JP3383615B2 - Copper alloy for electronic materials and manufacturing method thereof - Google Patents

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, which has excellent strength and conductivity, and further has good bending workability, etching property and plating property, and a method for producing the same.

[0002]

2. Description of the Related Art Copper alloys for electronic materials used for lead frames, terminals, connectors, etc. are required to have both high strength and high electrical or thermal conductivity as basic characteristics of products. Furthermore, miniaturization of electronic parts in recent years,
Since higher integration is further required, lead frames, terminals, and connectors are correspondingly increasing in the number of leads and narrowing the pitch. Furthermore, due to the complexity of parts shape and the demand for improved reliability in assembly and mounting, the materials used are not only excellent in mechanical strength and electrical conductivity, but also resistant to bending and repeated bending, and have good etching properties. And good plating property is required.

From the viewpoint of high strength and high conductivity, in recent years, as the copper alloy for electronic materials, the amount of age hardening type copper alloy used in place of the solid solution strengthening type copper alloy represented by the conventional phosphor bronze, brass and the like. Is increasing. Age-hardening type copper alloy is a solution-treated supersaturated solid solution, and by aging treatment, fine precipitates are dispersed uniformly and the strength of the alloy is increased. The conductivity is improved.
Therefore, it is used as a material which is excellent in mechanical properties such as strength and spring property, and is also excellent in electrical conductivity and thermal conductivity. Here, there are many active elements as precipitation elements. Further, an active metal may be further added for the purpose of improving the properties of the alloy.

Among age hardening type copper alloys, Cu-Ni-S
The i-based copper alloy is a typical copper alloy having both high strength and high conductivity, and has been put to practical use as a material for electronic devices.
This copper alloy has increased strength and conductivity due to the deposition of fine Ni-Si-based intermetallic compound particles in the copper matrix.

[0005]

The Cu-Ni-Si alloy has a high strength and a high electric conductivity due to the precipitation of fine Ni-Si intermetallic compound particles in the copper matrix, but the strength is improved. Coarse crystallized substances that do not contribute to the oxidization are likely to remain in the matrix, and since Si is active and oxides are easily generated, relatively large particles such as these crystallized substances and oxides are present in the matrix. It is easy to become an organization. The presence of these coarse particles increases the amount of smut generated during etching. Then, when the lead is left as a protrusion on the end surface of the lead after etching, when the lead has a narrow pitch,
Abnormal electrodeposition may occur on the protrusions during plating, resulting in electrical failure such as a short circuit. Further, there is a possibility that problems such as peeling of the plating, swelling of the plating, stains, and generation of protrusions (squash) may occur during plating. Furthermore, when bending is performed, it becomes a starting point of crack generation, which becomes a factor of reducing the workability of the product.

The present invention has been made to solve the above-mentioned problems, and provides a copper alloy for electronic materials which has sufficient strength and electric conductivity, and is further excellent in bending workability, etching property and plating property. The purpose is to do.

[0007]

In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive research on precipitation-type copper alloys and found that they are necessary after adjusting the composition of Cu-Ni-Si alloys. Depending on Mg, Zn, Sn, Fe, Ti, Zr,
By containing Cr, Al, P, Mn, Ag, and Be and controlling / selecting the manufacturing conditions to control the distribution of precipitates, crystallized substances, inclusions such as oxides in the matrix, It has been found that a material suitable as a copper alloy for materials can be provided.

