JP4859238B2 - High strength high conductivity heat resistant copper alloy foil - Google Patents

Description

  The present invention relates to a high-strength, high-conductivity copper alloy foil suitable for use in flexible copper-clad laminates, battery current collectors, and the like.

As a printed wiring board (FPC) used for an electronic circuit of an electronic device, a flexible copper-clad laminate (CCL) in which a copper foil and a resin layer are laminated is known. However, when a resin film is applied to a copper foil or a thermoplastic resin is applied to the CCL, a high tension is applied to the copper foil, so that there is a problem that the copper foil easily breaks as the copper foil becomes thinner. It was.
Further, when a copper foil is used as a current collector for a lithium ion battery, a stress is applied to the copper foil due to a change in volume of the active material that accompanies charging / discharging of the battery, which may cause cracks. As copper foils become thinner, their elongation and tensile strength decrease, so these problems are significant.

Therefore, an alloy system (double phase alloy) in which a second phase is crystallized in a Cu parent phase has been developed as a copper alloy having excellent strength and electrical conductivity and excellent heat resistance. In this alloy, the second phase is dispersed in a fiber shape by being strongly processed and has a strength equal to or higher than that of phosphor bronze and the parent phase is Cu. Therefore, the conductivity is 60% IACS (international annealed copper standard: High electrical conductivity exceeding the ratio of electrical conductivity to annealed standard annealed copper is obtained. As this multiphase alloy system, Cu—Cr, Cu—Fe, Cu—Nb, Cu—W, Cu—Ta, Cu—Ag, and the like are known (for example, see Patent Documents 1 to 8).
In the case of the above prior art, means such as drawing and rolling are used as a processing method for stretching the second phase into a fiber shape. For example, in Patent Documents 1 and 2 below, when a multi-phase alloy is rolled and manufactured, the second phase is sufficiently stretched in the rolling direction to become fibrous, and the rolling proceeds in the direction perpendicular to the rolling direction (the longitudinal direction of the rolled material). It also describes that the strength of the rolled material is also improved.
In general, a multiphase alloy is an alloy that is strengthened by using a composite law or increasing the area of a heterophase interface, and is strengthened by dispersing a second phase in a ribbon shape. Here, the second phase crystallized without dissolving in copper is formed by dispersing in a ribbon shape in the copper matrix by strong processing, so the area of the heterophase interface is increased and the material is strengthened Great effect. For this reason, as the second phase is more dispersed (if the volume fraction is the same, it is finely dispersed), the second phase is more easily stretched, and the degree of processing is increased, so that the strength is increased.

JP-A-6-192801 JP-A-6-279894 JP-A-9-104935 JP-A-9-235633 Japanese Patent Laid-Open No. 9-249925 JP-A-10-53824 Japanese Patent Laid-Open No. 10-140267 Japanese Patent Publication No. 48-34652

However, none of the techniques described in Patent Documents 1 to 8 are suitable for manufacturing a copper foil for a wire or a rolled plate. That is, as the thickness of the foil is reduced, the elongation and tensile strength are reduced, so that it is necessary to further improve the strength of the alloy. In addition, if there are crystallized substances or inclusions in the alloy, pinholes are produced during the production of the foil, or the etching properties of the CCL obtained using this copper foil deteriorate, resulting in a decrease in productivity and circuit. Defects can occur. Therefore, it is necessary to reduce the content and size of the crystallized product and inclusions of the alloy used for the foil.
As described above, the copper alloy used for the foil is required not only to have strength, but also to manage crystallized substances and inclusions. In particular, as electronic devices become smaller and lighter, the FPC circuit's copper wiring width (L) and the distance between copper wirings (S) tend to decrease, and the fine pitch is reduced to about L / S = 20μm / 20μm. It is said that. Along with this fine pitch, the thickness of the copper foil used is expected to be 10 μm or less.

