TWI465592B - A Ni-plated metal plate, a welded structure, and a method for manufacturing a battery material - Google Patents

Description

Ni-plated metal plate, welded structure, and method for manufacturing battery material

The present invention relates to a method for producing a Ni-plated metal plate, a welded structure, and a battery material, which are used for a battery material such as a positive electrode cap.

Previously, a Ni-plated steel sheet was used as a casing (battery tank) or a positive electrode cap of a battery such as a Li ion secondary battery. For example, a technique of forming a battery case by performing matte nickel plating on the surface of a steel sheet and two-layer plating of a gloss nickel-cobalt alloy as an upper layer thereof has been developed (Patent Document 1). In addition, a technique of performing Ni plating and matt Ni plating on the surface of the substrate after performing Ni plating on the surface of the substrate has been developed (Patent Document 2).

Further, since the shape of the positive electrode cap is complicated and the amount of processing after plating is large, the nickel plated plating plate is processed into a positive electrode cap in advance, and then nickel plating is applied to cover the substrate (steel plate) exposed by the processing.

In addition, electrodes (positive or negative) of the battery are electrically connected to the battery case or the positive electrode cap via a current collecting tab or a metal part called an ear piece. Further, in order to obtain a reliable connection, the battery case or the positive electrode cap and the ear piece are fused by using a resistor which generates heat by electric resistance. Generally, a Ni plate is used as the current collecting tab, and when a Ni-plated steel sheet as a positive electrode cap is welded to a current collecting tab (Ni plate), a nugget (a portion to be melted and solidified) is formed in the welded portion. The two are firmly fused together.

Patent Document 1: International Publication WO2000/65671

Patent Document 2: Japanese Laid-Open Patent Publication No. 2001-279490

Further, since Ni is a high-priced product, the inventors of the present invention have studied the use of a Cu alloy plate instead of a Ni plate as a current collecting tab to reduce the cost. However, since the melting point of the Cu alloy is about 400 ° C lower than that of Fe or Ni, it is judged that if the Ni-plated steel sheet to be a positive electrode cap is welded, the Cu alloy sheet is melted and cannot be welded. Therefore, the present inventors attempted to diffuse the Ni-plated steel sheet and the Cu alloy sheet by lowering the temperature at the time of welding, and as a result, it became apparent that the gloss of the Ni-plated steel sheet was adversely affected by the gloss plating.

In other words, it is judged that when the positive electrode cap for performing the gloss nickel plating is welded to the ear piece made of a Cu alloy plate, cracks are formed in the gloss nickel plating layer, and the welding strength is lowered.

In other words, the present invention has been made to solve the above problems, and an object of the invention is to provide a Ni-plated metal plate, a welded structure, and a method for producing a battery material which are excellent in weldability.

The inventors of the present invention conducted various studies and found that when the surface of the substrate is plated with two Ni plating layers, cracking of the Ni plating layer can be prevented by controlling the impurity concentration in the Ni plating layer. And improve the weldability.

In order to achieve the above object, the Ni-plated metal sheet of the present invention is formed by forming a first Ni plating layer on a surface of a substrate made of a metal plate and forming a second Ni plating layer thereon, and the thickness of the second Ni plating layer. The average concentration of C and S in the second Ni plating layer from the surface to the depth of 0.4 μm is 1.0% by mass or less.

The total average concentration is preferably 0.2% by mass or less.

The total average concentration is preferably 0.1% by mass or less.

The total average concentration is preferably 0.05% by mass or less.

The total average concentration is preferably 0.025% by mass or less.

The total concentration of C and S at the depth of 1.0 μm from the surface of the second Ni plating layer is preferably 1.0% by mass or less.

The above substrate is preferably steel, an iron-based alloy, a copper-based alloy, a Ni-based alloy, or an aluminum-based alloy.

The Ni-plated metal plate of the present invention is preferably used for resistance welding of a copper alloy strip having a tin-plated layer on the surface.

The Ni-plated metal plate of the present invention is preferably used as a positive electrode cap for a battery, and the second Ni-plated layer is made of matt Ni.

In the method for producing a battery material according to the present invention, after the first Ni plating layer is plated on the surface of the substrate made of a metal plate, plastic processing is performed, and then the second Ni plating layer is plated, and the thickness of the second Ni plating layer is applied. The total concentration of the C concentration and the S concentration from the surface to the depth of 0.4 μm of the second Ni plating layer is 0.50 μm or more, and the total concentration is 1% by mass or less.

The above battery material is preferably a positive electrode cap.

In the welded structure system of the present invention, a Ni-plated metal layer is formed on the surface of the substrate made of a metal plate, and a Ni-plated metal layer is formed as a second Ni-plated layer of matt Ni plating, and tin plating is provided on the surface. The copper alloy strip of the layer is welded by the resistance of the second Ni plating layer.

