JP2001207229A - Copper alloy for electronic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy having good bendability as well as high strength and electric conductivity. SOLUTION: This alloy has a composition containing, by mass, 1.5 to 3.5% Ni and 0.35 to 1.0% Si, furthermore containing 0.005 to 0.1% Fe and/or one or more kinds of Zr, Cr, Ti and Mo of 0.005 to 0.2% in total, in which, by a weight ratio, Ni/Si is also controlled to 3 to 7, and the balance Cu with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy for electronic materials having strength, conductivity, and good bendability and punchability.

[0002]

2. Description of the Related Art Copper alloys for electronic materials used in lead frames, terminals, connectors and the like are required to have both high strength and high electrical or thermal conductivity as basic characteristics of products. In addition, recent miniaturization of electronic components,
As higher integration is required, the thickness of the material is required to be reduced, and lead frames, terminals, and connectors are increasing in the number of leads and the pitch is becoming narrower. In addition, due to the complexity of component shapes and the demand for improved reliability in assembly and mounting, the materials used are required to have excellent mechanical strength and electrical conductivity, as well as good bending workability.

In recent years, copper alloys for electronic materials have been replaced by solid solution strengthened copper alloys represented by conventional phosphor bronze and brass.
From the viewpoint of high strength and high conductivity, the amount of age hardening type copper alloy is increasing. Age-hardened copper alloys are subjected to aging of a solution-treated supersaturated solid solution, whereby fine precipitates are uniformly dispersed and the strength of the alloy is increased. Conductivity is improved.
Therefore, it is used as a material having excellent mechanical properties such as strength and spring property, as well as good electrical and thermal conductivity. Among the age hardening type copper alloys, Cu-Ni-Si based copper alloy is a typical copper alloy having both high strength and high electrical conductivity, and has been put to practical use as a material for electronic devices.

[0004]

SUMMARY OF THE INVENTION Cu-Ni-Si alloys are:
Precipitation of fine Ni-Si intermetallic compound particles in the copper matrix increases strength and electrical conductivity. However, a composition with a low concentration of Ni and Si added provides sufficient electrical conductivity but lacks strength, while a composition with a high concentration provides sufficient strength, but has a reduced conductivity and further bending. However, there was a problem that the moldability was easily lowered. To ensure strength and workability,
Although other elements such as Sn may be added, the conductivity is greatly reduced.

It is generally said that the bendability of an alloy is related to the grain size, and it is said that the smaller the grain size, the better the bendability. However, when the crystal grain size is adjusted to be small, a mixed grain structure in which unrecrystallized portions are mixed easily even when manufacturing conditions are controlled, resulting in a problem that bendability is reduced. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been developed in order to solve the above problems.
An object of the present invention is to provide a copper alloy for electronic materials that is excellent in bending workability in Ni-Si alloys.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventor repeatedly conducted research on Cu-Ni-Si based alloys, and found that Cu-Ni-Si based alloys contained Fe and / or Zr, C
After adjusting the composition by adding at least one of r, Ti, and Mo, Mg, Zn, Sn, Al, P, Mn, Ag or B
It has been found that a material suitable as a copper alloy for electronic materials can be provided by including e.

That is, the present invention has been completed on the basis of the above findings. (1) 1.5-3.5% Ni, 0.35-1.0% Si,
Contains 0.005-0.1% Fe, and Ni / Si = 3-7 by weight
A copper alloy for electronic materials with excellent strength, conductivity and bendability, with the balance being adjusted to become Cu and inevitable impurities. (2) 1.5-3.5% Ni, 0.35-1.0% Si, Zr, C
Adjust so that the total content of at least one of r, Ti, and Mo is 0.005 to 0.2%, and the weight ratio is Ni / Si = 3 to 7, and the balance consists of Cu and unavoidable impurities. A copper alloy for electronic materials with excellent strength, conductivity and bending properties.

