layers) 4 and 14 and the metal Adhesiveness with the substrates 1 and 11 is good. The acidic silver plating solution to be used is preferably one that takes into consideration the prevention of erosion of the metal substrates 1 and 11 and shortening of the plating time. For example, a silver plating solution prepared so that the degree of occurrence of micropitting corrosion on the surfaces of the target metal substrates 1 and 11 is 5 or less per unit area (mm ² ) can be used.

The upper limit of the thickness of the silver plating layer as the first metal plating layers 4 and 14 to be formed is preferably 0.5 μm, and if it exceeds 0.5 μm, the further improvement of the effect of the present invention is hardly obtained. This is not preferable because the material cost increases. The lower limit of the thickness of the silver plating layer to be formed is that uniform film thickness control is possible according to the plating solution used for forming the second metal plating layers 5 and 15, and the metal substrates 1 and 11. It is preferable to set it in consideration of the fact that it can prevent corrosion, for example, 0.1 μm.
On the other hand, when a gold plating layer is formed as the second metal plating layers 5 and 15, the plating solution used may be either a cyan gold plating solution or a hydrochloric acid gold plating solution. The cyan-based gold plating solution is not particularly limited, and a known plating solution can be used. The hydrochloric acid-based gold plating solution is not limited as in the case of forming a gold plating layer as the first metal plating layers 4 and 14, and a known plating solution can be used.
The thickness of the gold plating layer as the second metal plating layers 5 and 15 to be formed can be set as appropriate so that the insert layers 3 and 13 can be diffusion-bonded. It can be set to be a thin film of about 0.5 to 0.5 μm, preferably about 0.1 to 0.25 μm. If the thickness of the insert layers 3 and 13 exceeds 0.5 μm, further improvement in the effect of the present invention is hardly obtained, but the material cost increases, which is not preferable.

Moreover, when forming a silver plating layer as the 2nd metal plating layers 5 and 15, a well-known plating solution can be used. The thickness of the silver plating layer as the second metal plating layers 5 and 15 to be formed can be set as appropriate so that the insert layers 3 and 13 can be diffusion-bonded. The film thickness can be set to 1 to 0.5 μm, preferably about 0.15 to 0.3 μm. If the thickness of the insert layers 3 and 13 exceeds 0.5 μm, further improvement in the effect of the present invention is hardly obtained, but the material cost increases, which is not preferable.
Furthermore, when forming an electroless nickel plating layer as the second metal plating layers 5 and 15, an electroless nickel plating solution containing a phosphinate is used as a reducing agent, and phosphorus contained in the electroless nickel plating layer to be formed The amount is 10% by weight or more, preferably 10 to 13% by weight. When the phosphorus content in the electroless nickel plating layer is less than 10% by weight, the melting point of the electroless nickel plating layer (nickel phosphorus alloy layer) is high, and the diffusion bonding properties of the insert layers 3 and 13 are not preferable. . Moreover, the thickness of the electroless nickel plating layer as the second metal plating layers 5 and 15 to be formed can be appropriately set so that the insert layers 3 and 13 can be diffusion bonded. The thickness can be set to be a thin film having a thickness of 0.05 to 0.5 μm, preferably about 0.1 to 0.25 μm.

Here, the thicknesses of the first metal plating layers 4 and 14 and the second metal plating layers 5 and 15 constituting the insert layers 3 and 13 in the present invention are measured as follows. That is, after each metal plating layer is formed, measurement is performed using a fluorescent X-ray film thickness measuring device manufactured by Seiko Instruments Inc. In advance, prepare a thin standard foil and a thick standard foil that include the target film thickness value to be measured, and calibrate the X-ray output and film thickness using at least these two standard foils. To know the proportional relationship in advance. In addition, after performing cross-section processing with FIB (focused ion beam), the cross-section is observed with SEM (scanning electron microscope), and the metal particles appearing in the cross-section are measured based on the scale corresponding to the magnification to be photographed. The thickness is confirmed for each layer having a different size and crystal form.
In the illustrated example, the insert layers 3 and 13 are formed over the entire area of the metal substrates 1 and 11 including the bonded surfaces 1a and 11a. However, the insert layers 3 and 13 are formed only on the bonded surfaces 1a and 11a. May be. In this case, the plating layer can be formed such that only the surfaces to be joined 1a and 11a are in contact with the plating solution, and the portions where the formation of the insert layers 3 and 13 is not required are shielded with a mask, and the plating solution The plating layer may be formed so as not to contact the substrate.

