JP2016107290A - Metal material joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and simple metal material joining method capable of forming a joint part having high reliability and mechanical characteristics even at a low joining temperature by reducing a void or a residual organic component in a joint layer and eliminating the necessity of applying, e.g., a joining composition on a joint surface.SOLUTION: The metal material joining method includes: the first step of forming a plating layer on the joint surface of a first joint material and/or a second joint material; the second step of carrying out a dealloying processing for the plaiting layer to set it as a nano porous body metal layer; and the third step of heating the nano porous body metal layer to 50-400°C in the abutted state of the first joint material and the second joint material via the nano porous body metal layer and pressurizing the first joint material and the second joint material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a low-temperature bonding method for metal materials, and more specifically, by reducing voids and residual organic components in a bonding layer, it is possible to form a bonded portion having high reliability and mechanical characteristics at a low bonding temperature. In addition, the present invention relates to an inexpensive and simple method for joining metal materials, which does not require application of a bonding composition to a bonded interface.

  Conventionally, in order to mechanically and / or electrically and / or thermally bond metal parts and metal parts represented by copper materials and copper-coated parts, solder, conductive adhesive, silver paste and An anisotropic conductive film or the like is used.

  In particular, adhesives, pastes, and films containing conductive fillers made of solder and metal are used for joining parts that require electrical connection. Furthermore, since metals generally have high thermal conductivity, adhesives, pastes, and films containing these solders and conductive fillers may be used to increase heat dissipation.

  On the other hand, for example, when a high-luminance lighting device or a light-emitting device is manufactured using a light-emitting element such as an LED, or a semiconductor device is manufactured using a semiconductor element that operates at a high temperature and is called a power device. In some cases, the amount of heat generation tends to increase. Attempts have been made to improve the efficiency of devices and elements to reduce heat generation. However, at present, sufficient results have not been achieved, and the operating temperature of devices and elements has risen.

  Further, from the viewpoint of preventing device damage during bonding, a bonding material that can ensure sufficient bonding strength at a low bonding temperature (for example, 350 ° C. or lower) is required. Therefore, the bonding material for bonding devices and elements is required to have heat resistance that can withstand the increase in operating temperature due to the operation of the device after bonding and maintain sufficient bonding strength as the bonding temperature decreases. However, there are many cases where conventional bonding materials are not sufficient. For example, solder joins members through a process of heating the metal to the melting point or higher (reflow process). Generally, the melting point is inherent to the composition, so heating (joining) when trying to increase the heat-resistant temperature. The temperature will rise.

  Furthermore, when several layers of elements and substrates are bonded using solder, it is necessary to go through the heating process for the number of layers to be overlapped. In order to prevent melting of the already bonded portion, the solder used for the next bonding It is necessary to lower the melting point (joining temperature) of the solder, and the number of types of solder composition is required by the number of layers to be overlaid, which makes handling complicated.

  On the other hand, in the conductive adhesive, silver paste and anisotropic conductive film, the members are joined together by using thermosetting such as epoxy resin contained, but when the use temperature of the obtained device or element rises, the resin component May decompose and deteriorate. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-63688) proposes fine particles that are used as a main material of a bonding material so that higher bonding strength can be obtained when bonded members are bonded to each other. The problem of decomposition and deterioration of the resin component at the time of use temperature rise has not been solved.

  Conventionally, solder containing lead has been used as high-temperature solder used at high operating temperatures. Since lead is toxic, the trend toward solder-free solder is remarkable. Since there is no other good alternative material for high-temperature solder, lead solder is still used, but from the viewpoint of environmental problems, a bonding material that does not use lead is eagerly desired.

  In recent years, as an alternative material for high-temperature solder, a bonding material using metal nanoparticles centered on noble metals such as silver and gold has been developed (for example, Patent Document 2: JP 2012-046779 A). However, since metal nanoparticles are not only expensive, but also easily aggregate at room temperature, in order to maintain a dispersed state for a long period of time, the surface of the metal nanoparticles is coated with an organic layer, and a suitable dispersant for the solvent. Need to be added.

  The bonding layer formed by sintering metal nanoparticles has superior characteristics compared to conventional solders, such as having a heat resistance temperature corresponding to the melting point of the metal, while the organic layer and the dispersing agent are bonded at the sintering stage. There is a problem that voids are formed. In addition, there is an unavoidable problem that the bonding temperature depends on the decomposition temperature of the organic layer and the dispersant.