  On the other hand, for example, Patent Documents 5 and 6 disclose an alloy in which Zr is further added to a Cu—Cr two-phase alloy. However, if the amount of Cr or Zr added is too large, the decrease in conductivity increases. At the same time, coarse crystals are produced in the foil, so it is difficult to use this alloy for the foil.

  That is, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-strength, high-conductivity heat-resistant copper alloy foil excellent in strength, conductivity, and heat resistance when formed into a foil. .

As a result of various studies, the present inventors have found that the above problem can be solved by stretching the second phase crystallized in the Cu matrix into a ribbon shape.
In order to achieve the above object, the high-strength, high-conductivity heat-resistant copper alloy foil of the present invention is a two-phase alloy composed of a second phase containing 3% to 15% Ag and a Cu parent phase in mass ratio. It is a rolled foil, which contains one or more first additive elements selected from the group consisting of Cr, Fe and Fe-P in terms of mass ratio in total of 0.1% or more and less than 3%, and the first Precipitates mainly composed of additive elements are precipitated at least in the Cu matrix, the remainder is made of Cu and inevitable impurities, and when viewed from the thickness direction of the foil, the thickness of the second phase is 1 μm or less, and have a lamellar structure interval between the adjacent second phase is 1μm or less, the particle size of the precipitates are the following thickness 20μm is 20 to 100 nm.

The high-strength, high-conductivity heat-resistant copper alloy foil of the present invention is preferably produced by aging treatment at about 400-600 ° C. for 10 hours or more .
The method for producing a high-strength, high-conductivity heat-resistant copper alloy foil of the present invention is a rolled foil of a two-phase alloy composed of a second phase containing 3% to 15% Ag and a Cu parent phase by mass, It contains at least 0.1% and less than 3% of one or more first additive elements selected from the group consisting of Cr, Fe and Fe-P by mass ratio, and the first additive element as a main component The precipitate formed is precipitated at least in the Cu matrix, the balance is made of Cu and inevitable impurities, and when viewed from the thickness direction of the foil, the thickness of the second phase is 1 μm or less, and the adjacent second phase Is a method for producing a high-strength, high-conductivity heat-resistant copper alloy foil having a thickness of 20 μm or less, having a layered structure with an interval of 1 μm or less, and a particle size of the precipitates of 20 to 100 nm, Aged at least 10 hours.

  ADVANTAGE OF THE INVENTION According to this invention, the copper alloy foil excellent in the intensity | strength at the time of making foil, electroconductivity, and heat resistance is obtained.

  Hereinafter, embodiments of a high-strength, high-conductivity heat-resistant copper alloy (hereinafter referred to as “copper alloy” as appropriate) foil according to the present invention will be described. In the present invention, “%” means “% by mass” unless otherwise specified.

<Composition>
The copper alloy foil according to the present invention is a rolled foil of a two-phase alloy composed of a second phase containing 3% or more and 15% or less of Ag by a mass ratio and a Cu parent phase.

[Ag]
When 3% or more of Ag is contained, it is crystallized as an Ag phase (second phase) in the Cu matrix and high strength can be obtained. When the Ag content is less than 3%, the number of Ag crystallized substances is drastically reduced, so that the effect of composite strengthening by the Ag phase is small. On the other hand, if the content exceeds 15%, the heat resistance and hot workability deteriorate, and the effect of increasing the strength is saturated. On the other hand, if the content exceeds 15%, the amount of Ag crystallized at the Cu crystal grain boundary during heat treatment or hot working becomes very large, so that it tends to become a starting point of cracking when the foil is bent.
In addition, content of Ag shows the value in the whole alloy which match | combined Cu mother phase and Ag phase.
In the Ag phase, Ag is crystallized from a molten alloy containing Cu and a predetermined chemical component during casting. The Ag phase contains 50% or more of Ag. The Ag phase is crystallized, for example, in a needle shape in the Cu matrix, but the crystallization form is not limited to this. In addition, although Cu mother phase contains 90% or more of Cu, for example, it is not restricted to this.
The Ag phase can be observed as a composition different from the parent phase by a BSE (backscattered electron) image of an SEM (scanning electron microscope) after polishing the cross section of the rolled structure after the final process. If the structure is difficult to observe, etching or electropolishing may be performed.

