JP2018129226A - Copper terminal material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper terminal material which allows the diffusion of copper from a base material made of copper or copper alloy to be effectively suppressed by a diffusion prevention layer laminated on the base material in a copper terminal material, and if a noble metal layer is provided thereon, allows the higher reliability to be kept.SOLUTION: A copper terminal material includes: a diffusion prevention layer formed on a base material made of copper or copper alloy and having a thickness of 0.1 μm or more and 10.0 μm or less; and a grain size-adjustment part formed in at least a part of the diffusion prevention layer and having an average crystal grain size of 0.3 μm or more. In the base material, a modified layer in which the content of metal in the diffusion prevention layer becomes 1.0 mass% or more is formed in a part bordering the grain size-adjustment part in a range of from a boundary face with the grain size-adjustment part to a thickness of 1 μm or more and 50 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a copper terminal material useful as a connector terminal used for connection of electrical wiring of automobiles and consumer devices, and a method for manufacturing the same.

  In general, a connector terminal used for connecting an electrical wiring of an automobile, a consumer device or the like is a copper terminal material obtained by plating a surface of a copper or copper alloy base material with tin, gold, silver or the like. Of these, terminal materials plated with noble metals such as gold and silver are excellent in heat resistance and are therefore suitable for use in high-temperature environments. Conventionally, terminal materials plated with such noble metals include those disclosed in the following patent documents.

  In Patent Document 1, there is an average crystal grain size of 0.3 μm or more between nickel, cobalt, zinc, copper, and alloys thereof between the conductive metal base and the noble metal layer. A noble metal covering material for electrical contacts in which a formation is formed is disclosed, and it is described that long-term reliability is high by suppressing diffusion of a base component in a high temperature environment. In this case, in order to control the crystal grain size of the underlayer, after the plating for the underlayer is performed on the substrate, heat treatment is performed under a predetermined condition, or rolling is performed at a predetermined processing rate. Yes.

JP2015-137421A

  However, in the invention described in Patent Document 1, an attempt is made to function as a diffusion preventing layer by enlarging the crystal grains of the underlayer and to improve the reliability of the contact having the noble metal surface. Therefore, further diffusion prevention technology of copper is desired.

  The present invention has been made in view of the above-mentioned problems, and a diffusion prevention layer is laminated on a base material made of copper or a copper alloy to effectively diffuse copper from the base material for a copper terminal material. An object of the present invention is to provide a copper terminal material that can be suppressed and can maintain high reliability when a noble metal layer is provided thereon.

  In the copper terminal material of the present invention, a diffusion prevention layer having a thickness of 0.1 μm or more and 10.0 μm or less is formed on a substrate made of copper or a copper alloy, and an average crystal is formed on at least a part of the diffusion prevention layer. A particle size adjusting portion having a particle size of 0.3 μm or more is formed, and a portion of the base material that is in contact with the particle size adjusting portion is 1 μm or more and 50 μm or less from the interface with the particle size adjusting portion. An altered layer is formed in which the metal content in the diffusion preventing layer is 1.0% by mass or more in the thickness range.

Since the average crystal grain size is enlarged to 0.3 μm or more in the grain size adjusting part of the diffusion preventing layer, there is an effect of reducing the copper diffusion path from the base material. In the deteriorated layer of the base material, the copper of the base material and the metal of the diffusion preventing layer are in solid solution, and accordingly, the concentration of copper is lowered accordingly. Since the diffusion rate between different metals is proportional to the concentration difference at the interface, the concentration difference can be reduced by the altered layer, and the diffusion of copper from the base material to the diffusion preventing layer can be suppressed. . Therefore, in the part where the particle size adjusting part and the altered layer are formed, it is possible to effectively suppress the diffusion of copper from the base material, and if a noble metal layer is formed thereon, the copper to the noble metal layer Diffusion can be prevented and the effect of improving heat resistance by the noble metal layer can be effectively exhibited.
In this case, if the deteriorated layer is less than 1% of the total thickness of the substrate, the copper diffusion suppressing effect is poor, and if it exceeds 5%, the material properties such as workability of the substrate may be impaired.

