KR101834335B1 - Copper alloy for electrical and electronic parts and semiconductor with high strength and high electrical conductivity and a method of preparing same - Google Patents

Abstract

The present invention relates to a copper alloy for electrical and electronic parts and a semiconductor with high strength and high electrical conductivity, and a method of preparing the same. According to the present invention, the copper alloy comprises: 0.09-0.20 % by mass of iron (Fe); 0.05-0.09 % by mass of phosphorus (P); 0.05-0.20 % by mass of manganese (Mn); and the remainder consisting of copper (Cu) and an amount of 0.05 % or less by mass of inevitable impurities. Moreover, the copper alloy has tensile strength more than 470 MPa, hardness more than 145 Hv, and electrical conductivity more than 75% IACS, and the internal combustion temperature is more than 400°C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy for electrical and electronic parts and a semiconductor having high strength and high electric conductivity and a method for manufacturing the copper alloy.

TECHNICAL FIELD The present invention relates to a copper alloy for electrical and electronic parts and semiconductors having high strength and high electrical conductivity, and a method for manufacturing the same. More particularly, the present invention relates to a copper alloy including copper (Cu), iron (Fe), phosphor (P), and manganese (Mn)

A Cu-Fe-P alloy containing Fe and P is generally used as a copper alloy for various purposes including a semiconductor lead frame, a material for electric and electronic parts, and the like. For example, a copper alloy (C19210) containing Fe in an amount of 0.05 to 0.15% and P in an amount of 0.025 to 0.04%, Fe in an amount of 2.1 to 2.6%, P in an amount of 0.015 to 0.15%, and Zn in an amount of 0.05 to 0.2% One copper alloy (C19400) is widely used as a lead frame material because of its excellent strength and electrical conductivity among copper alloys. The reason why Fe and P are mainly used as an additive element is that they form a precipitate phase in a copper matrix and exhibit excellent strength and electric conductivity.

However, among the various characteristics of the copper alloy, the strength and the electrical conductivity are inversely proportional to each other. As the strength increases, the electrical conductivity decreases. When the electrical conductivity increases, the decrease in strength is inevitable. Therefore, the existing C19210 copper alloy has a tensile strength of 400MPa and an electrical conductivity of 80% IACS. Therefore, it is used in products that require high electrical conductivity because of low strength but low electrical conductivity. The existing C19400 copper alloy has tensile strength of 500MPa, Since the conductivity is 60% IACS level, the electric conductivity is low but it has been used in products requiring high strength because of excellent strength characteristics.

Recently, the characteristics of materials have become more important due to the thinning and shortening of electric and electronic parts. BACKGROUND ART [0002] With the trend toward larger capacity, smaller size, and higher integration of semiconductor devices used in electronic devices, vehicles, and the like, miniaturization and thinning of lead frames used in semiconductors are progressing. Therefore, the present copper alloy has to satisfy both high strength, high electrical conductivity and excellent workability at the same time as the conventional copper alloy. As the thickness of the electronic component becomes thinner, the copper alloy of the application has a tensile strength of 470 MPa or more And electrical conductivity of 75% IACS or higher at the same time. Therefore, in order to meet the demands of the industry, efforts have been made to simultaneously improve strength and electric conductivity, which are opposite characteristics.

In order to increase the strength of the copper alloy, the content of Fe and P is increased or a third element such as Sn, Mg or Ni is added. However, if the amount of these elements is increased, the strength is increased but the electrical conductivity is lowered. As a result, efforts have been made to improve the properties by finely graining grains instead of added elements or controlling the size and distribution of the precipitates. However, also in this case, various problems such as occurrence of surface defects, lowered reliability, and uneven microstructure occur. Therefore, it is difficult and important to improve both the strength and electrical conductivity of the copper alloy.

In addition, in the field where copper alloy material is applied, since the process of applying heat is included, the copper alloy needs to have heat resistance property, which is called an anti-softening property and can be evaluated by the softening temperature. The softening temperature refers to the heat treatment temperature which represents 80% of the initial (before heat treatment) hardness value when the hardness value changed after heat treatment for 1 minute is measured. The softening temperature is used as an indicator of the characteristics of the material that can withstand heat and is linked to the reliability of the finished article as described above. Conventional semiconductor In the case of package or electronic parts, the softening temperature characteristic of 380 ° C did not cause a serious problem in the manufacture of the product and the reliability of the final product. However, recently, copper alloy to be applied to semiconductor packages, electronic parts, and the like is required to have excellent softening resistance at the time of product processing, such as adding a heat applying process such as soldering or wire bonding at the time of product processing, It is necessary to improve the softening resistance at a temperature of 400 DEG C or higher.

Until now, various patents have been filed for obtaining the strength and electric conductivity required for the lead frame copper alloy material.

