JP2016169439A - Copper terminal material with tin plating, manufacturing method therefor and wire terminal part structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal material without generating electric corrosion by using copper or a copper alloy substrate as a terminal crimped to a terminal of a wire consisting of an aluminum wire material.SOLUTION: A ground layer consisting of nickel or a nickel alloy, a nickel tin zinc alloy layer and a tin layer are laminated on a substrate consisting of copper or a copper alloy in this order. The nickel tin zinc alloy layer has thickness of 0.13 μm to 1 μm, and contains nickel of 15 at% to 60 at%, zinc of 10 at% to 60 at% and the balance tin.SELECTED DRAWING: Figure 1

Description

  The present invention is used as a terminal to be crimped to an end of an electric wire made of an aluminum wire, and has a tin-plated copper terminal material in which the surface of a copper or copper alloy base material is plated with tin or a tin alloy, its manufacturing method, and The present invention relates to a wire terminal part structure.

Conventionally, by crimping a terminal made of copper or a copper alloy to the terminal part of an electric wire made of copper or a copper alloy, and connecting the terminal to a terminal of another device, Connecting to equipment is done. Further, in order to reduce the weight of the electric wire, the electric wire may be made of aluminum or aluminum alloy instead of copper or copper alloy.
For example, Patent Document 1 discloses an aluminum wire for an automobile wire harness made of an aluminum alloy.

  By the way, when the electric wire (conducting wire) is made of aluminum or an aluminum alloy and the terminal is made of copper or a copper alloy, when water enters the crimping portion (engagement portion between the terminal and the electric wire), it depends on the potential difference between different metals. Electrical corrosion may occur. And with the corrosion of the electric wire, there is a risk that an increase in the electric resistance value at the crimping portion and a decrease in the adhering force (bonding force between the terminal and the electric wire) may occur.

Examples of methods for preventing this corrosion include those described in Patent Document 2 and Patent Document 3.
Patent Document 2 includes a metal part made of a first metal material and a second metal material having a standard electrode potential value smaller than that of the first metal material, and at least a surface of the metal part. It is composed of an intermediate layer that is thinly provided by plating and a third metal material having a standard electrode potential smaller than that of the second metal material, and is thinly provided by plating on at least a part of the surface of the intermediate layer. A terminal having a surface layer is disclosed. The first metal material is copper or an alloy thereof, the second metal material is lead or an alloy thereof, tin or an alloy thereof, nickel or an alloy thereof, zinc or an alloy thereof, and the third metal material is Aluminum or its alloys are described.

  In Patent Document 3, in the terminal region of the covered electric wire, the caulking portion formed at one end of the terminal metal fitting is caulked along the outer periphery of the covering portion of the covered electric wire, and at least the end exposed region of the caulking portion and the vicinity thereof A wire harness terminal structure is disclosed in which the entire outer periphery of the wire harness is completely covered with a mold resin.

JP 2004-134212 A JP 2013-33656 A JP 2011-222243 A

  However, although the structure described in Patent Document 3 can prevent corrosion, there is a problem that the manufacturing cost increases due to the addition of the resin molding process, and further, the miniaturization of the wire harness is hindered by the increase of the terminal cross-sectional area due to the resin. In order to carry out the aluminum-based plating that is the third metal material described in 2, an ionic liquid or the like is used, which causes a problem that it is very expensive.

  By the way, in many cases, a tin-plated terminal material obtained by subjecting a copper or copper alloy base material to tin plating and reflow treatment is used. When this tin-plated terminal material is crimped to an aluminum electric wire, it should be difficult to cause electrolytic corrosion because tin and aluminum have close corrosion potentials, but electrolytic corrosion occurs when salt water or the like adheres to the crimping portion.

  This invention is made in view of the above-mentioned subject, Comprising: As a terminal crimped | bonded to the terminal of the electric wire which consists of aluminum wires, the terminal material which does not produce electrolytic corrosion using a copper or copper alloy base material is provided. With the goal.

As a result of earnest research on the electrolytic corrosion of the tin-plated terminal material, the inventors quickly disappeared a layer made of tin or a tin alloy on the surface (hereinafter referred to as a tin layer) due to the corrosive action of salt water, and the lower layer copper It was found that electrolytic corrosion occurs because the tin alloy layer is exposed. Since the corrosion potential of the copper-tin alloy layer is close to that of copper, a high potential difference is generated and aluminum is preferentially corroded.
Therefore, instead of the copper-tin alloy layer, an alloy layer having a corrosion potential close to that of aluminum is formed, so that the occurrence of electrolytic corrosion can be suppressed even if the tin layer disappears.