The present invention has been completed based on the above findings, and (1) contains 1.0 to 4.8 mass% Ni and 0.2 to 1.4 mass% Si, and the balance Cu.
And inevitable impurities, the size of inclusions is 10 μm or less, and the number of inclusions having a size of 5 to 10 μm is less than 50 / mm ^{2 in} a cross section parallel to the rolling direction. A copper alloy for electronic materials with excellent strength and conductivity. And (2) 1.0 to 4.8 mass% Ni
And 0.2 to 1.4 mass% of Si, and S
The content (mass%) of Ni with respect to i is adjusted to be 2 to 8, the balance is Cu and inevitable impurities, and the size of inclusions is 10 μm or less and the size is 5 to 10 μm. A copper alloy for electronic materials having excellent strength and conductivity, wherein the number of inclusions is less than 50 / mm ^{2 in} a cross section parallel to the rolling direction. And (3) 1.
0-4.8 mass% Ni and 0.2-1.4mass
containing s% Si, and further containing Mg, Zn, Sn, Fe,
The total content of one or more of Ti, Zr, Cr, Al, P, Mn, Ag or Be is 0.005 to 2.0 mass%, the balance is Cu and inevitable impurities, and the size of inclusions. Is 10 μm or less, and 5 to 10 μm
The number of inclusions having a size of less than 50 / mm ^{2 in} a cross section parallel to the rolling direction is a copper alloy for electronic materials having excellent strength and conductivity. And (4) 1.0 to 4.8 m
ass% Ni and 0.2-1.4 mass% Si,
Furthermore, Mg, Zn, Sn, Fe, Ti, Zr, Cr, A
1 or more of 1, P, Mn, Ag or Be is contained in a total amount of 0.005 to 2.0 mass% and adjusted so that the content ratio of Ni to Si (mass%) is 2 to 8. The balance consists of Cu and unavoidable impurities, and the size of inclusions is 10 μm or less, and 5 to 10
The number of inclusions with a size of μm is 5 in the cross section parallel to the rolling direction.
A copper alloy for electronic materials excellent in strength and conductivity, characterized in that it is less than 0 pieces / mm ² . And (5) 800 ingots
After heating for 1 hour or more at a temperature of ℃ or more and less than 900 ° C, hot rolling is performed at a hot rolling end temperature of 650 ° C or more, and then the heat treatment and rolling are performed.
The method for producing a copper alloy for electronic materials according to any one of (1) to (4) , characterized in that the aging treatment is performed at a temperature of ˜650 ° C. for 1 to 10 hours. The present invention relates to a copper alloy having sufficient strength and electrical conductivity for a lead frame, a terminal and a connector, as well as good bending workability, etching property and plating property, and a manufacturing method thereof.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, "inclusion" means
Crystallized substances that are generally coarse during the solidification process during casting and oxides, sulfides, etc. generated by the reaction in the molten metal during melting, as well as after the solidification process during casting, that is, the cooling process after solidification, heat Precipitates generated by precipitation reaction in the solid phase matrix during the cooling process after solution rolling and after solution heat treatment and during aging treatment, and include coarse particles observed in the matrix by SEM observation of the present copper alloy Is. "Size of inclusion" means the diameter of the smallest circle including the inclusion under SEM observation of the inclusion. “Number of inclusions” means SEM after etching in a cross section parallel to the rolling direction of the material.
It is the number of inclusions per unit square mm actually counted at many points by observation.

[0010] Then why the composition range and inclusion size of Oite copper alloy in the present invention is limited to as of the will be described together with its operation. (1) Ni and Si Ni and Si are Ni and Si by aging treatment.
Form fine particles of intermetallic compounds mainly composed of Ni ₂ Si and minutely increase the strength of the alloy.
Maintain high electrical conductivity. However, the Ni content is 1 ma
When the content is less than ss% or the Si content is less than 0.2 mass%, the desired strength cannot be obtained even when the other component is added, and the Ni content exceeds 4.8 mass% or Si.
If the content exceeds 1.4 mass% , a sufficient strength is obtained, but the desired electrical conductivity is lowered, and further, a coarse Ni—S that does not contribute to the improvement of strength is obtained.
i-type particles (crystallized substances and precipitates) are generated in the mother phase, which causes deterioration of bending workability, etching property and plating property. Thus, defining the content of Ni from 1.0 to 4.8 mass%, the content of Si and 0.2 to 1.4 mass%. Further, in order to further increase the electrical conductivity after the aging treatment, the content ratio of Ni and Si in the alloy is set to Ni ₂ S which is an intermetallic compound.
It is desirable to approach the content ratio of Ni and Si of i.
The content ratio of Ni to Si ( mass% ) (Ni content / Si content) for obtaining good electric conductivity is 2 to
8, with 4 being most preferred.

(2) Mg, Zn, Sn, Fe, Ti, Zr, Cr, A
1, P, Mn, Ag or Be Mg, Zn, Sn, Fe, Ti, Zr, Cr, Al,
P, Mn, Ag or Be has an effect of improving the strength and heat resistance of the Cu-Ni-Si based copper alloy. Further, among these, Zn also has an effect of improving heat resistance of the solder joint portion, and Fe also has an effect of refining the structure. Further, Mg, Ti, Zr, Al and Mn also have an effect of improving 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 boundaries, which causes hot rolling cracks. Mg, Zn, Sn, Fe, Ti, Z
If the total content of r, Cr, Al, P, Mn, Ag, or Be is less than 0.005 mass% , the above effect is not obtained, while if the total content exceeds 2.0 mass% , electricity is not generated. The conductivity is significantly reduced. Therefore, the total content of these is set to 0.005 to 2.0 mass% .

