TW201515313A - Conductive member - Google Patents

Abstract

The present invention provides a conductive member having exceptional cost performance, low contact resistance, and exceptional corrosion resistance, the conductive member being capable of being used highly reliably for a long period of time. A conductive member provided with a Ni-plated film and a noble-metal-plated film on the surface of a metallic substrate, the conductive member being characterized in that the Ni-plated film contains 10 mass% or more phosphorus (P), and the noble-metal-plated film includes one or more noble metals selected from the group comprising Pd, Pt, Rh, Ir, Os, and Ru, is amorphous or microcrystalline, and has a thickness of 20 nm and over to less than 200 nm.

Description

Conductive member

This invention relates to a conductive member which is provided with a noble metal plating film on a surface of a metal substrate via a Ni plating film.

In recent years, as one of the considerations of environmental energy, fuel cells are attracting attention. In a fuel cell, an electrolyte membrane is sandwiched between a pair of electrodes formed by an anode and a cathode, and a plurality of fuel cell unit cells in which a separator is disposed are laminated on the anode side and the cathode side, respectively. A collector plate is provided at both ends of the lamination direction of the unit cell laminate to take out current.

In the current collector plate, for example, in order to efficiently collect current, a small contact resistance is required, and a current collector plate having a gold plating (Au) is used for the surface of a metal substrate (for example, see Patent Document 1). ~3). However, with the widespread use of fuel cells, how to reduce the cost has become a major issue, and there is a desire to suppress the use of expensive Au plating films as much as possible. In particular, this tendency has become more apparent as the price of gold has risen in recent years.

However, the Au plating film that has been installed in the past is generally When the thickness of the thinned layer is about 0.1 μm to 1 μm, there is a problem that the metal substrate is corroded or the contact resistance with the separator is increased. Moreover, even if the film thickness of the Au plating film is ensured, the contact resistance of the current collector plate increases with the use of the fuel cell.

Therefore, the present inventors have proposed a current collector plate in which an Au plating film is formed via a crystal-plated noble metal film (see Patent Document 4). That is, the present inventors have found that the corrosion of the metal substrate or the increase in the contact resistance of the collector plate is caused by the oxidation of the Ni plating film provided on the substrate, and the noble metal plating film is used as the crystalline substance by utilizing and plating Ni. The substitution reaction of Ni of the film forms an Au plating film, and the grain boundary of the plated noble metal film is blocked by Au. By suppressing the oxidation of Ni, it is possible to prevent the corrosion of the metal substrate or the increase in the contact resistance, and it is possible to realize a collector plate which is excellent in reliability over a long period of time and which can be used even if the Au plating film is thinned compared with the prior art. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-217644 (paragraph 0056)

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2008-78104 (paragraph 0090)

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2008-146866 (paragraph 0027)

[Patent Document 4] Japanese Laid-Open Patent Publication No. 2013-105629 (Request) 2)

Au is characterized by being chemically stable, excellent in corrosion resistance, less change in contact resistance value with time, and excellent in solderability, and is mainly composed of a current collector plate of a fuel cell, for example, a lead frame or a bus bar (Bus) Bar), a printed wiring board, a connection terminal, etc., many of which use a conductive member provided with an Au plating film. However, due to the high price in recent years, the ideal is to minimize the use.

Therefore, the inventors of the present invention have been able to suppress the contact resistance and the corrosion resistance of the conductive member without using the Au plating film, and have found that the Ni plating film is amorphous or microcrystalline by the repeated investigation. The combination of the precious metal plating film solves the problems of the above, and the conductive member which can satisfy both cost and quality is obtained, and the present invention has been completed.

Accordingly, an object of the present invention is to provide a conductive member which is excellent in cost reliability, has small contact resistance, and is excellent in corrosion resistance and can be used with good reliability over a long period of time.

In other words, the present invention provides a conductive member having a noble metal plating film on a surface of a metal substrate via a Ni plating film, wherein the Ni plating film contains 10% by mass or more of phosphorus (P), and the noble metal plating layer is further provided. The film comprises a material selected from the group consisting of Pd, Pt, Rh, Ir, Os, and Ru. Any one or more of the noble metals (more specifically, a platinum group) are amorphous or microcrystalline, and have a film thickness of 20 nm or more and less than 200 nm.

