JPH11350188A - Material for electric and electronic parts, its production, and electric and electronic parts lising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material suitable for electric and electronic parts, especially, lead material or contact material, which is excellent in resistance to heat and surface oxidation-discoloration and which exhibits little deterioration in the jointing strength at the jointing part when it is jointed with a solder, and to provide the method for producing the electric and electronic parts using the material. SOLUTION: This material is constituted of a substrate 1 wherein at least surface layer consists of Cu or Cu alloy, an intermediate layer 2 which is formed on the substrate and has at least one layer selected from Cu-layer, Ni-layer Ni alloy-layer or Ag-layer, and a surface layer 3 which is formed on the intermediate layer 2 and consists of a Sn- or Sn alloy-layer having Cu-content of 0.1-3 wt.% and a thickness of 0.5-20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for an electric / electronic component and a method for producing the same, and an electric / electronic component using the material, and more particularly to a lead material for various semiconductor devices, a terminal, a connector, The present invention relates to a material suitable for use as a contact material for a switch, a method for manufacturing the same, and an electric / electronic component using the material.

[0002]

2. Description of the Related Art Conventionally, Cu or Cu alloy has been widely used as a material of components incorporated in various electric and electronic devices. That is, the application is typically lead materials such as lead wires and lead pins of individual semiconductors and IC packages, or lead frames, and also extends to contact materials such as sockets, connectors, switch terminals, and contact springs. . These applications are based on the fact that Cu or Cu alloy has excellent electrical and thermal conductivity, mechanical strength and workability, and is economically advantageous. is there.

In particular, Cu alloys of various alloy designs have been developed for lead materials of IC packages.
They are also being applied in the field of contact materials such as terminals and contact springs.

[0004] As the lead material described above, conventionally,
Fe-based materials such as Kovar alloys, Fe-Ni-based alloys represented by 42 alloys, and Fe-C-based alloys are also used. This Fe-based material, compared to the above-mentioned Cu alloy,
Thermal conductivity and conductivity are inferior, but mechanical strength is high,
In addition, since the coefficient of thermal expansion is similar to that of the sealing resin for Si chips and packages, the surface of the diode or capacitor is plated with Cu several tens of μm thick to improve conductivity and solder wettability. It is used as a lead wire.

Conventionally, Cu-based materials have had a problem in mechanical strength, but recently Cu alloys having improved strength characteristics have been developed. For example, a precipitation-strengthened Cu alloy in which a small amount of Ni and Si are contained and then precipitated in a form such as Ni ₂ Si is known. Since this Cu alloy has excellent stamping properties and stress relaxation properties, it has begun to be used as a lead material, a contact material for terminals and connectors.

[0006] In the case of the above-mentioned component materials, the surface thereof is subjected to a surface treatment represented by plating to enhance the reliability of the material functions and is actually used.

For example, in the case of a lead material used for mounting components on a printed circuit board by soldering, a measure is taken to improve the solderability by applying Sn plating or Sn alloy plating on the surface. Specifically, after assembling the IC package, the outer lead portion of the lead frame is subjected to exterior solder plating using, for example, an Sn-Pb alloy, or the lead wires of individual semiconductors and capacitors are previously subjected to Sn plating or Sn-Pb alloy. In some cases, plating is performed, and reheating is performed by heating.

Further, when the substrate is made of Cu or Cu alloy, if the surface is plated with Sn or Sn alloy, the obtained material has corrosion resistance,
Since they have excellent wear resistance and are economically advantageous, they are widely used as materials for various terminals and connectors in addition to lead materials. In applications where surface gloss is required, those plated with bright plating of Sn or Sn alloy or those subjected to reflow treatment are used. In particular, those subjected to reflow treatment have whisker resistance. Because of its excellent heat resistance and heat resistance, it has begun to be used as a material for components used in harsh temperature environments.

For example, in the field of automobiles in which electric components have been widely mounted, contact materials such as terminals and connectors to be incorporated are in a high temperature range of about 100 to 170 ° C., including in an engine room. You will be exposed to the environment. Conventionally, in such a field, a material obtained by subjecting the surface of a substrate made of brass or phosphor bronze to Sn alloy plating such as Sn plating or solder has been mainly used, but must always be satisfied in a severe use environment. Because it is not the performance, the material which has been subjected to reflow treatment after Sn plating is applied to the above-described Cu alloy containing Ni and Si for the purpose of improving the strength characteristics and the stress relaxation characteristics has begun to be used.

On the surface of Cu or Cu alloy, S
In the case of an n-plated material, there are the following problems.

