JPH0855521A - Conductive member and its manufacture - Google Patents

Abstract

PURPOSE:To prevent blackening and contact resistance increase in a high- temperature environment by constructing an anti-diffusion layer from a plurality of plating layers, selecting a predetermined group of metals for each plating layer, and specifying the thickness of each plating layer. CONSTITUTION:This conductive member has base material made of copper or copper alloy and an Sn plating layer 0.1 to 0.3mum thick formed over the base material, with an air-diffusion layer formed over the Sn plating layer. The anti-diffusion layer has a plating layer 0.002 to 0.20mum thick made of a metal selected from among Au, Pt and Pd to inhibit diffusion of the Cu from the base material and to achieve chemical stability even in a high-temperature environment. The anti-diffusion layer has another plating layer 0.01 to 1.0mum thick made of a metal selected from among Ni, Cr and Ag. The anti-diffusion layer has a another plating layer 0.05 to 2.0mum thick made of a metal selected from Zn and Pb. The plating layers all inhibit diffusion of the Cu from the base material and, when used for a long time in a high-temperature environment, can reduce contact resistance to a low value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrical equipment such as terminals, connectors, relays, switches, busbars, volumes, breakers, contact springs, sockets, leadframes, etc. that can be used stably for a long period of time even under harsh environments. Electronic circuit parts or current-carrying members used as their materials,
And a manufacturing method thereof.

[0002]

2. Description of the Related Art As the electric / electronic circuit member described above, Sn-plated copper plates and copper alloy plates have been widely used. When manufacturing this type of Sn-plated plate, first, the surface of the base material is cleaned, pre-treatment such as activating the surface is performed, and further Cu undercoating is performed if necessary, followed by electrolytic or electroless plating. Method 0.5-1.
An Sn plating layer of about 5 μm is formed. This Sn-plated plate may be used as an energizing member as it is, but it is also used after being subjected to a reflow (melting) treatment to smooth the surface of the Sn-plated layer.

[0003]

[Problems to be Solved by the Invention] By the way, in recent years,
For electronic circuit parts, there is a growing demand for smaller size and higher density, which not only increases the amount of heat generated by the parts themselves due to energization, but also, for example, for parts for automobiles, from the viewpoint of securing space, etc. It is becoming more and more common to be attached to the surroundings.

However, since the surroundings of the engine of an automobile are in a harsh environment in terms of temperature, the thickness of 0.
In a current-carrying member having an Sn layer of about 5 to 1.5 μm,
There is a problem that the surface is discolored black and the contact resistance is increased to impair the stability of the electric circuit.

In order to prevent the above problems, one solution is to make the Sn plating thicker. However, if the Sn layer is made thicker, a large amount of plating powder will be generated at the time of press working, and clogging of the press die will occur. Inconvenience such as easy occurrence occurs. On the other hand, S
When the n-plating is followed by the reflow treatment, there is a limit to the formable thickness because of the treatment method of melting and solidifying the Sn plating.

Therefore, the present inventors have studied in detail the reason why the contact resistance of the Sn-plated surface becomes high in a thermal environment, and as a result, Cu in the base material or the underlying plating layer diffuses to the Sn-plated surface, It was found that formation of copper oxide or cuprous oxide was one of the causes. Therefore, suppressing the diffusion of Cu in the base material or the underlying plating layer to the surface is considered to be effective as a means for preventing an increase in contact resistance on the surface of the current-carrying member.

In order to prevent Cu from diffusing, it has been considered that a noble metal such as Au or Pt is directly plated on the surface of the substrate as a diffusion preventing layer. However, as a result of experiments conducted by the present inventors, when such a plating layer is formed on the surface of the base material, a certain thickness or more is required to sufficiently prevent Cu diffusion, resulting in high cost. It has been found.

However, when a diffusion preventing layer is formed by plating a noble metal such as Au or Pt on the Sn layer, a sufficient Cu diffusion preventing effect can be obtained even if the diffusion preventing layer is thin, and the cost is reduced. It turned out to be acceptable. Similarly, Ni, C
Even when a plating layer such as r is formed as a diffusion prevention layer on the Sn layer, a sufficient diffusion prevention effect can be obtained regardless of the thin film thickness, and in this case, the diffusion prevention layer is particularly hard, so It has been found that heat resistance can be imparted without impairing the bending characteristics required as above and the insertion / removal characteristics required as terminals and connectors. In addition, Zn on the Sn layer,
When a dissimilar metal such as Pb is plated, or when another Sn layer having a different forming method is formed on the Sn layer,
It was found that a diffusion prevention effect can be obtained.