The conductive member of the present invention is provided with a Ni plating film containing phosphorus (P) in an amount of 10% by mass or more in terms of P element. The phosphorus-containing film having 10% by mass or more is contained in order to obtain a Ni plating film having excellent corrosion resistance, and the Ni plating film has an amorphous crystal structure. More excellent corrosion resistance can be exhibited by increasing the content of phosphorus, and it is preferable to contain 11% by mass or more. However, when it is formed by, for example, electroless Ni plating, it is generally used as, for example, hypophosphorous acid or secondary. The reducing agent such as sodium phosphite, in addition to the Ni plating solution, increases the concentration of the reducing agent in the plating solution, and the phosphorus content of the Ni plating film tends to increase to about 15%, but even increases to The concentration of the above reducing agent is lower than that of the Ni plating rate, and it is no longer possible to obtain phosphorus in the Ni plating film. Since it is difficult to increase the phosphorus content to 15% or more, the phosphorus content of the Ni plating film is substantially The upper limit is 15% by mass. In addition, when it is formed by electrolytic plating, the Ni-plating bath is used in a plating bath in which a phosphorous acid is added to a Watt bath, which is generally used, and has a phosphorus content of about 10% by mass. The film becomes amorphous. The addition of citric acid or the like may increase the phosphorus content to about 25% by mass, but when the phosphorus content exceeds 15% by mass, the hydrogen current is excessively reduced, and the current efficiency of Ni plating is extremely lowered, even in the case of In the case of electrolytic plating treatment, the upper limit of the phosphorus content in the Ni plating film is 15% by mass.

For the film thickness of this Ni-plated film, the table from the metal substrate The surface may be 1 μm or more and 10 μm or less, and preferably 3 μm or more and 8 μm or less, from the viewpoint of depositing a Ni plating film in a uniform thickness. Even if the film thickness of the Ni plating film is thicker than 10 μm, the effect is saturated, and the cost is increased.

Further, in the conductive member of the present invention, the amorphous material or micro-particles of the noble metal selected from the group consisting of Pd, Pt, Rh, Ir, Os, and Ru are provided on the Ni plating film. Crystalline plated precious metal film. The noble metal plating film has a crystal structure having an amorphous or microcrystalline state, prevents diffusion of Ni from the Ni plating film of the lower layer, and prevents an increase in contact resistance or a decrease in corrosion resistance. In other words, when the noble metal plating film is crystalline, there is a tendency for Ni to diffuse through the crystal grain boundary. In particular, when used in a high-temperature and high-humidity environment, such as a collector plate of a fuel cell, Ni is thermally diffused and easily oxidized, or further hydrated to form insulating NiO or NiO (H ₂ O), in addition to making contact. In addition to the reduction in electrical resistance, it also makes it difficult to ensure corrosion resistance. Here, the amorphous or microcrystalline plated noble metal film means that the lattice point is not clearly observed by the observation of the electron beam diffraction image by a transmission electron microscope (TEM). That is, in the case where the plating film is crystalline, the lattice points in the electron beam diffraction image can be clearly confirmed, and in the case of microcrystalline matter, the lattice dots become unclear and amorphous. Next, the lattice point can be discriminated because the unconfirmed diffraction pattern becomes a halo pattern. In addition, the measurement conditions are based on the examples described later. Also, the same applies to the previously described Ni plating film.

In order to become amorphous or microcrystalline, the noble metal plating film is formed. For example, an amorphous or microcrystalline material can be obtained by depositing a noble metal film containing an eutectoid element to form an amorphous or microcrystalline material, or by relatively increasing the current density during electrolytic plating treatment. . In particular, since a large amount of metal and a wide range of eutectoid composition range are formed, it is easy to form amorphous plating, and it is preferable that the noble metal plating film is made of phosphorus (P) or boron (B) in a manner of containing 2% by mass or more. Any one or more of the eutectoid elements in the group of tungsten (W) may be used, and more preferably a non-crystalline or microcrystalline plated noble metal film containing 2% by mass or more of phosphorus (P).

Here, as for the content of the eutectoid element in the noble metal plating film, if the content thereof is increased, the crystal structure of the plated noble metal film can be more reliably made amorphous or microcrystalline. When the content of the eutectoid element is high, for example, when the noble metal plating film is formed by electroless plating, when the content of the eutectoid element is increased by more than 5%, the hardness of the plated noble metal film is increased, and heat treatment is performed. When the crack is more likely to occur, the upper limit of the content of the eutectoid element in the noble metal plating film can be said to be substantially 5% by mass.

Further, in the present invention, the thickness of the plated noble metal film is 20 nm or more and less than 200 nm, preferably 25 nm or more and less than 150 nm. In other words, when the film thickness of the noble metal plating film is less than 200 nm, the contact resistance as the conductive member can be suppressed. Further, when the film thickness of the plated noble metal film is thinner than 20 nm, a uniform plated noble metal film cannot be deposited on the Ni plating film, and diffusion of Ni cannot be prevented.

In the present invention, the means for forming the Ni plating film and the noble metal plating film may be electrolytic plating treatment or electroless plating. The treatment is preferably formed by electroless plating treatment from the viewpoint of cost or uniformity of film thickness. Further, the Ni plating film and the noble metal plating film may be provided on the front and back sides of the metal substrate in accordance with the use of the conductive member, or may be provided only on one side.

