Manufacturing method of aluminum-based brazing materials

Abstract

The productivity of an aluminum-based brazing material is poor. This method for producing an aluminum-based brazing material is characterized by including: a step for producing a plating solution containing an Al ion and a Ti ion; and a step for immersing a substrate and electrodes in the plating solution to apply an electric current, thereby forming a first metal layer which comprises 0.01 to 10 at%, inclusive, of Ti and a remainder comprising Al and unavoidable impurities on the substrate.

Description

[Technical Field]

[0001] This invention relates to a method for producing aluminum-based brazing materials. [Background technology]

[0002] One widely used method for joining ceramics and metals is brazing with brazing materials. Brazing materials are known to be mainly composed of silver (Ag), with copper (Cu) or tin (Sn) added to lower the melting point, such as in Ag-Cu-Sn systems. However, these materials cannot bond to ceramics as they are, so those containing about 2 at% titanium (Ti) have been mainly used to activate the bonding interface with ceramics and to obtain bonding strength. However, because they contain a large amount of Ag and Ti, the brazing materials are very expensive, resulting in a high cost for joining. In recent years, various new brazing materials have been investigated as a solution to this problem. For example, Patent Document 1 discloses an Al-Si-Ti ternary alloy brazing material characterized by containing 0.1 to 2.0 wt% Ti, 0.07 to 12.0 wt% silicon (Si), and the remainder consisting of aluminum (Al) and unavoidable impurities. According to Patent Document 1, it is described that a highly reliable bond can be obtained by utilizing the antioxidant effect of Si on Al and the oxide film activating effect of Ti as a brazing material using an inexpensive Al alloy. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-294890 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, Patent Document 1 does not specifically disclose a method for manufacturing aluminum-based brazing materials. In order to reduce the cost of brazing materials, in addition to using low-cost metals, one of the challenges is to apply a manufacturing method that is cost-effective and highly productive. Furthermore, in order to obtain high-quality aluminum-based brazing materials, it is important to realize a configuration in which elements such as Ti selected for a predetermined purpose function effectively. In view of the above problems, the object of the present invention is a method for manufacturing aluminum-based brazing materials that is suitable for obtaining high-quality aluminum-based brazing materials and is highly productive. of It is about providing. [Means for solving the problem]

[0005] This invention One aspect This involves the process of preparing a plating solution containing Al ions and Ti ions, A step of immersing the substrate and electrodes in the aforementioned plating solution and applying an electric current to form a first metal layer on the substrate consisting of 0.01 at% to 10 at% Ti, with the remainder being Al and unavoidable impurities. to have The process of preparing the plating solution involves one of the following: mixing titanium tetrachloride with a plating solution containing Al ions; immersing metallic titanium in the plating solution containing Al ions; or immersing metallic titanium and a metal plate paired with the metallic titanium in the plating solution containing Al ions, and passing a direct current through the metallic titanium as the anode and the paired metal plate as the cathode, thereby incorporating Ti as an ion into the plating solution containing Al ions. This is a method for manufacturing aluminum-based brazing materials characterized by [the following]. [Effects of the Invention]

[0009] The present invention provides a suitable and highly productive method for producing high-quality aluminum-based brazing materials. of We can provide it. [Brief explanation of the drawing]

[0010] [Figure 1] (a) Cross-sectional view of an aluminum brazing material observed using a scanning electron microscope, (b) Distribution map of Ti compositional analysis, and (c) Line analysis results of Al, Ti, C, and O compositional analysis. [Figure 2] (a) Cross-sectional view of an aluminum brazing material observed using a transmission electron microscope, and (b-1) Distribution map of Al, (b-2) Ti, and (b-3) O obtained through compositional analysis. [Figure 3](a) Cross-sectional view observed using a transmission electron microscope at the bonding interface of a ceramic composite substrate, and (b) Line analysis results of compositional analysis of Al, Si, N, and O. [Figure 4] Distribution map of Al, Ti, and N obtained by compositional analysis of the bonding interface of a ceramic composite substrate using a transmission electron microscope. [Figure 5] External view of a ceramic composite substrate (ceramics / Al-Ti / Zn / Ni plating film / Cu bond). [Figure 6] External view photograph of a ceramic composite substrate (ceramics / Al-Ti bond). [Figure 7] Cross-sectional TEM image of aluminum-based brazing material [Figure 8] Electron diffraction pattern of aluminum-based brazing material [Figure 9] External view of a ceramic composite substrate (ceramics / Al-Ti bond, 10mm square). [Modes for carrying out the invention]

