JP5773145B2 - Copper-based material having a copper diffusion prevention layer - Google Patents

Description

  The present invention relates to a copper-based material having a copper diffusion prevention layer.

  An illumination device using an LED (light emitting diode) has low energy consumption, has a long lifetime, and is widely attracting attention as a light source that replaces a heat-generating bulb and a fluorescent lamp.

  Packaged LED lighting units that use LEDs as light emitting elements are provided with a reflective part on which silver or aluminum with high glossiness and reflectivity is deposited in order to efficiently reflect the light emitted from the LED elements. (See Patent Document 1 below). It has also been reported that by applying silver plating to the reflective portion, absorption of blue, blue-green, green, etc. is suppressed, and a high light emission output can be obtained (see Patent Document 2 below).

  On the other hand, when copper or copper alloy that is inexpensive and has good heat dissipation is used as the base of the silver plating film, there is a problem that the reflectance decreases with time due to diffusion of copper atoms on the surface of the silver plating film. is there. In particular, white LED light-emitting elements are converted into visible light within the power consumption of about several tens of percent, others are heat, and they are spatially narrow due to their small size compared to other light sources. The heat tends to concentrate on the surface, and when used for a long period of time, a decrease in reflectance becomes a serious problem due to thermal diffusion.

  In a LED lighting unit having a silver-plated reflecting portion, a diffusion prevention layer made of a noble metal such as Pd or Rh is formed as a method for preventing components contained in the base of silver plating from diffusing into the silver plating film. Has been reported (see Patent Document 3 below). However, this method has a problem in that the noble metal component itself contained in the diffusion preventing layer diffuses into the silver plating film, resulting in a decrease in reflectance.

  In addition, for example, a printed wiring board having a Pd film, an Au film, or the like formed on the surface has a problem in that if copper as a circuit material diffuses on the surface, solderability and wire bonding properties are adversely affected.

JP 2005-56941 A Japanese Patent Laid-Open No. 9-293904 JP 2007-258514 A

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is a material in which a surface layer such as a silver film is formed using copper or a copper alloy as a base material such as an LED lighting unit. An object of the present invention is to provide a method capable of effectively preventing copper atoms contained in a base material from diffusing into a surface layer.

  The inventor has conducted extensive research to achieve the above-described object. As a result, after the palladium film or silver film is formed on the substrate made of copper or copper alloy, the nickel film or nickel alloy film is formed, thereby suppressing the diffusion of copper atoms contained in the base layer to the surface layer. For example, when a silver film is formed as a surface layer and used as a reflection part of an LED lighting unit, it has been found that a high reflectance can be maintained for a long period of time, and the present invention has been completed here. It was.

That is, the present invention provides a copper-based material having the following copper diffusion prevention layer and an LED lighting unit.
Item 1. In a material based on copper or copper alloy, a diffusion prevention layer having a structure in which a palladium film or a silver film and a nickel film or a nickel alloy film are sequentially laminated is formed on the substrate. A copper-based material having a copper diffusion prevention layer.
Item 2. Item 2. The copper-based material according to Item 1, wherein the surface layer has a silver film.
Item 3. Item 3. The copper-based material according to Item 2, which is a reflection part in the LED lighting unit.
Item 4. An LED lighting unit comprising a reflective portion made of the copper-based material according to Item 3 and an LED light emitting element.

Hereinafter, the copper-based material of the present invention will be described in detail.
The copper-based material of the present invention is a diffusion prevention layer having a structure in which a palladium film or a silver film, and a nickel film or a nickel alloy film are sequentially laminated on the base material of copper or a copper alloy. Is formed.

  The base material in the copper-based material of the present invention is copper or a copper alloy. The type of copper alloy is not particularly limited, but a copper alloy having a copper content of about 60% by weight or more is preferable. For example, a copper zinc alloy, a copper tin alloy, a copper nickel alloy, a copper aluminum alloy, or the like can be used. .

  The copper-based material of the present invention has a diffusion preventing layer having a laminated structure in which a palladium film or a silver film is formed on the substrate, and then a nickel film or a nickel alloy film is formed thereon.