In the welded structure of the present invention, it is preferable that the nugget is not present in the welded portion of the copper alloy strip and the Ni-plated metal plate.

The Ni-plated metal plate is preferably a positive electrode cap for a battery.

Preferably, the tin plating layer has a reflow tin plating layer.

Preferably, the substrate of the tin plating layer has a copper plating layer.

The copper alloy strip of the present invention is used in the above-described welded structure and has a tin plating layer on its surface.

The red brass strip of the present invention is used in the above-described welded structure and has a tin plating layer on its surface.

The Cu-Zn-Sn-based alloy strip of the present invention is used in the above-described welded structure and has a tin-plated layer on its surface.

The copper alloy strip of the present invention is used in the above-mentioned welded structure, and has a tin-plated layer on the surface and contains 1 to 40% by mass of zinc.

The copper alloy strip of the present invention is used in the above-mentioned welded structure, and has a tin-plated layer on the surface, contains 1 to 20% by mass of zinc, and contains 0.1 to 1.0% by mass of tin.

According to the present invention, when two layers of Ni are plated on the surface of the substrate, cracking of the Ni plating layer can be prevented, and the weldability can be improved.

Hereinafter, a Ni-plated metal plate according to an embodiment of the present invention will be described. In the present invention, the term "%" means mass% unless otherwise specified.

In the Ni-plated metal plate according to the embodiment of the present invention, a first Ni-plated layer is formed on the surface of the substrate, and a second Ni-plated layer is formed thereon.

[substrate]

The substrate may be a metal plate, and particularly preferably a copper plate, an iron-based alloy, a copper-based alloy, a Ni-based alloy, or an aluminum-based alloy. For example, a steel sheet such as SPCD (JIS G 3141 cold-rolled steel sheet for extension processing and steel strip) is preferable.

Further, the thickness of the substrate is not particularly limited, and is generally 0.03 to 1.50 mm, preferably 0.05 to 1.00 mm, more preferably 0.05 to 0.80 mm. More preferably, it is 0.08 to 0.50 mm, and most preferably 0.15 to 0.40 mm.

[1st Ni-plated layer]

The first Ni plating layer functions as a base plating layer for protecting the substrate, and is usually formed by matt Ni plating, semi-gloss Ni plating, or gloss Ni plating. The thickness of the first Ni plating layer may be, for example, 0.1 to 10 μm.

The matt Ni plating can be plated in a well-known matt Ni plating bath (for example, a Watt bath, a high chloride bath, a perchlorination bath, a boron fluoride bath, a normal temperature bath, a double salt bath, a high sulfate bath). form. Known conditions can also be applied to the plating conditions.

Further, the semi-gloss Ni plating can be appropriately added to a known semi-gloss Ni plating bath (for example, a known semi-gloss agent (a polyoxyethylene adduct of an unsaturated alcohol, an unsaturated carboxylic acid) is appropriately added to a matt Ni plating bath such as a Watt bath. Formed by formaldehyde, hydrated chloral, fumarin, coumarin, etc.). Known conditions can also be applied to the plating conditions.

Further, as the gloss Ni plating, a known gloss Ni plating bath (for example, a sulfuric acid bath, an aminesulfonic acid bath, a Weisberg bath, a sulfonic acid gelatin bath, a sulfonic acid stepmarin bath) may be used. Plating is performed by a Weissberg eclectic bath, a saccharin butyne bath, and a bath in which a gloss is added to a matt plating bath. Known conditions can also be applied to the plating conditions.

[2nd Ni-plated layer]

The second Ni plating layer is formed on the outermost surface of the Ni-plated metal plate, and is welded to the welding target via the second Ni plating layer. Here, when the second Ni plating layer is formed by gloss plating of Ni, cracks are generated in the plating layer, and the fusion is strong. Degree is reduced. The reason for this is considered to be that a gloss agent in a plating bath is incorporated in the gloss Ni plating layer, and the gloss agent is heated and evaporated during welding to embrittle the plating layer.

Therefore, the second Ni plating layer can be formed by matt Ni plating, a semi-gloss Ni plating which reduces the proportion of the semi-gloss agent, or a gloss Ni plating which reduces the proportion of the gloss agent. As the semi-gloss agent, for example, a semi-gloss agent of about 0.0001 to 1.0 g/L or less can be added to the Ni plating bath. Further, as the glossing agent, for example, a primary glossing agent of about 0.01 to 5 g/L or a secondary glossing agent of about 0.0001 to 1.0 g/L may be added to the Ni plating bath.

As the semi-gloss agent, a polyoxyethylene adduct of an unsaturated alcohol, an unsaturated carboxylic acid formaldehyde, chloral hydrate, a formalin, a coumarin, an unsaturated carboxylic acid, a 1,4-butynediol, or the like can be used. By.

