JPH10219374A - High strength copper alloy excellent in shearing property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copper alloy or electrical and electronic parts, excellent in shearing property as well as in characteristics of strength, electric conductivity, solderability, plating suitability, etc. SOLUTION: This copper alloy has a composition consisting of, by weight, 1.0-8.0% Ni, >0.1-2.0% Si, 0.05-5.0% Zn, <=300ppm O, and the balance essentially Cu with inevitable impurities and containing, if necessary, 0.0001-1.0%, in total, of one or >=2 elements among Mn, Mg, and Ca and also has a structure in which Ni-Si compounds are precipitated. In this case, grains of <0.03μm grain size (small grains) and grains of 0.03-100μm grain size (large grains) are present, and the ratio between the number of the small grains and that of the large grains is regulated to >=1 and also the ratio between the grain size (median) of the small grains and that of the large grains is regulated to <=0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy used for electric and electronic parts such as lead frames, terminals, connectors and springs, and more particularly to an electric and electronic part manufactured by a plurality of shearing processes including punching. Bari "
The present invention relates to a high-strength copper alloy excellent in shearing workability, such as having a small "drool" and a residual stress, and a small wear of a punching die.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned various electric and electronic parts are generally required to have characteristics such as strength, elongation, spring property, conductivity, heat resistance, Ag plating property and heat peeling resistance of solder. Therefore, for example, C64710 (Cu-3.2Ni-0.7Si-
0.3Zn) and C70250 (Cu-3.0Ni-0.
Many other copper alloys, including 65Si-0.15Mg), are used in the manufacture.

[0003]

In response to recent demands for reductions in the size, weight, and size of various electric and electronic devices and improvement in packaging density, the size of components used and the distance between leads have been accelerated. Therefore, lead frames, terminals, etc.
The requirements for dimensional accuracy have become very strict. For example, there are no "burrs" and "blunts" to prevent short circuits, and the flatness after punching is ensured to improve, for example, the accuracy of wire bonding between IC chips and lead frames. Therefore, it is desired that the residual stress after punching be small. Further, in order to improve the productivity of the punching process, it is required that the die used for the punching process has a small wear and a long mold life.

However, when various electric and electronic parts are manufactured by punching the above-mentioned conventional copper alloy, burrs and drools are large and residual stress is relatively large. It's hard to be satisfied. In addition, the die life is relatively large, and the working life is shortened.

[0005] The present invention relates to the strength required as a copper alloy for electric and electronic parts such as lead frames, terminals and connectors.
While maintaining properties such as conductivity, solderability, and plating properties more than ordinary copper alloys, it reduces burrs, drooling and residual stress generated by punching, and reduces mold wear. An object of the present invention is to improve the shearability of a copper alloy, such as extending the life.

[0006]

The high-strength copper alloy according to the present invention, which is excellent in shearability, has a Ni content of 1.0 to 8.0 wt.
%, Si: more than 0.1 to 2.0 wt%, Zn: 0.05 to
5.0 wt%, O is 300 ppm or less,
In the copper alloy in which the remainder substantially has a composition of Cu and unavoidable impurities, and in which a Ni-Si compound is precipitated,
Those having a particle size of less than 0.03 μm (small particles) and 0.
It is characterized in that particles having a size of 03 μm to 100 μm (large particles) are present, and the ratio of the number of small particles / large particles is 1 or more. In the present invention, the above-mentioned precipitation includes so-called crystallization (precipitation from molten metal). That is, in the composition of the present invention, when the content of Ni and Si is increased, Ni-
This is because the Si compound is crystallized, and in that case, both precipitated particles and crystallized particles are included. In this copper alloy, it is preferable that the ratio of the particle size of the small particles / large particles (the median value in each case) is 0.5 or less.

[0007] The above-mentioned copper alloy contains M
n, Mg, Ca group (Group A) and Fe, Zr, Ag, C
One or more kinds are selected from the group of r, Cd, Be, Sn, Ti, Co, Au, and Pt (Group B), and when they are selected from Group A, a total of 0.0001 to 1 is selected. .
0 wt%, 0.001 in total when selected from group B
When 5.0 wt% is selected from both the group A and the group B, a total of 5.0 wt% or less can be contained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the reasons for limiting the state of the components and precipitated particles (particle size of small particles and large particles, ratio of numbers, ratio of particle sizes) as described above will be described below.

