JP2002317295A - Reflow treated Sn alloy plating material, fitting type connection terminal using the same - Google Patents

Abstract

(57) [Problem] To provide a material excellent in slidability, solderability and corrosion resistance, and a fitting connection terminal using the same. A surface layer (2) formed on the surface of a conductive substrate (1) has at least one selected from the group consisting of an electroplating layer of Sn or a Sn alloy and Ag, Bi, Cu, In, and Zn further covering the electroplating layer. A reflow-processed Sn alloy plating material, which is a reflow-processed layer formed by performing a reflow process on an electroplating layer of a kind metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow-processed Sn alloy plating material and a fitting connection terminal using the same, and more particularly, to a reflow process having excellent surface slidability, solderability, and corrosion resistance. The present invention relates to a Sn alloy plating material and a fitting connection terminal using the same.

[0002]

2. Description of the Related Art A material in which an Sn layer is provided on the surface of a conductive substrate made of Cu or Cu alloy has excellent conductivity and mechanical strength of Cu or Cu alloy, and has good electrical contact with Sn. It is a high-performance conductor having characteristics, solderability, and corrosion resistance, and is widely used in fields such as leads of capacitors and semiconductor chips, various terminals, connectors, and electric wires.

In the above-mentioned materials, the Sn layer is usually formed by electroplating pure Sn. In this case, since the internal stress of the plating layer is large, whiskers of Sn are easily generated, and short-circuiting by the whiskers is caused. Accidents may occur. Further, since the structure of the Sn layer is fine,
For example, the components of the conductive substrate may diffuse to the surface of the Sn layer due to heat at the time of soldering, which may cause problems such as deterioration of solderability and deterioration of corrosion resistance. Furthermore, S
Since n is soft, it is inferior in wear resistance, and when the surface of the mating material is also composed of the Sn layer, cohesive wear and abrasive wear occur when sliding between them, and the dynamic friction coefficient increases. , A decrease in wear resistance occurs.

On the other hand, the above-mentioned Sn layer is formed of, for example, Sn-A
Substitution with an Sn alloy layer such as g, Sn—Bi, or Sn—Pb has the advantage that whiskers are less likely to occur in the Sn alloy layer and that the wear resistance is improved. However, when the Sn alloy layer is formed by the electroplating method, the alloy composition in the formed Sn alloy layer varies even if the conditions of the plating bath and the current conditions are slightly changed. It is difficult to form a layer stably. Further, it is possible to form the Sn alloy layer by a hot-dip plating method instead of the electroplating method, but in that case, it is difficult to control the plating thickness to be small, and the plating thickness becomes large. Occurs. A thicker plating thickness means a higher sliding resistance, which is disadvantageous, for example, in the case of a connector requiring a low sliding resistance.

In order to solve the above-mentioned problem in a material whose surface layer is made of a Sn layer or a Sn alloy layer, JP-A-2000-2000
Japanese Patent Publication No. -150008 discloses the following materials. That is, an Sn layer is formed on the surface of a conductive substrate, and an extremely thin B layer is formed on the Sn layer by a substitution deposition method.
After the i-layer and / or the Ag layer is formed, the whole is subjected to a reflow treatment to convert the vicinity of the surface of the Sn layer into a Sn alloy layer.

[0006]

However, recent research has revealed that the above-mentioned prior art has the following problems. First, when the Bi layer and / or the Ag layer is formed on the Sn layer by the substitution deposition method, the speed of the substitution reaction is rapidly reduced once the surface of the Sn layer is coated with Bi or Ag. In other words, the time required to replace a certain amount is very long, and the productivity is extremely low.