As the primary brightener, a saturated or unsaturated aliphatic sulfonate, an aromatic sulfonate, an inorganic compound (for example, sodium 1,5-naphthalenedisulfonate, 1, A known person such as sodium 3,6-naphthalene disulfonate, o-benzene sulphonimide (saccharin), cobalt sulfate, and the like. As the secondary brightener, an organic compound having an unsaturated group (for example, ethylene cyanohydrin, gelatin, formalin (formaldehyde), 1,4-butynediol, coumarin, nickel formate, etc.) can be used. Or known as inorganic substances such as metals (cadmium, zinc, sulfur, selenium, etc.).

The matt Ni plating can be plated in a well-known matt Ni plating bath (for example, a Watt bath, a high chloride bath, a perchlorination bath, a boron fluoride bath, a normal temperature bath, a double salt bath, a high sulfate bath). form.

Moreover, when the Ni-plated metal plate of the present invention is a positive electrode cap of a battery, After the first Ni plating layer is plated, the plastic processing such as press processing is performed to form a positive electrode cap, and the second Ni plating layer is plated to cover the material exposed by the processing.

Therefore, in order to protect the substrate and ensure the weldability, the thickness of the second Ni plating layer must be 0.50 μm or more. When the thickness of the second Ni plating layer is less than 0.50 μm, the weldability is lowered, and the material exposed by the processing cannot be sufficiently covered to deteriorate the corrosion resistance, the appearance, and the like. The upper limit of the thickness of the second Ni plating layer is not particularly limited, and in terms of cost, 10.0 μm can be set as an upper limit.

The thickness of the second Ni plating layer is preferably 0.7 to 5.0 μm, more preferably 0.8 to 5.0 μm, still more preferably 1.0 to 5.0 μm, still more preferably 1.2 to 4.0 μm, still more preferably 1.5 to 4.0 μm. The best is 1.8~4.0 μm.

As described above, when the second Ni plating layer is formed by gloss plating of Ni, cracks are formed in the plating layer during welding, and the welding strength is lowered. Therefore, the concentrations of C and S in the second Ni plating layer are controlled. . C and S are elements which are formed by decomposition of the gloss agent.

Specifically, the total average concentration of C and S from the surface to the depth of 0.4 μm of the second Ni plating layer is controlled to 1.0% by mass or less. When the total average concentration is more than 1.0% by mass, cracks may occur in the second Ni plating layer during welding to lower the welding strength. Here, the "total average concentration" is determined by measuring the C and S concentrations in the depth direction by glow discharge mass spectrometry (GD-MS method).

Specifically, as shown in FIG. 1 , by glow discharge mass spectrometry (GD-MS method), respectively, at a specific depth (a~f) of the second Ni-plated layer from the surface to a depth of 0.4 μm. Determine the concentration of C and S, and calculate at each point The total concentration of C and S at a~f. Further, the value obtained by weighting and averaging the sum of the total concentrations of C and S of the respective points a to f at the total depth x (μm) of each point a to f is "the surface of the second Ni plating layer from the surface to the depth of 0.4 μm. And S total average concentration". For example, in the case of Fig. 1, by {(C, S total concentration (% by mass)) + (C, S total concentration (% by mass) of point b)} × (distance between points a and b) (μm))/2, and the area S1 of the trapezoid between a and b which is the adjacent point among the points a to f is obtained. Similarly, the area S2 of the trapezoid between b and c; the area S3 of the trapezoid between c and d; the area S4 of the trapezoid between d and e; and the area S5 of the trapezoid between e and f are obtained. Further, "(S1 + S2 + S3 + S4 + S5) / total depth X (μm)] "the total average concentration of C and S from the surface of the second Ni plating layer to a depth of 0.4 μm" was calculated.

Further, the point a is the closest measurement point to the surface of the second Ni-plated layer, and the point f is the closest measurement point from the surface of the second Ni-plated layer at a depth of 0.4 μm.

The preferred value of each dot interval is 0.0006 to 0.10 μm.

Further, by measuring the average concentration of C and S at each point of the second Ni plating layer from the surface to the depth of 0.4 μm by the above method, the average concentration of C and S is totaled, and the second Ni plating layer can be calculated. The total average concentration of C and S from the surface to a depth of 0.4 μm.

The total average concentration of C and S in the second Ni plating layer from the surface to the depth of 0.4 μm is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and most preferably 0.035% by mass or less. . In addition, the lower limit of the total average concentration is not particularly limited, and since the total average concentration is excessively lowered, the cost is increased. Therefore, 0.0001% by mass can be used as the lower limit.

The total concentration of C and S at the position where the depth of the second Ni plating layer is 1.0 μm from the surface is preferably 1.0% by mass or less. The reason for this is that the substance formed by decomposing the gloss agent in the vicinity of the surface of the second Ni-plated layer at a depth of 1.0 μm is diffused to the joint portion during welding, and the weld strength is affected. Therefore, it is necessary to control the C at the depth. S total concentration.

