JP2019044234A - Production method of metallic film formed product - Google Patents

Abstract

To provide a production method of a metallic film formed product executable inexpensively in comparison with a conventional laser plating method, and excellent in adhesion between a substrate and the metallic film; and to provide the metallic film formed product.SOLUTION: There is provided a production method of a metallic film formed product, having a pretreatment step (S1) for processing the surface of a substrate in a wet system, and drying it, a fluid dispersion coating step (S2) for obtaining a coating film by coating fluid dispersion containing metallic fine particles partially on the surface of the substrate after the pretreatment step, and a laser sintering step (S3) for forming a sintered film of the metallic fine particles partially on the surface of the substrate by irradiating a laser beam to the coating film.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a metal film-formed article and a method of manufacturing a metal film-formed article.

  As a prior art related to the present invention, there is Patent Document 1 which discloses a method of forming a laser-sintered film having high adhesion to a metal substrate. This method is a metal film forming method in which noble metal plating such as gold or silver is plated on the surface of a base metal having a passivation film, and the surface of the base metal is irradiated with laser light to form the base metal. Is applied to a noble metal nanoparticle dispersion liquid in which a noble metal nanoparticle is dispersed in a solvent and then dried, and then a laser is applied to the noble metal nanoparticle coating film. It is a metal film formation method of irradiating light and sintering precious metal nanoparticles.

  Further, in Patent Document 1, a metal film is coated with a liquid repellent agent on the surface of the base metal before the surface activation step, and the liquid repellent agent is also decomposed and removed simultaneously, thereby limiting the application region of the noble metal nanoparticle dispersion. It is a formation method. A pulsed green laser with a wavelength of 532 nm is used for the surface activation step, and a semiconductor laser with a standing wave with a wavelength of 915 nm is used for sintering the metal nanoparticles.

Patent No. 5760060

  The above-mentioned Patent Document 1 is a complete dry process, which is an effective method for obtaining adhesion of a sintered film, but it has two specifications of a green laser for surface activation and a semiconductor laser for metal nanoparticle sintering. Since different laser irradiation devices are required, there is room for improvement in terms of cost reduction of the devices.

  In addition, there are mechanical polishing methods such as blasting in the surface activation step, but in order to construct a dry process by combining this blasting step and the metal nanoparticle laser sintering film forming method, scattering of blast abrasive powder There is a problem that it becomes expensive when blasting is performed in another process such as a problem or outsourcing.

  In view of the above circumstances, the present invention can provide a method for producing a metal film-formed product and a metal film-formed product, which can be implemented inexpensively as compared with the conventional laser plating method and have excellent adhesion between a substrate and a metal film. It is provided.

  In order to solve the above-mentioned problems, the present invention partially treats the surface of the substrate with a wet treatment and dries it, and partially applies a dispersion containing metal fine particles on the surface of the substrate after the pretreatment step. And forming a sintered film of metal fine particles on the surface of the substrate by irradiating a laser beam to the coated film to form a coated film. Provided is a method of producing a molded article.

  Further, the present invention has a substrate and a metal film formed on the surface of the substrate, the substrate is made of a metal forming a passivation film, and the metal film is made of gold, silver, copper, tin Alternatively, the present invention provides a metal film-formed article comprising nickel, wherein the metal film has a melt-solidified structure.

  More specific configurations of the present invention are described in the claims.

  According to the present invention, it is possible to provide a method for producing a metal film-formed product and a metal film-formed product, which can be implemented inexpensively and have excellent adhesion between a substrate and a metal film, as compared with the conventional laser plating method. Can.

  Problems, configurations, and effects other than those described above will be clarified by the description of the embodiments below.

Flow chart showing an example of a method for producing a metal film-formed article by a conventional wet plating method Flow chart showing an example of a method for producing a metal film-formed article by the laser plating method of the present invention Graph showing the results of XPS analysis before chemical polishing process of 64 titanium alloy substrate Graph showing the results of XPS analysis after chemical polishing, washing with water and drying (in air) steps of 64 titanium alloy substrate Graph showing light transmission, absorption and reflection spectra of gold nanoparticles The schematic diagram which shows an example of the apparatus for enforcing the manufacturing method of the metal film formation goods of this invention The schematic diagram which shows the other example of the apparatus for enforcing the manufacturing method of the metal film formation goods of this invention SIM image of silver nanoparticle laser sintered film cross section formed on 64 titanium substrate of Example 2

  From the background described above, the present inventor examined using a wet metal plating pretreatment step as a pretreatment for laser plating, instead of using a dry laser treatment or a blast treatment. That is, a pretreatment step including part or all of degreasing, pickling and activation pretreatment in wet metal plating, and metal nanoparticle laser firing on metal substrate by metal nanoparticle laser sintering method (HLP) A method of forming metal nanoparticle laser sintered film on metal substrate fused with conjunctiva formation process was discussed. “HLP” (High speed Laser Plating) is a registered trademark of M & M Research Institute, Inc.

