JPH1143731A - High strength copper alloy excellent in stamping property and suitable for silver plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a Gu-Ni-Si type high strength copper alloy excellent in silver plating suitableness as well as in stamping property. SOLUTION: This high strength copper alloy has a composition which consists of, by weight, 0.4-4.0% Ni, 0.05-1.0% Si, 0.001-5% Sn, 0.1-5.0% Zn, 0.005-1.0% Mg, 0.0003-0.005% S, 0.0003-0.01% C, and the balance Cu with inevitable impurities and in which respective contents of Mg and S simultaneously satisfy the following (1) and (2): (1) -0.5[Mg]+0.005<= [S]; (2) [S] <=0.25[Mg]. In the above inequalities, [Mg] and [S] represent respective weight percentages of Mg and S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric / electronic device such as a semiconductor lead frame, a terminal, a connector, a relay, and a switch.
The present invention relates to a high-strength copper alloy having excellent stamping workability and silver plating property used for electronic components.

[0002]

2. Description of the Related Art Cu-Ni-Si-based copper alloys are widely used in electric and electronic parts such as semiconductor lead frames, terminals, connectors, etc. because they have both strength and electrical conductivity. 2. Description of the Related Art In recent years, as electric and electronic components have become smaller, lighter, and more highly integrated, the lead interval of a lead frame or the pitch between connectors has been reduced. As a result, not only demands for high strength and high conductivity, but also a demand for a material that is excellent in stamping workability (reducing burrs and drooping after stamping work) and that does not wear the stamping die are increasing (for example, And JP-A-2-66130. In addition, these electric / electronic parts are sometimes plated with silver, but due to an increasing demand for improvement in reliability, silver plating is becoming more important than ever (for example, JP-A-63-130739,
JP-A-5-59468, JP-A-8-319528
Reference).

[0003]

SUMMARY OF THE INVENTION Cu for electric / electronic parts
In a -Ni-Si-based copper alloy, Mg is used as an additive element for suppressing a decrease in conductivity and improving strength. As described in Japanese Patent Application Laid-Open No. 2-66130, Mg is highly effective in reducing stamping workability and mold abrasion. (Protrusions) are known. An object of the present invention is to provide a Cu-Ni-Si-based high-strength copper alloy containing Mg in which both the stamping workability and the silver plating property, which were conventionally considered to be contradictory, are compatible.

[0004]

According to the present invention, a high-strength copper alloy excellent in stamping workability and silver plating property is Ni:
0.4 to 4.0 wt%, Si: 0.05 to 1.0 wt%
%, Sn: 0.001 to 5.0 wt%, Zn: 0.1 to
5.0 wt%, Mg: 0.005 to 1.0 wt%, S:
0.0003-0.005 wt%, C: 0.0003-
It is characterized by containing 0.01 wt%, the balance being Cu and unavoidable impurities, and the contents of Mg and S satisfy the following expressions (1) and (2) simultaneously. 0.5 [Mg] + [S] ≧ 0.005 (1) 0.25 [Mg] ≧ [S] (2)

The above-mentioned copper alloy has Be, B,
Al, P, Ti, V, Cr, Mn, Fe, Co, Pb,
Ca, Zr, Nb, Mo, Ag, In, Sb, Hf, T
a in total of 0.001 to 1.0
wt%. Further, the average crystal grain size in the thickness direction is preferably 20 μm or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The components of the copper alloy according to the present invention and the reasons for limiting the crystal grain size will be described below. (Ni) By adding Ni together with Si, Ni
And an element having a function of improving the strength of the alloy by generating a compound of Si and Si. However, if the content is less than 0.4 wt%, this effect is small, and if the content exceeds 4.0 wt%, the hot workability and the cold workability deteriorate, which is not preferable. Therefore, the content of Ni is set to 0.4 to 4.0 wt%.