Specifically, as shown in FIG. 1 , the specific depth (a to f) at a depth of 1.0 ± 0.05 μm from the surface of the second Ni plating layer is measured by glow discharge mass spectrometry (GD-MS method). The concentration of C and S was calculated, and the total concentration of C and S at each point a to f was calculated. Further, the value obtained by weighting and averaging the sum of the total concentrations of C and S at each of the points a to f is the "the thickness of the second Ni plating layer from the surface of the second plating layer is 1.0 μm. The total concentration of C and S in the position". For example, in the case of Fig. 1, by {(C, S total concentration (% by mass)) + (C, S total concentration (% by mass) of point b)} × (distance between points a and b) (μm))/2, and the area S1 of the trapezoid between a and b which is the adjacent point among the points a to f is obtained. Similarly, the area S2 of the trapezoid between b and c; the area S3 of the trapezoid between c and d; the area S4 of the trapezoid between d and e; and the area S5 of the trapezoid between e and f are obtained. In addition, (the total concentration of C and S at the position where the second Ni plating layer is 1.0 μm from the surface) is calculated by (S1 + S2 + S3 + S4 + S5) / total depth X (μm).

Further, the point a is the measurement point closest to the surface at a depth of 0.95 μm from the surface of the second Ni plating layer, and the point f is the closest measurement point at a depth of 1.05 μm from the surface of the second Ni plating layer.

The preferred value of each dot interval is 0.0006 to 0.050 μm.

Moreover, the depth from the surface of the second Ni plating layer is respectively determined by the above method. When the concentration of C and S at each point of the 1.0 μm position is measured, the concentration of C and S is totaled, and the total concentration of C and S at the position where the second Ni plating layer is 1.0 μm from the surface can be calculated.

The Ni-plated metal sheet of the present invention is suitable for use in a resistance welding of a second Ni-plated layer toward a welding target material. As described above, by controlling the total concentration of C and S in the second Ni plating layer, it is possible to prevent the C and S from causing cracks in the second Ni plating layer due to the heat action at the time of resistance welding.

The welding target is not particularly limited, and various metal plates (steel plates, etc.) can be used, but tin-plated copper alloy is particularly preferable. As the copper alloy, a copper alloy having various compositions can be used without particular limitation, and examples thereof include phosphor bronze, Carson alloy, brass, red brass, white copper, titanium copper, and other copper alloys.

In the present invention, the term "phosphor bronze" refers to a copper alloy containing copper as a main component and containing Sn and a P having a small mass. For example, phosphor bronze has a composition containing 3.5 to 11% by mass of Sn, 0.03 to 0.35% by mass of P, and the balance being composed of copper and unavoidable impurities.

In the present invention, the "Carson alloy" refers to a copper alloy in which an element (for example, any one of Ni, Co, and Cr) which forms a compound with Si is added, and which is precipitated as a second phase particle in the parent phase. For example, the Carson alloy has a composition containing 1.0 to 4.0% by mass of Ni, 0.2 to 1.3% by mass of Si, and the balance being composed of copper and unavoidable impurities. As another example, the Carson alloy has a composition containing 1.0 to 4.0% by mass of Ni, 0.2 to 1.3% by mass of Si, 0.03 to 0.5% by mass of Cr, and the balance being composed of copper and unavoidable impurities. In another example, the Carson alloy has 1.0 to 4.0% by mass of Ni, 0.2 to 1.3% by mass of Si, and 0.5 to 2.5 mass. The amount of Co is the same, and the remainder is composed of copper and unavoidable impurities. In another example, the Carson alloy has 1.0 to 4.0% by mass of Ni, 0.2 to 1.3% by mass of Si, 0.5 to 2.5% by mass of Co, and 0.03 to 0.5% by mass of Cr, and the balance is copper and The composition of the inevitable impurities. Further, in another example, the Carson alloy has a composition containing 0.2 to 1.3% by mass of Si, 0.5 to 2.5% by mass of Co, and the balance being composed of copper and unavoidable impurities.

Other elements (for example, Mg, Sn, B, Ti, Mn, Ag, P, Zn, As, Sb, Be, Zr, Al, and Fe) may be optionally added to the Carson alloy. In general, these other elements are added in total to about 2.0% by mass. For example, in another example, the Carson alloy has 1.0 to 4.0% by mass of Ni, 0.2 to 1.3% by mass of Si, 0.01 to 2.0% by mass of Sn, and 0.01 to 2.0% by mass of Zn, and the remainder is The composition of copper and unavoidable impurities.