First, Sn whiskers are liable to occur in the formed Sn plating layer, which may cause a short circuit accident when components are mounted.
Further, since the melting point of Sn is 232 ° C., for example, when soldering and mounting the material component on a printed circuit board,
The substrate material (resin) needs to have higher heat resistance, and at the same time, Sn itself is oxidized at that time, so that the solderability tends to deteriorate.

In the case of a contact material, unlike the case of, for example, an outer solder film of an outer lead portion of a lead frame, Sn or Sn which is a surface layer is usually used.
Since the thickness of the alloy layer is as thin as 1 to 1.5 μm, the Cu component on the substrate surface is thermally diffused to the surface layer at an early stage in the high temperature environment as described above, and as a result, the surface layer of the surface layer is Discoloration and oxidation occur, resulting in a problem that the contact resistance with the partner material increases.

Further, in the case of a lead wire for a capacitor, the thickness of the plating layer is increased in order to build up a welded portion with, for example, an aluminum wire to be welded. When the treatment is performed, there is a problem that the uneven thickness of the Sn plating layer formed by solidification after the treatment is increased.

The above problem of whiskers can be substantially prevented by performing a reflow process.
If an Sn alloy is used as the material of the plating layer, it can be suppressed considerably. A typical example of such a Sn alloy is solder (Sn-Pb alloy), which has been widely used in the past.

However, the Pb contained in the solder
In the future, it is expected that its use will be shunned in spite of its excellent properties because it may adversely affect the human body. And, S which does not contain Pb
n alloy, specifically, Sn-Ag based, Sn-Bi based, S
The transition to the n-In type and Sn-Zn type is under study.

However, the materials in which the plating layers are formed of these Sn alloys have the following problems.

First, the melting point of these alloys is relatively low or high as compared with the Sn-Pb eutectic solder, or, for example, the heat of a heating step at the time of assembling an IC package is as follows. There is a problem that Cu or the like, which is a constituent material of the substrate surface, is thermally diffused into the surface portion of the Sn alloy plating layer, and the solderability of the Sn alloy plating layer is deteriorated.

Furthermore, for example, in the case of the above-described capacitor lead, when welding with an aluminum wire, the temperature of the welded portion is instantaneously at around 2000 ° C., so the Sn alloy plating is performed near the welded portion. Elements such as Zn, Bi, and In in the layer are instantaneously vaporized, and as a result, a blowhole is generated in the welded portion, which causes a problem that the welding strength is reduced. In addition, in the welded portion, Cu and the like are thermally diffused from the surface of the base to form a Cu-Sn-based compound layer on the surface of the lead material, so that discoloration of the surface and deterioration of solderability may occur.

Among the above-mentioned alloys exemplified as Sn alloys containing no Pb, Sn-Ag and Sn-In alloys have the problem that they are expensive in addition to the above-mentioned problems.

The Sn-Bi alloy is inferior in heat resistance, easily causes thermal diffusion of Bi to the substrate surface, and is inferior in bending workability, so that cracks are easily generated in the plating layer. There is a problem that the joining strength of the joint formed after soldering decreases with time. In addition, the Sn—Zn-based alloy is liable to cause surface oxidation and has poor solder wettability in the air.
Since n tends to cause thermal diffusion, the bonding strength of the bonding portion after soldering also decreases with time, as in the case of the Sn-Bi-based one. Thus, the Pb-free Sn alloy also has many problems.

[0021]

However, recently, electricity and
2. Description of the Related Art As electronic devices have become smaller, lighter, and more multifunctional, the mounting density of semiconductor elements on printed circuit boards incorporated therein has increased. This high-density mounting inevitably increases the amount of heat radiation from the mounting substrate, and also increases the amount of heat radiation of electric / electronic devices.

For this reason, it is necessary to increase the heat resistance of the above-mentioned lead material, contact material and the like more than ever. However, recently, it has been pointed out that, as described above, a material obtained by plating a substrate of Cu or a Cu alloy with Sn or a Sn alloy cannot sufficiently satisfy the above-mentioned requirements.

That is, in the case of a lead material, there is a problem that high-temperature aging of a joint portion between a component lead and a solder after component mounting or a reduction in joint reliability between a component lead and an electrode of a mounting board in a heat cycle state. It is. In other words, in recent electronic devices incorporating a high-density mounting board, the amount of heat radiation and the temperature rise of the device are large, so that the lead material plated with Sn or Sn alloy has sufficient bonding reliability. There are many cases where it is not possible to obtain.

In the case of a contact material, when used in a high-temperature environment, the Cu component on the substrate surface and the Sn
It has been pointed out that alloying due to mutual thermal diffusion with the components and an increase in contact resistance due to oxidation and diffusion of the Cu component to the surface layer of the surface layer occur, thereby reducing the connection reliability with the partner material. ing.