[Ni amount] Ni has an effect of securing the strength and heat resistance of the alloy, and also improves the shearing workability by precipitating and crystallizing the compound in a state described later. However, if the content is less than 1.0 wt%, desired strength, heat resistance and shearability cannot be obtained, while
If Ni is contained in a proportion exceeding 8.0 wt%, the workability during hot rolling is reduced, and the bending workability and electrical conductivity of the product are significantly reduced, which is not preferable. Therefore, N
The content of i was determined to be 1.0 to 8.0 wt%. Among them, a particularly preferred range is 1.0 to 3.2 wt%.

[Amount of Si] Si improves the strength and heat resistance by precipitating a compound with Ni, and also improves the shearing workability by precipitating and crystallizing the compound in a state described later. When the content of Si is 0.1 wt% or less, precipitation and crystallization of the compound are insufficient, so that desired strength, heat resistance, and shearability cannot be obtained. on the other hand,
If the Si content exceeds 2.0% by weight, the workability during hot working is lowered and the conductivity is lowered, which is not preferable. Therefore, the content of Si is more than 0.1 to
2.0 wt% was determined. Among them, a particularly preferred range is 0.2 to 0.7 wt%.

[Zn content] Zn is a copper alloy solder and Sn
Improves heat-resistant peeling of plating. If this content is less than 0.05 wt%, the desired effect cannot be obtained.
On the other hand, if the content exceeds 5.0% by weight, the solder wettability decreases. In addition, the decrease in conductivity also becomes severe. Therefore, the content of Zn is determined to be 0.05 to 5.0 wt%.
Among them, a particularly preferable range is 0.3 to 2.0%.

[O content] O easily reacts with Si in the alloy, and if Si is captured in the alloy in an oxidized state, it inhibits the precipitation of the compound described later, and therefore the effect of improving the shearing workability is reduced. I do. In addition, the solderability, the plating property, etc., decrease. Therefore, the content of O is determined to be 300 ppm or less. Preferably, it is 100 ppm or less, more preferably 50 ppm or less.

[Small particle / large particle state] The particle size is 0.03.
Small particles of less than μm mainly improve the strength and heat resistance of the alloy but do not contribute much to the shearability. On the other hand, large particles having a particle size of 0.03 μm or more do not contribute much to the improvement of the strength and heat resistance of the alloy, but are intensively subjected to stress during shearing, become a source of microcracks, and significantly improve shearing workability. Let it. In addition, those exposed to the shear surface provide a lubricating effect between the tool and the chip, reducing the shear resistance,
In turn, it reduces mold wear. However, when the particle size is 100
The presence of particles having a size exceeding μm is not preferable because when the material is subjected to Ag plating or the like, problems such as locally increasing plating thickness (projections) occur.
The upper limit of the particles is preferably 50 μm or less, more preferably 10 μm or less. Almost all particles exceeding 5 μm are crystallized particles. When the ratio of the number of small particles / large particles is less than 1, the effect of improving strength and heat resistance is small. On the other hand, if this ratio is too large, the effect of improving the shear workability is reduced theoretically. However, under specific working heat treatment conditions (described later) for precipitating large particles, this ratio is at most about 100 to 10,000. In fact, the upper limit does not matter, since excellent shear workability is obtained even in the above ratio. Speaking by force, it can be said that there is a shearing effect of improvement if the ratio of 10 ⁸ or less. Therefore, the particle size of the precipitated particles is limited to 100 μm or less, and small particles having a particle size of less than 0.03 μm and 0.03 μm to 1 μm are included therein.
It is assumed that large particles of 00 μm exist, and small particles /
The ratio of the number of large particles was determined to be 1 or more. In addition, small particles /
When the ratio of the particle diameters of the large particles (all the median values) is larger than 0.5, the effect of improving the desired shearing workability is similarly small. Therefore, the ratio of the particle size of the small particles / large particles is set to 0.5 or less.

The method for obtaining the above-mentioned state of precipitation is, for example, as follows. 1) Ni content 4 wt%, Si content 1 wt%
Above, coarsening of the crystallized particles is particularly likely to occur. Therefore, in order to keep the size of the crystallized particles within the desired range, N
After the addition of i and Si, the molten metal is kept at a temperature of 1300 ° C. or more for 5 minutes or more, and both are completely melted, and the cooling rate in the mold from the casting temperature to the solidification temperature is 0.3 ° C./sec or more. 2) The hot-rolled material after hot rolling is rapidly cooled in water, and the cold-rolled material is heated at 500 to 700 ° C. for 1 minute to 2 hours to precipitate large particles. Thereafter, cold rolling is further added, and heating is performed at 300 to 600 ° C. for 30 minutes or more to precipitate small particles. 3) 500-500
The mixture is held at 700 ° C. for 1 minute to 2 hours to precipitate large particles, and then rapidly cooled. After further cold rolling, this time
Heating is performed at 600 ° C. for 30 minutes or more to precipitate small particles.