<Diffusion bonding between insert layers>
Next, diffusion bonding between the insert layers will be described.
As described above, in the present invention, the metal substrates 1 and 11 are stacked so that the insert layer 3 on the bonded surface 1a of the metal substrate 1 and the insert layer 13 on the bonded surface 11a of the metal substrate 11 are brought into contact with each other. The insert layer 3 and the insert layer 13 are diffusion-bonded by heating in the combined state (FIG. 1B). The heating temperature in the diffusion bonding between the insert layer 3 and the insert layer 13 is any one of the melting points of the first metal plating layers 4 and 14 and the melting points of the second metal plating layers 5 and 15 constituting the insert layers 3 and 13. The lower melting point can be set within a range of ± 100 ° C., preferably ± 80 ° C. If the heating temperature setting is less than the lower limit of the above temperature range, solid phase diffusion bonding between the insert layer 3 and the insert layer 13 becomes insufficient, and voids are generated at the bonding interface, pressure resistance performance is lowered, and corrosion resistance is lowered. Etc. may occur, which is not preferable. Moreover, when heating temperature setting exceeds said temperature range, the spreading | diffusion to the metal substrate 1 side may advance and it is unpreferable because a non-uniform insert layer residue may be a concern.

  In FIG. 1B, the insert layer 3 and the insert layer 13 are respectively a laminate of the first metal plating layer 4 and the second metal plating layer 5, and the first metal plating layer 14 and the second metal plating layer 15. It is described that only the second metal plating layers 5 and 15 located on the bonded surface 1a and the bonded surface 11a are diffusion bonded, but this is described for convenience. Is. For example, in the diffusion bonding between the insert layer 3 and the insert layer 13, the first metal plating layer 4 and the second metal plating layer 5 are fused and integrated, and the first metal plating layer 14 and the second metal plating layer 15 Includes a state in which the insert layer 3 and the insert layer 13 are no longer laminated. In addition, in the diffusion bonding between the insert layer 3 and the insert layer 13, some of the constituent metals of the insert layers 3 and 13 may diffuse into the metal substrates 1 and 11, and this state is not excluded. The same applies to the following embodiments.

  In such a metal substrate bonding method of the present invention, the insert layers 3 and 13 located on the bonded surfaces 1a and 11a of the metal substrates 1 and 11 are diffusion bonded, so that the melting temperature of the metal substrates 1 and 11 is higher. Bonding can be performed at a relatively low temperature with the melting temperature of the low insert layers 3 and 13 as a guide, and the pressure required for diffusion bonding is greatly reduced compared to the case where the metal substrates 1 and 11 are diffusion bonded together. it can. Moreover, since the insert layers 3 and 13 are directly plated on the metal substrates 1 and 11, desired pressure resistance performance and corrosion resistance performance can be obtained by performing diffusion bonding between the insert layers. Therefore, the conventional process of holding at a high temperature and high pressure for a long time and the subsequent gentle cooling process for preventing the strength deterioration of the metal substrate are not required, and the time required for the bonding process can be greatly shortened.

<Diffusion into metal substrate>
In the present invention, the constituent metals of the insert layers 3 and 13 diffusion-bonded as described above may be diffused into the metal substrates 1 and 11 (FIG. 1C). Thereby, the intermetallic battery corrosion of a metal substrate and insert layer material can be avoided, and the metal laminated body which comprised the outstanding pressure | voltage resistant performance and corrosion resistance performance can be obtained. The diffusion of the constituent metals of the insert layers 3 and 13 into the metal substrates 1 and 11 can be performed by maintaining the heating in the diffusion bonding between the insert layers, and the heating temperature is set on the metal substrate. The temperature may be about 10 to 30% lower than the melting temperature.

