TWI681933B - Copper alloy for electrical and electronic parts and semiconductors with high strength and high electrical conductivity and method of preparing the same - Google Patents

Abstract

Disclosed are a copper alloy for electrical and electronic parts and semiconductors having high strength and high electrical conductivity and a method of preparing the same. The copper alloy includes 0.09 to 0.20 % by mass of iron (Fe), 0.05 to 0.09 % by mass of phosphorous (P), 0.05 to 0.20 % by mass of manganese (Mn), the remaining amount of copper (Cu) and 0.05 % by mass or less of inevitable impurities, and has tensile strength of 470 MPa or more, hardness of 145 Hv or more, electrical conductivity of 75%IACS or more and a softening resistant temperature of 400℃ or higher.

Description

Copper for electrical and electronic components and semiconductors with high strength and high conductivity Alloy and its preparation method

The present invention relates to a copper alloy used for electrical and electronic parts and semiconductors with high strength and high conductivity, and a preparation method thereof; more specifically, to a copper alloy including copper (Cu), iron (Fe), and phosphorus ( P) Copper alloy with manganese (Mn) and its preparation method.

Since copper alloys are used for various purposes, that is, as materials for semiconductor lead frames, electrical and electronic components, etc., Cu-Fe-P groups containing iron (Fe) and phosphorus (P) are generally used alloy. For example, in a copper alloy, a copper alloy C19210 containing Fe in a mass ratio of 0.05 to 0.15% and P in a mass ratio of 0.025 to 0.04%, or Fe containing a mass ratio of 2.1 to 2.6% in a mass ratio of The copper alloy C19400 of 0.015 to 0.15% P and zinc (Zn) with a mass ratio of 0.05 to 0.2% has excellent strength and conductivity, so it is widely used as a material for lead frames. The reason why Fe and P are the main added elements is that they form a precipitated phase in the copper matrix to produce excellent strength and conductivity.

However, among the various characteristics of copper alloys, strength and conductivity are in conflict with each other, that is, inversely proportional to each other, and therefore, when the strength increases, the conductivity will inevitably decrease, and when the conductivity increases, the strength That is inevitably reduced. Therefore, the traditional copper alloy C19210 with a tensile strength of 400 MPa and a conductivity of 80% IACS has poor strength but excellent electrical conductivity, so it is used in products requiring high conductivity; and has a resistance of 500 MPa The traditional copper alloy C19400 with tensile strength and 60% IACS conductivity has excellent strength, and is therefore used in products requiring high strength.

Recently, based on the trend of thinning and miniaturization of electrical and electronic components, the characteristics of materials have become more important. Since semiconductor devices used in electronic equipment, vehicles, etc. are trending toward large capacity, miniaturization, and high integration, the lead frames used in semiconductor devices are now miniaturized and thin. Therefore, compared to traditional copper alloys, copper alloys provide high strength, high electrical conductivity, and excellent processing ability. Moreover, based on the reduction in thickness of electronic products, it is necessary to meet the tensile strength of 470MPa or higher and 75% at the same time. IACS or higher conductivity copper alloy. Therefore, in order to meet these requirements in the industry, efforts are needed to improve both the strength and the electrical conductivity that conflict with each other.

In order to increase the strength of the copper alloy, it is necessary to increase the Fe and P content, or add a third element (such as tin (Sn), magnesium (Mg) or nickel (Ni)); but when the content of these elements increases, the copper alloy The strength will increase, but the conductivity of the copper alloy will decrease. Therefore, in addition to adding elements, it is replaced by grain refinement or control of the size and distribution of crystallized and precipitated substances to improve the characteristics of the copper alloy. However, various problems occur in this case, such as surface defects, reduced reliability, uneven microstructure, and the like. Therefore, the improvement of both strength and conductivity of copper alloys is a difficult and important research topic.

In addition, in the field of applying copper alloys, a heating process is performed. Therefore, the copper alloy needs to have heat resistance and this characteristic is called softening resistance (which is evaluated based on the softening temperature resistance). The softening resistance indicates that the hardness value of the prepared copper alloy sheet after 1 minute heat treatment corresponds to the initial 80% of the initial hardness value (before heat treatment). The softening resistance temperature is used as an indicator to indicate whether the corresponding material is heat-resistant, which is related to the reliability of the final product, as described above. In traditional semiconductor packaging structures or electronic components, copper alloys with a softening resistance of about 380°C will not cause problems in the manufacture of the product and the reliability of the final product. However, recently copper alloys used in semiconductor packages and electronic components require better softening resistance due to the addition of heating processes (such as soldering or wire bonding) to product processing, so the softening resistance needs to be increased to 400 ℃ or higher resistance to softening temperature.

Many patents have been applied for obtaining the strength and conductivity required for the copper alloy material of the lead frame.

Korean Patent Publication No. 10-2008-0019274 discloses that the strength of Cu-Fe-P-based alloys is improved by adding magnesium (Mg). However, when Mg is added to the alloy, the conductivity of the alloy is inevitably reduced. When Mg is added to the traditional Cu-Fe-P-based alloy, the alloy will exhibit a tensile strength of 450 MPa and a conductivity of 70% IACS, which is lower than the characteristics currently required for lead frames (tensile strength of 470 MPa or higher) Strength, and conductivity of 77% IACS or higher), and the reason is due to the coarse Mg-P-based crystalline material. When Mg is added to the alloy, the strength and conductivity of the alloy will inevitably decrease due to the coarse Mg-P-based crystalline material, inevitably from the beginning of casting to the end of hot rolling and defects.

