JP2012057242A - Method of manufacturing copper-based alloy with high strength, high conductivity and high heat resistance, and copper-based alloy with high strength, high conductivity and high heat resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing copper-based alloy with high strength, high conductivity and high heat resistance by improving chemical components and a manufacturing method for the conventional copper alloy for electric/electronic components excellent in plating and stamping properties.SOLUTION: Ingot of the copper-based alloy containing predetermined components is heated to a temperature of 800-1050°C, and hot-rolled with a draft of 50% or more. Then, the ingot is cold-rolled with a draft of 30% or more, held at a temperature of 950-1050°C for a minute or more, cooled down to 300°C within 30 seconds, and cold-rolled with a draft of 30% or more. Then, aging annealing therefor is performed for 1-4 hours at a temperature of 550-625°C, and for another 1-10 hours at a temperature of 400-500°C. After cold-rolling with a draft of 70-90%, distortion removing annealing is performed for 1-5 minutes at a temperature of 300-450°C.

Description

  The present invention relates to a method for producing a high-strength, high-conductivity, high-heat-resistant copper-based alloy suitable for electrical and electronic component materials typified by lead frames for multi-pin ICs, etc. It is about.

  Copper and copper-based alloys have been used as materials for electrical and electronic parts such as lead frames because of their very high electrical conductivity and thermal conductivity. In recent years, lead frames have become thinner, narrow pins, and narrow pitches, and some of the lead frames have a thickness of 100 μm or less, and a very high strength is required.

  In the production of a lead frame, a strip material obtained by rolling copper and a copper base alloy to a predetermined thickness is subjected to stamping or etching to be processed into a predetermined shape. In the stamping process, high-temperature heat treatment is often performed such as heating at a temperature of 400 ° C. or higher in a strain removing process for removing strain due to stamping. Furthermore, various plating processes, die bonding, wire bonding, and resin molding are performed in the packaging process.

  Therefore, the lead frame material has not only conductivity and strength (primary characteristics) but also stamping properties, heat resistance (degree of strength decrease when heated to high temperature), etching property, various plating properties, and solder adhesion. In addition, oxide film adhesion, resin adhesion, wire bonding properties, etc. (secondary characteristics) are required.

  There is no material that sufficiently satisfies all of these characteristics. However, as a lead frame material for a multi-pin IC, Cu-2.2 mass% Fe-0.03 mass% P-0. CDA Alloy 194 having a standard chemical composition of 12 mass% Zn (see, for example, Patent Document 1), CDA Alloy 7025 having a standard chemical composition of Cu-3.0 mass% Ni-0.65 mass% Si-0.15 mass% Mg, In addition, CDA Alloy 18045 having a standard chemical composition of Cu-0.23 mass% Cr-0.25 mass% Sn-0.20 mass% Zn is being consolidated (CDA: American Copper Development Association).

CDA Alloy 194 has a tensile strength of about 550 N / mm ² and a Vickers hardness of about 160 Hv as ESH, which is the highest strength grade, and is lower in strength than the other two types of copper-based alloys. Moreover, heat resistance is also low, for example, if it heats at 450 degreeC for about 5 minutes, it will soften to 80% or less of the original strength. On the other hand, it is widely used because it has no serious defects in secondary characteristics and is easily available.

  As a method for improving the strength and heat resistance of a copper-based alloy, a method by adding a trace amount of an impurity element (alloy element) such as Mg (for example, see Patent Document 2) or a method by improving a manufacturing method (for example, Patent Document 3). See).

Japanese Patent Publication No. 45-010623 Japanese Patent Publication No. 64-000449 Japanese Patent No. 3763234

  However, for example, Mg is significantly improved in strength and heat resistance even when added in an amount of about 0.05 mass% (method disclosed in Patent Document 2), but on the other hand, it promotes abnormal precipitation at the time of plating. Addition is undesirable because it degrades properties other than strength and heat resistance. Moreover, the copper base alloy manufactured by the improvement of the conventional manufacturing method (method disclosed by patent document 3) is inferior to CDA Alloy 18045 in the intensity | strength and heat resistance, and the further improvement is calculated | required.