[Form of Ag phase]
Double-phase alloys utilize strengthening (elastic effect) based on the composite law of Ag phase, which is stronger than Cu matrix, or strengthening (plastic effect) by increasing the area of the heterophase interface (between Cu matrix and Ag phase). is doing. When the multiphase alloy is strongly processed, the Ag phase as the second phase is finely dispersed in the form of fibers or ribbons, and the area of the heterogeneous interface is increased to strengthen the multiphase alloy. In particular, the effect of increasing the area of the heterogeneous interface is great.

Therefore, 1) the more the second phase is dispersed in the Cu matrix (the more the same volume fraction, the more finely dispersed), 2) the easier the second phase is stretched, and 3) the degree of workability. As the size increases, the strength can be increased. Based on these mechanisms, the present inventors have found that high strength can be obtained by controlling the shape and size of the second phase.
The above 1) can be achieved by optimizing the aging treatment for precipitating Ag and the first additive element. When the aging time is long (at about 400-600 ° C., 10 hours or more, more preferably about 15 hours), not only the first additive element but also Ag precipitates simultaneously. As a result, the characteristics of both the multiphase alloy and the precipitation-type alloy can be obtained by a single heat treatment, and Ag precipitates finely together with the precipitation of additive elements other than Ag.

  As for 2), the first additive element dissolved in the Cu matrix phase is precipitated, whereby the Cu matrix phase is strengthened, and the Ag phase as the second phase is easily stretched. As for the above 3), the greater the degree of processing, the finer the second phase becomes, the area of the heterophase interface increases, and the strength improves. In the present invention, it is necessary to reduce the plate thickness in order to obtain a foil, and the degree of processing increases, so this effect is extremely large. In addition, in order to obtain high strength by controlling the thickness of the Ag phase, it is preferable that the final degree of processing is larger (for example, the degree of processing exceeding 95%).

From the above 1) to 3), when viewed from the thickness direction of the foil, it has a layered structure in which the thickness of the Ag phase is 1 μm or less and the distance between adjacent Ag phases is 1 μm or less. In the present invention, since the degree of processing is increased in order to form a foil, the second phase becomes finer and higher strength can be obtained as compared with conventional alloys.
With such a structure, a high-strength alloy having a 0.2% proof stress of 700 MPa or more is obtained by the fibrous or ribbon-like Ag phase. Furthermore, when the workability is 99.5% or more in this alloy, the thickness of the Ag phase when viewed from the thickness direction of the foil is about 100 nm, and a high strength with a 0.2% proof stress exceeding 1 GPa is obtained.
The Ag phase may be “fibrous” or “ribbon” in terms of obtaining high strength, but if the Ag phase is ribbon, the Ag phase is less likely to be sheared and has heat resistance. While improving, bending workability improves rather than a fibrous phase.

Here, the fibrous form means that the Ag phase is stretched in the rolling direction, but is hardly stretched in the direction perpendicular to the rolling direction (assuming that rolling proceeds in the longitudinal direction of the rolled material). The one that is in the shape. The ribbon shape means that the Ag phase is stretched in the rolling direction and is also stretched in the direction perpendicular to the rolling direction to show a tongue-like shape. When the ribbon-shaped Ag phase is included, bending workability when the material is bent in the direction perpendicular to the rolling direction is improved.
As a form in which the Ag phase is stretched also in the direction perpendicular to the rolling to form a ribbon, for example, when the structure is observed from the direction perpendicular to the rolling, the length of each Ag phase (length in the direction perpendicular to the rolling / The aspect ratio represented by (the length in the thickness direction) is 10 or more.