In addition, Korean Patent Publication No. 10-2005-0076767 discloses that the strength of Cu-Fe-P-based alloys is strengthened by controlling the particle size of precipitates in the alloy. However, in this patent document, in order to finely control the particle size of the precipitates, two or more cold rolling and annealing procedures need to be performed, and therefore various variables occur and it is difficult to actually prepare this alloy on an industrial scale. In addition, this patent document describes that the volume ratio of the precipitate is 1% or more, and the number of particles of the precipitate is 300/μm ² or more, but the volume ratio is a value including the number of coarse particles.

In addition, Korean Patent Publication No. 10-2013-0136183 discloses that the strength of Cu-Fe-P-based alloys is enhanced by adding manganese (Mn) to the alloy, but the prepared alloy does not meet the actual strength required by industrial sites And conductivity. In addition, claim 4 of this patent document describes that the particle size of precipitates is 10-30 μm, but in essence, the particle size of 10-30 μm is too large, and these particles correspond to casting defects or foreign substances rather than precipitates , So the strength and conductivity are not improved. In this respect, if there are particles of 10-30 μm in the copper alloy, the characteristics of the copper alloy will be deteriorated, and it will be difficult to perform the semiconductor packaging process due to poor surface quality. In addition, the above-mentioned patent documents do not specify any analysis results or the basis for determining the type of precipitates. In the SEM analysis results shown in the third figure, only grain boundaries are observed instead of precipitates, and no technical basis is provided.

One of the objects of the present invention is to provide a copper alloy for electrical and electronic components and semiconductors, which has strength and conductivity that satisfy the characteristics currently required in the industry that conventional technology cannot meet, and has excellent resistance Softening; and its preparation method.

In order to achieve these objectives and other advantages, and according to the idea of the present invention, as embodied and widely described herein, a copper alloy for electrical and electronic components and semiconductors includes iron (Fe), mass of 0.09 to 0.20% by mass, mass Phosphorus (P) with a ratio of 0.05 to 0.09%, manganese (Mn) with a mass ratio of 0.05 to 0.20%, copper (Cu) with a residual content, and inevitable impurities with a mass ratio of 0.05% or less, of which Impurities to avoid include from silicon (Si), zinc (Zn), calcium (Ca), aluminum (Al), titanium (Ti), beryllium (Be), chromium (Cr), cobalt (Co), silver (Ag) In the group formed with zirconium (Zr) At least one selected; and the copper alloy has a tensile strength of 470 MPa or higher, a hardness of 145 Hv or higher, a conductivity of 75% IACS or higher, and a softening resistance temperature of 400° C. or higher. The impurities have a content of 0.01% or less by mass. The copper alloy for electrical and electronic components and semiconductors may further include at least one of nickel (Ni) or tin (Sn) in a mass ratio of 0.0001 to 0.03%.

The copper alloy has an average grain size of 20 μm or less and a standard deviation of 5 μm or less, resulting from the grain size measured using a field emission scanning electron microscope (FE-SEM).

The copper alloy includes (FeMn) ₂ P precipitates. The (FeMn) ₂ P precipitate is observed by using a high-resolution transmission electron microscope (HR-TEM) or a field emission transmission electron microscope (FE-TEM) at a magnification of 100,000x or more A sample prepared by the extraction and replication method is measured, and has an average particle size of 50 nm or less and an area density of 1.0*10 ¹⁰ /cm ² or more.

The copper alloy can be made as a sheet or plate.

In another concept of the present invention, a method for preparing a copper alloy for electrical and electronic components and semiconductors includes: melting the component elements as described above to cast an ingot, homogenizing the heat treatment at a temperature of 900 to 1000°C The obtained ingot is up to 1 to 4 hours, and then hot rolled at a processing rate of 85 to 95%, cold rolled the product obtained in the previous step at a processing rate of 87 to 98%, at a temperature of 430 to 520°C The product obtained in the previous step is subjected to precipitation heat treatment for 1 to 10 hours, and the product obtained in the previous step is rolled at a reduction ratio of 10 to 90% to produce a final product.

The copper alloy according to the present invention has excellent strength and electrical conductivity, and has excellent softening resistance. In addition, when the copper alloy is prepared through the preparation process according to the present invention, although the process cost is reduced, the obtained copper alloy will exhibit excellent strength and conductivity, and apart from the separated transistor and semiconductor lead frame, It can also be applied to various electrical and electronic components.

The first figure is a graph illustrating the softening resistance characteristics of the copper alloy prepared according to Example 5 and the conventional copper alloy.

The second image A is an FE-SEM photograph showing the microstructure after hot rolling at 870°C in the process for preparing the copper alloy having the composition as described in Example 1.

The second image B is a FE-SEM photograph showing the microstructure after hot rolling at 900°C in the process for preparing the copper alloy having the composition as described in Example 1.

The second image C is a FE-SEM photograph showing the microstructure after hot rolling at 950°C in the process for preparing the copper alloy having the composition as described in Example 1.

The third figure is a FE-FEM photograph showing the microstructure of the copper alloy prepared according to Example 5.

The fourth image A is an FE-TEM photograph of a sample prepared by the ion milling method to confirm the precipitates in the copper alloy having the composition of Example 5.

The fourth image B is an FE-TEM photograph of a sample prepared by the carbon extraction and replication method to confirm the precipitates in the copper alloy having the composition of Example 5.