Here, the problems that may occur when combining the pretreatment of the wet plating method and the laser sintering of the laser plating method will be described. When partially plating the surface of a titanium alloy such as 64 titanium (6 mass% Al-4 mass% V-Ti alloy) by wet electroplating, etc., oxidation of titanium, which is a highly stable passivation film on the surface of the titanium alloy Since the film (titanium oxide / TiO ₂ ) is formed, it is necessary to remove this passivation film. The thickness of the TiO ₂ film is about several nm for a natural oxide film, and about several tens of nm for a titanium material that has been manufactured by rolling or the like and has been heated. Normally, for pure titanium and titanium alloy substrates, the passivation film is removed by pickling with an aqueous solution of hydrofluoric acid (HF), and then electro nickel plating or electro copper plating is performed, but with this method sufficient plating adhesion Can not be obtained. This is due to the instantaneous self-healing action of the passivation film as a property of titanium. That is, in the water-washing process after oxide film removal by pickling, the oxide film of titanium is instantaneously formed by dissolved oxygen contained in water. In particular, the self-repairing action of titanium, titanium alloy, kovar, magnesium alloy and stainless steel is instantaneous.

  From this, it is very difficult to form a highly adhesive electroplating film on a titanium surface in a normal process, and as another method, the surface of titanium or a titanium alloy is polished by an abrasive such as alumina powder or quartz powder. The method (reference 1) which carries out a blast process (fine particle powder spray polishing process) and performs electroplating (general reference 1) comes to be used generally.

Reference 1: Research bulletin of Fukui Institute of Technology No. 29 1999
In this method, adhesion is achieved by the anchor effect due to surface roughening, but a special blasting process must be performed before plating, and the process of outsourcing the blasting process is increased and the cost increases. There is. Further, there is the following reference patent document 2 as a method for pre-plating titanium.

Reference 2: Japanese This method No. Hei 10-265974 relates to HI or by the etchant containing I _2, plating pretreatment etching solution to the titanium or titanium alloy as sulfuric acid and iodine source. It is described as useful as a blasting alternative, as it provides fine asperities that replace blasting. However, the method of forming fine asperities on these titanium alloy surfaces on these titanium is in close contact with the interdiffusion bond in metal nanoparticle laser sintering method because of the method of securing the adhesion by the anchor effect. The properties are low, and peeling and swelling occur in temperature cycle tests and thermal shock tests, so that high reliability in practical use can not be obtained.

  Therefore, as a result of intensive investigations, the inventor found a method for producing a metal film-formed product that can overcome the problem of the self-repairing action of the passivation film generated in the pretreatment step of wet plating and can lead to laser plating. The Hereinafter, the method for producing a metal film-formed article of the present invention will be described in detail in comparison with a conventional wet plating process.

  FIG. 1 is a flow chart showing an example of a method of producing a metal film-formed article by a conventional wet plating method, and FIG. 2 is a flow chart showing an example of a method of producing a metal film-formed article by a laser plating method of the present invention. . As shown in FIG. 1, the conventional method for producing a metal film by a wet plating method includes a total of 13 steps of 5 steps of pre-treatment, 4 steps of plating treatment and 4 steps of post-treatment. The method of producing a metal film by the laser plating method of the present invention shown in FIG. 2 is a total of nine steps of six steps of pretreatment and three steps of laser sintering treatment. In the present invention, since the plating is performed by dry laser sintering, it is necessary to dry the substrate after wet pretreatment. Therefore, although the drying step (6) is included in the pretreatment and the pretreatment step is one more than the conventional wet plating of FIG. 1, the total number of steps can be significantly reduced according to the present invention. I understand. From the comparison between FIG. 1 and FIG. 2, the wet plating method is expensive in equipment cost due to the long process, and the equipment for treatment of waste liquid and washing drainage is required.

  The present invention utilizes the pretreatment process in the conventional wet plating method as it is, and connects the metal nanoparticle laser sintering process as the next process. As a result, the wet plating process and the post-treatment processes such as washing and drying in the wet plating can be omitted, and significant reduction of the process cost and cost reduction can be achieved. FIG. 2 shows an example in which a drying step (6) as pretreatment and a metal nanoparticle laser sintering process (7) to (9) are connected to the wet electroplating pretreatment step.

  Next, the method for producing the metal film-formed article of the present invention will be described in detail. The method for producing a metal film-formed article of the present invention comprises a chemical polishing step (acid washing (S1)) of chemically polishing the surface of a substrate using a chemical polishing solution containing an oxidizing agent (forced oxidizing agent), and chemical polishing The dispersion liquid application process (S2) which applies the dispersion liquid containing metal particulates on the surface of the base material to obtain a coating film, and the laser sintering process which irradiates a laser beam to the coating film to obtain a sintered film of metal microparticles ( S3) is included as an essential step.

