KR101682801B1 - Fe-P BASED COPPER ALLOY SHEET EXCELLENT IN STRENGTH, HEAT RESISTANCE AND BENDING WORKABILITY - Google Patents

Abstract

A Fe-P based copper alloy plate having high strength and excellent in heat resistance and adhesion to an oxide film is provided.
At least one of Sn and Mg in an amount of 0.1 to 0.5 mass%, C in an amount of 0.003 mass% or less, Co, Si, and Cr in an amount of 0.1 to 5 mass%, Fe in an amount of 1.6 to 2.6 mass%, P in an amount of 0.01 to 0.15 mass%, Zn in an amount of 0.01 to 1.0 mass% Of the total grain size is 0.05% by mass or less, the balance Cu and inevitable impurities, and the crystal structure parallel to the rolling direction and perpendicular to the plate surface is observed by EBSD, the average is 10μm or less, and having a conductivity of 50% IACS or more, Vickers hardness of 180Hv or more, the equivalent circle diameter of 10~40nm of Fe or Fe-P precipitated particles, the presence density of 20 / μm ² or more of the compounds.

Description

(Fe-P BASED COPPER ALLOY SHEET EXCELLENT IN STRENGTH, HEAT RESISTANCE AND BENDING WORKABILITY) which is excellent in strength, heat resistance and bending workability,

The present invention relates to an Fe-P-based copper alloy plate which is excellent in strength, heat resistance and bending workability and is suitable as a material for electric and electronic parts such as semiconductor lead frames, terminals, connectors and bus bars.

Copper and copper (base) alloys have been used as materials for electrical and electronic parts including lead frames because of their high conductivity and thermal conductivity. In recent years, thinner, narrower and finer pitches of lead frames have progressed gradually, and some of them have thicknesses of 100 μm or less, and very high strength is required.

Further, in the production of the lead frame, stamping or etching treatment is applied to a raw material obtained by rolling a copper and a copper-based alloy to a predetermined thickness, thereby processing the lead frame into a predetermined shape. In the stamping process, a high temperature heat treatment is often performed in a deformation removing process for removing deformation caused by stamping, such as heating at a temperature of 400 DEG C or higher. In addition, die bonding, wire bonding, and resin molding are performed in various plating processes and packaging processes.

Therefore, the lead frame material is required to have not only the electric conductivity and the strength (primary characteristics) but also the stamping property, the heat resistance (degree of strength reduction when heated at a high temperature), the etching property, various plating properties, Adhesion, wire / bonding properties (secondary properties) are required.

As a lead frame material for a multi-pin IC, Cu-2.2 mass% Fe-0.03 mass% P-0.12 mass% Zn is used as the lead frame material from the standpoints of characteristics, cost and availability. CDA Alloy 704 having a standard chemical composition, CDA Alloy 194 having a standard chemical composition, Cu-3.0 mass% Ni-0.65 mass% Si-0.15 mass% Mg, CDA Alloy 7025 having a standard chemical composition and Cu-0.23 mass% Cr-0.25 mass% Sn- % Zn as the standard chemical composition. CDA, on the other hand, refers to the American Copper Development Association.

Here, CDA Alloy 7025 (Vickers hardness of 200 Hv), which has the highest strength, is used as a lead frame material of a sapphire IC that needs strength in particular. However, since the present material contains a large amount of Ni and Si which deteriorate the adhesion of the oxide film, there is a drawback that the adhesion of the oxide film is low.

In a semiconductor device, a package for sealing a semiconductor chip with a thermosetting resin becomes mainstream in terms of economy, and it is important to maintain the reliability of the package. The reliability of the package depends on the adhesion between the mold resin and the lead frame. When the oxide film having low adhesiveness is formed on the surface of the lead frame due to the thermal history during the assembly process of the semiconductor device, the adhesion between the mold resin and the lead frame deteriorates, and cracks or peeling of the package occur as heat at the time of mounting on the printed board, Reliability is lowered.