In the copper terminal material of the present invention, the diffusion prevention layer may be composed of one or more metal layers made of any one of nickel, nickel alloy, cobalt, and cobalt alloy.
By using these metal layers as diffusion preventing layers, it is possible to effectively prevent copper from diffusing from the base material. These metal layers may be a single layer, or two or more layers may be laminated to form an underlayer.

In the copper terminal material of the present invention, any one of gold, a gold alloy, silver, a silver alloy, palladium, a palladium alloy, platinum, a platinum alloy, rhodium, and a rhodium alloy is formed on the particle size adjusting portion in the diffusion preventing layer. It is preferable that a noble metal layer having a thickness of 0.1 μm or more and 5.0 μm or less is formed.
By forming these noble metal layers on the particle size adjusting portion in the diffusion preventing layer, the heat resistance as the terminal material can be effectively exhibited.

  In the method for producing a copper terminal material of the present invention, after forming a metal coating layer on the surface of the base material, the metal coating layer is irradiated by irradiating at least part of the surface of the metal coating layer with a laser beam. The portion irradiated with the laser light serves as the diffusion preventing layer serving as the particle size adjusting unit, and the deteriorated layer is formed on the base material in a portion in contact with the particle size adjusting unit.

In the above-mentioned patent document, heat treatment is performed after plating in order to enlarge the crystal grains of the underlayer. With such a method, the entire structure of the base material is enlarged and desired material characteristics cannot be obtained. There is a problem. Furthermore, in the method of rolling after plating, there is a problem that desired material properties of the substrate cannot be obtained because the structure of the substrate also changes.
In the method of the present invention, the metal coating layer is heated from the surface side by irradiation with laser light so that the crystal grains are enlarged. The crystal grains can be locally enlarged. For this reason, only the part which wants to suppress the spreading | diffusion of copper from a base material as a terminal can enlarge the crystal grain of a metal coating layer, and can form a deteriorated layer in a base material. Moreover, in the area | region which does not irradiate a laser beam, there is no possibility that the material characteristic of a base material may be changed, and material characteristics, such as desired workability as a copper terminal material, can be maintained.

In the method for producing a copper terminal material of the present invention, the laser beam may be a laser beam obtained from a solid laser, fiber laser, semiconductor laser, or gas laser and having a wavelength in the range of 400 nm to 11 μm.
By irradiating laser light having a wavelength in the above range with these lasers, the metal coating layer can be effectively enlarged.

  In the method for producing a copper terminal material of the present invention, after forming a metal coating layer on the surface of the substrate, the noble metal layer is formed on at least a part of the surface of the metal coating layer, and a laser is applied to the surface of the noble metal layer. By irradiating light, the metal coating layer is used as the diffusion preventing layer in which the portion irradiated with the laser light is the particle size adjusting portion, and the base material in the portion in contact with the particle size adjusting portion And forming the altered layer.

  In this case, as in the case of the method of irradiating the surface of the metal coating layer with laser light, the crystal grains of the metal coating layer are enlarged only in the portion where the noble metal layer, which is the portion where copper diffusion from the substrate is to be suppressed, is formed. In the region where the laser beam is not irradiated, there is no possibility of changing the material properties of the substrate, and the desired properties such as workability as a copper terminal material can be obtained. Can be maintained.

In the method for producing a copper terminal material of the present invention, the laser light may be laser light obtained from a solid laser, fiber laser, semiconductor laser, or gas laser and having a wavelength in the range of 200 nm to 1.1 μm.
By irradiating laser light having a wavelength in the above-mentioned range with these lasers from above the noble metal layer, the metal coating layer can be effectively enlarged.

  According to the present invention, the copper diffusion path can be reduced by the particle size adjusting portion of the diffusion prevention layer, and the copper diffusion of the base material itself can be suppressed by the altered layer of the base material. It is possible to provide a copper terminal material that can be increased and can maintain high reliability when a noble metal layer is provided thereon.

It is sectional drawing which shows typically the copper terminal material of embodiment of this invention. It is a flowchart which shows the 1st manufacturing method of the copper terminal material of embodiment. It is sectional drawing which shows typically the state which has irradiated the laser beam to the metal coating layer in the middle of manufacture of the 1st manufacturing method. It is a flowchart which shows the 2nd manufacturing method of the copper terminal material of embodiment. It is sectional drawing which shows typically the state which formed the noble metal layer in the metal coating layer in the middle of manufacture of the 2nd manufacturing method. It is sectional drawing which shows typically the state which irradiates the laser beam after forming a noble metal layer.

