JP2000054189A - MATERIAL FOR ELECTRIC AND ELECTRONIC PARTS USED BY BONDING WITH Sn-Bi-BASED SOLDER, ELECTRIC AND ELECTRONIC PARTS USING IT, ELECTRIC AND ELECTRONIC PARTS-MOUNTED SUBSTRATE, AND SOLDER BONDING, OR MOUNTING METHOD USING IT - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration with time in the strength of an Sn-Bi- based solder bonding part in a high temp. environment and to improve the bonding reliability therein by forming a pure Sn surface layer having a specified thickness on the surface of a substrate composed of Cu or a Cu alloy via an laminated intermediate layer of a Cu3Sn layer and a Cu6Sn5 layer. SOLUTION: On the surface of a substrate of the material for electric and electronic parts in which at least the surface is composed of Cu or a Cu alloy, and having a surface layer, preferably, contg. 0.2 to wt.% Cu, an intermediate layer 2 in which a Cu3Sn (ε phase) layer 2a and a Cu6Sn5 (η' phase) layer 2b are laminated in this order is formed. This intermediate layer 2 is formed by plating the surface of the base material 1 with Sn, next executing heat treatment and mutually diffusing Cu and Sn. Then, via this intermediate layer 2, a surface layer 3 composed of pure Sn, an Sn-Ag alloy or an Sn-Bi alloy having 1 to 20 μm thickness or of pure Ag having 1 to 10 μm thickness is formed by plating.

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, an electric / electronic part using the same, a substrate for mounting electric / electronic parts, and a solder joining method or a mounting method using the same. And electrical / electronic component materials that increase the joining reliability of the joint when soldered to a mating material using Sn-Bi solder, and electrical / electronic components and electrical / electronic component mounting boards using the same , And
The present invention relates to a solder joining method or a mounting method using the same.

[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 to 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.

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.

[0004] In the case of the above-mentioned materials, their surfaces are subjected to a surface treatment typified by plating to enhance the reliability of the material functions, and are actually used. For example, in the case of a lead material or a terminal material of a component used when mounting a component on a printed wiring board by soldering, a measure is taken to improve the solderability by applying Sn plating or Sn alloy plating to the surface thereof. . Specifically, after assembling the semiconductor 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 subjected to Sn plating or Sn-Pb
In some cases, alloy plating is performed, followed by reflow treatment by heating.

Further, in the case of a material made of Cu or Cu alloy, if the surface is plated with Sn or Sn alloy, the obtained material has excellent corrosion resistance and wear resistance in addition to the above-mentioned characteristics, and is economical. Because it is advantageous
In addition to the lead material, it is often used as a material for various terminals and connectors. By the way, when these materials are mounted on a printed wiring board, a hybrid IC board, or the like, it is customary to use a solder, which is an Sn-Pb alloy, with a counterpart material. However, Pb contained in the solder may adversely affect the human body. Therefore, in the future, the use of Pb, despite its excellent properties, will be avoided. And Pb
Alloys containing no Sn, specifically, Sn-Ag based, Sn
-Practical application of Zn-based, Sn-In-based, Sn-Bi-based and the like is being studied.

[0006] Of these, Sn-Ag type is excellent in bonding strength and wettability, but on the other hand, it has high melting point,
It is disadvantageous in that it is expensive, and although Sn-Zn-based ones are inexpensive, they have poor wettability and can be used only in a non-oxidizing atmosphere. Furthermore, the Sn-In type has a low melting point but is expensive.

[0007] The Sn-Bi system is inferior in heat resistance and has a problem in that it is brittle, but has an advantage that the melting point can be easily reduced and the cost can be reduced. In addition, since the Sn-Ag system, which is excellent in bonding strength and wettability but is difficult to have a high melting point, can be lowered in melting point by adding Bi, recently, There is a tendency that a Sn-based alloy containing Bi is put to practical use at an early stage.