Therefore, in order to secure the reliability of the package, it is important that the oxide film in the lead frame material has high adhesion, but CDA Alloy 7025 has low characteristics. In addition, CDA Alloy 7025 has a problem that a smut occurs in an etching process or the like and the adhesion of the plating is deteriorated, and it is also expensive and therefore difficult to use.

On the other hand, the Fe-P-based CDA Alloy 194 has a low tensile strength of about 550 N / mm ² and a Vickers hardness of about 160 Hv even with ESH of the highest strength (quality). Further, the heat resistance is also relatively low. For example, heating at 450 占 폚 for about 5 minutes results in softening to 80% or less of the original strength. However, CDA Alloy 194 has been widely used because it has no significant defects in secondary characteristics such as stamping properties, is excellent in adhesion of an oxide film, is inexpensive, and has good availability.

Patent Document 1 discloses that Fe-P type copper alloy is strengthened by adding Mg and Sn to the Fe-P type copper alloy. Further, Patent Document 2 discloses an Fe-P type copper alloy plate improved in stamping property (punching workability and bending workability) by sizing a crystal structure. Patent Literature 3 discloses a method of producing Fe-P based alloy by taking a specific manufacturing method such as hot rolling and cold rolling an Fe-P type copper alloy, and then performing a solution treatment of heating to 950 to 1050 캜 and then quenching to 300 캜 or lower. P-based copper alloy sheet is improved in strength and heat resistance.

Japanese Unexamined Patent Application Publication No. 4-41631 Japanese Patent Application Laid-Open No. 2000-104131 Japanese Patent Laid-Open Publication No. 2012-57242

However, the Fe-P based copper alloy sheet of Patent Document 1 has high strength, but it can not be said that the heat resistance is sufficient, and the stamping property is not studied. The Fe-P based copper alloy sheet of Patent Document 2 is excellent in stamping property, but is not necessarily excellent in heat resistance. The Fe-P based copper alloy sheet of Patent Document 3 is excellent in strength and heat resistance, but the stamping property is not studied.

The present invention provides an Fe-P type copper alloy plate which is made in view of the present state of Fe-P type copper alloy plate and which has high strength, high heat resistance and excellent stampability (particularly bending workability) .

The Fe-P-based copper alloy sheet according to the present invention is a Fe-P-based copper alloy plate comprising 1.6 to 2.6 mass% of P, 0.01 to 0.15 mass% of P, 0.01 to 1.0 mass% of Zn, 0.1 to 0.5 mass% , C: not more than 0.003 mass%, Co, Si and Cr in a total amount of not more than 0.05 mass%, the balance being Cu and unavoidable impurities, and a crystal structure parallel to the rolling direction and perpendicular to the plate surface is observed with EBSD , A precipitate of Fe or Fe-P compound having a weighted average weighted average diameter of each crystal grain of 10 μm or less, a conductivity of 50% IACS or more, a Vickers hardness of 180 Hv or more, and a circle equivalent diameter of 10 to 40 nm And has an existence density of 20 / μm ² or more. In the present invention, the term " copper alloy plate " is used to mean a copper alloy plate.

According to the present invention, it is possible to provide an Fe-P type copper alloy plate having strength close to that of CDA Alloy 7025 and excellent in strength, heat resistance and adhesion of an oxide film.

Fig. 20, 21, and 23, respectively.

Hereinafter, the Fe-P based copper alloy sheet according to the present invention will be described in more detail.

(Chemical composition of Fe-P type copper alloy)

Fe contributes to improvement of the strength and heat resistance of the Fe-P-based copper alloy sheet and also has an effect of suppressing the growth of crystal grains during hot rolling or in a recrystallization heat treatment. If the content of Fe is less than 1.6 mass%, the above effect becomes insufficient. On the other hand, when the content of Fe exceeds 2.6 mass%, coarse Fe particles (several μm or more in diameter) are produced by two-liquid phase separation or crystallization during melting and casting, The property is deteriorated. Therefore, the content of Fe is preferably 1.6 to 2.6 mass%, the lower limit is preferably 1.7 mass%, more preferably 1.8 mass%, and the upper limit is preferably 2.5 mass%, more preferably 2.4 mass% do.