The copper terminal material of embodiment of this invention is demonstrated.
<Composition of copper terminal material>
In the copper terminal material 1 of the embodiment, as schematically shown in cross section in FIG. 1, a noble metal layer 4 is laminated on a base material 2 made of copper or a copper alloy via a diffusion prevention layer 3. .
If the base material 2 consists of copper or a copper alloy, the composition in particular will not be limited. In this case, immediately below the portion where the noble metal layer 4 is formed, an altered layer 2a in which the copper of the base material 2 and the metal in the diffusion preventing layer 3 are in a solid solution state is formed. The altered layer 2a here is a region formed on the side of the base material 2 from the boundary surface between the base material 2 and the diffusion prevention layer 3, and is a metal that is a main component in the diffusion prevention layer 3 (described later) The content ratio of nickel or cobalt is 1.0% by mass or more. In addition, the measuring method of content of the metal in a diffusion prevention layer is the area | region formed in the base material 2 side from the interface of the base material 2 and the diffusion prevention layer 3 from the cross section of the copper terminal material 1, EPMA ( This can be confirmed by quantitative analysis using an Electron Probe Micro Analysis).

  The diffusion prevention layer 3 has a thickness of 0.1 μm or more and 10.0 μm or less, and is constituted by one or more metal layers made of nickel, nickel alloy, cobalt, or cobalt alloy. Since it is one or more kinds of metal layers, diffusion preventing layer 3 made of nickel or nickel alloy, diffusion preventing layer 3 made of cobalt or cobalt alloy, or metal layer made of nickel or nickel alloy and metal made of cobalt or cobalt alloy It is good also as the diffusion prevention layer 3 which laminated | stacked combining these 3 or more types of the diffusion prevention layer 3 of 2 layer structure with a layer. In any case, the thickness of the diffusion preventing layer 3 as a whole is 0.1 μm or more and 10.0 μm or less. The diffusion preventing layer 3 has a function of preventing the diffusion of copper from the base material 2. When the thickness is less than 0.1 μm, the effect of preventing the diffusion of copper is poor, and the thickness exceeds 10.0 μm. And cracks are likely to occur during pressing. The thickness of the diffusion preventing layer 3 is more preferably 0.1 μm or more and 3.0 μm or less.

  The diffusion preventing layer 3 has a grain size adjustment in which the average crystal grain size is 0.3 μm or more in the portion where the noble metal layer 4 is laminated (the portion in contact with the altered layer 2a of the base material 2). Part 3a is formed. Since the average crystal grain size of the portion in contact with the noble metal layer 4 is 0.3 μm or more, the diffusion path can be reduced and the diffusion of copper from the substrate 2 to the noble metal layer 4 can be effectively prevented. The average crystal grain size of the diffusion preventing layer 3 in the region other than the grain size adjusting unit 3a is less than 0.3 μm.

  The noble metal layer 4 is composed of one or more of gold, gold alloy, silver, silver alloy, palladium, palladium alloy, platinum, platinum alloy, rhodium, and rhodium alloy, and the thickness thereof is 0.1 μm or more and 5.0 μm or less. It is said. This noble metal layer 4 has the effect of improving the heat resistance of the terminal material and reducing the contact resistance. If the thickness is less than 0.1 μm, characteristics as a noble metal such as improved heat resistance and reduced contact resistance cannot be obtained. When the thickness exceeds 5.0 μm, there is a possibility that cracking may occur during the pressing process on the terminal 10. The thickness of the noble metal layer 4 is more preferably 0.1 μm or more and 1.0 μm or less.

  Next, the manufacturing method of this copper terminal material 1 is demonstrated. As shown in FIGS. 2 and 3, the manufacturing method includes a first manufacturing method in which the noble metal layer 4 is formed after the diffusion prevention layer 3 is formed on the substrate 2, and FIGS. 4 and 5. As shown, there is a second manufacturing method in which the noble metal layer is formed after the metal coating layer 3 ′ is formed on the substrate 2, and then the diffusion barrier layer 3 is used as the metal coating layer 3 ′.