In the present invention, the base material of the metal is, for example, a copper alloy such as copper or brass, or a base material such as aluminum or aluminum alloy, iron or stainless steel such as stainless steel, but is excellent in light weight and excellent in workability. From the viewpoints of electrical conductivity, high thermal conductivity, and relatively low cost, it is preferably an aluminum substrate composed of aluminum or an aluminum alloy. Further, when the Ni plating film and the noble metal plating film described above are plated on only one surface of the substrate, the standard oxidation-reduction potential E ⁰ (25° C.) of each metal shown below can be used. It is understood that in the case of an aluminum substrate, for example, even if it is exposed to a wet atmosphere in the use of a fuel cell, since Al is the most basic metal, Al which is not exposed in the plating state is preferentially oxidized. That is, it is assumed that even when the Ni plating film is exposed to an oxidizing atmosphere by plating a noble metal film, Al acts as a sacrificial anode, and electrons are supplied to the Ni plating film to suppress oxidation of the Ni plating film.

Here, the aluminum or aluminum alloy used for the aluminum substrate is not particularly limited, and examples thereof include high-purity aluminum (JIS H4170; 1N99), or Various aluminum alloys such as A1100, A3003, A5052, A5005, A5652, A6063, A6061, A6101, and AA5252. Among them, from the viewpoint of corrosion resistance, formability, strength, and cost, a 5000-series aluminum alloy is suitable.

Further, when an aluminum substrate is used, the aluminum substrate is previously immersed in a zinc immersion bath to form a zinc substitution bath, and the Ni plating film can be formed by a zinc substitution layer formed on the aluminum substrate. To form. Here, as the zinc immersion bath, for example, an aqueous zinc oxide base solution containing 4.1% by mass of zinc oxide and 25% by mass of sodium hydroxide can be used to dilute it to 400 ml/L with ion-exchanged water, and the immersion temperature is 15 to 30 ° C. Left and right, the immersion time is about 10 seconds to 3 minutes. Further, from the viewpoint of forming a denser zinc-substituted layer, a zinc-impregnated bath is temporarily immersed to form a substituted zinc layer on the surface of the aluminum substrate, and then immersed in an acid bath to remove the substituted zinc layer, which can be immersed in zinc impregnation again. Bath to form a replacement zinc layer. As the acid bath at this time, for example, the acid is nitric acid, sulfuric acid, hydrochloric acid or the like, and an acid aqueous solution having a concentration of 10 to 65% by mass can be used, the immersion temperature is about 15 to 30 ° C, and the immersion time is about 10 seconds to 1 minute.

Further, before the zinc substitution treatment, the aluminum substrate may be pretreated by a known method such as degreasing treatment or desmut treatment, or a connection terminal or the like may be formed on the aluminum substrate by press working. Processing. Further, after forming a plated noble metal film, washing with water, drying, or the like, a conductive member according to the present invention can be obtained.

The conductive member of the present invention is excellent in corrosion resistance and can suppress an increase in contact resistance even after long-term use. Therefore, to fuel As the battery, for example, various conductive members such as a lead frame or a bus bar, a printed wiring board, and a connection terminal can be used. In particular, since the diffusion of Ni can be prevented even in a high-temperature and high-humidity environment, it has been suitable for forming a conductive member of a fuel cell, which is suitable as a collector plate.

According to the present invention, in particular, it is possible to provide a conductive member which is not provided with an Au plating film, has low contact resistance, is excellent in electrical conductivity, and is excellent in corrosion resistance and long-term durability. Therefore, the conductive member of the present invention can simultaneously satisfy cost and quality, and can be used with good reliability over a long period of time.

1‧‧‧Electrical components

2‧‧‧Aluminum substrate

3‧‧‧Replace the zinc layer

4‧‧‧Ni plating

5‧‧‧Pd coated film

6‧‧‧Upper board

7‧‧‧Comparative board

8‧‧‧ Lower board

Fig. 1 is an electron beam diffraction image of a Pd-plated film of the test conductive member obtained in Example 1.

Fig. 2 is a schematic cross-sectional view for explaining a conductive member of the present invention.

3] FIG. 3 is a TEM image (magnification: 9,900 times) showing a cross section of a Ni plating film and a Pd plating film of the conductive member for testing obtained in Example 1. FIG.

4] FIG. 4 is a TEM image (magnification: 285,000 times) showing a cross section of a Pd-plated film of the test conductive member obtained in Example 1. FIG.

[Fig. 5] Fig. 5 is a view for explaining measurement of contact resistance of a conductive member for testing Schematic diagram of the situation [(a) side view, (b) perspective view].

Fig. 6 is an electron beam diffraction image of a Pd-plated film of the test conductive member obtained in Example 3.

Fig. 7 is a TEM image (magnification: 9,900 times) showing the cross-sectional appearance of a Ni plating film and a Pd plating film of the test conductive member obtained in Example 3.

8] FIG. 8 is a TEM image (magnification: 285,000 times) showing the cross-sectional appearance of a Pd-plated film of the test conductive member obtained in Example 3. FIG.