(Si) Si is an element which, when added together with Ni, produces a compound of Ni and Si and has the effect of improving the strength of the alloy. However, 0.05w
If it is less than t%, this effect is small, and if it exceeds 1.0 wt%, hot workability and cold workability deteriorate, which is not preferable. Therefore, the content of Si is 0.05 to
1.0 wt%.

(Sn) Sn is an element that improves strength, spring characteristics and stress relaxation resistance. However, 0.001
If the content is less than wt%, the effect is small, and if the content exceeds 5.0 wt%, the effect is saturated, and the hot workability is deteriorated and the conductivity is lowered.

(Zn) Zn is an element that improves the heat-peeling resistance of tin and tin alloy plating, and also improves the migration resistance. However, if the content is less than 0.1% by weight, these effects are small, and if the content exceeds 5.0% by weight, the effect is saturated, and the conductivity is lowered and the sensitivity to stress corrosion cracking is increased, which is not preferable. Therefore, Zn
Is 0.1 to 5.0 wt%.

(Mg) Mg is an element that improves strength, stress relaxation resistance and stamping workability, and is also effective in reducing mold wear. If the content is less than 0.005% by weight, the effect is small, and if the content exceeds 1.0% by weight, the effect is saturated and the castability, the hot workability is deteriorated, and the electrical conductivity is lowered. Therefore, the content of Mg is set to 0.005 to 1.0 wt%.
Further, Mg also participates in silver plating properties through interaction with S as described below.

(S) S improves the stamping workability together with Mg, but is also an element that easily causes silver projections during silver plating. If less than 0.0003 wt%, the effect of improving the stamping workability is small, and 0.005 w
When the content exceeds t%, silver plating property and hot workability are deteriorated. Therefore, the content of S is 0.0003 to 0.0.
05 wt%.

(Relationship between Mg and S) Cu containing Mg
The present inventors have found that it is necessary to limit both components to the following ranges in order to achieve both stamping workability and silver plating property in a -Ni-Si-based high-strength copper alloy. First, from the viewpoint of stamping workability, it is desirable that Mg and S are large, and it is necessary that at least the following expression (1) is satisfied. 0.5 [Mg] + [S] ≧ 0.005 (1)

Next, from the aspect of silver plating properties, it is necessary to control the ratio in the following manner. That is, the main cause of silver protrusion is Mg formed by combining Mg and S.
S, which is localized in the copper alloy,
This is because the local potential of that portion becomes low, and local precipitation of silver occurs. However, if the content of Mg is sufficiently large, Mg which forms a solid solution in the copper will be mixed with the matrix of the copper alloy and
Since the potential difference with gS is reduced, local precipitation of silver is less likely to occur. Therefore, it is desirable that Mg is large in proportion to S, and it is necessary to satisfy at least the following expression (2). 0.25 [Mg] ≧ [S] (2)

(C) C is Mg-containing Cu-Ni-S
The present inventors have found that the i-type copper alloy has an effect of improving the stamping workability. However, 0.000
If the content is less than 3 wt%, the effect is small. If the content exceeds 0.01 wt%, the effect is saturated and the hot workability is deteriorated. Therefore, the content of C is 0.00
03 to 0.01 wt%, preferably 0.001 to 0.0
1 wt%.

(Subcomponents) Be, B, Al, P, Ti,
V, Cr, Mn, Fe, Co, Pb, Ca, Zr, N
The subcomponents of b, Mo, Ag, In, Sb, Hf, and Ta are as follows:
In order to further improve strength and stamping workability,
It is an element that can be added within a range where a decrease in conductivity is allowed. When the total amount of one or more of these elements is less than 0.001 wt%, the effect of improving strength is small and 1 w
If the content exceeds t%, the electrical conductivity significantly decreases, which is not preferable. Therefore, the total amount of these subcomponents is set to 0.1.
001 to 1 wt%.