Further, in the case of the displacement deposition method, a metal whose deposition potential is lower than that of Sn may not be deposited on the Sn layer in principle. In particular, the former problem is
This is an important problem for the material of the fitting connection terminal represented by the connector terminal. That is, in the case of the fitting type connection terminal, the male terminal and the female terminal are fitted to each other to realize the electrical connection. Sliding fit. Therefore, in each terminal, the surface layer is the Sn alloy layer described above over a certain thickness,
At the time of mating sliding, Sn layer or S layer located under the surface layer
It is necessary that the n alloy layer is not removed. However, since the Sn alloy layer in the vicinity of the surface in the prior art described above is very thin, it is difficult to meet the above-mentioned requirements. However, there is a problem in that the resistance is large and the slidability cannot be reduced.

In recent connectors, the number of terminals has increased. For this reason, the resistance between the terminals at the time of mating sliding is larger than before, but the magnitude of the resistance greatly affects the workability at the time of assembling the connector. For example, when the resistance is large, a large amount of time is required for the assembling work. In order to reduce the resistance at the time of the sliding of the fitting, the thickness of the Sn layer or the Sn alloy layer on the conductive base may be reduced. The characteristics such as resistance are adversely affected.

Therefore, in the case of the connector terminal, the thickness of the surface layer (Sn alloy layer) formed on the surface needs to be controlled quite accurately, and the alloy composition of the surface layer is also required. Similarly, it must be precisely controlled. This is a unique problem in a connector terminal different from the case of a lead wire having a Sn alloy layer on the surface, for example, in order to ensure only the solder wettability of the surface.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is directed to a reflow-processed Sn alloy plating material having excellent slidability, solderability, and corrosion resistance, and a fitting type using the same. The purpose is to provide connection terminals.

[0011]

In order to achieve the above object, in the present invention, a surface layer formed on the surface of a conductive substrate is coated with an electroplating layer of Sn or a Sn alloy and further coated thereon. A reflow-processed Sn alloy formed by subjecting an electroplated layer of at least one metal selected from the group consisting of Ag, Bi, Cu, In, and Zn to a reflow process. A plating material is provided.

Specifically, the concentration of the metal decreases in a gradient from the surface of the reflow treatment layer toward the conductive substrate, and the thickness of the Sn or Sn alloy electroplating layer is reduced. 0.3 to 2 μm, and the coating amount of the metal is 0.3 to 15% by mass with respect to the Sn amount in the Sn or Sn alloy electroplated layer, and the conductive substrate and the surface layer A base plating layer made of Cu or Cu alloy is interposed therebetween, and an intermediate layer made of Ni or Ni alloy is interposed between the base plating layer and the surface layer, In addition, a base plating made of Ni or a Ni alloy is interposed between the conductive substrate and the surface layer, and an intermediate plate made of Cu or a Cu alloy is provided between the base plating layer and the surface layer. Layers are interposed, The conductive substrate is made of Zn-containing C
A reflow-processed Sn alloy plating material comprising a u alloy is provided.

Further, in the present invention, in a fitting type connection terminal used by fitting a male terminal and a female terminal, at least a sliding portion of the male terminal and / or the female terminal may be any one of the above-described ones. And a reflow-processed Sn alloy plating material.

[0014]

FIG. 1 shows an example A of the material of the present invention. In this material A, a surface layer 2 described later is formed directly on the conductive substrate 1. This surface layer 2 is formed as follows. First, as shown in FIG. 2, Sn or Sn alloy (for example, Sn-
Ag, Sn-Bi, Sn-Cu, Sn-Pb, Sn-Z
n) and an electroplating layer 2A is formed.
On the above, an electroplating layer 2B made of at least one metal selected from the group consisting of Ag, Bi, Cu, In, and Zn is formed.

Next, a reflow process is performed on the whole. As a result, the two layers 2A and 2B are electrically plated layers 2B.
Is converted into one layer 2 made of an alloy of the above-mentioned metal and the Sn component in the electroplating layer 2A, that is, a Sn alloy layer (FIG. 1). Thus, the surface layer 2 is a reflow treatment layer,
As described above, Sn of the metal component and Sn component described above is used.
It is formed of an alloy. In this case, since the Sn alloy is an alloy with the above-described metal, the Sn alloy has higher hardness than the electroplated layer 2A before the reflow treatment.