Specifically, Sn-2% Bi-3% Ag,
Sn-5% Bi-3.25% Ag, Sn-4.8% Bi-
3.4% Ag, Sn-6% Bi-3% Ag, Sn-7.5
% Bi-2% Ag-0.5% Cu, Sn-9.5% Bi-
2.5% Ag, Sn-10% Bi-2.8% Ag-0.6
% Cu, Sn-22% Bi-2% Ag, Sn-0.5%
Bi-3.5% Ag-3% In, Sn-3% Bi-3.5
% Ag-3% In, Sn-6% Bi-6% Zn, Sn-
10% Bi-8% Zn, Sn-8% Bi-7% Zn, S
Materials such as n-14% Bi-5% Zn and Sn-58% Bi have been studied.

Hereinafter, Ag, Cu, Zn,
An Sn-based alloy solder containing an element other than Bi such as In is also referred to as a Sn-Bi-based solder. Thus, Sn-Bi
Although the system solder has such advantages that the melting point can be easily reduced and the price can be relatively reduced, it has the following problems. That is, when the solder joint is exposed to a high-temperature environment, the joint strength of the joint decreases greatly with time. In particular, when the Bi content is 2% by weight or more, when the molten solder is solidified, the segregation of Bi and the eutectic melting phenomenon of two or more elements containing Sn and Bi occur, and the low melting point portion is formed at the joint. This causes the strength of the joint to deteriorate, and in the worst case, cracks may occur at the joint.

[0010] This is disadvantageous in the following points. In other words, recently, high-density mounting of various components on printed wiring boards has been progressing,
The amount of heat radiation from the substrate is steadily increasing. Therefore, when the above-mentioned Sn-Bi solder is used at the time of mounting, the joint is always exposed to a high temperature state, so that the strength of the joint deteriorates with time, and during the actual operation of the device, A disconnection or short circuit accident may be caused. In other words, the joint using the Sn-Bi-based solder is inferior in joint reliability when exposed to a high-temperature environment.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a Sn-Bi
Solving the above-mentioned problems of the joints formed when using a system solder as a solder material for joining, the strength of the formed joints over time in a high-temperature environment is unlikely to decrease, and thus the joining of the joints An object of the present invention is to provide a material for an electric / electronic component that can enhance reliability, an electric / electronic component mounting board using the same, and a solder joining method using the same.

[0012]

In order to achieve the above object, according to the present invention, at least the surface of a substrate made of Cu or a Cu alloy has Cu ₃ Sn (ε
Phase) layer and a Cu ₆ Sn ₅ (η ′ phase) layer are stacked in this order through an intermediate layer to form a layer of pure Sn having a thickness of 1 to 20.
Sn, wherein a surface layer of μm is formed.
A material for electric / electronic parts (hereinafter referred to as a material A) used by bonding a Bi-based solder, and Cu ₃ Sn on the surface of a substrate having at least a surface made of Cu or a Cu alloy;
A 1-20 μm thick surface layer made of a Sn—Ag alloy is formed via an intermediate layer formed by laminating an (ε phase) layer and a Cu ₆ Sn ₅ (η ′ phase) layer in this order. A material for electric / electronic parts (hereinafter, referred to as a material B) used by joining Sn-Bi-based solder, at least the surface of which is made of Cu or a Cu alloy,
A surface layer of a Sn—Bi alloy having a thickness of 1 to 20 μm is formed via an intermediate layer formed by laminating a Cu ₃ Sn (ε phase) layer and a Cu ₆ Sn ₅ (η ′ phase) layer in this order. A material for electric / electronic parts (hereinafter, referred to as material C) which is used by joining Sn-Bi-based solder is provided.