(3) 1.5-3.5% Ni, 0.35-1.0% Si,
0.005 to 0.1% Fe and at least one of Zr, Cr, Ti and Mo in a total amount of 0.005 to 0.2%, and N in weight ratio
A copper alloy for electronic materials with excellent strength, conductivity and bendability, characterized in that i / Si is adjusted to 3 to 7 and the balance consists of Cu and unavoidable impurities. (4) 1.5-3.5% Ni, 0.35-1.0% Si, 0.005-0.1%
Fe, Mg, Zn, Sn, Al, P, Mn, A
containing at least one of g or Be in a total amount of 0.005 to 2.0%,
And adjust so that Ni / Si = 3 ~ 7 by weight ratio, and the rest is
Strength consisting of Cu and unavoidable impurities,
Copper alloy for electronic materials with excellent conductivity and bending workability.

(5) 1.5 to 3.5% Ni, 0.35 to 1.0% Si, and at least one of Zr, Cr, Ti and Mo in total
0.005 to 0.2%, and Mg, Zn, Sn, Al,
0.005 to 2.0% in total of at least one of P, Mn, Ag or Be
Copper for electronic materials with excellent strength, conductivity and bendability characterized by containing and adjusting the weight ratio of Ni / Si to 3-7, with the balance being Cu and unavoidable impurities alloy. (6) 1.5-3.5% Ni, 0.35-1.0% Si, 0.005-0.1%
Fe is contained, and at least one of Zr, Cr, Ti, and Mo is contained in a total amount of 0.005 to 0.2%, and Mg, Zn, Sn, A
at least one of l, P, Mn, Ag or Be in a total amount of 0.005 to
Electronic material with excellent strength, conductivity and bendability, characterized by containing 2.0% and adjusting the weight ratio of Ni / Si to 3-7, with the balance being Cu and unavoidable impurities The present invention provides a copper alloy for use.

[0010]

Next, the reason why the composition range of the copper alloy in the present invention is limited as described above will be described together with its operation. (1) Ni and Si Ni and Si are subjected to aging treatment to form fine particles of intermetallic compounds, mainly Ni ₂ Si, mutually finely, thereby significantly increasing the strength of the alloy. , Maintain high electrical conductivity. However, if the Ni content is less than 1.5% or the Si content is less than 0.35%, the desired strength cannot be obtained even if the other component is added.
If the content exceeds 1.0%, sufficient strength is obtained, but the desired electrical conductivity is reduced, and coarse Ni-Si-based particles (crystallized material) that do not contribute to the improvement of the strength are obtained. And precipitates) are formed in the matrix, which causes deterioration in bending workability, etching property and plating property. Therefore, the content of Ni is set to 1.5 to 3.5%, and the content of Si is set to 0.35 to 1.0%.

The weight ratio of the amount of Si to the amount of Ni (referred to as Ni / Si) is 3
The reason for defining as ~ 7 is that by increasing the weight ratio of Ni and Si in the alloy to the concentration ratio of Ni and Si in the intermetallic compound Ni ₂ Si, the electrical conductivity after aging treatment can be further increased. This is because it can be done. If Ni / Si is less than 3, the ratio of Si to Ni ₂ Si
In addition to the decrease in electrical conductivity due to excessive concentration,
When the amount of solid solution Si in the matrix increases, an Si oxide film easily forms on the surface of the material during heat treatment, which causes deterioration in solderability and plating property.

Although the weight ratio to the Ni ₂ Si composition is Ni / Si = 4, the Ni content should be slightly excessive with respect to the Ni ₂ Si composition in order to reduce the amount of solid solution Si as much as possible. But Ni / Si is more than 7 when the Ni ₂ Si excess relative composition Ni
The desired amount of electrical conductivity cannot be obtained due to the large amount.
Therefore, the weight ratio of Si and Ni for obtaining good electrical conductivity is
Ni / Si = 3-7, with 4.5 being most preferred.