JP 2008-63688 A JP 2012-046779 A

  In view of the above situation, the object of the present invention is to enable formation of a joint having high reliability and mechanical characteristics by reducing voids and residual organic components in the joining layer even at a low joining temperature. An object of the present invention is to provide an inexpensive and simple method for joining metal materials, which does not require application of a joining composition to a joining surface.

  As a result of earnest research on the method for joining metal materials to achieve the above-mentioned object, the present inventor can form a nanoporous metal layer in which metal nanoparticles are arranged in a three-dimensional manner on the surface to be joined. It has been found that it is extremely effective in achieving the above object, and has reached the present invention.

That is, the present invention
A first step of forming a plating layer on a bonded surface of the first bonded material and / or the second bonded material;
A second step in which the plating layer is subjected to decomponent corrosion treatment to form a nanoporous metal layer;
While heating the nanoporous metal layer to 50 to 400 ° C. in a state where the first bonded material and the second bonded material are brought into contact with each other through the nanoporous metal layer, Including a third step of pressurizing the first material to be joined and the second material to be joined,
A metal material joining method characterized by the above.

  In the metal material joining method of the present invention, a deporous corrosion treatment (dealloying) is performed on the plating layer formed on the surface to be joined to form a nanoporous metal layer, and the nanoporous metal layer is used. In order to achieve the joining, handling at the time of joining is extremely easy, and it is not necessary to apply the joining composition paste to the joined surfaces or insert the joining composition sheet or the like.

  Although it is extremely difficult to three-dimensionally arrange individually generated metal nanoparticles, a nanoporous metal layer can be easily obtained by using decomponent corrosion of the plating layer. In addition, since the nanoporous metal layer obtained by decomponent corrosion of the plating layer is basically planar, it can be suitably used as a composition for joining between materials to be joined. The nanoporous metal layer may be formed on the entire surface to be joined, or may be formed on a part thereof.

  Here, the decomponent corrosion is based on the selective dissolution of alloy elements using an appropriate corrosive solution. Reported by Erlebacher et al., Nature, 410 (2001), 40, and a nanoporous metal layer formed using this technique is preferably used in the bonding method of the present invention.

  Moreover, in the joining method of the metal material of this invention, it is preferable to further have a structure | tissue adjustment process which anneals to the said plating layer between said 1st process and said 2nd process. The size of the tissue constituting the nanoporous metal layer can be arbitrarily adjusted by the annealing treatment, and can be optimized for bonding applications.

  Moreover, in the joining method of the metal material of this invention, it is preferable that the temperature of the said annealing process shall be 50-150 degreeC. By setting the temperature of the annealing treatment to 50 to 150 ° C., moderate coarsening of the plating layer structure and atomic rearrangement occur, and the nanoporous metal layer having an excellent low-temperature sintering function by the subsequent decomponent corrosion treatment Can be obtained.

  Moreover, in the joining method of the metal material of this invention, it is preferable that the said nanoporous metal layer contains the metal nanoparticle with an average particle diameter of 5-500 nm arranged in three dimensions, and an average particle diameter is 5 More preferably, it contains metal particles of ˜50 nm. When the metal nanoparticles have these average particle diameters, the nanoporous metal layer exhibits an excellent low-temperature sintering function at the bonding temperature. In addition, by using a nanoporous metal layer in which metal nanoparticles are arranged three-dimensionally, there is no need to use an organic coating layer, a dispersant, etc. to ensure the dispersibility of the metal nanoparticles, Voids and residual organic substances in the bonding layer can be greatly reduced.

  Various conventionally known bonding compositions may be further applied to the bonded interface as long as the effects of the present invention are not impaired, but the bonding is achieved only by the low-temperature sintering function of the nanoporous metal layer. It is preferable. By using only the nanoporous metal layer that does not require the use of organic solvents or dispersants as the bonding composition, the organic layer and the dispersant remain in the bonding layer during the sintering stage, forming voids. Can be effectively solved. In addition, the inevitable problem of the joining method using metal nanoparticles, in which the joining temperature depends on the decomposition temperature of the organic layer and the dispersant or the like, can be solved.

In the metal material joining method of the present invention, the plating layer to be subjected to decomponent corrosion treatment is preferably a binary alloy, and more preferably an Au—Ag alloy. By decomponent corrosion of the binary alloy, one element is mainly dissolved and removed, and a nanoporous metal layer composed of metal nanoparticles mainly composed of the other element can be efficiently obtained. In addition, a nanoporous metal layer mainly composed of gold (Au) can be efficiently obtained by decomponent corrosion of the Au—Ag alloy with, for example, nitric acid (HNO ₃ ).

