JPH03153857A - Tinned copper alloy bar - Google Patents

Abstract

PURPOSE:To produce a tinned copper alloy stock remarkably excellent in the heat resistance adhesive strength of tinning by subjecting a copper alloy containing specific percentages of Sn and P to galvanizing of specific thickness as undercoat plating and then to tinning. CONSTITUTION:At the time of applying undercoat plating and tinning to a copper alloy having a composition consisting of, by weight, 0.5-10% S, 0.01-0.35% P, and the balance Cu with inevitable impurities, galvanizing of 0.05-2mu thickness is performed as undercoat plating. By this method, the tinned copper alloy stock remarkably excellent in the heat resistance adhesive strength of tinning can be obtained. This stock is useful, e.g. as a copper alloy bar for electronic equipment, such as terminal and connector.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Sn-plated copper alloy material used for copper alloy strips for electronic devices such as terminals and connectors.

[Conventional technology]

BACKGROUND ART Conventionally, for example, Sn-plated copper alloy strips for electronic devices have been frequently used, in which a copper alloy such as a brass-based alloy or a phosphor bronze-based copper alloy is used as a base material and Sn-plated thereon. Regarding the base plating, there are cases where no base plating is applied, cases where Cu plating is applied, or Ni
There are cases where plating is applied, and each is put into practical use under conditions such as changing the thickness of the base plating.

Against this background, in fields where relatively high reliability is required, Sn-plated bronze alloy materials are the mainstream, and there are various types depending on the required level of Sn plating adhesion reliability. Base plating is used under these conditions.

In recent years, with the shift to smaller size and higher output of electronic devices, the environment in which components for electronic devices are used has become even more severe. For example, in connectors, etc., there is a rise in temperature due to heat generation, etc., and if they are used for a long period of time in such a usage environment, the adhesion of the Sn plating to the base material may decrease, leading to peeling of the Sn plating. be. Therefore, even higher reliability is required for electronic equipment components compatible with recent high-output equipment.

As a method for manufacturing a highly reliable contact made of phosphor bronze plated with Sn, for example, the concentration of monovalent Cu ions is 10 to 60 g/Q, and the concentration of free cyanide is 10 to 20 g.
Either apply a thin Cu underplating to the phosphor bronze base material using IQ's cyanizing bath, then electroplate Sn or Sn alloy as the overlying plating, and then heat-melt it.
Alternatively, a method of hot-dipping Sn or Sn alloy as top plating has been proposed (Japanese Patent Laid-Open No. 59-1844).
No. 82).

Regarding the adhesion of the Sn plating on the copper alloy, due to mutual diffusion between the Cu in the copper alloy and the Sn in the plating, a weak diffusion layer of Cu and 8 holes is formed near the interface between the copper alloy and the Sn plating. It is known that the adhesion of Sn plating is reduced due to the occurrence of Kirkendahl voids.

[Problem to be solved by the invention] Regarding the influence of the base plating on the heat-resistant adhesion of Sn plating, the Nx base plating has the highest reliability, while the Cu base plating has the highest reliability.
At present, base plating and no base plating are relatively unreliable in terms of long-term heat-resistant adhesion. However, Ni plating has the advantage of being relatively hard, and products with Ni underplating have the major drawback of being prone to cracking during forming processes such as press working, making them difficult to use industrially. .

The present invention is aimed at improving the conventional problems, and includes:
It is an object of the present invention to provide a Sn-plated steel alloy material with extremely excellent heat-resistant adhesion of n-plating.

[Means to solve the problem]

The 8-hole plated copper alloy material of the present invention has Sn 0.5 at 1% by weight.
~10% and P 0.01~0.35%, with the remainder consisting of Cu and unavoidable impurities, in a Sn-plated steel alloy material that has been subjected to base plating and Sn plating. 0.05-21m Zn
It is plated.

In the present invention, as the base plating, the thickness is 0.05 to 2-
It is also possible to apply the Zn base plating alone.

0. It is also possible to perform base plating with a two-phase or three-phase configuration in combination with the Cu base plating of OS~5-.

Examples of such Sn-plated copper alloy materials include the following.

(1) Zn with a thickness of 0.05 to 27a as the base plating
Sn-plated steel alloy material.

(2) Sn-plated steel alloy material, which has been subjected to Zn plating with a thickness of 0.05 to 24 mm as base plating, and then Cu plating with a thickness of 0.05 to 5 II m.

