TWI509090B - Copper alloy plate, and with its high current with electronic components and thermal electronic components - Google Patents

Description

Copper alloy plate, electronic component with high current and electronic component for heat dissipation

The present invention relates to a copper alloy excellent in heat dissipation, electrical conductivity and drawability, and in particular to an electronic component suitable for terminals, connectors, relays, switches, sockets, bus bars, lead frames, etc. It is a copper alloy used for heat-dissipating parts and high-current parts used in smart phones or personal computers.

In electrical/electronic equipment such as smart phones, tablets, and personal computers, components for obtaining electrical connections such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and the like are assembled.

In recent years, with the miniaturization of smart phones, tablet computers, and personal computers, there is a tendency for heat storage during power-on of liquid crystal components or IC chips in an electric/electronic device. Since the state of heat storage is large, thermal damage to the IC chip or the substrate is large, and heat dissipation of the heat dissipating component becomes a problem.

Previously, the heat-dissipating parts in electric/electronic machines such as smart phones, tablets, and personal computers have been mainly used in Worthite iron-based stainless steel and pure aluminum. For a heat dissipating component (liquid crystal frame) attached to a liquid crystal such as a smart phone or a tablet, in addition to requiring high heat dissipation, the strength of the structure and the bending property or drawing workability required for fixing the liquid crystal are required.

Although the Worstian iron-based stainless steel has good bending property and drawing workability, it has low thermal conductivity, and in order to compensate for this disadvantage, an expensive heat-conductive sheet or the like is used in combination. Therefore, the unit price of the heat dissipating component is increased. On the other hand, although pure aluminum and aluminum alloys have good bendability and drawability, thermal conductivity and structure The strength of the body is insufficient.

It is known that thermal conductivity is proportional to electrical conductivity, and as an alloy having a relatively high electrical conductivity and strength, a material in which Zr or Ti is added to Cu is known. As a material having high conductivity and relatively high strength, for example, CDA (Copper Development Association) is registered with C15100 (0.1% by mass Zr-remaining Cu), C15150 (0.02% by mass Zr-remaining Cu). , C18140 (0.1% by mass Zr-0.3% by mass Cr-0.02% by mass Si-remaining Cu), C18145 (0.1% by mass Zr-0.2% by mass Cr-0.2% by mass Zn-remaining Cu), C18070 (0.1% by mass Ti-) An alloy such as 0.3 mass% Cr-0.02 mass% Si-remaining Cu), C18080 (0.06 mass% Ti-0.5 mass% Cr-0.1 mass% Ag-0.08 mass% Fe-0.06 mass% Si-remaining Cu).

However, it is known that a copper alloy in which Zr or Ti is added to Cu (hereinafter referred to as a Cu-Zr-Ti alloy) has high strength and heat conduction characteristics, but does not satisfy the required bending property or drawing processability, and sometimes Both are not satisfied.

Therefore, if the bending property and the drawing workability can be improved while maintaining the strength and electrical conductivity of the Cu-Zr-Ti alloy, it can be said that it is extremely industrially significant.

Accordingly, an object of the present invention is to provide a copper alloy which has high strength, high electrical conductivity, and excellent drawability and bending workability.

The present inventors have found that in the Cu-Zr-Ti alloy, by controlling the value of the plate thickness anisotropy, the drawability and the bending workability can be improved, and the value of the plate thickness anisotropy is obtained from the surface. The Rankford value is measured in the three directions.

Based on the above knowledge, the following invention was completed.

The copper alloy sheet of the present invention contains a total of 0.01 to 0.50% by mass of one or two of Zr and Ti, and the balance is composed of copper and unavoidable impurities, and has a conductivity of 70% IACS or more and a 0.2% guarantee of 350 MPa or more. The stress, and the Ranke anisotropy defined by (r ₀ +r ₉₀ +2×r ₄₅ )/4 by the Rankord values r ₀ , r ₉₀ , r ₄₅ in the direction of the parallel, right angle, and 45° of the calendering is 1.2. the above.