  In this way, when the constituent metals of the insert layers 3 and 13 are diffused in the metal substrates 1 and 11, all combinations in the binary alloy phase diagram are combinations of the first metal plating layer / second metal plating layer that constitute the insert layer. A combination of metal plating layers that are solid solution is preferable. For example, a combination of gold plating layer / silver plating layer and silver plating layer / gold plating layer is preferable. In this way, as a combination of the first metal plating layer / second metal plating layer, a metal (insert layer) that diffuses in the metal substrates 1 and 11 by using a combination of metals that are completely dissolved in the binary alloy phase diagram. Of the metal substrates 1 and 11 after diffusion bonding is prevented, so that the composition of the metal) is stable, and only a specific metal constituting the insert layer is unevenly distributed on the surfaces of the metal substrates 1 and 11. Properties and physical properties are stable. In addition, as a combination of the first metal plating layer / second metal plating layer constituting the insert layer, a combination that is not completely solid solution in the binary alloy phase diagram, such as a gold plating layer / electroless nickel plating layer, is adopted. In this case, nickel and nickel phosphorus alloy may be unevenly distributed on the surfaces of the metal substrates 1 and 11. However, if there is no problem in the use of the metal laminate composed of the metal substrates 1 and 11 after diffusion bonding, a combination of a gold plating layer / electroless nickel plating layer or the like can be employed as the insert layer.

FIG. 2 is a process diagram for explaining another embodiment of the metal substrate bonding method of the present invention.
In this embodiment, three metal substrates 21, 31, 41 are joined, and the metal substrates 31, 41 have processed portions 32, 42 on the surfaces to be joined 31a, 41a, respectively (FIG. 2). (A)). In the insert layer forming step, the insert layer 23 is formed by laminating the first metal plating layer 24 and the second metal plating layer 25 in this order on the surface including the bonded surface 21 a of the metal substrate 21. In addition, the insert layer 33 is formed by laminating the first metal plating layer 34 and the second metal plating layer 35 in this order on the surface including the bonded surfaces 31 a and 31 b of the metal substrate 31. Further, the insert layer 43 is formed by laminating the first metal plating layer 44 and the second metal plating layer 45 in this order on the surface including the bonded surface 41 a of the metal substrate 41. (FIG. 2 (B)).
As the metal substrates 21, 31, 41, the same ones as the metal substrates 1, 11 in the above embodiment can be used.
The processing parts 32 and 42 that the metal substrates 31 and 41 have on the bonded surfaces 31a and 41a are concave portions in the illustrated example, but may be through holes or the like. Moreover, the recessed part shape of the process parts 32 and 42 is not specifically limited, For example, the groove | channel shape etc. which comprise a flow path may be sufficient.
The formation of the insert layers 23, 33, 43 on the metal substrates 21, 31, 41 can be performed in the same manner as the formation of the insert layers 3, 13 on the metal substrates 1, 11 in the above-described embodiment.

  Next, in the present invention, the insert layer 23 on the bonded surface 21 a of the metal substrate 21 is brought into contact with the insert layer 33 of the bonded surface 31 a of the metal substrate 31, and the bonded surface 31 b of the metal substrate 31 is contacted. Heating is performed in a state where the metal substrates 21, 31, and 41 are overlapped so that the insert layer 33 and the insert layer 43 of the bonded surface 41 a of the metal substrate 41 are brought into contact with each other. Thereby, the insert layer 23 and the insert layer 33, and the insert layer 33 and the insert layer 43 are diffusion-bonded (FIG. 2C). The diffusion bonding of the insert layers 23, 33, 43 can be performed in the same manner as the diffusion bonding of the insert layers 3, 13 in the above-described embodiment.