9] Fig. 9 is an electron beam diffraction image showing a Ru plating film of the test conductive member obtained in Example 4. [Fig.

Fig. 10 is a TEM image (magnification: 9,900 times) showing the cross-sectional appearance of a Ni plating film and a Ru plating film of the conductive member for testing obtained in Example 4.

[Fig. 11] Fig. 11 is a TEM image (magnification: 285,000 times) showing the cross-sectional appearance of the Ru plating film of the test conductive member obtained in Example 4.

Fig. 12 is an electron beam diffraction image of a Pd-plated film of the test conductive member obtained in Comparative Example 2.

Fig. 13 is a TEM image (magnification: 9,900 times) showing the cross-sectional appearance of a Ni plating film and a Pd plating film of the test conductive member obtained in Comparative Example 2.

[Fig. 14] Fig. 14 is a TEM image showing the cross-sectional appearance of a Pd-plated film of the test conductive member obtained in Comparative Example 2 (magnification: 285,000) Double).

Hereinafter, embodiments suitable for the present invention will be specifically described based on examples and comparative examples. In the examples and comparative examples, the analysis of each of the obtained plating films, the determination of the crystallinity, and the various physical properties of the test conductive members were evaluated by the methods described later. The pooled results are shown in Table 1.

[Examples] (Example 1) [Production of conductive member for test]

An aluminum substrate having a size of 30 mm × 60 mm × 3 mm in thickness was cut out from an aluminum alloy A5052-H34 material having a thickness of 3 mm, and was immersed in a diluted alkaline degreaser (trade name: Topalclean 161 manufactured by Okuno Pharmaceutical Co., Ltd.). The mixture was added to an aqueous solution having a concentration of 30 g/L, and degreased and washed at 55 ° C for 5 minutes. After washing with water, an etchant (trade name: Top Al soft 108, manufactured by Okuno Pharmaceutical Co., Ltd.) containing 35 mass% of sodium hydroxide was immersed in an aqueous solution diluted to a concentration of 50 g/L, and etched at 55 ° C for 30 seconds. . Next, after washing with water, the decontamination liquid containing nitric acid (trade name: Topdesmut N-20, manufactured by Okuno Pharmaceutical Co., Ltd.) was diluted into an aqueous solution having a concentration of 100 ml/L, and decontaminated at 25 ° C for 1 minute. deal with.

Then, after washing, the one-side surface and the outer peripheral end of the aluminum substrate are A mask is used, and a zinc treatment liquid (trade name: Subster Zn-111, manufactured by Okuno Pharmaceutical Co., Ltd.) containing 20% by mass of sodium hydroxide and 3.6 mass% of zinc oxide is used as a zinc impregnated to a concentration of 500 ml/L. The bath was immersed in the aluminum substrate at 22 ° C for 30 seconds. After washing with water, an aqueous solution of nitric acid having a concentration of 62% by mass was used as an acid bath, and the aluminum substrate was immersed at 25 ° C for 30 seconds to peel off the substituted zinc layer temporarily formed on the surface of the aluminum substrate. After washing with water, the above-mentioned zinc dip bath was again used, and the aluminum substrate was immersed at 22 ° C for 30 seconds, and a zinc substitution treatment was performed so as to form a substituted zinc layer of about 1 μm.

Next, after washing with water, a Ni plating bath (which is a product containing 19% by mass of sodium hypophosphite and 3.9% by mass of acetic acid (trade name: Top NICORON RCH-MLF, manufactured by Okuno Pharmaceutical Co., Ltd.), and 36% by mass of sulfuric acid is used. Ni-plated Ni liquid (trade name: Top NICORON RCH-1LF) was diluted with water to a concentration of 130 ml/L and 40 ml/L, and the two were mixed, and impregnated at 90 °C. Electroless Ni plating was performed for 35 minutes. Thereby, a Ni plating film having a film thickness of 4.7 μm was formed on one side surface of the aluminum substrate opposite to the masked surface. In addition, the Ni plating film contains 11% by mass of phosphorus (P) in terms of P element, and the crystal structure is amorphous, based on the analysis and evaluation of the plating film to be described later and the determination of the crystallinity.