In Korean Patent Laid-Open No. 10-2008-0019274, Mg is added to a Cu-Fe-P alloy to improve the strength. However, when Mg is added, the electric conductivity inevitably deteriorates. When Mg is added to conventional Cu-Fe-P alloys, the tensile strength is up to 450MPa and the electric conductivity is 70% IACS. It is less than the required characteristics of lead frame (tensile strength 470MPa or more and electric conductivity 75% IACS or more) , Which is explained by Mg-P coarse crystallization. It is inevitable that the strength and electrical conductivity characteristics are deteriorated due to Mg-P coarse depressions and defect formation inevitably generated from the start of casting to the end of hot rolling when Mg is added.

Next, in Korean Patent Publication No. 10-2005-0076767, the particle size of the precipitate of the Cu-Fe-P alloy was controlled to improve the strength. However, since the present invention carries out cold rolling and annealing two times or more in order to finely control the particle size of the precipitate, various variables exist and it is difficult to actually manufacture in the industrial field. In addition, although the volume of the precipitate is described as 1% or more and 300 pieces / 탆 ² in the above patent documents, there is a problem that the volume fraction contains coarse particles.

On the other hand, Korean Patent Laid-Open Publication No. 10-2013-0136183 discloses that Mn is added to a Cu-Fe-P based alloy to improve strength, but the strength and electric conductivity characteristics required in actual industrial fields are not satisfied. In addition, although the control of the particle size of the precipitate to a size of 10 to 30 mu m has been described in claim 4 of the patent document, in reality, the size of 10 to 30 mu m is too large to be a casting defect or a foreign substance, It can not have an effect. In this regard, in general, when a particle having a size of 10 to 30 탆 is present in a copper alloy, the semiconductor packaging process is impossible due to the deterioration of the surface quality as well as the deterioration of the characteristics. In addition, there is no analytical result or evidence that the disclosed precipitates can define what kind of precipitates, and in the SEM analysis results of FIG. 3, only simple grain boundaries are observed, not precipitates, which can not be a technical basis.

Disclosure of the Invention The present invention has been made to solve the above problems and it is an object of the present invention to provide a copper alloy for electric and electronic parts and semiconductors having strength and electrical conductivity of a level that satisfies the requirements of industry in recent years, Method.

According to the invention, The electric or electronic parts or the copper alloy for semiconductors (Cu) and 0.05 mass% or less of copper (Cu), respectively, in an amount of 0.09 to 0.20% of iron (Fe), 0.05 to 0.09% of phosphorus (P) and 0.05 to 0.20% of manganese At least one kind selected from the group consisting of Si, Zn, Ca, Al, Ti, Be, Cr, Co, Ag and Zr; a tensile strength of 470 MPa or more; a hardness of 145 Hv or more; An electrical conductivity of at least IACS, and a softening temperature characteristic of 400 DEG C or higher. The content of the unavoidable impurities is preferably 0.01% or less. The copper alloy may further include at least one of Ni and Sn in a range of 0.0001% to 0.03%.

The copper alloy has an average crystal grain size of 20 占 퐉 or less and a standard deviation of 5 占 퐉 or less at a crystal grain size measured by a crystal orientation analysis method using a field emission scanning electron microscope (FE-SEM).

The copper alloy includes (FeMn) ₂ P precipitate. The precipitate Carbon extraction replica (carbon extraction replica) method is determined with a ratio more than 100,000 times the specimens prepared in a high-resolution transmission electron microscopy (HR-TEM) or a field emission transmission electron microscope (FE-TEM), the (FeMn) ₂ P The precipitate has an average particle diameter of 50 nm or less and a surface density of 1.0 x 10 ¹⁰ / cm ² or more.

The copper alloy may be in the form of a sheet or a sheet metal.

According to the invention, The method for producing an electric or electronic component or a copper alloy for semiconductor includes the steps of casting an ingot by dissolving the above-mentioned constituent elements, subjecting the obtained ingot to homogenization heat treatment at 900 ° C. to 1000 ° C. for 1 to 4 hours, To 95%, a cold rolling step at a reduction rate of 87 to 98%, a precipitation heat treatment at a temperature of 430 to 520 DEG C for 1 to 10 hours, and a final rolling at a reduction rate of 10 to 90% .

The copper alloy according to the present invention is excellent in strength and electrical conductivity and excellent in softening resistance. In addition, despite the reduction of the process cost in the production of the copper alloy through the manufacturing process according to the present invention, the copper alloy obtained exhibits excellent strength and electrical conductivity and can be applied to discrete transistors or discrete TRs, Applicable to electronic parts.

FIG. 1 is a graph showing the softening resistance characteristics of a copper alloy and an existing copper alloy manufactured according to Example 5. FIG.
2A is a FE-SEM photograph showing microstructure after hot rolling at 870 캜 in a process of producing a copper alloy having the composition described in Example 1. Fig.
FIG. 2B is an FE-SEM photograph for confirming the microstructure after hot rolling at 900 ° C. in a process for producing a copper alloy having the composition described in Example 1. FIG.
FIG. 2C is an FE-SEM photograph for confirming the microstructure after hot rolling at 950 ° C. in the process of manufacturing a copper alloy having the composition described in Example 1. FIG.
3 is an FE-SEM photograph for confirming the microstructure of the copper alloy produced according to Example 5. Fig.
Fig. 4A is an FE-TEM photograph of a specimen produced by ion milling to confirm the precipitate of the copper alloy having the composition described in Example 5. Fig.
4B is an FE-TEM photograph of a specimen produced by a carbon extraction replica method to confirm the precipitate of the copper alloy having the composition described in Example 5. Fig.