<First manufacturing method>
First, the first manufacturing method will be described with reference to the flowchart of FIG.
A plate material made of copper or a copper alloy is prepared as the base material 2, and the copper terminal material 1 is manufactured in the order shown in FIG. 2.
First, pretreatment is performed to clean the surface of the plate material by degreasing, pickling, or the like (pretreatment step).
Next, a metal coating layer 3 ′ for the diffusion preventing layer 3 is formed (metal coating layer forming step). The formation of the metal coating layer 3 ′ is preferably performed by a plating process.
When the metal coating layer 3 'is made of nickel or a nickel alloy, the plating bath is not particularly limited as long as a dense nickel-based film can be obtained, and a known watt bath, sulfamic acid bath, citric acid bath, etc. Can be formed by electroplating. As nickel alloy plating, nickel tungsten (Ni-W) alloy, nickel phosphorus (Ni-P) alloy, nickel cobalt (Ni-Co) alloy, nickel chromium (Ni-Cr) alloy, nickel iron (Ni-Fe) alloy, A nickel zinc (Ni—Zn) alloy, a nickel boron (Ni—B) alloy, or the like can be used.

When the metal coating layer 3 ′ is made of cobalt or a cobalt alloy, a general cobalt plating bath may be used as the plating bath. For example, a sulfamic acid bath, a cobalt sulfate bath, or the like can be used.
Considering the press bendability to the terminal and the barrier property against copper, pure nickel plating and pure cobalt plating obtained from a sulfamic acid bath are desirable.

After forming the metal coating layer 3 ′ on the substrate 2 in this way, as shown in FIG. 3, the surface of the portion of the metal coating layer 3 ′ where the noble metal layer 4 is formed is irradiated with the laser beam L. Then, the metal coating layer 3 'is locally heated. In addition, when the size of the part where the noble metal layer 4 is formed is smaller than the focal size of the laser beam L, the laser beam L is irradiated without scanning. On the other hand, when the size of the portion where the noble metal layer 4 is formed is larger than the focal size of the laser beam L, a scanning mirror such as a galvano mirror is used, and the laser is applied to the entire portion where the noble metal layer 4 is formed. The light L is scanned and irradiated (laser light irradiation step).
As the laser light, a solid laser, a fiber laser, a semiconductor laser (LD), or a gas laser can be used. The wavelength of the laser light is in the range of 400 nm to 11 μm, and the irradiation energy per unit area on the surface of the metal coating layer 3 ′ is 1.0 × 10 ² J / cm ² or more and 1.0 × 10 ⁶ J / cm ^2. Irradiate so that:

Since laser light has the feature of being able to locally collect high energy density light with a uniform wavelength, by using laser light, a complicated process is not required. In a short time, the crystal grains on the very surface can be locally enlarged. By this laser light irradiation, a particle size adjusting portion 3a having an average crystal grain size of 0.3 μm or more is formed in the portion irradiated with the laser light. In addition, since the heat generated by the laser light irradiation is also locally transmitted to the base material 2, the metal in the diffusion prevention layer 3 is dissolved in the copper of the base material 2 in contact with the particle size adjusting portion 3a. Thus, the deteriorated layer 2a is generated. For this reason, in this deteriorated layer 2a, the copper concentration is reduced, and the diffusion to the diffusion preventing layer 3 (particle size adjusting portion 3a) is suppressed accordingly.
In this way, by performing the laser beam irradiation process on the metal coating layer 3 ′, the diffusion prevention layer 3 in which the portion irradiated with the laser beam L becomes the particle size adjusting unit 3 a is formed, and the particle size thereof The deteriorated layer 2a is formed on the portion of the base material 2 that is in contact with the adjusting portion 3a.

