JP2020190007A - Method of producing plated laminate, and plated laminate - Google Patents

Abstract

To provide a method of producing a plated laminate excellent in oxidation resistance and electroconductivity, and a plated laminate.SOLUTION: The method of producing a plated laminate is characterized by comprising a nickel plating process of applying underlying nickel plating at least onto a part of the surface of a metal base material to form an underlying nickel plating layer, an alloy layer forming process of forming a nickel/tin alloy layer at least on a part of the surface of the underlying nickel plating layer, and a tin plating process of applying tin plating at least onto a part of the surface of the nickel/tin alloy layer to form a tin plating layer.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a plated laminate and a plated laminate, and more specifically, to a method for producing a plated laminate having excellent oxidation resistance and conductivity and a plated laminate.

The tin-plated material with nickel base plating is widely used as a material for connection terminals for general-purpose products because it can be manufactured at low cost. In many cases, for the purpose of preventing whiskers that cause short circuits in conductive circuits, the material is tin-plated and then heat-treated such as reflow treatment to form an alloy layer under the tin plating. It suppresses alloying over time due to metal diffusion of the base plating.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-40649), a tin-nickel alloy layer is formed by performing a reflow treatment on a plating laminate in which a nickel plating layer and a tin plating layer are laminated in this order on the surface of a base material. A structure to be formed has been proposed.

According to the plating laminate described in Patent Document 1, the tin-nickel alloying is carried out over time by interposing a tin-nickel plating alloy layer between the underlying nickel plating layer and the tin plating layer. It is said that it can suppress the growth toward the plating side.

Japanese Unexamined Patent Publication No. 2014-40649 Japanese Unexamined Patent Publication No. 2016-169439

However, in the plating laminate described in Patent Document 1, the formation of the alloy layer formed between the base plating and tin and on the surface of the base material can be controlled in the heat treatment performed in the reflow treatment for forming the alloy layer. Instead, the alloy layer formed of the base plating metal and tin reaches the outermost layer. Since the alloy layer reaching the outermost layer reacts with oxygen in the air and is easily oxidized, a decrease in conductivity becomes a problem.

That is, conventionally, there has been a demand for a technique of controlling the formation of an alloy layer of a base plating metal and tin to maintain the conductivity of a plated laminate.

In view of the above problems in the prior art, the present invention provides a method for producing a plated laminate having excellent corrosion resistance, oxidation resistance, and conductivity, and a method for producing a plated laminate.

It is extremely effective for the present inventor to include an independent step of forming an alloy layer as a result of intensive research on a method of base plating and tin plating on a metal base material in order to achieve the above object. And arrived at the present invention.

That is, the present invention
This is a method for manufacturing a plated laminate in which a metal base material is plated in a laminated manner.
A nickel plating process in which at least a part of the surface of a metal substrate is plated with a base nickel to form a base nickel plating layer,
An alloy plating layer forming step of forming a nickel-tin alloy plating layer on at least a part of the surface of the base nickel plating layer,
A tin plating step of forming a tin plating layer by tin plating at least a part of the surface of the nickel tin alloy plating layer,
Provided is a method for producing a plated laminate, which comprises the above.

In the method for producing a plated laminate of the present invention, the thickness of the alloy layer can be freely adjusted by including a step of forming an alloy layer of the base nickel plating and tin, and the alloy layer reaches the outermost layer. Can be prevented.

In the method for producing a plated laminate of the present invention, as an alloy forming treatment, a method of forming tin plating on the surface of the underlying nickel plating and heating the tin plating may be used, or a method of performing a nickel-tin alloy plating treatment may be used. Good.

In the method for producing a plated laminate of the present invention, a discoloration prevention treatment may be performed after the tin plating step. By applying the discoloration prevention treatment, it is possible to form a plated laminate having aesthetic appearance and commercial strength.

Further, in the method for producing a plated laminate of the present invention, it is preferable that the thickness of the nickel-tin alloy plating layer is 0.1 to 5 μm.

By setting the thickness of the nickel-tin alloy plating layer to 0.1 μm or more, it is possible to obtain a sufficient effect of suppressing the formation of an alloy with nickel during the tin plating treatment applied to the surface thereof. Further, by setting the thickness of the nickel-tin alloy plating layer to 5 μm or less, it is possible to form a sufficient thickness for the tin plating layer applied to the surface thereof.