After the Ni plating film was formed as described above and washed with water, prepreg was performed by immersing in 35 mass% hydrochloric acid at 25 ° C for 30 seconds. Furthermore, a chemical (manufactured by Okuno Pharmaceutical Co., Ltd., trade name: ICP Axela) containing 18% by mass of hydrochloric acid and 0.04% by mass of a palladium salt is used as water at 200 ml/L. The diluted catalyst bath was immersed at 30 ° C for 1 minute. After washing with water, a Pd-plated bath containing 13% by mass of the wrong agent (trade name: Top Pallas PDP-M, manufactured by Okuno Pharmaceutical Co., Ltd.), 7.2% by mass of palladium salt, and 5.6% by mass of a wrong agent were used. Pharmacy (trade name: Top Pallas PDP-A), 41% by mass of phosphate (product name: Top Pallas PDP-B), 7 mass% sodium hydroxide, 0.29 mass% Pharmaceutical agent (trade name: Top Pallas PDP-C, manufactured by the company), drug containing 44% by mass of phosphate (trade name: Top Pallas PDP-D, manufactured by the company), containing 17% by mass of ethylenediamine, 16% by mass A drug of 0.1% by mass of a sulfur-containing compound (trade name: Top Pallas PDP-E, manufactured by the company) was diluted with water to a concentration of 200 ml/L, 12 ml/L, 70 ml/L, 30 ml/L, and 3.5 ml/ L, 100 ml / L, and these were mixed, and immersed for 8 minutes at 57 ° C to perform electroless plating Pd treatment. Thereby, a Pd plating film (a noble metal plating film) having a film thickness of 49 nm was formed on the Ni plating film. In addition, according to the analysis and evaluation of the plating film to be described later and the determination of the crystallinity, the Pd-plated film contains 2% by mass of phosphorus (P) in terms of P element, and the crystal structure is amorphous. In Fig. 1, an electron beam diffraction image (halo pattern) of the TEM obtained by this Pd plating film is shown.

Further, after the electroless plating Pd treatment, it is washed with water and further dried by hot washing. As shown in FIG. 2, it is provided with a Ni plating film on the one side surface of the aluminum substrate 2 via the replacement zinc layer 3. 4. The Pd film 5 was plated to obtain the test conductive member 1 of Example 1. In addition, the amount of the treatment liquid such as the plating bath used in each of the above steps is 2L in total. get on.

In Fig. 3, the test conductive member 1 obtained in the first embodiment shows the result of observation by a transmission electron microscope (TEM) (magnification: 9,900 times). Here, after forming a protective film of a resin on the surface of the Pd-plated film 5, a cross section of the Ni plating film and the Pd plating film was observed by a FIB (bundled ion beam) method. It has also been confirmed from the observation of the cross-sectional image that the Ni-plated film and the Pd-coated film have a uniform color tone and can be seen as amorphous. Moreover, FIG. 4 is a TEM image in which the cross section of the Pd-plated film was observed at 285,000 times. In this TEM image, it was not confirmed that there was a clear crystal lattice, and it was found that the Pd-plated film was amorphous.

[Analysis and evaluation of plating film]

Here, each of the film thicknesses of the Ni plating film and the noble metal plating film of the test conductive member 1 obtained above was measured using a fluorescent X-ray film thickness meter (Fisher scope XDVμ manufactured by Fisher Instruments).

Further, the content of phosphorus (P) in the Ni plating film is measured by preparing a Ni-plated bath similar to the above-described user and depositing it on the Cu plate (it is easy to scatter the fluorescent X-ray by Al due to heavy element Cu). The measurement was carried out by a fluorescent X-ray apparatus (RIX2100 manufactured by Rigaku Corporation) and quantitative analysis of the P content rate by the FP method (Fundamental parameter method). Further, in the plating of the noble metal film, the phosphorus (P) content was measured, except that the Ni plating (Ni-B plating) containing B was deposited on the Cu plate, and the same Pd bath was used as the above-mentioned user. Plating Pd, and In the case of the Ni plating film, the P content ratio was also quantitatively analyzed by the FP method of the fluorescent X-ray apparatus. However, in Example 4 to be described later, the Cl element content from barium chloride was quantitatively analyzed by the FP method of EPMA.

[Determination of crystallinity of plating film]

In addition, when the crystallinity of the Ni plating film and the noble metal plating film of the test conductive member 1 was determined, the cross section of the test conductive member 1 was plated by a Quanta 3D type concentrated ion beam processing apparatus (FIB) manufactured by FEI. A sample of the sample was attached with a carbon protective film, and the observation site was taken out and fixed on a copper grid, and the film was processed into a thickness of 100 nm as an observation sample. Further, observation and image acquisition were performed under the condition of an acceleration voltage of 200 kV by an electron microscope (TEM) by Tecnai G2 F20 S-TWIN manufactured by FEI. Due to the noble metal plating film used for TEM observation, the film thickness is about 100 nm, and the electron beam diffraction region of the aperture having a diameter of 200 nm is restricted to obtain an electron beam diffraction image of only the target region (restricted-field electron beam diffraction image). The way to adjust the viewing conditions. In addition, when it is confirmed that the obtained electron beam diffraction image lattice point is clear, it is determined to be crystallized, and when the lattice point is unclear, it is judged to be microcrystalline, and it is confirmed that it is not a lattice point but is confirmed. In the case of the halo pattern, it was judged to be amorphous.