Preferably, the minimum bending radius/plate thickness (MBR/t) of the rolling parallel direction (GW direction) and the rolling orthogonal direction (BW direction) in the bending test of the copper alloy sheet according to the present invention can be expressed as MBR/t≦2.0. By. Furthermore, it is preferable that the copper alloy sheet of the present invention contains at least one element selected from the group consisting of Ag, Co, Ni, Cr, Mn, Mg, Si, Zn, Sn, and B in an amount of 2% by mass or less.

The high-current electronic component and the heat-dissipating electronic component of the present invention each have any of the above-described copper alloy sheets.

According to the present invention, it is possible to provide a copper alloy sheet having both high strength, high electrical conductivity, and excellent drawability. The copper alloy sheet is suitable for use as a raw material for electronic components such as terminals, connectors, switches, sockets, relays, bus bars, and lead frames, and is suitable for heat-dissipating parts and high currents used in smart phones or personal computers. Copper alloy sheet for the use of parts.

Hereinafter, embodiments of the present invention will be described.

(characteristic)

The object of the present invention is to adjust the conductivity of the copper alloy sheet, the 0.2% proof stress, the MBR/t of the W bending test, and the thickness anisotropy obtained from the Rankford value to 70% IACS or more, respectively. 350 MPa or more, 2.0 or less, and 1.2 or more. When the electrical conductivity is 65% IACS or more, the thermal conductivity is good, and good heat dissipation can be ensured. Moreover, when the 0.2% proof stress is 350 MPa or more, it has the strength required as a raw material of a structural material. If the MBR/t is 2.0 or less, it is considered to have good bendability. Further, when the thickness anisotropy obtained from the Rankford value is 1.2 or more, it is considered to have the desired drawability.

The copper alloy sheet of the present invention having the above characteristics is suitable for use in electronic parts for heat dissipation.

Here, the conductivity is measured in accordance with JIS H0505, and it is preferable to set the conductivity to 75% IACS or more.

The 0.2% guaranteed stress is measured in accordance with JIS Z2201. From the viewpoint of ensuring strength, it is preferred to have a 0.2% proof stress of 450 MPa or more.

More preferably, the ratio of the minimum bending radius to the sheet thickness (MBR/t) measured in accordance with JIS H3130 is 1.5 or less.

(alloy concentration)

The Cu-Zr-Ti alloy plate according to the embodiment of the present invention contains one or two of Zr and Ti in a total amount of 0.01 to 0.50% by mass, and the total content of Zr and Ti is preferably set to 0.015 to 0.3% by mass. Good is 0.02~0.20% by mass. When the total of one or both of Zr and Ti is less than 0.01% by mass, it is difficult to obtain a tensile strength of 350 MPa or more and a stress relaxation ratio of 15% or less. When the total of one or both of Zr and Ti exceeds 0.5% by mass, it is difficult to produce an alloy due to hot rolling cracking or the like. When Zr is added, it is preferable to adjust the addition amount to 0.01 to 0.45 mass%, and when Ti is added, it is preferable to adjust the addition amount to 0.01 to 0.20 mass%. When the amount added is less than the lower limit, the 0.2% proof stress may not reach 350 MPa, and if the amount exceeds the upper limit, the conductivity or the manufacturability may be deteriorated.

In order to improve the strength and the heat resistance, the Cu-Zr-Ti alloy may contain one or more of Ag, Co, Ni, Cr, Mn, Zn, Mg, Si, Sn, and B. However, if the amount added is too large, there is a decrease in electrical conductivity and less than 70% IACS, or the manufacturing property of the alloy is deteriorated. In this case, the amount of addition is 1.0% by mass or less, and more preferably 0.5% by mass or less, based on the total amount. Moreover, in order to obtain the effect by addition, it is preferable to set the addition amount to 0.001 mass % or more in total amount.

(thickness)

The thickness of the product is preferably 0.05 to 2.0 mm. If the thickness is too small, sufficient heat dissipation cannot be obtained, and thus it is not suitable as a raw material for electronic components for heat dissipation. On the other hand, if the thickness is too large, drawing processing and bending processing become difficult. In this regard, the preferred thickness is 0.08 to 1.5 mm. When the thickness is in the above range, it is possible to obtain excellent heat dissipation properties and good bending workability.