According to the method for producing a plated laminate of the present invention, the thickness of the alloy layer can be freely adjusted by including the step of forming an alloy layer of the base nickel plating and tin, and the alloy layer reaches the outermost layer. You can prevent that. As a result, a plated laminate having excellent conductivity can be obtained.

It is a process drawing of one Embodiment of the manufacturing method of the plating laminate of this invention. It is the schematic sectional drawing which shows an example of the plating laminate of this invention. It is a conceptual diagram which shows the structure of the plating laminate obtained in the Example and the comparative example of this invention. 6 is a surface SEM image of the nickel-tin alloy layer in the plating materials obtained in Examples 1 and 2 and Comparative Example 1. It is a cross-sectional profile of the surface roughness of the nickel-tin alloy layer in the plating materials obtained in Examples 1 and 2 and Comparative Example 1.

Hereinafter, typical embodiments of the plated laminate of the present invention and the method for producing the same will be described in detail with reference to the drawings, but the present invention is not limited to these. In the following description, the same or corresponding parts may be designated by the same reference numerals, and duplicate description may be omitted. Moreover, since the drawings are for conceptually explaining the present invention, the dimensions of each component represented and their ratios may differ from the actual ones.

≪Manufacturing method of plated laminate≫
FIG. 1 is a process diagram of an embodiment of the method for manufacturing a plated laminate of the present invention. The method for producing a plated laminate of the present embodiment is a method for producing a plated laminate in which a metal base material is laminated and plated, and mainly includes the following steps. In the following, each step (see FIG. 1) of the present embodiment including these main steps will be described in detail.

-Nickel plating step (S02) of forming a base nickel plating layer by applying base nickel plating to at least a part of the surface of a metal base material.
-Alloy plating layer forming step (S03) of forming a nickel-tin alloy layer on at least a part of the surface of the base nickel plating layer.
-A tin plating step (S04) in which at least a part of the surface of the nickel-tin alloy plating layer is tin-plated to form a tin-plated layer.

(1) Cleaning process (S01)
It is preferable to wash the metal substrate as a preliminary treatment prior to the entire process. The cleaning method for the metal substrate is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known cleaning methods can be used. As the cleaning treatment liquid, for example, a general immersion degreasing liquid for non-ferrous metals or an electrolytic degreasing liquid can be used.

The metal used for the metal base material is not particularly limited as long as it has conductivity, and is, for example, aluminum and aluminum alloy, iron and iron alloy (for example, iron-nickel alloy), titanium and titanium alloy, stainless steel, and copper. And copper alloys and the like, but among them, copper and copper alloys are preferably used because they are excellent in conductivity, thermal conductivity and spreadability.

(2) Base nickel plating treatment (S02)
As the nickel plating bath, one containing a nickel salt, a conductive salt, and a pH buffer can be used. In addition, a chelating agent, a surfactant, and a brightening agent may be added.

As the nickel salt, for example, nickel chloride, nickel sulfate, nickel sulfamate and the like can be used. As the conductive salt, for example, sulfuric acid, nickel chloride, ammonium chloride, ammonium sulfate, sodium hydroxide and the like can be used. As the pH buffer, for example, citric acid, boric acid and the like can be used. As the chelating agent, for example, pyrophosphoric acid, citric acid, ethylenediaminetetraacetic acid and the like can be used. As the surfactant, for example, sodium lauryl sulfate, polyoxyethylene alkyl ether and the like can be used. As the brightener, for example, saccharin, naphthalene, sodium sulfonate, sulfonamide, butynediol, coumarin and the like can be used.

Conditions such as the bath temperature of the nickel plating bath, the anode material, and the current density can be appropriately set according to the plating bath to be used, the required plating thickness, and the like. For example, a nickel-soluble anode or the like can be used as the anode material. Further, suitable conditions, bath temperature: 20 to 50 ° C., a current density ^{_{1~30A / d m 2, pH:}} 2.0~5.0 can be presented.

(3) Alloy plating layer forming treatment (S03)
As described above, in the present invention, as the alloy forming treatment, (a) a method of forming tin plating on the surface of the base nickel plating and heating the tin plating may be used, or (b) nickel tin alloy plating treatment is performed. It may depend on the method.

(A) The method of forming tin plating on the surface of the base nickel plating and heating the tin plating includes a tin plating treatment for diffusion and a heat treatment.

