JP5085908B2 - Copper alloy for electronic materials and manufacturing method thereof - Google Patents

Description

  The present invention relates to a copper alloy for electronic materials having an excellent balance of strength, conductivity and bending workability suitable as a material used for terminals, connectors, switches and relays.

It is known that Cu—Ni—Si-based alloys are precipitation-type copper alloys, and Ni—Si-based intermetallic compounds are known to increase in strength and conductivity due to precipitation in the parent phase. Similarly, Si and a compound are formed in a copper alloy to improve mechanical strength (Patent Document 1). It is known that this Cu—Co—Si alloy is slightly better in mechanical strength and conductivity than the Cu—Ni—Si alloy (Patent Document 2 “0022”).
On the other hand, in the Cu—Cr—Si based alloy, it is reported that Cr forms a compound with Si similarly to Ni and Co, or precipitates as a single Cr in the parent phase to increase the strength (Patent Document 3 No. 3). Page 3).
JP 2005-532477 A Japanese Patent Application Laid-Open No. 11-222641 JP 62-180025 A

However, since the temperature for solution treatment (the temperature at which Co and Si are dissolved) increases in the Cu-Co-Si alloy, it is difficult to completely perform solution treatment, and the desired characteristics are obtained. It cannot be obtained (Patent Document 1). Therefore, there have been few examples of completely replacing with conventional Co.
On the other hand, in the Cu—Cr—Si based alloy, Cr easily forms a carbide compound (Cr—C) that does not contribute to strength, and it is difficult to stably obtain desired strength. Further, even if a coarse Cr-based compound that does not contribute to strength is formed, desired characteristics cannot be obtained. Furthermore, when Cr—C is formed, Cr bonded to Si is reduced, so that Si that could not be bonded to Cr is excessively dissolved in the matrix phase and the conductivity is remarkably lowered.

The present invention achieves a copper alloy for electronic materials that is superior in strength and electrical conductivity by adopting the following configuration.
(1) Co: 1.00-2.50% by mass, Si: 0.20-0.70% by mass, composed of the balance Cu and unavoidable impurities, and the mass concentration ratio of Co and Si (Co / A copper alloy for electronic materials, wherein the Si ratio) is 3.5 ≦ Co / Si ≦ 5 and the electrical conductivity is 55% IACS or more.
(2) Co: 1.00-2.50% by mass, Cr: 0.05-0.50% by mass, Si: 0.20-0.70% by mass, comprising the remainder Cu and inevitable impurities A copper alloy for electronic materials, wherein the mass concentration ratio of Co and Si (Co / Si ratio) is 3.5 ≦ Co / Si ≦ 5 and the electrical conductivity is 60% IACS or more.
(3) Co: 1.00-2.50% by mass, Cr: 0.05-0.50% by mass, Si: 0.20-0.70% by mass, and carbon as an inevitable impurity is 50 ppm. It is composed of the remainder Cu and inevitable impurities, the mass concentration ratio of Co and Si (Co / Si ratio) is 3.5 ≦ Co / Si ≦ 5, and the conductivity is 60% IACS or more. A copper alloy for electronic materials.
(4) Further, 0.001 to 0.300% by mass of at least one selected from the group consisting of Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr, Al, Fe, Zn, and Ag. The copper alloy for electronic materials as described in the above item.
(5) The hot-rolling and the cold-rolling are performed after the melt casting, and the heat treatment is performed at 700 ° C. to 1050 ° C. before the final cold rolling, followed by cooling at 10 ° C. or more per second. Of producing a copper alloy for electronic materials.

Co and Si addition amount:
Co forms an intermetallic compound with Si. The Cu—Co—Si based copper alloy can achieve higher conductivity while maintaining the strength as compared with the Cu—Ni—Si based copper alloy. If the addition amount of Co and Si is less than Co: 1.00% by mass and / or Si: less than 0.20% by mass, a desired strength cannot be obtained, and Co exceeds 2.50% by mass and / or Si: 0. When it exceeds 70 mass%, the strength can be increased, but the electrical conductivity is remarkably lowered, and the hot workability is further deteriorated. Therefore, the addition amounts of Co and Si were set to Co: 1.00 to 2.50 mass% and Si: 0.20 to 0.70 mass%. Preferably, they are Co: 1.50-2.20 mass%, Si: 0.35-0.50 mass%.