The present invention has been made based on the above findings, and it is an object of the present invention to provide a current-carrying member capable of preventing black discoloration and increase in contact resistance in a high temperature environment and a method for manufacturing the same.

[0010]

In order to solve the above-mentioned problems, a first current-carrying member according to the present invention comprises a base material made of copper or a copper alloy, and a thickness of 0.1 formed on the base material. ~
A Sn plating layer having a thickness of 3.0 μm (hereinafter, referred to as a first Sn plating layer) and a diffusion preventing layer formed on the first Sn plating layer are provided, and the diffusion preventing layer is (a) Au, P
A plating layer having a thickness of 0.002 to 0.2 μm, which is made of one or more selected from t and Pd, and (b) Ni and C.
a plating layer having a thickness of 0.01 to 1.0 μm, which is composed of one or more selected from r and Ag, and (c) Sn and Z.
a plating layer having a thickness of 0.05 to 2.0 μm and made of one or more selected from n and Pb, and (d) a thickness of 0.
A second Sn plating layer having a thickness of 05 to 2.0 μm, and one or more plating layers selected from the following.
The thickness of the diffusion preventing layer is 2.5 μm or less.

The first Sn plating layer is formed by an electroplating method or an electroless plating method, and prevents Cu in the base material from diffusing and oxidizing on the surface of the current-carrying member, and at the same time, terminals and connectors. When used as an electric / electronic circuit component, the fitting property is improved and the energization stability is improved. However, if the thickness of the first Sn plating layer is less than 0.1 μm, the above-mentioned action cannot be sufficiently obtained, and conversely, if the thickness of the first Sn plating layer exceeds 3 μm, Sn powder is not produced when the current-carrying member is pressed. This has the disadvantage that the number of occurrences increases and clogging of the press die easily occurs. Therefore, the thickness of the first Sn plating is 0.1 to 3 μm.
I decided. More preferable thickness range is 0.3 to 2.0 μm
Is.

The plating layer (a) made of Au, Pt, Pd or the like suppresses the diffusion of Cu from the base material and
Since it is chemically stable even in a high temperature environment, it has the effect of suppressing the contact resistance when energized as an electric / electronic circuit component. However, if the thickness of the plating layer (a) is less than 0.002 μm, its action is not sufficient, while if it exceeds 0.2 μm, the burden of manufacturing cost increases, so the thickness is 0.002 to 0. It was set to 2 μm. A more preferable thickness range is 0.01 to 0.1 μm.

The plating layer (b) made of Ni, Cr, Ag or the like suppresses the diffusion of Cu from the base material and
When used as an electric / electronic circuit component in a high temperature environment for a long period of time, it has the effect of suppressing the contact resistance to a low level. However, if the thickness is less than 0.01 μm, the above effect is not sufficient. On the other hand, when the plating layer is formed of Ni or Cr and the thickness thereof exceeds 1.0 μm, cracks are likely to occur due to severe bending such as pressing. When the plating layer is formed of Ag, the thickness is 1.0
If it exceeds μm, the burden of manufacturing cost increases. Therefore, the thickness of the plating layer (b) is set to 0.01 to 1.0 μm regardless of which of Ni, Cr and Ag is used.
A more preferable thickness range is 0.03 to 0.6 μm.

The plating layer (c) made of Zn, Pb, etc.
It has an effect of suppressing Cu diffusion from the first Sn plating layer and suppressing an increase in contact resistance under a thermal environment. Zn, Pb
In both cases, if the thickness is less than 0.05 μm, the above-mentioned action is not sufficient, while the thickness is 2.
If it exceeds 0 μm, the insertion / extraction resistance when used as a terminal or a connector becomes too large, and a lot of plating powder is generated during press punching, which causes a problem. Therefore, the thickness is set to 0.05 to 2.0 μm. A more preferable thickness range is 0.3 to 1.5 μm.

