JPH11350189A - Material for electrical and electronic parts, its production and electrical and electronic parts using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart excellent solderability to a material and to improve the strength of a joint part after soldering by providing the surface of a substrate of Cu or a Cu alloy with a surface layer consisting of Sn alloy phases contg. Ag3 Sn via an intermediate layer of Ni or an Ni alloy. SOLUTION: On the surface of a substrate, a surface layer composed of an Sn or Sn alloy layer is formed via an intermediate layer composed of an Ni or Ni alloy layer. As for the substrate, all may be used if its surface is formed by Cu or a Cu alloy. The surface layer is composed of Sn or Sn alloy phases of 0.5 to 20 μm thickness contg. an Ag3 Sn (ε phase) compd. The Ag3 Sn compd. is in a stable condition in the Sn or Sn alloy layer and does not diffuse and move in the surface layer on a temp. level in the vicinity of a room temp. The intermediate layer is formed by an Ni or Ni alloy layer. This intermediate layer secures the adhesion between the surface of the substrate and the surface layer. The content of the Ag3 Sn compd. in the surface layer is preferably 0.5 to 5 wt.% expressed in terms of Ag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for electric / electronic parts, a method for manufacturing the same, and an electric / electronic part using the material, and more particularly, to a lead material for various semiconductor devices, terminals, connectors and switches. The present invention relates to a material suitable for use as a contact material, 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 semiconductor 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 the material component is soldered and mounted on a circuit board, the board material (resin) needs to have higher heat resistance, and at that time, In addition, Sn itself is oxidized and solderability is likely 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 a Sn alloy containing no Pb, specifically, a Sn-Ag system, a Sn-Bi system,
The transition to Sn-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 high or low as compared with the Sn-Pb-based alloy. Cu, a constituent material of
Such a problem is that heat is 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-based alloy is inferior in heat resistance, easily causes thermal diffusion of Bi to the surface of the substrate, and is inferior in bending workability, so that cladding is 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 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-mentioned object, according to the present invention, Ni or Ni is added to the surface of a substrate having at least a surface made of Cu or a Cu alloy.
Through an intermediate layer composed of an alloy layer, all of them are Ag ₃ Sn
(Ε phase) Sn containing compound and having a thickness of 0.5 to 20 μm
The present invention provides a material for electric / electronic parts, characterized in that a layer or a surface layer comprising a Sn alloy phase is formed. In particular, the content of the Ag ₃ Sn (ε phase) compound in the surface layer is 0.5 to 5% by weight in terms of Ag, and the surface layer further contains 0.1 to 3% by weight of Cu. %, And wherein the surface layer is a layer subjected to a heat treatment or a reflow treatment.

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

Further, in the present invention, at least the surface is made of Cu by using a Ni plating bath or a Ni alloy plating bath.
Alternatively, electroplating is performed on a substrate made of a Cu alloy, and then electroplating is performed using a Sn plating bath or a Sn alloy plating bath containing 0.2 to 10,000 ppm of Ag ions. A method for producing a material for use is provided, wherein preferably, the Sn plating bath or the Sn alloy plating bath contains 0.2 to 5 Cu ions.
The present invention provides a method for producing a material for electric / electronic parts, which contains 0 ppm, and is subjected to a heat treatment or a reflow treatment on the material after the second electroplating.

[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 is composed of a Sn layer or a Sn alloy layer containing an Ag ₃ Sn (ε phase) compound.

The above Ag ₃ Sn (ε phase) compound is
It is in a very stable state in the n layer or the Sn alloy layer, and does not diffuse and move in the surface layer at least at a temperature level near room temperature. The Ag ₃ Sn (ε phase) compound improves the heat resistance including the creep characteristics of the Sn layer or the Sn alloy layer, and at the same time, Sn as the main component of the surface layer 3 and Cu as the main component of the substrate surface. It is considered that the function of suppressing the alloying of both elements by lowering the mutual diffusion rate of the element and the surface layer with other elements is considered.

For this reason, when this material A is used as a lead material, for example, when it is joined to a printed circuit board using solder, the surface layer is made of a Sn layer or a Sn alloy layer containing no Ag ₃ Sn (ε phase) compound. The joining strength at the solder joint is higher than that of the formed lead material, and the decrease in the joining strength at the joint with the lapse of time is small, and the joining reliability is improved.

When the material A is used as a contact material, the heat resistance of the surface layer 3 is improved, and the thermal diffusion of Cu from the surface of the base toward the surface layer of the surface layer is suppressed. As a result, the surface oxidation of the surface layer 3 is less likely to occur, and the increase in contact resistance is suppressed, and the problem of reduced connection reliability with the mating material is less likely to occur.