Further, as a method of observing the state of the above precipitation and crystallization and measuring the number and the particle size of the small particles and the large particles, for example, the following methods can be mentioned. Observation is performed in about 30 visual fields using a transmission electron microscope (TEM), a scanning electron microscope (SEM), and an optical microscope, and the distribution of the number of particles with respect to the particle size in the observation photograph is measured using an image analyzer. A transmission electron microscope is used for observing particles of less than 0.1 μm, a scanning electron microscope is used for observing particles of 0.1 to 5 μm, and an optical microscope is used for observing large particles of 5 μm or more.

"Amount of Mn, Mg, Ca" Mn, Mg, Ca
Contributes to the improvement of the hot workability of the copper alloy. But M
If the total content of one or more of n, Mg, and Ca is less than 0.0001 wt%, the desired effect cannot be obtained. On the other hand, when the content exceeds 1.0 wt% in total, the precipitation and crystallization of the above-mentioned compound are inhibited, and the improvement of the shearing property is hindered. In addition, the decrease in conductivity also becomes severe. Therefore, the content of these elements is 0.0% in total.
001 to 1.0 wt%.

[Fe, Zr, Ag, Cr, Cd, Be,
Sn, Ti, Co, Au, Pt amounts] These components have the effect of improving the strength of the copper alloy. However, the content of one or more of these components is 0.001 wt.
%, The desired effect cannot be obtained. On the other hand, when the content exceeds 5.0 wt% in total, the precipitation and crystallization of the above-mentioned compound are inhibited, and the effect of improving the shearability is hindered. Further, the electric conductivity is drastically reduced, which is not preferable. Therefore, the content of these elements is 0.00
It was determined as 1 to 5.0 wt%. When these components are contained together with the above-mentioned Mn, Mg, and Ca, the total content is 5.0 wt% or less.

[Hf, Th, Li, Na, K, Sr, P
d, W, S, P, C, Nb, Al, V, Y, Mo, P
b, In, Ga, Ge, As, Sb, Bi, Te, B,
Amount of misch metal] When the content of one or more of these components exceeds 0.1 wt% in total, precipitation of the above-mentioned compound is inhibited, and the effect of improving the shearing processability is hindered. Therefore, the content of these elements is determined to be 0.1 wt% or less in total.

[0019]

EXAMPLES Examples of the high-strength copper alloy excellent in shearing workability according to the present invention will be described together with comparative examples and conventional examples. A copper alloy having a component composition shown in Tables 1 and 2 was melted in the air under a charcoal coating in a kryptor furnace and cast into a book mold to produce an ingot of 50 mm × 80 mm × 200 mm.

[0020]

[Table 1]

[0021]

[Table 2]

The ingot was hot-rolled at about 850 ° C. and immediately quenched in water to produce a hot-rolled material having a thickness of 15 mm. In order to remove the oxide scale on the surface of the hot-rolled material, the surface was lightly cut, and then, in the examples, cold rolling-large particle precipitation treatment: 500 to 600 ° C. × 30 minutes-cold rolling-small particle precipitation treatment: 400-500 ° C. × 2-4 hours—by cold rolling,
A strip having a thickness of 0.25 mm and a width of 20 mm was prepared. Also,
By changing the conditions for the large particle precipitation treatment and the small particle precipitation treatment, the strip of the comparative example was prepared.

With respect to the obtained strip, strength, electrical conductivity, heat resistance temperature, Ag plating property, solder heat resistance peeling property, shearing property,
The state of small particles and large particles (observed with a transmission electron microscope, a scanning electron microscope and an optical microscope) was measured. The results are as shown in Tables 3 and 4.