The invention provides a copper alloy with high strength and electrical conductivity and excellent softening resistance, used in electrical and electronic parts and semiconductors, and a preparation method thereof. In the following description, "%" refers to the mass ratio (% by mass) indicating the content of the constituent elements, unless otherwise stated.

Copper alloy according to the invention

The copper alloy according to the present invention includes iron (Fe) in a mass ratio of 0.09 to 0.20%, phosphorus (P) in a mass ratio of 0.05 to 0.09%, manganese (Mn) in a mass ratio of 0.05 to 0.20%, and a residual content of copper (Cu) and inevitable impurities with a mass ratio of 0.05% or less, the inevitable impurities include from silicon (Si), zinc (Zn), calcium (Ca), aluminum (Al), titanium (Ti ), beryllium (Be), chromium (Cr), cobalt (Co), silver (Ag) and zirconium (Zr) selected from the group consisting of at least one; and the copper alloy is a kind of electrical and electronic A copper alloy for parts or semiconductors, which has a tensile strength of 470 MPa or higher, a hardness of 145 Hv or higher, a conductivity of 75% IACS or higher, and a softening resistance temperature of 400° C. or higher.

Hereinafter, the composition of the copper alloy according to the present invention will be described. In the following description, unless otherwise stated, the% representing the element content refers to the mass ratio (% by mass).

[Iron (Fe)]

Fe is an element necessary to form fine (FeMn) ₂ P precipitates to improve strength or conductivity, and the Fe content is in the range of 0.09 to 0.20%. If the Fe content is less than 0.09%, the particles required to form precipitates are insufficient, and the effect of suppressing the growth of crystal grains due to the precipitates is reduced. Therefore, the average crystal grain size or the standard deviation of the average crystal grains will increase excessively, thus decreasing the strength. Therefore, in order to effectively exhibit the effect, the Fe content needs to be 0.09% or higher. However, when the Fe content exceeds 0.20% (that is, excessive increase), it causes coarsening of the precipitates, and the standard deviation of the average crystal grains increases excessively, thereby reducing bending workability and electrical conductivity.

[Phosphorus (P)]

In addition to deacidification, P combines with Fe and Mn, and thus forms fine (FeMn) ₂ P precipitates to improve the strength or conductivity of the copper alloy. The P content is 0.05 to 0.09%. When the P content is less than 0.05%, the formation of fine precipitates is insufficient, and the effect of suppressing grain growth due to the precipitates is reduced. Therefore, the average crystal grain size or the standard deviation of the average crystal grains will increase excessively, thus decreasing the strength. Therefore, the P content needs to be 0.05% or higher. However, if the P content exceeds 0.09% (that is, excessive increase), coarse precipitate particles increase, the standard deviation of the average crystal grains increases, and the bending workability decreases accordingly. In addition, the conductivity will also be reduced.

[Manganese (Mn)]

According to reports, the Mn added to the copper alloy generally helps to increase the strength of the copper alloy. If only adding Mn to the copper alloy to increase the strength, the conductivity of the finally obtained copper alloy product will inevitably decrease. (FeMn) ₂ P precipitates are formed in the copper alloy according to the present invention, and therefore both the strength and conductivity of the copper alloy can be improved. In the copper alloy according to the present invention, the Mn content is 0.05 to 0.20%. If the Mn content is less than 0.05%, the formation of precipitates will be insufficient, and the effect of suppressing the growth of crystal grains due to precipitates will be reduced, so the strength will be reduced, as in the case of Fe. However, when the Mn content exceeds 0.20%, both strength and conductivity will be reduced due to coarse crystalline substances or casting defects.

[Unavoidable impurities]

In addition, the copper alloy according to the present invention contains 0.05% or less of at least one selected from the group consisting of Si, Zn, Ca, Al, Ti, Be, Cr, Co, Ag, and Zr. Preferably, the impurity content is 0.01% or lower. These elements are elements to improve various characteristics of the copper alloy, and can be added selectively according to the application.

In the copper alloy according to the present invention, if Mg, which is widely known to have an excellent strengthening effect, is added to the copper alloy, the strength of the finally obtained copper alloy product will be improved, but the conductivity of the product inevitably decreases And, Mg reacts with P and produces coarse Mg-P-based crystalline substances and defects from the beginning of casting to the end of hot rolling. Therefore, Mg should be excluded.

[Nickel (Ni)] and [tin (Sn)]

The copper alloy according to the present invention may further contain 0.0001% to 0.03% of at least one of Ni or Sn. Ni is dissolved in the Cu matrix, so it has the effect of improving strength, and can effectively provide heat resistance. If the Ni content is less than 0.0001%, the strength of the copper alloy cannot be improved; moreover, if the Ni content exceeds 0.03%, the conductivity of the copper alloy will be reduced.

Sn is a solid solution strengthening alloy element, which is dissolved in the Cu matrix to increase strength. If the Sn content is less than 0.0001%, it is difficult to predict the strength improvement of the copper alloy; and, if the Sn content exceeds 0.03%, the conductivity of the copper alloy will be reduced.

[Characteristics of the copper alloy according to the present invention]

In general, in copper alloys, as the strength of the copper alloy increases, the conductivity of the copper alloy decreases, making it difficult to control both characteristics.

The strength of the copper alloy according to the present invention can satisfy both the tensile strength of 470 MPa or higher and the hardness of 145 Hv or higher. These are the values that reflect the recent needs of the industry, and are considered to be limiting values when considering the strength and conductivity of copper alloys that have an inverse relationship.