When the second Sn plating layer (d) is formed as the diffusion preventing layer, it is necessary to form it by a method different from that of the first Sn plating. That is, the first Sn
When the plating layer is formed by the electrolytic plating method or the electroless plating method, the second Sn plating layer is formed by the vapor deposition method, and the first Sn plating layer is formed.
When the Sn plating layer is formed by the reflow method, the second S
The n-plated layer may be formed by an electrodeposition method or a vapor deposition method.
Possible combinations are as follows. (First Sn plating layer forming method / second Sn plating layer forming method) Wet plating method / vapor deposition method (dry plating method) Vapor deposition method / wet plating method Reflow method / wet plating method or vapor deposition method Molten Sn contact method / wet plating method or Evaporation method

If the second Sn plating layer is formed by a method different from that of the first Sn plating layer as described above, diffusion of Cu from the first Sn plating layer at the interface between the two is suppressed, resulting in black discoloration or contact resistance in a thermal environment. The effect of suppressing the increase of is obtained. However, if the thickness of the second Sn plating is less than 0.05 μm, its action is not sufficient, and conversely, if the thickness exceeds 2.0 μm, clogging of the press die is likely to occur.
Therefore, the thickness is set to 0.05 to 2.0 μm. A more preferable thickness range is 0.3 to 1.5 μm. The total thickness of the first Sn plated layer and the second Sn plated layer is preferably 3.0 μm or less.

The effect of the present invention can be obtained even when two or more kinds of the plating layers (a) to (d) satisfying the above thickness conditions are formed as a diffusion preventing layer. In that case, it is necessary that the total thickness thereof is 2.5 μm or less, and more preferably 0.02 to 1.8 μm. If the total thickness exceeds 2.5 μm, the amount of plating powder generated during press punching increases, and the press die is likely to be clogged.

In order to manufacture the above current-carrying member, the first Sn plating layer is formed on at least one of the electrolytic plating method and the electroless plating method on the base material made of copper or copper alloy. Next, on the first Sn plating layer, Au,
One or two or more metal plating layers selected from Pt, Pd, Ni, Cr, Ag, Sn, Zn, and Pb are selected from electrolytic plating method, electroless plating method, or vapor deposition method, or two or more. It may be formed by a plating method of at least one kind.

Next, the second conducting member according to the present invention will be described. The second current-carrying member includes a base material made of copper or a copper alloy and a thickness of 0.1 to 2.0 formed on the base material.
a Cu—Sn alloy layer having a thickness of μm, an Sn layer formed on the Cu—Sn alloy layer and having a thickness of 0.05 to 2.0 μm and solidified after melting, and a diffusion preventing layer formed on the Sn layer. It is equipped with. The diffusion prevention layer is the same as that of the first current-carrying member, so description thereof will be omitted.

The thickness of the Cu—Sn alloy layer is 0.1 μm.
Or the thickness of the Sn layer solidified after melting is 0.05
If the thickness is less than μm, it is not possible to sufficiently suppress the diffusion and oxidation of Cu in the base material to the surface of the current-carrying member, and the fitting property deteriorates when used as electric / electronic circuit parts such as terminals and connectors. , The energization stability decreases.

On the other hand, the thickness of the Cu—Sn alloy layer is 2.0 μm.
If it exceeds m, the amount of Cu that diffuses from the Cu—Sn alloy layer to the Sn layer in a thermal environment increases, which adversely affects the heat resistance of the plating. In addition, the thickness of the Sn layer solidified after melting is 2.0 μm.
When it exceeds m, generation of Sn powder during pressing and clogging of scraps in the mold are likely to occur. Therefore, the thickness of the Cu—Sn alloy layer was set to 0.1 to 2.0 μm, and the thickness of the Sn layer solidified after melting was set to 0.05 to 2.0 μm. More preferably 0.3 to 1.2 μm and 0.15 to 1.2 μm, respectively
Is.

In order to manufacture the second current-carrying member having the above structure, first, a Sn plating layer is formed on a base material made of copper or a copper alloy by at least one of electrolytic plating method and electroless plating method. Form. The thickness of the Sn plating layer before reflow is preferably less than 3 μm. If it exceeds 3 μm, dripping tends to occur at the time of melting, and reflow treatment becomes difficult.

Then, the base material is subjected to a reflow treatment to form a Cu-Sn alloy layer on the surface of the base material, and a Sn layer which is solidified after melting is formed thereon. The reflow treatment may be a commonly used method, specifically, 240 to 400 ° C. in a heating furnace filled with an inert gas.
You can heat it up.

Subsequently, Au, Pt, and the like are deposited on the Sn layer solidified after melting by one or more plating methods selected from an electrolytic plating method, an electroless plating method or a vapor deposition method.
One or more metal plating layers selected from Pd, Ni, Cr, Ag, Sn, Zn, and Pb may be formed with the above-described thickness.