Further, in the present invention, pure A is added to the surface of the substrate, at least the surface of which is made of Cu or a Cu alloy.
g, and a material for electric / electronic parts (hereinafter, referred to as material D) used by joining Sn-Bi-based solder, wherein a surface layer having a thickness of 1 to 10 μm is formed. The surface layer of each of the above-mentioned materials A to D contains 0.2 to 3% by weight of Cu, and is a material for electric / electronic parts used by joining Sn-Bi solders ( Hereinafter, referred to as material E).

In the present invention, the materials A to E
An electric / electronic component and an electric / electronic component mounting board characterized by using any one of the above are provided. Further, in the present invention, the material for electric / electronic parts of any of the above-mentioned materials A to E or the electric / electronic part using them is formed by using an Sn-Bi solder having a Bi content of 2% by weight or more. A solder joining or mounting method characterized by joining or mounting to a counterpart material or a circuit board is provided.

[0015]

FIG. 1 is a sectional view showing a layer structure of a material A, a material B and a material C of the present invention, and FIG. 2 is a sectional view showing a layer structure of a material D of the present invention. First, in the material shown in FIG. 1, a layer 2a made of Cu ₃ Sn (ε phase) and a layer 2b made of Cu ₆ Sn ₅ (η ′ phase) are laminated on the surface of the substrate 1 in this order. It has a layer structure in which a surface layer 3 described later is formed via the intermediate layer 2.

Here, the substrate 1 may be anything as long as at least its surface is formed of Cu or a Cu alloy, for example, Cu or Cu alloy itself, carbon steel, Fe--Ni Alloy, Fe-Ni-C
Fe-based materials such as o-based alloys and stainless steel
One whose surface is coated with Cu or a Cu alloy can be cited. In the case of the latter substrate, Cu or Cu alloy formed on the core material and its surface in consideration of the relationship between mechanical strength and conductivity required for the intended use of the part,
In particular, the type of Cu alloy is appropriately selected.

The shape of the substrate 1 is also appropriately selected, such as a linear shape, a plate shape, or a strip, in accordance with the purpose of use as a part or the surface layer forming method described later. In the case of the material A, the surface layer 3 is composed of pure Sn, in the case of the material B, the surface layer 3 is composed of an Sn-Ag alloy described later, and in the case of the material C
In this case, the surface layer 3 is made of a Sn—Bi alloy described later, and the thickness of the surface layer 3 is 1 to 20 μm in any of the materials A to C.

The material D shown in FIG. 2 has a layer structure in which the surface layer 3 made of pure Ag is directly formed on the surface of the substrate 1, and the thickness of the surface layer 3 is 1 to 10 μm. Is set to These surface layers 3 are formed by applying an electroplating method because the thickness control and the production control of the material are easy.

For example, in the case of materials A to C, a known Sn
Electroplating is performed by immersing the substrate in a plating bath or Sn alloy plating bath, and in the case of material D, a surface layer can be formed using a silver cyanide or potassium cyanide plating bath or a commercially available cyanide-free plating bath. it can. In addition, Sn-Ag alloy, S
When forming a surface layer of an n-Bi alloy, for example, Ag
Or Bi once plated on the surface of the substrate and then Sn
Plating can be performed, and subsequently, a heat treatment can be performed to form an alloy. If alloying is intended by the reverse method, surface unevenness and surface discoloration of the surface layer occur, which is not desirable.

When a surface layer is formed by plating Sn or a Sn alloy on the surface of the substrate 1 like the materials A, B, and C,
When heat treatment is further continued, mutual diffusion of Cu, which is the main component of the substrate surface, and Sn, which is the main component of the surface layer,
The intermediate layer 2 shown in FIG. 1 is formed at the interface between them, and the adhesion between the substrate 1 and the surface layer 3 is ensured. This middle layer 2
Has a laminated structure of a Cu ₃ Sn (ε phase) layer 2a located on the base 1 side and a Cu ₆ Sn ₅ (η ′ phase) layer 2b located on the surface layer 3 side.