In the present invention, brass refers to an alloy of copper and zinc, and particularly refers to a copper alloy containing 20% by mass or more of zinc. The upper limit of the zinc is not particularly limited, and may be 60% by mass or less, preferably 45% by mass or less, or 40% by mass or less.

In the present invention, the term "red brass" means an alloy of copper and zinc, and means a copper alloy containing 1 to 20% by mass of zinc, more preferably 1 to 10% by mass of zinc. Further, the red brass may contain 0.1 to 1.0% by mass of tin.

In the present invention, the term "white copper" refers to a copper alloy containing copper as a main component and containing 60% by mass to 75% by mass of copper, 8.5% by mass to 19.5% by mass of nickel, and 10% by mass to 30% by mass of zinc.

In the present invention, the term "titanium copper" refers to copper as a main component and contains Ti1.0. Copper alloy with a mass of % to 4.0% by mass. For example, titanium copper has a composition containing 1.0 to 4.0% by mass of Ti, and the remainder is composed of copper and unavoidable impurities. As another example, titanium copper has a composition containing 1.0 to 4.0% by mass of Ti, 0.01 to 1.0% by mass of Fe, and the balance being composed of copper and unavoidable impurities.

In the present invention, the other copper alloy refers to one or more of Zn, Sn, Ni, Mg, Fe, Si, P, Co, Mn, Zr, Cr, and Ti in a total amount of 8.0% or less, and the remainder A copper alloy partially composed of unavoidable impurities and copper.

In the present invention, it is preferred to use red brass as the copper alloy.

Further, the thickness of the copper alloy is not particularly limited and may be generally 0.03 to 1.50 mm, preferably 0.05 to 1.00 mm, more preferably 0.05 to 0.80 mm, still more preferably 0.08 to 0.50 mm, and most preferably 0.10. ~0.30 mm.

Further, it is preferable to form tin plating of 0.1 to 3.0 μm on the surface (welding surface) of the copper alloy. Further, tin plating is preferably performed by reflow processing. Further, copper plating having a thickness of 0.05 to 1.0 μm can be used as a base plating for tin plating. Further, nickel plating having a thickness of 0.01 to 1.0 μm may be applied as a base plating for copper plating.

Next, an example of a method for producing a battery material for a Ni-plated metal plate to which the present invention is applied will be described. First, the first Ni plating layer is plated on the surface of the substrate made of a metal plate, and then plasticized, and then the second Ni plating layer is plated. Here, the thickness of the second Ni plating layer is 0.5 μm or more, and the total concentration of the C concentration and the S concentration of the second Ni plating layer from the surface to the depth of 0.4 μm is 1% by mass or less.

The first Ni plating layer and the second Ni plating layer have been described. The plastic working is not particularly limited, and examples thereof include known processes such as press working, DI (draw and ironing) processing, drawing processing, and shrinking processing.

Further, as the material for the battery, a battery case (can) and a positive electrode cap are exemplified, and a positive electrode cap is particularly preferable.

Example

[Manufacture of Ni-plated metal sheets]

After the substrate was subjected to usual pretreatment (electrolytic degreasing and pickling treatment) using SPCD (JIS G 3141 cold-rolled steel sheet) having a thickness of 0.30 mm, the first Ni-plated layer was plated on the surface of the substrate. Thereafter, the substrate was punched into a disk shape, and pressed into a positive electrode cap shape as shown in FIG. Furthermore, the portion of the pressing section of the positive cap is R = 0.6 mm. Further, the positive electrode cap was pressed so that the first Ni plating layer side became the convex side.

Then, the second Ni plating layer was plated on the first Ni plating layer of the positive electrode cap of FIG. The composition and plating thickness of the first Ni plating layer and the second Ni plating layer are shown in Tables 1 and 2. In the description of Table 1, "gloss" indicates the following gloss Ni plating, "matt" indicates the following matte Ni plating, and "half gloss" indicates the following semi-gloss Ni plating.

Further, the gloss Ni plating is used for a Watt bath (NiSO ₄ .7H ₂ O: 190-290 g/L, NiCl ₂ .6H ₂ O: 15 to 75 g/L, H ₃ BO ₃ : 15 to 45 g/ L, the remaining part is water) Adding 1,5-naphthalene disulfonate (DNS) 7.0~9.0 g/L, 1,4-butynediol (BD) 0.15~0.25 g/L Come on. Further, the conditions for the gloss plating were carried out at a current density of 1 to 5 A/dm ² and a liquid temperature of 35 to 55 °C.

Matte Ni plating using Watt bath (NiSO ₄ .7H ₂ O: 190~290 g/L, NiCl ₂ .6H ₂ O: 15~75 g/L, H ₃ BO ₃ : 15~45 g/L, remaining Part of the water) matt plating bath. Further, the matte plating conditions were carried out at a current density of 1 to 5 A/dm ² and a liquid temperature of 35 to 55 °C.