P not only contributes as a deoxidizing agent but also forms precipitation particles of an Fe-P compound to improve the strength and heat resistance of the Fe-P-based copper alloy plate. P has an effect of suppressing grain growth during hot rolling or during recrystallization heat treatment. If the content of P is less than 0.01% by mass, the above effects are insufficient. On the other hand, when the P content exceeds 0.15 mass%, the conductivity is lowered and the adhesion of the oxide film is lowered. Therefore, the content of P is set to 0.01 to 0.15 mass%, the lower limit is preferably 0.015 mass%, more preferably 0.02 mass%, and the upper limit is preferably 0.13 mass%, more preferably 0.10 mass% do.

Zn improves the solder heat-releasability of the Fe-P-based copper alloy sheet and the adhesion of the oxide film. If the content of Zn is less than 0.01 mass%, the effect is not sufficient, while if it exceeds 1.0 mass%, the conductivity is deteriorated. Therefore, the Zn content is preferably 0.01 to 1.0% by mass, the lower limit is preferably 0.02% by mass, more preferably 0.05% by mass, and the upper limit is preferably 0.8% by mass, more preferably 0.5% do.

Sn and Mg have an effect of improving the strength and heat resistance of the Fe-P based copper alloy sheet dissolved in the base material, and at least one of Sn and Mg (one or both of Sn and Mg) is added. If the content of at least one of Sn and Mg is less than 0.2 mass%, the above-mentioned effect is not sufficient and the Vickers hardness of 180 Hv or more can not be satisfied. On the other hand, when the content of at least one of Sn and Mg exceeds 0.5% by mass, the conductivity is lowered and the adhesion of the oxide film is lowered. Therefore, the content of at least one of Sn and Mg is set to 0.2 to 0.5 mass%, the lower limit is preferably 0.25 mass%, more preferably 0.3 mass%, and the upper limit is preferably 0.45 mass% Is set to 0.40 mass%.

If the content of C as the unavoidable impurity exceeds 0.003 mass% or the total content of Co, Si and Cr as the unavoidable impurities equals to more than 0.05 mass% in the Fe-P type copper alloy, Coarse Fe particles are easily formed by crystallization. As a result, the strength and heat resistance of the Fe-P based copper alloy are lowered, and the plating property and the etching property are lowered. Therefore, the C content is set to 0.003 mass% or less, and the total content of Co, Si and Cr is set to 0.05 mass% or less. On the other hand, C may be mixed in excess of the limit from charcoal or graphite particles scattered for the purpose of preventing oxidation on the surface of the molten metal during melting and casting, graphite mold and the like. In such a case, in order to reduce the C content, it is possible to reduce the contact area with the molten metal by using an Fe raw material having a low C content, reducing the amount of scattered charcoal or graphite particles, or increasing the size of charcoal or graphite particles , And a means for changing the mold can be used.

(Average crystal grain size)

The crystal structure of a cross section parallel to the rolling direction of the Fe-P type copper alloy sheet and perpendicular to the plate surface was observed with EBSD (Electron Back Scatter Diffraction) (grain boundary condition: orientation difference of 5 degrees or more) The diameter was calculated, and the circle equivalent diameter of each crystal grain was weighted by area to obtain a weighted average. In the present invention, this was regarded as an average crystal grain size. This weighted average is taken as an average crystal grain size because when a coarse grain and a fine grain are mixed together as in an Fe-P type copper alloy plate, simply taking an additive average results in a smaller grain size than actual conditions to be. If the average crystal grain size exceeds 10 탆, the bending workability and punch workability are lowered, and the strength and heat resistance are also lowered. Therefore, the average crystal grain size is 10 μm or less, preferably 8 μm or less, and more preferably 6 μm or less. The smaller the average crystal grain size, the better, and the lower limit value does not need to be specially defined, but it can be reduced to about 3 탆 by a manufacturing method described later.