  In the metal substrate bonding method of the present invention, the insert layers 23, 33, 43 located on the bonded surfaces 21a, 31a, 31b, 41a of the metal substrates 21, 31, 41 are diffusion-bonded to each other. , 41 can be bonded with reference to the melting temperature of the insert layers 23, 33, 43, and the pressure required for diffusion bonding is diffusion bonding between the metal substrates 21, 31, 41. Compared to the case, it can be greatly reduced. Therefore, diffusion bonding can be reliably performed also in the region A and the region B surrounded by the chain line in FIG. That is, as shown in FIG. 2C, the region where the processing part 32 of the metal substrate 31 is located and the region where the processing part 42 of the metal substrate 41 is located are in the stacking direction of the metal substrates 21, 31, 41. , Has become a disagreement. The region A coincides with the region where the processing part 32 of the metal substrate 31 is located in the stacking direction of the metal substrate, and the region B is the region where the processing part 42 of the metal substrate 41 is located in the stacking direction of the metal substrate. Is consistent with For this reason, even if a pressure is applied to the laminated metal substrates 21, 31, 41, the pressure between the metal substrates is reduced in the regions A and B due to the presence of the processed portions 32, 42. In such a state, in the conventional bonding method in which the metal substrates are directly diffusion bonded to each other, it is difficult to obtain a desired pressure resistance performance and corrosion resistance performance due to a gap between the metal substrates due to bonding failure in the regions A and B. Met. On the other hand, in the present invention, since the pressure required for diffusion bonding the insert layers 23, 33, 43 is low, diffusion bonding can be reliably performed also in the above-described region A and region B. In the above example, the region where the processing parts 32 and 42 are located is completely inconsistent in the stacking direction. However, in the case where a part of the region where the processing parts 32 and 42 are located is not matching in the stacking direction. The same is true.

Further, in the present invention, the insert layers 23, 33, 43 are formed directly on the metal substrates 21, 31, 41, so that the desired pressure resistance and corrosion resistance can be obtained by performing diffusion bonding between the insert layers. Can be obtained.
Also in this embodiment, the constituent metals of the insert layers 23, 33, 43 diffused and bonded as described above may be diffused in the metal substrates 21, 31, 41 (FIG. 2D). Thereby, the intermetallic battery corrosion of a metal substrate and insert layer material can be avoided, and the metal laminated body which comprised the outstanding pressure | voltage resistant performance and corrosion resistance performance can be obtained. The diffusion of the constituent metals of the insert layers 23, 33, 43 into the metal substrates 21, 31, 41 is similar to the diffusion of the constituent metals of the insert layers 3, 13 into the metal substrates 1, 11 in the above-described embodiment. It can be carried out.
Embodiments of the above-described metal substrate bonding method are merely examples, and the present invention is not limited to such embodiments.

[Metal laminate]
FIG. 3 is a partial cross-sectional view for explaining an embodiment of the metal laminate of the present invention.
The metal laminate of the present invention is obtained by bonding a plurality of metal substrates. In FIG. 3, the metal laminate 101 is obtained by diffusion bonding of four metal substrates 102A, 102B, 102C, and 102D. .
As these metal substrates 102A, 102B, 102C, and 102D, the same materials as those described as the metal substrates 1 and 11 in the metal substrate bonding method of the present invention can be used.
Of the metal substrates 102A, 102B, 102C, and 102D, the metal substrate 102A has a workpiece 103a, the metal substrate 102B has a processed portion 103b, and the metal substrate 102C has a processed portion 103c. The regions where these processed parts 103a, 103b, and 103c are located are inconsistent in the stacking direction of the four metal substrates 102A, 102B, 102C, and 102D (the direction of arrow a in the figure).

Such a metal laminate 101 of the present invention is obtained by diffusion bonding the four metal substrates 102A, 102B, 102C, and 102D by the metal substrate bonding method of the present invention. Therefore, intermetallic battery corrosion between the metal substrate and the insert layer material can be avoided, and excellent pressure resistance performance and corrosion resistance performance are provided. In particular, since the bonding strength between the metal substrates in the region surrounded by the chain line in the figure is as excellent as the bonding strength in other regions, crevice corrosion due to the generation of voids at the substrate interface is prevented. Therefore, for example, the metal laminate of the present invention having a hollow structure that functions as a flow path has excellent pressure resistance and corrosion resistance.
The above-described embodiments of the metal laminate are examples, and the present invention is not limited to such embodiments. Therefore, the number of metal substrates constituting the metal laminate, the presence / absence of a processing portion provided in the metal substrate, the shape, and the like can be appropriately set according to the purpose of use of the metal laminate.
Moreover, although the material of the some metal substrate which comprises a metal laminated body is the same normally, according to the use of a metal laminated body, the material of a structure metal substrate may differ.