(3) Inclusions In this alloy system, particles of inclusions may be present in the matrix. Precipitates for obtaining the strength required for this alloy are fine, and coarse precipitates exceeding 0.5 μm and inclusions such as crystallized substances do not contribute to the strength, and especially the size exceeds 10 μm. Such a material remarkably deteriorates bending workability, etching property and plating property. In order to prevent such a problem, it is necessary to set the upper limit of the size of the coarse inclusions to 10 μm. Further, the present inventor investigated the correlation between the distribution of inclusions and bending workability, etching property, and plating property, and even with coarse inclusions of 5 to 10 μm, 50 / It has been found that if it is less than mm ² , these characteristics are not impaired.

Next, a manufacturing method for obtaining this alloy will be described. Usually, the ingot is manufactured by a semi-continuous casting method. In the solidification process during casting in semi-continuous casting, coarse Ni—Si-based crystallized substances and precipitates may be formed. These coarse inclusions are heated at a temperature of 800 ° C. or higher for 1 hour or more and then hot-rolled to a finish temperature of 65 ° C.
By setting the temperature to 0 ° C. or higher, solid solution occurs in the matrix. However, when the heating temperature is 900 ° C. or higher, a large amount of scale is generated and cracks are generated during hot rolling. Therefore, the heating temperature is preferably 800 ° C. or higher and lower than 900 ° C.

In order to obtain a high-strength material by the aging treatment, it is possible to perform the solution treatment before the aging treatment, and the higher the solution treatment temperature is, the more solid solution amount of Ni and Si is in the matrix. Ni-from the matrix during aging treatment
Si-based intermetallic compounds are finely precipitated to further improve the strength. In order to obtain this effect, the solution treatment temperature is 75
It is desirable that the temperature is 0 ° C. or higher, preferably 800 ° C. or higher and lower than 900 ° C. In the copper alloy of the present invention, at 900 ° C., Ni and Si are sufficiently dissolved in the matrix,
At a temperature of 900 ° C. or higher, the surface of the material is heavily oxidized during the solution treatment, and the load of the pickling step for removing the oxide layer increases, so a treatment temperature of less than 900 ° C. is recommended.

Further, in order to improve the strength after the aging treatment, cold rolling is performed before the aging treatment, and the higher the workability, the higher the strength obtained. The workability is appropriately selected according to the strength and workability required for the copper alloy of the present invention.

The aging treatment is carried out in order to obtain the desired strength and electrical conductivity, but the aging treatment temperature must be 300 to 650 ° C. If the temperature is lower than 300 ° C, the aging treatment takes time, which is not economical. If the temperature exceeds 650 ° C, the Ni-Si particles are coarsened. This is because it does not improve. When performing the aging treatment in the range of 300 to 650 ° C., sufficient strength and electrical conductivity can be obtained if the aging treatment time is 1 to 10 hours. In order to further improve the strength of the copper alloy of the present invention, it is possible to perform cold rolling after the aging treatment and then perform heat treatment (strain relief annealing).

[0017]

Example Copper alloys having various composition shown in Table 1 were melted in a high frequency melting furnace and cast into an ingot having a thickness of 20 mm. Next, this ingot was hot-rolled at a temperature shown in Table 1 up to a thickness of 8 mm under each temperature condition, chamfered to remove surface scale, and then cold-rolled to a thickness of 2 m.
m plate. After that, solution treatment was performed at a temperature of 750 ° C. or higher and lower than 900 ° C. for 10 minutes, and then cold rolling was performed to 0.5 mm. Then, aging treatment is performed for 5 hours at a temperature at which the highest temperature is obtained in each composition of 400 to 600 ° C., and thereafter, a plate having a thickness of 0.15 mm is cold-rolled so that higher strength can be obtained. At 500-550 ° C for 30
Strain relief annealing was appropriately performed for 10 seconds.

[0018]

[Table 1]

Various properties of the alloys thus obtained were evaluated. Regarding the strength, the tensile strength was measured with a tensile tester. Electrical conductivity is conductivity (% IAC
It was evaluated by S). Repeatable bendability is "bend radius /
With a plate thickness of 1 ", the bending axis was repeatedly bent 90 degrees on one side in a direction parallel to the rolling direction, and the number of times until break was counted was evaluated by the method of counting the number of reciprocations as one. In addition, the evaluation criteria of the repetitive bendability were evaluated as ◯ when the number of bending was 3 or more, and as × when less than 3 times. The etching property is that the cross section perpendicular to the rolling direction of the sample is etched by 10 μm with an aqueous ferric chloride solution,
When the etching surface is observed with a three-dimensional coordinate measuring device and protrusions of inclusions of 5 μm or more are observed with respect to the substrate, x
And the case where it was not observed was marked with ◯. Platability is
After silver plating having a thickness of 5 μm was applied to the surface of the sample, the surface of the silver plating was observed and the case where a crush of silver having a size of 10 μm or more was observed was marked with x, and the case where it was not observed was marked with ◯. The number of inclusions is the number of inclusions having a size of 5 to 10 μm per unit square mm, which was actually counted at a large number of locations by observing a cross section parallel to the rolling direction of the material with an SEM after etching.