  That is, in the copper terminal material with tin plating of the present invention, the base layer made of nickel or nickel alloy, the nickel tin zinc alloy layer, and the tin layer made of tin or tin alloy are arranged in this order on the base material made of copper or copper alloy. The nickel tin zinc alloy layer is laminated and has a thickness of 0.13 μm or more and 1 μm or less, nickel is contained at 15 at% or more and 60 at% or less, zinc is contained at 10 at% or more and 60 at% or less, and the remainder is made of tin.

  In this tin-plated copper terminal material, a nickel tin-zinc alloy layer having a relatively close corrosion potential to aluminum is formed between the base layer on the substrate and the tin layer on the surface, so that the tin layer disappears. Even if the nickel tin zinc alloy layer is exposed, the occurrence of electrolytic corrosion can be suppressed.

  If the thickness of the nickel tin zinc alloy layer is less than 0.13 μm, the nickel in the underlayer is easily exposed after the disappearance of the tin layer, and electrolytic corrosion occurs between the nickel layer and aluminum, and if the thickness exceeds 1 μm, the press Since workability deteriorates, it is not preferable. If the nickel content of the nickel-tin-zinc alloy layer is less than 15 at%, the corrosion resistance of the alloy layer deteriorates, and when exposed to a corrosive environment such as salt water, the alloy layer rapidly corrodes and the underlying nickel is exposed. Electrocorrosion is likely to occur with aluminum, and if it exceeds 60 at%, the corrosion potential of the alloy layer becomes noble and promotes electrolytic corrosion with aluminum. Further, when the zinc content is less than 10 at%, the corrosion potential becomes noble and promotes electrolytic corrosion with aluminum, and when it exceeds 60 at%, the corrosion resistance deteriorates.

  In the copper terminal material with tin plating of the present invention, the nickel content of the nickel tin zinc alloy layer is high on the substrate side, low on the surface side, further low in zinc content on the surface side, and high on the substrate side.

  Thus, by taking a structure in which the nickel content of the nickel tin zinc alloy layer is high on the substrate side and the surface side is low, even when the tin layer is corroded and the nickel tin zinc alloy layer is exposed, aluminum and The corrosion resistance of the nickel tin zinc alloy layer can be enhanced while the formation of the corrosion battery is prevented, and the exposure of the copper or copper alloy base material or the nickel or nickel alloy plating layer can be prevented.

  Specifically, in the tin-plated copper terminal material of the present invention, the nickel tin zinc alloy layer has a thickness of 0.05 μm or more, nickel of 25 at% to 60 at%, and zinc of 30 at% to 60 at%. A second alloy layer having a thickness of 0.08 μm or more, nickel of 15 at% to 40 at%, zinc of 10 at% to 40 at%, and a balance of tin. They are laminated in order from the substrate side.

  Furthermore, by making the nickel tin zinc alloy layer have a two-layer structure in which the nickel content and the zinc content are stepwise different, the corrosion resistance can be improved while further suppressing the formation of the corrosion battery. That is, the second alloy layer on the surface side has nickel content of 15 at% or more and 40 at%, but the zinc content is lower than the first alloy layer, so the corrosion resistance is superior to the first alloy layer, and the tin layer disappears. In this case, it is possible to prevent the alloy layer from being rapidly lost by being exposed to a corrosive environment. When the corrosion further progresses and the second alloy layer is damaged, the underlying copper alloy base material or nickel or nickel alloy plating layer may be exposed due to the progress of local corrosion. At this time, the second alloy layer containing 30 at% or more and 60 at% or less of zinc and having a base corrosion potential serves as a sacrificial anode, and the progress of electrolytic corrosion with aluminum can be suppressed.

  If the thickness of the first alloy layer is less than 0.05 μm, when the second alloy layer is damaged and the first alloy layer is exposed, the first alloy layer is rapidly corroded to prevent electrolytic corrosion. The effect to do becomes poor. When the nickel content is less than 25 at%, the corrosion resistance of the alloy layer deteriorates, and when the first alloy layer is exposed, the corrosion disappears quickly, so the effect of preventing electrolytic corrosion is poor. Since it becomes noble, it becomes a sacrificial anode and cannot prevent the progress of electrolytic corrosion with aluminum. If the zinc content is less than 30 at%, the corrosion potential becomes noble and becomes a sacrificial anode, and the effect of preventing the progress of electrolytic corrosion with aluminum is poor. If it exceeds 60 at%, the corrosion resistance of the alloy layer deteriorates, and the first alloy When the layer is exposed, the corrosion disappears quickly, so that the effect of preventing electrolytic corrosion becomes poor.