[0024]

[Table 3]

[0025]

[Table 4]

The Ag plating property was evaluated by observing the presence or absence of a phenomenon (projection) of locally increasing the thickness when cyan-based Ag plating was performed at a thickness of 1 μm. Solder heat-peelability is as follows: 6Sn / 4Pb solder was soldered at 245 ± 5 ° C. × 5 seconds, and then 1000 ° C. in a 150 ° C. oven.
Heated to Hr. This test piece was processed by bending it back by 180 °, and it was observed whether the solder in the processed portion was peeled off. The heat-resistant temperature is a temperature at which the amount of decrease in Hv after heating for 5 minutes becomes 10% of Hv before heating. The shearing workability was expressed by punching a lead having a length of 30 mm and a width of 0.5 mm with a press, and measuring the lead width, the amount of “burr” and the amount of “sag”.

The precipitated and crystallized particles are obtained by a transmission electron microscope,
Observation was performed in 30 fields of view with a scanning electron microscope and an optical microscope, respectively, and the distribution of the number of particles with respect to the particle size (particle diameter) in the observation photograph was measured using an image analyzer (manufactured by Nireco Corporation, trade name: Luzex). . In particular,
The transmission electron microscope determines the particle size and the number of particles larger than 0.03 μm at an observation magnification of 60,000 times (observation area: 2 μm 2). 0.003μm diameter
Up to the particles were measured. The scanning electron microscope observed particles of 0.1 to 5 μm at 5000 times, and the optical microscope observed particles of 5 μm or more at 400 times. In addition, the value of the largest number of particles (median value) was used for the sizes of the small particles and the large particles. The ratio between the size of the small particles and the size of the large particles was the ratio of the median.

From Tables 3 and 4, it can be seen that the alloy No. 1-12
Has excellent properties such as strength, electrical conductivity, heat resistance temperature, and Ag plating properties required for electric and electronic parts, and also has excellent shearing workability. In addition, the improvement of the shearing processability is manifested as an effect of small burrs and "sags" and a high precision of lead width dimensions.Moreover, since "burrs" and "sags" are small, It can be presumed that the residual stress is small. On the other hand, in Comparative Example No. 13 to 23 show that any of the performances is low.

[0029]

The copper alloy of the present invention has the characteristics required as a copper alloy for electric and electronic parts, and further, for example, shears various electric and electronic parts such as lead materials of semiconductor devices and terminals and connectors. When manufactured by stamping or the like, "burrs", "blunts" and residual stress are small, and the dimensional accuracy is good. Further, since the shearing workability is excellent, the wear of the punching die is suppressed, and the service life of the punching die is prolonged. Therefore, it is possible to meet strict requirements for dimensional accuracy due to miniaturization of various electric and electronic devices. Also,
Since the service life of the punching mold is extended, the productivity of stamping is also improved.

Claims (6)

[Claims] 1. Ni: 1.0 to 8.0 wt%, Si:
More than 0.1-2.0 wt%, Zn: 0.05-5.0 wt%
%, O is 300 ppm or less, the balance is substantially composed of Cu and unavoidable impurities, and Ni-S
Among copper alloys in which i-compounds are precipitated, there are those having a particle size of less than 0.03 μm (hereinafter, referred to as small particles) and those having a particle size of 0.03 μm to 100 μm (hereinafter, referred to as large particles), and small particles. / A high-strength copper alloy excellent in shearability, characterized in that the ratio of the number of large particles is 1 or more. 2. The high-strength copper alloy according to claim 1, wherein the ratio of the particle size of the small particles / large particles (the median value thereof) is 0.5 or less. 3. The shearing processability according to claim 1, further comprising one or more of Mn, Mg, and Ca in a total amount of 0.0001 to 1.0 wt%. Excellent high strength copper alloy. 4. Further, Fe, Zr, Ag, Cr, C
The shearing process according to claim 1, wherein one or more of d, Be, Sn, Ti, Co, Au, and Pt are contained in a total of 0.001 to 5.0 wt%. High-strength copper alloy with excellent properties. 5. The method according to claim 1, wherein one or more of Mn, Mg and Ca is 0.0001 to 1.0 wt% in total, and
e, Zr, Ag, Cr, Cd, Be, Sn, Ti, C
One, two or more of o, Au, and Pt are used in a total of 0.0
3. The high-strength copper alloy according to claim 1, wherein the high-strength copper alloy has an amount of from 0.01 to 5.0% by weight in a total amount of 5.0% by weight or less. 6. Hf, Th, Li, Na, K, Sr, P
d, W, S, P, C, Nb, Al, V, Y, Mo, P
b, In, Ga, Ge, As, Sb, Bi, Te, B,
One or more of the misch metals total 0.1
The high-strength copper alloy according to any one of claims 1 to 5, which is not more than wt%.