(3) Sn-plated copper alloy material, which is coated with Cu plating with a thickness of 0.05 to 54 mm and then Zn plating with a thickness of 0.05 to 2 mm as base plating.

(4) As base plating, Cu plating with a thickness of 0.05 to 5 JIIa is applied, and then Cu plating with a thickness of 0.05 to 5 JIIa is applied. OS~2Ia Zn
A Sn-plated steel alloy material that has been plated and further plated with Cu to a thickness of 0.05 to 51a.

[For production]

In the Sn-plated copper alloy material of the present invention, copper alloy and Sn
In the process of a series of diffusion phenomena between Cu and 8 at the plating interface, the movement of Zn in the base plating suppresses the occurrence of Kirkendall voids, and as a result, the adhesion of the Sn plating is improved.

The effect of Zn underplating is recognized at a Zn plating thickness of 0.05°, and the effect becomes more pronounced as the plating thickness increases. However, when the thickness of the Zn base plating exceeds 2 tones, a decrease in solder wettability after plating is observed.

When using a two-phase or three-phase composite base plating consisting of Zn plating and Cu plating, the Cu plating is Zn.
The purpose is to improve the plating adhesion between the plating and the base material, or between the Zn plating and the Sn plating, and to suppress the progress of the diffusion phenomenon between the base material and the Sn plating, and the thickness of each plating can be used industrially. This is considered to be the range in which the desired effect can be obtained.

[Embodiments of the invention]

Commercially available JIS C5111 or C5210 as base material
Using a strip material made of copper alloy with a thickness of 0.25 mm, various base platings as shown in Table 1 were applied using an industrial-scale electroplating device, and then Sn plating was applied to a Sn plating thickness of 2.5 mm. An 8-hole plated copper alloy strip was prepared.

Plating adhesion was evaluated by conducting an accelerated test by heating in a constant temperature bath at a temperature of 100° C. using a rectangular specimen with a width of 20+ m+ and a length of 80 m, and evaluating the change in adhesion decrease over time. In addition, to check for adhesion deterioration, an adhesion bending test was conducted on specimens that had been heated for a predetermined period of time.

Further, the sample was bent back to its original state, and the bent portion was observed using a stereomicroscope (20x magnification), and judgment was made based on the presence or absence of peeling of the Sn plating.

In addition, the solder wettability and moldability of each specimen immediately after plating were comparatively evaluated.

Table 1 shows a comparison of various properties of Examples and Comparative Examples.

From the results in Table 1, Examples 1 to 1 with Zn underplating
No. 12 and Comparative Examples 4 and 8 show significant improvement in the heat-resistant adhesion of plating compared to Comparative Example 1.2°5.6.

On the other hand, although Comparative Examples 4 and 8 are as good as the examples in terms of heat-resistant adhesion of plating, a decrease in solder wettability immediately after Sn plating is observed, so they are not perfect for industrial use. It's hard to say.

Furthermore, Comparative Example 3.7 has the same excellent plating heat-resistant adhesion and solder wettability as the Examples.

It has poor moldability and is unsuitable for industrial use.

In addition, in the above embodiment, S of the phosphor bronze alloy at the raw stage
Although the present invention is intended for n-plated products, the present invention also applies when phosphor bronze that has not been subjected to Sn plating is molded into a member for electronic equipment by pressing or etching, and then Sn plating is applied for practical use. By applying base plating.

Naturally, effects similar to those of the present invention can be expected. Furthermore, it is naturally possible to perform reheating and reflow treatment after Sn plating for the purpose of improving solder wettability, plating adhesion, and the like.

〔Effect of the invention〕

As described above, in the present invention, the steel alloy is coated with a thickness of 0.05 to 2II as a base plating or as a part of the base plating.
Since Sn plating was applied after Zn plating of Ia, a Sn-plated copper alloy material with extremely excellent heat-resistant adhesion of Sn plating was obtained.

Claims (1)

[Claims] (1) Sn0.5~10% and P0.01~ in weight%
In the Sn-plated copper alloy material, which is made by applying base plating and Sn plating to a copper alloy containing 0.35% Cu and unavoidable impurities, Zn plating with a thickness of 0.05 to 2 μm is applied as the base plating. A Sn-plated copper alloy strip.