Ag ₃ Sn (ε contained in the surface layer 3
The above function of the phase) compound is effectively exerted when its content is 0.5% by weight or more in terms of Ag. As the content increases, the heat resistance of the surface layer 3 improves, but the content corresponding to the Ag content of Sn-3.5% Ag, which is the eutectic composition in the Sn-Ag based alloy, is increased. If it exceeds, the liquidus of the Sn layer or Sn alloy layer constituting the surface layer 3 will rise sharply. Therefore, Ag ₃ Sn (ε
The content of the (phase) compound is such that the surface layer 3 has a melting point of Sn (232
C)), the content is preferably such that the heat resistance is not exceeded. Specifically, the upper limit of the content of the Ag ₃ Sn (ε phase) compound is about 5% by weight in terms of Ag. Is set. At this time, the bendability of the material is good, the cost is not so high, and the material is industrially balanced.

The Sn layer or S layer constituting the surface layer 3
It is preferable that Cu is further contained in the n-alloy layer in an amount of 0.1 to 3% by weight.

When such a treatment is performed, for example, when the manufactured component material is mounted on a printed circuit board using solder, the component material having a surface layer formed of a Sn layer or Sn alloy layer containing no Cu is used. Compared with the case, the joining strength at the solder joint is higher, and the joining reliability is improved.

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 the partner 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 improving the joint reliability. Further, when this material is used as a lead material for an IC package, the heat resistance of the solder joint is similarly improved, so that it can be actually used even in a high-temperature environment.

This is because, when Cu is contained in the Sn or Sn alloy, the heat resistance including the creep characteristic of the surface layer 3 and the whisker resistance are improved, and the main component of the surface layer 3, Sn and the substrate, is 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 is preferably set to 0.1 to 3% by weight since the solder wettability and the corrosion resistance are likely to decrease due to the progress of Cu oxidation. The Ag ₃ Sn in the surface layer 3 described above is preferable. The (ε phase) content of Ag as a compound and the content of Cu can be quantitatively analyzed by a ZAF correction method using an electron beam microanalyzer, and the presence of compounds of Ag ₃ Sn, Cu ₃ Sn, and Cu ₆ Sn ₅ can be determined. Can be known by X-ray diffraction.

When the surface layer 3 is formed of a Sn alloy layer, the Sn alloy serving as the parent phase is the above-described Sn-Bi alloy.
System, Sn-In system, Sn-Zn system, or the like can be used. In that case, the Sn-Zn system is inexpensive,
The diffusion rate of n is large, and the temporal decrease in the bonding strength at the soldered joint becomes large, so that it is difficult to obtain high bonding reliability, and the corrosion resistance is also poor.
There is a problem that the Sn-In system is expensive and its use is limited. For this reason, it is preferable that the Sn alloy, which is the parent phase of the Sn alloy layer, is of the Sn-Bi type.

The Sn-Bi system is also advantageous in terms of economy. In the case of this Sn-Bi system, the Bi content is 57% by weight.
Up to 139 ° C., the liquidus temperature decreases as the Bi content increases. However, this also implies a decrease in heat resistance. When the surface layer is formed of this alloy, when the Bi content starts to exceed about 5% by weight, bending workability is deteriorated and cracks are easily formed. When joined by solder, the heat resistance of the solder joint decreases,
The bonding strength at the bonding portion also decreases with time, and the bonding reliability decreases.

For this reason, when the Sn-Bi-based alloy is formed, the alloy composition is preferably a Sn-1 to 5% Bi 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 manufacturing cost. For example, in the outer soldering process of the outer lead portion of the IC package, in order to realize the reliability of the component mounting state by the flow or the reflow process by the solder or to secure the joining reliability of the soldered joint, the thickness is at least. It must be 5 μm. In the case of a contact material, in the reflow-processed product, if the thickness of the surface layer is smaller than 0.5 μm, Cu on the substrate surface or Ni of the intermediate layer 2 during the reflow process is reduced.
Alternatively, alloying by interdiffusion between the Ni alloy and Sn of the surface layer progresses, and it becomes difficult to secure solder wettability and contact resistance at a low level. In terms of manufacturing cost, the thickness of the surface layer is 1.
The thickness of the surface layer is preferably about 5 to 2.0 μm, and the thickness of the surface layer is preferably about 2.0 μm in the case of a bright plated product from the viewpoint of manufacturing cost. 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.

The intermediate layer 2 interposed between the surface layer 3 and the substrate 1 is formed of a Ni layer or a Ni alloy layer.