The present invention solves the above-mentioned problems in the conventional material having Cu or a Cu alloy as a substrate and the surface of which is plated with Sn or an Sn alloy, and of course eliminates the adverse effect of Pb. That the surface layer is Sn
It has a lower melting point, excellent solderability, no whiskers, and high joint strength of the joint formed after soldering, and at the same time, it is difficult for the joint strength to decrease over time at high temperatures. It is suitable as a lead material, and also suppresses an increase in contact resistance even when used in a high-temperature environment, and does not cause a decrease in connection reliability with a mating material.
An object of the present invention is to provide a material for an electronic component, a method for manufacturing the same, and an electric / electronic component using the material.

[0026]

In order to achieve the above object, according to the present invention, a Cu layer, Ni or Ni alloy layer or an Ag layer is formed on at least the surface of a substrate made of Cu or Cu alloy. A surface layer comprising a Sn layer or a Sn alloy layer having a Cu content of 0.1 to 3% by weight and a thickness of 0.5 to 20 μm is formed via an intermediate layer having at least one layer. Materials for electric and electronic parts, particularly, a thickness of 0.1 to 0.1
1 μm Ni or Ni alloy layer and thickness 0.003 to 0.00
An Ag layer equivalent to 5 μm is laminated in this order,
The surface layer is formed on the layer, and the Sn alloy of the surface layer is made of a Sn—Ag alloy or Sn—Bi alloy.
A material for electric / electronic parts, wherein the material is a base alloy, and the surface layer is a layer subjected to a heat treatment or a reflow treatment.

Further, the present invention provides an electric / electronic component using the above-mentioned material.

Further, in the present invention, a Cu plating bath,
Using at least one selected from the group consisting of a Ni plating bath, a Ni alloy plating bath, an Ag plating bath, and a Bi plating bath, electroplating is performed on a substrate having at least a surface made of Cu or a Cu alloy. The present invention also provides a method for producing a material for electric / electronic parts, characterized in that electroplating is carried out using a Sn plating bath or a Sn alloy plating bath containing 0.2 to 50 ppm of Cu ions. After the electroplating, a method for producing a material for electric / electronic parts, in which the obtained material is subjected to a heat treatment or a reflow treatment, is provided.

[0029]

FIG. 1 is a sectional view showing an example A of a basic structure of a material of the present invention. This material A has a layer structure in which a Sn layer or a Sn alloy layer described later is formed as a surface layer 3 on a surface of a base 1 via an intermediate layer 2 described later.

Here, as the substrate 1 of the material A,
Any material may be used as long as at least its surface is formed of Cu or a Cu alloy. For example, Cu or Cu alloy material itself, carbon steel, Fe-Ni alloy,
Examples thereof include a core material made of an Fe-based material such as an Fe-Ni-Co-based alloy and stainless steel, the surface of which is coated with Cu or a Cu alloy. In the latter case,
The type of the core material and Cu or a Cu alloy formed on the surface thereof, in particular, the type of the Cu alloy are appropriately selected in consideration of the relationship between mechanical strength and conductivity required for the intended use of the part.

The shape of the base 1 is also appropriately selected, such as linear, plate, or strip, in accordance with the purpose of use as a part or the surface layer forming method described later.

The material A is a material in which the intermediate layer 2 is formed on the surface of the above-described base 1, and the surface layer 3 is further formed thereon.

The surface layer 3 has a Cu content of 0.1.
It is composed of an Sn layer (referred to as a CuSn-containing layer) of about 3% by weight or a Sn alloy layer (referred to as a Cu-containing Sn alloy layer) having a Cu content of 0.1 to 3% by weight.

In both the CuSn-containing layer and the CuSn-containing alloy layer, it is necessary that Cu is contained in an amount of 0.1 to 3% by weight. When mounted using, compared to the case of a component material having a surface layer formed of a Cu-free Sn layer or a Sn alloy layer, the bonding strength at the solder bonding portion is increased, and the bonding reliability is improved. Brought.

Further, since the surface layer contains Cu having a high conductivity, when this material is used as a contact material, the Cu contributes to lowering the contact resistance with a counterpart material, Furthermore, when soldering is performed, it contributes to the reduction of solder erosion and the improvement of the heat resistance of the solder joint, thereby realizing the improvement of the joint reliability. When this material is used as a lead material for an IC package,
The heat resistance of the solder joint is similarly improved, and the solder joint can be used in a high-temperature environment.