In addition, copper alloys used in semiconductors or electrical and electronic components should have a conductivity of 75% IACS or higher. If the conductivity of the copper alloy is less than 75% IACS, the transmission of electrical signals is not effective, so the copper alloy cannot be used in products. The electrical conductivity of the copper alloy according to the present invention is 75% IACS or higher.

That is, the copper alloy according to the present invention has excellent characteristics, that is, both enhanced strength and electrical conductivity.

The copper alloy according to the present invention has an excellent softening resistance temperature of 400°C or higher. In the following, a detailed description of the softening temperature resistance will be provided in the preparation method of the copper alloy according to the present invention.

[The preparation method of the copper alloy according to the present invention]

The copper alloy according to the present invention can be prepared by the following method. First, the component elements according to the above composition are melted to cast an ingot. The obtained ingot is subjected to homogenization heat treatment at a temperature of 900 to 1000°C for 1 to 4 hours, and then immediately hot-rolled at a processing rate of 85 to 95%. While hot rolling is completed, the resulting product is water-quenched for solution treatment of solute elements, and then cold-rolled at a processing rate of 87 to 98%. After accumulating high strain energy through such cold rolling and thus increasing the driving force for generating precipitates, the resulting product is subjected to precipitation heat treatment at 430 to 520°C for 1 to 10 hours. Next, the resulting product is rolled with a reduction ratio of 10 to 90%, thus determining the final thickness of the final product.

The individual operations of the method for preparing a copper alloy according to the present invention will be explained in more detail below.

First, the above constituent elements are melted to cast an ingot.

Then, after the resulting product was subjected to a homogenization heat treatment at a temperature of 900 to 1000° C. for 1 to 4 hours, it was immediately hot-rolled at a processing rate of 85 to 95%. Homogenization heat treatment is a basic pre-treatment for hot rolling, so that the ingot is hot rolled in a fully heated state instead of in a cold working state to remove the cast structure and produce a new recrystallized structure. In the method of preparing a copper alloy according to the present invention, hot rolling is the most important operation. Hot rolling conditions are factors that have an important influence on the metal structure that produces alloy characteristics. Different structures are formed after hot rolling according to the hot rolling conditions, so that the characteristics of the final product will change. The hot rolling conditions include hot rolling temperature, the number of passes during hot rolling, cooling conditions, etc., and the structure obtained after hot rolling will vary according to various conditions.

To achieve the characteristics of the copper alloy according to the present invention, the hot rolling temperature should be in the range of 900 to 1000°C. When the hot rolling temperature falls within this range, an anisotropic recrystallized structure with non-directionality can be obtained. As confirmed in the following example, if the hot rolling temperature is lower than 900°C, the processed structure (rolled structure) is still Is retained. In the traditional copper alloy used for general lead frames, in order to avoid the deterioration of the characteristics of the final product, one or more solution treatment and precipitation processes should be added, which will lead to an increase in cost and a reduction in yield. On the other hand, the copper alloy according to the present invention has its characteristics without any additional process, and therefore can reduce the processing cost and increase the production volume.

When the ingot is heated to a temperature of 900 to 1000°C for 1 to 4 hours for homogenization heat treatment, an anisotropic recrystallization structure can be obtained at the same time, showing the effect of solution treatment. When the ingot is heated for less than 1 hour, the processing structure is still partially retained, and the ingot cannot fully exhibit the characteristics of anisotropic recrystallization structure; while when the ingot is heated for more than 4 hours, the ingot Will partially melt. Solution treatment is a procedure to dissolve the amount of elements exceeding the dissolution capacity in the Cu matrix under supersaturated state, and therefore the precipitation effect can be maximized. In general precipitation-strengthened alloys, it is necessary to perform an independent additional solution treatment process on the alloy with a thin film thickness, so the treatment cost will increase and the output will decrease. However, in the copper alloy according to the present invention, the solution treatment effect is obtained through the heat treatment in the hot rolling process, so the high strain energy will pass through the strong rolling in the subsequent cold rolling process with a processing rate of 87 to 98% System and accumulate in the material. The high strain energy in the material serves as the driving force for the precipitation process after cold rolling, so fine precipitates can be evenly distributed in the precipitation process.

Then, at the same time when the hot rolling is completed, the product obtained from the previous step is quenched with water to perform the solution treatment of the solute element, and then it is cold rolled at a processing rate of 87 to 98%. High strain energy accumulates through this cold rolling, so the driving force for generating precipitates can be increased.

Then, the product obtained from the previous step is subjected to precipitation heat treatment at a temperature of 430 to 520°C for 1 to 10 hours. The copper alloy according to the present invention is a precipitation strengthening alloy, so the precipitation process is important. In addition, the copper alloy according to the present invention is designed to additionally contain Mn, but the optimum strength and conductivity of the copper alloy cannot be obtained by adding Mn alone. These properties are obtained by uniformly distributing fine precipitates during the precipitation process. In the traditional Cu-Fe-P-based alloy, the Fe ₂ P precipitates are mainly present in the copper alloy, but the coarse FeP precipitates are locally present, so that the characteristics of the copper alloy are deteriorated. On the other hand, in the copper alloy preparation method according to the present invention, the precipitation heat treatment is performed under the above conditions, and therefore, the fine (FeMn) ₂ P precipitate system is distributed in the copper alloy, and therefore high strength and high Conductivity both.