Therefore, even when the surface layer 2 of the material A and the mating material are fitted and slid, the problem that the mating material bites into the surface layer 2 and scrapes hardly occurs, and the resistance between the two is reduced. The slidability is improved. In order to form the reflow treatment layer 2 exhibiting the above-described functions and effects, the coating amount of the electroplating layer 2B before the reflow treatment is 0.3 to 15% by mass with respect to the Sn component in the electroplating layer 2A. It is preferable to set so that

When the coating amount is less than 0.3% by mass, the hardness of the formed reflow treatment layer 2 is low, and the sliding resistance at the time of fitting sliding with the counterpart material is increased.
If the content is more than 5% by mass, it takes a long time to form the reflow treatment layer, and alloying with Sn is insufficient, causing problems such as that the surface does not become a Sn alloy.

Depending on the reflow treatment conditions selected, the concentration of the metal is high on the surface of the formed reflow treatment layer 2, and decreases gradually toward the conductive substrate 1. Can be changed.
When the reflow treatment layer 2 is formed in this manner, the sliding resistance is small on the surface and the flexibility of soft Sn is secured on the inside, so that it is possible to improve the contact characteristics, which is preferable. .

It is preferable that the thickness of the electroplated layer 2A formed before the reflow treatment is reduced to such an extent that its electric contact characteristics are not lost, from the viewpoint of reducing the sliding resistance. In addition, it is also preferable that the thinner layer facilitates formation of the reflow treatment layer. Usually, the thickness of the electroplating layer 2A is set to 0.3 to 2 μm. More preferably, it is set to 0.5 to 1.5 μm.

The conductive substrate 1 is usually made of Cu or a Cu alloy (for example, Cu-Zn, Cu-Sn, Cu-Ni-Si) in order to secure high conductivity and excellent mechanical strength.
Etc.) are used. In the case of connector terminals,
In many cases, a Cu alloy containing Zn is used as the conductive substrate. And depending on the application, this Zn may reach the outermost surface due to, for example, thermal diffusion during soldering,
In such a case, the contact characteristics deteriorate.

In order to prevent such a problem, before forming the electroplating layer 2A, the surface of the conductive substrate 1 is coated with C
u or Cu alloy (for example, Cu-Sn, Cu-Zn
) Or a Ni or Ni alloy (eg, N
i-P, Ni-Co, etc.) as a base plating layer.
Further, a Ni or Ni alloy layer and a Cu or Cu alloy layer thereon may be sequentially formed as an intermediate layer, or a Cu or Cu alloy layer and a Ni or Ni alloy may be formed thereon.
It is preferable that layers of the alloy are sequentially formed as an intermediate layer, and the whole of them functions as a barrier.

In the fitting type connection terminal of the present invention, when the male terminal and the female terminal are fitted and slid, at least one of the male terminal and the female terminal or both of the sliding portions is described above. It is composed of the following materials.

[0023]

EXAMPLES Examples 1 to 10 and Comparative Examples 1 to 3 Electroplating was performed on the surface of a Cu wire rod having a diameter of 0.8 mm to form an electroplating layer 2A and an electroplating layer 2B shown in Table 1. Then, each wire was subjected to a reflow treatment in a N ₂ gas furnace at a temperature of 350 ° C. for a time of 5 seconds, and both layers described above were converted into a reflow treatment layer 2 shown in FIG.

The friction coefficient and solder wettability of each of the obtained materials were measured according to the following specifications. (1) Friction coefficient: Using a Bowden-type friction measuring instrument, two wires are crossed in an X-shape, and the friction coefficient is determined under the conditions of a pressing load of 10 g, a sliding speed of 1 mm / sec, and a sliding distance of 10 mm. It was measured. Table 1 shows the results after one slide and the results after 10 slides.