This is because, when Cu is contained in Sn or Sn alloy, the heat resistance including the creep characteristic of the surface layer 3 and the whisker resistance are improved. Since the rate of interdiffusion with Cu, which is the surface component of 1, and other elements of the surface layer is reduced, and the alloying of the two is suppressed, the temporal decrease in the bonding strength at the soldered joint is reduced, and as a result, This is considered to be a phenomenon in which the bonding reliability is improved.

However, the Cu content is 0.1% by weight.
If the amount is smaller, the above-listed effects will not be exhibited. If the amount is more than 3% by weight, the liquidus of the constituent material of the surface layer 3 will be excessively high. In No. 3, the Cu content should be set to 0.1 to 3% by weight since the solder wettability and the corrosion resistance are likely to be lowered due to the progress of Cu oxidation.

When the surface layer 3 is formed of a CuSn-containing alloy layer, the Sn alloy serving as a parent phase is formed of the above-described Sn alloy.
-Ag-based, Sn-Bi-based, Sn-In-based, Sn-Zn-based and the like can be used. In that case, although the Sn-Zn system is inexpensive, the diffusion rate of Zn is large, and the temporal decrease of the bonding strength at the solder bonding part is large, so that it is difficult to obtain high bonding reliability and the corrosion resistance is also poor. However, there is a problem that the Sn-In type is expensive and its use is limited. For this reason, it is preferable that the Sn alloy, which is the parent phase of the Cu-containing Sn alloy layer, be of an Sn-Ag type or a Sn-Bi type.

In the case of Sn-Ag system, Ag is 3.5% by weight.
Eutectic structure, the melting point of which is 221 ° C., and the surface layer formed of this alloy is only about 11 ° C. lower than the melting point when formed of metal Sn, and there is no inconvenience regarding heat resistance.

The Sn-Bi system is advantageous in terms of economy. In the case of the Sn-Bi system, the liquidus temperature decreases as the Bi content increases up to the eutectic point of 139 ° C. where the Bi content is 57% by weight. However, this means that
At the same time, it also means a decrease in heat resistance. Further, when the surface layer is formed of this alloy, the Bi content is about 5% by weight, bending workability is deteriorated and cracks are liable to be formed. Sometimes, the heat resistance of the soldered joints is reduced, and the bonding strength at the joints is reduced with time, resulting in reduced joint reliability.

For this reason, the surface layer 3 is made of Sn-A
When formed in a g-system, the alloy composition is Sn-1 to Sn-4.
% Ag alloy is preferable, and when formed of Sn-Bi alloy, the alloy composition is Sn-1 to 5% Bi.
Preferably, it is an alloy.

The thickness of the surface layer 3 is determined by the relationship between the field of use of the material, the required heat resistance, and the production cost. For example, in the case of exterior soldering of the outer lead portion of a semiconductor or IC package, in order to realize the reliability of the component mounting state by solder flow or reflow processing, or to secure the bonding reliability of the soldered joint, its thickness is required. Should be at least 5 μm. In the case of a contact material, if the thickness of the surface layer is less than 0.5 μm in the reflow-treated product, Cu on the substrate surface and S
Alloying by mutual diffusion with n progresses, and it becomes difficult to secure solder wettability and contact resistance at a low level.
When the thickness is large, the thickness of the surface layer is about 1.5 to 2.0 μm from the viewpoint of realizing uniform reflow treatment and the production cost, and the thickness of the surface layer is 2.0 μm in the case of the bright plating product in terms of the production cost. The degree is preferred. Furthermore, in the case of the outer lead outer solder, even if the thickness of the surface layer is too large, the performance reaches saturation and the production cost is increased, so the upper limit of the thickness is set to 20 μm. You. For this reason, the thickness of the surface layer in the material of the present invention is set to 0.5 to 20 μm.

As the intermediate layer 2 interposed between the surface layer 3 and the base 1, the following is selected.

First, the Cu layer 2A, and the layer structure of the material A1 in this case is shown in FIG.

The Cu layer 2A is capable of securing the adhesion between the surface of the substrate 1 and the surface layer 3 when the surface of the substrate 1 is a Cu-Zn-based alloy such as brass or copper. It is suitable. When the Cu layer 2A was interposed, the surface of the substrate 1 was rough or an oxide layer was interposed on the surface to form a surface layer made of a Sn layer or a Sn alloy layer on the surface. It is possible to prevent a phenomenon observed when a reflow treatment is performed later, that is, a phenomenon in which the surface layer is white and cloudy and a mirror gloss cannot be obtained, that is, a so-called "Sn repelling" phenomenon.

In any case, if the thickness of the Cu layer 2A is too thin, the above-mentioned effects cannot be obtained. If the thickness is too thick, the above-mentioned effects not only reach saturation, but also the Cu layer Diffusion begins to occur, causing a decrease in solder wettability of the surface layer, oxidation, discoloration, and an increase in contact resistance with a mating material, and the like.
It is preferable to set m.