  If the thickness of the second alloy layer is less than 0.08 μm, when the tin layer disappears, the second alloy layer is exposed to the corrosive environment and disappears quickly, so that the effect of suppressing electrolytic corrosion is poor. When the nickel content is less than 15 at%, the corrosion resistance deteriorates, and when the tin layer disappears, the second alloy layer is exposed to the corrosive environment and quickly disappears, so the effect of preventing electrolytic corrosion becomes poor, and 40 at% If it exceeds 1, the corrosion potential of the alloy layer becomes noble and forms a corrosion cell with aluminum, so the effect of preventing electrolytic corrosion becomes poor. If the zinc content of the first alloy layer is less than 10 at%, the corrosion potential of the alloy layer becomes noble and the effect of preventing electrolytic corrosion is poor because it forms a corrosion cell with aluminum, and if it exceeds 40 at%, the corrosion resistance deteriorates. When the tin layer disappears, the alloy layer is exposed to the corrosive environment and quickly disappears, so that the effect of preventing electrolytic corrosion is poor.

In the copper terminal material with tin plating of the present invention, a metal zinc layer having a zinc concentration of 20 at% to 40 at% and a thickness of 3 nm to 30 nm in terms of SiO ₂ may be formed on the tin layer.

Since the corrosion potential of metallic zinc is close to that of aluminum, if this very thin metallic zinc layer is formed on the surface, it is possible to more effectively suppress the occurrence of electrolytic corrosion when it comes into contact with an aluminum electric wire. Since the thickness of the metal zinc layer is very thin, the electrical connection reliability is not impaired. In this case, if the zinc concentration of the metal zinc layer is less than 20 at%, there is no effect of lowering the corrosion potential, and if it exceeds 40 at%, the contact resistance deteriorates. If the thickness of the metal zinc layer in terms of SiO ₂ is less than 3 nm, there is no effect of lowering the corrosion potential, and if it exceeds 30 nm, the contact resistance is deteriorated.

  The method for producing a tin-plated copper terminal material of the present invention includes a nickel plating step of forming a nickel or nickel alloy plating layer on a surface of a base material made of copper or a copper alloy with a thickness of 0.1 μm or more and 5 μm or less, A tin plating step of forming a tin plating layer on the nickel or nickel alloy plating layer with a thickness of 0.3 μm or more and 2.0 μm or less; and a zinc plating layer on the tin plating layer of 0.05 μm or more and 1.5 μm A galvanizing step formed with the following thickness, and after the galvanizing step, heated to a temperature of 230 ° C. or more and 600 ° C. or less, an underlayer made of nickel or a nickel alloy, a tin layer, and these underlayers A heat treatment step of forming a nickel tin zinc alloy layer between the tin layer.

When the thickness of the nickel or nickel alloy plating layer is less than 0.1 μm, the amount of nickel is insufficient, and a desired nickel tin zinc alloy layer cannot be formed. On the other hand, if the thickness of the nickel or nickel alloy plating layer exceeds 5 μm, the plating film is cracked by bending during pressing, which is not desirable. The preferred thickness of the nickel or nickel alloy plating layer is not less than 0.2 μm and not more than 0.6 μm.
When the thickness of the tin plating layer is less than 0.3 μm, the nickel tin zinc alloy layer is exposed on the surface, and the contact resistance of the terminal deteriorates. If the thickness exceeds 2 μm, cracks are likely to occur during press molding.
If the thickness of the galvanized layer is less than 0.05 μm, zinc is insufficient, so that a desired nickel tin zinc alloy layer cannot be obtained. When the thickness exceeds 1.5 μm, thick pure zinc remains in the outermost layer during the thermal diffusion treatment, and the contact resistance deteriorates.
In the heat treatment after plating, when the temperature is lower than 230 ° C., tin does not sufficiently melt, so that a desired nickel tin zinc alloy layer cannot be obtained. On the other hand, when the temperature exceeds 600 ° C., diffusion proceeds excessively, and a nickel tin zinc alloy layer is exposed on the surface in a large amount, so that contact resistance is deteriorated.

  In the production method of the present invention, when the temperature of the heat treatment step is 250 ° C. or more and 350 or less, the above-described very thin metal zinc layer is formed on the surface of the tin layer, and generation of electrolytic corrosion can be effectively suppressed. .

  And it was set as the electric wire terminal part structure where the terminal which consists of a copper terminal material with a tin plating of this invention was crimped | bonded to the terminal of the electric wire which consists of aluminum or an aluminum alloy.

  According to the present invention, since the nickel tin zinc alloy layer is provided between the base layer on the base material and the tin layer on the surface, even when the tin layer disappears, the electric corrosion with the aluminum wire is prevented and the electric corrosion is prevented. An increase in resistance value and a decrease in fixing force can be suppressed.