The present invention provides an electrical and electronic component and a copper alloy for semiconductor which have excellent strength and electric conductivity and excellent resistance to softening, and a method for producing the same. In the present specification, the% indicating the content of the constituent element is, unless otherwise indicated,% by mass.

The copper alloy according to the present invention

The copper alloy according to the present invention contains 0.09 to 0.20% of iron (Fe), 0.05 to 0.09% of phosphorus (P), 0.05 to 0.20% of manganese (Mn) And the inevitable impurities are at least one species selected from the group consisting of Si, Zn, Ca, Al, Ti, Be, Cr, Co, Ag, and Zr and have a tensile strength of 470 MPa or more, , Electric conductivity of 75% IACS or more, and softening resistance of 400 DEG C or more.

Hereinafter, the composition of the copper alloy according to the present invention will be described. In the present specification, the percentage of the content of elements is expressed in mass% unless otherwise stated.

[Fe]

Fe is an element necessary to form fine (FeMn) ₂ P precipitates and to improve strength and conductivity. The content of Fe is in the range of 0.09 to 0.20%. If it is contained in an amount less than 0.09%, the effect of inhibiting the growth of crystal grains due to the precipitate is reduced because the particles required for the formation of the precipitate are insufficient. As a result, the average crystal grain size or the standard deviation of the average crystal grain size becomes too large and the strength decreases. Therefore, in order to effectively exhibit these effects, a content of 0.09% or more is required. However, if it is contained in an excess amount exceeding 0.20%, coarsening of the precipitate is caused, and the standard deviation of the average crystal grain size is excessively large, so that the bending workability is lowered and the electric conductivity is lowered.

[P]

P, in addition to a deoxidation effect, and in combination with Fe, Mn form a (FeMn) ₂ P fine precipitates, thereby improving the strength of the copper alloy or the electrical conductivity. The content of P is 0.05 to 0.09%. If the content of P is less than 0.05%, the formation of fine precipitates is insufficient and the effect of inhibiting the growth of crystal grains due to precipitates becomes small. As a result, the average crystal grain size or the standard deviation of the average crystal grain size becomes too large and the strength decreases. Therefore, a content of 0.05% or more is required. However, if it exceeds 0.09%, the standard deviation of the average crystal grain size becomes too large as the coarse precipitated particles increase, and the bending workability decreases. Also, the electric conductivity is lowered.

[Mn]

Mn is usually reported to contribute to strength improvement when a copper alloy is added, but when Mn is simply added to increase the strength, the electrical conductivity of the finally obtained copper alloy is inevitably lowered. By forming the (FeMn) ₂ P precipitate in the copper alloy according to the present invention, it is possible to improve the strength and the electric conductivity at the same time. The content of Mn in the copper alloy of the present invention is 0.05 to 0.20%. When the content of Mn is less than 0.05%, formation of precipitates is insufficient and the effect of inhibiting grain growth is reduced and the strength is lowered similarly to Fe described above. If it exceeds 0.20%, both the strength and the electric conductivity are lowered due to coarse crystallization or casting defects.

[Inevitable impurities]

The copper alloy of the present invention contains at least one selected from the group consisting of Si, Zn, Ca, Al, Ti, Be, Cr, Co, Ag and Zr in an amount of 0.05% or less. Preferably, the addition amount is 0.01% or less. These elements serve to improve various characteristics of the copper alloy, and it is preferable to selectively add them depending on the application.

On the other hand, in the case of the copper alloy according to the present invention, in the case of magnesium (Mg), which is generally known as one having excellent strengthening effect, the strength of the copper alloy finally obtained at the time of addition is somewhat improved but the electrical conductivity is inevitably degraded, From the start to the end of hot rolling, Mg-P coarse precipitates and defects are caused, so they should be excluded.

[Ni] and [Sn]

At least one of Ni and Sn in an amount of 0.0001% to 0.03%. Ni has an effect of being strengthened in solid solution by being employed in a Cu base, and is an effective element for heat resistance. When it is 0.0001% or less, the strength improvement effect can not be obtained. On the other hand, when it is added in excess of 0.03%, the electrical conductivity is lowered.

Sn is a solid solution strengthening alloy having an effect of improving strength by being dissolved in a Cu matrix. When it is less than 0.0001%, strength improvement effect is hardly expected, and when it exceeds 0.03%, electrical conductivity is lowered.

The characteristics of the copper alloy according to the present invention

In general, it is very difficult to control the two properties because copper alloy tends to decrease in electrical conductivity with increasing strength.

The strength of the copper alloy according to the present invention can satisfy both a tensile strength of 470 MPa or more and a hardness of 145 Hv or more. This is a numerical value that reflects the characteristics of the industry in recent years. It is a characteristic of the limit value in consideration of the strength of the copper alloy exhibiting the inverse characteristic and the electrical conductivity characteristic.