These layers form a Cu-rich phase on the substrate surface side and contribute to ensuring adhesion to the substrate surface, and a Sn-rich phase on the surface layer side to improve adhesion to the surface layer. This contributes to the securing, and the two phases are mixed at the interface between the two layers 2a and 2b, so that the adhesion between the substrate surface and the surface layer is secured as a whole. However, material D
In the case of (1), the above-described mutual diffusion between the components is unlikely to occur between the substrate 1 and the surface layer 3 made of pure Ag, so that a two-layer structure as shown in FIG. 2 is obtained.

Here, in the materials A to C, if the thickness of the surface layer 3 is too thin, the interdiffusion of Cu and Sn progresses during the period from the formation of the surface layer to, for example, the mounting use, and Cu
_{The amount of 3} Sn (ε phase) and Cu ₆ Sn ₅ (η ′ phase) generated increases, which not only makes it difficult to secure wettability at the time of soldering using Sn—Bi solder, but also makes the material heat resistant. It is necessary that the thickness is 1 μm or more, since this causes a reduction in the properties. However, its thickness is 20 μm
Even if it is thicker, the performance will not only be saturated and wasted,
Unnecessarily, the production cost is increased, so the upper limit of the thickness is set to 20 μm.

In the case of the material D, the thickness of the surface layer 3 is 1
When the thickness is smaller than μm, when the period until actual use becomes long, oxidation of the substrate surface under the surface layer (pure Ag layer) proceeds, and copper oxide appears on the surface, which also reduces the solder wettability. Invite. On the other hand, if the thickness of the surface layer (pure Ag layer) is too large, the production cost increases, and the amount of Ag in the solder joint increases, and discoloration and corrosion due to sulfuration of the joint tend to occur. From such a thing,
The thickness of the surface layer (pure Ag layer) in the material D is 1 to 10 μm.
m.

Since the surface layer of the material A is made of pure Sn, when the material A is joined to a counterpart material using Sn-Bi solder, the Bi concentration in the formed joint is reduced. As a result, the heat resistance of the joint is improved. As a Sn-Ag alloy constituting the surface layer of the material B, the melting point of Sn-3.5% Ag having a eutectic composition is 2
Since the temperature is 21 ° C., those having an Ag content of about 3.5% by weight are preferred. Specifically, the Ag content is 1
-4% by weight.

Further, as the Sn—Ag alloy, Ag ₃ S
Those containing an n (ε phase) compound are preferred. This Ag ₃ Sn (ε phase) compound enhances the heat resistance including the creep characteristic of the surface layer, and at the same time, suppresses the interdiffusion between Sn, which is the main component of the surface layer, and Cu, which is the main component of the substrate surface. This is because they perform their functions. However, this Ag ₃ S
If the surface layer contains an n (ε phase) compound in an excessively large amount, the melting point is increased. Therefore, the content is preferably set to 5% by weight or less in terms of Ag.

Further, Sn-B constituting the surface layer of the material C
In the case of the i-alloy, the liquidus of the alloy decreases as the Bi content increases up to the eutectic composition of Sn-57% Bi. However, this means a decrease in heat resistance. On the other hand, if the Bi content exceeds 5% by weight, the bending workability of the material deteriorates, and cracks tend to occur. Further, the amount of Bi in the joint portion joined by using the Sn-Bi-based solder increases, which causes a decrease in heat resistance of the joint portion and a decrease in joint reliability in a high-temperature environment. For this reason, the content of Bi in the Sn—Bi alloy constituting the surface layer is preferably set to 1 to 10% by weight, particularly preferably 1 to 5% by weight.

In the case of the material C, since the solder used for joining is also a Sn-Bi solder, there is no problem with the heat resistance of the joint. Next, the material E will be described. This material E is a material in which Cu is added to the material constituting the surface layer in the materials A to D to further contain 0.2 to 3% by weight of the surface layer.