Next, a mask M having an opening Ma as shown by a two-dot chain line in FIG. 3 is laminated on the portion of the diffusion prevention layer 3 where the noble metal layer 4 is formed, and immersed in a plating bath to open the mask M. The noble metal layer 4 is formed on the surface exposed to the portion Ma (noble metal layer forming step).
When the noble metal is made of gold (Au) or a gold alloy, the plating bath can be either a cyan bath mainly composed of potassium gold cyanide or a non-cyan bath using citric acid or the like. Temperature of the metallic bath 15 ℃ above 50 ° C. or less, the current density is set to 0.1 A / dm ² or more 10A / dm ² or less.
When the noble metal is made of silver (Ag) or a silver alloy, any of alkaline cyan bath, neutral cyan bath and non-cyan bath can be used as the plating bath. Temperature of the silver plating bath is 15 ℃ or 50 ° C. or less, the current density is set to 0.1 A / dm ² or more 10A / dm ² or less.
When the noble metal is made of palladium (Pd) or a palladium alloy, the plating bath is a neutral or alkaline aqueous ammonium solution, and typical palladium compounds include palladium chloride, dinitrodiammine palladium, dichloroaminopalladium and the like. Any bath can be used. The temperature of the palladium plating bath is 35 ° C. or more and 60 ° C. or less, and the current density is 0.5 A / dm ² or more and 5 A / dm ² or less.
When the noble metal is made of platinum (Pt) or a platinum alloy, the plating bath is roughly divided into a bath using a divalent (II) platinum compound and a bath using a tetravalent (IV) platinum compound. There are baths that use dinitrodiaminoplatinum and potassium platinum hydroxide as divalent platinum compounds as acidic to neutral, or baths that use hexachloride platinic acid as alkaline and tetravalent platinum compounds. The bath can also be used. The temperature of the platinum plating bath is 65 ° C. or more and 90 ° C. or less, and the current density is 0.1 A / dm ² or more and 5.0 A / dm ² or less.
When the noble metal is made of rhodium (Rh) or a rhodium alloy, any of a sulfuric acid bath, a phosphoric acid bath, a borofluoric acid bath, and a sulfamic acid bath can be used as the plating bath. The temperature of the rhodium plating bath is 35 ° C. or more and 60 ° C. or less, and the current density is 0.3 A / dm ² or more and 30 A / dm ² or less.
After forming the noble metal layer 4, when the mask M is removed, the copper terminal material 1 is completed.

In the copper terminal material 1 manufactured in this way, the diffusion preventing layer 3 is formed on the base material 2, and the noble metal layer 4 is partially formed thereon. And it is processed into the shape of a terminal by press processing or the like.
In this terminal, in the portion where the noble metal layer 4 is laminated, an altered layer 2a in which the metal of the diffusion preventing layer 3 is formed as a solid solution is formed on the substrate 2, and the average crystal grain size is 0.3 μm in the diffusion preventing layer 3. Since the particle size adjusting portion 3a is formed as described above, diffusion of copper from the base material 2 to the noble metal layer 4 can be effectively prevented, and excellent heat resistance can be maintained. For example, even when exposed to a temperature of 200 ° C. for a long time (up to 1000 hours), it is possible to suppress the copper of the base material 2 from diffusing the diffusion preventing layer 3 and being deposited on the noble metal layer 4.
In addition, since the laser beam is irradiated only from the surface of the necessary portion of the metal coating layer 3 ′, the material characteristics of the base material 2 made of copper or copper alloy are changed in the region where the laser beam is not irradiated. However, the material properties such as workability to the terminal can be maintained well.

<Second production method>
Next, the second manufacturing method will be described with reference to the flowchart of FIG. Also in the second manufacturing method, the pretreatment process for the base material and the metal coating layer forming process are the same as in the first manufacturing method.
After forming the metal coating layer 3 ′ on the base material 2 by these steps, as shown in FIG. 5, an opening Ma is formed on the metal coating layer 3 ′ in the portion where the noble metal layer 4 is formed. The mask M is stacked, the noble metal layer 4 is formed on the surface exposed from the opening Ma by plating, and then the mask M is removed (noble metal layer forming step). The precious metal plating conditions are the same as in the first manufacturing method described above.
Next, as shown in FIG. 6, laser light is irradiated from above the noble metal layer 4 to locally heat the metal coating layer 3 ′. In addition, when the size of the portion where the noble metal layer 4 is formed is smaller than the focal size of the laser beam, the laser beam is irradiated without scanning. On the other hand, when the size of the portion where the noble metal layer 4 is formed is larger than the focal size of the laser beam, a scanning mirror such as a galvano mirror is used, and the laser beam is applied to the entire portion where the noble metal layer 4 is formed. Are scanned and irradiated (laser beam irradiation step).