[First additive element]
In the present invention, the first additive element contains a total of 0.1% or more and less than 3% of one or more first additive elements selected from the group consisting of Cr, Fe, and Fe-P by mass ratio. It is necessary that a precipitate containing as a main component is precipitated at least in the Cu matrix. However, since P alone does not become a precipitate, Fe and P must be used in combination.
When the total content of the first additive elements is less than 0.1%, the effect of precipitation hardening due to precipitation of these elements in the Cu matrix is reduced. On the other hand, if the total content is 3% or more, these precipitate as coarse crystallized products, the workability such as the bendability of the foil deteriorates, and defects such as pinholes occur, and the conductivity is also significantly reduced. To do.
The content of the first additive element in the alloy can be measured using Auger electron spectroscopy. However, since the foil is thin, it is preferable to analyze from the surface direction of the foil.

[Precipitate]
In the present invention, a precipitate mainly composed of the first additive element is precipitated at least in the Cu matrix. Usually, this precipitate precipitates 50% or more in the Cu matrix, and the rest precipitates in the Ag phase. Further, Cr precipitates alone, but Fe and P precipitate as Fe-P intermetallic compounds at a constant composition ratio, and the remaining Fe depositing P and intermetallic compounds precipitates alone.
The particle size of the precipitate is preferably 20 to 100 nm. When the particle size of the precipitate is less than 20 nm, the effect of precipitation hardening of the alloy is reduced, and the precipitate is too fine to be dissolved in the alloy, resulting in a decrease in conductivity. When the particle size of the precipitate exceeds 100 nm, the precipitate becomes coarse, so not only does it become a defect such as a pinhole when it is made into a foil, but also causes a decrease in strength, and cracking occurs when the foil is bent. Easy to start.
[Inclusion]
Preferably, the number of inclusions having a major axis of 1 μm or more present in the copper alloy is 50 pieces / mm ² or less, and more preferably, the number of inclusions is 30 pieces / mm ² or less. The reason for defining the major axis and number of inclusions in this way is that when the thickness of the copper alloy foil becomes 10 μm or less with the fine pitch of the FPC circuit, if the major axis of the inclusion exceeds 1 μm, the copper alloy foil This is because pinholes are likely to occur during manufacturing. Also, when the thickness of the copper alloy foil is 10 μm or less, pinholes become prominent if the inclusions exceed 50 / mm ² in the copper alloy.
Inclusions are coarse particles that are generated under the influence of furnace materials and atmosphere during melting, and generally lead to material defects. The composition of inclusions is mainly oxides, nitrides, silicides, and the like mainly resulting from melting equipment such as furnace materials, but depending on the composition of the alloy to be melted, it may be attributed to additional elements. As an example of the latter, in the case of a Cu—Cr—Zr alloy, inclusions due to Zr are observed because Zr is an active metal.

As a method of controlling the inclusions to the above-mentioned major axis and number, it is possible to control the melting atmosphere or consider the furnace material used during melting. However, when this method is used, it is possible to reduce the influence of the furnace material and atmosphere during melting, but it is difficult to suppress the formation of inclusions due to the alloy composition. Therefore, in the present invention, in order to suppress the formation of inclusions resulting from the alloy composition, the composition and concentration of additive elements (first to third additive elements) in the alloy are defined.
In the present invention, the major axis and the number of inclusions in the alloy can be calculated by the method described below. However, in the image analysis, the inclusions cannot be distinguished from the above precipitates, so all the particles of 1 μm or more are contained. Count as an inclusion. In this case, coarse precipitates are also included in the inclusions. However, since coarse precipitates are particles that cause defects similar to inclusions, there is no problem even if they are counted without distinction, and the smaller the coarse particles, the better.

  The grain size of the precipitates and inclusions is, for example, by cutting the alloy strip before the final cold rolling in parallel with the rolling direction, and viewing the precipitates in the cross section in the thickness direction with a scanning electron microscope or a transmission electron microscope. It can be obtained by observing the degree. When the size of the precipitate is 5 to 50 nm, the magnification is 500,000 to 700,000 times, and when it is 100 to 2000 nm, the image is taken at 5 to 100,000 times. Then, using the image analysis apparatus (for example, Nireco Co., Ltd., trade name Luzex), the major axis a, the minor axis b, and the area are measured for all the individual precipitates having a size of 5 nm or more. The particle size of the precipitates and inclusions can be calculated from the average value thereof.