Co / Si ratio:
The characteristics can be further improved by bringing the weight ratio of Co and Si in the alloy closer to the concentration of Co ₂ Si which is an intermetallic compound. When the weight concentration ratio is Co / Si <3.5, the conductivity is lowered because the Si concentration is high. On the other hand, in the case of Co / Si> 5, since the Co concentration is high, the conductivity is remarkably lowered, which is not preferable for an electronic material. Preferably 4.0 <Co / Si <4.5.

Conductivity (EC):
Since the alloy of the present invention is used as a material for terminals, connectors, switches, and relays for vehicles and communication devices that require high conductivity and medium strength, the conductivity is 55% IACS or more, preferably 60%. IACS or more, more preferably 62% IACS or more. The conductivity is a value measured in accordance with JIS H 0505 and expressed in% IACS. If the electrical conductivity is less than 55% IACS, it is not suitable for the use of the alloy for electronic materials which is the object of the present invention. The copper alloy having conductivity according to the present invention can be manufactured by the following manufacturing method.

Cr addition amount:
Cr binds to solute Si that has not been bonded to Co and precipitates as a Cr—Si compound in the parent phase. As a result, the copper purity of the parent phase increases and the conductivity further increases. In addition, the strength increases due to precipitation hardening of the Cr-Si compound. If the amount is less than 0.05% by mass, the effect is small, and if it exceeds 0.50% by mass, the solid solution Cr that does not precipitate in the Cr—Si system or Cr alone increases, so that the conductivity is remarkably reduced. Since the amount of Cr dissolved in the solution is about 0.50% by mass, the Cr not solid-dissolved adversely affects the bending workability. Therefore, the Cr addition amount is set to 0.05 to 0.50 mass%. Preferably it is 0.10-0.30 mass%.

Carbon content:
Cr tends to form Cr—C that does not contribute to strength when carbon is present. If the carbon content in the alloy exceeds 50 ppm, the desired strength cannot be obtained. Furthermore, when Cr—C is formed, Cr that is bonded to Si is reduced. Therefore, Si that cannot be bonded to Cr is excessively dissolved in the matrix and the conductivity is significantly reduced. Therefore, the carbon content is preferably 50 ppm or less, more preferably 30 ppm or less. Carbon control methods include, for example, degreasing so as not to mix carbon in the raw material before melt casting, melt casting under vacuum or inert atmosphere (eg Ar), and charcoal coating during melt casting And not using equipment including carbon-containing members.

Addition of at least one of Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr, Al, Fe, Zn, and Ag reinforces the solid solution strengthening effect because it does not form a compound, and has characteristics. There is an effect to improve. If the addition amount of the above elements is less than 0.001% by mass, there is no effect of addition, and if it exceeds 0.300% by mass, the conductivity decreases. Therefore, the addition amount is 0.001 to 0.300 mass%, preferably 0.01 to 0.10 mass%.
The alloy of the present invention is used as a material for terminals, connectors, switches, and relays for in-vehicle and communication devices that require high conductivity and medium strength, and therefore yield strength (YS: Yield strength). Is preferably 650 MPa or more, more preferably 670 MPa or more.

Production method:
A Cu—Co—Si based alloy has a higher solution temperature than that of a Cu—Ni—Si based alloy, so it is difficult to form a solution. That is, when the amount of Co and Si added (the total amount of Co added and Si added) is less than 2.0% by mass, complete solution treatment can be performed at 1000 ° C. or less, but the amount of Co and Si added is 2.0% by mass. If it is at least%, it requires 1000 ° C. or more for complete solution treatment, and if it is at least 2.5% by mass, it will be 1050 ° C. or more. Since this temperature is close to the melting point and may be dissolved during the solution treatment, it is difficult to make a solid solution of Co and Si addition amounts of 2.5 mass% or more in copper. However, when the solution treatment is incomplete, the strength is reduced but the conductivity is improved. Therefore, in order to produce the copper alloy of the present invention, even when the amount of Co and Si added is 2.5% by mass or more, it is high when heated to a temperature lower than the temperature at which it completely dissolves and then cooled relatively quickly. Conductivity can be obtained. In that case, the desired strength can be ensured by increasing the amount of Co and Si added, and the copper alloy having a good balance between the electrical conductivity and strength of the present invention can be produced.
If the solution temperature is less than 700 ° C., the solution treatment is insufficient, so that the desired strength cannot be obtained, and if it exceeds 1050 ° C., there is a possibility that the solution is completely dissolved. Therefore, the solution temperature is 700 to 1050 ° C., preferably 800 to 900 ° C. and 2.00% to 2.50% when the addition amount of Co and Si is 1.20% by mass or more and less than 2.00% by mass. If less than% by mass. In the case of 900-1000 degreeC and 2.50 mass% or more and less than 3.20 mass%, it is 1000-1050 degreeC.
If the cooling rate after the solution treatment is less than 10 ° C. per second, a coarse Cr-based compound that does not contribute to the strength is precipitated, so that the strength is lowered. Therefore, the cooling rate after heating needs to be 10 ° C. or more per second, preferably 20 ° C. or more per second.
The effect of the present invention can be achieved if the solution treatment is performed before the final cold rolling, and cold rolling or aging treatment may be performed before or after the solution treatment.