[Contact resistance measurement]

With respect to the test conductive member obtained above, the contact resistance was measured as follows. As shown in Fig. 5 (a), the plated noble metal film side was brought into contact with the comparative plate 7 and held between the upper plate 6 and the lower plate 8, and the surface pressure was applied from the up and down direction, and the test conductive member 1 was measured. Contact resistance value. In general, it is known that the contact resistance obtained in the collector plate of a fuel cell is assumed to be 10 mΩ when the surface pressure is 1 MPa. About cm ² , the contact resistance of the test conductive member 1 obtained above is about 0.05 mΩ when the surface pressure is 1 MPa. Cm ² represents an extremely good contact resistance. Further, the upper plate 6, the comparative plate 7, and the lower plate 8 are respectively made of a 30 mm-60 mm-thickness-thickness-thick aluminum plate (A5052 material) on both sides of the front and back sides with a film thickness of 5 μm and a film thickness of 0.1 μm. In the Au plating film, as shown in Fig. 5 (b), the contact resistance measurement samples in which the longitudinal and lateral directions overlap each other are prepared, and the contact area S between the test conductive member 1 and the comparison plate 7 is set to 3 mm × 3 mm. =9cm ² . Further, the contact resistance (mΩ.cm ² ) was such that a current I of ^{2 A} was passed between the upper plate 6 and the lower plate 8, and the voltage V between the test conductive member 1 and the comparative plate 7 was measured, and R (mΩ. Cm ² )=V×S/I=V×9/2 is obtained.

[Anode polarization test]

The anode for the test was conducted in the same manner as described above, and the anode polarization test was carried out as follows. First, the conductive member for shielding test was exposed to have an electrode area of 1 cm ² as a working electrode (WE). Further, a saturated calomel electrode (SCE) was used as a reference electrode (RE), and platinum was used as a counter electrode (CE). These were immersed in a 5 mass% sulfuric acid aqueous solution (30 ° C), and a potentiostat (Beidou Electric Co., Ltd.) was used. The system HZ-3000) became an anode polarization at a scanning speed of 20 mV/min. Further, in the obtained current potential curve, the anode current at a voltage of 1 V was obtained. Since the plating film having good corrosion resistance is low in anode current, when it is 1 mA/cm ² or less, it is judged as ○, and if it is not, it is judged as ×.

[Nitrate aeration test]

The test conductive member obtained in the same manner as described above was subjected to a nitric acid aeration test in accordance with JIS-H8620 Appendix 1. First, for the sake of caution, the surface of the plated noble metal film was removed by ethanol, and after drying, 5 ml of nitric acid was placed in the bottom of the dryer having a volume of 2 L, and the obtained test conductive member was placed on the magnetic plate. Cover it on top. Then, the test conductive member was used in this example except that the test conductive member was taken out and then washed with water and dried, and the presence or absence of corrosion occurred was visually confirmed. , there is no confirmed corrosion point. Further, in the following examples and comparative examples, the corrosion point was found to be ○ for every 5 cm ² of the test conductive member, and it was judged to be ○ if there were five or more.

(Example 2)

The test conductive member of Example 2 was obtained in the same manner as in Example 1 except that the immersion time of the Pd-plated bath was performed for 14 minutes and the electroless plating Pd treatment was performed. The obtained conductive member for testing has a Ni plating film having a phosphorus content of 11% by mass and a film thickness of 5.2 μm, and has a Pd film having a phosphorus content of 2% by mass and a film thickness of 87 nm, and plating of either one. The crystal structure of the film is amorphous. With respect to the test conductive member of the second embodiment, when the contact resistance was measured in the same manner as in Example 1, the contact resistance was the same as in Example 1 when the surface pressure was 1 MPa. Further, other evaluations were carried out in the same manner as in the first embodiment. The results are shown in Table 1.

(Example 3)

The test conductive member of Example 3 was obtained in the same manner as in Example 1 except that the electroless plating Pd treatment was carried out as follows. That is, in the third embodiment, a Pd-plated bath (which is a pharmaceutical product containing 2.5% by mass of ethylenediamine and 4.0% by mass of palladium salt (trade name: Muden noble PD-1, manufactured by the company), and 11% by mass is used. Sub-phosphite agent (commercial name: Muden noble PD-2), a drug containing 2.1% by mass of ethylenediamine, 6.0% by mass of hypophosphite, and 5.4% by mass of a wrong agent (trade name of the company: Muden noble PD-3) was diluted with water to a concentration of 50 ml/L, 50 ml/L, and 100 ml/L, and mixed, and immersed at 55 ° C for 2 minutes to perform electroless plating. Pd processing.

Thus, the conductive member for the test of Example 3 was provided with a Ni plating film having a phosphorus content of 11% by mass and a film thickness of 5.3 μm, and a Pd film having a phosphorus content of 5% by mass and a film thickness of 53 nm. Any of the plating films has a crystalline structure which is amorphous. Fig. 6 shows an electron beam diffraction image (halo pattern) of a TEM obtained by plating a Pd film. Further, in the test conductive member of the third embodiment, when the contact resistance was measured in the same manner as in the first embodiment, the contact resistance was the same as in the first embodiment when the surface pressure was 1 MPa. Further, other evaluations were carried out in the same manner as in the first embodiment. The results are shown in Table 1.