  The method for forming the palladium film in the diffusion preventing layer is not particularly limited, and various methods such as a vapor deposition method such as a vacuum deposition method and a sputtering method, an electroplating method, an electroless plating method, a wet plating method such as a displacement plating method, and the like. It can be formed by the method. Among these methods, in particular, according to a wet plating method such as an electroplating method, an electroless plating method, and a displacement plating method, a desired palladium film is formed by a simple method without requiring a complicated apparatus. be able to. In particular, according to the electroplating method, a palladium film can be formed efficiently at low cost. Further, in the displacement plating method, a palladium film can be formed on a copper material by a simple treatment that is simply immersed in a plating bath for a short time, thereby obtaining a sufficient effect.

  The thickness of the palladium film is not particularly limited, and even a very thin Pd film formed by a displacement plating method can provide a sufficient effect, but is usually preferably about 0.001 to 5 μm, more preferably about 0.01 to 1 μm.

  Also, the method for forming the silver film is not particularly limited, and it can be formed by any method such as a vapor deposition method such as a vacuum deposition method or a sputtering method, a wet plating method such as an electroplating method or an electroless plating method. . Among these methods, in particular, according to a wet plating method such as an electroplating method or an electroless plating method, a target silver film can be formed by a simple method without requiring a complicated apparatus. When forming by electroplating, strike plating may be performed using a silver cyanide plating bath or the like, or a known bright silver plating film, matte silver plating film or the like may be formed. As for the silver plating bath for forming these silver plating films, known plating baths can be used as appropriate. There is no particular limitation on the thickness of the silver film, but usually a sufficient effect can be obtained by setting the film thickness to about 0.01 μm or more, and considering economics, etc., about 0.01 to 0.5 μm. And it is sufficient.

A nickel film or a nickel alloy film is formed on the palladium film or the silver film. The method for forming the nickel film and the nickel alloy film is not particularly limited, and any method such as a vapor deposition method such as a vacuum deposition method and a sputtering method, a wet plating method such as an electroplating method and an electroless plating method can be applied. . Also in this case, according to a wet plating method such as an electroplating method or an electroless plating method, a target nickel film or nickel alloy film can be formed by a simple method without requiring a complicated apparatus. When the nickel film is formed by a plating method, the kind of the nickel plating bath is not limited, and a known electro nickel plating bath such as a nickel sulfamate plating bath, a watt bath, a watt bath to which a brightener is added can be used.

  Examples of nickel alloy plating film include Ni-P alloy plating film, Ni-B alloy plating film, Ni-W alloy plating film, Ni-Mo alloy plating film, Ni-WP alloy plating film, Ni-Mo-P alloy A plating film etc. can be illustrated. The Ni content in these nickel alloy plating films is not particularly limited. For example, a nickel alloy plating film having a Ni content of about 60% by weight or more can be suitably used.

  A preferable example of the nickel alloy plating film includes a Ni-P alloy plating film. The phosphorus content in the Ni-P alloy plating film is usually preferably about 1 to 13% by weight, more preferably about 3 to 10% by weight.

  There is no particular limitation on the method for forming the Ni-P alloy plating film, and various conventional Ni-P alloy plating baths such as an electric Ni-P alloy plating bath and an electroless Ni-P alloy plating bath are used. Accordingly, a Ni—P alloy plating film may be formed on the copper or copper alloy used as the base material.

An example of the composition and plating conditions of the electric Ni—P alloy plating bath is as follows.
(1) Plating bath composition Nickel sulfate 200-400 g / L,
Nickel chloride 30-60 g / L,
Boric acid 30-50 g / L,
Phosphorous acid 1-10g / L
(2) Plating conditions pH 1.0 to 4.5, bath temperature 40 to 60 ° C, current density 1 to 3 A / dm ²
By performing electric Ni—P alloy plating under the above conditions, a Ni—P alloy plating film having a phosphorus content in the range of about 2 to 10% can be formed.