It is sectional drawing which shows typically the copper terminal material with a tin plating of this invention. It is a perspective view which shows the example of the terminal to which the terminal material of this invention is applied. It is a front view which shows the terminal part of the electric wire which crimped | bonded the terminal of FIG. Sample No. It is a two-dimensional composition map image by the energy dispersive X-ray analysis of 3 cross sections. FIG. 5 is a line analysis diagram of a range indicated by an arrow in FIG. 4. 4 is a concentration distribution diagram of each element in a depth direction by XPS analysis in a surface portion of a sample 10. FIG. 2 is a chemical state analysis diagram in the depth direction of a sample 10. FIG.

The copper terminal material with a tin plating of embodiment of this invention and its manufacturing method are demonstrated.
As schematically shown in FIG. 1, the tin-plated copper terminal material 1 of the present embodiment has a base layer 3 made of nickel or a nickel alloy on a base material 2 made of copper or a copper alloy, and a nickel tin zinc alloy layer. 4 and the tin layer 5 are laminated in this order, and the nickel tin zinc alloy layer 4 is further laminated in sequence with a first alloy layer 6 and a second alloy layer 7 having different contents of nickel, tin and zinc. It has a structure.
It is more preferable that the metal zinc layer 8 is formed very thin on the tin layer 5.

  If the base material 2 consists of copper or a copper alloy, the composition in particular will not be limited.

  As will be described later, the base layer 3 is formed by sequentially forming a nickel or nickel alloy plating layer, a tin plating layer, and a zinc plating layer on the substrate 2, and then the heat treatment is performed to leave the nickel or nickel alloy plating layer. It is a formed layer. The thickness of the underlayer 3 is preferably 0.1 μm or more and 0.5 μm or less.

  The nickel tin zinc alloy layer 4 was formed between the underlayer 3 and the surface tin layer 5 by forming the above-described nickel or nickel alloy plating layer, tin plating layer, and zinc plating layer and performing heat treatment. Alloy layer. As a whole, the thickness is 0.13 μm or more and 1 μm or less, nickel is contained in 15 at% or more and 60 at% or less, zinc is contained in 10 at% or more and 60 at% or less, and the balance is tin.

  If the thickness of the nickel tin zinc alloy layer 4 is less than 0.13 μm, it is easy to cause electrolytic corrosion between nickel and tin or aluminum of the underlayer 3. . When the nickel content of the nickel tin zinc alloy layer 4 is less than 15 at%, the corrosion resistance of the alloy layer is deteriorated, and when it exceeds 60 at%, the corrosion potential becomes noble and promotes electrolytic corrosion with aluminum. Further, when the zinc content is less than 10 at%, the corrosion potential becomes noble and promotes electrolytic corrosion with aluminum, and when it exceeds 60 at%, the corrosion resistance deteriorates.

  Further, the nickel tin zinc alloy layer 4 has a laminated structure composed of two layers as described above. That is, the first alloy layer 6 having a thickness of 0.05 μm or more, nickel of 25 at% or more and 60 at% or less, zinc of 30 at% or more and 60 at% or less and the balance of tin, and a thickness of 0.08 μm or more of nickel The second alloy layer 7 containing 15 at% or more and 40 at% or less, zinc at 10 at% or more and 40 at% or less, and the balance being tin is laminated in order from the substrate 2 side.

  The tin layer 5 is a layer made of tin in which the above-described tin plating layer is formed by heat treatment. The thickness of the tin layer 5 is preferably 0.2 μm or more and 1.5 μm or less. If the thickness is too thin, the solder wettability and the electrical connection reliability may be decreased. The increase in resistance tends to increase the attachment / detachment resistance during use with a connector or the like. The tin layer 5 is most preferably pure tin, but may be an alloy such as zinc, nickel, or copper.

The metal zinc layer 8 has a zinc concentration of 20 at% to 40 at% and a thickness of 3 nm to 30 nm in terms of SiO ₂ . If the zinc concentration of the metallic zinc layer 8 is less than 20 at%, there is no effect of lowering the corrosion potential, and if it exceeds 40 at%, the contact resistance deteriorates. The zinc concentration of the metal zinc layer 8 is more preferably 25 at% or more and 35 at% or less.
On the other hand, if the thickness of the metal zinc layer 8 in terms of SiO ₂ is less than 3 nm, there is no effect of lowering the corrosion potential, and if it exceeds 30 nm, the contact resistance deteriorates. The SiO ₂ equivalent thickness is more preferably 5 nm or more and 10 nm or less.
A thin oxide layer of zinc or tin is formed on the outermost surface.