Finally, the product obtained in the previous step is rolled at a reduction rate of 10 to 90%. Here, the product is cold-rolled at a processing rate of 10 to 90%, thereby obtaining the target physical properties. Here, the preferable range of the processing rate is 30 to 70%. Within this range, the strength increase efficiency of the processing amount of the copper alloy according to the present invention can be maximized.

In addition, in the above method, after precipitation heat treatment and before final rolling of the final product, cold rolling with a processing rate of 30 to 90% may be performed as necessary, and then intermediate heat treatment is performed. This kind of cold rolling and intermediate heat treatment at a processing rate of 30 to 90% is not necessary, but can be performed to solve the problem of surface quality, such as sintering (burning) due to the processing or preparation conditions of the precipitation heat treatment equipment of the main production line (Partial adhesion due to heat and pressure), scratches caused by the surface pickling process after precipitation heat treatment, etc. If there is a large difference between the thickness of the product after precipitation heat treatment and the thickness of the final product after final rolling, and the final product exceeds the target physical properties (strength and conductivity), then intermediate heat treatment can be carried out, otherwise it will be difficult to obtain Target characteristics. Here, since the main purpose of the intermediate heat treatment is to reduce the strength of the copper alloy, but the conductivity reduction of the copper alloy must be minimized, the intermediate heat treatment is important to reduce the conductivity in the range of 0.1 to 3% IACS. If the value of the reduced conductivity is less than 0.1% IACS, the heat treatment has no effect; and if the value of the reduced conductivity exceeds 3% IACS, the heat treatment has a good effect, but there is a copper alloy that deviates from the target due to its reduced conductivity and strength Possibility of characteristics.

In the preparation method of the copper alloy according to the present invention, hot rolling and precipitation heat treatment processes have an important influence on the characteristics of the finally obtained copper alloy, and, in order to distribute fine (FeMn) ₂ P precipitation in the copper alloy according to the present invention The hot rolling process to the precipitation process all need to be controlled accurately and sequentially. In order to confirm the fine precipitates generated in the copper alloy, observation using FE-SEM and FE-TEM is necessary.

The copper alloy prepared according to the method of the present invention contains fine (FeMn) ₂ P precipitates, and, when the microstructure is observed at a magnification of 100,000x or higher using FE-TEM crystal orientation analysis, (FeMn) The average particle size of ₂ P precipitates is 50 nm or less, and the area density of (FeMn) ₂ P precipitates is 1.0*10 ¹⁰ /cm ² or more.

In order to observe the precipitates, TEM samples are traditionally prepared by the general ion milling method. However, it is difficult to observe fine precipitates with a particle size of several nanometers or tens of nanometers using this sample. Even if an attempt is made to observe fine precipitates, it is difficult to distinguish the precipitates from impurities or foreign substances in the TEM sample prepared by the ion milling method, and the crystal structure and composition of the precipitates cannot be confirmed. On the other hand, by TEM analysis of the sample prepared by the carbon extraction repeat method, fine precipitates in the copper alloy according to the present invention can be observed.

In the copper alloy according to the present invention, fine (FeMn) ₂ P precipitates are uniformly distributed within the grain boundaries and inside the crystal grains, and the average particle size of the (FeMn) ₂ P precipitates is 50 nm or less. If the average particle size of the precipitate exceeds 50 nm, the conductivity will inevitably decrease, and this will lead to poor reliability in the semiconductor manufacturing process. The average particle size of the precipitate can be measured by field emission transmission electron microscopy (FE-TEM) crystal orientation analysis and observation at a magnification of 100,000x or higher. In this regard, the fourth graph A and the fourth graph B illustrate the results of FE-TEM analysis of the copper alloy according to the present invention in the following examples.

In addition, the area density can be measured based on the FE-TEM results shown in the fourth A and fourth B diagrams. Area density refers to the number of precipitates present in a specified area and is used as an index to estimate the distribution of precipitates. Traditionally, the volume ratio is used to estimate the distribution of precipitates, but the volume ratio represents the percentage of precipitates in a specified area. Therefore, if coarse particles with large sizes are generated, the error range becomes considerable. On the other hand, if the concept of area density is used, the presence of coarse particles does not affect the area density, and the degree of distribution of precipitates can be confirmed more accurately. The area density of the copper alloy according to the present invention is 1.0*10 ¹⁰ /cm ² or higher. Since the average particle size of (FeMn) ₂ P precipitates of the copper alloy according to the present invention is very fine, that is, 50 nm or less, in order to exhibit the characteristics of the copper alloy according to the present invention, a large amount of precipitates is required, Therefore, if the number of precipitates (that is, area density) is less than 1.0*10 ¹⁰ /cm ² , the copper alloy cannot have sufficient strength.

The softening temperature of the copper alloy according to the present invention is 400°C or higher. In order to have sufficient softening resistance in electrical and electronic parts and semiconductors, the softening temperature of copper alloys must be 400°C or higher. In the present invention, precipitation strengthening (rather than grain refinement) is performed as a way to increase the strength of the copper alloy, so the copper alloy has excellent softening resistance. If severe plastic deformation is performed to achieve grain refinement, defects will soften due to high internal stress. Defect softening means that the hardness of the material decreases due to heat during material processing and packaging of the semiconductor device, thus producing defective products.

Copper alloys for electrical and electronic components and semiconductors according to the present invention can be prepared as sheets or plates. This type of sheet or plate type copper alloy is suitable for use in semiconductor or IC lead frames or connectors, and terminals.

