JPH07150272A - Tin plated copper alloy material for electrical and electronic parts and production thereof - Google Patents

Abstract

PURPOSE:To produce a tin plated copper alloy material for electrical and electronic parts excellent in solderability even if a tin plating layer therein is thin and furthermore excellent in thermal peeling resistance and to provide a method for producing the same. CONSTITUTION:This material is the one in which the middle of a copper alloy and a tin plating layer is provided with an intermetallic compound layer of iron and tin formed by melting having 0.1 to 0.4mum thickness. The surface of the copper alloy is applied with an iron or iron alloy plating layer of 0.08 to 0.3mum, and the surface is furthermore applied with tin plating and the tin plating layer is thereafter reflowed, by which the middle of the copper alloy material and tin plating layer is provided with the intermetallic compound layer of iron and tin having 0.1 to 0.4mum thickness. Moreover, the surface of the copper alloy is applied with the iron or iron alloy plating layer of 0.08 to 0.3mum, which is thereafter immersed in molten tin and is applied with tin plating, and at the same time, the middle of the copper alloy material and tin plating layer is provided with the intermetallic compound layer of iron and tin having 0.1 to 0.4mum thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin-plated copper alloy material for electric / electronic parts and a method for producing the same.

[0002]

2. Description of the Related Art Tin-plated copper alloy materials are used in various electric and electronic parts such as terminals and connectors. The purpose of applying tin plating for electric / electronic parts is to impart corrosion resistance and good solderability. Also, at the contact,
It also has the purpose of keeping the contact resistance low and stable.

Conventionally, most of these tin-plated copper alloy materials have been manufactured by directly plating the copper alloy with tin, or by plating copper undercoat between the copper alloy material and the tin-plated material.

Electricity using these tin-plated copper alloy materials
Electronic components are affected by heat during soldering during mounting and in the usage environment after mounting. This thermal effect causes various problems as described below by oxidizing the surface of the tin plating layer or promoting diffusion of Cu in the copper alloy or copper undercoat into the tin plating.

For example, tin plating and Cu from the copper alloy or the copper undercoat plating react and diffuse to form a brittle intermetallic compound, and when the thickness increases, the plating layer peels off during bending. Cause of. Further, if the entire tin-plated layer is alloyed and the pure tin layer is lost, soldering becomes impossible.

As one of the measures for avoiding these problems, there is a method in which a tin plating layer is thickly formed (for example, 3 to 5 μm) to increase the diffusion time of Cu to the surface of the tin plating layer, but tin is expensive. Since it is a simple metal, there is a problem that the cost of the tin-plated material is increased. Further, if the tin plating is thick, a large amount of tin burrs (stamping residue) is generated on the end surface during stamping, which causes a problem of shortening the life of the mold.

Therefore, a tin-plated copper alloy material having a conventional thin tin-plated layer (usually 1 to 1.5 μm) and excellent in heat-resistant peeling property and heat-resistant soldering property is desired.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a tin-plated copper alloy material for electric / electronic parts which is excellent in solderability and heat-resistant peeling property even when the thickness of the tin-plated layer is thin, and a method for producing the same. The purpose is to provide.

[0009]

A tin-plated copper alloy material for electric / electronic parts for solving the above-mentioned problems is an iron produced by melting 0.1 to 0.4 μm between a copper alloy and a tin-plated layer. And an intermetallic compound layer of tin and tin.

A method of manufacturing a tin-plated copper alloy material for electric / electronic parts for solving the above-mentioned problems is a method of forming a tin alloy on a surface of a copper alloy.
An iron or iron alloy plating layer having a thickness of 08 to 0.3 μm is applied, and then tin plating is applied on the iron or iron alloy plating layer, and then the tin plating layer is re-melted (reflowed) so that the copper alloy material and the tin plating layer are provided with 0 An intermetallic compound layer of iron and tin having a thickness of 1 to 0.4 μm is provided.

Further, the method for producing a tin-plated copper alloy material for electric / electronic parts is as follows. The surface of the copper alloy is coated with an iron or iron alloy plating layer having a thickness of 0.08-0.3 μm It is characterized in that an intermetallic compound layer of iron and tin having a thickness of 0.1 to 0.4 μm is provided between the copper alloy material and the tin plating layer at the same time as immersing in and tin plating.

[0012]

The operation of the present invention will be described below together with the findings obtained in the present invention. When tin plating is applied on a copper alloy or copper undercoat, tin and copper react and diffuse to form Cu.
_An ε layer made of ₃ Sn and an η layer made of Cu ₆ Sn ₅ are formed. These diffusions are very fast, and the diffusion is 1-2 μm at 100 to 200 ° C. for several hours to several tens of hours. However, the inventor of the present invention is to provide an intermetallic compound layer of iron and tin having an appropriate thickness between the copper alloy and the tin plating layer, because the intermetallic compound layer of iron and tin is It has been found that it prevents the diffusion of copper and thus the formation of intermetallic compounds in the tin plating layer. Therefore, the tin-plated layer can stably store the pure tin portion. Here, the intermetallic compound of iron and tin means Fe ₃ Sn, Fe ₃ Sn ₂ , FeSn, FeSn ₃
That is.