  Furthermore, in the joining method of the metal material of this invention, it is preferable that said 1st to-be-joined material and / or said 2nd to-be-joined material are copper materials. The material to be bonded according to the present invention is not particularly limited as long as the nanoporous metal layer can be formed on the surface to be bonded, and various conventionally known metal materials can be used. Can be obtained.

The present invention also provides:
Having a binary alloy plating layer on at least a portion of the metal substrate;
At least the vicinity of the surface of the binary alloy plating layer has a nanoporous structure containing metal nanoparticles having an average particle size of 5 to 500 nm arranged three-dimensionally;
Also provided is a metal member for joining a metal material.

  The presence of the plating layer having a nanoporous structure on the surface of the metal substrate makes it possible to obtain a good bonded body without applying the bonding composition to the bonded surfaces. Here, when a plating layer having a nanoporous structure is formed on one surface of a metal member for joining a metal material, the metal member for metal joining and another metal member are joined via the plating layer. When a plating layer having a nanoporous structure is formed on a plurality of surfaces of a metal member for joining a metal material, it can be used as a joint member for joining a plurality of metal members.

  In the metal member for joining a metal material of the present invention, the binary alloy plating layer is preferably an Au-Ag alloy plating layer. A nanoporous structure mainly composed of gold (Au) is formed in the vicinity of the surface of the Au—Ag alloy plating layer, and the nanoporous structure can be suitably used as a bonding layer.

  According to the present invention, it is possible to form a bonding portion having high reliability and mechanical characteristics by reducing voids and residual organic components in the bonding layer even at a low bonding temperature, and a composition for bonding to a surface to be bonded. Therefore, it is possible to provide an inexpensive and simple method for joining metal materials that does not require coating or the like.

It is process drawing of the joining method of the metal material of this invention. It is a schematic sectional drawing of the metal member for metal material joining of this invention. It is a SEM photograph of the Au-Ag alloy plating layer surface of sample 1 for evaluation. It is a graph which shows Ag content rate of the Au-Ag alloy plating layer surface vicinity. It is a graph which shows the shear strength of a joint joint. It is a SEM photograph of the Au-Ag alloy plating layer surface of sample 2 for evaluation. It is a SEM photograph of the Au-Ag alloy plating layer surface of sample 3 for evaluation. It is a SEM photograph of the Au-Ag alloy plating layer surface of sample 4 for evaluation.

  Hereinafter, a preferred embodiment of the metal material joining method of the present invention will be described in detail. In addition, in the following description, only one embodiment of the present invention is shown, and the present invention is not limited by these, and redundant description may be omitted.

(1) Joining Method FIG. 1 shows a process diagram of a joining method of metal materials of the present invention. The metal material joining method of the present invention includes a first step (S01) in which a plating layer is formed on a surface to be joined of the first material to be joined and / or the second material to be joined, and a decomponent corrosion treatment on the plating layer. In the second step (S02) to form a nanoporous metal layer, and the first porous material and the second porous material are brought into contact with each other through the nanoporous metal layer. The body metal layer is heated to 50 to 400 ° C., and includes a third step (S03) of pressurizing the first bonded material and the second bonded material. Each step will be described below.

(1-1) First step (S01: plating layer forming step)
The first step (S01) is a step of forming a plating layer on the bonded surface of the first bonded material and / or the second bonded material. The plating method to be used is not particularly limited, and the plating layer may be formed by various conventionally known methods.

  Here, the composition of the plating layer is not particularly limited as long as a specific element is selectively corroded by decomponent corrosion treatment, but is preferably a binary alloy, more preferably an Au-Ag alloy. preferable. By making the plating layer a binary alloy, one element can be dissolved and removed mainly by decomponent corrosion, and the nanoporous metal layer composed of metal nanoparticles mainly composed of the other element can be efficiently used. Can be obtained. In addition, by using a binary alloy, it is easy to grasp the composition after decomponent corrosion.