In addition, the electrical conductivity of the copper alloy used for semiconductors or electric / electronic components should be 75% IACS or higher. If the electrical conductivity is less than that, the electrical signal transmission is not smooth and can not be used in the product. The electrical conductivity of the copper alloy according to the present invention is at least 75% IACS.

That is, the copper alloy according to the present invention surprisingly exhibits excellent properties in which strength and electrical conductivity characteristics are simultaneously improved.

The copper alloy according to the present invention also has an excellent softening temperature of 400 DEG C or higher. The description of the softening temperature is described below in the process for producing a copper alloy according to the present invention.

A method for producing a copper alloy according to the present invention

The copper alloy according to the present invention can be produced according to the production method described below. First, the ingot is cast by dissolving the constituent elements according to the above-mentioned composition. The obtained ingot is hot-rolled at a machining rate of 85 to 95% immediately after homogenizing heat treatment at 900 to 1000 占 폚 for 1 to 4 hours. The hot rolling is terminated and water-cooling is performed to solidify the solute elements, and cold rolling is performed at a working rate of 87 to 98%. After the high rolling energy is accumulated by the cold rolling, the driving force for precipitate formation is increased, and the heat treatment is performed at 430 to 520 ° C for 1 to 10 hours. Followed by a final rolling at a reduction rate of 10 to 90% to determine the final thickness of the product.

Specifically, each step of the above-described method for producing a copper alloy according to the present invention will be described.

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

Then, the obtained ingot is subjected to homogenization heat treatment at 900 to 1000 ° C for 1 to 4 hours, followed by hot rolling at a machining rate of 85 to 95%. Homogenization heat treatment is a necessary process for hot rolling, in which the ingot is not cold worked but hot-rolled in a sufficiently heated state to remove the casting structure and make a new recrystallized structure. The hot rolling step is the most important step in the process for producing the copper alloy according to the present invention. The hot rolling condition is a factor that has an important influence on the metal structure among the alloy characteristics, and the hot rolled condition causes different tissues after hot rolling, and thus the properties of the finished product are different. The hot rolling conditions include hot rolling temperature, hot rolling pass number, cooling condition, and the like, and the structure obtained after hot rolling is different depending on each condition.

In order 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 占 폚. When the temperature is in the hot rolling temperature range, an isotropic recrystallized structure having no directionality can be obtained. As can be seen from the examples described later, when the hot rolling temperature is lower than 900 DEG C, the processed structure (rolled structure) remains. In the case of conventional copper alloy for lead frame, it is necessary to add at least one solution treatment and precipitation process in order to prevent deterioration of final finished product, which leads to an increase in process cost and a decrease in productivity. On the other hand, in the case of the copper alloy according to the present invention, since the characteristics are exhibited without such additional process, the process cost can be saved and the productivity can be improved.

When heated for a homogenization heat treatment for 1 to 4 hours at a temperature range of 900 to 1000 ° C, the solution treatment effect is obtained simultaneously with the isotropic recrystallized structure obtained. If heated to less than 1 hour, the localized structure remains and the characteristics of the isotropic recrystallized structure can not be completely displayed. In the case of exceeding 4 hours, the ingot may partially dissolve. The solution treatment process is a process of supersaturated element having solubility in a Cu matrix to maximize the effect of precipitation. In general precipitation hardened alloy, an additional solution solution process is carried out at a thin plate thickness, so that the process cost is increased and the productivity is decreased. However, the copper alloy according to the present invention obtains the effect of solution treatment through heat treatment in the hot rolling step, and then, in the cold rolling step, high strain energy can be accumulated in the material through 87 to 98% coercive force. The high strain energy remaining in the material becomes a driving force for the precipitation process after the cold rolling, making it possible to evenly distribute fine precipitates in the precipitation process.

Next, the hot rolling is terminated and water-cooling is performed to solidify the solute elements, and the solution is cold-rolled at a working rate of 87 to 98%. It is possible to accumulate high strain energy by the cold rolling to increase the driving force for precipitate generation.

Subsequently, heat treatment is performed at 430 to 520 ° C for 1 to 10 hours. The copper alloy according to the present invention is a precipitation hardening type alloy, and the precipitation process is very important. The copper alloy according to the present invention is designed to be a new copper alloy to which Mn is added. However, since Mn can not be accompanied by optimum strength and electrical conductivity, it is possible to uniformly disperse fine precipitates through a precipitation process. In the case of the conventional Cu-Fe-P type alloy, mainly Fe ₂ P precipitate exists in the copper alloy, and locally coarse FeP precipitate exists, which deteriorates the characteristics. On the other hand, in the process for producing a copper alloy according to the present invention, fine iron (FeMn) ₂ P precipitates are dispersed in the copper alloy by precipitation heat treatment under the above conditions, thereby achieving both high strength and high electrical conductivity.

