JP4838524B2 - Copper alloy material for electrical and electronic parts - Google Patents

Description

  The present invention relates to a copper alloy material for electrical and electronic parts used for electronic parts of mobile phones and personal computers, for example, and more particularly to a copper alloy material for electrical and electronic parts that require reflow soldering many times. is there.

  The applicant has conventionally provided this kind of copper alloy material for electric and electronic parts, and the copper alloy improved from CDA72500 (9% Ni-2.3% Sn) is also used for transistors. Has been. However, since this copper alloy material contains 8% or more of solid-dissolved Ni, the Cu-Sn intermetallic compound (Cu-Sn alloy layer) when plated with Sn is likely to be in an acicular form, and the alloy layer Since the growth rate was increased, the reflow solderability tended to deteriorate.

  In addition, due to the recent trend toward lead (Pb) -free solder alloys and the increase in the number of reflows, the problem of reflow solderability (reflow resistance) has begun to attract attention. Furthermore, in the case of electrical and electronic parts (for example, for transistors, particularly for minitransistors), resin burr peeling properties that occur during resin molding in the assembly process are also required.

  The present invention has been made in view of the above-mentioned problems, and its purpose is not only reflow resistance required in the manufacturing process of electrical and electronic parts, but also excellent resin burr peelability and bending workability. The present invention provides a copper alloy material for electrical and electronic parts that is excellent in tensile strength and electrical conductivity.

In order to achieve the above object, a copper alloy material for electrical and electronic parts according to the present invention (Claim 1) contains 1.5 to 2.0 % (mass%, the same applies hereinafter) of solid solution Ni, Ni The content of is 1.8 to 3.2%, and further contains 1.5% or less (not including 0%) of Si, with the balance being Cu and inevitable impurities. The copper alloy material may further contain 8.0% or less of Sn (Claim 2), and may further contain one or both of 2.0% or less of Zn and 0.5% or less of Mg. (Claim 3) and may further contain 0.020% or less of Mn (Claim 4).

  According to the copper alloy material for electric and electronic parts according to the present invention, it is required as a material for electric and electronic parts such as mechanical properties such as tensile strength and electrical conductivity, resin burr peelability and bending workability, particularly as a transistor material. It is possible to meet the demand for improvement in reflow resistance accompanying the recent Pb-free operation without impairing the properties to be achieved.

  The inventors of the present invention indicate that the reflow solderability tends to be deteriorated when 8% or more of solid solution Ni is contained like a copper alloy material improved by CDA72500 (9% Ni-2.3% Sn). After finding out, the cause was investigated. As a result, the following was found. That is, the soldering in the manufacturing process of the electrical / electronic component generally joins the substrate and the lead by reflow soldering. In the conventional soldering, reflow treatment using Sn—Pb solder having a low melting point was performed several times. However, with the recent trend toward Pb-free and downsizing of electric and electronic parts, high temperature and many reflow processes have been performed. Such reflow treatment at high temperature and many times promotes alloying of solder and material (generation of intermetallic compounds). This alloying tends to accelerate as the amount of dissolved Ni contained in the material increases.

  Then, from the above investigation results, the amount of Ni dissolved in the present invention is 0.5 to 3.5%, thereby improving the reflow resistance and the resin burr peelability. If the amount of Ni is less than 0.5%, the resin burr peelability is poor, and if it exceeds 3.5%, the reflow resistance is adversely affected. The reason why the resin burr peelability deteriorates when the solid solution Ni content is less than 0.5% is not clear but is considered as follows. That is, the resin adhesion usually improves as the copper alloy material is closer to pure copper (no other elements are contained) (resin burr peelability is worsened). In particular, solid solution Ni seems to have a larger contribution to resin adhesion than Sn and Zn. If a large amount of this solid solution Ni is contained, the oxide film when heated is thinner than the pure copper, and this film is thin. This is considered to deteriorate the adhesiveness with the resin (improve the resin burr peelability).

Hereinafter, the reason for limiting the content of components other than solute Ni will be described.
If Si is contained in an amount of 1.5% or more, the tensile strength becomes too high, and this adversely affects bending workability.