  The present invention has been made to solve the above-mentioned problems, and has improved the chemical composition and manufacturing method of conventional copper-based alloys for electric and electronic parts, which are excellent in plating properties and stamping properties, and has high strength, high conductivity and high heat resistance. It aims at obtaining the manufacturing method of a heat resistant copper base alloy, and a high strength high electrical conductivity high heat resistant copper base alloy.

  In order to achieve the above object, the first aspect of the present invention includes Fe: 1.8 to 2.5 mass%, P: 0.01 to 0.1 mass%, Zn: 0.01 to 1.5 mass%, Sn. : 0.01-0.2 mass%, and elements containing Mg, Al, Si, Ti, Cr, Mn, Co, Ni in a total amount of 0.001-0.05 mass%, with the balance being Cu and inevitable impurities The copper base alloy ingot is heated to a temperature of 800 to 1050 ° C. and hot-rolled with a reduction rate of 50% or more, and then cold-rolled with a reduction rate of 30% or more, and a temperature of 950 to 1050 ° C. For 1 minute or longer, and then cooled to 300 ° C. for 30 seconds or less, then cold-rolled at a reduction rate of 30% or more, then at a temperature of 550 to 625 ° C. for 1 to 4 hours, and further 400 to 500 ° C. Aging at temperature for 1-10 hours, then rolling reduction After rolling 0% to 90% of the cold, a method of producing a high strength and high electrical conductivity high heat resistance copper-based alloy performs distortion removal annealing 1-5 minutes at a temperature of 300 to 450 ° C..

The second aspect of the present invention is a high-strength, high-conductivity, high-heat-resistant copper-based alloy produced by the above method, having a conductivity of 65% IACS or more, a tensile strength of 560 N / mm ² or more, and a Vickers hardness. This is a high-strength, high-conductivity, high-heat-resistant copper-based alloy having a thickness of 165 Hv or more and having a strength after heating at 500 ° C. for 5 minutes of 90% or more before heating.

  According to the present invention, by improving the chemical composition and manufacturing method of a conventional copper-based alloy for electric and electronic parts having excellent plating properties and stamping properties, a method for manufacturing a high-strength, high-conductivity, high-heat-resistant copper-based alloy and The copper base alloy can be provided.

  Hereinafter, a preferred embodiment of the present invention will be described.

  First, the chemical composition of the high-strength, high-conductivity, high-heat-resistant copper-based alloy according to the present invention will be described.

  The copper-based alloy according to the present invention contains Fe, P, Zn, and Sn as main alloy elements, and further contains a trace amount of elements composed of Mg, Al, Si, Ti, Cr, Mn, Co, and Ni, and the balance. Consists of Cu and inevitable impurities.

  Fe contributes to improvement in strength and heat resistance. If the amount added is less than 1.8 mass%, the amount of Fe deposited is insufficient, and the required strength and heat resistance cannot be obtained. Moreover, hot rolling workability falls remarkably. On the other hand, if it exceeds 2.5 mass%, the generation of coarse crystals of Fe during casting and the occurrence of undissolved Fe during dissolution occur, and these remain in the final product, resulting in discoloration, etching properties, It causes a decrease in plating performance, bonding failure, cracking during bending, and the like. Also, the decrease in conductivity is increased. Therefore, the addition amount of Fe is 1.8 to 2.5 mass%, preferably 2.1 to 2.3 mass%.

  In addition to contributing as a deoxidizer, P forms a compound with Fe and contributes to improvement in strength. If the amount added is less than 0.01 mass%, a sufficient effect cannot be obtained. On the other hand, if it exceeds 0.1 mass%, the castability and hot workability are lowered and the conductivity is also lowered. Therefore, the addition amount of P is 0.01 to 0.1 mass%, preferably 0.02 to 0.04 mass%.

  Zn contributes to the improvement of solder adhesion and solder heat-resistant peelability necessary for electric and electronic parts, and also contributes as a deoxidizer. If the amount added is less than 0.01 mass%, a sufficient effect cannot be obtained. On the other hand, if it exceeds 1.5 mass%, the conductivity is lowered. Therefore, the addition amount of Zn is 0.01 to 1.5 mass%, preferably 0.1 to 0.2 mass%.