Finally, the finished product is rolled at a reduction ratio of 10 to 90%. Finished rolling by cold rolling with a machining ratio of 10 to 90% to secure the target properties. At this time, the range of the preferable machining rate is 30 to 70%, and in this range, the efficiency of the increase in the strength with respect to the machining amount of the alloy of the invention is the highest.

In addition, in the above method, after the precipitation heat treatment and before the final finished rolling, intermediate heat treatment can be carried out after cold rolling with a machining rate of 30 to 90% as required. The cold rolling and intermediate heat treatment step with a machining rate of 30 to 90% can be carried out by a process such as a mass production line heat treatment facility, a pickling process (partial bonding by heat and pressure) or a surface pickling process And it is not a necessary process to solve the surface quality problems such as scratches caused by the above. The intermediate heat treatment can be applied to cases where the product thickness after the precipitation heat treatment and the thickness after the finished rolling are large and the target properties (strength, electric conductivity) are out of range or the target characteristics are difficult to secure. In this case, it is important to heat treat the intermediate heat treatment so as to reduce the electric conductivity within the range of 0.1 to 3% IACS, since the reduction of the electric conductivity should be minimized for the purpose of reducing the strength. If the electrical conductivity is less than 0.1% IACS, the heat treatment is not effective. If the electrical conductivity is lower than 3% IACS, the effect of heat treatment is large. However, There is a possibility to escape.

In the process for producing a copper alloy according to the present invention, the hot rolling and the precipitation heat treatment step have an important influence on the characteristics of the final copper alloy obtained. In order to distribute fine FeMn ₂ P precipitates in the copper alloy according to the present invention, It is necessary to precisely control the manufacturing process sequentially. FE-SEM and FE-TEM observations are essential to identify the fine precipitates produced in the copper alloy.

Prepared according to the method of manufacturing the copper alloy according to the present invention, the copper alloy is fine (FeMn) ₂ when including P precipitate and observing the microstructure of at least 100,000-fold magnification by the crystal orientation analysis method using an FE-TEM, (FeMn) ₂ The average particle size of the P precipitate is 50 nm or less and the surface density is 1.0 x 10 ¹⁰ / cm ² or more.

In order to observe precipitates, TEM samples of conventional ion milling methods were conventionally prepared, but it is impossible to observe fine precipitates having a size of several to several tens of nanometers with such specimens. Even if an attempt is made to observe fine precipitate particles, it is difficult to distinguish impurities or foreign substances from precipitates in a TEM specimen produced by the ion milling method, and the crystal structure and composition of the precipitate can not be confirmed. On the other hand, it is possible to observe the fine precipitates of the copper alloy according to the present invention by TEM analysis of the specimen produced by the carbon extraction replica method.

In the copper alloy according to the present invention, fine (FeMn) ₂ P precipitates are uniformly distributed in the grain boundaries and in the mouth, and the average particle diameter of the (FeMn) ₂ P precipitates is 50 nm or less. If the average particle diameter of the precipitate is more than 50 nm, the decrease of the electrical conductivity is inevitable and may cause a problem of lack of reliability in the semiconductor process. The average particle diameter of the precipitate is, for example, (FE-TEM) crystal orientation analysis method at a magnification of 100,000 times or more. In this regard, in the examples described below, the FE-TEM analysis results of the copper alloy according to the present invention are shown in Figs. 4A and 4B.

It is also possible to measure the area density based on the FE-TEM results as disclosed in Figures 4A and 4B. The surface density is the number of existing precipitates within a certain area range, and is a measure for estimating the dispersion of the precipitates. In the past, the volume fraction was used to estimate the dispersion of precipitates. However, since the volume fraction represents the ratio of the precipitates within a certain range, the error range is considerable when very large coarse particles are generated. On the contrary, when the concept of face density is used, the presence of coarse particles does not affect the numerical value of the area density, and the degree of dispersion of the precipitate can be confirmed more accurately. The area density of the copper alloy according to the present invention is 1.0 x 10 ¹⁰ / cm ² or more. Since the average particle diameter of the (FeMn) ₂ P precipitate of the copper alloy according to the present invention is as small as 50 nm or less, In order to exhibit the characteristics of the inventive alloy, it is necessary to form a large amount of precipitates, and when the number of precipitates, that is, the area density is 1.0 x 10 ¹⁰ / cm ² or less, sufficient strength can not be exhibited.

The softening temperature of the copper alloy according to the present invention is 400 占 폚 or higher. In order to exhibit sufficient resistance to softening properties in electrical and electronic components and semiconductor applications, the softening temperature should be at least 400 ° C. The present invention is excellent in anti-softening property by performing precipitation strengthening instead of grain refinement as a means for improving the strength of the copper alloy. If the grain refinement is performed for grain refinement, softening failure may occur due to high internal stress. The softening defect is caused by softening of the material hardness due to processing of the material and heat during the semiconductor packaging, thereby causing defective product.

The electric electronic part or the copper alloy for semiconductor according to the present invention can be produced in the form of a sheet or a plate. The sheet or sheet form is suitable for application to semiconductors or IC lead frames or connectors and terminals.