Next, the present invention will be described in more detail by showing specific examples.
[Example 1]
A stainless steel substrate having a thickness of 0.15 mm (SUS316L material (150 mm × 150 mm), melting point 1370 ° C.) was prepared as a metal substrate, and a metal substrate having a recess as a processing site and a metal substrate having no processing site were used. A metal substrate having a recess has a line-shaped recess having a depth of 100 μm, a width of 200 μm, and a length of 5000 μm by etching on one main plane of the stainless steel substrate. A total of 100 pieces of 10 in the width direction and 10 in the length direction were formed. The pitch of the recesses is a distance corresponding to the distance between the centers of the recesses, and the same applies to the following description.

<Formation of insert layer>
First, a hydrochloric acid-based gold plating solution having the following composition was prepared as a hydrochloric acid-based gold plating solution.
(Composition of hydrochloric acid-based gold plating solution)
・ Metallic gold: 2.5 g / mL
・ Hydrochloric acid: 35 g / mL
・ Cobalt: 0.1 g / mL
As a pretreatment, the above stainless steel substrate was subjected to an alkali cleaning treatment (normal temperature, 30 seconds), and then a hydrochloric acid immersion treatment (immersion in a 10% hydrochloric acid aqueous solution for 30 seconds). After this pretreatment, it was washed with water, and then the stainless steel substrate was immersed in the hydrochloric acid-based gold plating solution for 10 seconds, washed with water, and then observed with a scanning electron microscope. As a result, micropitting occurred on the surface of the stainless steel substrate. The degree was confirmed to be 5 or less per unit area (mm ² ).

In addition, the above stainless steel substrate is pretreated and then washed with water. Immediately after that, a gold plating layer (thickness 0.05 μm as a first metal plating layer is formed using the hydrochloric acid-based gold plating solution under the following conditions. ) Was formed on the entire surface of the stainless steel substrate. The melting point of this gold plating layer was 961 ° C.
(Gold plating conditions)
・ Current density: 3A / dm ²
・ Processing time: 10 seconds

Next, a silver plating solution having the following composition was prepared as a silver plating solution.
(Composition of silver plating solution)
・ Tris (3-hydroxypropyl) phosphine 15g / mL
・ Sulfuric acid: 30 g / mL
・ Silver sulfate: 5g / mL
A silver plating layer (thickness 0.35 μm) as a second metal plating layer was formed on the first metal plating layer under the following conditions using the above silver plating solution. The melting point of this silver plating layer was 1064 ° C.
(Conditions for second metal plating)
・ Current density: 3A / dm ²
・ Processing time: 120 seconds
As a result, an insert layer having a thickness of 0.4 μm was formed on the entire surface of the stainless steel substrate.

<Diffusion bonding between insert layers>
Prepare two metal substrates with insert layers as described above on a stainless steel substrate with recesses as processing sites, and one metal substrate with insert layers as described above on stainless steel substrates without processing sites. As shown in FIG. 2C, the three metal substrates are overlaid so that the insert layer is brought into contact so that the regions where the recesses are located in the two metal substrates are not matched in the stacking direction. The diffusion bonding was performed under the following conditions.
(Diffusion bonding conditions)
・ Heating temperature: 1100 ℃
・ Degree of vacuum: 10 ^-4 Pa
-Holding time of heating and pressurization: 8 hours-Cooling time to room temperature: 10 hours In this way, three stainless steel substrates were joined to produce a metal laminate (sample 1).
<Diffusion into metal substrate>
A metal laminate (sample) was formed in the same manner as described above except that the constituent metal of the insert layer existing between the three stainless steel substrates was diffused into the stainless steel substrate by setting the holding time in the diffusion bonding to 12 hours. 1 ′) was produced.