  Examples of metal materials that can obtain a nanoporous metal layer by decomponent corrosion include Au-Ag-Pt, Au-Cu, Au-Zn, Au-Al, Ag-Al, Ag-Zn, Cu-Al, Cu -Mg, Cu-Mn, Cu-Zn, Cu-Sn, Pt-Cu, Pt-Si, Pt-Al, Pt-Zn, Pd-Ag, Pt-Co, Pd-Al, Pd-Ni-P, Ni -Al, Ni-Cu, etc. can be illustrated.

The Au—Ag alloy plating layer may be formed by various conventionally known plating methods. For example, in a plating bath, metal gold 1 to 5 g / L, metal silver 2 to 10 g / L, cyan 5 A composition of 15 g / L, an appropriate amount of brightener can be used, and a liquid temperature of 20 to 30 ° C., −300 to −900 mV vs. The potential of Ag / AgCl, by plating at a current density of 0.5~1A / dm ^2, it is possible to form the Au-Ag alloy plating layer.

  The plating layer may be formed on the entire surface to be joined, or may be partially formed in an arbitrary region. The thickness of the plating layer is not particularly limited, but is preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. When the thickness of the plating layer is 0.1 μm or more, stable composition control of the alloy can be performed, and when it is 0.5 μm or less, the mechanical strength of the nano-porous structure can be ensured. be able to.

(1-2) Second step (S02: Decomponent corrosion treatment)
The second step (S02) is a step of obtaining a nanoporous metal layer by subjecting the plating layer formed in the first step (S01) to decomponent corrosion treatment.

What is necessary is just to select suitably the corrosive liquid used for a decomponent corrosion process according to the plating layer used as a process target. For example, a nanoporous metal layer mainly composed of gold (Au) can be efficiently obtained by decomponent corrosion of an Au—Ag alloy with nitric acid (HNO ₃ ).

  Examples of metal materials that can obtain a nanoporous metal layer by decomponent corrosion include Au-Ag-Pt, Au-Cu, Au-Zn, Au-Al, Ag-Al, Ag-Zn, Cu-Al, Cu -Mg, Cu-Mn, Cu-Zn, Cu-Sn, Pt-Cu, Pt-Si, Pt-Al, Pt-Zn, Pd-Ag, Pt-Co, Pd-Al, Pd-Ni-P, Ni -Al, Ni-Cu and the like can be exemplified, but the nanoporous Au layer is formed by decomponent corrosion such as Au-Ag-Pt, Au-Cu, Au-Zn and Au-Al, and the Ag-Al and Ag -Nanoporous Ag layer by decomponent corrosion such as Zn, and Nanoporous Cu layer by Pt-Cu, Pt-Si by decomponent corrosion such as Cu-Al, Cu-Mg, Cu-Mn and Cu-Zn. , Pt-Al, Pt-Zn, Pd-Ag and Nanoporous Pt layer by decomponent corrosion such as Pt-Co, etc., Nanoporous Pd layer by decomponent corrosion such as Pd-Al and Pd-Ni-P, Decomponent such as Ni-Al and Ni-Cu, etc. Each nanoporous Ni layer can be obtained by corrosion.

  The nanoporous metal layer is preferably a nanoporous metal layer in which metal nanoparticles having an average particle diameter of 5 to 500 nm are three-dimensionally arranged, and metal nanoparticles having an average particle diameter of 10 to 50 nm are A nanoporous metal layer that is three-dimensionally arranged is more preferable. Metal nanoparticles generally have poor stability and dispersibility, and it is necessary to coat the surface with organic matter, etc., but the metal nanoparticles are arranged in a three-dimensional manner without using the coating or the like for a long time. Stability and dispersibility can be ensured.

  In addition, by setting the average particle size of the metal nanoparticles constituting the nanoporous metal layer to 5 to 500 nm, the low-temperature firing function inherent to the metal nanoparticles can be expressed, and by heating at about 50 to 400 ° C. Even if it exists, sintering of metal nanoparticles can be advanced. When a metal component is subjected to decomponent corrosion treatment, it is easy to obtain a nanoporous metal layer having an average particle size of metal nanoparticles of 5 nm or more. When the average particle size of metal nanoparticles is 500 nm or less, the low-temperature firing function is achieved. It is easy to be expressed. In addition, by setting the average particle diameter of the metal nanoparticles to 10 to 50 nm, both the stability of the metal nanoparticles and the low-temperature sintering function can be achieved at a high level. The average particle diameter of the metal nanoparticles can be measured from an electron micrograph, for example, and can be calculated from the electron micrograph using an image processing apparatus. In addition, the average particle diameter of the metal nanoparticle which comprises a nanoporous metal layer means the average value of the shortest diameter, when the metal nanoparticle is flat.

