JP2004315940A - Cu-Ni-Si ALLOY AND ITS PRODUCTION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Cu-Ni-Si alloy for an electronic material in which high strength and high electrical conductivity are made compatible. <P>SOLUTION: In the Cu-Ni-Si alloy having a composition comprising, by mass, 1.0 to 4.5% Ni and 0.25 to 1.5% Si, and the balance Cu with inevitable impurities, provided that each mass concentration of Ni and Si is defined as [Ni] and [Si], the mass concentration ratio between Ni and Si, [Ni]/[Si] is 4 to 6, and also, χ defined by formula (1) is 0.1 to 0.45: ([Ni]-4χ)<SP>2</SP>([Si]-χ)=1/8 (formula 1). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１９】
次に厚さ９ｍｍまで熱間圧延を行い、表面スケール除去の為面削を施した後、冷間圧延により厚さ１ｍｍの板とした。その後、７５０℃〜８５０℃の温度で溶体化処理を行った後、厚さ０．４ｍｍまで冷間圧延した。そして各合金の組成につき、引張強さが最大となる温度で３時間の時効処理を行った。この温度は４００〜６００℃の範囲であった。更に、冷間圧延で厚さ０．２５ｍｍの板とした。最終熱処理後の試料の強度は、引張試験機において引張強さにより評価した。導電性は四端子法にて導電率（％ＩＡＣＳ）により評価した。また、［Ｎｉ］／［Ｓｉ］およびχの値が、請求項１の範囲内を（○）、範囲外を（×）として評価した。表１に結果を示す。
【００２０】
表１から分かるように発明例Ｎｏ．１〜Ｎｏ．１３は［Ｎｉ］／［Ｓｉ］およびχの値を全てが請求項１の範囲内である。従って、発明例は、引張強さで７２０ＭＰａ以上、導電率で４５％ＩＡＣＳ以上であり、高強度、高導電性を有している。
さらに応力緩和特性を改善するためにＭｇを添加した発明例Ｎｏ．２、４、６、７、８でも、Ｍｇを添加しないものと同様に、高い強度と導電率が得られている。
また、Ｚｎ、Ｓｎ、Ｆｅ、Ｔｉ、Ｚｒ、Ｃｒ、Ａｌ、Ｐ、Ｍｎ、Ａｇ、またはＢｅのうち１種類以上を総量で０．００５〜２．０％添加した発明例Ｎｏ．７〜１３は添加されていない発明例Ｎｏ．１〜６に比べて導電性はやや劣るものの、強度の面では優れている。
【００２１】
一方、比較例を見ると、Ｎｏ．１４及び１６は、χの値が０．４５より高いため、強度はそれほど増加せず、導電率が低くなった。これは、強度に寄与しない粗大なＮｉ−Ｓｉ系粒子（晶出物及び析出物）が生成するためである。Ｎｏ．１５は、高い導電率を示したが、析出量を意味するχの値が低いため、強度が低くなった。Ｎｏ．１７は、［Ｎｉ］／［Ｓｉ］が低く、Ｓｉ過剰となり導電率が低くなった。Ｎｏ．１８は、［Ｎｉ］／［Ｓｉ］が高く、固溶Ｎｉが多く、導電率が低くなった。Ｎｏ．１９は、χの値が高く、更に［Ｎｉ］／［Ｓｉ］が低いので、導電率が著しく低下した。
Ｎｏ．２０は、Ｍｇの添加量が多すぎるため、熱間圧延での加工性が悪く、割れが発生し、後工程を進めることができなかった。
Ｎｏ．２１〜２３では、Ｚｎ、Ｓｎ、Ｆｅ、Ｔｉ、Ｚｒ、Ｃｒ、Ａｌ、Ｐ、Ｍｎ、Ａｇ、またはＢｅのうち１種類以上の元素が添加された時の総量が２．０％を超えているため、導電率が著しく悪かった。
【００２２】
【発明の効果】
以上説明した通り、本発明合金は、優れた強度と導電性を有しており、リードフレーム、端子、コネクターなどの電子材料用銅合金として好適である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a Cu—Ni—Si alloy used for manufacturing electronic components such as electronic materials having excellent strength and conductivity.
[0002]
[Prior art]
Copper alloys used for lead frames, various terminals of electronic devices, connectors, and the like are required to have both high strength and high conductivity. Furthermore, in recent years, in lead frames, various terminals of electronic devices, connectors, and the like, the number of leads and the like have been increased and the pitch has been narrowed, and high-density mountability and high reliability of electronic components have been required. Also in these materials used for electronic parts, required characteristics such as thinning, good workability, and high conductivity are becoming increasingly severe.
