JPH0397841A - Soldered product for copper alloy - Google Patents

Abstract

PURPOSE:To obtain the soldered product for copper alloys in which the generation of Kirkendall voids is suppressed and the deterioration in the adhesion of solder caused by heat and its peeling phenomenon are improved by specifying the compsn. constituted of Zn, Sn and Pb with inevitable elements. CONSTITUTION:As the compsn. of a soldered product for copper alloys, the one contg., by weight, 0.03 to 5% Zn and the balance Sn and Pb with inevitable elements and in which >=98% Zn+Sn+Pb, <=2% total amounts of other elements and, furthermore according to necessary, <=0.4% Fe+Ni+Co+Si+P are regulated. In this way, the generation of Kirkendall voids is suppressed, and the deterioration in the adhesion of solder caused by heat and its peeling phenomenon can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to solder-plated copper alloys, especially copper alloys for electronic parts, and is particularly resistant to changes over time and heat.
This article relates to copper alloy solder-plated products that improve the reliability of plating connections. [Conventional technology] Conventionally, copper alloys used as electronic component materials are often plated with tin or solder at the raw stage, and the plating strength is 90% pure tin. l-10
Typical examples include % lead, 60% M-40% lead, etc. With the recent advances in electronic component materials, improving the reliability of components has become a major issue, such as connectors and integrated circuits (
rc), the plating parts deteriorate due to the use environment or the heat generation of the electronic components themselves.
Depending on the conditions of use, this may lead to a decrease in reliability.
There have also been cases where the plating has peeled off.

Figure 1 is a cross-sectional view of a copper alloy model immediately after conventional solder plating, and Figure 2 is a cross-sectional view of the model after heating. In the figure, (I) is a copper alloy, and (2) is a copper alloy. (1) the solder plating layer plated on top, (3) the tin constituting the solder plating layer (2), (4) the button, and (5) the diffusion layer (η
Phase) ． (6) is diffusion M (ε phase). (7) is a Kirkendall void. Immediately after applying solder plating to the copper alloy, a solder plating layer (2) as shown in Fig. 1 is obtained, but after that, due to heating and changes over time, a diffusion state as shown in Fig. 2 occurs, resulting in peeling. ! Kirkendall void (7), which is the cause of the phenomenon, occurs.

The Kendall void (7) is a phenomenon in which voids are formed due to the difference in diffusion speed due to the movement of atoms when the copper alloy (1) and the solder plating layer (2) progress through mutual diffusion. The diffusion layer generally has a Cu phase (5) (Cu, Sn,) and an ε phase (6) (Cu, Sn) as shown in Figure 2.
However, the situation may differ depending on the composition of the copper alloy (1) to be plated, and therefore the reliability after plating will also differ.

[Problem to be solved by the invention]

In conventional solder-plated products for copper alloys, diffusion occurs as described above, so preventing Kirkendall voids from occurring during diffusion is an important issue for improving component reliability.

This invention was made to solve the above-mentioned problems by adding zinc to the conventional solder plating composition to suppress the occurrence of Kirkendall voids, thereby reducing the adhesion of solder plating caused by heat. The object of the present invention is to obtain a solder-plated copper alloy product that can improve the peeling phenomenon.

[Means to solve the problem]

This invention relates to the following solder plated product for copper alloys.

(1) Zinc 0.03 to 5 on a weight basis as a plating composition
%, with the remainder consisting of tin, lead and unavoidable elements,
Solder plated products for wire mesh alloys in which the total amount of zinc, tin, and lead is 98% or more, and the total amount of other elements is 2% or less.
...Solder plated products (1) (2) The plating composition contains 0.03 to 5% zinc on a weight basis, and the balance consists of tin, lead, and other elements. The total amount is 98% or more, the total amount of other elements is 2% or less, and Fe
．． Ni. A solder plated product for copper alloy in which the total amount of Go, Si and P is 0.4% or less.・・・
...Solder plated product (II) In the present invention, the ratio of tin and lead as a plating composition can be set to any desired ratio. Other elements include Fe. Ni. Go
, S.L. Examples include P and other arbitrary elements.

[For production]

The purpose of adding zinc in the solder plated products (1) and (II) of this invention is to suppress the generation of Kirkendall voids due to the movement of zinc element during diffusion, and this effect is observed at a minimum amount of 0.03%. This becomes more noticeable as the amount added increases. On the other hand, increasing the amount of zinc added tends to reduce solderability during component mounting, so the upper limit was set at 5%. The reason why the total amount of other elements was set to 2% or less is because solderability similarly decreases. Fe in solder plated products (■). Ni. Co. Si,
The upper limit of the total amount of P is determined as an amount that does not have any adverse effects, since the addition of these elements tends to increase the occurrence of Kirkendall voids, and the maximum value of each element is is preferably 0.2% each.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

Commercially available phosphor blue for springs (JIS C5210), Table 1
Solder having the composition was plated by direct electroplating to a plating thickness of 2 μm. After that, a heating test was conducted at 150℃, and the time until peeling occurred was measured by a bending test. After electrolytic solder plating, molten solder plating was performed at 240℃, and the time until the solder plating layer became wet was measured. . The time it takes for the solder plating layer to get wet is the time it takes for the tension to balance out the floating force caused by the surface tension that occurs when phosphor bronze electroplated with solder is immersed in molten 6o%Sn-40%PB. did. Show the results to the table worker.

From the results in Table 1, the solder-plated products of the present invention with zinc added have a significant improvement effect on heat-resistant peeling. From the results of samples Nα1 to Nα5, it was found that the higher the amount of zinc added, the better the heat peeling resistance was, but on the contrary, the solderability decreased, which served as the basis for setting the amount of addition to 0.03 to 5%. ing. Also, from the results of samples Nα8 to 1l. Fe, Ni,
Go. Si. It has been found that P and the like cancel out the improvement in heat peeling resistance due to the addition of zinc, and based on these results, the upper limit of each is set at 0.2%. In the above embodiment, due to the diffusion phenomenon of solder and copper, the solder-plated product is intended for copper alloys, but it is thought that there will be no particular problem if it is applied to materials other than copper alloys.

In addition, with the aim of improving solderability and adhesion,
Of course, it is also possible to use it by reheating and reflowing it after electroplating. [Effects of the Invention] According to the present invention, since dumbbell is added to the solder plating composition, the occurrence of Kirkendall voids can be suppressed,
This can prevent the solder plating from deteriorating in adhesion and peeling due to heat.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a copper alloy model immediately after conventional solder plating, and FIG. 2 is a sectional view of the model after heating. In each figure, the same reference numerals indicate the same or corresponding parts, (1)
is a copper alloy, (2) is a solder plating layer, and (5) is a diffusion layer (
η phase). (6) is a diffusion layer (ε phase). (7) is Kirkendall void.

Claims (2)

[Claims] (1) Plating composition: Zinc 0.03 to 0.03 on a weight basis
For copper alloys containing 5% and the remainder consisting of tin, lead and unavoidable elements, the total amount of zinc, tin and lead being 98% or more and the total amount of other elements being 2% or less Solder plated product. (2) Zinc 0.03~ on a weight basis as a plating composition
5%, the balance consists of tin, lead and other elements, the total amount of zinc, tin and lead is 98% or more, the total amount of other elements is 2% or less, and Fe, Ni, Co, Si and A solder plated product for copper alloy, characterized in that the total amount of P is 0.4% or less.