  Sn dissolves in Cu and contributes to improvement in strength and heat resistance. If the amount added is less than 0.01 mass%, a sufficient effect cannot be obtained. On the other hand, when it exceeds 0.2 mass%, the decrease in the conductivity becomes remarkable, and the castability deteriorates remarkably. Therefore, the amount of Sn added is 0.01 to 0.2 mass%, preferably 0.05 to 0.10 mass%.

  Furthermore, even if the total amount of elements composed of Mg, Al, Si, Ti, Cr, Mn, Co, and Ni is contained in an amount of 0.001 to 0.05 mass%, the characteristics are satisfied, but if it exceeds 0.05 mass% Insufficient conductivity and decrease in plating properties.

  By setting it as the above chemical compositions, the copper base alloy which has favorable secondary characteristics, such as plating property and stamping property, can be provided.

  Next, the manufacturing method of the high intensity | strength high electrical conductivity high heat resistant copper base alloy based on this invention is demonstrated.

  Usually, after adjusting and melting | dissolving to the said chemical composition with electric furnaces, such as a crucible type melting furnace and a channel type melting furnace, the rectangular cross-section ingot of thickness 150-250mm and width 400-1000mm is manufactured by continuous casting, for example.

  Next, the ingot is heated to a temperature of 800 to 1050 ° C. and hot-rolled at a reduction rate of 50% or more.

  Fe or Fe-P compounds precipitated in the cooling process during casting by heating are re-dissolved in Cu. However, if the heating temperature is lower than 800 ° C., it does not sufficiently dissolve and recrystallization does not occur sufficiently. Hot workability decreases and cracks occur. On the other hand, when the heating temperature is higher than 1050 ° C., the oxide scale increases and the crystal becomes coarse. Desirably, it is 900-980 degreeC.

  Further, if the rolling reduction is lower than 50%, recrystallization does not occur uniformly, and a non-uniform metal structure may remain in the final product. Desirably, it is 90% or more.

  The cooling rate after hot rolling is not particularly defined in the present invention, and can be cooled after completion of hot rolling by a general water-cooled shower or the like.

  Thereafter, the oxide scale is removed and cold rolling is performed, but the reduction ratio is desirably 30% or more. When the rolling reduction is lower than 30%, a uniform recrystallized structure cannot be obtained in the subsequent solution treatment.

  Subsequently, after heating to a temperature of 950 to 1050 ° C. and holding for 1 minute or longer, it is cooled to 300 ° C. in a time of 30 seconds or shorter. Hereinafter, this operation is referred to as a solution treatment.

  In the present invention, the conditions of the solution treatment are the most important. By quenching from a high temperature, Fe atoms are solid-solved in a supersaturated state, and many atomic vacancies called quenching clusters are introduced. Features. Quenched clusters have a great influence on the subsequent aging precipitation behavior.

  If the heating temperature of the solution treatment is lower than 950 ° C., the target strength and heat resistance cannot be obtained, while if it exceeds 1050 ° C., coarsening of recrystallized grains becomes remarkable. Moreover, even if the heating holding time is shorter than 1 minute, the target strength and heat resistance cannot be obtained. The cooling rate after heating must be as fast as possible so that Fe does not precipitate during cooling, and it takes 30 seconds or less from the start of cooling to 300 ° C. at which the diffusion rate of Fe is sufficiently slow. Must be allowed to cool.

  Next, after cold rolling at a rolling reduction of 30% or more, the temperature is 550 to 625 ° C. for 1 to 4 hours (hereinafter referred to as aging 1), and further at the temperature of 400 to 500 ° C. for 1 to 10 hours (hereinafter referred to as aging 2). Heat to precipitate Fe and Fe-P compounds in the parent phase of Cu. Hereinafter, this operation is called aging annealing. When the temperature of aging 1 is lower than 550 ° C., the precipitate does not sufficiently grow to a size that contributes to improvement in strength and heat resistance (insufficient aging), while when it is higher than 625 ° C., the precipitate becomes coarse (over-aging). ), Strength and heat resistance are reduced. Desirably, it is 575-600 degreeC. Further, if the time of aging 1 is shorter than 1 hour, aging is insufficient, and if it is longer than 4 hours, it is over-ageed and the strength and heat resistance are lowered. Desirably 2 to 3 hours.