[0011] One of the features of the present invention is that an aluminum-based brazing material (Al-Ti brazing material) can be obtained by a manufacturing method (electrolytic method, electroplating) that comprises the steps of: preparing a plating solution containing Al ions and Ti ions; and immersing a substrate and an electrode in the plating solution and applying an electric current to form a first metal layer on the substrate consisting of 0.01 at% to 10 at% Ti, with the remainder being Al and unavoidable impurities. Both Al and Ti are electrochemically active, and their reduction and deposition potentials are relatively close. Therefore, in conventional manufacturing methods such as casting, mixing, and rolling, they easily oxidize and lose their activity. However, by manufacturing using a non-aqueous plating solution and electroplating, both metals can be deposited simultaneously. When observed at a microscopic level, the brazing material can be provided with a composition and structure that cannot be obtained by these conventional methods, in which Ti is uniformly distributed within Al, and the thickness is uniformly controlled in a foil shape. In particular, the Ti obtained in a form encompassed by Al can be obtained as a metal while remaining in an active state, so the Ti functions effectively. This invention achieves such high quality through the simple electroplating method described above, resulting in excellent productivity. Furthermore, because the main component of the brazing material is low-cost aluminum, it contributes to cost reduction. In this invention, the brazing material is defined as a metallic material that can be bonded to both ceramics and metals. Bonding in this case includes not only the simple adhesion of the brazing material, but also a technique called metallization, since the brazing material itself is a metal.

[0012] Another feature is that a ceramic composite substrate can be fabricated by the action of Ti by placing the first metal layer obtained in this way onto a ceramic substrate and performing bonding. Because the main component is Al, which has a relatively low melting point, there is little thermal strain at the bonding interface, and furthermore, because Ti is uniformly distributed throughout the brazing material, there is little variation in bonding strength, and a ceramic composite substrate with high bonding reliability can be provided. In addition, a multilayer ceramic composite substrate can be obtained by going through the process of placing and bonding the first metal layer onto a ceramic substrate and the process of stacking and bonding at least a second metal layer. This second metal layer has a different composition from the first metal layer. Since the first metal layer is already a layer mainly composed of Al, bonding the first metal layer and the second metal layer can be easily performed at an even lower temperature, resulting in reduced bonding costs and reduced thermal strain and stress at the bonding interface, i.e., high bonding reliability.

[0013] The details of the manufacturing method for aluminum-based brazing materials are shown below as an implementation method. (Manufacturing method for aluminum-based brazing materials) The first metal layer of the aluminum-based brazing material of the present invention is manufactured by electrolytic method (electroplating). The first metal layer is a metal layer whose main component is Al, and even when observed under a microscopic field of view, Ti is uniformly distributed throughout it. Therefore, the first metal layer of the aluminum-based brazing material may be referred to as Al-Ti brazing material or Al-Ti below. Examples of plating solutions include a plating solution in which an aluminum salt is dissolved in a solvent such as dialkylsulfone or toluene, which is capable of depositing (plating) aluminum at low temperatures of 120°C or below; a plating solution consisting of an aluminum salt and an imidazolium salt; and a plating solution in which an aluminum salt is melted at high temperatures of 200°C or above, which is capable of depositing aluminum at high temperatures of 200°C or above. After preparing the plating solution containing the above-mentioned Al ions, Ti ions are incorporated into the plating solution as ions by, for example, (a) mixing a metal salt such as titanium tetrachloride, (b) dipping metallic titanium in the solution, or (c) dipping metallic titanium and another pair of metal plates in the solution and passing a direct current with the metallic titanium as the anode and the pair of metal plates as the cathode to dissolve the metallic titanium. The amount of Ti contained in the plating solution is determined according to the amount of Ti to be contained in the Al-Ti brazing material. For example, when attempting to obtain an Al-Ti brazing material with Ti = 0.01 to 10 at%, the amount of Ti eluted into the plating solution may be Ti = 0.005 to 5 at%. The amount of Ti referred to here means the ratio with respect to the amount of substance of Al and Ti in the Al-Ti brazing material or in the plating solution. In a plating bath filled with the above-mentioned plating solution, a cathode (substrate) and an anode electrode are prepared, and a direct current is passed between the two electrodes to form a first metal layer (Al-Ti) consisting of Ti of 0.01 at% or more and 10 at% or less, the balance being Al and inevitable impurities, on the substrate. The substrate on which Al-Ti is formed can be used as it is as a product (integrated with Al-Ti), or the Al-Ti part can be peeled off from the substrate and used as Al-Ti alone. At this time, aluminum or titanium is used for the anode electrode. For the shape, a plate shape, a foil shape, or a case filled with a ball shape, a pellet shape, etc. in the case of an insoluble material can be used, and not only one kind of metal but also a plurality of metals can be arranged and used. Since the metal of the anode plays a role of replenishing the metal ions consumed at the cathode by dissolving upon energization, for example, when both aluminum and titanium are installed as anodes, the Al ions and Ti ions in the solution consumed by the production of Al-Ti can be replenished simultaneously, which is convenient.