The second intermediate layer is a Ni or Ni alloy layer 2B, and the layer structure of the material A2 in that case is shown in FIG.

The Ni or Ni alloy layer 2 B
Contributes to ensuring the adhesion between the substrate 1 and the surface layer 3, prevents the above-mentioned “Sn repelling”, and further reduces the C on the surface of the substrate 1.
It functions as a barrier for suppressing that u is thermally diffused into the surface layer 3 and alloyed with Sn.

When the intermediate layer 2B is formed of a Ni alloy, it is preferable that the Ni alloy exhibit the above-described barrier effect. For example, Ni alloys such as Ni—Co, Ni—P, and N
An iB-based alloy can be used, but it is preferable to use an alloy that can be electroplated from the viewpoint of material productivity and manufacturing cost, and from the viewpoint of ensuring adhesion between the substrate 1 and the surface layer. From this point of view, Ni-P-based alloys have a low current density for alloying during electroplating, Ni-B-based alloys are not so high, and Ni-Co-based alloys can be electroplated but are expensive. There is difficulty in point. However,
In the case of a material in which it is advantageous to form the surface layer by electroless plating, it is preferable to use the above-mentioned Ni-P system and Ni-B system. Given this,
Industrially, it is preferable to electroplate Ni alone in forming the intermediate layer 2B.

When the intermediate layer 2B is formed of Ni or a Ni alloy, Ni is also thermally diffused into the surface layer and alloyed with Sn to form a compound layer such as Ni ₃ Sn ₄ . However, its diffusion rate at a temperature of 200 ° C. or less is lower than that of Cu, and even if it diffuses to the surface layer of the surface layer 3, it does not oxidize and cause surface discoloration.

Therefore, in this layer structure, a Ni-Sn compound layer is often interposed at the interface between the intermediate layer 2B made of Ni or Ni alloy and the surface layer 3 made of Sn or Sn alloy. The thickness of the layer is determined by heat history such as a heat treatment or a reflow treatment, and further, a layer of a Cu—Sn compound may be included due to diffusion of Cu from the substrate surface.

The intermediate layer 2 made of Ni or Ni alloy
If the thickness of B is too small, the above-mentioned barrier effect is not exhibited. If the thickness is too large, not only the bending workability is reduced and cracks are increased but also the production cost is increased. It is preferable to set the thickness to 0.1 to 1 μm.

The third intermediate layer is an Ag layer 2C, and the layer structure of the material A3 in this case is shown in FIG.

When the intermediate layer 2C is an Ag layer, the material A3 in which the Ag layer 2C is interposed has a disadvantage due to oxidation of the surface layer even if the material is exposed to a high temperature environment for a long time. Therefore, the problem of an increase in contact resistance does not occur. On the contrary, by diffusing Ag into the surface layer 3, the effect of not only stabilizing the contact resistance but also decreasing it in many cases is obtained.

Even when the surface of the base 1 is formed of phosphor bronze, and the material A3 is exposed to a high temperature environment, the presence of the Ag layer 2C causes the base 1 and the surface to be in contact with each other. Peeling from the layer 3 does not occur. That is, this A
The g layer 2C is a layer that greatly contributes to ensuring the adhesion between the substrate 1 and the surface layer 3.

Therefore, this material A3 is suitable as a contact material used in a field where high heat resistance is required, such as an electrical component in a field related to an automobile.

If the thickness of the Ag layer 2C is too small, it is difficult to obtain the above-mentioned effects. If the thickness is too large, the effect not only reaches saturation but also increases the manufacturing cost. It is preferable to set the thickness to 1 to 1 μm.

As shown in FIG. 5, the fourth intermediate layer 2D is composed of the Ni or Ni alloy layer 2 formed on the surface of the substrate 1.
It has a two-layer structure including B and an Ag layer 2C formed thereon.

With the material A4 having the intermediate layer 2D, the effect of the Ni or Ni alloy layer 2B described with respect to the material A2 and the effect of the Ag layer 2C described with respect to the material A3 are simultaneously exhibited. It is more effective in improving the bonding reliability of solder joints, suppressing the increase in contact resistance in high-temperature environments, suppressing surface oxidation and discoloration, and is useful as either a lead material or a contact material. Material.

In the above-described two-layer structure, the thickness of the Ni or Ni alloy layer 2B located on the side of the base 1 is set to 0.1 to 1 μm in order to exert its barrier effect and ensure its bending workability. It is preferable to set the thickness, and the thickness of the Ag layer 2C formed thereon may not be as thick as that of the material A3, and may be 0.003 to 0.5.
If it is within the range of μm, the above-mentioned effects can be sufficiently obtained.