  The substrate for forming the metal film is not particularly limited, but includes, for example, a substrate comprising aluminum, aluminum alloy, magnesium, magnesium alloy, stainless steel, kovar, hastelloy, copper, copper alloy and nickel plated metal. . The present invention is particularly effective for metal materials (difficulty plating materials) which form a strong passivation oxide film in a natural environment and in which it is difficult to form a highly adhesive plated film by wet electroplating. In the metal nanoparticle laser sintering method, the laser energy heats the interface between the substrate and the metal nanoparticle, so that even if there is a thin passivation film on the substrate, metal atoms are interdiffused from the defect portion. It has the feature that high adhesion strength laser sintered film can be obtained. As a metal which produces a strong passivation film in the natural environment, titanium, titanium alloy, stainless steel, magnesium alloy, aluminum, aluminum alloy, kovar, hastelloy and the like are known. The laser sintering process will be described in detail later.

  As shown in FIG. 2, the substrate may be subjected to degreasing treatment (1) and water washing treatment (2). These treatments are similar to conventional wet plating methods. The degreasing is a process of decomposing and removing the oil component of the base material with an alkaline degreasing solution. As the degreasing treatment, a dipping method, a cathodic electrolytic degreasing method and an ultrasonic degreasing method are mainly used. In the degreasing method, there are also a method of washing with an organic solvent such as hydrocarbon and a method of immersing in an aqueous solution containing a surfactant.

  The chemical polishing step (S1) is performed for the purpose of removing the passivation film formed on the surface of the substrate and etching the surface of the substrate. This process is characterized in that impurities and additive metal elements which are poorly soluble in acid can be dissolved and removed. Silica and carbon can not be removed, but since they adhere as attached fine particles, when they are included, they can be removed by performing ultrasonic cleaning in water after chemical polishing.

In this chemical polishing process, the passivation film is dissolved and removed, and the surface layer of the substrate is dissolved according to the material by about 0.1 to several μm by the action of a forced oxidizing agent to expose metal atoms on the substrate surface. At the same time, the substrate surface can be smoothed by the polishing action. The action of forced oxidants is described in the following references:
Reference: Surface technology Kawamura; Principle and application of hydrogen peroxide based chemical polishing solution Vol. 57 No. 12 PP. 26-30
The principle of chemical polishing is to oxidize a metal once with a forced oxidizing agent and dissolve it as a soluble salt. Therefore, it is possible to etch without leaving a residue.

  When treated with a chemical polishing solution containing this forced oxidizing agent, the passivation film having a thickness of about 1 nm is removed and the base material is further etched. Therefore, lattice defects such as dislocation defects as well as surface flaws of metal materials are removed. It can be removed. In the metal material, the thickness of the passivation film becomes a thickness of several nm by rolling or the like, and there may be a case where processing distortion remains on the surface. For this reason, since the etching depth by chemical polishing liquid changes with material types and processing history, it is preferable to select optimal etching conditions (composition and processing time of chemical polishing liquid) and depth by material and processing history.

A commercially available thing can be used as chemical polishing liquid used at a chemical polishing process. For example, a chemical polishing solution clean etch TCP-09 ("clean etch" is a registered trademark of Hishie Chemical Co., Ltd.) manufactured by Hishie Chemical Co., Ltd. can be used. This chemical polishing solution is a polishing solution obtained by adding ammonium acid fluoride and hydrogen peroxide solution as an oxidizing agent to water. After the chemical polishing step S1, in order to remove the chemical polishing solution remaining on the substrate, it is preferable to wash the substrate with water (5) and to dry it (6). Drying is preferably performed in an inert atmosphere or in vacuum in order to prevent the formation of the passivation film on the surface of the substrate, in the case of a substrate which is particularly susceptible to the formation of the passivation film. The inert gas atmosphere is preferably dried by, for example, blowing nitrogen (N ₂ ) gas.

  FIG. 3 is a graph showing the results of XPS (X-ray Photoelectron Spectroscopy) analysis before the chemical polishing process of 64 titanium alloy substrate, and FIG. 4 is the chemical polishing process of 64 titanium alloy substrate, water washing and drying (in air) process. Is a graph showing the results of XPS analysis after lapse of time. Table 1 also shows the atomic ratio (atomic%) by XPS analysis of the surface before and after chemical polishing. Table 1 also shows the alloy components of the 64 titanium alloy.

  As shown in FIG. 4, a peak of pure iron (Fe2p) which does not appear before chemical polishing appears after chemical polishing. Iron of 0.4 mass%> is added to the 64 titanium alloy in order to improve the rollability, but the peak of iron is not observed before chemical polishing. Also from Table 1, Fe2p is 0 mass%.

Further, it is understood from the atomic ratio of Ti and O that the surface of the 64 titanium alloy substrate before chemical polishing is titanium dioxide (TiO ₂ ). Therefore, it can be seen that the surface of the 64 titanium alloy substrate before the chemical polishing process is covered with a passivation film of TiO ₂ . Although the presence of TiO ₂ can be confirmed even after chemical polishing, a component of Fe appears at 2.12 mass%. From this, the surface of 64 titanium after chemical polishing is in a state in which Fe and a passivation film of TiO ₂ coexist. When a metal nanoparticle paste is applied to a substrate exposed to such an extent and irradiated with a laser, the Fe and the metal nanoparticles mutually diffuse, resulting in high adhesion between the substrate and the sintered film.