(2) Fe Since Fe has a high melting point, it is finely crystallized and precipitated in the solidification during casting and in the cooling stage after solidification, and is a main component of the alloy of the present invention.
When Fe and Ni compounds are crystallized and precipitated, fine Fe particles serve as nuclei, and have the effect of suppressing the coarsening of Ni-Si particles. In addition, in the annealing process with recrystallization after cold rolling, Fe particles distributed in the matrix have the effect of preventing grain boundary movement by the pinning effect and suppressing the coarsening of recrystallized grains. A fine and uniform recrystallized structure can be obtained.

Therefore, the bendability of the alloy can be improved by reducing the crystal grain size. Further, Fe has the effect of improving the strength and heat resistance of the alloy. However, if the Fe content is less than 0.005%, none of the effects can be obtained, and if it exceeds 0.1%, the conductivity is reduced, the Fe particles in the matrix are coarsened, and the bendability and the plating property are reduced. Was determined to be 0.005 to 0.1%.

(3) Zr, Cr, Ti, Mo Since Zr, Cr, Ti, and Mo are all high-melting elements, they have the same effect as Fe in suppressing the coarsening of Ni-Si particles and in annealing involving recrystallization. Since a fine crystal structure is obtained, there is an effect of improving bendability. Zr, Cr, Ti, and Mo can be added in combination. However, if the total content is less than 0.005%, the desired effect cannot be obtained. If it exceeds 0.2%, workability is reduced. The conductivity decreases. Therefore, Zr, Cr, T
The total amount of i and Mo added was determined to be 0.005 to 0.2%.

(4) Mg, Zn, Sn, Al, P, Mn, Ag or B
e Cu-Ni-Si is used for Mg, Zn, Sn, Al, P, Mn, Ag or Be.
It has the effect of improving the strength and heat resistance of the system copper alloy. Of these, Zn has the effect of improving the heat resistance of the solder joint, and Mg, Al and Mn also have the effect of improving the hot rolling property. The reason for this is that these elements have a strong affinity for sulfur and form a compound with sulfur, thereby reducing the segregation of sulfur at the ingot grain boundary, which causes hot rolling cracking.

If the total content of Mg, Zn, Sn, Al, P, Mn, Ag or Be is less than 0.005%, the above effects cannot be obtained. On the other hand, if the total content exceeds 2.0%, the electric conductivity will not increase. Properties are significantly reduced. Therefore, their content is 0.005 to 2.0 in total.
%. As described above, the copper alloy according to the present invention exhibits excellent strength and electrical characteristics and also has excellent bending workability.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Copper alloys having various component compositions shown in Table 1 were melted in a high-frequency melting furnace and cast into ingots having a thickness of 20 mm.

[0019]

[Table 1]

Next, the ingot was hot-rolled to a thickness of 8 mm, surface-polished to remove surface scale, and then cold-rolled into a 1 mm-thick plate. After that, 750 ~
After solution treatment at a temperature of 850 ° C, it was cold-rolled to 0.4 mm. Then, in the range of 400 to 600 ° C, perform aging treatment for 5 hours each at the temperature at which the maximum strength is obtained for each composition.
Then, cold-rolled thickness to obtain higher strength
The plate was made 0.25 mm and finally heat-treated at a temperature of 400 to 500 ° C for 30 seconds to 1 hour.

Various properties were evaluated for each of the alloys thus obtained. Regarding the strength, the tensile strength was measured by a tensile tester. Electrical conductivity is conductivity (% IAC
S) was evaluated. The grain size of the material after the final heat treatment was measured by a cutting method according to JISH0501 along an axis perpendicular to the plate surface. The bending property was measured by a W bending test using a 10 mm wide strip specimen with a bending radius of the same thickness as the plate thickness and a load of 5 tons, and a bending test in the direction parallel to the rolling direction (the bending axis was perpendicular to the rolling direction). The surface of the bent part after the test was observed with an optical microscope (magnification of 50 times or more) and SEM. Are shown in Table 1 as x.