[0003]
Materials used for lead frames, various terminals of electronic equipment, connectors, etc. require high strength and high conductivity, and instead of conventional solid solution strengthened alloys such as phosphor bronze and brass, electronic equipment From the viewpoints of weight reduction, high strength, and high conductivity of components, the use of age hardening type copper alloys is increasing. Age-hardened copper alloys are prepared by subjecting a solution-treated supersaturated solid solution to aging, whereby fine particles are uniformly deposited and mechanical properties such as tensile strength, proof stress, and spring limit are improved. The amount of solid solution elements therein decreases and the conductivity improves.
[0004]
Among the age hardening type copper alloys, Cu-Ni-Si alloy is a typical copper alloy having both high strength and high conductivity. This copper alloy has excellent strength and conductivity due to precipitation of fine Ni-Si-based intermetallic compound particles, and has been put to practical use as a material for lead frames, various terminals of electronic devices, connectors, and the like (for example, Patent Document 1). reference.).
[0005]
[Patent Document 1]
Japanese Patent Application No. 2000-018319
[0006]
[Problems to be solved by the invention]
The strength and conductivity of the Cu-Ni-Si alloy are improved by precipitation of Ni-Si-based intermetallic compound particles. However, in general, the strength and the conductivity of an alloy have an opposite relationship, and the higher the strength, the lower the conductivity, and the higher the conductivity, the lower the strength. In the case of a Cu-Ni-Si alloy, if the added Ni and Si are made to have a low concentration, the amount of solid solution elements which do not form precipitates of Ni-Si based intermetallic compound particles is reduced and sufficient conductivity is obtained, but the low concentration is obtained. Therefore, the amount of precipitation decreases and the strength becomes insufficient. On the other hand, when the concentration is increased, the amount of precipitation increases and sufficient strength can be obtained, but there is a problem that the amount of solid solution elements that do not form precipitates of the Ni-Si intermetallic compound particles increases and the conductivity becomes insufficient. Was.
The present invention has been made to solve the above-described problems, and has as its object to provide a Cu—Ni—Si alloy for electronic materials that has both high strength and high conductivity.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present inventors have repeatedly studied a Cu-Ni-Si alloy, and have succeeded in developing a Cu-Ni-Si alloy having both high strength and high conductivity.
[0008]
That is, the present invention
(1) A copper-based alloy containing 1.0 to 4.5% Ni and 0.25 to 1.5% Si, with the balance being Cu and unavoidable impurities, and the mass concentration of Ni and Si is [Ni ], [Ni] / [Si] of Ni and Si when [Si] is 4 to 6, and ６ defined by (Equation 1) is 0.1 to 0.45. Ni] and [Si], a Cu—Ni—Si alloy having both high strength and high conductivity,
([Ni] -4χ) ² ([Si] -χ) = 1/8 (Equation 1)
(2) The Cu-Ni-Si alloy according to (1), wherein the Cu-Ni-Si alloy contains 0.05 to 0.3% of Mg.
(3) The above-mentioned (1) is characterized in that it contains at least one of Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, and Be in a total amount of 0.005 to 2.0%. A Cu-Ni-Si alloy according to 1) or (2).
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the reason why the composition range of the copper alloy is limited as described above in the present invention will be specifically described.
Ni and Si concentrations Ni and Si are subjected to an aging treatment, and Ni and Si form fine intermetallic compound precipitate particles mainly composed of Ni ₂ Si, thereby significantly increasing the strength of the alloy and at the same time, increasing the conductivity. Highly improve. However, if the Ni concentration is less than 1.0% or the Si concentration is less than 0.25%, the desired strength cannot be obtained even if the other component is added. When the Ni concentration exceeds 4.5% or when the Si concentration exceeds 1.5%, sufficient strength is obtained, but the conductivity is lowered and coarse Ni that does not contribute to improvement in strength is obtained. -Si-based particles (crystals and precipitates) are generated in the matrix, which causes deterioration in bending workability, etching properties, and plating properties. Therefore, the Ni concentration was set to 1.0 to 4.5%, and the Si concentration was set to 0.25 to 1.5%.