  Furthermore, the present invention has an anti-oxidation film forming step of forming an anti-oxidation film on the surface of the base material by washing the base material with washing water to which an antioxidant (inhibitor) is added after the chemical polishing step. It may be As described above, titanium and titanium alloys achieve high adhesion between the substrate and the sintered film due to the presence of exposed Fe even if there is a passivated film on the surface of the substrate after the chemical polishing process. it can. However, in order to prevent the formation of the passivation film on a substrate which has a larger self-healing action of the passivation film than titanium and titanium alloy and which is covered with the passivation film instantaneously after the chemical polishing process In addition, it is effective to form an antioxidant film on the surface of the substrate after the chemical polishing process. Furthermore, since the antioxidative coating has water repellency and can prevent scattering of the metal nanoparticle dispersion, it becomes unnecessary to apply a water repellent before applying the metal nanoparticle dispersion. In addition, by partially decomposing and removing the antioxidant film by laser irradiation, it is possible to apply the metal nanoparticle dispersion liquid only to the portion that is decomposed and removed. This makes it possible to specify the application area more clearly, and enables clear pattern formation on the application boundary. In the case of dispensers and ink jet printing, while the shape of droplets remains at the boundaries of the pattern to fly droplets, in this method the boundaries of the patterns are straight, and sharper patterns such as characters can also be printed. become. Since a semiconductor laser or a YAG laser can be used for decomposing and removing the anti-oxidation film, the same laser beam source as the sintering of the gold nanoparticles can be used.

  Specifically, a mixed solution containing 0.1 mass% of DICHAN (dicyclohexyl ammonium nitride) in water can be used as the mixed solution containing the antioxidant. By using such a mixed solution, an antioxidant film can be formed on the surface of the substrate, and self-repairing of the passivation film can be prevented even in the air. A metal nanoparticle dispersion liquid is applied to the surface of such an antioxidant film, and a laser-sintered film having high adhesion strength can be formed by irradiating a laser beam. As the antioxidant, in addition to DICHAN, benzotriazole of an amine compound effective for aluminum, nickel and the like can be used. As an antioxidant, triazoles, imidazoles or nitrites can be used. Select the most suitable antioxidant according to the type of metal.

  Next, a metal nanoparticle dispersion (conductive paste) is applied to the surface of the substrate (S2). As the metal nanoparticle dispersion liquid, for example, a viscosity obtained by mixing highly conductive metal nanoparticles such as gold, silver, copper, tin or nickel having an average particle diameter of 1 to 100 nm, an organic solvent, a binder, a viscosity modifier, etc. It can be used uniformly dispersed in the body. The pattern printing by screen printing, dispenser printing, etc. can be used for the printing method of a conductive paste. Alternatively, the entire surface printing using a squeegee may be performed, and after the conductive metal film forming step described later, the conductive paste of the portion other than the portion irradiated with the laser beam may be removed by a solvent.

  The viscosity of the metal nanoparticle dispersion is preferably 5 to 10 mPa · s in inkjet printing or dispenser printing. When the viscosity is less than 5 mPa · s, the content of the metal particles is reduced, and the solvent component is increased, so that the drying time in the drying step to be described later becomes long. Moreover, when it exceeds 10 mPa · s, the viscosity becomes too high and the printability is deteriorated.

  The film thickness of the coating film (the printing thickness of the conductive paste) is thicker than the final required film thickness obtained in the laser sintering step (S3). Although depending on the volume ratio of metal particles in the conductive paste, when the volume ratio is 10%, a thickness about 10 times the thickness of the target sintered film is applied.

  After the printing of the conductive paste, heat drying (8) is performed in order to remove the excess organic solvent contained in the printed conductive paste. The conditions of the drying temperature and time are preferably 100 to 120 ° C. and 1 to 15 minutes, in order to suppress oxidation of the metal particles during drying in the air. The drying process can be shortened in time if it is performed under a weak pressure of about 1/2 (0.05 MPa) of the atmospheric pressure.

  Next, the surface of the coated film subjected to the drying treatment is irradiated with a laser beam to carry out a laser sintering step (S3) for obtaining a sintered film of metal fine particles. In this laser sintering step S3, metal nanoparticles are sintered by laser energy, and the substrate is heated by laser light transmitted through the metal nanoparticle dispersion, and metal atoms of the metal nanoparticles by substrate heating and metal atoms of the substrate Promote the mutual diffusion of the metal and obtain high adhesion strength. The laser irradiation conditions for sintering metal particles contained in the coating film include frequency, beam diameter, power (or energy), scanning speed, laser beam focal position, etc., and adhesion between the substrate and the metal film can be obtained. Also, the value is set to a value at which the metal nanoparticles sinter.