As the laser light, a solid laser, a fiber laser, a semiconductor laser (LD), or a gas laser can be used. The wavelength of the laser light is in the range of 200 nm to 1.1 μm, and the irradiation energy per unit area on the surface of the metal coating layer 3 ′ is 1.0 × 10 ² J / cm ^{2 to} 1.0 × 10 ⁶ J /. Irradiation is carried out so as to be not more than cm ²
By this laser light irradiation, the metal coating layer 3 ′ is heated by the laser light that has passed through the noble metal layer 4, and the crystal grains immediately below the noble metal layer 4 are enlarged to an average crystal grain size of 0.3 μm or more. The diffusion preventing layer 3 having the diameter adjusting portion 3a is formed, and further, the altered layer 2a is formed on the substrate 2 in contact with the particle size adjusting portion 3a.

In this case, since the noble metal layer 4 has a high reflectivity with respect to the laser beam and a low absorptance, the noble metal layer 4 preferably has a short wavelength. The metal coating layer 3 'is instantaneously heated by the thermal energy of the laser beam, and crystal grains are enlarged.
The copper terminal material 1 manufactured in this manner has an altered layer 2a in which a diffusion preventing layer 3 is formed on a substrate 2 and a metal in the diffusion preventing layer 3 is dissolved in a part of the substrate 2. A grain size adjusting portion 3a having an average crystal grain size of 0.3 μm or more in the diffusion preventing layer 3 is formed on the altered layer 2a, and a noble metal layer 4 is formed thereon. . And like the 1st manufacturing method, it is processed into the shape of a terminal by press processing etc.
In this second manufacturing method, since the laser beam is irradiated after the noble metal layer 4 is formed, the particle size adjusting portion 3a and the base material 2 immediately below it are surely applied to the diffusion preventing layer 3 immediately below the noble metal layer 4. The altered layer 2a can be formed.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the embodiment, the metal coating layer 3 ′ and the noble metal layer 4 are formed by plating, but other thin film forming methods such as sputtering may be used.

As the base material, a material having a thickness of 0.25 mm with a CDA (Copper Development Association) alloy number shown in Table 1 was used. As pretreatment, electrolytic degreasing (using 60 g / l NaOH aqueous solution, liquid temperature 60 ° C., current density 2.5 ASD (A / dm ² ), degreasing time 60 seconds) and pickling (10% sulfuric acid aqueous solution, liquid temperature 25 C., immersion time 30 seconds).

The metal coating layer is formed by plating. When the metal coating layer is nickel (Ni), an aqueous solution of nickel sulfamate tetrahydrate, 500 g / liter, an aqueous solution of nickel chloride, 30 g / liter, boron Using an acid aqueous solution, 30 g / liter, a metal coating layer made of nickel (Ni) having a thickness and a crystal grain size shown in Table 1 was obtained at a liquid temperature of 50 ° C. and a current density of 15 ASD. When the metal coating layer is cobalt (Co), an aqueous solution of cobalt sulfamate tetrahydrate, 500 g / liter, an aqueous solution of cobalt chloride, 30 g / liter, an aqueous solution of boric acid, 30 g / liter are used. At a liquid temperature of 50 ° C. and a current density of 6 ASD, a metal coating layer made of cobalt (Co) having the thickness and crystal grain size shown in Table 1 was obtained.
The laser beam was irradiated to the predetermined area where the noble metal layer was formed with the laser type and conditions shown in Table 1. When the area where the noble metal layer is formed is larger than the focal spot size, the entire area was irradiated by irradiating the laser light having the conditions shown in Table 1 a plurality of times.
In Table 1, “.E +” and subsequent numbers in the irradiation energy indicate exponential notation, and for example “4.0 × E ³ ” indicates “4.0 × 10 ³ ”.