[0014] In addition, for the base material, various metal materials can be used, such as aluminum and titanium, according to the intended product form. For example, when it is desired to use in an integrated form of aluminum, zinc, nickel, copper, etc. and Al-Ti, aluminum foil, zinc foil, nickel plate, copper plate, copper plate plated with nickel, etc. can be directly used as the cathode. Alternatively, when it is desired to obtain Al-Ti alone, titanium, stainless steel, etc. can be used as the cathode as a substrate that is easy to peel off. The shape of these base materials may be in the form of a wire, rod, powder, long plate or a coil wound with a foil, or a sheet of any size, or a cylindrical shape made of a material that is easy to peel off when continuously peeled to obtain Al-Ti alone. The configuration using a base material wound in a coil shape enables continuous processing in which the base material is unwound from the coil and immersed in the plating solution, and the aluminum-based brazing material on which the first metal layer is formed is wound in a coil shape, thus contributing to an improvement in productivity.

[0015] When manufacturing Al-Ti, the current density of the current flowing through the electrode is adjusted according to the thickness, manufacturing speed, and appearance of the desired Al-Ti. For example, the current density is generally about 80 - 600 mA / cm 2 ². Regarding the thickness of the Al-Ti to be manufactured, it can be controlled not only by the current density but also by the energization time. Considering the use as a brazing material, the thickness of Al-Ti is appropriately about 0.5 - 100 μm, and the current density and time can be adjusted according to these requirements.

[0016] The Al-Ti deposited on the base material can then be used as a product by washing the plating solution and drying it as it is, or it can be used as a product after heat treatment for conditioning (removing residual stress, removing the cleaning solution, etc.) and acid / alkali cleaning for removing the surface oxide film. By the above method, an aluminum-based brazing material useful for manufacturing a ceramic composite substrate can be obtained.