(drawing processability)

A tensile strain of 2.5% was applied to the parallel, right angle, and 45° directions of the test piece, and the Rankford values of each direction, that is, r ₀ , r ₉₀ , and r ₄₅ , were determined from the dimensional changes in the length and width directions of the test piece. Calculate the plate thickness anisotropy defined by r = (r ₀ + r ₉₀ + 2 × r ₄₅ ) / 4. It is known that the larger the usual value of r, the better the drawability. Further, in general, the r of the copper product is about 0.8 to 1.1, and by adjusting the value to 1.2 or more, excellent drawability can be obtained.

Here, the Rankorford value is defined by JIS Z2254, and is measured in accordance with JIS Z2254 when measuring each of the above-mentioned Rankford values r ₀ , r ₉₀ , and r ₄₅ . Among them, in order to maintain the strength required as a structural material, the present invention has a low elongation and a load strain of 2.5%.

In order to obtain more excellent drawability, it is preferable to set the plate thickness anisotropy r to 1.25 or more.

(Production method)

Hereinafter, an example of a suitable method for producing a copper alloy sheet of the present invention will be described.

The electrolytic copper or the like which is a raw material of pure copper is melted, and the oxygen concentration is lowered by carbon deoxidation or the like, and then one or two kinds of Zr and Ti, and other alloying elements as necessary, are added to cast a casting having a thickness of about 30 to 300 mm. ingot. After the ingot is formed into a plate having a thickness of about 3 to 30 mm by hot rolling, cold rolling and recrystallization annealing are repeated, and finally processed into specific by cold rolling. The thickness of the product is finally subjected to relaxation annealing.

In the recrystallization annealing, part or all of the rolled structure is recrystallized. Further, by annealing under appropriate conditions, Zr, Ti, and the like are precipitated, and the electrical conductivity of the alloy is increased. In the recrystallization annealing before the final cold rolling, the average crystal grain size of the copper alloy sheet was adjusted to 50 μm or less. When the average crystal grain size is too large, it becomes difficult to adjust the tensile strength of the product to 350 MPa or more, and the sheet thickness anisotropy obtained from the Rankford value is <1.2. Preferably, the average crystal grain size is 40 μm or less.

The conditions of the recrystallization annealing before the final cold rolling are determined based on the target crystal grain size after annealing and the target product conductivity. Specifically, the batch furnace or the continuous annealing furnace may be used, and the furnace temperature may be 350 to 800 ° C for annealing. For the batch furnace, it is advisable to adjust the heating time in the range of 30 minutes to 30 hours at a furnace temperature of 350 to 600 °C. For the continuous annealing furnace, the heating time can be appropriately adjusted in the range of 5 seconds to 10 minutes at an oven temperature of 450 to 800 °C. In general, if annealing is performed at a lower temperature for a longer period of time, a higher conductivity can be obtained with the same crystal grain size.

In the final cold rolling, the material is repeatedly passed between a pair of calender rolls and gradually processed into a target sheet thickness. The total degree of processing of the final cold rolling and the degree of processing per pass are controlled.

The total degree of work R (%) can be obtained from R = (t _{0 -} t) / t ₀ × 100 (t ₀ : plate thickness before final cold rolling, t: plate thickness after final cold rolling). Further, the degree of processing K (%) per pass means the plate thickness reduction rate when passing through the calender roll once, which can be K = (T _{0 -} T) / T ₀ × 100 (T ₀ : before passing through the calender roll The thickness, T: the thickness after rolling the roll) was determined.

The total processing degree R is set to 40 to 99%. If R is too small, it is difficult to adjust the 0.2% proof stress to 350 MPa or more, and if R is too large, cracks may occur at the edge of the rolled material. From this point of view, the total workability R should be set to 45 to 99.

The relaxation annealing of the present invention is carried out using a continuous annealing furnace. Batch furnace In this case, since the material is heated in a state in which the coil is wound, the material is plastically deformed during heating to cause warpage in the material. Therefore, the batch furnace is not suitable for the relaxation annealing of the present invention.