As described above, the copper alloy according to the present invention has a superior strength and electrical conductivity at the same time as that of conventional products by combining the composition of the copper alloy and controlling the manufacturing process precisely. Further, the copper alloy has excellent resistance to softening, The present invention is particularly suitable for discrete transistors which are automotive power control semiconductors in recent years in addition to electric and electronic components such as lead frames, terminals, connectors, switches, and relays.

Example

Example  1 to 16

The specimens of Examples 1 to 16 were prepared with the compositions shown in Table 1. The method of preparing the specimen is as described below.

Alloying elements containing copper were mixed on the basis of the composition disclosed in Table 1 on a 1 kg basis and dissolved in a high-frequency melting furnace to produce ingots each having a thickness of 20 mm, a width of 50 mm and a length of 160 to 180 mm. The ingot was cut 20 mm each at the bottom and top of the ingot in order to remove defective parts such as rapid cooling and shrinkage cavity and then the ingot was cast into a box at 900 ° C. And subjected to a homogenization heat treatment in a box furnace for 2 hours to conduct hot rolling at a machining ratio of 90%. In order to prevent precipitation of solute elements at the same time as the hot rolling was completed, Prior to the precipitation step, high strain energy was accumulated by cold rolling at a machining rate of 90% to increase the driving force for precipitate formation, followed by precipitation heat treatment at 450 占 폚 for 3 hours and finish by cold rolling at a machining rate of 50%. Finally, the finished rolled copper alloy was prepared as a specimen of 0.3t x 30w x 200L and used in subsequent tests. Table 2 shows the results of the characteristic analysis described in the test examples of the copper alloy specimens produced according to Examples 1 to 16.

Comparative Example  1 to 16

The specimens of Comparative Examples 1 to 16 were produced by the manufacturing process under the same conditions as in Examples 1 to 16 with the compositions shown in Table 1. Table 2 also shows the analysis results of the characteristics of the copper alloy specimens prepared according to Comparative Examples 1 to 16.

division Chemical Composition of Copper Alloy (wt%) Cu Fe P Mn Ni Sn impurities Example 1 Remainder 0.09 0.05 0.05 - - - Example 2 Remainder 0.09 0.05 0.10 - - - Example 3 Remainder 0.09 0.05 0.15 - - - Example 4 Remainder 0.12 0.06 0.05 - - - Example 5 Remainder 0.12 0.06 0.10 - - - Example 6 Remainder 0.12 0.06 0.15 - - - Example 7 Remainder 0.12 0.06 0.12 - - - Example 8 Remainder 0.15 0.08 0.05 - - - Example 9 Remainder 0.15 0.08 0.10 - - Si 0.005 Example 10 Remainder 0.15 0.08 0.15 - - - Example 11 Remainder 0.15 0.09 0.05 - - - Example 12 Remainder 0.15 0.09 0.10 - - - Example 13 Remainder 0.15 0.09 0.15 - - - Example 14 Remainder 0.20 0.09 0.10 0.01 - - Example 15 Remainder 0.20 0.09 0.15 - 0.02 - Example 16 Remainder 0.20 0.09 0.20 0.01 0.01 - Comparative Example 1 Remainder 0.12 0.04 - - - - Comparative Example 2 Remainder 0.08 0.04 0.01 - - - Comparative Example 3 Remainder 0.08 0.04 0.05 - - - Comparative Example 4 Remainder 0.08 0.04 0.10 - - - Comparative Example 5 Remainder 0.10 0.03 0.01 - - - Comparative Example 6 Remainder 0.10 0.03 0.05 - - - Comparative Example 7 Remainder 0.10 0.03 0.10 - - - Comparative Example 8 Remainder 0.12 0.04 0.05 - - - Comparative Example 9 Remainder 0.12 0.04 0.10 - - - Comparative Example 10 Remainder 0.12 0.04 0.15 0.01 - - Comparative Example 11 Remainder 0.12 0.04 0.20 - - - Comparative Example 12 Remainder 0.15 0.04 0.10 - 0.01 - Comparative Example 13 Remainder 0.15 0.04 0.20 - 0.03 - Comparative Example 14 Remainder 0.15 0.10 0.10 0.03 - - Comparative Example 15 Remainder 0.25 0.06 0.20 0.01 0.01 - Comparative Example 16 Remainder 0.25 0.06 0.25 - - -

Examples 1 to 14 are examples for evaluating the critical meaning of the composition range of Cu, Fe, Mn, and P, and are shown in Table 1. Examples 14 to 16 are examples for confirming the effect of Ni and Sn added elements.

The component of Comparative Example 1 has the same composition as that of the C19210 alloy widely used for lead frames. In Comparative Examples 8 to 13, Mn was added to the existing C19210 alloy.

Test Example

Hereinafter, a method for analyzing the characteristics of the copper alloy specimen produced according to the above-described embodiments and comparative examples will be described.