[0017] (Physical properties of aluminum-based brazing material) Figure 1 shows the crystalline structure and compositional distribution of the aluminum brazing material obtained by the above manufacturing method, observed from a cross-section. The observation was performed using a scanning electron microscope (JEOL Ltd., JSM-7900F) at an acceleration voltage of 5kV and a field of view of 3000x magnification. As shown in Figure 1(a), the crystalline structure of the aluminum brazing material at an acceleration voltage of 5kV and 3000x magnification is fine columnar crystals. The crystal size changes depending on the Ti content, with the columnar crystals becoming finer as the Ti content increases. Furthermore, the elemental mapping results in Figure 1(b) show that Ti is uniformly distributed throughout, and the line analysis results in Figure 1(c) confirm that it is in an active state and not oxidized. Furthermore, the results of observations regarding the state of Ti are shown in Figure 2. The observations were performed using a transmission electron microscope (JEM-2800, JEOL Corporation) with an acceleration voltage of 200 kV and a field of view of 1 million times magnification. From the compositional distribution of Ti in Figure 2(b-2) relative to the particle dimensions in Figure 2(a), it was confirmed that the size of Ti was too small to be detected as a particle under these observation conditions, and that it was in an active state without oxidation, based on its abundance ratio with oxygen. In addition, observations and compositional analysis of grain boundaries and within grains were performed in a separate field of view (Figure 7). The Ti crystal grains were too small to be detected (TEM image in Figure 7), and it was confirmed that it was contained in a ratio of 1.7 to 2.0 at%, and was uniformly distributed without being concentrated at grain boundaries or within grains (analysis results for locations in Figure 7(i) to (iii)). Furthermore, from the comparison of compositional ratios, since the amount of Ti is greater than that of oxygen (O), it is considered that Ti is distributed in an active state, maintaining its metallic properties without oxidation. Furthermore, when the crystallinity of this sample was confirmed by electron diffraction (Figure 8), the only diffraction peaks obtained were those attributed to Al. This suggests that Ti exists in the Al in a state too fine to be detected by this method. Thus, a state in which crystal grains are absent or present in an extremely fine state of nanoscale or smaller, and which is dispersed throughout the entire bulk of Al without being concentrated within grains or at grain boundaries, is called a uniform distribution, and this manufacturing method can be used to obtain aluminum brazing material with a uniform distribution of Ti. The melting point of Al-Ti brazing material is approximately the same as that of pure Al, around 660°C. The composition consists of 80 mass% or more Al, and other components include Ti and components derived from the plating solution. When prepared from the dimethyl sulfone-based plating solution mentioned above, the content varies depending on the manufacturing conditions, but it contains carbon (C), oxygen, sulfur (S), and chlorine (Cl). Furthermore, the amount of Ti contained in Al-Ti is preferably 0.01 to 10 at%. Since Ti plays a role in enabling Al to wet and spread on ceramics, a higher content is desirable, but if it exceeds 10 at%, the Al-Ti brazing material itself becomes brittle and difficult to use as a brazing material. Therefore, the aluminum-based brazing material obtained by the manufacturing method of the present invention consists of 0.01 at% to 10 at% Ti, with the remainder being Al and unavoidable impurities, and has a first metal layer in which the Ti is uniformly distributed.

[0018] (Method for manufacturing ceramic composite substrates) Next, the bonding of the manufactured aluminum-based brazing material to the ceramic substrate will be described. Various ceramic substrates can be used for bonding, as long as the first metal layer can be wetted and spread in an inert atmosphere, such as silicon nitride. The first metal layer (Al-Ti) of the aluminum-based brazing material manufactured by the method described above is placed on the ceramic substrate and the bonding is performed. For example, the Al-Ti is melted and wetted and spread on the ceramic substrate by heating in an inert atmosphere such as a vacuum atmosphere, nitrogen gas atmosphere, or argon gas atmosphere at a temperature of 660°C to 800°C for a holding time of 1 to 120 minutes. The heating temperature should be set to a temperature above the melting point (approximately 660°C) when using Al-Ti alone, and above the eutectic point when it is integrated with other metals. After that, when cooled, the Al-Ti solidifies, and a ceramic / Al-Ti bonded body, i.e., a ceramic composite substrate, is obtained in which the ceramic substrate and Al-Ti are integrated. At this time, weights or the like may be placed on top of the Al-Ti to position it and suppress void formation at the ceramic-Al-Ti interface. For example, a boron nitride (BN) plate, which is difficult to bond with Al-Ti, can be placed on top of it, and weights or the like can be placed on top of it. Regarding the surface composition of the ceramics, it is desirable that they be in a clean state, free from residual components such as oil that would impair wettability with Al-Ti. Methods for removing these components include washing, degreasing, high-temperature heat treatment, and surface polishing. Furthermore, there are no particular restrictions on the surface shape; for example, any surface with an arithmetic mean roughness Ra of 0.03 μm or higher should be used. It is desirable to remove the oxide film from the surface of Al-Ti before use. Common removal methods include cleaning with acid or alkali, heat treatment in a reducing atmosphere furnace, and surface grinding. For example, in actual manufacturing, a cleaning tank for cleaning with acid or alkali can be provided during the manufacturing process of the above-mentioned aluminum brazing material, or the manufactured aluminum brazing material coils can be heat-treated in a hydrogen reducing atmosphere furnace, or the surface can be ground using brushes or abrasives.