As a method for controlling the particle size of the precipitate within the above range, adjustment of aging heat treatment conditions can be mentioned. The temperature of the aging heat treatment is preferably 300 to 600 ° C. When the aging treatment temperature is lower than 300 ° C., the particle size of the precipitate may become fine (less than 20 nm) or may not precipitate. On the other hand, when the aging temperature exceeds 600 ° C., the particle size of the precipitate tends to exceed 100 nm.
However, if the degree of work before aging is increased, coarse precipitates are likely to be formed, and if the final degree of work is small, high strength cannot be obtained. In the present invention, it is important that precipitates do not become coarse, and therefore, the degree of processing before aging is preferably about 30-50%. The aging time is preferably about 1 to 100 hours. If the aging time is less than 1 hour, precipitates are difficult to deposit. On the other hand, when the aging time exceeds 100 hours, the dislocations accumulated in the Cu matrix move and tend to recover, leading to a decrease in strength. More preferably, the aging time is about 10 to 100 hours.

[Second additive element]
In this invention, you may contain 0.01% or more and 0.1% or less of the 1st or more 2nd additional element chosen from the group of Mg and Sn further by mass ratio. The second additive element dissolves in the Cu matrix and Ag phase, and strengthens the alloy by solid solution strengthening. However, when Sn is contained, the electrical conductivity of the alloy is lowered, and when Mg is contained, coarse precipitates (Mg oxides) tend to precipitate. Therefore, Sn or Mg may or may not be added depending on the strength required for the alloy foil.
If the content of the second additive element is less than 0.01% in total, the effect of solid solution strengthening is small, and if it exceeds 0.1%, the decrease in conductivity may be significant.
[Third additive element]
In the present invention, the composition further contains one or more third additive elements selected from the group of Gd, Y, Yb, Nd, In, Pd, and Te in a total amount of 0.01% or more and 0.1% or less. May be. The third additive element is dissolved in the Cu matrix and Ag phase to improve heat resistance. When the total content of the third additive element is less than 0.01%, the additive element is not sufficiently dissolved in the Ag phase, and the effect of improving heat resistance is reduced. On the other hand, if the total amount exceeds 0.1%, the conductivity of the alloy tends to be remarkably lowered.
Here, it is preferable that 50 mass% or more of 3rd additive elements are distributed to Ag phase. When the distribution amount of the additive element to the Ag phase is less than 50%, the purity of the Ag phase is high, so the effect of improving the heat resistance is reduced, and the distribution amount of the additive element to the Cu matrix is increased. The conductivity tends to decrease.

In addition, it is thought that most of the first to third additive elements are distributed to the Cu matrix and slightly dissolved in the Ag phase. In order to improve the heat resistance of the multiphase alloy, it is important to prevent the stretched Ag phase from being pinched-off by heat. In the present invention, spheroidization of the stretched Ag phase can be suppressed by uniformly dispersing fine precipitates by the first to third additive elements in the Cu matrix. The uniformly dispersed precipitate has an effect of suppressing dislocation migration (pinning), and is considered to have an interface pinning effect at the interface between the Ag phase and the Cu matrix. In other words, when a certain amount or more of each additive element is added, the additive element precipitates in the form of a simple substance or a compound in the heat treatment during the cold working of the material and in the heat treatment after the cold working. As the temperature rises, the recrystallization temperature also rises.
In addition, part of the first to third additive elements precipitates in the Ag phase, and the Ag phase is strengthened by increasing the recrystallization temperature of the Ag phase. This also improves the heat resistance.