For the relaxation annealing after rolling, the tension applied to the material in the continuous annealing furnace is adjusted to 1 to 5 MPa, more preferably 1 to 4 MPa. When the tension is too large, the plate thickness anisotropy r is lowered, and it becomes difficult to adjust to 1.2 or more. On the other hand, if the tension is too small, the material will contact the furnace wall when passing through the annealing furnace, and scratches or the like may be generated on the surface or the edge of the material, which may cause a decrease in productivity.

In the continuous annealing furnace, the furnace temperature is set to 300-700 ° C, the heating time is suitably adjusted in the range of 5 seconds to 10 minutes, and the 0.2% guaranteed stress (σ) after the relaxation annealing is adjusted to be relative to the relaxation annealing. The former 0.2% guaranteed stress (σ ₀ ) is lower than the value of 10 to 50 MPa, preferably 15 to 45 MPa lower. Thereby, the lower elongation is increased in the final cold rolling, and the bendability is improved.

One of the features of the present invention is to improve the drawing processability by imparting the characteristics of the relaxation annealing and the thickness anisotropy r≧1.2 obtained from the Rankford value to the Cu-Zr-Ti alloy. Bending workability; if the manufacturing conditions for achieving these characteristics are shown, it is as follows.

a. In the relaxation annealing, adjust to (σ _{0 -} σ) = 10 ~ 50MPa.

b. Adjust the internal tension of the furnace during relaxation annealing to 5 MPa or less.

c. The total processing degree of the fine rolling is less than 99%.

[Examples]

In the following, the embodiments of the present invention are shown in conjunction with the comparative examples, but the embodiments are provided to better understand the present invention and its advantages, and are not intended to limit the present invention.

After the alloying element was added to the molten copper, it was cast into an ingot having a thickness of 200 mm. The ingot was heated at 950 ° C for 3 hours, and a plate having a thickness of 15 mm was formed by hot rolling. Using a grinder After grinding and removing the scale on the surface of the hot rolled sheet, annealing and cold rolling are repeated, and the thickness of the product is processed in the final cold rolling. Finally, a relaxation annealing is performed using a continuous annealing furnace.

Regarding the final cold rolling annealing (final recrystallization annealing), the batch furnace is used, the heating time is set to 5 hours, and the furnace temperature is adjusted in the range of 300 to 700 ° C, so that the crystal grain size after annealing is The conductivity changes. Regarding the measurement of the crystal grain size after annealing, the cross section perpendicular to the rolling direction was subjected to mirror polishing, chemical etching, and the average crystal grain size was determined by a cutting method (JISH 0501 (1999)).

In the final cold rolling, the total processing degree and the degree of processing per pass are controlled. Further, the 0.2% proof stress of the final cold rolled material was determined.

In the relaxation annealing using a continuous annealing furnace, the furnace temperature was set to 500 ° C, and the heating time was adjusted between 1 second and 15 minutes, and the 0.2% proof stress after annealing was varied. Moreover, various changes in the tension applied to the material in the furnace are caused. Furthermore, for some materials, the relaxation annealing is omitted.

The following measurements were made for the materials in the manufacturing process and the materials after the relaxation annealing.

(ingredient)

The alloying element concentration of the material after relaxation annealing was analyzed by ICP-mass spectrometry.

(0.2% guaranteed stress)

For the material after the final cold rolling and the relaxation annealing, the test piece No. 13B specified in JIS Z2241 is used in the direction in which the stretching direction is parallel to the rolling direction, and the tensile test is performed in parallel with the rolling direction in accordance with JIS Z2241. 0.2% guaranteed stress.

(Conductivity)

The material after the self-relaxation annealing was subjected to a test piece in such a manner that the longitudinal direction of the test piece was parallel to the rolling direction, and the electrical conductivity at 20 ° C was measured by a four-terminal method in accordance with JIS H0505.