  As the electroless Ni—P alloy plating bath, a known electroless Ni—P alloy plating bath containing hypophosphite as a reducing agent can be used.

  Among these, in particular, an Ni—P alloy plating film can be efficiently formed by using an electric Ni—P alloy plating bath.

  The thickness of the nickel film or nickel alloy film is not particularly limited, but is usually preferably about 1 to 10 μm, more preferably about 2 to 5 μm.

  In the copper-based material of the present invention, the type of the surface layer is not particularly limited. For example, in a circuit portion made of a copper-based material of a printed wiring board having a surface layer such as Au or Pd, copper or copper as a base material It is possible to effectively prevent copper atoms contained in the alloy from diffusing into the surface layer.

  In particular, for a copper-based material having a silver film as a surface layer, copper atoms can be prevented from diffusing into the silver film on the surface and the reflectance of the silver film being lowered. For example, when a copper-based material with a silver film formed as a surface layer is used as a reflective part of an LED lighting unit, a packaged LED illumination having an LED light emitting element and a reflective part with a silver film formed on the surface In the unit, the thermal diffusion of copper atoms in the reflecting portion is suppressed, and the reflectance is hardly lowered, and a high reflectance can be maintained for a long time.

  In this case, there is no particular limitation on the type of silver film to be formed on the surface of the reflective portion, and any arbitrary method such as a vapor deposition method such as a vacuum deposition method or a sputtering method, a wet plating method such as an electroplating method or an electroless plating method, etc. Can be formed by a method. For example, when forming by an electroplating method, after performing strike plating using a silver cyanide plating bath or the like, a silver plating film may be formed using a known silver plating bath, if necessary. The silver plating film may be either a bright silver plating film or a matte silver plating film.

  The thickness of the silver film as the surface layer is not particularly limited, but is usually about 0.1 to 10 μm.

  A copper-based material having a diffusion prevention layer having a structure in which a palladium film or a silver film and a nickel film or a nickel alloy film are sequentially laminated on the base material made of copper or copper alloy, and having a silver film as a surface layer FIG. 1 shows a schematic diagram of an example of an LED lighting unit having a reflecting portion. In this LED lighting unit, LED light-emitting elements are arranged on electrodes such as ceramics and glass via electrodes, and a reflecting part is provided to effectively use the light emitted around the LED light-emitting elements. .

  According to the copper-based material having the copper diffusion preventing layer of the present invention, it is possible to effectively prevent the copper atoms contained in the base material from diffusing into the surface layer for the material based on copper or a copper alloy. In particular, according to an LED lighting unit having a copper-based material with a silver film as a surface layer as a reflection part, thermal diffusion of copper atoms from the base material is suppressed, so that there is little decrease in reflectance, and high reflectance is maintained for a long time. Can be maintained.

It is the schematic of an example of an LED lighting unit.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Using a rolled copper plate (size 50 x 50 mm, thickness 0.3 mm) as an object to be plated, semi-glossy Pd plating was performed by electroplating in the steps shown in Table 1 below, followed by nickel plating, Silver plating was performed. The composition of the nickel plating bath used is shown in Table 2, and the composition of the silver plating bath is shown in Table 3 and Table 4. For Pd plating, the plating time is changed to form a semi-glossy Pd plating film with a thickness in the range of 0.006 to 0.114 μm. For silver plating, a glossy bath or matte bath is used to make the gloss A silver plating film or a dull silver plating film was formed.

  Among the samples in which the silver plating film was formed by the above-described method, the reflectance of light having a wavelength of 450 nm was measured for the sample in which the semi-gloss Pd plating film having a thickness of 0.1 μm was formed, and then 1000 in the air at 150 After heat treatment for a time, the reflectance of light having a wavelength of 450 nm was measured. For comparison, the reflectance was also measured in the same manner for the sample on which the bright silver plating film or matte silver plating film was formed, except that the semi-gloss Pd plating was not performed and the other methods were the same as in Example 1. did. The results are shown in Table 5 below.