The materials A1, A thus produced
When reflow treatment is performed on A2, A3, and A4, not only can the presence of whiskers that may occur when the surface layer is formed of a CuSn-containing layer be eliminated, but also the surface layer 3 and the substrate 1 can be eliminated. Sn and Cu between the surfaces of
This is preferable because the diffusion speed of the metal is reduced to convert the material into a material having excellent heat resistance, and after all, the bonding reliability at the solder bonding portion can be increased and the increase in contact resistance can be suppressed.

Although there is no disadvantage even if Cu is contained in the above-mentioned intermediate layer, all of the constituent materials of these intermediate layers do not have a low melting point like Sn or Sn alloy. It hardly contributes to the improvement of heat resistance, but rather, the inclusion of Cu may cause a decrease in corrosion resistance.

The material of the present invention can be manufactured by electroplating.

For example, when manufacturing the material A1, electroplating is performed using a Cu plating bath, and
The u-plated layer 2A is formed, and electroplating is further performed thereon using a Sn plating bath or a Sn alloy plating bath to form a surface layer having a desired thickness.

At this time, in order to make the surface layer 3 contain Cu in an amount of 0.1 to 3% by weight, an Sn plating bath or S
It is necessary that the n-alloy plating bath contains 0.2 to 50 ppm of Cu ions. If the Cu ion content is out of the above range, the Cu content in the Sn plating layer or the Sn alloy plating layer, which is the surface layer 3, may be not more than 0.1 depending on plating conditions such as current density and plating bath temperature.
This is because it does not become 1 to 3% by weight.

Examples of the Cu plating bath include a copper sulfate-based plating bath and a copper cyanide-based plating bath commonly used in the field of Cu plating. Also,
Examples of the Sn plating bath or Sn alloy plating bath include conventionally known ones mainly composed of tin sulfate and those mainly composed of organic acid tin.

In the case of producing the material A2, electroplating is performed using a Ni plating bath or a Ni alloy plating bath to form a Ni plating layer or Ni alloy plating layer 2B having a desired thickness on the substrate 1, and further thereon. Electroplating may be performed using the above-described Sn plating bath or Sn alloy plating bath to form the surface layer 3 having a desired thickness.

As the Ni plating bath or Ni alloy plating bath, conventionally known baths mainly containing nickel sulfate or nickel chloride, and those mainly containing nickel sulfamate can be used.

When the material A3 is manufactured, electroplating is performed using an Ag plating bath to form an Ag plating layer 2C having a desired thickness on the substrate 1, and further thereon, the above-described Sn plating bath or Sn alloy plating is formed. The surface layer 3 may be formed by performing electroplating using a bath.

Examples of the Ag plating bath include a conventionally known silver cyanide and potassium silver cyanide-based bath or a commercially available cyanide-free bath.

When the material A4 is manufactured, the above-described N
Electroplating is performed using an i-plating bath or a Ni-alloy plating bath to form a Ni-plated layer or a Ni-alloy-plated layer 2B having a desired thickness on the substrate 1, and electroplating is performed thereon using the above-described Ag plating bath. Then, an Ag plating layer 2C is formed, and electroplating is further performed thereon using the above-described Sn plating bath or Sn alloy plating bath to form the surface layer 3.

When the surface layer 3 is formed of a Sn alloy layer, the following method can be employed in addition to the method of forming the surface layer 3 using the Sn alloy plating bath as described above.

For example, when forming a Sn—Ag alloy layer, there is a method in which Ag plating is performed first, and then Sn plating is performed. In forming the Sn—Bi alloy layer, there is a method of performing Bi plating first, and then performing Sn plating. Furthermore, a heat treatment can be performed to promote the diffusion alloying of the components of these layers. At this time, there is a method of proceeding from Sn plating first, but if Ag or Bi having a noble deposition potential is plated thereon, surface unevenness may occur, so this method is not a very preferable method.

The materials A1, A thus produced
When reflow treatment is performed on A2, A3, and A4, not only can the presence of whiskers that may occur when the surface layer is formed of a CuSn-containing layer be eliminated, but also the surface layer 3 and the substrate 1 can be eliminated. Sn and Cu between the surfaces of
This is preferable because the diffusion speed of the solder joint decreases, and eventually, the joint reliability at the solder joint portion can be increased and the increase in contact resistance can be suppressed.

This heat treatment or reflow treatment is usually performed in a non-oxidizing atmosphere such as an N ₂ atmosphere or a reducing atmosphere such as an atmosphere containing CO or H ₂ . When the material is in the form of a line or a strip and is subjected to continuous processing, it is preferable to use a hot air blowing furnace.