(Presence density of precipitated particles)

Precipitated particles having a circle-equivalent diameter of 10 to 40 nm among the precipitated particles of Fe or Fe-P compound fix the potential to improve the strength and heat resistance of the Fe-P based copper alloy plate. However, if the presence density of the precipitated particles is less than 20 particles / μm ² , the precipitation of particles that can be pinned is small and the improvement in strength and heat resistance is insufficient. Therefore, the existing density of precipitated particles of Fe or Fe-P compound having a circle equivalent diameter of 10 to 40 nm is not less than 20 particles / μm ² , preferably not less than 25 particles / μm ² , more preferably not less than 30 particles / μm ² . May exist density is higher, the upper limit need not specifically determined, it is within the composition range of the present invention it is possible to increase the density up to about 40 / μm ² by the method to be described later.

(Production method of Fe-P type copper alloy plate)

The production method of the present invention is as follows.

First, an ingot is prepared by dissolving a raw material by using a usual crucible-type melting furnace or the like and pouring a molten metal into an ordinary mold or a carbon mold after the composition is adjusted.

Next, the ingot is heated to a temperature of 850 to 1050 占 폚 to perform hot rolling at a rolling processing rate of 50% or more, and the end temperature of hot rolling is set to 750 占 폚 or more. The cooling after the hot rolling is rapidly cooled by a water cooling or the like at a cooling rate of at least 10 캜 / second from the hot rolling end temperature (= cooling start temperature) to at least 300 캜.

If the heating temperature of the hot rolling is less than 850 DEG C, Fe and Fe-P compounds are precipitated and coarsened, so that Fe and P are consumed as much, and the fine Fe and Fe-P compounds precipitated by the precipitation heat treatment are reduced, The strength and heat resistance are lowered. On the other hand, if it exceeds 1050 占 폚, it becomes close to the melting point, so hot cracking occurs. Further, the oxidation becomes vigorous, the oxide is dried by hot rolling, and the product plate is left as a defect in some cases. Therefore, the heating temperature of the hot rolling is 850 to 1050 캜, preferably 870 to 1030 캜, more preferably 890 to 1010 캜.

If the rolling rate of the hot rolling is less than 50%, recrystallization does not occur and the cast structure may remain. Therefore, the rolling rate of the hot rolling is set to 50% or more, preferably 60% or more, more preferably 70% or more.

When the end temperature of the hot rolling is less than 750 캜, the precipitation amount of Fe or Fe-P compound is increased and coarsened, so that fine Fe and Fe-P compounds precipitated in the precipitation heat treatment are decreased, Heat resistance is lowered. In addition, when the end temperature of the hot rolling is less than 750 캜, the average crystal grain size of the product plate becomes large. This is considered to be because the coarsened Fe or Fe-P compound becomes a starting point of recrystallization at the time of the recrystallization heat treatment and promotes recrystallization. Therefore, the termination temperature of the hot rolling is set to 750 ° C or higher, preferably 770 ° C or higher, more preferably 790 ° C or higher.

If the cooling rate after hot rolling becomes less than 10 ° C / sec in the range from the hot rolling end temperature to 300 ° C, Fe and Fe-P compounds precipitate and coarse even during cooling. Therefore, the fine Fe Or the Fe-P compound decreases, and the strength and heat resistance of the product plate are lowered. Therefore, the cooling rate after hot rolling is at least 10 ° C / second, preferably at least 20 ° C / second, more preferably at least 30 ° C / second. After the hot rolled material is cooled and reaches 300 캜, it is not necessary to quench it.

Then, the oxide scale of the hot rolled material is removed, and cold rolling is performed. The rolling rate of the cold rolling is set to 50% or more, preferably 60% or more, more preferably 70% or more, in order to obtain a uniform recrystallized structure in a subsequent recrystallization heat treatment.