  FIG. 5 is a graph showing the light transmission, absorption and reflection spectra of gold nanoparticles. As shown in FIG. 5, the gold nanoparticles have a high transmittance of 70% and an absorptivity of 20% in the 915 nm wavelength region of the semiconductor laser. For this purpose, 70% of the laser energy is transmitted and consumed to heat the metal substrate. The laser irradiation rapidly raises the temperature of the substrate interface, while the gold nanoparticles begin to sinter. At this time, mutual diffusion of metal atoms of each other is accelerated at the interface between the metal substrate and the gold nanoparticles. Also, with a rapid temperature rise, the solvent component in the gold nanoparticle dispersion expands, volatilizes and deviates.

  As described above, the method of forming a sintered film on a metal substrate by metal nanoparticle laser sintering method is required not only for the simplification of the apparatus but also for a film excellent in adhesion, so it is required for automobile and aircraft applications It has the great feature of enduring the reliability test such as temperature cycle test and thermal shock test.

As the laser beam, in addition to the above-described semiconductor laser having a wavelength of 915 nm, a YAG laser having a wavelength of 1064 nm and an Nd: YVO ₄ green laser having a wavelength of 532 nm can be used.

  FIG. 6 is a schematic view showing an example of an apparatus for carrying out the method for producing a metal film-formed article of the present invention, and FIG. 7 is another example of an apparatus for carrying out the method for producing a metal film-coated article according to the present invention. It is a schematic diagram which shows an example. FIG. 6 shows an example of an apparatus for forming a metal nanoparticle sintered film partially on the surface of a metal strip while continuously rolling up a long metal strip 15a. Further, FIG. 7 shows an example of an apparatus for sequentially transporting and processing metal-worked parts by a transport machine.

  The metal strip serving as the base material (target for forming a metal film) in the apparatus of FIG. 6 is a copper alloy strip, a nickel-plated copper alloy strip, a 42 alloy strip (42 mass% Ni-Fe) used for a lead frame for semiconductor It is a Kovar strip or the like, usually 0.1 to 0.3 mm in thickness, 20 to 50 mm in width, and about 200 m in length. Such metal shapes have been conventionally electroplated in a continuous winding method. Usually, in products for semiconductors, partial plating of gold or silver is performed as a metal film. In the connector application, phosphor bronze having excellent spring characteristics, nickel-plated phosphor bronze, high-strength copper alloy, stainless steel and the like are used. In the case of connectors, gold plating is the mainstream, but there are also cases of silver plating and tin plating. These strips may be flat plates before pressing or may be pressed. In either case, electroplating is performed while being wound up continuously.

  In the case of normal electroplating, the device width is about 2 m and the length is as long as about 30 m, which is a total length of about 10 m for the pretreatment step, about 10 m for the plating step and about 10 m for the post treatment step. . According to the present invention, although the pretreatment process is about 10 m as well, the total length of the metal nanoparticle dispersion application process, the drying and the laser irradiation process is about 2 m, so the total apparatus length can be shortened to about 12 m. . This length is about 1/3 of the length 30 m of the conventional wet electroplating method. The installation installation area can be small by this amount.

  Further, the price of the continuous winding type electroplating apparatus is usually about 60 million yen, but the price occupied by the pretreatment process is about 10 million yen. This is because, in electroplating, the cost of the DC power supply and the post-processing step is high. With the apparatus for carrying out the method for producing a metal film-formed article of the present invention, the apparatus price is the same as the pre-processing process price of 10 million yen, but the price of the laser plating process is 20 million yen in total. Because of this, the cost of the apparatus according to the present invention can be reduced to a total of 30 million yen. This price is about half of that of a wet electroplating apparatus.

  Moreover, since the acid and alkaline aqueous solution discharged | emitted by the pre-processing process do not contain a harmful substance, a special waste-liquid-treatment apparatus or a waste-water-treatment apparatus is not required. However, in wet electroplating, incidental equipment costs of about 30 million yen are generated in addition to the device price of 60 million yen, such as a treatment device for harmful substances such as cyanide, a precious metal recovery device, and a high purity water production device. Including this price, the wet electroplating apparatus totals 90 million yen, which is three times the price of the apparatus of the present invention, which is very expensive.

  Gold and silver plating is partially plated in both semiconductor and connector applications, but in wet electroplating, soft silicone rubber is processed into a hard resin substrate and fine holes are formed. Press the mask to perform plating. This plating mask is very expensive, and in the case of a wet partial electroplating apparatus, the plating mask is a consumable item, and the maintenance cost of mask replacement is increased. The range of partial plating is about 1 mm at the maximum and 0.2 mm at the minimum, and has a shape as shown in the metal nanoparticle dispersion liquid coating film 8 'and the laser sintering film 10' in FIG. In addition, the partial plating shape has a circular shape or a rectangular shape, and according to the shape, holes are formed in the mask in electroplating. The metal nanoparticle laser sintered film forming apparatus of the present invention is provided with the high-speed drawing dispenser 12 capable of discharging a minute amount of metal nanoparticle dispersion, and the pattern change can be made by the soft input change of the dispenser according to the shape of partial plating. It is. For this reason, it is not necessary to newly purchase a mask each time as in wet electroplating. Since the cost of the wet electroplating mask usually costs about 1 million yen, this price is added to the product cost, and if the production quantity is small, it leads to cost increase. In this regard, the present invention does not incur the expense of masks.