As another method of manufacturing the second current-carrying member,
By contacting a base material made of copper or a copper alloy with molten Sn, a Cu—Sn alloy layer may be formed on the surface of the base material and a Sn layer solidified after melting may be formed thereon. Specifically, a method such as immersing the base material in Sn in a molten state at 250 to 400 ° C. is possible.

After that, in the same manner as the above method, the S solidified after melting was solidified.
Au, Pt, Pd, Ni, Cr, Ag, Sn, Z are formed on the n layer by one or more plating methods selected from an electrolytic plating method, an electroless plating method, or a vapor deposition method.
It suffices to form one or more metal plating layers selected from n and Pb.

In the first or second current-carrying member, a Cu undercoat layer having a thickness of 0.1 to 1.0 μm may be formed on the surface of the base material. In order to form such a Cu undercoat layer, a base material obtained by plating Cu or a copper alloy base material with Cu undercoat may be used and the above-described manufacturing method may be performed. When the base material is pure copper, brass (Cu-Zn alloy) or other copper alloy, by forming a Cu undercoat layer, the glossiness, smoothness, and smoothness of the Sn plating layer formed thereon can be improved.
Adhesion and the like can be improved. If the thickness of the Cu undercoat layer is less than 0.1 μm, the above-mentioned action becomes insufficient. On the other hand, even if the thickness of the Cu undercoat layer exceeds 1.0 μm, the above effect is not further improved, and plating production It only deteriorates the sex. Therefore, the thickness of the Cu undercoat is preferably 0.1 to 1.0 μm.

However, for example, phosphor bronze (4-8% Sn)
When a special copper alloy such as Cu alloy) is used as the base material, the formation of the Cu undercoat layer adversely affects the heat resistant adhesion of the Sn plating layer. It is necessary to use them properly according to the type of material.

[0029]

In the current-carrying member according to the present invention, regardless of the type of copper alloy forming the base material, copper can be prevented from diffusing from the base material to the surface of the current-carrying member even under a severe thermal environment, which results from copper diffusion. Problems such as discoloration and increase in contact resistance can be prevented.
Therefore, even when placed in a harsh environment such as around an automobile engine as an electric / electronic circuit component,
High reliability can be obtained over a long period of time.

Further, according to the method of manufacturing the current-carrying member of the present invention, the excellent current-carrying member can be easily manufactured.

[0031]

EXAMPLES Next, the effects of the present invention will be specifically described with reference to examples. Substrates a to n having the composition shown in Table 1 were produced by an ordinary copper plate or copper alloy plate production facility. As the base materials j, k and l, commercially available phosphor bronze plates preliminarily subjected to hot-dip Sn plating were used.

[0032]

[Table 1]

A Cu undercoat layer was formed on the surfaces of the base materials a to n by electrolytic plating or electroless plating, if necessary, and then an Sn plating layer was formed. Further, some substrates were subjected to reflow treatment under various conditions in a furnace filled with an inert gas, and the Sn coating was once melted to smooth the surface.

Au, Pt, Pd, Ni, Cr, A is formed on the Sn plating layer or the solidified Sn layer thus formed by a vacuum deposition method, an electrolytic plating method or an electroless plating method.
Samples 1 to 32 were formed by forming one or more metal films selected from g, Zn, Sn, and Pb. Tables 2 and 3 show these film configurations. In each table, (Electric) indicates that the film was formed by the electrolytic plating method, (None) indicates the electroless plating method, and (Steam) indicates that the film was formed by the vapor deposition method. Further, the film thickness of each plating layer was measured using a means such as an electrolytic film thickness meter (Kokur film thickness meter), a fluorescent X-ray film thickness meter, or a cross-section SEM observation. The measured values are also shown in Tables 2 and 3. Each measured value is an average value of 5 measurements.

(Contact resistance test) From each sample, width: 40 m
m × length: 40 mm of each test piece was cut out, and the tip was gold-plated, diameter: 3 mm, radius of curvature of the tip was 1.5
A mm probe was brought into contact with the surface of the test piece with a contact load of 50 g, and the contact resistance was measured 10 times. Furthermore, after heating each test piece in the air at a temperature of 160 ° C. for 500 hours, the contact resistance of the test piece after heating was measured 10 times under the same conditions, and the difference in the average value of the contact resistance before and after heating was calculated as the contact resistance. It was calculated as the increase amount. The results are shown in Tables 2 and 3.