Further, the obtained conductive member for the test was subjected to a cross-sectional observation by a transmission electron microscope (TEM) (magnification: 9,900 times). After a protective film of a resin was formed on the surface of the Pd-plated film, a cross section of the Ni plating film and the Pd plating film was observed by a FIB (bundled ion beam) method. The results are shown in Fig. 7. Even from the observation of the cross-sectional image, it has been found that any of the Ni-plated and Pd-coated films is not amorphous, and any of them is amorphous. Further, Fig. 8 is a TEM image in which the cross section of the Pd-plated film was observed at 285,000 times. In this TEM image, it was not confirmed that there was a clear crystal lattice, and it was found that the Pd-plated film was amorphous.

(Example 4)

The test conductive member of Example 4 was obtained in the same manner as in Example 1 except that a noble metal plating film composed of a rhodium-plated (Ru) film was formed as follows. In the same manner as in the first embodiment, a Ni-plated film was formed and washed with water, and the degreasing bath prepared by diluting the degreaser (trade name: Ace Clean 801, manufactured by Okuno Pharmaceutical Co., Ltd.) into water at 50 g/L at 50 ° C was used. The degreasing treatment was carried out by immersing for 5 minutes. After the conductive member for the water-washing test, the degreaser (trade name: Top Cleaner E, manufactured by Okuno Pharmaceutical Co., Ltd.) was diluted with water to 50 ml/L, and sodium hydroxide was diluted with water to 50 g/L, and the two were mixed. The degreasing bath prepared was immersed at room temperature, and the anode current of 5 A/dm ² was subjected to an anode electrolytic degreasing treatment for 1 minute in the test conductive member. After washing with water, the test conductive member was immersed for 1 minute in a solution in which 35% by mass of hydrochloric acid was diluted with water to 200 ml/L, and the surface of the conductive member was activated, washed with water, and immersed in cerium chloride at 20 g/L. The 75 ° C rhodium plating bath was subjected to electrolytic plating of Ru by energizing the current of 1 A/dm ^{2 for} 2 minutes.

Thus, in the fourth embodiment, a Ni plating film having a phosphorus content of 11% by mass and a film thickness of 5.6 μm was provided, and a Ru plating film having a Cl content of 2.5% by mass and a film thickness of 93 nm was obtained. Conductive member. Among them, the crystal structure of the Ni plating film is amorphous. The crystal structure of the Ru plating film of the other is microcrystalline. In Fig. 9, an electron beam diffraction image of the TEM obtained by the Ru film is shown (the lattice dots are unclear).

In the test conductive member of the fourth embodiment, when the contact resistance was measured in the same manner as in Example 1, the contact resistance was the same as in Example 1 when the surface pressure was 1 MPa. Further, other evaluations were carried out in the same manner as in the first embodiment. The results are shown in Table 1.

Moreover, the obtained conductive member for testing is used for Cross-sectional observation of a transmission electron microscope (TEM) (magnification 9,900 times). After forming a protective film of a resin on the surface of the Ru plating film, a cross section of the Ni plating film and the Ru plating film was observed by a FIB (bundled ion beam) method. The results are shown in Fig. 10. According to the observation of the cross-sectional image, as compared with the Pd-coated film of Example 1 or Example 3, it was confirmed that the color of the Ru-coated film caused by the grain boundary was only slightly. In addition, FIG. 11 is a TEM image in which the cross section of the Ru plating film was observed at 285,000 times. By this, it was confirmed that the Ru plating film formed by the electrolytic plating treatment was composed of microcrystals having a crystal lattice region of about 5 to 10 nm.

(Comparative Example 1)

The same operation as in Example 1 was carried out except that the electroless Ni plating treatment was carried out as follows, except that the bath temperature of the Pd bath was set to 57 ° C and the immersion time was set to 8 minutes to carry out the electroless plating Pd treatment. The test conductive member of Comparative Example 1 was obtained. In the first comparative example, a Ni plating bath (which is a product containing 11% by mass of sodium hypophosphite and 24% by mass of a compounding agent (product name: ICP NICORON GSR-M) manufactured by Okuno Pharmaceutical Co., Ltd.), and The Ni plating solution containing 36% by mass of nickel sulfate (trade name: ICP NICORON GSR-1, manufactured by the company) was diluted with water to a concentration of 150 ml/L and 50 ml/L, and the two were mixed, and 80 was obtained. The electroless Ni plating treatment was performed by immersing for 30 minutes at °C.