The recrystallization heat treatment is a heat treatment for forming fine recrystallized grains and is maintained at a heating temperature of about 550 to 900 DEG C for about 1 second to 10 minutes. If the heating temperature is lower than 550 캜, it is difficult to recrystallize. When the heating temperature exceeds 900 캜, recrystallized grains become coarse. Therefore, the heating temperature is 550 to 900 占 폚, preferably 570 to 880 占 폚, and more preferably 590 to 860 占 폚 or so. The holding time may be appropriately selected depending on the heating temperature, but it is set to a short time of about 1 second to 10 minutes. If the holding time is less than 1 second, it is difficult to be re-determined. When the holding time exceeds 10 minutes, the recrystallized grains are coarsened and the average crystal grain size of the product plate becomes large. In addition, since the precipitation amount of Fe or Fe-P compound is increased and coarsened, fine Fe and Fe-P compounds precipitated in the subsequent precipitation heat treatment decrease. Therefore, the holding time is 1 second to 10 minutes, preferably 2 seconds to 5 minutes, and more preferably 5 seconds to 2 minutes.

The heating rate of the recrystallization heat treatment is set to 1 deg. C / sec or more in the range of 300 deg. If the heating rate is less than 1 占 폚 / sec, precipitation of Fe or Fe-P compound occurs during heating, and fine recrystallized grains can not be obtained. This is considered to be because the Fe or Fe-P compound precipitated during heating is coarsened with the rise in temperature, which becomes a starting point of recrystallization and promotes recrystallization. In addition, precipitation of Fe or Fe-P compounds occurs during heating and coarsening, so that fine Fe and Fe-P compounds precipitated in precipitation heat treatment are reduced. Therefore, the heating rate of the recrystallization heat treatment is set to 1 占 폚 / sec or more, preferably 2 占 폚 / sec or more, more preferably 5 占 폚 / sec or more.

The cooling rate after the recrystallization heat treatment is set at 5 ° C / second or higher in the range from the heating temperature to 300 ° C. If the cooling rate in this temperature range is less than 5 占 폚 / sec, precipitation of Fe or Fe-P compound occurs during cooling and coarsening, so that fine Fe and Fe-P compounds precipitated in the precipitation heat treatment decrease. Therefore, the cooling rate after the recrystallization heat treatment is 5 ° C / second or more, preferably 10 ° C / second or more, and more preferably 20 ° C / second or more.

After the recrystallization heat treatment, precipitation heat treatment is performed with or without cold rolling. The precipitation heat treatment is a heat treatment for producing a large number of fine precipitates of Fe or Fe-P compound (having a circle-equivalent diameter of 10 to 40 nm), and a precipitate is produced even if cold rolling is not carried out. However, So that it is possible to increase the strength more effectively.

The precipitation heat treatment is carried out at a heating temperature of about 300 to 600 ° C. for about 0.5 to 30 hours. If the heating temperature is less than 300 ° C, the precipitation amount is small. If the heating temperature is more than 600 ° C, the precipitate is liable to be coarsened. Therefore, the heating temperature is set to 300 to 600 占 폚, preferably 320 to 580 占 폚, and more preferably 340 to 560 占 폚. The holding time may be appropriately selected depending on the heating temperature, but is set to a time of about 0.5 to 30 hours. If the holding time is less than 0.5 hour, the precipitation tends to become insufficient, while if it exceeds 30 hours, the influence on the productivity deterioration becomes large. Therefore, the holding time is 0.5 to 30 hours, preferably 1 to 25 hours, more preferably 1.5 to 20 hours.

On the other hand, in order to further increase the strength, it is preferable to repeat the precipitation heat treatment a plurality of times. When a plurality of precipitation heat treatments are performed, it is necessary to perform cold rolling between the precipitation heat treatments. By this cold rolling, a portion to be a precipitation site of Fe or an Fe-P compound is formed in the steel alloy sheet, and new precipitates are formed by the subsequent precipitation heat treatment. If the precipitation heat treatment is carried out a plurality of times, the density of the precipitate increases and the strength can be increased. When the precipitation heat treatment is carried out a plurality of times, the hardness after the precipitation heat treatment is increased from the first time to the second time and from the second time to the third time from the second heat treatment to the precipitation heat treatment conditions (temperature, time) It is necessary to appropriately select the cold rolling rate. That is, conditions for forming a precipitate having a circle-equivalent diameter of 10 to 40 nm are newly selected in addition to the precipitates existing before by the second and subsequent precipitation heat treatments. Concretely, for example, it is considered that the temperature of the precipitation heat treatment is lowered as the number of precipitation heat treatment is repeated. If the hardness after the precipitation heat treatment does not increase even when the number of times of the precipitation heat treatment is repeated, or conversely, if the hardness decreases, the precipitate becomes coarse, and the density of the fine precipitates does not increase.