(plate thickness anisotropy)

JIS13B as specified in JIS Z2241 is taken in the parallel, right angle, and 45° direction of the test piece. Test piece. Using a tensile tester, a tensile strain of 2.5% was applied to the test pieces, respectively, and the plate thickness anisotropy was calculated.

(MBR/t)

A short strip test piece having a width of 10 mm × a length of 30 mm was produced and subjected to a W bending test (JIS H3130). The direction in which the test piece was taken was set to the rolling parallel direction (GW) and the rolling right angle direction (BW), and the ratio of the minimum bending radius MBR (Minimum Bend Radius) and the sheet thickness t, MBR/t, which did not cause cracking, was evaluated.

The evaluation results of these are shown in Table 1. In addition, in the content shown in Table 1, the expression "<5" of the crystal grain size after the final recrystallization annealing includes the case where all the calendered structures are recrystallized, the average crystal grain size thereof is 5 μm or less, and calendering. Both of the cases where recrystallization occurs in only part of the organization.

As is apparent from the contents shown in Table 1, in the copper alloy sheets of Inventive Examples 1 to 23, since the total concentration of Zr and Ti is adjusted to 0.01 to 0.50% by mass, the total degree of final rolling is 99% or less. The tension of the relaxation annealing is 1 to 5 MPa and is within the specified range. Therefore, all of them satisfy the 0.2% guaranteed stress of 350 MPa or more, the electrical conductivity is 70% or more, and the plate thickness anisotropy r is 1.2 or more, and heat dissipation, strength, and processing are obtained. Good material.

In Comparative Example 1, the relaxation annealing was not performed, the plate thickness anisotropy was less than 1.2, the drawability was poor, and the bending workability of BW was poor. In Comparative Examples 2 and 3, although the relaxation annealing was performed, the tension exceeded the upper limit of the predetermined range, the sheet thickness anisotropy was less than 1.2, and the drawability was poor.

In Comparative Example 4, the 0.2% proof stress caused by the relaxation annealing was too small, the sheet thickness anisotropy was less than 1.2, the drawability was poor, and the bending workability on GW and BW was poor. Regarding Comparative Example 5, 0.2% of the relaxation stress was ensured that the amount of reduction was too large, the plate thickness anisotropy was less than 1.2, the drawability was poor, and the endurance after the relaxation force annealing was less than 350 MPa, and the strength was insufficient.

In Comparative Example 6, since the added concentration of Zr was too low, the endurance was less than 350 MPa, and the strength was insufficient. Regarding Comparative Example 7, the added concentration of Zr was excessive, the electrical conductivity was less than 70%, and the heat dissipation was poor.

In Comparative Example 8, since the crystal grain size at the time of recrystallization annealing exceeded 50 μm, the sheet thickness anisotropy was less than 1.2, the drawability was poor, and the strength was insufficient.

In Comparative Example 9, the total workability of the final press delay was less than 40%, so the strength was insufficient.

Claims (6)

A copper alloy plate containing a total of 0.01 to 0.50% by mass of one or two of Zr and Ti, the remainder being composed of copper and unavoidable impurities, having a conductivity of 70% IACS or more, and a 0.2% guaranteed stress of 350 MPa or more And the plate thickness anisotropy defined by (r ₀ +r ₉₀ +2×r ₄₅ )/4 by the Lankford value r ₀ , r ₉₀ , r _{45 of the} rolling parallel, right angle, 45° directions The sex is 1.2 or more. A copper alloy sheet according to claim 1 which contains one or both of Zr and Ti in a total amount of 0.015 to 0.3% by mass. For example, the copper alloy sheet of claim 1 or 2, wherein the minimum bending radius/plate thickness (MBR/t) of the rolling parallel direction (GW direction) and the rolling orthogonal direction (BW direction) in the W bending test can be expressed. For MBR/t≦2.0. The copper alloy sheet according to claim 1 or 2, which contains at least one selected from the group consisting of Ag, Co, Ni, Cr, Mn, Mg, Si, Zn, Sn, and B in an amount of 2% by mass or less element. A high-current electronic component having a copper alloy plate of the first or second patent application scope. A heat-dissipating electronic component having a copper alloy plate of the first or second patent application scope.