The tensile strength was measured using a Z100 universal testing machine from ZWICK ROELL. The hardness was measured with a TUKON 2500 Vickers hardness tester from INSTRON Co., Ltd. under a load of 1 kg and the electrical conductivity was measured using SIGMATEST from FOERSTER.

In the softening temperature analysis, heat treatment was carried out using THERMO SCIENTIFIC Thermolyne 5.8L D1 Benchtop Muffle Furnace. Specifically, the softening temperature was calculated by heating the specimen at 300/350/400/450/500/550/600/650/700 ° C for 1 minute, - A plot of temperature (X-axis) plotted to plot the temperature values intersecting 80% of the initial hardness value. The results are shown in FIG. 1 by comparing the inventive alloys of Example 5 with conventional C19400 and C19210 alloys.

The mean grain size of the microstructure of the sample was measured using FEIA's Quanta 650 FEG (FE-SEM). In order to measure the average grain size, the surface of the specimen was polished and charged into the FE-SEM chamber. The degree of vacuum in the chamber was maintained at 1 × 10 ^-5 torr or less, and then the ion beam was irradiated and observed by the crystal orientation analysis method. Fig. 3 shows the results of observation of the microstructure of the alloy of Example 5 of the invention.

JEM-2100F (FE-TEM) manufactured by JEOL Co. was used for measuring the average particle diameter and the area density of the precipitate. For the FE-TEM observation, two kinds of analysis were performed. First, FE-TEM analysis was performed using the ion milling method, which is a typical specimen production method, and the result is shown in FIG. 4A. As can be seen in FIG. 4A, it was impossible to identify and analyze fine precipitates. Therefore, the FE-TEM analysis of the specimen prepared by the carbon extraction replica method is shown in FIG. 4B for the micro-precipitate which can not be confirmed by the ion milling method.

The results of the measurement according to the above-described characteristic analysis method are shown in Table 2 below.

No. The tensile strength
(MPa) Hardness
(Hv) Electrical conductivity
(% IACS) Softening temperature
(° C) Precipitate average particle diameter
(Nm) Precipitate area density
x 10 ¹⁰ (number / cm 2) Example 2 487 147 84 423 27 1.02 Example 3 493 148 83 419 29 1.04 Example 4 491 148 88 422 31 1.12 Example 5 521 154 87 421 30 1.24 Example 6 548 156 84 417 35 1.27 Example 7 529 153 85 425 33 1.25 Example 8 518 150 82 432 41 1.23 Example 9 527 154 85 423 38 1.28 Example 10 531 154 80 415 36 1.32 Example 11 508 149 81 426 32 1.27 Example 12 519 150 80 420 39 1.31 Example 13 529 152 78 412 41 1.41 Example 14 615 161 79 413 38 1.47 Example 15 629 164 77 410 43 1.54 Example 16 636 167 75 403 41 1.59 Comparative Example 1 445 130 89 451 56 0.012 Comparative Example 2 438 126 90 451 61 0.009 Comparative Example 3 468 132 85 444 99 0.010 Comparative Example 4 498 143 82 433 87 0.011 Comparative Example 5 427 125 90 456 72 0.008 Comparative Example 6 428 125 83 444 83 0.009 Comparative Example 7 437 131 81 425 95 0.010 Comparative Example 8 462 142 79 414 69 0.014 Comparative Example 9 476 143 77 410 103 0.016 Comparative Example 10 480 144 75 407 91 0.018 Comparative Example 11 483 145 73 403 104 0.020 Comparative Example 12 491 146 73 400 78 0.018 Comparative Example 13 503 151 69 399 112 0.022 Comparative Example 14 489 146 73 404 97 0.028 Comparative Example 15 627 169 70 391 121 1.62 Comparative Example 16 632 171 67 382 129 1.69

Comparing Example 4 and Comparative Example 8 in Table 2, Example 4 shows an increase in P content in the component of Comparative Example 8, and by providing P in an amount sufficient for forming fine (FeMn) ₂ P precipitates, As a result, the electric conductivity can be improved.

Also, by confirming the results of Example 5, it can be confirmed that both the strength characteristics and the electrical conductivity characteristics are both excellent.

On the other hand, Comparative Examples 1 to 16 do not satisfy the strength standard, which is one of the characteristics required in the present industry, even if the precipitate control is performed through optimization of the manufacturing process. This is a result of the fact that formation of fine (FeMn) ₂ P precipitates is impossible due to deviation from the optimum component composition of the alloy of the present invention.

Comparative Examples 8 to 13 among the above comparative examples are experiments to confirm whether or not the addition of simple Mn to the existing C19210 alloy is effective. From the results of Comparative Examples 8 to 13, it can be seen that no Mn composition alone satisfies the required characteristics. This is not a simple Mn is added alone (FeMn) ₂ P precipitate formation results Mn is employed is more and results in reducing the electrical conductivity, the end (FeMn) caused by the P content shortage required for the ₂ P precipitate formed in the Cu base to be. In particular, it can be seen that the electric conductivity is drastically reduced although the strength can be improved only by solubility enhancement of the simple addition element.