[0019] (Method for manufacturing multilayer ceramic composite substrates) Furthermore, it is possible to fabricate multilayer ceramic composite substrates using aluminum-based brazing materials. A multilayer structure is a structure having at least a second metal layer of a different composition, or a structure in which more metal layers are laminated and joined, or a structure in which the same or different types of ceramic layers are laminated and joined. The following explanation will use an example having at least a second metal layer. The term "metal layer" here is not limited to film-like or plate-like materials, but also includes bulk materials such as structures. For example, if aluminum fins are used as the metal layer, a heat dissipation substrate can be obtained, and if copper plates are used as the metal layer, a circuit board can be obtained in the same way. When obtaining these ceramic composite substrates, depending on the required properties and mechanical strength, the first metal layer can be joined using general adhesives, soldering, brazing, etc. Alternatively, the second metal layer itself can be used as the brazing material. Since the ceramic substrate is already firmly bonded to the first metal layer, which is Al-Ti, the bondability of the second metal layer to be joined here should be considered. Therefore, when joining aluminum and copper as described above, for example, it is possible to use an Al-Si brazing material containing silicon (Si), an aluminum solder mainly composed of zinc, or a combination of aluminum solder and copper solder as the second metal layer. Furthermore, for these joining processes, a material with a lower melting point than conventional Ag-based brazing materials can be used as the brazing material (second metal layer). Specifically, it is possible to perform the joining at a melting point below or even lower than the melting point of the first metal layer (Al-Ti) (approximately 660°C), and below the eutectic point with Al-Ti. In this way, it becomes possible to fabricate ceramic composite substrates using Al-Ti.

[0020] (Physical properties of ceramic composite substrates) The ceramic composite substrate obtained by the above method will now be described. When conventional Ag-Ti brazing materials containing Ti are used, it is known that a layer of titanium nitride (TiN) with a thickness of 1 to 2 μm is formed at the interface with the ceramics. Since TiN has poor thermal conductivity, the thermal conductivity of ceramic composite substrates made using Ag-Ti brazing materials decreases at their bonding interface. In contrast, when aluminum brazing materials are used, no such layer is observed, and instead, a layer mainly composed of Al and elements contained in the ceramics is formed. The main component of this layer is Al, which has good thermal conductivity, and since its thickness is also thin, the thermal conductivity at the bonding interface of the ceramic composite substrate does not decrease, and good physical properties can be achieved. Furthermore, ceramic composite substrates formed by joining the aforementioned ceramic substrate and the first metal layer using an aluminum-based brazing material, as well as multilayer ceramic composite substrates formed by joining the first metal layer and at least the second metal layer, can be manufactured at low temperatures of 660°C or below. Compared to conventional Ag-Ti-based brazing materials, they exhibit less stress concentration and thermal strain at the bonding interface, resulting in superior bonding reliability. Moreover, changes in the crystal structure due to heat are suppressed, and there is virtually no change (degradation) in the physical properties of each material before and after bonding. Therefore, by using these manufacturing methods, joining methods, and brazing materials, it becomes possible to manufacture and provide ceramic composite substrates with superior reliability and performance compared to conventional methods. [Examples]

[0021] The following are specific examples. (Example 1) (Preparation of aluminum-based brazing materials) Ten moles of dimethyl sulfone (DMSO2) were heated and melted at 110°C. Three moles of anhydrous aluminum chloride (AlCl3) and ten moles of ammonium chloride were mixed in and stirred to prepare a homogeneous plating solution. The ammonium chloride used was dried in a vacuum dryer at 100°C for 12 hours. Next, two titanium plates were immersed in the prepared plating solution, with the plates serving as the cathode and anode electrodes, respectively. The solution temperature was 85°C and the plating current was 50 mA / cm².2 The system was energized at a current density of 30 minutes to dissolve Ti in the plating solution, creating an Al-Ti plating solution containing Ti ions. Analysis of the prepared Al-Ti plating solution using ICP revealed that the Ti concentration was 0.8 at% relative to the total amount of Al and Ti contained in the plating solution. Next, the Al plate and Ti plate were immersed in the prepared Al-Ti plating solution, with the anode and cathode respectively, and a 50 mA / cm² plating rate was applied. 2 A DC current was passed through the Ti plate at the specified current density for 36 minutes to form an Al-Ti plating film. After the current was removed, the cathode electrode was washed with water and dried, and the plating film was peeled off from the Ti plate to obtain an aluminum-based brazing material. The obtained Al-Ti brazing material had a thickness of 16 μm, and analysis by ICP revealed that the Ti concentration in the aluminum-based brazing material was 2 at%. Furthermore, the liquid temperature when dissolving Ti in the plating solution was set to 95°C, and the current density to 100 mA / cm². 2 The liquid temperature for forming Al-Ti on the cathode was set to 90°C and the mA / cm² to 100 mA / cm². 2 Similarly, Al-Ti could be obtained. The Ti concentration in the Al-Ti obtained in this case depended on the amount of Ti dissolved in the solution; for example, when the amount of Ti in the solution was 1.7 at%, the amount of Ti in the Al-Ti was 3.8 at%. The Al-Ti brazing material prepared in this manner was surface-treated by immersing it in a 10-fold diluted acidic aluminum surface treatment agent (AL50, manufactured by World Metal Co., Ltd.) at room temperature for 50 seconds to remove the surface oxide film. After treatment, it was washed with running water and air-dried. The oxygen concentration on the surface before and after treatment was measured and compared using energy-dispersive spectroscopy (OXFORD Energy250) at an accelerating voltage of 5kV and a field of view of 1000x magnification, confirming a reduction from 2.9 at% to 0.8 at%. Furthermore, to remove the surface oxide film of the fabricated aluminum brazing material, we used an alkaline aluminum surface treatment agent (AL20, manufactured by World Metal Co., Ltd.) and treated it by immersing it in the solution at room temperature for 2 minutes. We confirmed that the oxygen concentration on the surface was similarly reduced to 1.1 at%.