Subsequently, final cold rolling is carried out to finish with a predetermined strength and plate thickness. After the final cold rolling, low temperature annealing (also referred to as deformation removal annealing) may be performed. With the miniaturization and high integration of the semiconductor device, the quality of the flatness of the plate and the reduction of the internal stress are increasingly demanded along with the miniaturization of the lead frame, and the low temperature annealing is effective for improving the quality thereof.

Example

After the copper alloy raw material was dissolved in a high frequency furnace, the components were adjusted and the ingot was agglomerated with a carbon mold (cooling method was water cooling) to obtain an ingot having a thickness of 50 mm, a width of 180 mm and a length of 100 mm. Table 1 shows the chemical composition of the obtained Fe-P type copper alloy. On the other hand, the Fe-P type copper alloy shown in Table 1 contains inevitable impurities in addition to the elements shown in Table 1, and contains 0.01 mass% or less of Ti, Zr, Be, V, Nb, Mo, The total amount of B, Na, S, Ca, As, Se, Cd, In, Sb, Pb, Bi and MM (Mish Metal) was 0.005 mass% or less. These elements are small in quantity and do not affect the properties of the Fe-P based copper alloy sheet according to the present invention.

Subsequently, each ingot was heated at 950 占 폚 for 1 hour and then hot-rolled until the thickness became 18 mm. After hot rolling, all the ingots were water-cooled. The termination temperature (cooling start temperature) of the hot rolling is as follows. 1 & tilde & 24, 750 < 0 > C. No. 24, since the time between passes is increased, the end temperature of the hot rolling is lowered. The cooling rates of the water cooling after the hot rolling were all 10 ° C / second or more.

No. Cold rolling, recrystallization heat treatment, precipitation heat treatment, final cold rolling and deformation removal annealing were carried out after the both surfaces of the hot rolled plates 1 to 28 were subjected to surface scraping to remove the oxide scale and to have a thickness of 16 mm, mm-thick Fe-P type copper alloy plate. On the other hand, the number of times of precipitation heat treatment is as follows. 1 to 10, 13 to 25, and 28 were 1 circuit. No. 11, 12, 26 and 27 were subjected to precipitation heat treatment twice, and after the first precipitation heat treatment, cold rolling was carried out at a processing rate of 60%.

Table 2 shows the process conditions of the hot rolling end temperature, the recrystallization heat treatment, the precipitation heat treatment, and the rolling rate of the final cold rolling.

The obtained Fe-P type copper alloy sheet was used as a blank material to measure average grain size, precipitate density, tensile strength, hardness before and after heating, conductivity, W bendability, solder heat releasability, and oxide film adhesion. The results are shown in Table 3. Further, the surface of the obtained Fe-P type copper alloy plate was observed under an optical microscope (magnification: 500 times) to investigate the presence or absence of coarse Fe particles generated by two-liquid phase separation or crystallization. No. of coarse Fe particles observed. 20, 21 and 23, a micrograph of the microscope is shown in Fig. The slightly dark gray particles are coarse Fe particles.

(Average crystal grain size)

The crystal structure of a cross section parallel to the rolling direction of the specimen and perpendicular to the sheet surface was observed with EBSD to determine the total grain size analyzed in terms of grain boundary conditions of 5 ° or more as the circle equivalent diameter, And the weighted average was obtained, and this was taken as the average crystal grain size of the disclosed material. Therefore, the average crystal grain size is calculated by the following equation.