(Grain size) Cu-Ni- containing Mg
The present inventors have found that, in a Si-based copper alloy, particularly, the crystal grain size in the thickness direction contributes to stamping workability. The average crystal grain size in the sheet thickness direction in the final sheet product state is 20
If it is not more than μm, the stamping workability can be improved. It is desirably 15 μm or less. Even if the crystal grain size exceeds 20 μm in the recrystallization stage, the case where the crystal grain becomes flat due to the subsequent cold working and the average crystal grain size in the plate thickness direction becomes 20 μm or less is included in this.
In the case of a so-called fiber structure, which is observed in a material which has been subjected to a cold working of 90% or more after recrystallization, crystal grains are difficult to observe, but such a fiber structure is also included in the present invention.

[0017]

EXAMPLES Examples of high-strength copper alloys having excellent stamping workability and silver plating properties according to the present invention will be described below along with comparative examples. A copper alloy having a component composition shown in Tables 1 to 4 was melted in the air under a charcoal coating in a kryptor furnace, cast into a book mold, and 50 mm × 80 mm × 200 m.
m was produced. This ingot was heated to 930 ° C., hot-rolled, and immediately quenched in water to obtain a hot-rolled material having a thickness of 15 mm. In order to remove the oxide scale on the surface of this hot rolled material,
The surface was cut with a grinder. The hot-rolled material was cold-rolled to a thickness of 0.36 mm, heat-treated at 650 to 850 ° C. for 20 seconds, and then rapidly cooled in water. Further, cold-rolled to a thickness of 0.25 mm, annealed at 450 to 500 ° C. for 2 hours,
After removing the oxide film on the surface by pickling, it was subjected to a test.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

With respect to this test material, tensile strength, electrical conductivity, crystal grain size, stamping workability, silver plating property, and solder heat resistance peeling property were examined in the following manner. Tables 5 and 6 show these results. For the tensile strength, a JIS No. 5 test piece was used. The conductivity was measured by the double bridge method. The crystal grain size was measured in the plate thickness direction by a cutting method of a copper grain size grain size test method specified in JIS H0501. The stamping workability was evaluated by pressing using a press with a length of 30 mm and a width of 0.1 mm.
A 5 mm lead was punched out, and the height of the burrs was measured. The silver plating property was observed by a stereoscopic microscope for the presence or absence of a phenomenon (projection) where the plating thickness was locally increased when cyanic silver plating was applied at a thickness of 1 μm. Solder heat peel resistance is 245
The material coated with a plating layer of about 20 μm by dipping in a solder bath (60 Sn / 40 Pb) at
After heating for 00 hours, the plate was bent 180 ° and returned to a flat plate, and then the presence or absence of peeling of the solder plating layer was observed.

[0023]

[Table 5]

[0024]

[Table 6]

As shown in Table 5, the alloy No. of the present invention. 1 to
No. 22 has good characteristics. On the other hand, as shown in Table 6, Comparative Alloy No. 23 to 43 are inferior in any of the properties because some components are out of the range specified in the present invention. In addition, No. In Nos. 42 and 43, although the contents of Mg and S are included in the range specified in the present invention, they are out of the range of the formula (1) or the formula (2), so that silver plating property or stamping workability is inferior.

Also, in Table 1, No. About alloy 2
In order to see the effect of the crystal grain size, the temperature of the intermediate heat treatment for 20 seconds was changed.
o. 2) and the same test as above. Table 7 shows the results. As shown in Table 7, the temperature of the heat treatment for 20 seconds was so low that no recrystallization occurred. 2-2 is a fiber structure. Almost the same characteristics as those of No. 2 were obtained, but the heat treatment temperature was high. In No. 2-3, the average crystal grain size is large, and the stamping workability is No. 2; It is lower than 2.