[Example 2]
As metal substrates, two types of metal substrates were prepared as in the case of Example 1 depending on the presence or absence of recesses.
<Formation of insert layer>
First, an acidic silver plating solution having the following composition was prepared as an acidic silver plating solution.
(Composition of acidic silver plating solution)
・ Silver sulfate: 5.0 g / L
・ Sulfuric acid: 30 g / L
・ Tris (3-hydroxypropyl) phosphine: 15 g / L
As a pretreatment, the above stainless steel substrate was subjected to an alkali cleaning treatment (normal temperature, 30 seconds), and then a hydrochloric acid immersion treatment (immersion in a 10% hydrochloric acid aqueous solution for 30 seconds). After this pretreatment, it was washed with water, and then the stainless steel substrate was immersed in the acidic silver plating solution for 10 seconds, washed with water, and then observed with a scanning electron microscope. As a result, the occurrence of micropitting corrosion on the surface of the stainless steel substrate was observed. Was confirmed to be 5 or less per unit area (mm ² ).

Moreover, after pre-processing to said stainless steel substrate, it wash | cleans with water, and immediately after that, using the said acidic silver plating solution, the silver plating layer (thickness 0.35 micrometer) as a 1st metal plating layer on the following conditions Was formed on the entire surface of the stainless steel substrate. The melting point of this silver plating layer was 1064 ° C.
(Conditions for silver plating)
・ Current density: 3A / dm ²
・ Processing time: 150 seconds
Next, a cyan gold plating solution having the following composition was prepared as a gold plating solution.
(Composition of cyan gold plating solution)
・ Metallic gold: 6.0 g / mL
・ Cobalt: 0.5g / mL

A gold plating layer (thickness 0.05 μm) as a second metal plating layer was formed on the first metal plating layer under the following conditions using the above cyan-based gold plating solution. The melting point of this gold plating layer was 961 ° C.
(Conditions for second metal plating)
・ Current density: 15 A / dm ²
・ Processing time: 10 seconds
As a result, an insert layer having a thickness of 0.4 μm was formed on the entire surface of the stainless steel substrate.

<Diffusion bonding between insert layers>
Prepare two metal substrates with insert layers as described above on a stainless steel substrate with recesses as processing sites, and one metal substrate with insert layers as described above on stainless steel substrates without processing sites. As shown in FIG. 2C, the three metal substrates are overlaid so that the insert layer is brought into contact so that the regions where the recesses are located in the two metal substrates are not matched in the stacking direction. The diffusion bonding was performed under the following conditions.
(Diffusion bonding conditions)
・ Heating temperature: 1100 ℃
・ Degree of vacuum: 10 ^-4 Pa
-Holding time of heating and pressurization: 8 hours-Cooling time to room temperature: 10 hours In this way, three metal substrates were joined to produce a metal laminate (sample 2).
<Diffusion into metal substrate>
A metal laminate (sample) was formed in the same manner as described above except that the constituent metal of the insert layer existing between the three stainless steel substrates was diffused into the stainless steel substrate by setting the holding time in the diffusion bonding to 12 hours. 2 ′) was produced.

[Example 3]
As metal substrates, two types of metal substrates were prepared as in the case of Example 1 depending on the presence or absence of recesses.
<Formation of insert layer>
In the same manner as in Example 1, a gold plating layer (thickness 0.05 μm) as a first metal plating layer was formed on the entire surface of the stainless steel substrate. The melting point of this gold plating layer was 961 ° C.
Next, the gold plating layer as the first metal plating layer is pretreated using a known hydrochloric acid-based gold plating solution, and then manufactured by Okuno Pharmaceutical Co., Ltd. as an electroless nickel plating solution. An electroless nickel plating layer (thickness: 0.35 μm, phosphorus content: 10% by weight) as a second metal plating layer was formed using Top Nicolon SA-98. The melting point of the electroless nickel plating layer was 900 ° C.
As a result, an insert layer having a thickness of 0.4 μm was formed on the entire surface of the stainless steel substrate.

<Diffusion bonding between insert layers>
Prepare two metal substrates with insert layers as described above on a stainless steel substrate with recesses as processing sites, and one metal substrate with insert layers as described above on stainless steel substrates without processing sites. As shown in FIG. 2C, the three metal substrates are overlaid so that the insert layer is brought into contact so that the regions where the recesses are located in the two metal substrates are not matched in the stacking direction. The diffusion bonding was performed under the following conditions.
(Diffusion bonding conditions)
・ Heating temperature: 1200 ℃
・ Degree of vacuum: 10 ^-4 Pa
-Holding time of heating and pressurization: 8 hours-Cooling time to room temperature: 10 hours In this way, three metal substrates were joined to produce a metal laminate (sample 3).
<Diffusion into metal substrate>
A metal laminate (sample) was formed in the same manner as described above except that the constituent metal of the insert layer existing between the three stainless steel substrates was diffused into the stainless steel substrate by setting the holding time in the diffusion bonding to 12 hours. 3 ') was produced.