Average crystal grain diameter = (a1 x d1 + ... + aN x dN) / A

Ai: area of each grain

    di: Diameter of each grain

    A is the sum of the areas of N grains.

(Precipitate density)

The structure of the sealant was observed with a transmission electron microscope at 150,000 times, and the number of precipitated particles having a particle diameter of 10 nm or more and 40 nm or less was measured to calculate the number of precipitated particles (unit / μm ² ) per unit area.

(The tensile strength)

A JIS-5 test piece having a longitudinal direction parallel to the rolling direction was prepared from the specimen and subjected to a tensile test according to the starting point of JIS Z2241.

(Hardness before and after heating)

The hardness before heating of the test piece taken from a specimen and the hardness after heating at 550 캜 for 1 minute were measured by applying a load of 4.9 N with a micro Vickers hardness meter. Then, the hardness ratio after heating / before heating was calculated. The hardness before heating was 180 Hv or higher and the hardness ratio after heating / heating was 0.90 or higher.

(Conductivity)

The specimen was processed by milling into a test specimen having a width of 10 mm and a length of 300 mm by short-form, and the electrical resistance was measured by a double-brittle resistance measuring apparatus and calculated by an average sectional area method. In the present invention, a conductivity of 50% IACS or more was evaluated as good.

(W bendability)

A 10 mm wide L.D. And T.D. The test piece was subjected to W bending (R / t = 1) in accordance with JCBA-T307, and the appearance of the bent portion was observed and evaluated. L.D. And T.D. (Good) that no cracks or surface roughening occurred in any of the specimens was evaluated as? (Poor) in which cracks occurred in any of the specimens,? (Poor) in which surface roughness occurred, and? On the other hand, the LD (Longitudinal to Rolling Direction) test piece is a test piece in which the longitudinal direction is the rolling parallel direction and the bending line is the rolling vertical direction, and the TD (Transverse to Rolling Direction) test piece is a longitudinal direction of the rolling direction, Means a specimen in a parallel direction.

(Solder heat-resisting peelability)

(Weak) active flux was applied to a test piece of a desk obtained from a publicly known material and immersed in a solder bath (Sn-3% Ag-0.5% Cu) kept at 245 캜 for 5 seconds, And heated. Thereafter, the test piece is subjected to 180 ° bending and bending back processing, and a transparent mending tape is stuck to the bending back processing portion and then peeled off to determine whether or not the solder of the processed portion is peeled off due to the presence or absence of the solder adhering to the mending tape Observed. (Good) was judged to be peeling when the peeling piece was attached to the mending tape, and it was evaluated as " Good (good) "

(Oxide film adhesion)

The oxide film adhesion was evaluated at an oxide film adhesion maintaining temperature. (10% sulfuric acid), followed by washing with water, followed by drying at various temperatures in the air for 5 minutes. Then, using a post-heating material, peeling with a tape The test was conducted. The heating temperature was changed by 10 DEG C, and the highest temperature at which the oxide film was not peeled was set as the oxide film adhesion maintaining temperature. The oxide film adhesion maintaining temperature was said to be at least 300 deg. Alkali cathode electrolytic washing liquid temperature: 60 ℃, cathode current density: 5A / dm ^2, time: was carried out under the conditions of 30sec. The cleaning liquid is an aqueous solution prepared by dissolving a typical commercially available alkali cathodic electrolytic cleaning agent containing sodium hydroxide as a main component (40%) and containing other phosphates, silicates, carbonates, and surfactants at a concentration of 50 g / L. The peeling test with a tape was carried out by a method in which a commercially available tape (mending tape made by Sumitomo 3M) was pasted and peeled.

Inventive No. 1 to 13 show that the composition of the copper alloy is within the specified range of the present invention, the finish temperature of the hot rolling is as high as 750 ° C or more, the heating and cooling rate of the recrystallization heat treatment is large, and the holding conditions are high temperature and short time. Therefore, it has a small average crystal grain size and a high precipitate density, and has high strength (including Vickers hardness) and heat resistance, good bendability, solder heat-releasability, and oxide film adhesion.