The intermediate layer 2 made of a Ni layer or a Ni alloy layer has a substrate 1 whose surface is made of Cu--Zn such as brass or copper.
In the case of a base alloy, the adhesion between the surface of the substrate 1 and the surface layer 3 is ensured. When the intermediate layer 3 is not present, the surface of the substrate 1 is rough, Is observed when a reflow process is performed after forming a surface layer made of a Sn layer or a Sn alloy layer on the surface of a substrate with an oxide layer interposed therebetween, that is, the surface layer becomes white and cloudy and the mirror gloss becomes low. It functions to prevent a phenomenon that cannot be obtained, that is, a so-called "Sn repelling" phenomenon.

Further, Cu, which is a surface component of the substrate 1, diffuses into the surface layer 3 and becomes alloyed with Sn, ie, oxidization and discoloration of the surface, deterioration of solderability, deterioration of solderability, and the like. It also functions as a barrier for preventing or suppressing inconveniences such as an increase in contact resistance with the material.

When the intermediate layer 2 is formed of a Ni alloy,
As the Ni alloy, those exhibiting the above-described barrier effect are preferable. For example, Ni-Co, Ni-P, Ni-
B-based alloys and the like can be mentioned, but from the viewpoint of material productivity and manufacturing cost, and from the viewpoint of ensuring the adhesion between the substrate 1 and the surface layer, it is preferable to use an alloy which can be electroplated.
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. Therefore, it is industrially suitable to form the intermediate layer 2 by electroplating Ni alone.

When the intermediate layer 2 is formed of Ni or a Ni alloy, Ni is also thermally diffused to the surface layer and alloyed with Sn.
A layer of a compound such as Ni ₃ Sn ₄ is formed. 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 2 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 is too thin, the barrier effect described above will not be exhibited.If the thickness is too large, not only the bending workability of the material will decrease and the occurrence of cracks will increase but also the production cost will increase. It is preferable to set the thickness to 0.1 to 1 μm.

FIG. 2 is a sectional view showing another material B of the present invention.

Unlike the material A in which the surface layer 3 'is the material A described above, the material B does not consist of the Sn layer or the Sn alloy layer alone but in the thickness direction, as will be described below. It is a material having a layer structure in which various kinds of layers are laminated. In the layer structure, the interface between the various layers is
In some cases, the interface may not be apparent due to the interdiffusion of the components of each layer.

Examples of such a layer structure include the following.

I) The lower layer 3'b of the surface layer 3 'is made of Ag ₃ S
It consists n (epsilon phase) containing no compound Sn or Sn alloy, the upper portion 3'a is Ag ₃ Sn (epsilon phase) layer of Sn or a Sn alloy containing compound; lower part of the ii) the surface layer 3 ' 3′b is made of Sn or a Sn alloy containing an Ag ₃ Sn (ε phase) compound, and the upper layer portion 3′a is made of Sn not containing an Ag ₃ Sn (ε phase) compound.
Or a layer made of a Sn alloy;

In the case of the material B, the content of the Ag ₃ Sn (ε phase) compound in the entire surface layer 3 ′ is as follows, regardless of whether the surface layer 3 ′ has any of the above-mentioned layer structures i) and ii). Ag
Preferably, the amount is 0.5 to 5% by weight in terms of reduced amount.

When the surface layer 3 ′ has the layer structures i) and ii), the bendability as a material is improved, peeling from the substrate 1 is less likely to occur, and the manufacturing cost can be reduced. It is advantageous.

Further, in the case of this material B, when heat treatment or reflow treatment is performed, or when the material B is welded to an aluminum wire,
The heat at that time causes the above-mentioned layer structure to be fused and Ag or another element such as Bi to be in a diluted state, so that a decrease in the strength of the joint at the time of soldering is suppressed, for example, to prevent disconnection. This is preferable in that respect.

In particular, in the case of the above-mentioned layer structure i),
This is preferable because the above-mentioned effects are effectively exhibited. In that case, of the total thickness of the surface layer 3 ′, 0.5 to 5 μm
It is preferable that the Ag ₃ Sn (ε phase) compound is contained in the surface layer of the degree.

All of these materials can be easily manufactured with high quality by electroplating.

In the case of manufacturing the material A, for example, first, electroplating is performed using a Ni plating bath or a Ni alloy plating bath, and a Ni plating layer or N
An i-alloy plating layer 2 is formed.

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.

Then, Ag ions were added to 0.2 to 10000 p.
pm-containing Sn plating bath or 0.2 to 0.2% Ag ions
Electroplating may be performed using an Ag alloy plating bath containing 10,000 ppm, and the above-described surface layer 3 may be formed on the above-described Ni plating layer or Ni alloy plating layer.