[0076]

EXAMPLES Examples 1 to 21 and Comparative Examples 1 to 9 A sheet material whose surface is made of an alloy having the composition shown in Tables 1 to 4 was subjected to alkali cathode degreasing and pickling with 10% sulfuric acid in that order. , A first plating bath, a second plating bath, and a third plating bath.
Materials A1, A2, A3, and A4 in which the plating layers shown in Tables 1 to 4 were formed as the surface layer 3 were manufactured.

The Cu plating bath was a copper sulfate plating bath, the Ni plating bath was a nickel sulfamate plating bath, and the Ag plating bath was Dyne Silver AG-PL.
3O (trade name, manufactured by Daiwa Kasei Co., Ltd.) was used. Also, S
An organic acid tin plating bath was used as the n plating bath.

The thickness of each of the obtained material surface layers is calculated from the dissolution potential and the amount of dissolution electricity by applying the anodic dissolution method.
Quantitative analysis was performed using the correction method. The above results are shown in Tables 1 to 4.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3]

[0082]

[Table 4]

The surface of each material was visually observed. Each material was kept in the air at 50 ° C. for 2500 hours, and then observed under a microscope to check for the presence of whiskers.
Was conducted to evaluate the bending workability at that time.

Further, a contact current at a low temperature was measured by applying a current of 10 mA to 10 pieces of each material while pressing the Ag probe with a load of 100 g. Then, the contact resistance after subjecting each material to a heat treatment in which it was kept at 150 ° C. for 100 hours in the atmosphere was measured in the same manner.

Table 5 summarizes the above results.

[0086]

[Table 5]

Examples 22 to 31 and Comparative Examples 10 to 19 Plates whose surfaces are made of alloys having the compositions shown in Tables 6 and 7 were sequentially subjected to alkaline cathode degreasing and pickling with 10% sulfuric acid. A plating bath containing the plating baths shown in Tables 6 and 7 was sequentially run to produce a material in which the plating layer shown in Tables 6 and 7 was formed as the surface layer 3.

In addition, Cu plating bath, Ni plating bath, Ag plating bath,
The same plating bath and Sn plating bath as those in Examples 1 to 21 were used. As the Sn alloy plating bath, Dyne TINSIL-SBB bath (trade name, Daiwa Kasei Co., Ltd.)
And a PF bath (trade name, Sn-Bi plating bath manufactured by Ishihara Yakuhin Co., Ltd.).

The thickness and composition of the surface layer of each material were determined in Examples 1 to
The measurement was performed in the same manner as in Example 21.

The obtained material was cut into a 25 mm square, and a copper coated steel wire having a diameter of 3 mm was joined to the test piece by soldering. As the solder, a eutectic solder of Sn-37% Pb,
Two types of -3.5% Ag eutectic solder were used. The size of the solder joint was constant at a diameter of 6 mm.

Next, the pull strength (T ₀ ) between each sample and the copper-coated steel wire was measured at room temperature. Then, the solder bonding material is aged in air at a temperature of 150 ° C. for 500 hours to perform a deterioration accelerating treatment. At that time, a pull strength (T ₁ ) between each sample and the copper-coated steel wire is measured, and (T ₁ ) ₀
−T ₁ ) × 100 / T ₀ was calculated to be the deterioration rate (%) of the joining strength at the solder joint.

The above results are collectively shown in Tables 6 and 7.

[0093]

[Table 6]

[0094]

[Table 7]

Examples 32 to 35, Comparative Examples 20 and 21 A copper-coated steel wire having a diameter of 0.5 mm was placed in a cathode degreasing tank, a pickling tank,
The surface layers shown in Table 8 were formed by sequentially running in a plating tank.

Next, each lead wire was inserted into the through-hole of the printed circuit board having a Cu pad having an outer diameter of 3 mm formed around the through-hole having a diameter of 1.2 mm, and after applying a flux, a temperature of 250 ° C. The printed circuit board was immersed in the dipping type solder bath for 3 seconds, then pulled up, and allowed to cool naturally.

The solder used in Examples 22 to 31 was used.
The same two types were used.

The rate of deterioration of the bonding strength between the Cu pad and the copper-coated steel wire in this material was calculated in the same manner as in Examples 22 to 31. Table 8 shows the results.

[0099]

[Table 8]

The following is clear from the above results.

(1) As is clear from Tables 1 to 5, the materials of the present invention are all excellent in heat resistance, and the increase in contact resistance is suppressed even after heat treatment.