Next, the manufacturing method of this copper terminal material 1 with a tin plating is demonstrated.
A plate material made of copper or a copper alloy is prepared as the substrate 2. After the surface of the plate material is cleaned by degreasing, pickling, etc., nickel or nickel alloy plating, tin plating, and zinc plating are applied in this order.

The nickel or nickel alloy plating is not particularly limited as long as a dense nickel-based film can be obtained, and can be formed by electroplating using a known watt bath, sulfamic acid bath, citric acid bath, or the like. 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.
Considering the press bendability to the terminal and the reactivity with zinc, a pure nickel plating layer obtained from a sulfamic acid bath is desirable. Such a nickel plating layer is preferably formed on the substrate with a thickness of 0.2 μm or more and 0.6 μm or less.

Tin plating for the tin plating layer can be performed by a known method. For example, an organic acid bath (for example, a phenolsulfonic acid bath, an alkanesulfonic acid bath or an alkanolsulfonic acid bath), a borofluoric acid bath, a halogen bath, Electroplating can be performed using an acidic bath such as a sulfuric acid bath or pyrophosphoric acid bath, or an alkaline bath such as a potassium bath or sodium bath. In order to prevent problems, it is desirable to suppress the carbon content in the tin plating layer to 0.1% by mass or less, and a matte bath or semi-gloss bath that does not contain a component that increases the carbon content such as formaldehyde and acrylic acid is preferable. Pure tin plating is most preferable because it does not hinder the thermal diffusion of zinc, but tin copper alloy plating, tin zinc alloy plating, or tin nickel alloy plating may be used.
The thickness of this tin plating layer is set to 0.3 μm or more and 2 μm or less. If the thickness is less than 0.3 μm, the nickel tin zinc alloy layer is exposed on the surface, and the contact resistance of the terminal deteriorates. If the thickness exceeds 2 μm, cracks are likely to occur during press molding.

The galvanized layer can be formed by a known method, and can be electroplated using, for example, a zincate bath, a sulfate bath, a zinc chloride bath, or a cyan bath. In order to smoothly perform the thermal diffusion of zinc, a sulfate bath that does not contain a carbon component in electrodeposited zinc and does not contain an additive is particularly preferable.
This galvanized layer is set to a thickness of 0.05 μm or more and 1.5 μm or less. If the thickness is less than 0.05 μm, zinc is insufficient and a desired nickel tin zinc alloy layer cannot be obtained. When the thickness exceeds 1.5 μm, pure zinc remains in the outermost layer during the thermal diffusion treatment, and the contact resistance is deteriorated.

In this manner, nickel or nickel alloy plating, tin plating, and zinc plating are applied on the base material in this order, and then heat treatment is performed.
This heat treatment is performed for 5 seconds to 30 seconds in a reducing atmosphere under conditions where the surface temperature of the material is 230 ° C. or higher and 600 ° C. or lower.

  As a result of this heat treatment, the tin plating layer melts, and the zinc in the surface galvanization layer diffuses into the lower layer and reacts with a part of nickel or a nickel alloy. These intermetallic compounds of nickel tin zinc are produced. Then, a part of the nickel or nickel alloy layer remains on the base material 2 and a part of the tin remains on the surface, so that the base layer 3 made of nickel or a nickel alloy in order from the base material 2 side, nickel A tin-zinc alloy layer 4 and a tin layer 5 are formed.

Under this heat treatment condition, if the temperature is lower than 230 ° C., tin is not sufficiently melted, so that the desired nickel tin zinc alloy layer 4 cannot be obtained. On the other hand, if the temperature exceeds 600 ° C., the diffusion proceeds excessively, the nickel tin zinc alloy layer 4 is exposed on the surface in a large amount, the contact resistance is deteriorated, the thickness is excessively increased, and the bending workability is deteriorated. Therefore, it is not desirable.
If the heating time is less than 5 seconds, the formation of the alloy layer is insufficient and the desired thickness cannot be obtained. If it exceeds 30 seconds, the alloy layer grows excessively, the tin layer decreases, the contact resistance deteriorates, and the interdiffusion of the alloy elements proceeds excessively, so that the desired nickel and zinc contents are different. A layer structure cannot be obtained.

  In addition, among these heat treatment conditions, when heat treatment is performed at a temperature of 250 ° C. or higher and 350 ° C. or lower, diffusion of zinc in the surface galvanized layer to the lower layer is suppressed, and a part of zinc remains on the surface. Thus, the metal zinc layer 8 is formed on the tin layer 5. If the temperature is less than 250 ° C., tin is not melted, so that an excessively thick metal zinc layer remains. If it exceeds 350 ° C., a desired thickness cannot be obtained due to excessive diffusion to the lower layer and oxidation of the metal zinc layer.