[0022] (Joining ceramics and aluminum-based brazing material) For the ceramics, silicon nitride (hereinafter referred to as SiN) measuring 10 mm x 10 mm and 0.3 mm thick was used. Before joining, the surface of the SiN was polished smooth using a diamond slurry to a clean state. The arithmetic mean roughness Ra of the polished SiN was 0.08 μm. The aluminum-based brazing material prepared above was cut to a size of approximately 8 mm x 8 mm and placed on top of the polished SiN, and then left to stand in an atmospheric furnace. 1 × 10 -3 A ceramic / Al-Ti bond (ceramic composite substrate) was obtained by firing in a vacuum atmosphere below Pa under the following conditions: heating rate of 10°C / min, cooling rate of -10°C / min, holding temperature of 735°C, and holding time of 30 minutes. The obtained ceramic composite substrate is shown in Figure 9. The bonding interface between the ceramics and Al-Ti in the ceramics / Al-Ti bond was observed from a cross-section. The results are shown in Figure 3(a). A transmission electron microscope (JEM-2800, JEOL) was used for the observation. It was confirmed that no TiN layer, as is the case when conventional Ag-Ti brazing materials are used, was formed at the bonding interface, and instead a layer of Al, N, O with a thickness of several tens of nanometers was formed (Figure 3(b)). Based on the composition ratio of each component, the layer of Al, N, O is mainly composed of Al and is not a simple oxide layer like alumina. From these findings, it can be inferred that the interface configuration has superior thermal conductivity compared to the case when conventional Ag-Ti brazing materials are used, which form a TiN layer with poor thermal conductivity. Furthermore, it was confirmed that the thickness of this Al, N, O layer increases with higher holding temperatures and longer holding times during firing. On the other hand, it was confirmed that Ti was not concentrated at the interface. The composition mapping observation results in the macro field of view shown in Figure 3 are shown in Figure 4. It was confirmed that the Ti in the aluminum-based brazing material placed on the SiN aggregated after heating and melting, forming an alloy of Al and Ti, and was scattered within the bulk of Al. Furthermore, such ceramic composite substrates could be similarly fabricated using large-sized SiN of 190 mm × 130 mm and a thickness of 0.3 mm. A photograph of the appearance of the fabricated substrate is shown in Figure 6.