As can be seen from Table 1, the alloys of the present invention have excellent strength and conductivity, and all have a fine grain size and good bendability. On the other hand, the comparative alloy has a partly different composition from the alloy of the present invention. N
In the case of o.2, the conductivity is inferior because of high Ni. No. 3 is inferior in conductivity and bending workability due to high Si. In Nos. 4 and 6, Fe and Mo were low, respectively, so that the crystal structure was a mixed grain structure in which unrecrystallized grains and recrystallized grains were mixed, and coarse Ni-Si particles were formed, and the bendability was reduced. In Nos. 5 and 7, since Fe and Cr were high, coarse Fe or Cr particles were formed in the matrix, and the bendability was lowered. In No. 8, the total of Zr and Ti exceeded the range of the present invention, and the bendability was reduced due to the generation of Zr and Ti particles. No. 9 is inferior in conductivity because it contains subcomponents beyond the range. Nos. 10 and 11 have the same composition as the alloy of the present invention, but differ in the Ni / Si ratio.
Since the ratio is low, the conductivity is poor. No. 11 is inferior in conductivity because of a large Ni / Si ratio.

[0023]

As described above, the alloy of the present invention has excellent strength and electric conductivity, and also has good bendability, and is suitable as a copper alloy for electronic materials such as lead frames, terminals and connectors. is there.

Claims (6)

[Claims] (1) 1.5-3.5 mass% (hereinafter referred to as%) of N
i, contains 0.35 to 1.0% Si, 0.005 to 0.1% Fe, and is adjusted to have a weight ratio of Ni / Si = 3 to 7, with the balance being Cu and unavoidable impurities. Copper alloy for electronic materials with excellent strength, conductivity and bendability. 2. The composition contains 1.5 to 3.5% of Ni and 0.35 to 1.0% of Si, and further contains at least one of Zr, Cr, Ti and Mo in a total amount of 0.005 to 0.005%.
An electronic material with excellent strength, conductivity and bendability characterized by containing 0.2% and adjusting the weight ratio of Ni / Si to 3-7, with the balance being Cu and unavoidable impurities For copper alloy. (3) 1.5 to 3.5% Ni, 0.35 to 1.0% Si, 0.005 to
It contains 0.1% Fe, and further contains at least one of Zr, Cr, Ti, and Mo in a total amount of 0.005 to 0.2%.
A copper alloy for electronic materials with excellent strength, conductivity and bendability, adjusted to 3 to 7, with the balance being Cu and unavoidable impurities. (4) 1.5-3.5% Ni, 0.35-1.0% Si, 0.005-
Contains 0.1% Fe and, if necessary, Mg, Zn, Sn, Al,
0.005 to 2.0% in total of at least one of P, Mn, Ag or Be
Copper for electronic materials with excellent strength, conductivity and bendability characterized by containing and adjusting the weight ratio of Ni / Si to 3-7, with the balance being Cu and unavoidable impurities alloy. 5. A composition containing 1.5 to 3.5% of Ni and 0.35 to 1.0% of Si and further containing at least one of Zr, Cr, Ti and Mo in a total amount of 0.005 to 0.5%.
2%, Mg, Zn, Sn, Al, P, Mn, Ag
Or containing at least one of Be in a content of 0.005 to 2.0%,
And adjust so that Ni / Si = 3 ~ 7 by weight ratio, and the rest is
Strength consisting of Cu and unavoidable impurities,
Copper alloy for electronic materials with excellent conductivity and bending workability. (6) 1.5-3.5% Ni, 0.35-1.0% Si, 0.005-
It contains 0.1% Fe and contains at least one of Zr, Cr, Ti and Mo in a total amount of 0.005 to 0.2%.
at least one of n, Sn, Al, P, Mn, Ag or Be in total
Excellent in strength, conductivity and bending workability characterized by containing 0.005 to 2.0% and adjusting the weight ratio of Ni / Si to 3 to 7 with the balance being Cu and unavoidable impurities Copper alloy for electronic materials.