  Although it is extremely difficult to arrange individually generated metal nanoparticles in three dimensions, it is easy to form a nanoporous metal layer in which metal nanoparticles are arranged in three dimensions by using decomponent corrosion of the plating layer. And the labor of arranging the bonding composition on the surface to be bonded can be saved.

As described above, decomponent corrosion uses selective dissolution of alloying elements using an appropriate corrosive solution, and the corrosive solution depends on the metal material to be treated and the shape of the target nanoporous metal layer, etc. May be selected as appropriate. As the corrosive liquid, for example, HF, HCl, NaOH, HNO ₃ , H ₂ SO ₄ , citric acid, H ₂ SO ₄ + MnSO ₄ , (NH ₄ ) ₂ SO ₄ + MnSO ₄ , AgNO _3, or the like can be used.

  Although all of the plating layer may be made into the nanoporous metal layer by decomponent corrosion, only the vicinity of the surface of the plating layer may be made into the nanoporous metal layer. As long as the contact on the surface to be joined has a nanoporous structure, a good joint can be obtained by having a low-temperature firing function. In this case, the metal nanoparticles need not be fired inside the plating layer that has not undergone decomponent corrosion, and bonding can be achieved very efficiently.

(1-3) Third step (S03: joining step)
In the third step (S03), the nanoporous metal layer is heated to 50 to 400 ° C. in a state where the first bonded material and the second bonded material are brought into contact with each other through the nanoporous metal layer. And a step of pressurizing and joining the first material to be joined and the second material to be joined.

  If the joining method of the metal material of this invention is used, in joining of the metal members accompanying a heating, high joining strength can be obtained simply. That is, by sintering the nanoporous metal layer formed on the bonded surface of the first bonded material and / or the second bonded material, the first bonded material and the second bonded material. And can be joined. At this time, the intervening nanoporous metal layer may be heated by heating one or both of the first bonded material and the second bonded material.

  Moreover, in this heating, a strong joint is obtained by applying a pressure of about 0.5 to 30 MPa in the direction of sandwiching the first and second bonded materials from the outside. Can do. In addition, when firing, the temperature can be raised or lowered stepwise. Furthermore, it is also possible to apply a surfactant or a surface activator to the surface of the member to be joined.

  From the viewpoint of reducing voids and residual organic components in the bonding layer, it is preferable to bond the first bonded material and the second bonded material only through the nanoporous metal layer, Various known bonding compositions may be applied to the surfaces to be bonded. As the bonding composition, for example, a bonding composition containing metal nanoparticles as a main component can be used.

  The “application” of the bonding composition is a concept that includes a case where the bonding composition is applied in a planar shape and a case where the bonding composition is applied (drawn) linearly. The shape of the coating film made of the bonding composition in a state before being applied and fired by heating can be changed to a desired shape. Therefore, in the bonded body after firing by heating, the bonding composition is a concept including both a planar bonding layer and a linear bonding layer, and these planar bonding layer and linear bonding layer are: It may be continuous or discontinuous, and may include a continuous part and a discontinuous part.

  The first material to be joined and the second material to be joined that can use the joining method of the present invention are not particularly limited as long as the nanoporous metal layer can be baked and joined by heating. However, it is preferably a metal member having heat resistance that is not damaged by the temperature at the time of joining, and more preferably a copper member.

  In addition, the to-be-joined copper member may coat | cover copper by various methods, such as plating and vapor deposition, to base materials other than copper. Examples of such a base material include polyesters such as polyamide (PA), polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polycarbonate. (PC), polyethersulfone (PES), vinyl resin, fluororesin, liquid crystal polymer, ceramics, glass, or metal other than copper can be used.

  The bonded copper member may have various shapes such as a plate shape or a strip shape, and may be rigid or flexible. The thickness of the substrate can also be selected as appropriate. A copper member that has been subjected to a surface treatment such as a hydrophilization treatment may be used in order to improve adhesiveness or adhesion, or for other purposes.

  When the bonding composition is applied to the surfaces to be bonded, various application methods can be used. As described above, for example, dipping, screen printing, spraying, bar coating, and spin coating are used. The ink jet method, the dispenser method, the pin transfer method, the brush application method, the casting method, the flexo method, the gravure method, the syringe method, and the like can be appropriately selected and used.