When this material E is solder-bonded to a counterpart material using Sn-Bi solder or mounted on a circuit board (solder-bonded to the board electrode portion), compared to the materials A to D Thus, the effect that the joining reliability in the high temperature environment of the joining portion is further improved is exhibited. This is because, since Cu is contained in the surface layer, heat resistance including creep characteristics of the surface layer is improved, and S which is a main component of the surface layer is improved.
This is because alloying based on interdiffusion between n or Ag and Cu or another constituent element that is a main component of the substrate surface is suppressed, and deterioration with time of the bonded portion in a high-temperature environment becomes difficult to progress.

However, the Cu content is 0.2% by weight.
When the amount is less than the above, the above-mentioned effect is not exhibited. When the amount is more than 3% by weight, when the surface layer is a pure Sn layer or an Sn alloy layer, its liquidus line becomes excessively high, for example, during a reflow treatment. Non-uniform solidification bonding occurs at the time of wave soldering, and furthermore, Cu oxidation of the surface occurs, which tends to cause a decrease in solder wettability and a decrease in corrosion resistance. For these reasons, the Cu content is set to 0.2 to 3% by weight.

When Cu is contained in the surface layer, the plating bath used for forming the surface layer may further contain a predetermined amount of Cu ions, and electroplating may be performed. Usually, if the plating bath contains about 0.2 to 50 ppm of Cu ions, the Cu content in the surface layer can be set to the above-mentioned value. In the case of the material of the present invention, the surface layer is a pure Sn layer (for material A), an Sn-Ag alloy layer (for material B), and a Sn-Bi alloy layer (for material C) as described above. , Pure Ag layer (in the case of material D) may be formed alone, but these Sn, Sn-Ag alloy, Sn-B
Two types may be appropriately selected from i-alloy and Ag, and these may be used to form a surface layer having a two-layer structure. In that case, the reliability of the joint in a high-temperature environment may be improved as compared with the case where the joint is used alone.

Further, the material of the present invention, after forming a layer structure by the plating method as described above, is further subjected to a reflow treatment in a non-oxidizing atmosphere or a reducing atmosphere, for example, the formation of whiskers in the surface layer. In addition to being able to suppress, the diffusibility of each component in the surface layer is also reduced, so that the overall heat resistance can be improved and the reliability of the joint can be increased.

The electric / electronic component of the present invention uses any one of the above-mentioned materials A to E.
For example, the electrodes and lands are formed of the above-mentioned materials. Further, the electric / electronic component mounting board of the present invention is manufactured by manufacturing various electric / electronic components using any of the above-mentioned materials A to E and mounting them.

The solder joining method of the present invention is used as a joining solder material when any one of the above-mentioned materials A to E or an electric / electronic component using them and a mating material or a circuit board are joined by soldering. It is characterized by using a Sn-based alloy solder having a Bi content of 2% by weight or more. Therefore, the solder joint of the present invention is in a Pb-free state,
As described above, the bonding reliability of the bonding portion is high.

From the above, according to the solder bonding method of the present invention, it is possible to put into practical use an electric / electronic component mounting board for use in a high-temperature environment in recent years and in the future.

[0035]

EXAMPLES Examples 1 to 12 and Comparative Examples 1 to 4 A Cu-coated steel wire having a wire diameter of 0.5 mm was sequentially moved to a cathode degreasing tank, an acid pickling tank, and a plating tank. Was manufactured as a surface layer.

Of each surface layer, a pure Sn layer and Cu ₃ Sn
The anodic dissolution method is applied to the (ε phase) layer and the Cu ₆ Sn ₅ (η ′ phase) layer, and the fluorescent X Each thickness was measured with a line. The composition of the surface layer was quantitatively analyzed by a ZAF correction method using an electron beam microanalyzer.
The presence or absence of a Cu ₃ Sn (ε phase) layer and a Cu ₆ Sn ₅ (η ′ phase) layer at the interface between the Cu-coated steel wire and the surface layer was observed by a line diffraction method. The results are shown in Table 1.