  Although the solvent drying device 9 in the present invention is performed to remove a part of the solvent of the metal nanoparticle dispersion, in the case where the temperature of the coating stage is raised to about 100 ° C. in the metal nanoparticle dispersion coating device 8, in particular When the coating amount of the metal nanoparticle dispersion is small, solvent drying may sometimes be omitted. When the residual solvent is completely removed, the metal nanoparticles start to aggregate and form an aggregated film in which the solvent remains while remaining in the interior, so a film in which a large amount of voids are generated inside, and subsequent laser irradiation The sintered film has many void defects. Therefore, the drying conditions are optimum depending on the thickness of the metal nanoparticle coating film, the material of the metal strip (shape, thermal conductivity), the temperature of the coating stage, the viscosity of the metal nanoparticle dispersion, the solvent content, etc. Set the conditions. As the drying method, many methods such as hot air drying, infrared heater heating, stage heating, and reduced pressure drying can be used.

  In the laser irradiation apparatus 10, a standing wave semiconductor laser having a wavelength of 915 nm or a standing wave YAG laser having a wavelength of 1064 nm can be used. In the laser irradiation optical system 13, an optical system capable of high-speed drawing irradiation of a galvano mirror system can be used. The high-speed laser irradiation position coordinate setting can also be performed using a property XYZ stage capable of high-speed movement. Since the oscillator 14 for laser light is small, it may be disposed near the stage of the metal nanoparticle laser sintered film forming apparatus.

  FIG. 7 shows an example of a metal nanoparticle laser sintered film forming apparatus for a single-piece metal-processed part processed by press processing or cutting processing. In the case of single-piece metalworking parts, workers manually attach the metal parts to the parts suspension rack and manually convey each process. However, FIG. 7 shows the case of the automatic conveyance method. . This method is a method of conveying the metal-processed part 15b using the part delivery machine (parts transfer machine) 2b. The carrier can move up and down and sideways, and can be programmed to process time. The basic function is the same as that of the continuous winding system shown in FIG. 3 except that the mechanism for transferring parts is the same, but compared with the continuous winding system, the length of the device is longer because there are no unwinding machine and winding machine. It can be shortened. However, the price of the apparatus does not change significantly between the winding method and the transfer method, and is about 30 million yen. The single component transport is suitable for small amounts of various types, and therefore suitable for semiconductor lead frames and connectors, as well as metal processing components for many applications that have been machined and pressed. For example, processed titanium products, stainless steel products, Kovar products, magnesium alloy products, etc. have recently been developed for next-generation EVs, aircraft, and applications, but these can also be used for trial development is there.

  Hereinafter, the present invention will be more specifically described based on examples.

  In this example, a titanium alloy substrate was prepared as a base material, and a metal film-formed product having a sintered film of silver nanoparticles formed on the surface of the substrate was manufactured, and the adhesion was evaluated.

  Ultrasonic degreasing treatment of a 64 titanium alloy substrate (6Al-4V-Ti alloy, t 0.41 mm × 12.5 mm × 12.5 mm) with an alkaline degreasing solution for 1 minute, and after washing with tap water, a chemical polishing solution Chemical polishing was performed using clean etch TCP-09 (chemical polishing solution manufactured by Hishie Chemical Co., Ltd.). This chemical polishing solution is a chemical polishing solution of an aqueous system of 64 titanium alloy or pure titanium containing 10 mass% of ammonium acid fluoride and 20 mass% of hydrogen peroxide as a forced oxidizing agent. The chemical polishing solution enables not only removal of the passivation film on the surface but also treatment for etching and smoothing the surface of the metal substrate (base material). The chemical polishing conditions were 90 seconds at normal temperature to etch the substrate about 1 μm thick.

  Silver nanoparticle paste NPS-J (manufactured by Harima Chemicals, Inc.) is applied on the surface of the etched substrate to a thickness of about 3 μm by spin coating, and then dried in the air at 100 ° C. for 1 minute. And excess solvent components contained in the silver nanoparticle paste were removed.

  Then, the silver nanoparticle paste was sintered by irradiating the silver nanoparticle coating film with semiconductor laser light (stationary wave) having a wavelength of 915 nm. Laser irradiation conditions were a beam spot diameter of 0.4 mm, an output of 10 W, and a scanning speed of 0.5 mm / s. By scanning the laser beam, a linear sintered film could be formed.

The adhesion of the laser-sintered silver nanoparticle film was measured by a tensile strength test of the adhesive terminal. As a result, a high adhesion strength of 351 kg / cm ² could be obtained.