(A-1) Diffusion tin plating treatment The diffusion tin plating treatment is a part of the alloy plating layer forming treatment step performed in combination with the heat treatment, and is a step selectively performed with the nickel tin alloy plating treatment.

As the diffusion tin plating bath, one containing a tin salt and a conductive salt can be used. Further, a chelating agent and an additive may be added. As the tin salt, for example, tin chloride, tin sulfate, tin oxide, potassium tinate, sodium tint and the like can be used. As the conductive salt, for example, sulfuric acid, hydrochloric acid, potassium hydroxide, sodium hydroxide and the like can be used. As the chelating agent, for example, pyrophosphoric acid, citric acid, ethylenediaminetetraacetic acid and the like can be used. As the additive, for example, UTB-530M, ST-10, etc. manufactured by Ishihara Chemical Co., Ltd. can be used.

Conditions such as the bath temperature of the tin plating bath, the anode material, and the current density can be appropriately set according to the plating bath used and the required plating thickness. For example, a tin-soluble anode or the like can be used as the anode material. Further, as suitable conditions, a bath temperature of 10 to 60 ° C. and a current density of 0.1 to 10 A / dm ² can be presented.

The thickness of the tin plating layer formed by the diffusion tin plating treatment is preferably 0.1 to 5 μm. By setting the thickness of the tin plating layer to 0.1 μm or more, it is possible to obtain a sufficient effect of suppressing the formation of an alloy with nickel during the tin plating treatment applied to the surface thereof. Further, by setting the thickness of the tin-plated layer to 5 μm or less, it is possible to further form a sufficient thickness of the tin-plated layer to be applied to the surface after the alloy is formed.

(A-2) Heat treatment In the temperature range where metal diffusion progresses between the base nickel plating and the tin plating, heating is performed until the alloy layer grows to the outermost layer. The heating method is not particularly limited as long as the effect of the present invention is not impaired, and various conventionally known heating methods can be used. Specifically, hot air heating, hot plate heating, heating in an atmospheric atmosphere by a heating furnace, and heating in a reducing atmosphere by a heating furnace may be used. As the heating conditions, it is preferable that the heating temperature is 80 to 500 ° C. and the heating time is 5 seconds to 3600 seconds.

(B) In the method of performing the nickel-tin alloy plating treatment, the nickel-tin alloy plating treatment is performed. This nickel-tin alloy plating treatment is a step (a) of undergoing the above-mentioned diffusion tin plating treatment and heat treatment, and an alloy plating layer forming step selectively performed.

As the nickel-tin alloy plating bath, one containing a tin salt, a nickel salt, a conductive salt, and a pH buffer can be used. In addition, a chelating agent, a surfactant, and a brightening agent may be added.

As the nickel salt, for example, nickel chloride, nickel sulfate, nickel sulfamate and the like can be used. As the tin salt, for example, tin chloride, tin sulfate, tin oxide, potassium tinate, sodium tint and the like can be used. As the pH buffer, for example, citric acid, boric acid and the like can be used. As the chelating agent, for example, pyrophosphoric acid, citric acid, ethylenediaminetetraacetic acid and the like can be used. As the surfactant, for example, sodium lauryl sulfate, polyoxyethylene alkyl ether and the like can be used. As the brightener, for example, saccharin, naphthalene, sodium sulfonate, sulfonamide, butynediol, coumarin and the like can be used.

Conditions such as the bath temperature, anode material, and current density of the nickel-tin alloy plating bath can be appropriately set according to the plating bath to be used and the required plating thickness. For example, a nickel / tin-soluble anode or the like can be used as the anode material. Further, suitable conditions, bath temperature: 20 to 50 ° C., a current density ^{_{1~30A / d m 2, pH:}} 2.0~5.0 can be presented.

(6) Tin plating treatment (S04)
As the tin plating bath, a bath containing a tin salt and a conductive salt can be used. Further, a chelating agent and an additive may be added.

As the tin salt, for example, tin chloride, tin sulfate, tin oxide, potassium tinate, sodium tint and the like can be used. As the conductive salt, for example, sulfuric acid, hydrochloric acid, potassium hydroxide, sodium hydroxide and the like can be used. As the chelating agent, for example, pyrophosphoric acid, citric acid, ethylenediaminetetraacetic acid and the like can be used. As the additive, for example, UTB-530M, ST-10, etc. manufactured by Ishihara Chemical Co., Ltd. can be used.