Among them, 11, and 12 show that the precipitation heat treatment was carried out twice, and the cold working rate between precipitation heat treatment was 60%. 1, the average crystal grain size is small, the precipitate density is high, and the strength is high.

On the other hand, 14 has a low conductivity and poor adhesion to the oxide film because the content of P is out of the specified range of the present invention.

No. 15 has a large crystal grain size, a low precipitate density, low strength (particularly Vickers hardness) and low heat resistance and poor bendability because the content of P is out of the specified range of the present invention.

No. 16 has a small average crystal grain size and a high precipitate density, and has high strength, heat resistance, and bendability. However, since the content of Zn is out of the specified range of the present invention, the solder heat-releasability is poor.

No. 17 has a small average crystal grain size, a high precipitate density, and high strength, heat resistance, and bendability. However, since the content of Zn is out of the specified range of the present invention, the conductivity is low.

No. 18 has a low content of Sn and Mg out of the specified range of the present invention, so that the average crystal grain size is small and the precipitate density is high, but the strength and heat resistance are low.

No. 19 has a low conductivity and a poor oxide film adhesion because the total content of Sn and Mg is out of the specified range of the present invention.

No. 20 has a large content of C out of the specified range of the present invention, so that a large number of coarse Fe particles are generated as shown in Fig. 1 (a), and when the plating of Ag or the like is performed, It is presumed that the plating ability is low. In addition, 20 had a large average crystal grain size, a low precipitate density, 2, the strength and heat resistance are low and the bendability is poor.

No. 21 has a large content of coarse Fe particles as shown in Fig. 1 (b) because the total content of Co, Si and Cr is out of the specified range of the present invention, and the plating property is low. In addition, 21 has a large average crystal grain size, a low precipitate density, 2, the strength and heat resistance are low and the bendability is poor.

No. 22 has a large average crystal grain size, a low precipitate density, low strength and heat resistance, and poor bendability because the content of Fe is out of the specified range of the present invention.

No. 23 has a small average crystal grain size and a high precipitate density, and has high strength, heat resistance, and bendability. However, since the content of Fe is out of the range specified in the present invention, as shown in Fig. 1 (c), a large number of coarse Fe particles are generated and it is presumed that the plating ability is low.

No. 24, the finish temperature of hot rolling is as low as less than 750 占 폚, which results in a large average crystal grain diameter, a low precipitate density, low strength and heat resistance, and poor bendability.

No. 25 has a small heating and cooling rate in the recrystallization heat treatment and a long-term maintenance condition at a relatively low temperature. Therefore, the average crystal grain size is large, the precipitate density is low, strength and heat resistance are low, and bendability is poor.

No. 26, since the temperature of the second precipitation heat treatment was the same as that of the first heat treatment, Compared with No. 12, the precipitate density and strength (including Vickers hardness) are lowered.

No. 27, the temperature of the second precipitation heat treatment is higher. Therefore, in the same composition, the heat treatment temperature of the No. (Including Vickers hardness) and heat resistance are lower than those of Comparative Examples 1 to 12. In addition, the average crystal grain size is large and the bendability is poor.

No. 28 has a high average crystal grain size due to a high retention temperature of the recrystallization heat treatment, low strength (particularly Vickers hardness), and poor bendability.

Claims (1)

At least one of Sn and Mg: 0.2 to 0.5 mass% in total, C: 0.003 mass% or less, Co, Si And Cr in a total amount of 0.05 mass% or less, the balance being Cu and inevitable impurities, and when a crystal structure parallel to the rolling direction and perpendicular to the plate surface is observed with EBSD, the circle equivalent diameter of each crystal grain is weighted a weighted average and it is 10μm or less, having a conductivity of 50% IACS or more, Vickers hardness of 180Hv or more, characterized in that the circle-equivalent diameter is a Fe or Fe-P compound is present in the precipitate particle density is at least 20 / μm ² of 10~40nm P-type copper alloy plate excellent in strength, heat resistance and bending workability.

Images