  In Example 2, an oxidation-resistant film forming step was carried out after the chemical polishing treatment of Example 1, and a sintered film of silver nanoparticles was formed on a 64 titanium alloy substrate in the same manner as in Example 1 except for this. In the step of forming an anti-oxidation film, after the substrate is washed with washing water containing 0.1 mass% of DICHAN as an antioxidant (inhibitor), the finish washing with pure water is carried out, and it is dried to oxidize DICHAN on the surface of the 64 titanium substrate. A protective coating was formed.

The adhesion of the laser-sintered silver nanoparticle film was measured by a tensile strength test of the adhesive terminal. As a result, a high adhesion strength of 393 kg / cm ² , which is 10% higher than that of Example 1, could be obtained. This is considered to be because titanium was prevented from forming a passivation film by self-repairing by forming an anti-oxidation film after the chemical polishing treatment.

  FIG. 8 is a SIM image of a cross section of a silver nanoparticle laser sintered film formed on a 64 titanium substrate. As shown in FIG. 8, the crystal structure of silver is clearly observed, and it can be seen that the silver nanoparticles are sintered and bulkized. The thickness of the sintered film is about 0.3 μm, and the thickness is 1/10 of the coating film thickness (about 3 μm) due to bulking. In the sintered film, voids (voids) having a diameter of about 2 μm are observed in the film, which are independent voids caused by the aggregation of the residual solvent component contained in the silver nanoparticle paste. Usually, through holes called pinholes are generally used in wet electroplating, but the laser-sintered film is characterized by being independent holes which do not penetrate. While wet electroplating can reduce the generation of pinholes by adjusting the current density and pH of the plating solution, laser sintering can optimize the drying conditions after applying the silver nanoparticle paste and optimize the laser irradiation conditions. It is possible to reduce the occurrence of holes.

Comparative Example 1
In Comparative Example 1, in place of chemical polishing of the surface of the 64 titanium alloy substrate in Example 1, polishing was performed with emery paper. Specifically, the surface of the 64 titanium alloy substrate was subjected to automatic rotational polishing with # 4000 emery polishing paper in a normal temperature atmosphere. A silver nanoparticle sintered film was formed on the surface of the substrate in the same manner as in Example 1 except for the above, and adhesion was evaluated. As a result, a silver nanoparticle laser sintered film with an adhesion strength of 245 kg / cm ² was obtained. This value was about 40% lower in adhesion strength as compared with the chemical polishing method of Example 1. This is considered to be due to the decrease in adhesion because the oxide film is instantaneously regenerated to be thick due to the frictional heat of the emery polishing.

Comparative Example 2
In Comparative Example 2, in place of chemical polishing in Example 1, ultrasonic degreasing treatment was performed for 1 minute with an aqueous alkaline solution. A silver nanoparticle sintered film was formed on the surface of the substrate in the same manner as in Example 1 except for the above, and adhesion was evaluated. As a result, a silver nanoparticle laser sintered film having an adhesion strength of 130 kg / cm ² was obtained. This value is about 1⁄3 of the adhesion strength of the value of Example 1. This is because the passivation film on the surface of the 64 titanium alloy substrate becomes a complete diffusion barrier film that suppresses the interdiffusion of metal atoms between the 64 titanium alloy substrate and the silver nanoparticle laser sintered film.

  From the results of Example 1 and Comparative Examples 1 and 2, it is clear that the method using a chemical polishing solution is the best as a method of removing the passivation film on the surface of the 64 titanium alloy substrate and further etching the base material. It became. On the other hand, it was found that sufficient adhesion can not be obtained only by mechanical polishing using emery paper or degreasing treatment for removing the oil adhering to the surface.

  As described above, according to the present invention, there is provided a method for producing a metal film-formed product and a metal film-formed product, which can be implemented inexpensively and have excellent adhesion between a substrate and a metal film, as compared with the conventional laser plating method. It has been demonstrated that it can be done.

  The following effects can be obtained by connecting the metal nanoparticle laser sintered film forming process to the pretreatment process performed by wet electroplating or the like.

  (I) The cost of the plating apparatus can be reduced to 1/2.

  (Ii) The length of the plating apparatus can be shortened to 1/3 and the apparatus installation area can be reduced.

  (Iii) The cost of the plated product can be reduced.

  (Iv) Form a stable passivation film, and it is difficult to form a plating film having excellent adhesion by conventional wet plating, titanium, titanium alloy, stainless steel, magnesium alloy, aluminum, aluminum alloy, kovar, Provided is a method capable of forming a metal nanoparticle laser sintered film having high adhesion at a low cost to a highly corrosion resistant metal substrate such as hastelloy.

  (V) With respect to highly corrosion resistant metal substrates such as titanium, titanium alloy, stainless steel, magnesium alloy, aluminum, aluminum alloy, kovar, hastelloy and the like which form stable passivation film and difficult to form plated film By using a metal nanoparticle laser sintered film having high adhesiveness, application to the electric contact material of these materials and a semiconductor mounting substrate becomes possible.