Each lead wire was subjected to a heat treatment in the air at 150 ° C. for 50 hours, and then the solder wettability was measured by a wetting balance method. The measurement of solder wettability was performed using a dynamic wetting tester manufactured by Resca Co., Ltd., and a Sn-38% Pb eutectic solder maintained at 230 ° C. was used as a solder, and an RMA type flux was used as a flux. The immersion depth was 2 mm, the immersion speed was 10 mm / sec, and the wetting time (zero cross time) was measured. The measured values before and after the above-mentioned heating are shown in Table 1.

[0038]

[Table 1]

In general, it is desirable that the solder zero crossing time is 1 second or less. Considering this, Cu is required in the process from immediately after formation of the surface layer to actual use.
Considering the growth of ₃ Sn (ε phase) and Cu ₆ Sn ₅ (η ′ phase) and the occurrence of surface oxidation, as is clear from Table 1, the thickness of the surface layer should be 1 μm or more. The upper limit of the thickness is 2
It is sufficient to set it to 0 μm.

Examples 13 to 26, Comparative Examples 5 to 12 A 0.4 mm thick tough pitch copper plate was subjected to cathodic degreasing and pickling treatments, followed by a first plating bath and a second plating bath shown in Table 2.
Plating was sequentially performed in the plating bath and the third plating bath to form a plating layer having a layer structure shown in Table 2. In addition,
A case in which Cu ions were contained in the plating bath was also implemented, and a part of the obtained material was subjected to a reflow treatment under the conditions shown in Table 2.

The composition and thickness of the surface layer were measured by applying a quantitative analysis by a ZAF correction method using an electron beam microanalyzer and X-ray fluorescence measurement. In addition, from the surface layer formed by plating the Sn—Ag alloy, Ag ₃ Sn
(Ε phase) Compound was detected. Table 2 to Table 4 show the above results.
It was shown to.

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

Each of the obtained materials was cut into a 25 mm square, and a Cu-coated steel wire having a diameter of 3 mm was joined to the sample with various solders. At this time, the used solder had the following composition. The size of the solder joint is 6 m in diameter.
m. Solder 1: Sn-2% Bi-3.5% Ag-3% In, Solder 2: Sn-7.5% Bi-2% Ag-0.75% C
u, Solder 3: Sn-57% Bi, Solder 4: Sn-1% Bi-3% Ag, Solder 5: Sn-3.5% Ag, Solder 6: Sn-38% Pb (eutectic).

Next, the bonding strength (T ₀ : N / mm ² ) between each sample and the Cu-coated steel wire was measured at room temperature. Then, the solder bonding material is subjected to a temperature of 150 in air.
Subjected to the degradation promotion treatment at the temperature shown in Tables 5 to 12,
At that time, the bonding strength between each sample and the Cu-coated steel wire (T ₁ :
N / mm ² ), and (T ₀ −T ₁ ) × 100 / T ₀ was calculated to determine the deterioration rate (%) of the solder joint.

The results when solder 1, solder 2, and solder 3 were used are collectively shown in Tables 5 to 8, and the results when solder 4, solder 5, and solder 6 were used are shown in Tables 9 to 12. Indicated. In consideration of the strength and the deterioration rate, an outline evaluation of the joint reliability is also shown. In the table, circles indicate 1) T ₀ is 15 N / mm ^2.
Is greater than 40% and the degradation rate after the degradation promotion treatment at 150 ° C. for 1000 hours is less than 40%, or 2) T ₀ is 20 N / m.
m ² and the degradation rate after the degradation promotion treatment at 150 ° C. for 1000 hours is less than 50%, or 3) T ₀
Is greater than 25 N / mm ² and the rate of deterioration after the deterioration promotion treatment at 150 ° C. for 1000 hours is less than 55%. The subsequent strength is 10 N / mm ² or more and does not correspond to the above-mentioned ○ mark.
The case where the strength after the deterioration promotion treatment for 000 hours is less than 10 N / mm ² is shown.