And the copper terminal material 1 with a tin plating manufactured in this way is shape | molded by the terminal 10 of a shape as shown, for example in FIG.
The terminal 10 is a female terminal in the example of FIG. 2, and is a connecting portion 11 into which a male terminal (not shown) is fitted from the tip, and a caulking portion caulking portion in which the exposed core wire 12 a of the electric wire 12 is caulked. 13. A covering caulking portion 14 to which the covering portion 12b of the electric wire 12 is caulked is integrally formed in this order.
FIG. 3 shows a terminal structure in which the terminal 10 is caulked to the electric wire 12, and the core caulking portion 13 is in direct contact with the core wire 12 a of the electric wire 12.

In this terminal 10, since the nickel tin zinc alloy layer 4 is formed under the tin layer 5 as described above, even if the nickel tin zinc alloy layer 4 is exposed due to the disappearance of the tin layer 5, the nickel tin zinc alloy layer 4 is exposed. Since the corrosion potential of the zinc alloy 4 is relatively close to aluminum, the occurrence of electrolytic corrosion when the core wire 12a is an aluminum core wire can be prevented.
Further, the nickel tin zinc alloy layer 4 has a two-layer structure in which the nickel content gradually decreases from the first alloy layer 6 on the substrate 2 side to the second alloy layer 7 on the surface side, thereby corroding the battery with aluminum. The corrosion resistance of the nickel tin zinc alloy layer 4 can be improved while suppressing the formation of.
Moreover, when the metal zinc layer 8 remains on the surface, since the metal zinc has a corrosion potential close to that of aluminum, the occurrence of electrolytic corrosion when coming into contact with the aluminum wire can be more effectively suppressed.
In addition, the electric wire 12 can be applied to any of a bare electric wire with a conductive wire exposed and a covered electric wire having a conductive wire as a core wire and a periphery covered with an insulating layer. In the present invention, both the bare wire and the core wire of the covered wire are referred to as an electric wire.

  The copper plate of the base material was degreased and pickled, and then subjected to nickel plating, tin plating, and zinc plating in this order. These plating layers had the thicknesses shown in Table 1. After heat treatment was performed on the copper plates with plating layers at the temperatures and times shown in Table 1, they were poured into water at 40 ° C. and subjected to cooling treatment to prepare samples. Samples 1-4, 9, 10 are examples, and samples 5-8 are comparative examples. In Comparative Example 8, galvanization was not performed, and the copper plate of the base material was degreased and pickled, and then subjected to nickel plating and tin plating in this order.

About the obtained sample, the surface metal zinc layer and the nickel tin zinc alloy layer were analyzed, and the thickness of each layer, the zinc content of the metal zinc layer, the Ni content of the nickel tin zinc alloy layer, and the Zn content were measured. did.
In these measurements, the sample was thinned to 100 nm or less using a focused ion beam device: FIB (model number: SMI3050TB) manufactured by Seiko Instruments Inc., and used as an observation sample.
This observation sample was observed at an acceleration voltage of 200 kV using a scanning transmission electron microscope: STEM (model number: JEM-2010F) manufactured by JEOL Ltd.
Regarding the thickness and concentration of the metallic zinc layer, XPS (X-ray Photoelectron Spectroscopy) analyzer ULVAC PHI model-5600LS manufactured by ULVAC-PHI Co., Ltd. was used for each sample and the sample surface was etched with argon ions. It was measured by analysis. The analysis conditions are as follows.
X-ray source: Standard MgKα 350W
Path energy: 187.85 eV (Survey), 58.70 eV (Narrow)
Measurement interval: 0.8 eV / step (Survey), 0.125 eV (Narrow)
Photoelectron extraction angle with respect to sample surface: 45 deg
Analysis area: about 800μmφ
Regarding the thickness, the “SiO ₂ equivalent film thickness” was calculated from the time required for the measurement using the etching rate of SiO ₂ measured in advance with the same model.
The etching rate of SiO ₂ is calculated by dividing the 20 nm thick SiO ₂ film by etching with argon ions in a rectangular area of 2.8 × 3.5 mm and etching 20 nm. Calculated. In the case of the above analyzer, the etching rate is 2.5 nm / min since it took 8 minutes. XPS has an excellent depth resolution of about 0.5 nm, but the etching time with the Ar ion beam varies depending on the material. Therefore, to obtain a numerical value of the film thickness, a sample with a known and flat film thickness is procured. Then, the etching rate must be calculated. Since the above is not easy, the “SiO ₂ equivalent film thickness” calculated from the time required for etching is defined by the etching rate calculated for the SiO ₂ film whose film thickness is known. Therefore, it should be noted that the “SiO ₂ equivalent film thickness” is different from the actual oxide film thickness. When the film thickness is defined by the SiO ₂ conversion etching rate, even if the actual film thickness is unknown, the film thickness is unambiguous and can be quantitatively evaluated.