In addition, the ratio by which each additive element is distributed to Ag phase can be calculated | required as follows, for example. First, the cross section of the ingot is mechanically polished, SDS (scanning electron microscope) equipped with EDS (energy dispersive X-ray analysis) or WDS (wavelength dispersive X-ray analysis), or FE-SEM (electrolytic emission scanning electron) Using a microscope), X-ray analysis of the crystallized product and the mother phase is performed. Thereby, the concentration analysis of the additive element contained in each of the Cu matrix and the Ag phase is performed. Here, the concentration of each phase is obtained in advance with reference to the peak value of a standard sample not containing an additive element. In order to perform highly accurate analysis, WDS is preferable to EDS, and it is more preferable to use a field emission electron beam source such as FE-SEM. However, wet analysis is desirable for accurate quantitative analysis.
Actually, the ratio of the additive element concentration in the matrix and the additive element concentration in the Ag phase can be obtained for an ingot in a predetermined field of view.

[Inevitable impurities]
The content of inevitable impurities in the copper alloy need not be as clean as oxygen-free copper C1011 standardized in JIS H2123. For example, you may contain the component of the range normally mixed from a furnace material, a raw material, etc. The copper alloy may contain a total of 0.01% or less of one element selected from the group of Gd, Y, Yb, Nd, In, Pd, and Te as described above. If it is contained, the bendability, conductivity, and strength are hardly impaired. In particular, when Y, Yb, or Nd is contained in the above range in the copper alloy, the heat resistance is increased.

<Method for producing copper alloy foil>
The high-strength, high-conductivity heat-resistant copper alloy foil of the present invention is preferably produced by melt-casting a copper alloy having the above composition and then performing cold working and aging heat treatment after the cold working at least once. it can.
It is preferable that the aging heat treatment condition is within a condition range when adjusting the particle size of the precipitate. When the heat treatment is performed, the additive element dissolved in the Ag phase is precipitated in the Ag phase to further strengthen the Ag phase and further improve the heat resistance. Further, when heat treatment is performed in the above temperature range, the electrical conductivity is recovered to a value of about 50% or more. That is, as the degree of cold working, which will be described later, increases, the decrease in conductivity increases, but the conductivity can be recovered by setting the heat treatment conditions in the above range.
When the heat treatment temperature is less than 300 ° C., precipitation strengthening of the Ag phase by the additive element becomes insufficient, and the conductivity tends not to recover. Further, when the heat treatment temperature exceeds 600 ° C., the electrical conductivity is greatly recovered, but the material tends to soften and the heat resistance tends to decrease.

The total degree of cold working is 90% or more. In the present invention, as already described, when the precipitates of the first additive element and the second phase (Ag phase) are simultaneously deposited by aging heat treatment, the strength is greatly improved even if the degree of work is low. For example, in the case of the present invention, the same degree of strength can be obtained with a workability smaller than the workability (95%) required for manufacturing the alloy described in Patent Document 2, and in this case, industrial merit (reduction of work time) ) Is obtained. Further, since the strength increases as the degree of processing increases, when the degree of processing is equal to that of Patent Document 2 (95%), the Ag phase becomes finer and the strength is further improved.
In the present invention, due to the characteristics of the multiphase alloy, the strength tends to increase as the workability increases. If the total workability is 90% or more, a strength of about 700 MPa or more can be secured. The total workability is the workability from chamfering to the end of cold rolling.

  In addition, this invention is not limited to the said embodiment. Moreover, as long as there exists an effect of this invention, the copper alloy in the said embodiment may contain another component.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these.

1. Manufacture of a sample About each Example and the comparative example, electrolytic copper was melted | dissolved in vacuum and the element of the predetermined composition shown in Table 1, 2 was added, respectively, and the ingot was cast. The ingot was homogenized and annealed (800 ° C, 3 hours), then hot-rolled and further faced. This was cold-rolled at the following total working degree, then subjected to aging heat treatment, and then cold-rolled again to obtain a test piece having a thickness of 0.020 mm (20 μm).
In addition, the total processing degree of each Example was 99.7%, and the aging heat treatment temperature was 450 ° C. × 15 h.