Compared with traditional products, the copper alloy according to the present invention has excellent strength and conductivity, and has excellent resistance to softening by mixing the composition of the copper alloy and precisely controlling the preparation process, as described above, so not only Particularly suitable for electrical and electronic components (e.g. traditionally used semiconductor leads Frames, terminals, connectors, switches, relays, etc.) are also suitable for discrete transistors (that is, automotive power control semiconductors) that have recently increased in demand.

Examples

Example 1 to Example 16

The samples of Examples 1 to 16 were prepared according to the compositions disclosed in Table 1 below. In the following, a method of preparing a sample will be explained.

The alloy elements containing copper are mixed according to each composition disclosed in Table 1 per 1 kg, and the resulting mixture is melted in a high-frequency melting heating furnace, and then made into a thickness of 20 mm, a width of 50 mm, and a length of 160 to 180 mm. Ingot. In order to remove bad parts, such as fast cooling parts and shrinkage cavities, the bottom and top of the prepared ingots will be cut off by a length of 20 mm, and then the ingots will be processed in a box-type heating furnace at 900°C Homogenization heat treatment for 2 hours. Immediately after the homogenization heat treatment, hot rolling with a processing rate of 90% is performed. After the hot rolling is completed, the solution treatment is performed by water quenching to suppress the precipitation of solute elements. Before the precipitation process, cold rolling is performed at a processing rate of 90%, so that high strain energy is accumulated through this cold rolling, thus increasing the driving force for generating precipitates. Thereafter, precipitation heat treatment was performed at a temperature of 450° C. for 3 hours, and then cold rolling was performed at a processing rate of 50%. Finally, the final product of the copper alloy was prepared as a sample, the sample size was 0.3t*30w*200l, and the sample was used in subsequent tests. Table 2 shows the characteristic analysis results of the copper alloy samples prepared in Examples 1 to 16, which are disclosed in the Test Example.

Comparative Example 1 to Comparative Example 16

The samples of Comparative Examples 1 to 16 were prepared according to the composition disclosed in Table 1 under the same conditions as in Examples 1 to 16 by the preparation method. Table 2 also presents the characteristics analysis results of the copper alloy samples prepared in Comparative Examples 1 to 16.

Examples 1 to 14 are examples of evaluating the critical significance of the composition range of Cu, Fe, Mn, and P shown in Table 1. Examples 14 to 16 are examples confirming the effect of adding elements such as Ni and Sn. Comparative Example 1 has the same composition as alloy C19210, which is widely used in lead frames. In addition, the compositions of Comparative Examples 8 to 13 include Mn in addition to the composition of alloy C19210.

[Test example]

In the following, a characteristic analysis method of copper alloy samples prepared according to Examples and Comparative Examples will be explained.

Tensile strength is measured using ZWICK ROELL Co., Ltd.'s universal testing machine Z100; hardness is measured using INSTRON Co., Ltd.'s Vickers hardness tester TUKON 2500 with a load of 1 kg: conductivity is measured using SIGMATEST from FOERSTER Co., Ltd.

In the analysis of softening temperature resistance, Thermolyne 5.8L D1 Benchtop Muffle Furnace heating furnace of THERMO SCIENTIFIC Co., Ltd. was used for heat treatment. In more detail, after performing sample heat treatment at 300, 350, 400, 450, 500, 550, 600, 650, and 700°C for 1 minute, measure the hardness value of the sample and draw a dotted line graph (where the Y axis represents (Hardness, X axis represents temperature), and the temperature value that intersects the point corresponding to 80% of the initial hardness is calculated as the softening resistance temperature. The results are shown in the first graph, in which the copper alloy system of Example 5 is exemplarily compared with the conventional copper alloys C19400 and C19210.

The average crystal grain size of the microstructure of the sample was measured using Quanta650FEG (FE-SEM) of FEI Co., Ltd. In order to measure the average crystal grain size, after performing electrolyte polishing on the surface of the sample, the sample is inserted into the FE-SEM furnace body, the pressure inside the chamber is maintained at 1*10 ^-5 Torr or lower, and then irradiated with an ion beam Observe the sample through crystal orientation analysis. The third graph illustrates the observation results of the microstructure of the copper alloy of Example 5.

The average particle size and area density of the precipitates were measured using JEM-2100F (FE-TEM) of JEOL Co., Ltd. In order to observe the sample using FE-TEM, the analysis was carried out by two methods, and the fourth graph A shows the FE-TEM result using the general sample preparation method (ie, ion milling method). As illustrated in the fourth graph A, it is difficult to confirm and analyze fine precipitates. Therefore, in order to analyze fine precipitates that cannot be confirmed by the ion milling method, Figure 4B shows the results of FE-TEM analysis of samples prepared by the carbon extraction repeat method.

Table 2 below shows the measurement results according to the above characteristic analysis method.

In Table 2 above, through comparison between Example 4 and Example 8, it can be confirmed that the copper alloy of Example 4 (which has a P increment in addition to the copper alloy composition of Example 8) provides a sufficient amount of P to form fine (FeMn ) ₂ P precipitates and therefore has both enhanced strength and conductivity. In addition, from the results of Example 5, it was confirmed that the copper alloy of Example 5 has both excellent strength and electrical conductivity.

On the other hand, the copper alloys of Comparative Examples 1 to 16 do not satisfy the strength corresponding to one of the characteristics required in the industry, even if the precipitation control is implemented by optimizing the preparation process. The reason for this is that the copper alloy deviates from the optimal composition of the copper alloy according to the present invention, and therefore it is difficult to form fine (FeMn) ₂ P precipitates.