Conditions such as the bath temperature of the tin plating bath, the anode material, and the current density can be appropriately set according to the plating bath used and the required plating thickness. For example, a tin-soluble anode or the like can be used as the anode material. Further, suitable conditions, bath temperature: 10 to 60 ° C., it is possible to present the current density 0.1~10A _{/ d} ^{m 2.}

The thickness of the tin-plated layer formed by the tin-plating treatment is preferably 0.1 to 5 μm. By setting the thickness of the tin-plated layer to 0.1 μm or more, the conductivity derived from tin can be ensured. Further, by setting the thickness of the tin plating layer to 5 μm or less, the amount of tin used can be suppressed.

≪Plated laminate≫
The plating laminate obtained by the method for producing a plating laminate of the present invention as described above includes a metal base material, a base nickel plating layer provided on at least a part of the surface of the metal, and the base nickel plating layer. It is characterized by including a nickel-tin alloy layer provided on at least a part of the surface of the nickel-tin alloy plating layer, and a tin-plated layer provided on at least a part of the surface of the nickel-tin alloy plating layer.

In this plated laminate, the nickel-tin alloy layer is controlled to have a more uniform thickness and does not reach the outermost layer due to its growth, so that it has oxidation resistance and maintains conductivity. Further, the nickel-tin alloy layer in the present invention has a property of suppressing further metal diffusion after film formation by adopting an alloy composition of Ni ₃ Sn ₄ , and is compared with a general reflow treatment. The surface roughness is smooth, and by forming a tin plating after forming the nickel-tin alloy layer, the distance from the nickel-tin alloy layer to the outermost tin plating layer (thickness of the pure tin layer) can be determined. It is possible to hold it uniformly.

Although the typical embodiments of the present invention have been described above, the present invention is not limited to these, and various design changes are possible, and all of these design changes are included in the technical scope of the present invention. ..

<< Example 1 >>
A plated laminate was produced according to the process shown in FIG. 1 except for the fifth step (discoloration prevention treatment).
First, the copper substrate was washed with an alkaline degreasing solution (S01), and a nickel bath containing 500 g / L nickel sulfamate, 10 g / L nickel chloride, and 40 g / L boric acid was used to obtain 0.5 μm. A base plating treatment was performed to form a nickel plating layer (S02).
Then, tin plating was carried out using a tin plating bath containing 100 g / L of sodium tinate and 15 g / L of sodium hydroxide, and then heated at 300 ° C. for 30 seconds to a thickness of 0.2 μm. A nickel-tin alloy plating layer was formed (S03).
Further, a tin plating bath having a thickness of 1.0 μm was formed on the surface of the nickel-tin alloy plating layer using a tin plating bath containing 70 g / L stannous sulfate, 80 g / L sulfuric acid, and 15 mL of additives. (S04), a plated laminate (plating material) was obtained.

<< Example 2 >>
A plated laminate was produced in the same manner as in Example 1 except that a nickel-tin alloy plating layer having a thickness of 0.2 μm was formed and a tin plating layer having a thickness of 0.7 μm was formed on the surface thereof.

<< Example 3 >>
Regarding the heat treatment for forming the nickel-tin alloy, a plating material was prepared in the same manner as in Example 1 except that the heating temperature was 500 ° C. and the heating time was 5 seconds.

<< Example 4 >>
Regarding the heat treatment for forming the nickel-tin alloy, a plating material was produced in the same manner as in Example 1 except that the heating temperature was 80 ° C. and the heating time was 3600 seconds.

<< Comparative Example 1 >>
The copper substrate was washed and subjected to a base nickel plating treatment. Then, tin plating treatment was performed to form tin plating having a thickness of 1.2 μm. Further, a plating material was prepared by heating on a hot plate under the conditions of a heating temperature of 300 ° C. and a heating time of 30 seconds (reflow treatment).

≪Comparative example 2≫
A plating material was produced in the same manner as in Comparative Example 1 except that the reflow treatment was not performed after the tin plating treatment.

≪Comparative example 3≫
A plating material was produced in the same manner as in Comparative Example 1 except that the base nickel plating treatment was not performed.

[Evaluation test]
(1) Evaluation of alloy layer formation amount The alloy layer formation amount was evaluated for each of the plating materials prepared as described above. The plating material was immersed in a solution consisting of sodium hydroxide and p-nitrophenol, and only the pure tin layer was dissolved to prepare a sample for measurement. Then, in this sample, the abundance of tin after peeling was measured using a fluorescent X-ray film thickness meter. The results are shown in Table 1. In Table 1, the amount of tin contained in the alloy layer is determined by using a stripping solution consisting of p-nitrophenol and sodium hydroxide to strip only the pure tin layer, and then tin is measured with a fluorescent X-ray film thickness meter. The value converted to the film thickness by the method of measuring the film thickness of the plating is shown.