[Comparative Example 1]
As metal substrates, two types of metal substrates were prepared as in the case of Example 1 depending on the presence or absence of recesses.
As shown in FIG. 2 (C), two metal substrates without forming an insert layer and having two metal substrates having recesses as processing sites and one metal substrate having no processing sites are formed. The regions in which the recesses are located are overlapped so that they do not match in the stacking direction, and diffusion bonding is performed under the following conditions.
(Diffusion bonding conditions)
・ Heating temperature: 1300 ℃
・ Degree of vacuum: 10 ^-4 Pa
-Holding time of heating and pressurization: 8 hours-Cooling time to room temperature: 10 hours Thereby, three metal substrates were joined to produce a metal laminate (Comparative Sample 1).
Further, a metal laminate (Comparative Sample 1 ′) was produced in the same manner as described above except that the cooling time to room temperature was shortened to 18 hours.

[Comparative Example 2]
As metal substrates, two types of metal substrates were prepared as in the case of Example 1 depending on the presence or absence of recesses.
<Formation of insert layer>
An acidic silver plating solution similar to the acidic silver plating solution used in Example 2 was prepared.
The above stainless steel substrate is pretreated and then washed with water. Immediately after that, a silver plating layer (thickness 0.5 μm) as an insert layer is formed on the stainless steel substrate under the following conditions using the acidic silver plating solution. Formed on the entire surface. The melting point of this silver plating layer was 1064 ° C.
(Conditions for silver plating)
・ Current density: 3A / dm ²
・ Processing time: 120 seconds

<Diffusion bonding between insert layers>
Prepare two metal substrates with insert layers as described above on a stainless steel substrate with recesses as processing sites, and one metal substrate with insert layers as described above on stainless steel substrates without processing sites. As shown in FIG. 2C, the three metal substrates are overlaid so that the insert layer is brought into contact so that the regions where the recesses are located in the two metal substrates are not matched in the stacking direction. The diffusion bonding was performed under the following conditions.
(Diffusion bonding conditions)
・ Heating temperature: 1200 ℃
・ Degree of vacuum: 10 ^-4 Pa
-Holding time of heating and pressurization: 8 hours-Cooling time to room temperature: 10 hours In this way, three metal substrates were joined to produce a metal laminate (Comparative Sample 2).
<Diffusion into metal substrate>
A metal laminate (comparison) was performed in the same manner as described above except that the constituent metal of the insert layer existing between the three stainless steel substrates was diffused into the stainless steel substrate by setting the holding time in the diffusion bonding to 12 hours. Sample 2 ') was prepared.

[Comparative Example 3]
In the same manner as in Example 1, except that a gold plating layer (0.05 μm) was formed as the first metal plating layer and the insert layer was formed without forming the silver plating layer as the second metal plating layer. A laminate (Comparative Sample 3) was produced.
<Diffusion into metal substrate>
A metal laminate is formed in the same manner as described above except that the constituent metal of the insert layer existing between the three stainless steel substrates is diffused into the stainless steel substrate by setting the holding time in diffusion bonding between the insert layers to 12 hours. (Comparative sample 3 ') was produced.

[Evaluation]
About the metal laminated body produced as mentioned above, the presence or absence of the space | gap part of a joining interface, joining strength, and the presence or absence of the crack of a metal substrate surface were evaluated as follows, and the result was shown in Table 1.
(Evaluation of the presence or absence of voids at the bonding interface)
When the metal laminate is cut perpendicularly to the bonding surface (cutting pitch: 10 mm) and the bonding interface is observed with FIB (focused ion beam), the number of voids per observation distance is 1 / mm or less. It was judged that there was no part.
(Evaluation of bonding strength)
Bending test specified by JIS for a metal laminate (between 4 and 10 mm in bending radius, bend 90 ° against a vise and bend back to the original, and bend 90 ° to the opposite side and return again. This was repeated twice, and the case where there was no separation at the joint surface and no deviation from the joint surface was defined as good joint strength.
(Evaluation of cracks)
The entire surface of the metal laminate was observed with a magnifying microscope about 100 times, and a case where the number of cracks was 1 or less was judged as no crack generation.