(2) Solder wettability: Meniscograph method (Equipment: Solder Checker SAT-500 manufactured by Resca Co.)
0, flux: 25% rosin, methanol solution), first, the solder wetting time (second) was measured at room temperature, and then measured after heating in air at 170 ° C. for 24 hours. Table 1 summarizes the above results.

[0026]

[Table 1]

As is clear from Table 1, the material in which the alloy layer was not formed by the reflow treatment (Comparative Example 1) had a significantly reduced slidability as the sliding operation was repeated. Solder wettability is also significantly degraded. On the other hand, in Examples 1 to 10, the deterioration with time of the friction coefficient and the deterioration with time of the solder wettability are all small.

[0028]

As is apparent from the above description, the material of the present invention has a small resistance at the time of sliding sliding or has good solderability. Therefore, the fitting connection terminal manufactured from this material can be easily assembled even if the number of terminals is increased, and a highly reliable connection state can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a material A of the present invention.

FIG. 2 is a cross-sectional view showing a material A before a reflow process.

[Explanation of symbols]

Reference Signs List 1 conductive substrate 2 surface layer (reflow treatment layer) 2A electroplating layer (Sn or Sn alloy plating layer) 2B electroplating layer (Ag, Bi, Cu, In, Z)
n plating layer)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01R 4/02 H01R 4/02 Z // B23K 101: 38 B23K 101: 38 (72) Inventor Morimasa Tanimoto Tokyo 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Akira Matsuda 2-6-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Furukawa Electric Co., Ltd. 4K024 AA01 AA03 AA05 AA07 AA09 AA10 AA14 AA21 AB02 AB03 AB04 AB19 BA09 BB10 BC01 DB02 GA03 GA04 GA14 5E085 DD02 EE33 FF08 HH04 HH22 JJ26 JJ27

Claims (10)

[Claims] 1. A surface layer formed on a surface of a conductive substrate, wherein the surface layer is at least one selected from the group consisting of an electroplating layer of Sn or a Sn alloy and Ag, Bi, Cu, In, and Zn further covering the electroplating layer. A reflow-processed Sn alloy plating material, which is a reflow-processed layer formed by subjecting a metal electroplating layer to a reflow process. 2. The reflow-processed Sn alloy plating material according to claim 1, wherein the concentration of the metal decreases in a gradient from the surface of the reflow-processed layer toward the conductive substrate. 3. The reflow-treated Sn alloy plating material according to claim 1, wherein the thickness of the Sn or Sn alloy electroplating layer is 0.3 to 2 μm. 4. The method according to claim 1, wherein the coating amount of the metal is Sn or S.
0.3 to the amount of Sn in the electroplating layer of the n alloy
The reflow-processed Sn alloy plating material according to any one of claims 1 to 3, which is 15% by mass. 5. The method according to claim 1, wherein the conductive substrate and the surface layer are
The reflow-processed Sn alloy plating material according to any one of claims 1 to 4, wherein a base plating layer made of Cu or Cu alloy is interposed. 6. A method according to claim 1, wherein said surface layer and said base plating layer are
The reflow-processed Sn alloy plating material according to claim 5, wherein an intermediate layer made of Ni or a Ni alloy is interposed. 7. Between the conductive substrate and the surface layer,
The reflow-processed Sn alloy plating material according to any one of claims 1 to 4, wherein a base plating layer made of Ni or a Ni alloy is interposed. 8. A method according to claim 1, wherein said surface layer and said base plating layer are
8. The reflow-processed Sn alloy plating material according to claim 7, wherein an intermediate layer made of Cu or Cu alloy is interposed. 9. The reflow-processed Sn alloy plating material according to claim 5, wherein the conductive substrate is made of a Zn-containing Cu alloy. 10. A fitting connection terminal used by fitting a male terminal and a female terminal, wherein at least a sliding portion of the male terminal and / or the female terminal is provided.
Characterized in that the fitting connection terminal is formed of a reflow-processed Sn alloy plating material.