At this time, the deposition potential of Ag is more noble than that of Sn, so that despite the small content of Ag ions in the plating bath, the plating layer deposited on the substrate surface has a small amount of Ag. % Of Ag ₃ Sn eutectoid Sn plating layer. Ag in this plating layer
_In order to keep the amount of ₃ Sn (ε phase) compound formed within the above-mentioned range of 0.5 to 5% by weight (in terms of Ag), it depends on plating conditions such as current density and bath temperature and bath type. ,In general,
Ag concentration in the plating bath used is 0.2 to 10,000p
need to be pm.

At this time, when the plating bath further contains Cu ions, the Cu is folded together with the electroplated plating layer (Ag-Sn alloy layer) on the substrate surface, and the heat resistance is higher than when only the Ag-Sn alloy is used. It becomes a plating layer with more excellent properties. As described above, the Cu content in this plating layer is set to be 0.
In order to control the concentration in the range of 1 to 3% by weight, it is necessary to control the concentration of Cu ions in the plating bath used to 0.2 to 50 ppm.

In the case of manufacturing the layer structure of the above-mentioned i) of the material B, the substrate on which the Ni plating layer or the Ni alloy plating layer has already been formed is replaced with an Ag plating-free Sn plating bath or Sn alloy bath. By immersing in a plating bath and performing electroplating, a Sn plating layer or a Sn alloy plating layer containing no Ag ₃ Sn (ε phase) compound is formed on the surface of the substrate. Next, electroplating was performed using a Sn plating bath or a Sn alloy plating bath containing Ag ions, and A
A Sn plating layer or a Sn alloy plating layer containing a g ₃ Sn (ε phase) compound is formed, and a desired surface layer 3 ′ is obtained here.

After completion of the entire electroplating, the obtained material is subjected to a heat treatment or a reflow treatment.
The components of the alloy are interdiffused between the plating layers and converted into a surface layer 3 'having higher adhesion.

In the case of manufacturing the layer structure of ii), the lower layer portion 3'b is formed by a Sn plating bath or a Sn alloy plating bath containing Ag ions, contrary to the case of the layer structure of i).
Then, the upper layer portion 3'a may be formed thereon using a Sn plating bath containing no Ag ions or a Sn alloy plating bath. Then, the target surface layer 3 'may be formed by subjecting the entire surface to a heat treatment or a reflow treatment so that the alloy components are mutually diffused between the plating layers.

When the materials A and B manufactured as described above are subjected to a reflow treatment, for example, the surface layer becomes an Sn layer or an S layer.
In addition to not only eliminating the presence of whiskers that may occur when the whiskers are formed with the n alloy layer, the diffusion rate of Sn and Cu between the surface layer 3 and the surface of the base 1 decreases, and eventually, the solder It is preferable because the joining reliability at the joining portion can be increased and the increase in contact resistance with the counterpart material 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 shape of a line or a strip and is subjected to continuous processing, it is preferable to use a heating furnace of a hot-air blowing system.

[0073]

Examples 1 to 20 and Comparative Examples 1 to 7 A sheet material whose surface is made of an alloy having the composition shown in Tables 1 to 3 was subjected to alkali cathode degreasing and pickling with 10% sulfuric acid in that order. , A plating bath containing an intermediate layer plating bath and a surface layer plating bath.
The material A and the material B in which the plating layer indicated by No. was formed as the surface layer 3 were manufactured.

The nickel plating bath was nickel sulfamate plating bath, the Ag plating bath was Dyne Silver AG-PL3O (trade name, manufactured by Daiwa Kasei Co., Ltd.), and the Sn alloy plating bath was IG0214 ( Trade name, Sn-Ag alloy plating bath manufactured by Dipsol Co., Ltd., and Soft Alloy LM (trade name, Sn-Bi alloy plating bath manufactured by Uemura Kogyo Co., Ltd.) were used, respectively.

The thickness of the surface layer of each of the obtained materials is calculated from the dissolution potential and the amount of dissolution electricity by applying the anodic dissolution method.
Quantitative analysis was performed using the F correction method. The above results are shown in Tables 1 to 3.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

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

Further, 10 mA was applied to 10 pieces of each material while the Ag probe was pressed with a load of 100 g, and the contact resistance at a low temperature was measured. 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.

The above results are shown in Table 4 collectively.

[0082]

[Table 4]

Examples 21 to 31 and Comparative Examples 8 to 13 A sheet material whose surface is made of an alloy having the composition shown in Tables 5 and 6 was subjected to alkali cathode degreasing and pickling with 10% sulfuric acid in that order. The plating baths containing the plating baths shown in Tables 5 and 6 were sequentially run to produce a material in which the plating layer shown in Tables 5 and 6 was formed as the surface layer 3.