Hereinafter, although the conditions according to the present example will be described, the embodiment of the present invention is not limited to the following as long as the effects of the present invention are exhibited.
Sample manufacture:
In a high frequency melting furnace, 2.50 kg of electrolytic copper or oxygen-free copper was dissolved in an alumina or magnesia crucible having an inner diameter of 110 mm and a depth of 230 mm in a vacuum or argon atmosphere. Co, Cr, Si, Mg, Sn, Ag, Zn is added according to the composition of Table 1 or 2, the molten copper temperature is adjusted to 1300 ° C., and then the molten metal is cast using a mold (material: cast iron) 30 × Cast into a 60 × 120 mm ingot. Hot rolling, grinding removal of oxide scale, hot rolling, cold rolling, followed by solution heat treatment that is heated to 700 ° C. to 1050 ° C. and then cooled at 20 ° C. per second, and further cold processed with a working degree of 10 to 60% Rolling and heat treatment at 250 ° C. to 550 ° C. were repeated to form a flat plate having a thickness of 0.10 mm. Various test pieces of the obtained plate material were collected and subjected to physical property evaluation tests.
Physical property evaluation of test piece:
As for the strength, a JIS 13B test piece was prepared using a press so that the tensile direction was parallel to the rolling direction. A tensile test according to JIS Z 2241 was conducted using the test piece, and the yield strength (unit: MPa) of the tensile strength was measured.
The conductivity was measured using a four-terminal method in accordance with JIS H 0505 and displayed in% IACS.
For the bending workability, a strip-shaped sample having a width of 10 mm was used, and a W bending test specified by JISH3110 was performed. The bending direction was set to Good Way and Bad Way (bending radius R / plate thickness t = 1.0).
With respect to the sample after bending, from the surface and cross section of the bent portion, the presence or absence of cracks was observed with an optical microscope, and when no cracks occurred on Good Way and Bad Way, ○, Good Way and Bad Way both or one side The case where cracking occurred was evaluated as x.

Examples of the present invention will be described in Tables 1 to 3 together with Comparative Examples. In addition, "-" in a table | surface represents no addition.
Table 1 shows the results of Cu—Co—Si alloys, and the alloys of Examples 1 to 10 all had excellent strength, conductivity (55% IACS or more), and bending workability.
In Comparative Examples 11 and 12, since the amounts of Co and Si are less than the lower limit or the upper limit of the present invention, respectively, the strength (YS) is low or the conductivity is low and the bending workability is poor. Comparative Examples 13 and 14 have low conductivity because the Co / Si ratio is less than the lower limit or exceeds the upper limit of the present invention, respectively. Comparative Example 15 has low strength because the Co amount and the Co / Si ratio are less than the lower limit of the present invention, respectively. In Comparative Example 16, the electrical conductivity is low because the amount of Co exceeds the upper limit of the present invention. In Comparative Example 17, the Si amount is less than the lower limit of the present invention, and the Co / Si ratio exceeds the upper limit of the present invention, so the conductivity is low. In Comparative Example 18, since the Si amount exceeds the upper limit of the present invention and the Co / Si ratio is less than the lower limit of the present invention, the conductivity is low. In Comparative Examples 19 and 20, since the amount of the third metal such as Mg exceeds the upper limit of the present invention, the electrical conductivity is low and the bending workability may be inferior.
Since Comparative Examples 21 to 31 were performed under the condition that they were sufficiently dissolved in the solution treatment, the electrical conductivity was low and outside the scope of the present invention.