For example, as is clear from comparison between Example 1 in which the surface layer is formed of a CuSn-containing plating layer and Comparative Example 2 in which the surface layer does not contain Cu, both have the same intermediate layer. In spite of the provision of, the former suppresses an increase in contact resistance, but the latter significantly increases. This proves the effect of forming the surface layer with the Sn-containing Sn plating layer.

Further, as is apparent from comparison between Example 10 and Comparative Example 6, although both of them have the same base and surface layer, Example 10 in which the intermediate layer is interposed is used. Although the material is in a good state and the contact resistance is suppressed from increasing, Comparative Example 6 having no intermediate layer has
n is strongly repelled and fogged, which makes it difficult to commercialize the product. From this, it is understood that an intermediate layer should be interposed between the substrate and the surface layer.

(2) Even when the surface layer is a CuSn-containing layer, if the Cu content is more than 3% by weight, Sn repelling and fogging occur as in Comparative Example 5. , Cu content should be regulated up to 3% by weight. For that purpose, the Cu ion concentration in the plating bath should be 50 ppm or less.

Even when the Cu content is 3% by weight or less, when the thickness becomes 0.4 μm, the contact resistance increases as in Comparative Example 8. For this reason, the thickness of the surface layer composed of the CuSn-containing layer is 0.5 μm.
It is understood that the above should be performed.

(3) As is clear from Tables 6 and 7, all of the materials of the present invention have a small rate of deterioration of the joining strength at the solder joints and have high joining reliability.

In particular, when the surface layer is made of Sn-Ag or Sn-B
i-type (Examples 26 and 28) and an intermediate layer composed of a Ni plating layer as a lower layer and an Ag layer laminated thereon between the surface layer and the substrate (Example 29) Is
It is preferable that the rate of deterioration of the bonding strength is further reduced as compared with the materials of the other examples.

(4) As is apparent from Table 8, when the surface layer has a two-layer structure of a CuSn-containing layer and a Sn-Ag-based or Sn-Bi-based Cu-Sn-containing alloy layer, and the entire surface is subjected to heat treatment. As in the case of Examples 32 and 34, the deterioration of the bonding strength at the solder bonding portion is further reduced, which is preferable.

[0109]

As is apparent from the above description, the material of the present invention does not adversely affect the environment because Pb is not contained in the Sn or Sn alloy layer. The deterioration of the bonding strength is small, and the material is excellent in heat resistance. Therefore, this material
As materials for various electric and electronic parts, particularly lead materials used for semiconductor devices, and contact materials for terminals, connectors, switches, and the like, each part using the same has great industrial value.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a layer structure of another material A1 of the present invention.

FIG. 3 is a sectional view showing a layer structure of another material A2 of the present invention.

FIG. 4 is a sectional view showing a layer structure of another material A3 of the present invention.

FIG. 5 is a sectional view showing a layer structure of another material A4 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base | substrate 2 Intermediate layer 2A Cu layer 2B Ni layer or Ni alloy layer 2C Ag layer 3 Surface layer (CuSn containing layer or CuSn containing alloy layer)

Claims (7)

[Claims] 1. The method according to claim 1, wherein the Cu content is 0.1 to 0.1 through an intermediate layer having at least one Cu layer, Ni or Ni alloy layer or at least one Ag layer on the surface of the substrate whose surface is made of Cu or Cu alloy. 0.5 to 2% by weight which is 3% by weight
A material for electric / electronic parts, wherein a surface layer made of a Sn layer or a Sn alloy layer having a thickness of 0 μm is formed. 2. The method according to claim 1, wherein the thickness of the substrate is 0.1 to 1 μm.
Ni or Ni alloy layer and thickness 0.003-0.5 μm
2. The material for electric / electronic parts according to claim 1, wherein a substantial Ag layer is laminated in this order, and said surface layer is formed on said Ag layer. 3. The electric / electronic component material according to claim 1, wherein the Sn alloy of the surface layer is a Sn—Ag alloy or a Sn—Bi alloy. 4. The material for electric / electronic parts according to claim 1, wherein said surface layer is a layer subjected to a heat treatment or a reflow treatment. 5. An electric / electronic part using the material for electric / electronic parts according to claim 1. 6. At least one surface selected from the group consisting of a Cu plating bath, a Ni plating bath, a Ni alloy plating bath, an Ag plating bath, and a Bi plating bath.
electroplating using a Sn plating bath or a Sn alloy plating bath each containing 0.2 to 50 ppm of Cu ions after performing electroplating on a substrate made of u or Cu alloy.・ Methods of manufacturing materials for electronic components. 7. The method for producing a material for electric / electronic parts according to claim 6, wherein after the second electroplating is performed, the obtained material is subjected to a heat treatment or a reflow treatment.