  As is clear from the above results, when the Pd plating film and the nickel plating film were formed as the base of the silver plating film, the Pd plating film was not formed, compared with the case where only the nickel plating film was formed. It is clear that the decrease in reflectance after heat treatment is greatly suppressed. Therefore, in an LED lighting unit having a reflective part on which a silver plating film is formed, a Pd plating film is formed on copper or a copper alloy, a nickel plating film is formed, and then a silver plating film is formed. It can be seen that the thermal diffusion of copper atoms from is suppressed and a high reflectance can be maintained for a long time.

  Further, the reflectance of light having a wavelength of 450 nm was measured for a sample on which a bright silver plating film was formed among samples in which the film thickness of the Pd plating film was changed in the range of 0 to 0.114 μm. A heat treatment was carried out at 5 ° C. for 5 minutes, and then the reflectance of light having a wavelength of 450 nm was measured. The results are shown in Table 6 below.

  As is clear from the above results, when the Pd plating film of 0.006 μm or more is formed, the decrease in the reflectance after the heat treatment is greatly suppressed as compared with the case where the Pd plating film is not formed. it is obvious.

Example 2
In the treatment process described in Table 1 of Example 1, instead of semi-glossy Pd plating, a copper material was immersed in a hydrochloric acid solution (Pd concentration 100 ppm) of palladium chloride (PdCl ₂ ) at 30 ° C. for 10 seconds. Substitution Pd plating treatment was performed, and then a bright silver plating film was formed according to the steps described in Table 1.

  After measuring the reflectance of light with a wavelength of 450 nm, the sample was heat-treated in air at 380 ° C. for 5 minutes, and then the reflectance of light with a wavelength of 450 nm was measured. As a result, the reflectance before heat treatment was 87.1%, but after heat treatment was 88.6%. The increase in reflectance after the heat treatment seems to be due to the recrystallization of the Ag plating film caused by the heat treatment.

  On the other hand, the reflectance of light having a wavelength of 450 nm before and after the heat treatment was measured for the sample on which the bright silver plating film was formed in the same manner as the above method, except that the substitution Pd plating treatment was not performed. As a result, the reflectance before the heat treatment was 88%, but decreased to 50% after the heat treatment.

  From the above results, it can be seen that even when the Pd plating film is formed by the displacement plating method, the decrease in the reflectance after the heat treatment can be largely suppressed.

Example 3
In the processing steps described in Table 1 of Example 1, instead of semi-gloss Pd plating, a strike silver plating bath containing 2 g / L of silver cyanide and 100 g / L of potassium cyanide was used, the bath temperature was 25 ° C., and the current density was A silver plating film was formed at 1 A / dm ² . At this time, the silver plating time was changed in the range of 0 to 30 seconds. Thereafter, a bright silver plating film was formed according to the steps described in Table 1.

  After measuring the reflectance of light with a wavelength of 450 nm for these samples, heat treatment was performed in air at 380 ° C. for 5 minutes, and then the reflectance of light with a wavelength of 450 nm was measured. Table 7 below shows the relationship between the plating time and film thickness of the silver plating film formed as the base of the nickel sulfamate plating and the reflectance of light having a wavelength of 450 nm before and after the heat treatment. In addition, the film thickness of Ag plating is a value calculated as current efficiency of 100%.

As is clear from the above results, when silver plating is formed as a base for nickel sulfamate plating, a decrease in reflectance after heat treatment is greatly suppressed as compared to the case where silver plating is not formed. It is clear.

Claims (4)

In a material based on copper or copper alloy, a diffusion prevention layer having a structure in which a palladium film or silver film and a nickel film or nickel alloy film are sequentially laminated is formed on the substrate. A copper having an anti-diffusion layer for copper , wherein the material and the palladium film or silver film are in contact with each other, and the palladium film or silver film and the nickel film or nickel alloy film are in contact with each other System material. The copper-based material according to claim 1, which has a silver film as a surface layer. The copper-based material according to claim 2, wherein the copper-based material is a reflecting portion in the LED lighting unit. The LED illumination unit which has a reflection part which consists of a copper-type material of Claim 3, and an LED light emitting element.

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