[0010]
[ Ni ] / [ Si ] mass concentration ratio As the amount of solid solution Ni and the amount of solid solution Si in the alloy decrease, the conductivity increases. When an aging treatment is applied to a Cu—Ni—Si alloy, Ni ₂ Si precipitates and the amount of solid-solution Ni and the amount of solid-solution Si decrease, thereby improving the conductivity. The amount of solid solution Ni and the amount of solid solution Si after aging increase and decrease according to the relationship between solubility products (formula 1) described later. For example, when the ratio of the Ni concentration and the Si concentration ([Ni] / [Si]) in the alloy increases, the amount of solid solution Ni increases and the amount of solid solution Si decreases. On the other hand, when comparing the degree of influence on the decrease in conductivity, the amount of solid solution Si is much larger than the amount of solid solution Ni. Therefore, [Ni] / [Si] that gives the maximum conductivity does not match the Ni / Si ratio (= 4.18) in the precipitate Ni ₂ Si.
[0011]
The present inventors examined the relationship between [Ni] / [Si] and the power transmission rate by experiments, and adjusted [Ni] / [Si] to a range of 4 to 6 in order to obtain high conductivity. It was found that it was necessary, and it was most preferable to adjust it to the range of 4.2 to 4.7. This composition is a composition in which Ni is slightly excessive with respect to the composition of Ni ₂ Si.
When [Ni] / [Si] is less than 4, the amount of solid solution Si increases, so that the conductivity is remarkably reduced, and in addition, a Si oxide film is easily formed on the material surface during heat treatment, so that the solderability and the plating property deteriorate. Cause. On the other hand, if [Ni] / [Si] exceeds 6, the desired conductivity cannot be obtained because the amount of solid solution Ni increases.
[0012]
Regarding (Equation 1) , the strength of the Cu—Ni—Si alloy is improved by precipitation of Ni ₂ Si particles. As described above, from the viewpoint of conductivity, the amount of Ni is slightly excessive with respect to the Ni ₂ Si composition. In the conventional concept, when the amount of Ni is excessive, the amount of Ni ₂ Si particles deposited is determined by the Si concentration. That is, it has been considered that in the case of a Ni excess composition, the strength after aging is determined by the Si concentration.
[0013]
The present inventors have repeated studies on the relationship between the Ni and Si concentrations and the strength based on the Ni-excess composition that provides high conductivity, and as a result, even if the [Si] / [Si] is different even at the same Si concentration, it is large. In some cases, it was found that a strength of several tens of MPa was generated, and that there was not always a correlation between the Si concentration and the strength. In other words, they found that the parameter that determines the amount of Ni2Si deposited is not the Si concentration.
Then, as a result of analyzing the experimental data based on the concept of the solubility product, the following empirical formula was obtained for the relationship between the Ni and Si concentrations and the amount of Ni ₂ Si deposited.
([Ni] -4χ) ² ([Si] -χ) = 1/8 (Equation 1)
Here, χ is a parameter indicating the amount of precipitation. More specifically, χ corresponds to the precipitated concentration, and 4 相当 corresponds to the precipitated Ni concentration. Therefore, ([Ni] -4χ) corresponds to the solid solution concentration, and ([Si] -χ) corresponds to the solid solution Si concentration.
The strength after aging shows a strong correlation with χ. That is, a desired strength can be obtained by adjusting χ to an appropriate value, and [Ni] and [Si] may be set to appropriate values using (Equation 1). As described above, a technique for controlling the strength after aging by introducing a parameter χ indicating the state of precipitation and adjusting the Ni and Si concentrations based on the relationship between the solubility products was first discovered in the present invention. It was done.
[0014]
The value of the solubility product (right side of (Equation 1)) is a function of temperature. At low temperatures, this value is small.In other words, when aging treatment is performed at low temperatures, the amount of precipitates theoretically increases, and a material with high strength and high electrical conductivity can be obtained. It is a state theory. In order to perform aging treatment of a metal material to an equilibrium state at a low temperature, an infinite aging time is required. The present inventors examined various compositions and the state of precipitation, and found that the appropriate value of the solubility product for industrial aging treatment was 1/8, and the value of Δ in this case was 0.1 to 0.45. For example, it has been clarified that a high-strength, high-conductivity material can be obtained industrially stably.
[0015]
Mg concentration Mg has the effect of significantly improving stress relaxation characteristics and the effect of improving hot workability. However, the effect cannot be obtained if the Mg content is less than 0.05%, and the castability (casting ability) exceeds 0.30%. Deterioration of skin quality), the hot workability and the heat-resistant peeling resistance of the plating are reduced, so that the Mg concentration is set to 0.05 to 0.3%.