  The method for performing the firing is not particularly limited. For example, firing is performed using a conventionally known oven or the like so that the temperature of the nanoporous metal layer formed on the bonded surface is, for example, 400 ° C. or less. Can be joined. The lower limit of the firing temperature is not necessarily limited, and is preferably a temperature at which the bonded metal members can be joined to each other and does not impair the effects of the present invention.

  According to the nanoporous metal layer used in the bonding method of the present invention, it is possible to realize a bonding having a bonding layer that exhibits high conductivity even by firing at a low temperature of, for example, about 50 to 400 ° C. Even if the members to be joined are weak, they can be joined. Further, the firing time is not particularly limited, and may be any firing time that can be bonded according to the firing temperature. In addition, suitable joining temperature can be judged by measuring the particle size of the metal particle which comprises a nanoporous metal layer, and when the said particle size is small, joining at lower temperature is attained.

  The atmosphere in the bonding step is not particularly limited, and can be performed in the air, under an inert gas atmosphere, under reduced pressure, or the like.

(1-4) Structure adjustment process (S01 ': annealing process)
In the structure adjustment step (S01 ′), the plating layer formed on the bonded surface in the first step (S01) is annealed to form the nanoporous metal layer obtained in the second step (S02). This is a step of arbitrarily adjusting the size of the tissue.

  The temperature of the annealing treatment is preferably 50 to 150 ° C. By setting the temperature of the annealing treatment to 50 to 150 ° C., moderate coarsening of the plating layer structure and atomic rearrangement occur, and the nanoporous metal layer having an excellent low-temperature sintering function by the subsequent decomponent corrosion treatment Can be obtained.

  More specifically, the average particle diameter of the metal nanoparticles constituting the nanoporous metal layer obtained in the second step (S02) can be set to 5 to 500 nm by annealing treatment. The atmosphere for the annealing treatment is not particularly limited and can be performed in the air or in an inert gas atmosphere.

  As mentioned above, although typical embodiment which concerns on the joining method of this invention was described, this invention is not limited only to these. For example, various metal layers (for example, plating layers) may be formed between the member to be joined and the nanoporous metal layer.

(2) Metal member for metal material joining The metal member for metal material joining of this invention is a metal member which can be used suitably for the joining method of the metal material of this invention. Below, the metal member for metal material joining is demonstrated. In addition, the part which overlaps with the description in the said joining method is abbreviate | omitted.

  FIG. 2 shows a schematic cross-sectional view of the metal member for joining metal materials of the present invention. The metal member 1 for joining a metal material has a binary alloy plating layer 4 on at least a part of a metal base 2, and at least the surface vicinity of the binary alloy plating layer 4 is three-dimensionally arranged in an average particle diameter Is a nanoporous structure region 6 containing metal nanoparticles of 5 to 500 nm.

  The presence of the binary alloy plating layer 4 having a nanoporous structure on the surface of the metal substrate 2 makes it possible to obtain a good bonded body without applying a bonding composition to the bonded surfaces. Here, when the binary alloy plating layer 4 having a nanoporous structure is formed on one surface of the metal member 1 for metal material bonding, the metal member 1 for metal bonding through the binary alloy plating layer 4. When the binary alloy plating layer 4 having the nanoporous structure is formed on the plurality of surfaces of the metal member 1 for joining the metal material, the plurality of metal members can be bonded to each other. The metal member 1 for joining metal materials can be used as a joint member to be joined.

  In the metal member 1 for joining metal materials of the present invention, the binary alloy plating layer 4 is preferably an Au—Ag alloy plating layer. A nanoporous structure mainly composed of gold (Au) is formed in the vicinity of the surface of the Au—Ag alloy plating layer, and the nanoporous structure can be suitably used as a bonding layer. Note that another plating layer or the like may be appropriately formed under the binary alloy plating layer 4.

  Hereinafter, although the metal material joining method of the present invention will be further described in Examples, the present invention is not limited to these Examples.

Example 1
In order to obtain samples for various evaluations (SEM observation and ICP-MS analysis), a 20 mm square silicon substrate on which a platinum sputtered film was formed was subjected to Au—Ag alloy plating. The composition of the plating bath was HAuCl ₄ · 4H ₂ O: 1 mM, AgNO ₃ : 2 mM, Thiourea (thiourea): 0.2 M, H ₂ SO ₄ : 0.01 M, and a voltage of 0.7 V for 30 minutes. Processed.