  Sn does not affect the reflow resistance, but has the effect of improving the resin burr peelability, and is preferably added at 8.0% or less. This Sn greatly contributes to the tensile strength due to solid solution strengthening, but if it exceeds 8.0%, the tensile strength becomes too high, so 8.0% or less is suitable.

  Zn, like Sn, greatly contributes to the tensile strength by solid solution strengthening, but if it exceeds 2.0%, the tensile strength becomes too high, so 2.0% or less is suitable.

  When Mg is contained in an amount exceeding 0.5%, the hot workability is inferior, so 0.5% or less is suitable.

  Mn, like Mg, improves the hot workability, but if it is contained in an amount of 0.02% or more, the strength increases, and therefore the bending workability deteriorates.

  If Pb is contained in an amount of 0.010% or more, there is a concern that cracking may occur during hot working, and it is difficult to obtain a predetermined strength.

In general, it is known that bending workability is impaired when the tensile strength increases. Therefore, in the present invention is not particularly limited, tensile preferably be prepared so that 560~620N / mm ² strength, tensile strength formability deteriorates at 560N / mm ² or less, 620N When it exceeds / mm ² , there is a concern that the bending workability is deteriorated. In addition, since the electrical conductivity also affects the resistance weldability when manufacturing electrical and electronic parts, it is preferable that the electrical conductivity be 35% IACS or less. If the electrical conductivity exceeds 35% IACS, the resistance weldability is deteriorated. Is concerned.

Next, examples of the present invention will be described in comparison with comparative examples.
Example No. of the present invention shown in Table 1 using a small electric furnace. 1-8 (however, No. 2 , 3 are reference examples) and comparative example No. Copper alloys having respective component compositions of 9 to 18 were melted in the atmosphere under charcoal coating, and the molten metal was cast to produce an ingot having a thickness of 50 mm, a width of 80 mm, and a length of 180 mm. Each of the front and back surfaces of the ingot produced was chamfered by 5 mm. Nos. 1, 4, 6, 7, 8, 14, 15, 16, 17, 18 are 950 ° C. Nos. 2, 10 and 12 are 900 ° C. No. 3 is 800 ° C. For Nos. 5 and 9, 930 ° C. No. 11 is 965 ° C. No. 13 was each hot-rolled at 725 ° C. to obtain a plate material having a thickness of 15 mm.

  The plate material having a thickness of 15 mm obtained above was further chamfered on the front and back surfaces of the plate material, respectively subjected to the following treatment, and cold-rolled to obtain a plate material having a thickness of 0.25 mm.

No. of the present invention. 1, 4 to 8 and Comparative Examples 9 and 14 to 18 were subjected to a solution treatment at 750 ° C. before cold rolling. Incidentally, cold may be rolled after controlling the Ni solid solution amount perform batch annealing instead of the solution treatment. When solution treatment and batch annealing are performed, the surface oxidation scale is 25% sulfuric acid + 2.8% hydrogen peroxide + fluorine solution of 8000-10000ppm KFHF (potassium hydrogen fluoride) in an aqueous solution diluted twice. It must be removed by pickling and polishing.

Reference Example No. 2, 3 and Comparative Examples 10 to 13 were annealed for 20 seconds at an appropriate treatment temperature in the range of 500 ° C. to 900 ° C. before cold rolling, and then pickled and polished with 20 vol% sulfuric acid water. The surface oxide scale was removed.

  Each specimen prepared as described above with a plate thickness of 0.25 mm was further subjected to low-temperature annealing at 350 ° C. for 20 seconds, and then 25% sulfuric acid + 2.8% hydrogen peroxide + fluorine content was 8000 to 8000, respectively. The oxidized scale on the surface was removed by pickling and polishing using an aqueous solution obtained by diluting 10000 ppm KFHF twice and 20 vol% sulfuric acid water. In addition, No. For No. 11, low temperature annealing was omitted.

  Next, the Ni solid solution amount, tensile strength, electrical conductivity, reflow resistance, resin burr peelability, and bending workability were investigated in the following manner based on each specimen having a thickness of 0.25 mm obtained above. .

The amount of Ni solid solution is obtained by dissolving the plate material obtained above in 25 vol% HNO ₃ aqueous solution, removing Ni-Si compounds as precipitates with filter paper, and then analyzing the Ni amount by ICP emission analysis. It was.