[0023] (Fabrication of circuit boards (multilayer ceramic composite substrates)) A pure zinc (Zn) foil (manufactured by Nilaco) was placed as a second metal layer on top of the first metal layer of the fabricated ceramics / Al-Ti bond, and then a Cu plate with a 20 μm thick Ni plating film was placed on top of that, resulting in a stacked structure in the order of (ceramics / Al-Ti bond) / Zn / Ni plating film / Cu plate. This was then placed in an atmospheric furnace and heated under argon (Ar) atmosphere conditions of heating rate 10°C / min, cooling rate -10°C / min, holding temperature 430°C, and holding time 5 minutes to obtain a Cu-bonded circuit board (multilayer ceramic composite substrate). The obtained ceramic composite substrate is shown in Figure 5. The bonded Cu plate was firmly bonded to the ceramics / Al-Ti bond and had sufficient strength to withstand practical use. This was verified by the fact that the shear strength measurement results, performed using a bond tester 4000plus (Nordson Advanced Technology) at a test speed of 100 μm / s, were 80 MPa or higher, and by the fact that no delamination occurred even after more than 250 cycles of measurement in a thermal cycle test performed under conditions of -40°C to 160°C. Furthermore, in Example 1-2, which is a partial modification of Example 1, a Cu-laminated circuit board was also obtained by using Al foil instead of Ni and laminating in the order of (ceramics / Al-Ti bond) / Zn / Al / Cu plate.

[0024] Furthermore, in Example 1-3, which is a modified version of Example 1, a commercially available aluminum solder (T235, manufactured by Almit Co., Ltd.) was placed as a second metal layer on the Al-Ti side of the ceramic composite substrate, replacing the Zn and Ni used in Example 1. A Cu plate was then placed on top of this, and the circuit board was heated at 250°C in an atmospheric environment. This also yielded a Cu-bonded circuit board with sufficient strength, similar to that described above.

[0025] Furthermore, in Example 1-4, which is a modified version of Example 1, an Al-Si alloy foil was placed as at least a second metal layer on the Al-Ti side of the first metal layer as a multilayer ceramic composite substrate, and an Al plate was placed on top of that. The substrate was then left to stand in an atmospheric furnace and heated under the conditions of a vacuum atmosphere, a heating rate of 10°C / min, a cooling rate of -10°C / min, a holding temperature of 590°C, and a holding time of 30 minutes to obtain an Al-bonded circuit board. The Al plate was firmly bonded to the ceramic composite substrate and had sufficient strength to withstand practical use.

[0026] Furthermore, in Example 1-5, which is a modified version of Example 1, Al-Ti is arranged on one side of the SiN plate, and Ag-Cu-In-Ti brazing material and a Cu plate are arranged on the other side in that order, resulting in 1 × 10 -3 The ceramic substrate was heated in a vacuum atmosphere below Pa under the following conditions: heating rate of 10°C / min, cooling rate of -10°C / min, holding temperature of 830°C, and holding time of 30 minutes. This resulted in obtaining a circuit board (multilayer ceramic composite substrate) with different metal types on both sides of the ceramic substrate, namely Al-Ti on one side and Cu on the other.

[0027] Using the ceramics / Al-Ti bond prepared in Example 1, an Al-Ti / ceramics / Al-Ti bond was created by sandwiching a ceramic plate between the first metal layers and bonding Al-Ti to the other side as well. This resulted in a stacked structure consisting of Al plate / Zn / (Al-Ti / ceramics / Al-Ti bond) / Zn / Al foil / Cu plate, and this structure was measured in 1 × 10⁻¹⁰⁶⁻¹⁰ -3 The ceramic composite substrate was heated in a vacuum atmosphere below Pa under the following conditions: heating rate of 10°C / min, cooling rate of -10°C / min, holding temperature of 430°C, and holding time of 5 minutes. This resulted in obtaining a circuit board (multilayer ceramic composite substrate) with different metal types on both sides of the ceramic composite substrate. Because it was heated at a relatively low temperature, thermal stress was low, and a circuit board without warping was obtained. This makes it possible to obtain an electrical circuit board with an aluminum heat sink (such as a heat sink) on one side and an electronic circuit formed on the other. Furthermore, bonding in the multilayer structure can be performed in a non-oxidizing atmosphere such as Ar, in addition to a vacuum atmosphere, as long as it does not affect the ceramic composite substrate.

[0028] (Example 2) In the above Example 1, a ceramic composite substrate could also be obtained by using aluminum nitride instead of silicon nitride for the ceramics. Further, as Example 2-2 with a partial modification of Example 2, a ceramic composite substrate could also be obtained by using aluminum oxide. Further, as Example 2-3 with a partial modification of Example 2, a ceramic composite substrate could also be obtained by performing ultrasonic cleaning in pure water instead of polishing for the pre-bonding treatment. Further, as Example 2-4 with a partial modification of Example 2, a ceramic composite substrate could also be obtained by performing wiping cleaning with acetone, which is an organic solvent, instead of polishing for the pre-bonding treatment. Further, as Example 2-5 with a partial modification of Example 2, a ceramic composite substrate could also be obtained by performing wiping cleaning with ethanol, which is an organic solvent, instead of polishing for the pre-bonding treatment.