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 20.

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 5 and 6.

[0088]

[Table 5]

[0089]

[Table 6]

Examples 32-36, Comparative Examples 14-18 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 Tables 7 and 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, the temperature was increased to 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 solders used in Examples 21 to 31 were used.
The same two types were used.

The deterioration rate 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 21 to 31. The results are shown in Tables 7 and 8.

[0094]

[Table 7]

[0095]

[Table 8]

The following is clear from the above results.

(1) As is clear from Tables 1 to 4, the materials of the present invention are all excellent in heat resistance, and the increase in the contact resistance is suppressed even after the heat treatment.

[0098] For example, the Ag ₃ Sn (ε phase) Example 2 and the surface layer is composed of free CuSn plating layer compound is contained in the surface layer are contained in Ag ₃ Sn (ε phase) Compound As is clear from comparison with Comparative Example 5 in which the two layers were similarly provided with an intermediate layer of Ni, the former had a lower contact resistance after heat treatment, whereas the latter had a lower contact resistance. Resistance is rising. This proves the effect of including the Ag ₃ Sn (ε phase) compound in the surface layer.

Further, as is apparent from comparison between the third embodiment and the sixth embodiment, even when the thickness of the surface layer is the same, the third embodiment is different from the third embodiment.
When Cu is contained in the surface layer as in the case (1), the deterioration rate of the bonding strength is reduced.

(2) As is clear from the comparison between the examples and the comparative examples 1, 4, and 6, any of the materials without the intermediate layer has a poor surface condition, and the contact resistance cannot be measured. It is in a state. Then, even when the intermediate layer is interposed as in Comparative Example 2, when the intermediate layer is Cu, the contact resistance after the heat treatment is significantly increased.

From the above, it is apparent that the intermediate layer is interposed and that the intermediate layer is made of Ni.

(3) As can be seen from Tables 5, 6, 7 and 8, the substrate composed of Sn layer and Sn-Ag layer
The materials (Examples 25, 26, 27, and 35) in which the plating layer having the layer structure is formed as the surface layer also have a small deterioration rate of the bonding strength. Further, when a plating layer having a two-layer structure of a Sn layer and an Ag layer is formed on the surface of the base or further subjected to a heat treatment (Examples 26, 27, 28 and 31), Sn and Ag mutually diffuse and diffuse. It becomes a single surface layer, and also in this case, the deterioration rate of the bonding strength is small. Further, even when Cu is contained during plating and reflow treatment is performed, a surface layer having a one-layer structure is formed, and the deterioration rate of the bonding strength in that case is also small (Example 36).

[0103]

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 layer or the Sn alloy layer. The deterioration of the bonding strength is small, and the material is excellent in heat resistance. Therefore, this material is used as a material for various electric and electronic parts, especially as a lead material used for semiconductor devices, and as a contact material for terminals, connectors, switches and the like, and parts using the same have 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 B of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Intermediate layer 3, 3 'Surface layer 3'a Upper layer part 3'b Lower layer part

Claims (8)

[Claims] 1. A method of manufacturing a semiconductor device comprising: a substrate having at least a surface made of Cu or a Cu alloy; and a layer containing an Ag ₃ Sn (ε phase) compound having a thickness of 0.5 through an intermediate layer made of a Ni or Ni alloy layer. A material for electric / electronic parts, wherein a surface layer made of a Sn layer or a Sn alloy layer having a thickness of about 20 μm is formed. 2. The Ag ₃ Sn (ε) in the surface layer
2. The material for electric / electronic parts according to claim 1, wherein the content of the phase) compound is 0.5 to 5% by weight in terms of Ag. 3. The surface layer further contains 0.1 to 3 Cu.
The material for electric / electronic parts according to claim 1 or 2 which is contained by weight. 4. The electric / electronic component material according to claim 1, wherein said surface layer is a layer subjected to a heat treatment or a reflow treatment. 5. An electric / electronic component using the material according to claim 1. 6. A Ni plating bath or a Ni alloy plating bath, electroplating is performed on a substrate having at least a surface made of Cu or Cu alloy, and then a Sn plating bath containing 0.2 to 10,000 ppm of Ag ions. Or S
A method for producing a material for electric / electronic parts, wherein electroplating is performed using an n-alloy plating bath. 7. The method for producing a material for electric / electronic parts according to claim 6, wherein said Sn plating bath or said Sn alloy plating bath contains 0.2 to 50 ppm of Cu ions. 8. The method according to claim 6, wherein the material after the second electroplating is subjected to a heat treatment or a reflow treatment.