[0027]

[Table 7]

[0028]

The copper alloy of the present invention satisfies the characteristics required for electric and electronic parts, such as strength, electrical conductivity, and heat-peeling resistance of solder, as well as, for example, lead frames, terminals and connectors of semiconductor devices. When the electric / electronic part is stamped, the burring height is small, so that the dimensional accuracy and the service life of the punching die can be remarkably improved. In addition, it is possible to suppress the occurrence of silver protrusion when silver plating is performed. Therefore, the present invention greatly contributes to improvement in productivity and reliability of electric / electronic parts.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yosuke Miwa 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside of Kobe Steel's Chofu Works (72) Inventor Masaaki Isono 141-1, Nagafuminatomachi, Shimonoseki City, Yamaguchi Prefecture Kobe Steel, Ltd.

Claims (4)

[Claims] 1. Ni: 0.4 to 4.0 wt%, Si:
0.05 to 1.0 wt%, Sn: 0.001 to 5.0 w
t%, Zn: 0.1 to 5.0 wt%, Mg: 0.005
~ 1.0wt%, S: 0.0003 ~ 0.005wt
%, C: 0.0003 to 0.01 wt%, the balance being Cu and unavoidable impurities, and the contents of Mg and S satisfy the following formulas (1) and (2) simultaneously. High strength copper alloy with excellent workability and silver plating properties. 0.5 [Mg] + [S] ≧ 0.005 (1) 0.25 [Mg] ≧ [S] (2) ([Mg] is wt% of Mg, [S ] Means wt% of S, the same applies hereinafter) 2. Ni: 0.4 to 4.0 wt%, Si:
0.05 to 1.0 wt%, Sn: 0.001 to 5.0 w
t%, Zn: 0.1 to 5.0 wt%, Mg: 0.005
~ 1.0wt%, S: 0.0003 ~ 0.005wt
%, C: 0.0003 to 0.01 wt%, the balance consisting of Cu and unavoidable impurities, and the contents of Mg and S simultaneously satisfy the following formulas (1) and (2).
A high-strength copper alloy having excellent stamping workability and silver plating properties, wherein the average crystal grain size in the thickness direction is 20 μm or less. 0.5 [Mg] + [S] ≧ 0.005 (1) 0.25 [Mg] ≧ [S] (2) 3. Ni: 0.4 to 4.0 wt%, Si:
0.05 to 1.0 wt%, Sn: 0.001 to 5.0 w
t%, Zn: 0.1 to 5.0 wt%, Mg: 0.005
~ 1.0wt%, S: 0.0003 ~ 0.005wt
%, C: 0.0003-0.01 wt%, and Be, B, Al, P, Ti, V, Cr, Mn,
Fe, Co, Pb, Ca, Zr, Nb, Mo, Ag, I
One or more of n, Sb, Hf, and Ta are contained in a total amount of 0.001 to 1.0 wt%, and the balance is made up of Cu and unavoidable impurities. Further, Mg and S are represented by the following formulas (1) and (2). ) Is a high-strength copper alloy that is excellent in stamping workability and silver plating, characterized by simultaneously satisfying (2). 0.5 [Mg] + [S] ≧ 0.005 (1) 0.25 [Mg] ≧ [S] (2) 4. Ni: 0.4 to 4.0 wt%, Si:
0.05 to 1.0 wt%, Sn: 0.001 to 5.0 w
t%, Zn: 0.1 to 5.0 wt%, Mg: 0.005
~ 1.0wt%, S: 0.0003 ~ 0.005wt
%, C: 0.0003-0.01 wt%, and Be, B, Al, P, Ti, V, Cr, Mn,
Fe, Co, Pb, Ca, Zr, Nb, Mo, Ag, I
One or more of n, Sb, Hf, and Ta are contained in a total amount of 0.001 to 1.0 wt%, and the balance is made up of Cu and unavoidable impurities. Further, Mg and S are represented by the following formulas (1) and (2). A) a high-strength copper alloy excellent in stamping workability and silver plating property, wherein the average grain size in the thickness direction is 20 μm or less. 0.5 [Mg] + [S] ≧ 0.005 (1) 0.25 [Mg] ≧ [S] (2)