2. Sample Evaluation (1) Ag Phase Thickness and Particle Size of Precipitates and Inclusions For each example and comparative example, the ingot cross section was mechanically polished and crystallized material was observed with an optical microscope, or SEM (scanning) BSE image of the crystallized product was photographed using a scanning electron microscope) or FE-SEM (electrolytic emission scanning electron microscope). This confirmed the two-phase alloy.
Also, the cross section of the ingot is mechanically polished, SDS (scanning electron microscope) equipped with EDS (energy dispersive X-ray analysis), WDS (wavelength dispersive X-ray analysis), or FE-SEM (electrolytic emission scanning). The crystallized product was subjected to elemental analysis using an electron microscope. A point analysis of the crystallized product was performed, or an elemental map of the parent phase and the crystallized product was obtained. This confirmed the Ag phase.
Among the confirmed Ag phases, those having an aspect ratio of 2 or more represented by (length in the direction perpendicular to the rolling / length in the thickness direction of the rolled material) are searched for by measuring the dimensions from the FE-SEM photograph, The thickness (length in the thickness direction) was determined from FE-SEM photographs (10 SEM photographs) and averaged.

Further, a crystallized product having an aspect ratio of less than 2 represented by (length in the direction perpendicular to the rolling / length in the thickness direction of the rolled material) is regarded as the precipitate and inclusions of the present invention, and the average particle size is as follows: It was calculated by the method. First, the alloy strip before the final cold rolling was cut in parallel to the rolling direction, and the precipitates and inclusions in the cross section in the thickness direction were photographed with 10 fields of view with a scanning electron microscope. When the size of the precipitates and inclusions was 5 to 50 nm, the image was taken at a magnification of 500,000 to 700,000 times, and when it was 100 to 2000 nm, the images were taken at 5 to 100,000 times. Then, using the image analysis apparatus (product name: Luzex, manufactured by Nireco Co., Ltd.), the major axis a, the minor axis b, and the area of all the precipitates and inclusions having a size of 5 nm or more are obtained. Measured, and the particle size of the precipitates and inclusions was calculated from the average value.
Note that precipitates mainly composed of Cr, Fe, Fe-P, and the like are less likely to be deformed than the Ag phase and can be regarded as spherical (the aspect ratio is less than 2).
In addition, when the particle size of the precipitate is 1 μm or more, it is impossible to distinguish from oxide-based particles and the like existing in the foil (particle size exceeding 1 μm) by image analysis. Becomes larger.

(2) Measurement of tensile strength According to JIS Z2241, the tensile test was done about the rolling parallel direction of the sample of each Example and the comparative example, and tensile strength (0.2% yield strength (YS)) was measured. The sample was produced according to the above JIS. If the tensile strength (after rolling up) is 700 MPa or more, it can be determined that the tensile strength is excellent.
(3) Measurement of conductivity (EC) The conductivity of the sample was determined by the four-terminal method. If the electrical conductivity is 45% IACS or higher, it can be determined that the electrical conductivity is excellent.
When the first additive element is Cr, the conductivity after rolling tends to be high, which is 60% IACS or more. On the other hand, in the system where the first additive element is Fe-P or Cr and Fe-P is added at the same time, the conductivity after curing is greatly improved, so that the conductivity after rolling is 45% IACS or higher. It is. In the latter case, it may be used as an actual product after curing.
(4) Tensile strength and electrical conductivity after heat treatment In order to simulate the heat treatment of applying and baking a resin on a copper foil when producing CCL, the tensile strength after heat-treating each sample at 320 ° C for 2 hours and The conductivity was measured as described above.

  The obtained results are shown in Tables 1 and 2. In addition, "-" in each table | surface represents not having added the component.

  As is clear from Table 1, in each example, a copper alloy foil having excellent strength and electrical conductivity and a good balance in performance could be obtained. In each of the examples, even after the heat treatment imitating the resin baking process, the decrease in tensile strength was small (YS was 600 MPa or more).