As shown in Table 1, Sample 1, Sample 1 ′, Sample 2, Sample 2 ′, Sample 3, and Sample 3 ′ had good bonding strength, no voids, and no cracks were observed.
On the other hand, the comparative sample 1 has insufficient bonding strength in the stacking direction of the region where the recess exists, and the time required for diffusion bonding is long. In the comparative sample 1 ′, cracks were observed as a result of shortening the cooling time.
In Comparative Sample 2, there was an insert layer residue of the silver plating layer, and voids were seen on the adjacent joint surfaces even at the joint, and the joint strength was insufficient. The comparative sample 2 'had a long time required for diffusion bonding, but the bonding strength was insufficient.

  Comparative sample 3 has a thin insert layer and does not provide sufficient bonding strength, and comparative sample 3 'has good bonding strength due to the long time required for diffusion bonding, but the gap is not sufficiently filled. There wasn't. If the insert layer made of the gold plating layer in comparative sample 3 is 0.5 μm ignoring the material cost, it is the same as sample 1, sample 1 ′, sample 2, sample 2 ′, sample 3 and sample 3 ′. The bonding strength was good, there were no voids, and no cracks were observed.

  The present invention can be used in various manufacturing fields that require a diffusion bonding process between metal substrates.

1, 11, 21, 31, 41 ... Metal substrate 1a, 11a, 21a, 31a, 31b, 41a ... Surface to be joined 3, 13, 23, 33, 43 ... Insert layer 4, 14, 24, 35, 44 ... No. 1 metal plating layer 5, 15, 25, 35, 45 ... 2nd metal plating layer 32, 42 ... processing site 101 ... metal laminate 102A, 102B, 102C, 102D ... metal substrate 103a, 103b, 103c ... processing site

Claims (9)

A step of laminating a first metal plating layer and a second metal plating layer in this order on at least the surfaces to be joined of the plurality of metal substrates to form an insert layer;
In a state where the metal substrates are stacked so as to contact the insert layers of the bonded surfaces, the metal substrates are heated to diffusely bond the insert layers to each other.
The melting point of the first metal plating layer and the melting point of the second metal plating layer constituting the insert layer are both lower than the melting point of the metal substrate.   The metal substrate bonding method according to claim 1, wherein the constituent metal of the insert layer that has been diffusion bonded is diffused into the metal substrate.   The metal substrate bonding method according to claim 1, wherein the metal substrate is one of a stainless steel substrate and a nickel substrate.   The combination of the first metal plating layer / second metal plating layer constituting the insert layer is any of gold plating layer / silver plating layer, silver plating layer / gold plating layer, and gold plating layer / electroless nickel plating layer. The metal substrate bonding method according to any one of claims 1 to 3, wherein the metal substrate is bonded.   5. A gold plating layer, which is the first metal plating layer, is formed using a hydrochloric acid-based gold plating solution, and the thickness of the gold plating layer is in the range of 0.015 to 0.15 [mu] m. A method for joining metal substrates as described in 1. above.   The metal according to any one of claims 1 to 5, wherein the first metal plating layer and the second metal plating layer constituting the insert layer are completely solid solution in a binary alloy phase diagram. Substrate bonding method.   The heating temperature for diffusion bonding the insert layers is set within a range of ± 100 ° C. with respect to the lower melting point of the melting point of the first metal plating layer and the second metal plating layer constituting the insert layer. The metal substrate bonding method according to claim 1, wherein the metal substrate is bonded.   A metal laminate comprising a plurality of metal substrates bonded together by the metal substrate bonding method according to claim 1.   It has three or more layers of metal substrates, and at least two or more layers of metal substrates have a processed portion, and at least a part of a region where the processed portion is located in each metal substrate is mismatched in the stacking direction. The metal laminate according to claim 8.

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