Semi-gloss Ni plating is used for Watt bath (NiSO ₄ .7H ₂ O: 190~290 g/L, NiCl ₂ .6H ₂ O: 15~75 g/L, H ₃ BO ₃ : 15~45 g/L, The remainder is water)) Adding fumarin: a semi-gloss plating bath of 1.0 to 2.5 g/L. Further, the semi-gloss plating conditions were carried out at a current density of 1 to 5 A/dm ² and a liquid temperature of 35 to 55 °C.

In Tables 1 and 2, when the second Ni plating layer is formed, the gloss agent concentration "-" indicates matt Ni plating. Further, when the second Ni plating layer is formed, the amount of DNS and BD added to the gloss Ni plating bath is as described in Tables 1 and 2 regarding the gloss plating of Ni.

Further, inventive examples 1-27 and 1-2 of Table 1 were obtained by plating the first Ni plating layer, and then heating at 790 ° C for 20 seconds in an N ₂ atmosphere to make one of the first Ni plating layers The Fe-Ni diffusion layer is left and the remaining portion of the first Ni plating layer is left as a Ni recrystallized layer. Thereafter, the film was punched into a disk shape in the same manner as in the other examples, and after the press working, the second Ni plating was performed.

[Manufacture of tin-plated copper alloy strips]

A tin-plated copper alloy strip welded to the above-described Ni-plated metal plate was produced in the following manner. First, after a normal pretreatment (electrolytic degreasing and pickling treatment) of a copper alloy substrate having a thickness of 0.15 mm (composition shown in Table 3), Cu plating was performed at a thickness of 0.3 μm, and a thickness of 1.0 μm was applied to Cu plating. It The Sn is plated and finally the reflow process is performed.

The Cu plating bath is coated with Cu at 40-80 g/L of sulfuric acid, 170-230 g/L of copper sulfate, the remainder is water, the bath temperature is 20~30 °C, and the current density is 3.0-5.0 A/dm ² . .

Sn plating bath is 30~50 g/L of stannous sulfate, 40~80 g/L of sulfuric acid, 30~50 g/L of cresol sulfonic acid, 1~5 g/L of gelatin, 0.5~1.5 g of β-naphthol / L, the remaining part is water, plating bath temperature: 20 ~ 30 ° C, current density: 1.0 ~ 1.5 A / dm ² under the implementation of Sn plating. Further, the thickness of the Sn plating is adjusted by the plating time (when the plating time is 2 minutes, the thickness of the Sn layer before the reflow process is about 1 μm). The reflow treatment was carried out by inserting the sample into a heating furnace adjusted to nitrogen (oxygen of 1 vol% or less) at 400 ° C for 15 to 20 seconds and performing water cooling.

For each sample thus obtained, the following characteristics were evaluated.

(1) The average concentration of C and S in the second Ni-plated layer from the surface to a depth of 0.4 μm

It was measured using a glow discharge mass spectrometer (manufactured by VG Micro Trace, model VG9000). As described in the specific measurement method (see Fig. 1), 8 points are measured in the depth direction in the range of 0 to 0.40 μm in depth, and the interval between the points is set to be about 0.04 to 0.06 μm. In addition, it is considered that when the measurement interval of each point exceeds 0.1 μm, the measurement variation of the measurement site in the depth direction becomes large.

When the interval between points is set to about 0.04 to 0.06 μm, if the measurement deviation is large, the measurement interval can be further reduced and the measurement point can be increased (for example, measurement interval: 0.001 to 0.02 μm, measurement point: 20) ~400 Point, etc.).

When a foreign matter such as an organic film adheres to the surface of the sample, it is immersed in acetone for ultrasonic cleaning or acid washed with dilute sulfuric acid, and then washed with water to remove foreign matter.

(2) The total concentration of C and S in the second Ni-plated layer from the surface at a depth of 1.0 μm

It was measured using the same glow discharge mass spectrometer as described above.

As described in the specific measurement method (see Fig. 1), three points are measured in the depth direction in the range of depth of 0.95 to 1.05 μm, and the interval between the points is set to be about 0.04 to 0.06 μm. In addition, it is considered that when the measurement interval of each point exceeds 0.1 μm, the measurement variation of the measurement site in the depth direction becomes large.

When the interval between points is set to about 0.04 to 0.06 μm, if the measurement deviation is large, the measurement interval can be further reduced and the measurement point can be increased (for example, measurement interval: 0.001 to 0.02 μm, measurement point: 5) ~100 points, etc.).

Further, when a foreign matter such as an organic film is adhered to the surface of the sample, the foreign matter is removed by ultrasonic cleaning by immersion in acetone or pickling with dilute sulfuric acid followed by washing with water.

(3) The thickness of the first Ni plating layer and the thickness of the second Ni plating layer

The thickness of the first Ni plating layer was measured using a fluorescent X-ray film thickness meter (Model SFT5100, manufactured by SII Corporation).