Next, a deporous corrosion was applied to the Au—Ag alloy plating layer (Au: 50 mass%, Ag: 50 mass%) to form a nanoporous metal layer, and an evaluation sample 1 was obtained. Specifically, after polishing the surface of the Au—Ag alloy plating layer with abrasive paper, it is immersed in nitric acid (HNO ₃ : H ₂ O = 2: 1) with application of ultrasonic waves to etch Ag near the surface. Thus, an Au—Ag alloy plating layer having a nanoporous structure mainly composed of gold (Au) on the surface was obtained. Here, the immersion time was 30 seconds, and the sample after immersion was washed with pure water.

  FIG. 3 shows a scanning electron microscope (SEM) photograph of the surface of the Au—Ag alloy plating layer after the immersion treatment. The surface of the Au-Ag alloy plating layer after the immersion treatment (decomponent corrosion) has a nanoporous structure in which metal nanoparticles are arranged three-dimensionally, and the average particle diameter of the metal nanoparticles is about It was 10 nm. The scanning electron microscope used was an ultra-high resolution analytical scanning electron microscope S-4800 manufactured by Hitachi High-Tech.

  The Ag content in the vicinity of the Au—Ag alloy plating layer surface was measured by ICP-MS analysis, and the obtained value is shown in FIG. In addition, the value of Ag content rate in the vicinity of the Au-Ag alloy plating layer surface which has not performed immersion treatment (decomponent corrosion) is also shown as a comparison. From the results, it can be seen that the Ag content in the vicinity of the Au—Ag alloy plating layer surface is reduced by the immersion treatment (decomponent corrosion). This means that the surface of the Au—Ag alloy plating layer is composed of metal nanoparticles mainly composed of Au.

In order to obtain a sample for a joining experiment, Au—Ag alloy plating treatment was performed on the surface of a copper base material (φ10 mm, 5 mm thick cylindrical shape) having a gold plating layer. The composition of the plating bath is the same as in the case of preparing the evaluation sample (HAuCl ₄ .4H ₂ O: 1 mM, AgNO ₃ : 2 mM, Thiourea (thiourea): 0.2M, H ₂ SO ₄ : 0.01M). And the treatment for 30 minutes was performed at a voltage of 0.7V.

  The same decomponent corrosion as in the case of preparing the evaluation sample was applied to the Au—Ag alloy plating layer (Au: 50 mass%, Ag: 50 mass%), and the joining test piece 1 was prepared. A cylindrical copper material having a diameter of 3 mm and a thickness of 2 mm was stacked on the Au—Ag alloy plating layer formed on the surface of the test piece, and a joining test was performed (joining temperature 350 ° C., joining time: 30 minutes, joining Pressure: 20 MPa, atmosphere: nitrogen). Note that immediately after the test, the test piece was taken out of the apparatus and air-cooled.

  About the joining joint 1 obtained by the joining test, the shear test (shear rate 1.0mm / min, shear height 200micrometer) was done using the bond tester, and joining strength was calculated | required. The obtained shear strength is shown in FIG. Three bonded joints were prepared, and a shear test was performed on each bonded joint to obtain an average value.

<< Example 2 >>
An evaluation sample 2 was obtained in the same manner as in Example 1 except that the immersion time in nitric acid (HNO ₃ : H ₂ O = 2: 1) was 3600 seconds. A scanning electron microscope (SEM) photograph of the surface of the Au—Ag alloy plating layer of the sample 2 for evaluation is shown in FIG. The surface of the Au—Ag alloy plating layer has a nanoporous structure in which metal nanoparticles are arranged three-dimensionally, and the average particle diameter of the metal nanoparticles is about 50 nm. When the immersion time is 30 seconds, the average particle diameter is about 10 nm, and it can be seen that the average particle diameter of the metal nanoparticles can be controlled by the immersion time.

FIG. 4 shows the Ag content in the vicinity of the Au—Ag alloy plating layer surface in the sample 2 for evaluation.

Example 3
An evaluation sample 3 and a joint joint 3 were obtained in the same manner as in Example 1 except that annealing treatment (temperature: 50 ° C., time: 60 minutes, atmosphere: nitrogen) was performed before the decomponent corrosion. A scanning electron microscope (SEM) photograph of the surface of the Au—Ag alloy plating layer of the sample 3 for evaluation is shown in FIG. The surface of the Au—Ag alloy plating layer has a nanoporous structure in which metal nanoparticles are arranged three-dimensionally, and the average particle diameter of the metal nanoparticles is about 20 nm.