  Aging 2 is a heat treatment for precipitating a large amount of fine precipitates at a temperature lower than that of aging 1, and is a heat treatment for improving the conductivity rather than the strength and heat resistance. If the temperature of aging 2 is lower than 400 ° C., the deposition rate is remarkably reduced and the conductivity is not sufficiently improved, and if it is higher than 500 ° C., it is over-aged and the strength and heat resistance may be lowered. Desirably, it is 425-475 degreeC. Further, when the time of aging 2 is shorter than 1 hour, the conductivity is not sufficiently improved, and when it is longer than 10 hours, it is over-ageed and the strength and heat resistance may be lowered. Desirably 4 to 6 hours. In addition, aging 2 may be started during the cooling of aging 1 or may be started after being lowered to room temperature. Furthermore, between the aging 1 and the aging 2, cold rolling with a reduction rate of 50% or less may be added.

  After aging annealing, cold rolling with a rolling reduction of 70 to 90% is performed. Here, the strength is improved by work hardening. Therefore, if the rolling reduction is lower than 70%, sufficient strength cannot be obtained, and if it is higher than 90%, the improvement in strength is saturated and the heat resistance is significantly reduced. Desirably, it is 75 to 85%.

  Finally, strain removal annealing is performed by holding at a temperature of 300 to 450 ° C. for 1 to 5 minutes. The aim here is to recover growth. If the temperature is lower than 300 ° C. or the time is shorter than 1 minute, the elongation is not sufficiently recovered, and if the temperature is higher than 450 ° C. or the time is longer than 5 minutes, the strength is lowered.

As described above, the production method according to the present invention controls the metal structure of the Cu matrix and the aging precipitation behavior of the precipitate, and has a conductivity of 65% IACS or more and a tensile strength of 560 N / mm ² or more. A copper-based alloy having excellent characteristics such as Vickers hardness of 165 Hv or more can be produced.

  Moreover, the strength after heating at a high temperature of 500 ° C. for 5 minutes is 90% or more of the strength before heating, and a copper-based alloy having excellent heat resistance can be provided.

  In addition, the manufacturing method of the high intensity | strength high electrical conductivity high heat resistant copper base alloy which concerns on this invention is not restricted to the said embodiment, For example, the copper base alloy (Cu-Fe- containing a different alloy element as a main component) The present invention is also applicable to Ni-P-based alloys, etc., and providing a copper-based alloy having further improved strength, conductivity, and heat resistance in a well-balanced manner by appropriately changing the rolling reduction and solution treatment temperature. it can.

  Examples of the present invention will be described below.

  A copper base alloy having a chemical composition of Fe: 2.2 mass%, P: 0.03 mass%, Zn: 0.12 mass%, Sn: 0.05 mass%, Si: 0.01 mass% in a medium frequency induction heating type crucible furnace. After dissolution adjustment, semi-continuous casting was performed with a copper mold to cast a rectangular cross-section ingot having a cross-sectional size of 180 mm in thickness and 500 mm in width.

  It heated to 950 degreeC with the temperature increase rate of 300 degreeC / h with the heating furnace, and it hold | maintained for 30 minutes, and it hot-rolled after that, and was 12 mm in thickness (rolling rate: about 93%). After the final pass, it was cooled from a temperature of about 700 ° C. to 100 ° C. or less at a cooling rate of 200 ° C./min with a water-cooled shower. After removing the oxide scale on the surface, it was cold-rolled to a thickness of 2 mm (reduction rate: about 83%).

  Next, the coil was cut into several pieces in the longitudinal direction. These coils were first subjected to a solution treatment under various conditions in a continuous annealing furnace, and then cold-rolled to a thickness of 0.75 mm (reduction rate: about 62%). Next, after performing aging annealing under various conditions in a batch type annealing furnace, it was cold-rolled to a thickness of 0.15 mm (reduction rate: about 80%). Finally, distortion removal annealing corresponding to 400 ° C. × 2 minutes was performed in a continuous annealing furnace.