In addition, the total thickness of the first Ni plating layer and the second Ni plating layer was measured using a fluorescent X-ray film thickness meter (Model SFT5100, manufactured by SII Co., Ltd.), and then the thickness of the second Ni plating layer was calculated by the following formula.

Thickness (μm) of the second Ni plating layer = (thickness (μm) of the total of the second Ni plating layer and the first Ni plating layer) - (thickness (μm) of the first Ni plating layer)

Furthermore, the thickness of the first Ni plating layer and the second Ni plating layer can also be observed by magnifying the cross section of the plating layer (for example, SIM (Scanning Ion Microscope) photographed by FIB (Focused Ion beam). The ion microscope is measured like (10,000 to 30,000 times).

(4) Welding strength

The second Ni plating layer of the Ni-plated metal plate is overlapped with the tin-plated surface of the tin-plated copper alloy strip, and a resistance welding power source (Miyachi Technos transistor-type resistance welding power supply MDB-4000B (product name)) is used to apply pressure 30 N, the welding current is 4.0 kA, the welding time is 10 msec, and the diameter of the welding electrode is 3 mm. The resistance welding of the series point method (series point welding) is performed. The fusion point is 2 points. Further, as long as the electrode spacing is in the range of 10 to 25 mm at the time of welding, the welding can be performed in the same manner without any particular problem. For the sample after welding, a precision load measuring machine (MODEL-1310VR: product name) manufactured by Aikoh Engineering Co., Ltd. was used to perform tensile test by peeling off the Ni-plated metal plate and the tin-plated copper alloy (test speed 10 mm/ Minutes), and the weld strength was measured.

When the welding strength is 15 N or more, the weldability is excellent.

(5) Whether there is a nugget

The presence or absence of the nugget was determined by observing the cross section of the welded portion of the Ni-plated metal plate and the tin-plated copper alloy bar with an optical microscope (100 times). When the short diameter of the molten solidified portion is 0.05 mm or more, it is determined that there is a nugget. The short diameter of the molten solidified portion is the largest circular diameter included in the molten solidified portion.

Further, in the present embodiment, it was found that the weld strength was obtained even without the nugget. Although the reason is not clear, it is considered that Ni is diffused into the tin-plated layer of the tin-plated copper alloy strip by Ni in the Ni-plated metal sheet to form a Ni-Cu-Sn alloy layer to obtain a fusion strength.

The results obtained are shown in Tables 1 to 3. In addition, the welding target material No of the welding of Table 1 and Table 2 corresponds to Table 3. Further, Table 2 shows the results of the influence of the composition of the copper alloy as the welding target material to be welded.

As is apparent from Table 1, in the case of the respective examples in which the total concentration of the C and S in the second Ni plating layer from the surface to the depth of 0.4 μm is 1.0% by mass or less, the welding strength is 15 N or more, and the weldability is excellent.

When the second Ni plating layer is used in the case where the total concentration of C and S at a depth of 1.0 μm from the surface is 1.0% by mass or less, in the case of Examples 1-7 to 1-24 and 1-26 to 1-32. Compared with the other examples in which the thickness of the second Ni plating layer is the same, the welding strength is increased by 5% or more. For example, when Examples 1-1 and 1-13 having the same thickness of the second Ni plating layer were compared, the welding strength of Example 1-13 was 5% or more.

Further, the thicker the thickness of the second Ni plating layer, the higher the welding strength tends to be.

Further, as is apparent from Table 2, in the case of the respective embodiments in which the total concentration of the C and S in the second Ni plating layer from the surface to the depth of 0.4 μm is 1.0% by mass or less, even if the copper alloy to be welded is a different composition, The welding strength is also 15 N or more, and the weldability is excellent. Particularly in the case where the welding target is a Cu-Zn-Sn-based alloy, the welding strength is high.

On the other hand, in the case of Comparative Examples 1-1, 1-2, 1-4, and 1-5 in which the thickness of the second Ni plating layer was less than 0.5 μm, the fusion strength was lowered to less than 15 N, and the weldability was poor. The reason for this is that the first Ni-plated layer is oxidized to reduce the weldability of the first Ni-plated layer itself after the first Ni-plated layer is plated. Therefore, the upper layer is the second Ni-plated layer. If the thickness is thin, the weldability cannot be improved.

When the second Ni plating layer is plated, the amount of the brightening agent is increased, that is, in the case of Comparative Examples 1-3, 1-5, and 1-6, the average of the second Ni plating layer from the surface to the depth of 0.4 μm of C and S is averaging. The concentration exceeds 1% by mass, and the weldability is poor or cannot be welded. The reason for this is considered to be that gas is generated from the second Ni plating layer due to C and S in the second Ni plating layer at the time of welding.