  The present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations.

  DESCRIPTION OF SYMBOLS 1 ... Metal nanoparticle laser sintering film formation apparatus, 2a, 2b ... Delivery machine, 3 ... Degreasing tank, 3 '... Degreasing liquid, 4 ... Washing tank, 4' ... Washing water, 5 ... Pickling tank, 5 '... Acid Washing liquid 6: water washing tank 6 'washing water 7' drying device 7 'heater 8' metal nanoparticle dispersion liquid coating device 8 'metal nanoparticle dispersion liquid coating film 9 solvent drying device , 9 '... heater, 10 ... laser irradiation device, 10' ... laser sintered film, 11 ... winding machine, 12 ... dispenser, 13 ... laser irradiation optical system, 14 ... oscillator, 15a ... metal strip, 15b ... metal part.

The present invention relates to a method for producing a metallic film formed article.

In order to solve the above-mentioned problems, the present invention partially treats the surface of the substrate with a wet treatment and dries it, and partially applies a dispersion containing metal fine particles on the surface of the substrate after the pretreatment step. the dispersion coating to obtain a coating film Te, the sintered membrane of the fine metal particles on the surface of the irradiated with laser light substrate the coating film have a laser sintering step of partially forming, pre-treatment step, Disclosed is a method for producing a metal film-formed article comprising a chemical polishing step of performing chemical polishing using a chemical polishing solution containing an oxidizing agent .

As described above, according to the present invention, as compared with the conventional laser plating, inexpensive to practice, and it can provide a manufacturing how the metal coating formed article having excellent adhesion to the substrate and the metal coating Was demonstrated.

Claims (13)

A pretreatment step of wet treating and drying the surface of the substrate;
A dispersion liquid applying step of partially applying a dispersion containing metal fine particles onto the surface of the base material after the pretreatment step to obtain a coated film;
And a laser sintering step of partially forming a sintered film of the metal fine particles on the surface of the substrate by irradiating the coated film with a laser beam.   The method for producing a metal film-formed article according to claim 1, wherein the pretreatment step includes a chemical polishing step of chemically polishing using a chemical polishing solution containing an oxidizing agent.   Furthermore, between the chemical polishing process and the dispersion application process, an antioxidant film forming process of forming an antioxidant film on the surface of the substrate by washing the substrate with an antioxidant added washing water is included. The method for producing a metal film-formed article according to claim 2, wherein   The metal film formation according to claim 3, further comprising a drying step of drying the substrate in an inert gas atmosphere or vacuum before the oxidation preventing film forming step and the dispersion liquid applying step. Product manufacturing method. Irradiating the surface of the anti-oxidation coating with a laser in the infrared region to remove the anti-oxidation coating;
The method for producing a metal film-formed article according to claim 3 or 4, wherein the dispersion is applied to a portion from which the anti-oxidation film has been removed.   The method for producing a metal film-formed article according to any one of claims 3 to 5, wherein the antioxidant is a triazole type, an imidazole type or a nitrite.   The said base material consists of titanium or a titanium alloy, aluminum, aluminum alloy, magnesium, a magnesium alloy, stainless steel, kovar, hastelloy, copper, a copper alloy, or a nickel plating metal, It is characterized by the above-mentioned. The manufacturing method of the metal film formation goods as described in item.   The said metal fine particle consists of gold | metal | money, silver, copper, tin, or nickel, and an average particle diameter is 1-100 nm, The manufacturing of the metal film formation goods of any one of the Claims 1 thru | or 7 characterized by the above-mentioned. Method. The metal according to any one of claims 1 to 8, wherein the laser light is a YAG laser having a wavelength of 1064 nm, a semiconductor laser having a wavelength of 915 nm, or an Nd: YVO ₄ green laser having a wavelength of 532 nm. Method for producing film-formed products.   The base material is a long metal strip or a pressed metal strip, and the metal strip is continuously unwound, and the pretreatment step, the dispersion liquid applying step and the laser sintering step are carried out. The metal film-formed article according to any one of claims 1 to 9, wherein the metal strip is wound after forming a metal film continuously and partially on the surface of the metal strip. Production method.   The base material is a flat or a metal part having a three-dimensional structure which has been pressed, and the metal part is carried by carrying out the pretreatment step, the dispersion liquid application step and the laser sintering step while conveying the metal part. The method for producing a metal film-formed article according to any one of claims 1 to 10, wherein a metal film is formed continuously and partially on the surface of the metal. A substrate, and a metal film formed on the surface of the substrate,
The substrate comprises a metal that forms a passivation film,
The metal film-formed article, wherein the metal film is made of gold, silver, copper, tin or nickel and has a melt-solidified structure.   The metal film formation according to claim 12, wherein the base material comprises titanium, titanium alloy, aluminum, aluminum alloy, magnesium, magnesium alloy, stainless steel, kovar, hastelloy, copper, copper alloy or nickel plated metal. Goods.

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