FIG. 4 shows the Ag content in the vicinity of the Au—Ag alloy plating layer surface in the sample 3 for evaluation.

  The shear strength of the joint joint 3 obtained in the same manner as in Example 1 is shown in FIG. The shear strength of the joint joint 3 obtained by performing the annealing treatment at 50 ° C. is higher than the shear strength of the joint joint 1, and it can be seen that the annealing treatment contributes to the improvement of the shear strength. This is considered to be because the average particle diameter of the metal nanoparticles on the surface of the Au—Ag alloy plating layer became a suitable value by the annealing treatment.

Example 4
An evaluation sample 4 and a joint joint 4 were obtained in the same manner as in Example 1 except that annealing treatment (temperature: 150 ° C., time: 60 minutes, atmosphere: nitrogen) was performed before the decomponent corrosion. FIG. 8 shows a scanning electron microscope (SEM) photograph of the surface of the Au—Ag alloy plating layer of the sample 4 for evaluation. The surface of the Au—Ag alloy plating layer has a nanoporous structure in which metal nanoparticles are arranged three-dimensionally, and the average particle diameter of the metal nanoparticles is about 50 nm.

  FIG. 4 shows the Ag content in the vicinity of the Au—Ag alloy plating layer surface in the sample 4 for evaluation.

  The shear strength of the joint joint 4 obtained in the same manner as in Example 1 is shown in FIG. Although the shear strength of the joint joint 4 obtained by performing the annealing treatment at 150 ° C. is higher than the shear strength of the joint joint 1, it is lower than the shear strength of the joint joint 3 obtained by performing the annealing treatment at 50 ° C. It is a value. The result shows that the annealing treatment contributes to the improvement of the shear strength, but the contribution depends on the treatment temperature. When the annealing treatment is as high as 150 ° C., the rearrangement of atoms proceeds too much, and as a result, the average particle size of the metal nanoparticles on the Au—Ag alloy plating layer surface becomes too large. This seems to be the reason why the strength was lower than 3.

Example 5
An evaluation sample 5 was obtained in the same manner as in Example 1 except that an annealing treatment (temperature: 100 ° C., time: 60 minutes, atmosphere: nitrogen) was performed before decomponent corrosion. FIG. 4 shows the Ag content in the vicinity of the Au—Ag alloy plating layer surface in the sample 5 for evaluation.

  FIG. 4 shows that the Ag content in the vicinity of the Au—Ag alloy plating layer surface decreases as the annealing temperature increases. This result means that the composition of the metal nanoparticles formed in the vicinity of the Au—Ag alloy plating layer surface can be controlled by the annealing treatment temperature.

1 ... Metal member for joining metal materials,
2 ... Metal substrate,
4 ... Binary alloy plating layer,
6: Nanoporous structure region.

Claims (9)

A first step of forming a plating layer on a bonded surface of the first bonded material and / or the second bonded material;
A second step in which the plating layer is subjected to decomponent corrosion treatment to form a nanoporous metal layer;
While heating the nanoporous metal layer to 50 to 400 ° C. in a state where the first bonded material and the second bonded material are brought into contact with each other through the nanoporous metal layer, Including a third step of pressurizing the first material to be joined and the second material to be joined,
A metal material joining method characterized by the above. Furthermore, between the first step and the second step, having a structure adjustment step of applying an annealing treatment to the plating layer,
The metal material joining method according to claim 1. Setting the temperature of the annealing treatment to 50 to 150 ° C .;
The metal material joining method according to claim 2. The nanoporous metal layer includes metal nanoparticles having a three-dimensionally arranged average particle diameter of 5 to 500 nm;
The method for joining metal materials according to any one of claims 1 to 3. The plating layer is a binary alloy;
The metal material joining method according to any one of claims 1 to 4. The binary alloy is an Au-Ag alloy;
The metal material joining method according to claim 5. The first material to be joined and / or the second material to be joined is a copper material,
The metal material joining method according to any one of claims 1 to 6. Having a binary alloy plating layer on at least a portion of the metal substrate;
At least the vicinity of the surface of the binary alloy plating layer has a nanoporous structure containing metal nanoparticles having an average particle size of 5 to 500 nm arranged three-dimensionally;
A metal member for joining a metal material. The binary alloy plating layer is an Au-Ag alloy plating layer;
The metal member for joining a metal material according to claim 8.