FIG. 4 is a two-dimensional composition map image obtained by analyzing sample 3 using an energy dispersive X-ray analyzer attached to STEM: EDS (manufactured by Thermo), and FIG. 5 is indicated by an arrow in FIG. It is a line analysis figure of a range. NSS (ver. 3) EDS was used as analysis software.
From these figures, the sample of the example is made of nickel layer, nickel, zinc, tin from the base material side, nickel, zinc, tin, but nickel, zinc content is higher than the first alloy layer. It can be confirmed that a reduced second alloy layer is formed, and the nickel content in the alloy layer is high on the substrate side and low on the surface side. Further, a tin layer is present on the second alloy layer.
Between the first alloy layer and the nickel layer, the zinc concentration continuously increases from the nickel side toward the first alloy layer. The boundary point between the nickel layer and the first alloy layer when measuring the alloy layer thickness was the point where the slope of the zinc concentration in the line analysis diagram was the largest. In the vicinity of the boundary between the first alloy layer and the second alloy layer, the zinc concentration continuously decreases toward the second alloy layer, but the boundary point between the first alloy layer and the second alloy layer is zinc in the line analysis diagram. The point with the highest concentration gradient was taken. Similarly, the boundary point between the tin layer and the second alloy layer is also the point where the slope of the zinc concentration is the largest.
The composition of each alloy layer was a value measured using an energy dispersive X-ray analyzer attached to the STEM at the center of the alloy layer thickness.
Further, FIG. 6 is a concentration distribution diagram of each element in the depth direction on the surface portion of the sample 10 by XPS analysis. A metal zinc layer having a zinc concentration of 20 at% to 40 at% is present at a thickness of about 10 nm in terms of SiO _2. Yes. The zinc concentration of the metal zinc layer was the average value of the zinc concentration in the thickness direction at the site where 10 at% or more of metal zinc was detected by XPS.
FIG. 7 is a chemical state analysis diagram in the depth direction of the sample 10, and it can be determined that a metal zinc layer exists under a slight oxide layer on the outermost surface.

The measurement results are shown in Table 2.
In addition, since the reflow heating time was excessive, Sample 5 of the comparative example produced only a single-phase alloy layer, and the metal zinc layer was very thin. In sample 6, the heating time was short and the nickel plating thickness was thin. Therefore, the obtained second alloy layer was thin, the nickel content was low, and the galvanization thickness was excessive. A zinc layer remains. In Sample 7, since the zinc plating was thin and the heating temperature was too low, the first alloy layer and the second alloy layer did not have the desired thickness, and the zinc content was also less than the desired value. Furthermore, the metal zinc layer which did not spread | diffuse by heat processing remained. Sample 8 was not galvanized, so an alloy layer consisting only of tin and nickel was observed between the tin layer and the nickel layer.

For each sample, solder wettability, contact resistance and bending workability were evaluated.
<Solder wettability>
The solder wettability is determined by applying a flux on the sample surface under the following flux application conditions using a solder checker WET-6000 manufactured by Reska Co., Ltd. according to the soldering test method (equilibrium method) of JIS-C0053. And the wettability of lead-free solder.
(Flux application conditions)
Flux: 25% by mass rosin-ethanol, flux temperature: room temperature, flux depth: 8 mm, flux immersion time: 5 seconds, draining method: edge was applied to filter paper for 5 seconds to remove the flux.
A sample coated with this flux is fixed to the apparatus, immersed in lead-free solder in a solder bath at a depth of 1 mm at a depth of 1 mm and held for 30 seconds, and a zero cross time of 5 seconds or less is acceptable. Anything exceeding that was considered defective.

<Contact resistance>
The contact resistance measurement method conforms to JCBA-T323, using a 4-terminal contact resistance tester (manufactured by Yamazaki Seiki Laboratories: CRS-113-AU), sliding resistance (1 mm) and contact resistance at 0.98 N Was measured. Measurement was performed on the plated surface of the flat plate sample.

<Change rate of contact resistance>
The sample is processed into a terminal shape, crimped to an aluminum wire, the contact resistance between the aluminum wire and the terminal is measured, and then a salt spray test according to JIS Z 2371 is performed on the crimped portion for 24 hours, and then aluminum is again formed. The contact resistance between the wire and the terminal was measured, and the change rate of the contact resistance was calculated. As a method for measuring contact resistance, a four-terminal contact resistance tester (Yamazaki Seiki Laboratories: YMR-3) was used.
<Bending workability>
For bending workability, a test piece is cut out so that the rolling direction is long, and a load of 9.8 × 103 N is used so as to be perpendicular to the rolling direction using a W bending test jig defined in JISH3110. Bending was applied. Then, it observed with the stereomicroscope. Bending workability is evaluated as “good” when the copper alloy base material is not exposed due to cracks occurring in the bent part after the test, and the level where the copper alloy base material is exposed due to the generated cracks. Was evaluated as “bad”.
These evaluation results are shown in Table 3.