Among the above-mentioned comparative examples, comparative examples 8 to 13 are comparative examples for confirming whether merely adding Mn to the conventional alloy C19210 is effective. From the results of Comparative Examples 8 to 13, it can be confirmed that with simple addition of Mn, any composition cannot satisfy the required characteristics. The reason is that (FeMn) ₂ P precipitates cannot be formed by simple addition of Mn, and Mn is dissolved in the Cu matrix, thus reducing the conductivity; and this problem is due to the lack of formation of (FeMn) ₂ P precipitates Due to P content. In particular, it can be confirmed that the simple solid solution strengthening of the additive element increases the strength to some extent, but the electrical conductivity is greatly reduced.

Summarizing the above characteristic analysis results, it can be confirmed that the composition of the conventional copper alloy C19210 still cannot exhibit improved alloy characteristics even when combined with the same preparation methods and analysis methods as Examples 1 to 16 having the characteristics of the copper alloy according to the present invention.

In order to evaluate the characteristics of the copper alloy according to the hot rolling temperature conditions, copper alloy samples having the composition shown in Example 1 were prepared under different hot rolling temperature conditions, and then the physical properties of the copper alloy samples were evaluated.

It can be confirmed from Table 3 that when the hot rolling temperature is lower than 900°C, the characteristics of the copper alloy according to the present invention cannot be exhibited. The second graphs A to C show the results of Table 3. The second figure A shows a copper alloy prepared by hot rolling at a temperature of 870°C, which corresponds to the general hot rolling conditions of the copper alloy of the lead frame; observation of the copper alloy after hot rolling reveals that the processing structure remains (Rolled structure), which affects the subsequent process and causes the characteristics of the final product to decrease. In the copper alloys in the second B and second C diagrams, the hot rolling temperature is 900 C or higher, so that an anisotropic recrystallized structure is formed after hot rolling, and can exhibit the characteristics of the copper alloy according to the present invention.

In order to confirm the average crystal grain size and microstructure of the copper alloy according to the present invention, the third figure shows the FE-SEM photograph of the copper alloy sample prepared according to the composition of Example 5. As exemplified in the third graph, the average crystal grain size of the sample of Example 5 was 20 μm or less, and its standard deviation was 5 μm or less. From these results, it can be confirmed that the copper alloy according to the present invention has a good microstructure, and thus can be used in electrical and electronic components and semiconductors without any problems (such as surface defects).

The analysis results of the copper alloy sample of Example 5 using FE-TEM are shown in the fourth graph A and the fourth graph B.

Fig. 4A is an FE-TEM photograph of a sample prepared by generally used ion milling method to confirm the precipitates in the copper alloy having the composition of Example 5, and in this EE-TEM photograph, it is difficult to confirm The presence of precipitates in the copper alloy and whether the precipitates are distributed in the copper alloy makes it difficult to analyze accurately. In order to solve these problems, a new analysis method must be adopted.

In order to overcome the limitations of the traditional ion milling method, Figure 4B is a FE-TEM photograph of the sample prepared by the carbon extraction repeat method to confirm the precipitates in the copper alloy having the composition of Example 5. If you observe the sample prepared by the carbon extraction repeat method, you can accurately analyze the shape, size, composition, area density, etc. of fine precipitates. Only the presence of precipitates can be confirmed from the fourth picture A, but from the fourth picture B it can be confirmed that (FeMn) ₂ P (not observed in the traditional Cu-Fe-P group) is uniformly formed and its average particle size It is 50 nm or less, and the area density is 1.0*10 ¹⁰ /cm ² or more.

Claims (8)