[0029] (Example 3) In Example 1, an Al-Ti plating solution with a Ti concentration of 0.1 at% with respect to the total amount of Al and Ti contained in the plating solution was used, and a direct current was passed at a current density of 200 mA / cm 2 for 5 minutes, and in other respects, the same procedure as described above was followed to obtain an Al-Ti brazing filler metal. The obtained Al-Ti brazing filler metal had a thickness of 5 μm, and when analyzed by ICP, the Ti concentration in the aluminum-based brazing filler metal was 0.2 at%. The obtained Al-Ti brazing filler metal could be joined to various ceramics, and it was also possible to fabricate a ceramic composite substrate.

[0030] (Example 4) In Example 1, an Al-Ti plating solution with a Ti concentration of 2.7 at% with respect to the total amount of Al and Ti contained in the plating solution was used, and 100 mA / cm 2An Al-Ti brazing material was obtained by applying a DC current at the specified current density for 12 minutes, and otherwise proceeding as described above. The obtained Al-Ti brazing material had a thickness of 10 μm, and analysis by ICP revealed that the Ti concentration in the aluminum-based brazing material was 7 at%. The obtained Al-Ti brazing material could be bonded to various ceramics, and it was also possible to fabricate ceramic composite substrates.

[0031] (Example 5) In Example 1, Al-Ti plating solutions were prepared by adding 1.0 mol of tetramethylammonium chloride to each solution. Using these solutions, the procedure was carried out in the same manner as described above to obtain various Al-Ti brazing materials. Any of the obtained brazing materials could be used to bond with various ceramics, making it possible to fabricate ceramic composite substrates.

[0032] (Example 6) In Example 1, Al-Ti plating solutions were prepared by adding 0.1 mol of tetramethylammonium chloride to each solution. Using these solutions, the procedure was carried out in the same manner as described above to obtain various Al-Ti brazing materials. Any of the obtained brazing materials could be used to bond with various ceramics, making it possible to fabricate ceramic composite substrates.

[0033] (Example 7) In Example 1, Al-Ti plating solutions were prepared by adding 1.5 mol of tetramethylammonium chloride to each solution. Using these solutions, the procedure was carried out in the same manner as described above to obtain various Al-Ti brazing materials. Any of the obtained brazing materials could be used to bond with various ceramics, making it possible to fabricate ceramic composite substrates. [Explanation of Symbols]

[0034] 1...first metal layer 2. Ceramic substrate

Claims

1. A process for preparing a plating solution containing Al ions and Ti ions, A step of immersing the substrate and electrodes in the aforementioned plating solution and applying an electric current to form a first metal layer on the substrate consisting of 0.01 at% to 10 at% Ti, with the remainder being Al and unavoidable impurities. It has, In the process of preparing the aforementioned plating solution, Mixing titanium tetrachloride into a plating solution containing Al ions. Immersing metallic titanium in the aforementioned plating solution containing Al ions, The titanium metal and a metal plate paired with the titanium metal are immersed in a plating solution containing Al ions, and the titanium metal is dissolved by passing a direct current through it, with the titanium metal as the anode and the paired metal plate as the cathode. A method for producing an aluminum-based brazing material, characterized by incorporating Ti as an ion into the plating solution containing Al ions by any of the following methods.

2. The method for producing an aluminum-based brazing material according to claim 1, wherein the plating solution containing Al ions is a plating solution obtained by mixing dimethyl sulfone and anhydrous aluminum chloride.

3. The method for producing an aluminum-based brazing material according to claim 1, wherein the plating solution containing Al ions is further a plating solution mixed with ammonium chloride.

4. In the process of preparing the plating solution, the titanium metal and the paired metal plates are immersed in the plating solution containing Al ions, and the titanium metal is dissolved by passing a direct current through it with the titanium metal as the anode and the paired metal plates as the cathode. The method for manufacturing an aluminum-based brazing material according to claim 1, wherein the electrode that serves as the anode is the titanium metal in the form of a ball or pellet filled in an insoluble case.

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