As can be seen from Table 1, the present invention is excellent,
It has strength, conductivity, repetitive bendability, etching property, and silver plating property. On the other hand, the comparative alloy No. 1 to N
o. No. 5 is different from the present invention in a part of the composition, the heating temperature before hot rolling is less than 800 ° C., and the hot rolling end temperature is less than 650 ° C. However, when compared with the alloy of the present invention, Comparative alloy No. No. 1 is low in Ni and therefore inferior in strength and conductivity. Comparative alloy No. No. 2 is inferior in strength because both Ni and Si are low. Comparative alloy No. Since 3 and 4 have a high Si content, the conductivity is poor. Comparative alloy No. Sample No. 5 contains subcomponents exceeding the allowable range of the present invention, and thus has poor electrical conductivity.

Further, in Comparative Example No. 1, 3, 4, 6, 7,
Since No. 8 has a large number of inclusions, it is inferior in repeated bending property, etching property and silver plating property. Especially in Comparative Example No. 6, 7,
No. 8 is the example No. Although the composition is the same as that of Nos. 1 and 9, since the heating temperature before hot rolling and the end temperature of hot rolling are low, coarse crystallized substances and precipitates generated during casting are heated before hot rolling, hot rolling. This is an example in which the number of inclusions increased as a result of not forming a solid solution. In order to investigate the cause of generation of silver lumps generated by silver plating, the surface immediately below the silver lumps was observed after the silver plating was peeled off, and as a result, coarse Ni—Si-based inclusions were confirmed.

[0022]

As described above, according to the present invention, it is possible to obtain a copper alloy having excellent strength and electrical conductivity, as well as excellent repetitive bendability, etching property and plating property. Suitable as a copper alloy for electronic materials such as terminals, connectors.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI C22F 1/00 691 C22F 1/00 691B 691C

Claims (5)

(57) [Claims] 1. Ni to 1.0 to 4.8 mass% and 0.
2 to 1.4 mass% of Si, the balance of Cu and inevitable impurities, and the size of inclusions is 10
A copper alloy for electronic materials excellent in strength and conductivity, characterized in that the number of inclusions having a size of 5 μm or less and having a size of 5 to 10 μm is less than 50 / mm ^{2 in} a cross section parallel to the rolling direction. 2. Ni to 1.0 to 4.8 mass% and 0.
The content of Si is 2 to 1.4 mass%, and the content ratio of Ni to Si (mass%) is adjusted to 2 to 8 with the balance being Cu and inevitable impurities, and the size of inclusions. Is 10 μm or less, and 5 to 10
The number of inclusions with a size of μm is 5 in the cross section parallel to the rolling direction.
A copper alloy for electronic materials, which is excellent in strength and conductivity, characterized in that it is less than 0 pieces / mm ² . 3. Ni of 1.0 to 4.8 mass% and 0.
2 to 1.4 mass% of Si is contained, and further Mg, Z
n, Sn, Fe, Ti, Zr, Cr, Al, P, Mn,
The total amount of one or more of Ag and Be is 0.005-2.
0 mass%, the balance is Cu and inevitable impurities, and the size of inclusions is 10 μm or less,
Further, the number of inclusions having a size of 5 to 10 μm is less than 50 / mm ^{2 in} a cross section parallel to the rolling direction, and a copper alloy for electronic materials having excellent strength and conductivity. 4. Ni- of 1.0 to 4.8 mass% and 0.
2 to 1.4 mass% of Si, and further Mg, Zn, S
0.005 to 2.0 ma in total of one or more of n, Fe, Ti, Zr, Cr, Al, P, Mn, Ag or Be.
ss% content and Ni content relative to Si (mas
s%) is adjusted to be 2 to 8, the balance is Cu and inevitable impurities, and the size of inclusions is 10
A copper alloy for electronic materials excellent in strength and conductivity, characterized in that the number of inclusions having a size of 5 μm or less and having a size of 5 to 10 μm is less than 50 / mm ^{2 in} a cross section parallel to the rolling direction. 5. A material obtained by heating an ingot at a temperature of 800 ° C. or higher and lower than 900 ° C. for 1 hour or longer, and then hot rolling at a hot rolling end temperature of 650 ° C. or higher, and then performing heat treatment and rolling. , 1 to 10 at material temperature of 300 to 650 ℃
The aging process of time is performed, The claim 1 characterized by the above-mentioned.
A method for producing a copper alloy for electronic materials according to any one of the above.