  The outermost noble metal layer is formed by plating. When the noble metal layer is gold (Au), an aqueous solution of potassium gold cyanide, 14.6 g / liter, an aqueous solution of citric acid, 150 g / liter, and potassium citrate Using an aqueous solution, 180 g / liter, a noble metal layer made of gold (Au) having a thickness and a crystal grain size shown in Table 1 was obtained at a liquid temperature of 40 ° C. and a current density of 5 ASD. When the noble metal layer is palladium (Pd), an aqueous solution of diamminedichloropalladium (II), 45 g / liter, an aqueous ammonium solution, 90 ml / liter, an aqueous solution of ammonium sulfate, 50 g / liter, and a liquid temperature of 30 A noble metal layer made of palladium (Pd) having a thickness and a crystal grain size shown in Table 1 was obtained at a temperature of 6 ° C. and a current density of 6 ASD. Further, when the noble metal layer is platinum (Pt), an aqueous solution of dinitrodiammineplatinum (II), 10 g / liter, an aqueous solution of ammonium nitrate, 100 g / liter, an aqueous ammonium solution, 50 ml / liter, and a liquid temperature of 80 A noble metal layer made of platinum (Pt) having a thickness and a crystal grain size shown in Table 1 was obtained at a current density of 3 ASD. When the noble metal layer is silver (Ag), an aqueous solution of silver cyanide, 50 g / liter, an aqueous solution of potassium cyanide, 100 g / liter, an aqueous solution of potassium carbonate, 30 g / liter, a liquid temperature of 30 ° C., A noble metal layer made of silver (Ag) having a thickness and a crystal grain size shown in Table 1 was obtained at a current density of 1 ASD. Further, when the noble metal layer is rhodium (Rh), the thickness shown in Table 1 is obtained using an aqueous solution of rhodium, 2.0 g / liter, sulfuric acid, and 35 milliliters at a liquid temperature of 40 ° C. and a current density of 1.5 ASD. Thus, a noble metal layer made of rhodium (Rh) having a crystal grain size was obtained.

About the obtained sample, the thickness of the altered layer is measured by quantitatively analyzing the content of the main metal component in the diffusion prevention layer of the portion irradiated with the laser beam (modified layer) in the base material, After measuring the average crystal grain size of the part (grain size adjusting part) irradiated with the laser beam in the diffusion preventing layer, the contact resistance and bending workability were evaluated.
(Measurement method of film thickness and average crystal grain size)
The film thickness and average crystal grain size were measured by cross-sectional observation described below. For the film thickness and average crystal grain size of the metal coating layer to be measured, the laser-irradiated portion of the diffusion prevention layer, and the noble metal layer, after cutting the rolled parallel section with FIB, the section is exposed, For each target layer, the magnification is set to 8000 to 15000 times, and the cross section is observed by SIM. Then, the thickness of each layer is measured in the obtained image. On the other hand, a length of 5 μm is drawn from the central portion in the thickness direction in the plane direction of the base material, and the number of crystal grain boundaries intersecting each line is confirmed with that line, and 5 μm is divided by the number. Is defined as the crystal grain size. This was measured three times at an arbitrary location per field of view, and was performed for a total of 3 fields of view and 9 locations. The average value of the measured values obtained was taken as the average crystal grain size of each layer.

(Method for measuring thickness of altered layer of base material)
The thickness of the altered layer of the base material was measured by cross-sectional observation described below.
Based on the boundary surface between the base material to be measured and the diffusion prevention layer, the region on the base material side is quantitatively analyzed by EPMA (Electron Probe Micro Analysis), and the content of main metals in the diffusion prevention layer is 1. The width of the region of 0% by mass or more was measured, and the thickness of the deteriorated layer was determined.

(Contact resistance measurement and evaluation method)
The contact resistance of the noble metal layer on the outermost surface was measured in accordance with JCBA-T323 using a four-terminal contact resistance tester with a sliding type (1 mm) at a load of 0.98 N. First, after measuring the initial contact resistance immediately after the formation of the noble metal layer, the contact resistance was measured again after being kept in an air atmosphere at 200 ° C. for 1000 hours as a heat treatment. From the initial measurement, the change rate of the measured value after holding at 200 ° C. for 1000 hours is less than 10% as “◎”, 10% or more and less than 20% as “◯”, 20% or more, 25 Less than% was designated as “△”, and 25% or more was designated as “x”.