In summary, the results of the above-described characteristics analysis show that even when the same manufacturing method and analysis method as those of Examples 1 to 16, which can exhibit the characteristics of the alloy of the present invention, are combined, the alloy characteristics of C19210 can not be improved.

For evaluation of the characteristics according to the hot rolling temperature condition, copper alloy specimens according to the composition of Example 1 were prepared by changing the hot rolling temperature condition as shown in Table 3 below, and the properties were evaluated.

Characterization of copper alloy specimens having the composition disclosed in Example 1 according to hot rolling conditions Hot rolling temperature
(° C) The tensile strength
(MPa) Hardness
(Hv) Electrical conductivity
(% IACS) Softening temperature
(° C) Remarks 870 441 131 84 432 Tensile strength and hardness below target physical properties (Fig. 2A) 900 472 145 87 432 All the target properties are met (Fig. 2b) 950 476 146 87 434 Both target properties are met (Figure 2c)

As can be seen in Table 3, when the hot rolling temperature is lower than 900 占 폚, the characteristics of the copper alloy according to the present invention can not be shown. The results of Table 3 are shown in Figs. 2A to 2C. FIG. 2A shows a hot rolled state of a copper alloy for a lead frame at 870.degree. C., which shows that when the structure is observed after hot rolling, the processed structure (rolled structure) remains and affects the post-process. Can be confirmed. In the case of FIGS. 2B and 2C, since the hot rolling temperature is 900 ° C or higher, an isotropic recrystallized structure is formed after hot rolling, thereby realizing the characteristics of the present invention alloy.

Meanwhile, FIG. 3 shows a photograph of the copper alloy specimen produced according to Example 5 observed by FE-SEM in order to confirm the average crystal grain size and microstructure of the copper alloy according to the present invention. According to the photograph shown in Fig. 3, the average crystal grain size in the specimen according to Example 5 was 20 占 퐉 or less and the standard deviation was 5 占 퐉 or less. This result confirms that when the copper alloy according to the present invention is used for electrical and electronic parts and semiconductors, it has a good level of microstructure that can be used without problems of surface defects.

The results of the FE-TEM analysis of the copper alloy specimen of Example 5 are shown in Figs. 4A and 4B.

FIG. 4A is an FE-TEM photograph of a specimen produced through ion milling which is generally used for identification of a precipitate in a copper alloy having the composition described in Example 5. The existence and dispersion of the precipitate is unclear, Analysis is not possible. New analytical methods should be applied to solve these problems.

FIG. 4B is an FE-TEM photograph of a specimen produced by carbon extraction replica method for confirming precipitates in a copper alloy having the composition described in Example 5 to overcome the limitations of the conventional ion milling method. It is possible to accurately analyze the shape, size, composition and surface density of fine precipitates when observing specimens produced by the carbon extraction replica method. Figure 4a the check is possible only about the presence of the precipitate but also look 4b can not be seen in the conventional Cu-Fe-P alloy (FeMn) ₂ P-based precipitates were formed uniformly below the average particle size of the precipitate 50㎚, precipitate (1.0 / ¹⁰ < 10 > / cm < ² >) or more.

Claims (8)

(Fe): 0.09 to 0.20%, P: 0.05 to 0.09%, manganese (Mn): 0.05 to 0.20%, the balance copper (Cu) and 0.05 mass% or less of unavoidable impurities (FeMn) ₂ P precipitate containing at least one species selected from the group consisting of Si, Zn, Ca, Al, Ti, Be, Cr, Co, Ag and Zr, ₂ P precipitate Carbon extraction replica (carbon extraction replica) method is determined with a ratio more than 100,000 times the specimens prepared in a high-resolution transmission electron microscopy (HR-TEM) or a field emission transmission electron microscope (FE-TEM), the (FeMn) ₂ P The precipitate has an average particle diameter of 50 nm or less, a surface density of 1.0 x 10 ¹⁰ / cm ² or more, a tensile strength of 470 MPa or more, a hardness of 145 Hv or more, an electric conductivity of 75% IACS or more, Copper alloy for electronic parts or semiconductors. The method according to claim 1,
And the inevitable impurity content is 0.01 mass% or less. The method according to claim 1,
Ni and Sn in a range of 0.0001 mass% to 0.03 mass%. The method of claim 1,
Wherein the copper alloy has an average crystal grain size of 20 占 퐉 or less and a standard deviation of 5 占 퐉 or less at a crystal grain size measured by a field orientation type scanning electron microscope (FE-SEM) by a crystal orientation analysis method. The method according to claim 1,
The copper alloy is in the form of a sheet or a plate. A method for casting an ingot by dissolving the constituent elements described in any one of claims 1 to 3,
Subjecting the obtained ingot to homogenization heat treatment at 900 ° C to 1000 ° C for 1 to 4 hours and hot rolling at a machining rate of 85 to 95%
A step of cold rolling at a reduction ratio of 87 to 98%
A precipitation heat treatment at a temperature of 430 to 520 DEG C for 1 to 10 hours, and
And subjecting the resultant to complete rolling at a reduction ratio of 10 to 90%. delete delete

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