Table 2 shows the results of the Cu—Co—Cr—Si based alloy, and the alloys of Examples 32 to 45 all had excellent strength, electrical conductivity (60% IACS or more), and bending workability.
Reference Examples 46 and 47 correspond to Examples 1 and 2, and since Cr is not added, the conductivity is low as compared with Examples 32-45.
In Comparative Example 48, the amounts of Co and Si are less than the lower limit of the present invention, respectively, so the strength is low. In Comparative Example 49, the amounts of Co and Si exceed the upper limit of the present invention, so the conductivity is low and the bending workability is poor. Comparative Examples 50 and 51 have low electrical conductivity because the Co / Si ratio is less than the lower limit or exceeds the upper limit of the present invention. In Comparative Examples 52 and 53, since the Cr amount is less than the lower limit or the upper limit of the present invention, the conductivity is low, and when the upper limit is exceeded, the bending workability is also inferior. Comparative Example 54 is inferior in strength because the Co amount, Cr amount, and Co / Si ratio are less than the lower limit of the present invention. In Comparative Example 55, the Co amount and the Cr amount exceed the upper limit of the present invention, so the conductivity is low and the bending workability is poor. In Comparative Example 56, since the Cr amount and the Si amount are less than the lower limit of the present invention and the Co / Si ratio exceeds the upper limit of the present invention, the electrical conductivity is low. In Comparative Example 57, the amount of Cr and the amount of Si each exceed the upper limit of the present invention, and the Co / Si ratio is less than the lower limit of the present invention, so the conductivity is low and the bending workability is poor. In Comparative Example 58, the amounts of Co, Cr, and Si are less than the lower limit of the present invention, respectively, and are inferior in strength. In Comparative Example 59, the amounts of Co, Cr, and Si each exceed the upper limit of the present invention, and the electrical conductivity is low and the bending workability is poor. In Comparative Examples 60 and 61, the C amount exceeds the upper limit of the present invention, the electrical conductivity is low, the bending workability is inferior, and the strength may be inferior. In Comparative Examples 62 and 63, since the amount of the third metal such as Mg exceeds the upper limit of the present invention, the electrical conductivity is low and the bending workability may be inferior.
Since Comparative Examples 64-76 were performed on the conditions which fully dissolve in solution treatment, electrical conductivity is low and it is outside the range of the present invention.

  Table 3 shows the results of changing the cooling rate after the solution treatment of Examples 32-34. In Examples 32 ′, 33 ′, and 34 ′, the cooling rate is less than 10 ° C. per second, so the conductivity after the solution treatment increases, and the conductivity of the flat plate obtained after repeated cold rolling and heat treatment also increases. However, the strength decreases. Since Examples 32, 32 ″, 33, 33 ″, 34 and 34 ″ have a cooling rate of 10 ° C. or more per second, the results of all Examples are strength, conductivity (60% IACS or more) and bending. Excellent balance of sex. Accordingly, the cooling rate after the solution treatment is preferably 10 ° C. or more per second.

Claims (5)

Co: 1. It contains 80 to 2.50 mass%, Si: 0.20 to 0.70 mass%, is composed of the balance Cu and inevitable impurities, and the mass concentration ratio of Co and Si (Co / Si ratio) is 3. 5. Copper alloy for electronic materials, wherein 5 ≦ Co / Si ≦ 5 and conductivity is 55% IACS or more. Co: 1. 80 to 2.50% by mass, Cr: 0.05 to 0.50% by mass, Si: 0.20 to 0.70% by mass, composed of the balance Cu and unavoidable impurities, Co and Si A copper alloy for electronic materials, characterized in that the mass concentration ratio (Co / Si ratio) is 3.5 ≦ Co / Si ≦ 5 and the electrical conductivity is 60% IACS or more. Co: 1. 80 to 2.50% by mass, Cr: 0.05 to 0.50% by mass, Si: 0.20 to 0.70% by mass, carbon as an inevitable impurity is 50 ppm or less, and the balance Cu And an inevitable impurity, wherein the mass concentration ratio of Co and Si (Co / Si ratio) is 3.5 ≦ Co / Si ≦ 5 and the electrical conductivity is 60% IACS or more Copper alloy. Furthermore, it contains 0.001 to 0.300 mass% of at least one selected from the group of Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr, Al, Fe, Zn, and Ag. The copper alloy for electronic materials according to any one of claims 1 to 3. Perform hot rolling and cold rolling after melting and casting, and performing heat treatment to cool the heating after every second 10 ° C. or higher before the final cold rolling to 900 to 1050 ° C., either of claims 1 to 4 method for producing a copper alloy for electronic materials according to any.