(Bending workability evaluation method)
Regarding bending workability, a plurality of test pieces having a width of 10 mm and a length of 30 mm were collected so that the bending axis was perpendicular to the rolling direction, and four test methods of JCBA (Japan Copper and Brass Association Technical Standard) T307 were used. In accordance with the above, a W-bending test was performed with a load of 9800 N using a W-shaped jig having a bending angle of 90 ° and a bending radius of 0.5 mm. Then, it observed with the stereomicroscope. In the evaluation of bending workability, the level at which clear cracks are not recognized in the bent part after the test is indicated as “◎”, and fine cracks are partially generated on the plated surface, but exposure of the copper base material is recognized. The level that is not allowed is “O”, the copper base material is not exposed, but the level at which a crack larger than the level evaluated as “O” is generated is “△”, and the copper base material is exposed by the generated crack. The level is “×”.
These results are shown in Table 1.

  As can be seen from the results of Table 1, the altered layer of the substrate is 1 μm or more and 5 μm or less, contains 1.0% by mass or more of the metal in the diffusion prevention layer, and has a thickness of 0.1 μm formed thereon. A copper terminal material having a small change in contact resistance before and after heating and excellent bending workability when the average crystal grain size of the grain size adjusting portion in the diffusion preventing layer of 10.0 μm or less is 0.3 μm or more. It has become. Sample No. 52 was too long to be irradiated with the laser beam, and the base material was partially melted by the heat from the laser, so the characteristics could not be evaluated and measurement was impossible.

DESCRIPTION OF SYMBOLS 1 Copper terminal material 2 Base material 2a Alteration layer 3 Metal layer 3 'Metal coating layer 4 Noble metal layer M Mask Ma Opening part

Claims (7)

  A diffusion prevention layer having a thickness of 0.1 μm or more and 10.0 μm or less is formed on a substrate made of copper or a copper alloy, and at least a part of the diffusion prevention layer has an average crystal grain size of 0.3 μm or more. The particle size adjusting part is formed, and the diffusion is performed on the portion of the base material in contact with the particle size adjusting part within a thickness range from 1 μm to 50 μm from the boundary surface with the particle size adjusting part. A copper terminal material, wherein a deteriorated layer having a metal content of 1.0% by mass or more in a prevention layer is formed.   2. The copper terminal material according to claim 1, wherein the diffusion prevention layer is constituted by one or more metal layers made of any one of nickel, nickel alloy, cobalt, and cobalt alloy.   A thickness of at least one layer of gold, gold alloy, silver, silver alloy, palladium, palladium alloy, platinum, platinum alloy, rhodium, or rhodium alloy is formed on the particle size adjusting portion in the diffusion preventing layer. The copper terminal material according to claim 1, wherein a noble metal layer having a thickness of 1 μm to 5.0 μm is formed.   4. The method for producing a copper terminal material according to claim 1, wherein a metal coating layer is formed on a surface of the base material, and then a laser is applied to at least a part of the surface of the metal coating layer. By irradiating light, the metal coating layer is used as the diffusion preventing layer in which the portion irradiated with the laser light is the particle size adjusting portion, and the base material in the portion in contact with the particle size adjusting portion The above-mentioned deteriorated layer is formed on the copper terminal material.   5. The method for producing a copper terminal material according to claim 4, wherein the laser beam is a laser beam obtained from a solid laser, a fiber laser, a semiconductor laser, or a gas laser and having a wavelength in the range of 400 nm to 11 μm.   4. The method for producing a copper terminal material according to claim 3, wherein after the metal coating layer is formed on the surface of the substrate, the noble metal layer is formed on at least a part of the surface of the metal coating layer. By irradiating the surface of the layer with laser light, the metal coating layer is used as the diffusion prevention layer in which the portion irradiated with the laser light is the particle size adjusting unit, and is in contact with the particle size adjusting unit. A method for producing a copper terminal material, comprising forming the altered layer on a portion of the base material.   The method for producing a copper terminal material according to claim 6, wherein the laser beam is a laser beam having a wavelength in a range of 200 nm to 1.1 µm, which is obtained from a solid laser, a fiber laser, a semiconductor laser, or a gas laser. .

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