  Conductivity measurements, cross-section Vickers hardness measurements, and tensile tests (measurement of tensile strength and breaking elongation) were performed on the various copper-based alloys produced. In addition, in order to evaluate the heat resistance of the copper-based alloy, the copper-based alloy was immersed in a salt bath maintained at 500 ° C. for 5 minutes, then placed in a water bath and rapidly cooled, and the Vickers hardness of the cross section was measured. The ratio of the measured Vickers hardness after heating to the Vickers hardness before heating was determined, and the percentage expressed as a percentage was defined as heat resistance.

  Table 1 shows the relationship between the manufacturing conditions of the copper-based alloy and the respective characteristics.

As shown in Table 1, in the copper base alloys A and B according to the present invention, both the electrical conductivity is 65% IACS or more, the tensile strength is 560 N / mm ² or more, the Vickers hardness is 165 Hv or more, and the heat resistance is 90% or more. Has characteristics. Further, when A and B are compared, A having a higher heating temperature in the solution treatment and higher Aging 1 temperature has higher strength and heat resistance. On the other hand, the copper base alloys C, D and E manufactured by the conventional method have a lower solution treatment temperature and / or a lower cooling rate than the present invention (copper base alloys A and B), and have a high strength and heat resistance. It became lower than the copper base alloys A and B according to the present invention. In other words, in order to increase the strength, electrical conductivity, and heat resistance of a copper-based alloy, the solution treatment temperature is set to a high temperature, and many quenching clusters are introduced, and the cooling rate during the solution treatment is increased as much as possible. It can be seen that it is important to prevent the elements from precipitating.

  Furthermore, the copper base alloy F of the comparative example is not solution treated, G has a solution temperature of less than 900 ° C., both of which are lower in strength and heat resistance than the copper base alloys A and B of the present invention, The hardness is significantly reduced to less than 160 Hv and the heat resistance is less than 75%.

Comparative examples of copper-based alloys H, I, J, and K having different aging 1 conditions from the present invention have low strength and heat resistance due to insufficient aging or overaging, and have a hardness of 155 Hv or less and a tensile strength of 520 N. / Mm ² and heat resistance is less than 90%.

In the copper base alloys L, M, N, and O of comparative examples in which the condition of aging 2 is different from that of the present invention, L and N have high strength and heat resistance, but the conductivity is less than 60% IACS due to insufficient aging. Low. M and O have high conductivity, but due to overaging, the hardness is less than 160 Hv, the tensile strength is less than 540 N / mm ² , and the heat resistance is less than 90%.

Claims (2)

  Fe: 1.8-2.5 mass%, P: 0.01-0.1 mass%, Zn: 0.01-1.5 mass%, Sn: 0.01-0.2 mass%, and Mg, Al, Si , Ti, Cr, Mn, Co, Ni elements in a total amount of 0.001 to 0.05 mass%, the remainder of the copper-based alloy ingot consisting of Cu and unavoidable impurities at a temperature of 800-1050 ℃ After heating and hot rolling at a reduction rate of 50% or more, cold rolling at a reduction rate of 30% or more, holding at a temperature of 950 to 1050 ° C for 1 minute or longer, and then to 300 ° C for 30 seconds or less After cooling and then cold rolling at a reduction rate of 30% or more, aging annealing is performed at a temperature of 550 to 625 ° C. for 1 to 4 hours, and further at a temperature of 400 to 500 ° C. for 1 to 10 hours, and then a reduction rate of 70 After 90% cold rolling, the temperature is 300-450 ° C Method of producing a high strength and high electrical conductivity high heat resistance copper-based alloy and performing distortion removal annealing of 1-5 minutes in. A high-strength, high-conductivity, high-heat-resistant copper-based alloy manufactured by the method according to claim 1, having an electrical conductivity of 65% IACS or higher, a tensile strength of 560 N / mm ² or higher, and a Vickers hardness of 165 Hv or higher. The strength after heating at 500 ° C. for 5 minutes is 90% or more before heating, and is a high strength, high conductivity, high heat resistance copper-based alloy.