[0036]

[Table 2]

[0037]

[Table 3]

As is clear from Tables 2 and 3, the comparison product showed an increase in contact resistance of 200 mΩ or more, regardless of the type of the substrate and the presence or absence of the Cu underlayer, whereas the product of the present invention had an increase of 35 mΩ or less. was. In particular, it was found that the product of the present invention can effectively prevent an increase in contact resistance under a severe thermal environment of 160 ° C. even when the thickness of the Sn layer is smaller than that of the comparative product.

[0039]

As described above, in the current-carrying member according to the present invention, regardless of the kind of copper alloy forming the base material,
Copper can be prevented from diffusing from the base material to the surface of the current-carrying member even under a severe thermal environment, and problems such as discoloration and increase in contact resistance due to copper diffusion can be prevented. So, for example, electricity
Even when placed in a harsh environment such as around an engine of an automobile as an electronic circuit component, high reliability can be obtained for a long time.

Further, according to the method of manufacturing the current-carrying member of the present invention, the excellent current-carrying member can be easily manufactured.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01R 13/03 A

Claims (7)

[Claims] 1. A base material made of copper or a copper alloy, an Sn plating layer having a thickness of 0.1 to 3.0 μm formed on the base material, and a diffusion prevention layer formed on the Sn plating layer. And the diffusion prevention layer is selected from Au, Pt, and Pd.
Or a thickness of 0.002 to 0.2.
μm plated layer, one or two or more selected from Ni, Cr and Ag, and a plating layer having a thickness of 0.01 to 1.0 μm, and one or two or more selected from Zn and Pb. One or more platings selected from a plating layer having a thickness of 0.05 to 2.0 μm and a Sn plating layer having a thickness of 0.05 to 2.0 μm formed by a method different from that of the Sn plating layer. A current-carrying member comprising a layer, wherein the diffusion prevention layer has a thickness of 2.5 μm or less. 2. A base material made of copper or a copper alloy, and Cu—Sn having a thickness of 0.1 to 2.0 μm formed on the base material.
An alloy layer, an Sn layer formed on the Cu—Sn alloy layer and having a thickness of 0.05 to 2.0 μm and solidified after melting, and a diffusion prevention layer formed on the Sn layer. The diffusion prevention layer is selected from Au, Pt and Pd 1
Or a thickness of 0.002 to 0.2.
μm plated layer, one or two or more selected from Ni, Cr, and Ag and a thickness of 0.01 to 1.0 μm, or one or two selected from Zn and Pb.
A plating layer having a thickness of 0.05 to 2.0 μm, which is made of one or more seeds,
And one or two or more plating layers selected from a Sn plating layer having a thickness of 0.05 to 2.0 μm formed by a method different from that of the Sn plating layer, and a thickness of the diffusion preventing layer. The current-carrying member is characterized by having a length of 2.5 μm or less. 3. The current-carrying member according to claim 1 or 2, wherein the surface of the base material has a thickness of 0.1 to 1.0 μm of C.
u A current-carrying member having an undercoat plating layer formed thereon. 4. A step of forming a Sn plating layer on at least one of an electrolytic plating method and an electroless plating method on a base material made of copper or a copper alloy, and Au, Pt, Pd, Ni, C
1 or 2 or more kinds of metal plating layers selected from r, Ag, Sn, Zn, Pb are formed by 1 or 2 or more kinds of plating methods selected from electrolytic plating method, electroless plating method or vapor deposition method. And a step of forming the conductive member. 5. A step of forming an Sn plating layer on a base material made of copper or a copper alloy by at least one of an electrolytic plating method and an electroless plating method, and a reflow treatment of the base material to thereby form the base material. A step of forming a Cu-Sn alloy layer on the surface and forming a Sn layer that is solidified after melting on the Cu layer; and one type selected from an electrolytic plating method, an electroless plating method or a vapor deposition method on the Sn layer, or Au, Pt, Pd, Ni, Cr, Ag, Sn,
And a step of forming one or more metal plating layers selected from Zn and Pb. 6. A base material made of copper or a copper alloy is melted with S.
Cu-Sn on the surface of the base material by bringing it into contact with n.
Sn that forms an alloy layer and is solidified after melting on it
A step of forming a layer, and Au, Pt, Pd, Ni, Cr, Ag on the Sn layer by one or more plating methods selected from an electrolytic plating method, an electroless plating method or a vapor deposition method. , Sn,
And a step of forming one or more metal plating layers selected from Zn and Pb. 7. The method for producing a current-carrying member according to claim 4, 5 or 6, wherein the base material is a copper or copper alloy base material on which a Cu undercoat layer is formed. And a method for manufacturing a current-carrying member.