[0016]
Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, or Be
Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag or Be have the effect of improving the strength and heat resistance of the Cu-Ni-Si alloy. Among them, Zn also has an effect of improving the heat resistance of the solder joint, and Fe has an effect of making the structure finer. Further, Ti, Zr, Al and Mn have an effect of improving hot rollability. The reason for this is that these elements have a strong affinity for sulfur and form a compound with sulfur to reduce segregation of sulfur at the ingot grain boundary which causes hot rolling cracking. If the total concentration of Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, or Be is less than 0.005%, the above effect cannot be obtained, and the total content is 2.0%. %, The conductivity is significantly reduced. Therefore, their contents are determined to be 0.005 to 2.0% in total.
[0017]
【Example】
Next, examples of the present invention will be described. Copper alloys having various component compositions shown in Table 1 were melted in an air melting furnace and cast into ingots having a thickness of 30 mm.
[0018]
[Table 1]

[0019]
Next, hot rolling was performed to a thickness of 9 mm, and a surface was removed to remove surface scale, followed by cold rolling to obtain a 1 mm thick plate. Then, after performing a solution treatment at a temperature of 750 ° C to 850 ° C, it was cold-rolled to a thickness of 0.4 mm. Then, for each alloy composition, aging treatment was performed for 3 hours at a temperature at which the tensile strength was maximized. This temperature was in the range of 400-600C. Further, a plate having a thickness of 0.25 mm was formed by cold rolling. The strength of the sample after the final heat treatment was evaluated by a tensile strength in a tensile tester. The conductivity was evaluated by conductivity (% IACS) by a four-terminal method. The values of [Ni] / [Si] and Δ were evaluated as (○) in the range of claim 1 and as (x) in the out of range. Table 1 shows the results.
[0020]
As can be seen from Table 1, Invention Example No. 1 to No. 13 is [Ni] / [Si] and all values of χ are within the scope of claim 1. Therefore, the invention example has a tensile strength of 720 MPa or more and a conductivity of 45% IACS or more, and has high strength and high conductivity.
Inventive Example No. 1 in which Mg was added to further improve the stress relaxation characteristics. In 2, 4, 6, 7, and 8, high strength and electrical conductivity were obtained as in the case where Mg was not added.
In addition, Invention Example No. 1 in which at least one of Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, and Be was added in a total amount of 0.005 to 2.0%. Inventive Examples Nos. 7 to 13 to which no additives were added. Although the conductivity is slightly inferior to those of Nos. 1 to 6, it is excellent in strength.
[0021]
On the other hand, when looking at the comparative example, In Nos. 14 and 16, since the value of Δ was higher than 0.45, the strength did not increase so much and the conductivity became low. This is because coarse Ni—Si-based particles (crystals and precipitates) that do not contribute to the strength are generated. No. No. 15 showed high conductivity, but the strength was low because the value of χ meaning the amount of precipitation was low. No. In No. 17, [Ni] / [Si] was low, Si was excessive, and the electric conductivity was low. No. Sample No. 18 had a high [Ni] / [Si], a large amount of solid solution Ni, and a low conductivity. No. In No. 19, since the value of Δ was high and [Ni] / [Si] was low, the electrical conductivity was remarkably reduced.
No. In No. 20, since the added amount of Mg was too large, workability in hot rolling was poor, cracks were generated, and the subsequent process could not be advanced.
No. In Nos. 21 to 23, the total amount when one or more elements among Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, and Be is added exceeds 2.0%. Therefore, the conductivity was extremely poor.
[0022]
【The invention's effect】
As described above, the alloy of the present invention has excellent strength and conductivity, and is suitable as a copper alloy for electronic materials such as lead frames, terminals, and connectors.

Claims (3)

In a copper-based alloy containing 1.0 to 4.5% by mass of Ni (hereinafter referred to as%) and 0.25 to 1.5% of Si, and the balance being Cu and unavoidable impurities, the mass of Ni and Si When the concentrations are [Ni] and [Si], the mass concentration ratio of Ni and Si (hereinafter referred to as [Ni] / [Si]) is 4 to 6, and χ defined by (Equation 1) is 0. A Cu—Ni—Si alloy having both high strength and high conductivity, characterized by being [Ni] and [Si] such that .1 to 0.45;
([Ni] -4χ) ² ([Si] -χ) = 1/8 (Equation 1). The Cu-Ni-Si alloy according to claim 1, containing 0.05 to 0.3% of Mg. 3. The composition according to claim 1, wherein one or more of Zn, Sn, Fe, Ti, Zr, Cr, Al, P, Mn, Ag, and Be are contained in a total amount of 0.005 to 2.0%. The Cu-Ni-Si alloy according to the above.