As apparent from Table 3, in the examples, the rate of change in contact resistance after the salt spray test was as low as 10% or less, and a clear electric corrosion prevention effect was observed. Among them, samples 3, 4, 9, and 10 in which the metal zinc layer is formed on the tin layer have a particularly low contact resistance change rate and a high corrosion prevention effect.
On the other hand, in the sample 5 of the comparative example, since a very thick alloy layer having a single phase was generated due to overheating, bending workability was poor, and further, the alloy layer grew excessively and the alloy layer was exposed from the tin layer. Initial contact resistance and solder wettability have deteriorated. Moreover, since the structure and composition of the alloy layer were not in the desired form, electrolytic corrosion occurred and the rate of change in contact resistance was high. In sample 6, since the nickel content was low and the tin plating thickness was thin, solder wettability was poor, and since the nickel content of the alloy layer was small and the zinc content was excessive, the alloy layer exposed to the corrosive environment It quickly disappeared, and the base substrate, nickel layer, and aluminum formed a corrosion cell, which caused electrolytic corrosion and increased the rate of change in contact resistance. In sample 7, since the thickness of the alloy layer was generally thinner than the desired value, the effect of preventing electrolytic corrosion was weak and the contact resistance change rate was 98%, which significantly deteriorated the contact resistance after the salt spray test. In sample 8, since the alloy layer did not contain zinc, the effect of preventing electrolytic corrosion was not recognized, and the contact resistance change rate was very high.

DESCRIPTION OF SYMBOLS 1 Tin terminal copper terminal material 2 Base material 3 Underlayer 4 Nickel tin zinc alloy layer 5 Tin layer 6 1st alloy layer 7 2nd alloy layer 8 Metal zinc layer 10 Terminal 11 Connection part 12 Electric wire 12a Core wire 12b Covering part 13 Core caulking part 14 Covering caulking part

Claims (7)

A base layer made of nickel or a nickel alloy, a nickel tin zinc alloy layer, a tin layer made of tin or a tin alloy are laminated in this order on a base material made of copper or a copper alloy,
The nickel-tin-zinc alloy layer has a thickness of 0.13 μm or more and 1 μm or less, nickel is contained at 15 at% or more and 60 at% or less, zinc is contained at 10 at% or more and 60 at% or less, and the balance is tin. Copper terminal material with plating.   2. The copper terminal material with tin plating according to claim 1, wherein the nickel content of the nickel tin zinc alloy layer is high on the substrate side and low on the surface side.   The nickel tin zinc alloy layer has a thickness of 0.05 μm or more, a nickel content of 25 at% or more and 60 at% or less, a zinc content of 30 at% or more and 60 at% or less, and a balance of 0.1%. A nickel alloy is contained at 15 at% or more and 40 at% or less at 08 μm or more, zinc is contained at 10 at% or more and 40 at% or less, and a second alloy layer made of tin is laminated in order from the base material side. Item 3. A copper terminal material with tin plating according to Item 2. 4. The metal zinc layer having a zinc concentration of 20 at% or more and 40 at% or less and a thickness of 3 nm or more and 30 nm or less in terms of SiO ₂ is formed on the tin layer. The copper terminal material with tin plating as described in the item.   A nickel plating step of forming a nickel or nickel alloy plating layer on the surface of a base material made of copper or copper alloy with a thickness of 0.1 μm or more and 5 μm or less; and a tin plating layer on the nickel or nickel alloy plating layer A tin plating step of forming a thickness of 3 μm to 2.0 μm, a galvanization step of forming a zinc plating layer on the tin plating layer with a thickness of 0.05 μm to 1.5 μm, and the zinc After the plating step, the substrate is heated to a temperature of 230 ° C. or more and 600 ° C. or less, a base layer made of nickel or a nickel alloy, a tin layer on the surface, and a nickel tin zinc alloy layer between the base layer and the tin layer, The manufacturing method of the copper terminal material with a tin plating characterized by having the heat processing process of forming.   6. The method for producing a tin-plated copper terminal material according to claim 5, wherein the temperature of the heat treatment step is 250 ° C. or higher and 350 ° C. or lower.   A wire terminal part structure, wherein a terminal made of a tin-plated copper terminal material according to claim 1 is crimped to a terminal of a core wire of an electric wire made of aluminum or an aluminum alloy.