3 and 4 are cross-sectional views showing the welded structures of the Ni-plated metal sheets 2 and the copper alloy strips 4 of Examples 1 to 24 and Comparative Example 1-3, respectively. It is understood that in the case of the embodiment 1-24, although the nugget is not formed in the vicinity of the interface S between the Ni-plated metal plate 2 and the copper alloy strip 4, the weld strength is still high.

On the other hand, in the case of Comparative Example 1-3, cracks C were generated in the Ni plating layer 2a of the Ni-plated metal plate 2. Furthermore, the symbol 2b of Figure 4 Indicates the substrate (SPCD).

2‧‧‧Ni plating metal plate

2a‧‧‧Ni plating

2b‧‧‧Substrate

4‧‧‧copper alloy strip

S‧‧‧ interface

Fig. 1 is a view showing a calculation method of the total average concentration of C and S.

Fig. 2 is a view showing the shape of a positive electrode cap which is subjected to press working after plating a first Ni plating layer on the surface of the substrate in the embodiment.

Figure 3 is a cross-sectional view showing a welded structure of a Ni-plated metal plate and a copper alloy strip of Examples 1-24.

Fig. 4 is a cross-sectional view showing a welded structure of a Ni-plated metal plate and a copper alloy strip of Comparative Example 1-3.

2‧‧‧Ni plating metal plate

4‧‧‧copper alloy strip

S‧‧‧ interface

Claims (20)

A Ni-plated metal plate is formed by forming a first Ni-plated layer on a surface of a substrate made of a metal plate and forming a second Ni-plated layer thereon, wherein the thickness of the second Ni-plated layer is 0.50 μm or more. Further, the total concentration of C and S in the second Ni plating layer from the surface to the depth of 0.4 μm is 1.0% by mass or less, and the Ni-plated metal sheet is used for resistance welding of a copper alloy strip having a tin plating layer on the surface. The Ni-plated metal plate according to Item 1 of the patent application, wherein the total average concentration is 0.2% by mass or less. The Ni-plated metal plate according to Item 1 of the patent application, wherein the total average concentration is 0.1% by mass or less. The Ni-plated metal plate according to Item 1 of the patent application, wherein the total average concentration is 0.05% by mass or less. The Ni-plated metal plate according to Item 1 of the patent application, wherein the total average concentration is 0.035 mass% or less. The Ni-plated metal sheet according to any one of the first to fifth aspects of the present invention, wherein the second Ni-plated layer has a total concentration of C and S at a depth of 1.0 μm from the surface of 1.0% by mass or less. The Ni-plated metal sheet according to any one of claims 1 to 5, wherein the substrate is steel, an iron-based alloy, a copper-based alloy, a Ni-based alloy, or an aluminum-based alloy. A Ni-plated metal plate according to any one of claims 1 to 5, which is used as a positive electrode cap for a battery, and the second Ni-plated layer is matt Ni. A method for producing a battery material is characterized in that a first Ni plating layer is plated on a surface of a substrate made of a metal plate, and then plastic working is performed, and then a second Ni plating layer is plated, and the thickness of the second Ni plating layer is The total concentration of the C concentration and the S concentration in the second Ni plating layer from the surface to the depth of 0.4 μm is 1% by mass or less. The method for producing a battery material according to claim 9, wherein the battery material is a positive electrode cap. A welded structure is a Ni-plated metal plate in which a first Ni-plated layer is formed on a surface of a base material made of a metal plate and a second Ni-plated layer of matt Ni plating is formed thereon, and tin plating is provided on the surface. The copper alloy strip of the layer is formed by resistance welding through the second Ni plating layer. The fusion bonded structure of claim 11, wherein the nugget is not present in the welded portion of the copper alloy strip and the Ni-plated metal plate. The welded structure according to claim 11 or 12, wherein the Ni-plated metal plate is a positive electrode cap for a battery. The fusion bonded structure of claim 11 or 12, wherein the tin plating layer has a reflow tin plating layer. The fusion bonded structure of claim 11 or 12, wherein the base of the tin plating layer has a copper plating layer. A copper alloy strip for use in the welded structure of any one of claims 11 to 15 and having a tin plating layer on the surface. A red brass strip used to apply for patents Nos. 11-15 A welded structure according to any one of the preceding claims, which has a tin plating layer on the surface. A Cu-Zn-Sn-based alloy strip for use in the welded structure according to any one of claims 11 to 15, which has a tin-plated layer on the surface. A copper alloy strip for use in the welded structure according to any one of claims 11 to 15, which has a tin-plated layer on the surface and contains 1 to 40% by mass of zinc. A copper alloy strip for use in a welded structure according to any one of claims 11 to 15, which has a tin-plated layer on the surface, contains 1 to 20% by mass of zinc, and contains 0.1 to 1.0% by mass of tin. .