A copper alloy for electrical and electronic components and semiconductors, including: iron (Fe) in a mass ratio of 0.09 to 0.20%, phosphorus (P) in a mass ratio of 0.05 to 0.09%, and manganese in a mass ratio of 0.05 to 0.20% (Mn), the remaining content of copper (Cu) and the inevitable impurities with a mass ratio of 0.05% or less, the inevitable impurities include from silicon (Si), zinc (Zn), calcium (Ca), aluminum At least one selected from the group consisting of (Al), titanium (Ti), beryllium (Be), chromium (Cr), cobalt (Co), silver (Ag) and zirconium (Zr); and (FeMn) ₂ P precipitates, wherein: the (FeMn) ₂ P precipitates are obtained by using a high-resolution transmission electron microscope (HR-TEM) or a field emission transmission electron microscope (FE-TEM) at 100,000x or more The magnification observation is measured by a sample prepared by the carbon extraction and replication method, and has an average particle size ranging from 27 nm to 50 nm, and an area density of 1.0*10 ¹⁰ /cm ² or higher; and the copper alloy has 470 MPa or Higher tensile strength, hardness of 145Hv or higher, conductivity above 75% IACS, and softening temperature resistance of 400°C or higher. The copper alloy for electrical and electronic components and semiconductors as described in item 1 of the scope of the patent application, wherein the impurities have a content of 0.01% or less by mass. The copper alloy for electrical and electronic components and semiconductors as described in item 1 of the scope of the patent application further includes at least one of nickel (Ni) or tin (Sn) with a mass ratio of 0.0001 to 0.03%. A copper alloy for electrical and electronic components and semiconductors as described in item 1 of the patent application scope, wherein the copper alloy has an average grain size of 20 μm or less and a standard deviation of grain size of 5 μm or less, It was measured by crystal orientation analysis using a field emission scanning electron microscope (FE-SEM). The copper alloy for electrical and electronic components and semiconductors as described in item 1 of the patent application scope, wherein the copper alloy is prepared as a sheet or a plate. A method for preparing a copper alloy for electrical and electronic components and semiconductors, comprising: melting the constituent elements described below to cast an ingot: iron (Fe) with a mass ratio of 0.09 to 0.20% and a mass ratio of 0.05 to 0.09% phosphorus (P), 0.05 to 0.20% mass ratio of manganese (Mn), residual content of copper (Cu), and 0.05% or lower mass ratio of inevitable impurities, the inevitable impurities Including from silicon (Si), zinc (Zn), calcium (Ca), aluminum (Al), titanium (Ti), beryllium (Be), chromium (Cr), cobalt (Co), silver (Ag) and zirconium ( Zr) at least one selected from the group consisting of: ingots obtained by homogenizing heat treatment at a temperature of 900 to 1000°C for 1 to 4 hours, and then hot rolled at a processing rate of 85 to 95%; 87 to 98% processing rate cold rolling the product obtained in the previous step; precipitation heat treatment of the product obtained in the previous step at a temperature of 430 to 520°C for 1 to 10 hours; and a reduction rate of 10 to 90% rolling the product obtained in the previous step, to produce a final product, obtained by preparing a copper alloy that comprises (FeMn) ₂ P precipitates, the (FeMn) ₂ P-based precipitates penetration by use of a high-resolution Electron microscope (HR-TEM) or field emission transmission electron microscope (FE-TEM) at a magnification of 100,000x or more to observe a sample prepared by the carbon extraction and replication method to measure, and the average particle size is At 27nm to 50nm, the area density is 1.0*10 ¹⁰ /cm ² or higher; and the copper alloy has a tensile strength of 470MPa or higher, hardness of 145Hv or higher, conductivity of 75% IACS or higher, and 400℃ Or higher softening resistance temperature. A method for preparing a copper alloy for electrical and electronic components and semiconductors, comprising: melting the constituent elements described below, casting an ingot with a mass ratio of 0.09 to 0.20% iron (Fe), and a mass ratio of 0.05 Phosphorus (P) to 0.09%, manganese (Mn) with a mass ratio of 0.05 to 0.20%, copper (Cu) with a residual content, and inevitable impurities with a mass ratio of 0.01% or less. The inevitable impurities include From silicon (Si), zinc (Zn), calcium (Ca), aluminum (Al), titanium (Ti), beryllium (Be), chromium (Cr), cobalt (Co), silver (Ag) and zirconium (Zr) ) At least one selected from the group consisting of: homogenizing the ingot obtained by heat treatment at a temperature of 900 to 1000°C for 1 to 4 hours, and then hot rolling at a processing rate of 85 to 95%; 87 Cold rolling of the product obtained in the previous step to a processing rate of up to 98%; precipitation heat treatment of the product obtained in the previous step at a temperature of 430 to 520°C for 1 to 10 hours; and rolling at a reduction rate of 10 to 90% manufactured product obtained in the previous step, to produce a final product, obtained by preparing a copper alloy that comprises (FeMn) ₂ P precipitates, the (FeMn) ₂ P-based precipitates by using a high-resolution transmissive Electron microscopy (HR-TEM) or field emission transmission electron microscopy (FE-TEM) was observed at a magnification of 100,000x or more to observe a sample prepared by the carbon extraction and replication method, and the average particle size is between 27nm to 50nm, area density is 1.0*10 ¹⁰ /cm ² or higher; and the copper alloy has a tensile strength of 470MPa or higher, hardness of 145Hv or higher, conductivity above 75% IACS, and 400℃ or Higher resistance to softening temperature. A method for preparing a copper alloy for electrical and electronic components and semiconductors, comprising: melting the constituent elements described below, casting an ingot with a mass ratio of 0.09 to 0.20% iron (Fe), and a mass ratio of 0.05 At least one of phosphorus (P) to 0.09%, manganese (Mn) at a mass ratio of 0.05 to 0.20%, nickel (Ni) or tin (Sn) at a mass ratio of 0.0001 to 0.03%, and the remaining content of copper (Cu) And inevitable impurities with a mass ratio of 0.05% or less, the inevitable impurities include from silicon (Si), zinc (Zn), calcium (Ca), aluminum (Al), titanium (Ti), beryllium ( At least one selected from the group consisting of Be), chromium (Cr), cobalt (Co), silver (Ag), and zirconium (Zr); ingots obtained by homogenizing heat treatment at a temperature of 900 to 1000°C Up to 1 to 4 hours, then hot rolling at a processing rate of 85 to 95%; cold rolling the product obtained at the previous step at a processing rate of 87 to 98%; at a temperature of 430 to 520°C Products are subjected to precipitation heat treatment for 1 to 10 hours; and rolling the products obtained in the previous step at a reduction rate of 10 to 90% to produce a final product, the prepared copper alloy includes (FeMn) ₂ P precipitates The (FeMn) ₂ P precipitate is observed by using a high-resolution transmission electron microscope (HR-TEM) or a field emission transmission electron microscope (FE-TEM) at a magnification of 100,000x or more It is measured by a sample prepared by the carbon extraction and replication method, and has an average particle size ranging from 27 nm to 50 nm, and an area density of 1.0*10 ¹⁰ /cm ² or higher; and the copper alloy has a tensile strength of 470 MPa or higher Strength, hardness of 145Hv or higher, conductivity above 75% IACS, and softening resistance temperature of 400°C or higher.

Images