[0048]

[Table 5]

[0049]

[Table 6]

[0050]

[Table 7]

[0051]

[Table 8]

[0052]

[Table 9]

[0053]

[Table 10]

[0054]

[Table 11]

[0055]

[Table 12]

As is clear from Tables 5 to 12, all of the materials of the present invention can be obtained by using a Sn-Bi solder having a Bi content of 2% by weight or more when soldered to a mating material. Even if the joint is exposed to a high-temperature environment for a long time, the rate of deterioration of the joint strength of the joint is small and a highly reliable joint can be formed. In particular, in the case of a material in which Cu is contained in the surface layer or a material in which the surface layer is formed of an alloy layer having a two-layer structure, the reliability of the joint when Sn-Bi solder is used is further improved. I have.

[0057]

As is clear from the above description, the material of the present invention and the electric / electronic parts using the same have a Bi content of 2 which has begun to be used as a Pb-free solder.
When bonded to a counterpart material with Sn-based alloy solder of not less than weight%, or when mounted on a circuit board or the like, the bonding reliability of the bonded portion in a high temperature environment can be ensured.

Therefore, by manufacturing various electric / electronic parts using the material of the present invention and mounting them on a substrate, various electric / electronic parts mounting boards used under a high temperature environment without environmental pollution can be obtained. It can be manufactured and its industrial value is great.

[Brief description of the drawings]

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

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

[Explanation of symbols]

REFERENCE SIGNS LIST 1 base 2 intermediate layer 2a Cu ₃ Sn (ε phase) layer 2b Cu ₆ Sn ₅ (η ′ phase) layer 3 surface layer

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hitoshi Tanaka 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 4K024 AA07 AA10 AA15 AA16 AA21 AB01 AB04 BA09 BB09 BB11 DB01 GA01 4K044 AA06 AB10 BA10 BB01 BB05 BC05 BC08 CA18 CA62

Claims (8)

[Claims] 1. A method according to claim 1, wherein a Cu ₃ Sn (ε phase) layer and a Cu ₆
A Sn—Bi-based solder, wherein a surface layer made of pure Sn and having a thickness of 1 to 20 μm is formed via an intermediate layer formed by laminating a Sn ₅ (η ′ phase) layer in this order. For electrical and electronic parts used by bonding 2. A Cu ₃ Sn (ε phase) layer and a Cu ₆ Sn
Via an intermediate layer and a Sn ₅ (η 'phase) layer formed by laminating in this order, wherein the surface layer of 1~20μm thickness consisting of Sn-Ag alloy is formed, Sn-Bi
Materials for electric and electronic parts used by joining series solder. 3. A Cu ₃ Sn (ε phase) layer and a Cu ₆ Sn
A Sn-Bi alloy, wherein a surface layer made of a Sn-Bi alloy and having a thickness of 1 to 20 µm is formed via an intermediate layer formed by laminating a Sn ₅ (η 'phase) layer in this order.
Materials for electric and electronic parts used by joining series solder. 4. A substrate having at least a surface made of Cu or a Cu alloy and having a thickness of 1 to 10
Sn, wherein a surface layer of μm is formed.
-Materials for electric and electronic parts used by joining Bi-based solder. 5. The Sn—Bi solder according to claim 1, wherein the surface layer of the electric / electronic component material according to claim 1 contains 0.2 to 3% by weight of Cu. Used for electrical and electronic parts. 6. An electric / electronic component using the electric / electronic component material according to claim 1. 7. An electric / electronic component mounting board, wherein the electric / electronic component material according to claim 1 is used. 8. The electric / electronic component material according to claim 1 or an electric / electronic component using them,
A solder joining or mounting method characterized by joining or mounting to a counterpart material or a circuit board using a Sn-Bi-based solder having a content of 2% by weight or more.