Conventionally, when an intermetallic compound such as an intermetallic compound of copper and tin or an intermetallic compound of iron and tin is formed, the plating layer is formed from the interface between the layer of the intermetallic compound and the copper alloy material by bending. Was said to peel off.

However, the present inventor has found that, unlike the intermetallic compound formed by diffusion over time, the one formed by melting has excellent adhesion without defects due to diffusion at the interface. However, when the present inventor repeatedly conducted many experiments on the intermetallic compound formed by melting, it was found that the intermetallic compound was also exfoliated by bending. Then, when the peeling was performed in detail and in what case the peeling was not performed, it was found that the presence or absence of the peeling was greatly influenced by the thickness of the intermetallic compound. That is,
As will be described in detail later, it was found that when the intermetallic compound layer is thinner than a certain thickness, no peeling of the plating occurs.

As described above, by forming an intermetallic compound layer of iron and tin, which has been hitherto adversely affected, at a temperature higher than the melting point of tin, and controlling the thickness appropriately, On the contrary, it was clarified that the mutual diffusion of Cu and Sn is suppressed and the alloying of the tin plating layer is prevented. It was also found that such an intermetallic compound of iron and tin has a far higher effect of suppressing diffusion of Cu in a copper alloy than an intermetallic compound of Ni ₃ Sn. Thus, the inventors have invented a tin-plated copper alloy material having stable solderability both thermally and with time, and a method for producing the same.

Here, the thickness of the intermetallic compound layer of iron and tin is set to 0.1 μm or more in order to prevent diffusion of copper into tin. This is because the compound layer is necessary. The reason why the thickness is 0.4 μm or less is that there is no great difference in the effect of preventing the diffusion of copper even if the thickness is thicker than that. Further, when the intermetallic compound layer of iron and tin grows to 0.4 μm or more, bending stress increases during bending, and the intermetallic compound layer of iron and tin peels off from the interface of the copper alloy.
This is because most of the tin-plated layer becomes an alloy layer and solder cannot adhere to it. Further, if the alloy layer is thicker than necessary, it may shorten the life of the die when stamping the tin-plated material. Therefore, the thickness of the intermetallic compound layer of iron and tin is set to 0.1 to 0.4 μm.

Next, the manufacturing method will be described. The method of applying tin plating may be either a method of performing a reflow treatment after electroplating or a method of immersing it in molten tin. In the former, when the electroplating film is redissolved, the plating and the tin plating melt to form an intermetallic compound layer of iron and tin.
Also, in the case of hot dip iron plating, an intermetallic compound layer of iron and tin is similarly formed. In all of these, the step of applying tin plating and the step of changing iron plating into an intermetallic compound layer are performed.

The thickness of the iron plating is set to 0.08 μm or more because if it is thinner than this, the thickness of the intermetallic compound layer of iron and tin is insufficient and the effect of preventing Cu from diffusing into the Sn plating is achieved. Because it will be insufficient. The reason why the thickness is 0.3 μm or less is that if it is thicker than that, an intermetallic compound layer of iron and tin having an unnecessary thickness is formed and workability is deteriorated. Therefore, the thickness of iron plating is set to 0.05 to 0.3 μm.

It is important that the iron plating is completely gone after the reflow treatment and the hot tin plating. This is because if the iron plating layer remains, the interdiffusion of iron and tin will proceed while the material is used as an electronic component.
This is because the intermetallic compound layer composed of iron and tin may grow further and become thicker than necessary. The intermetallic compound formed by diffusion may cause peeling due to defects in the interface of the plating layer. In addition, an intermetallic compound layer having an excessive thickness reduces workability.

The thickness of the tin plating is preferably thin in consideration of cost and generation of scraps during stamping. On the other hand, from the viewpoint of heat-resistant peelability and solderability, a thicker one is desirable. However, assuming that the period from plating to processing into parts and soldering when mounted on equipment is about 1 year, in order to maintain solderability during that period, at least 0.8 μm Think necessary. The details may be determined according to the application of the plated material. Of course, 0.8μ if the period before soldering is short
It may be thinner than m, and even in that case, peeling does not occur.

The copper alloy material to be plated is preferably an alloy containing tin and iron. This is because many terminals, connectors and other contacts are made by stamping, but if the copper alloy contains iron, the stamping debris can be reused without peeling the plating layer. is there.

In particular, the copper alloy is Sn: 1.5-2.
5% by weight, Fe: 0.05 to 0.15% by weight, P: 0.
02-0.05 wt%, copper alloy consisting of the balance Cu, or Zn: 1.0-5.0 wt%, Sn: 1.0-2.5
% By weight, Fe: 0.05 to 0.15% by weight, P: 0.0
It is preferable to use a copper alloy composed of 2 to 0.05% by weight and the balance Cu. These alloys are copper alloys excellent in heat resistance without change in material properties such as strength and conductivity even when the manufacturing method of the present invention is used. Further, even if Cu undercoating is not applied, metal of iron and tin is used. Zn can be prevented from diffusing only by the intermetallic compound layer, and good solderability and contact resistance value can be maintained over time.