Thus, the conductive member for the test of Comparative Example 1 was provided with a Ni plating film having a phosphorus content of 6 mass% and a film thickness of 5.1 μm, and a Pd plating having a phosphorus content of 2% by mass and a film thickness of 52 nm was obtained. skin membrane. Among them, the crystal structure of the Ni plating film is crystalline, and the crystal structure of the Pd plating film is amorphous. Further, the test conductive member of Comparative Example 1 was subjected to various evaluations in the same manner as in Example 1. As a result, although the contact resistance showed a good value, as shown in Table 1, the evaluation of corrosion resistance or durability was unsatisfactory.

(Comparative Example 2)

The test conductive member of Comparative Example 2 was obtained in the same manner as in Example 1 except that the electroless plating Pd treatment was carried out as follows. That is, in Comparative Example 2, a Pd-plated bath (a product containing a chelating agent (trade name: Pallatop LP-M, manufactured by Okuno Pharmaceutical Co., Ltd.) and a drug containing 7 mass% of palladium salt (product of the same company) were used. Name: Pallatop LP-A), a drug containing 41% by mass of a reducing agent (trade name: Pallatop LP-B, manufactured by the company), and a drug containing 4.4% by mass of a wrong agent (trade name: Pallatop LP-C) The electroless plating Pd treatment was carried out by diluting with water to a concentration of 200 ml/L, 20 ml/L, 70 ml/L, and 10 ml/L, and mixing them at 60 ° C for 10 minutes.

Thus, the conductive member for the test of Comparative Example 2 was provided with a Ni plating film having a phosphorus content of 11% by mass and a film thickness of 5.6 μm, and a Pd plating having a phosphorus content of 1% by mass and a film thickness of 63 nm was obtained. Membrane. Among them, the crystal structure of the Ni plating film is amorphous, and the crystal structure of the Pd plating film is crystalline. Fig. 12 shows an electron beam diffraction image of the TEM obtained by plating a Pd film (the lattice points are clear). And targeted The test conductive member of Comparative Example 2 was subjected to various evaluations in the same manner as in Example 1. As a result, although the contact resistance showed a good value, as shown in Table 1, the evaluation of corrosion resistance or durability was unsatisfactory.

Further, the obtained conductive member for the test was subjected to a cross-sectional observation by a transmission electron microscope (TEM) (magnification: 9,900 times) in the same manner as in the Example. As a result, as shown in Fig. 13, in the Pd-plated film, the color of the grain boundary caused by the crystal grain was confirmed, and it was confirmed that it had crystallinity. Further, Fig. 14 shows a TEM image in which the cross section of the Pd-plated film was observed at 285,000 times, and a region of the crystal lattice stripe pattern exceeding tens of nm was confirmed.

As is clear from the results of the above-described examples and comparative examples, any of the conductive members of the first to fourth embodiments of the present invention has a small contact resistance and excellent corrosion resistance and long-term durability. On the other hand, in the case of Comparative Example 1 in which the phosphorus-containing ratio of the Ni plating film was low, or in Comparative Example 2 in which the phosphorus-containing ratio of the Pd-plated film was low and the crystal structure was crystallized, the corrosion resistance was poor. Even though the corrosion point has been largely confirmed by the nitric acid aeration test, it is considered that it is not resistant to long-term users.

1‧‧‧Electrical components

2‧‧‧Aluminum substrate

3‧‧‧Replace the zinc layer

4‧‧‧Ni plating

5‧‧‧Pd coated film

Claims (10)

A conductive member comprising a conductive film having a noble metal plating film on a surface of a metal substrate via a Ni plating film, wherein the Ni plating film contains 10% by mass or more of phosphorus (P), and the noble metal plating layer The film contains a noble metal selected from the group consisting of Pd, Pt, Rh, Ir, Os, and Ru, and is amorphous or microcrystalline, and has a film thickness of 20 nm or more and less than 200 nm. The conductive member according to claim 1, wherein the noble metal plating film contains 2% by mass or more of an eutectoid element selected from the group consisting of phosphorus (P), boron (B), and tungsten (W). The conductive member according to claim 1 or 2, wherein the Ni plating film is amorphous. The conductive member according to claim 1 or 2, wherein the Ni plating film and the noble metal plating film are formed by electroless plating treatment. The conductive member according to claim 1 or 2, wherein the Ni plating film is formed by an electroless plating treatment, and the noble metal plating film is formed by electrolytic plating treatment. The conductive member according to claim 1 or 2, wherein the film thickness of the Ni plating film is 1 μm or more and 10 μm or less. The conductive member according to claim 1 or 2, wherein the metal substrate is an aluminum substrate composed of aluminum or an aluminum alloy. The electrically conductive member according to claim 7, wherein the Ni plating film is formed by a substitute zinc layer formed on the aluminum substrate. A conductive member according to claim 1 or 2, which is used in a fuel cell set In the electric panel, the fuel cell current collector plate is disposed on both end faces of a cell laminate in which a plurality of fuel cell unit cells are laminated, and an electric current is taken out. The conductive member of claim 1 or 2 is used in a bus bar.