(2) Evaluation of surface condition of alloy layer The maximum height roughness Rz of the surface of the sample was measured with a laser microscope. The results are shown in Table 1.
(3) Evaluation of whisker generation The sample was heated under the conditions of temperature: 85 ° C. and humidity: 85% for 66 hours, and then the surface was observed to confirm the presence or absence of whisker generation. Table 1 shows the results as "○" when whiskers have not occurred and "x" when whiskers have occurred.
(4) Measurement of electrical contact resistance For sample 2 obtained by heating under the conditions of temperature: 140 ° C. and time: 7 days, the probe used: SK material and nickel base gold plating, measurement start load: 0. The electrical contact resistance was measured under the conditions of 5N, measurement end load: 40N, and number of measurements: 10 times. The results are shown in Table 1.

From the results shown in Table 1, in each of the examples of the present invention, the electrical contact resistance was 5Ω or less, and better results were obtained as compared with the comparative example not including the step of forming the nickel-tin alloy plating layer. ing. Further, in the embodiment of the present invention, the maximum height roughness value is 0.601 μm or less, which is smoother than the value of 0.955 μm or more when the step of forming the nickel-tin alloy plating layer is not included. It can be confirmed that it is in a good state. That is, as shown in the conceptual diagram of FIG. 3, the nickel-tin alloy layer of the plating material of the example is smoother than that of the plating material of the comparative example (note that in FIG. 3, the metal base material is "copper or copper alloy". ").

For reference, in FIG. 4, in the plating materials of Examples 1 and 2 and Comparative Example 1, a surface SEM image of the nickel-tin alloy layer was taken after (1) of the above evaluation test, and nickel tin was also taken. A cross-sectional profile of the surface roughness of the alloy layer was created. The results are shown in FIGS. 4 and 5. From these, it can be seen that the nickel-tin alloy layer of the plating material of the example is smoother than that of the plating material of the comparative example.

Further, in Comparative Example 2, although the step of forming the nickel-tin alloy plating layer is not included, the alloy layer is formed slightly, and the alloy layer is formed by metal diffusion between nickel-tin due to aging at room temperature. It is suggested that the formation is progressing. In addition, the occurrence of whiskers has not been confirmed in the examples, and it is considered that excellent product stability can be maintained when the production method of the present invention is used.

1 ... Plating laminate 2 ... Metal base material (copper or copper alloy base material)
4 ... Base nickel plating layer 6 ... Nickel tin alloy plating layer 8 ... Tin plating layer

Claims (6)

A nickel plating process in which at least a part of the surface of a metal substrate is plated with a base nickel to form a base nickel plating layer,
An alloy layer forming step of forming a nickel-tin alloy plating layer on at least a part of the surface of the base nickel plating layer,
A tin plating step of forming a tin plating layer by tin plating at least a part of the surface of the nickel tin alloy plating layer,
A method for producing a plated laminate, which comprises. In the alloy plating layer forming step, at least a part of the surface of the base nickel plating layer is tin-plated to form a diffusion tin plating layer, and heat treatment is performed to perform the base nickel plating layer and the diffusion. It is a step of forming a nickel-tin alloy layer by diffusing the tin-plated layers with each other.
The method for producing a plated laminate according to claim 1. The alloy plating layer forming step is a step of forming a nickel tin alloy layer by subjecting at least a part of the surface of the base nickel plating layer to nickel tin alloy plating.
The method for producing a plated laminate according to claim 1. The thickness of the nickel-tin alloy plating layer is 0.1 to 5 μm.
The method for producing a plated laminate according to any one of claims 1 to 3. After the tin plating step, a discoloration prevention step of applying a discoloration prevention treatment is included.
The method for producing a plated laminate according to any one of claims 1 to 4. With a metal base material
An underlying nickel-plated layer provided on at least a part of the surface of the metal,
A nickel-tin alloy layer provided on at least a part of the surface of the base nickel plating layer, and
A tin plating layer provided on at least a part of the surface of the nickel-tin alloy plating layer,
A plated laminate characterized by containing.