  Tensile strength and electrical conductivity were measured by measuring the tensile strength in the rolling parallel direction with a JIS No. 5 test piece with the longitudinal direction of the plate material obtained above being parallel to the rolling direction. The conductivity was measured based on JISH0505.

Reflow resistance is Pb-free after the surface of the plate obtained above is cut to 100 mm x 100 mm, the surface is cleaned by electrolytic degreasing (4 A / dm ² x 60 seconds) and 20% sulfuric acid pickling for 5 seconds. About 6 μm of Sn—Bi plating, which is solder plating, was applied. Then, the mixture was heated 250 ° C. × 75 seconds at an N ₂ gas atmosphere, after cutting a section with a microtome, the cut surface was observed by a surface SEM, it is observed the thickness of the resulting Sn-Cu alloy layer. The materials having an average thickness of the alloy layer of up to 6 μm were evaluated as “x” when the material was 3 μm to 6 μm, and “◯” when the material was 3 μm or less.

  The resin burr peelability was obtained by cleaning the surface of the plate material obtained above, heating each plate material at 280 ° C. for 10 seconds with a hot plate, mold mold 180 ° C., resin injection pressure 6.8 MPa, injection time Resin molding was performed under the condition of 20 seconds. As the resin, a commercially available resin for semiconductor molding was used. The shear strength of the molded material was measured with a shear tester to evaluate the peelability between the material and the resin. The resin peel strength was evaluated with 0.5 to 3.0 kgf as ◯, 3.0 to 4.0 kgf as Δ, and 4.0 kgf or more as x.

  The bending workability was evaluated by a W bending test using a strip test piece having a width of 10 mm. When the bending radius is R and the plate thickness is t, and R / t = 2, evaluation is good (no cracks and no rough skin), good skin is △, rough skin is large and cracks are generated. What was present was evaluated as x.

About the result investigated by the said point, Ni solid solution amount is shown in Table 1, and others are shown in Table 2, respectively.

As is clear from Table 1 and Table 2 above, Example No. of the present invention. The alloys of Nos. 1 to 8 (Nos. 2 and 3 are reference examples) satisfy the mechanical properties of a tensile strength of 560 to 620 N / mm ² and an electrical conductivity of 35% IACS or less. Furthermore, it is also excellent in reflow resistance, resin burr peelability and bending workability.

  Comparative Example No. Nos. 9, 10, and 12 have a small amount of solid solution Ni of less than 0.5% (0.4%, 0.22%), and therefore the resin burr peelability is poor. Comparative Example No. No. 11 contains a large amount of solute Ni as 4%, so that the alloy layer grows quickly during soldering and the reflow resistance is poor. Comparative Example No. No. 13 contains a large amount of Sn at 9.0%, so that the tensile strength becomes too high and the bending workability is also inferior.

Comparative Example No. Nos. 14 to 18 are comparative example No. 14 although the solid solution Ni amount satisfies the present invention. No. 14 is 2.0% Si, Comparative Example No. 15 is 2.0% Zn, Comparative Example No. 16 is 0.7% Mg, Comparative Example No. No. 17 has Mn of 0.10%, Comparative Example No. No. 18 contains a large amount of Pb of 0.10%, so that the tensile strength is high. Further, since the tensile strength is high, bending workability cannot be obtained sufficiently. Comparative Example No. Since No. 16 contains a large amount of Mg as 0.7%, the hot workability is also inferior.

Claims (4)

1.5 to 2.0 % (mass%, the same shall apply hereinafter) of solid solution Ni, the Ni content is 1.8 to 3.2%, and further 1.5% or less (including 0%) include Si of not), electric and electronic parts for copper alloy material balance being composed of Cu and unavoidable impurities.   The copper alloy material for electrical and electronic parts according to claim 1, further comprising 8.0% or less of Sn.   The copper alloy material for electrical and electronic parts according to claim 1 or 2, further comprising one or both of 2.0% or less of Zn and 0.5% or less of Mg.   Furthermore, the copper alloy material for electrical and electronic parts according to any one of claims 1 to 3, further comprising 0.020% or less of Mn.