[0023]

Example A tin-plated material shown in Table 1 was prepared. As the phosphor bronze material, a phosphor bronze type 2 material composed of Cu6 wt% Sn-0.045 wt% P was used. Also, KLF-5 is Cu-
It is a copper alloy composed of 2 wt% Sn-0.1 wt% Fe 0.03 wt% P. The tin plating solution composition and plating conditions used are shown in Table 2. The composition of the iron alloy plating solution and the plating conditions are shown in Table 3. At this time, the composition of the iron alloy plating layer was 90% by weight of iron.

100% of these tin-plated materials at 150 ° C.
After heat treatment for 500 to 1000 hours, 9 of these materials
Bending was repeated twice at 0 °, and the surface of the bent portion was observed with a stereoscopic microscope to confirm the presence or absence of peeling of the plating layer. Also, solderability is 1 at 220 ° C considering the reflow soldering method that has been increasing with the recent surface mounting of connectors.
Evaluation was performed after heat treatment for a range of up to 0 minutes. Solderability is
After soldering, a solder adhesion area of 85% or more was defined as “good”, and a solder adhesion area of less than 85% was defined as “defective”. The results are shown in Table 1.

As a result, thermal peeling did not occur when the thickness of the intermetallic compound layer of iron and tin was 0.1 μm or more. This is because the intermetallic compound of tin and iron suppresses the diffusion of copper into the tin layer, so that the intermetallic compound of tin and copper hardly grows, and Kirkendall voids that are said to cause thermal exfoliation do not occur. Is. Further, with the conventional material, peeling of the plating occurred at 150 ° C. for 500 hours. When the thickness of the intermetallic compound layer of iron and tin was 0.5 μm or more, peeling occurred in the bending test. Therefore, the thickness of the intermetallic compound layer of iron and tin is 0.1
0.4 μm is suitable.

[0026] In addition, the one without iron plating is 220
In contrast to soldering failure caused by heat treatment at ℃ × 5 minutes,
The tin-plated product according to the present invention provided good solderability even after 10 minutes. The example material of the present invention was also excellent in terms of the thermal effect on the solderability.

[0027]

According to the present invention, it is possible to provide a tin-plated copper alloy material for electric and electronic parts, which is excellent in heat-resistant peeling property and heat-resistant soldering property. This tin-plated copper alloy material improves heat-resistant peeling resistance and heat-resisting solderability of electric and electronic parts such as terminals and connectors, and can contribute to increase the reliability of equipment.

[Brief description of drawings]

FIG. 1 is a table showing test conditions and results in Examples.

FIG. 2 is a table showing tin plating conditions and the like in examples.

FIG. 3 is a table showing iron plating conditions and the like in examples.

Claims (7)

[Claims] 1. 0.1 to 0.1 is provided between the copper alloy and the tin plating layer.
A tin-plated copper alloy material for electric and electronic parts, which has an intermetallic compound layer of iron and tin produced by melting in a thickness of 0.4 μm. 2. The tin-plated copper alloy material for electric / electronic parts according to claim 1, wherein the copper alloy is a copper alloy containing iron and tin as components. 3. The copper alloy comprises Sn: 1.5 to 2.5% by weight, Fe: 0.05 to 0.15% by weight, P: 0.02.
~ 0.05 wt%, copper alloy with balance Cu, or Z
n: 1.0 to 5.0 wt%, Sn: 1.0 to 2.5 wt%, Fe: 0.05 to 0.15 wt%, P: 0.02
The tin-plated copper alloy material for electric / electronic parts according to claim 2, which is a copper alloy consisting of 0.05% by weight and the balance Cu. 4. An iron or iron alloy plating layer having a thickness of 0.08 to 0.3 μm is formed on the surface of a copper alloy, tin is further plated thereon, and then the tin plating layer is re-melted (reflow). , 0.1 between copper alloy material and tin plating layer
A method for producing a tin-plated copper alloy material for electric / electronic parts, which comprises providing an intermetallic compound layer of 0.4 μm of iron and tin. 5. An iron or iron alloy plating layer having a thickness of 0.08 to 0.3 μm is applied to the surface of a copper alloy, which is then immersed in molten tin and tin-plated, and at the same time, a copper alloy material and a tin-plated material. A method for producing a tin-plated copper alloy material for electric / electronic parts, which comprises providing an intermetallic compound layer of iron and tin having a thickness of 0.1 to 0.4 μm in the middle of the layers. 6. The method for producing a tin-plated copper alloy material for electric / electronic parts according to claim 4, wherein a copper alloy containing iron and tin as components is used as the copper alloy. 7. The copper alloy comprises Sn: 1.5 to 2.5% by weight, Fe: 0.05 to 0.15% by weight, P: 0.02.
~ 0.05 wt%, copper alloy with balance Cu, or Z
n: 1.0 to 5.0 wt%, Sn: 1.0 to 2.5 wt%, Fe: 0.05 to 0.15 wt%, P: 0.02
7. The method for producing a tin-plated copper alloy material for electric / electronic parts according to claim 6, which is a copper alloy composed of 0.05% by weight and the balance Cu.