On the other hand, in the case of Comparative Examples 1 and 2 containing no additive element, the tensile strength (anneal softening property) after heat treatment was significantly decreased (20% or more decreased), and the heat resistance was extremely inferior.
In the case of Comparative Example 3 in which the Ag content was less than 3%, a two-phase alloy was not obtained, and the strength was greatly reduced. In Comparative Examples 4 to 5, the total content of the first additive element was 3% or more, and the precipitate (Cr oxide) was coarsened to exceed 100 nm, resulting in a decrease in conductivity.
In the case of Comparative Example 6 in which only P was added as the first additive element, no precipitate was deposited and the conductivity was lowered. This is presumably because P was dissolved in the alloy.

In Comparative Examples 7 and 8, coarse Fe-P precipitates were formed. This precipitate affects bending workability. In addition, since the compound of Fe and P becomes coarse as the addition of P increases, in each Example, as a result of defining the addition amount of P to 0.01-0.1 wt%, no coarse precipitate was generated.
In the case of Comparative Examples 9 and 10 in which the total content of the first additive element is less than 0.1%, the strength difference between the rolled up material and the material after heat treatment at 320 ° C. becomes large, and the actual use stability is increased. Not suitable in terms of (anneal softening characteristics).
In the case of Comparative Example 11 in which the content of Mg as the second additive element exceeded 0.1%, the conductivity decreased and a coarse Mg oxide exceeding 100 nm precipitated. If there are coarse precipitates, there is a concern about defects such as pinholes.
In the case of Comparative Example 12 in which the content of Sn as the second additive element exceeded 0.1%, the electrical conductivity decreased.
In the case of Comparative Example 13 in which the total content of Mg and Sn as the second additive elements exceeded 0.1%, coarse Mg oxide was precipitated and the conductivity was further lowered.

In Comparative Examples 14, 15, and 17 in which the thickness of the second phase exceeded 1 μm and the interval between adjacent second phases also exceeded 1 μm, the strength was greatly reduced.
In the case of Comparative Example 16 in which the interval between adjacent second phases was less than 1 μm but the thickness of the second phase exceeded 1 μm, the strength was significantly reduced as compared with Example 15 having the same Ag concentration. did.

Claims (3)

A rolled foil of a two-phase alloy composed of a second phase containing 3% to 15% Ag by mass and a Cu matrix, and one kind selected from the group of Cr, Fe and Fe-P by mass Alternatively, a precipitate containing at least 0.1% and less than 3% of the first additive element of two or more kinds and having the first additive element as a main component is precipitated at least in the Cu matrix, and the balance is Cu and inevitable manner consists impurities, when viewed from the thickness direction of the foil, the second phase is the thickness of the 1μm or less, and the spacing between adjacent second phases have a lamellar structure is 1μm or less, the precipitates A high-strength, high-conductivity heat-resistant copper alloy foil having a particle size of 20 to 100 nm and a thickness of 20 μm or less. The high-strength, high-conductivity heat-resistant copper alloy foil according to claim 1, which is produced by aging treatment at about 400-600 ° C for 10 hours or more . A rolled foil of a two-phase alloy composed of a second phase containing 3% to 15% Ag by mass and a Cu matrix, and one kind selected from the group of Cr, Fe and Fe-P by mass Alternatively, a precipitate containing at least 0.1% and less than 3% of the first additive element of two or more kinds and having the first additive element as a main component is precipitated at least in the Cu matrix, and the balance is Cu and inevitable Having a layered structure in which the thickness of the second phase is 1 μm or less and the interval between adjacent second phases is 1 μm or less when viewed from the thickness direction of the foil, A method for producing a high-strength, high-conductive, heat-resistant copper alloy foil having a particle size of 20 to 100 nm and a thickness of 20 μm or less,
  A method for producing a high-strength, high-conductivity heat-resistant copper alloy foil that is aged at 400-600 ° C for 10 hours or longer.