JP4781008B2 - Modified cross-section copper alloy plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a modified cross-section copper alloy plate having a thickness different in the plate width direction and a method for manufacturing the same, which are used for manufacturing electrical / electronic components such as lead frames, terminals and connectors.

Since a deformed cross-section copper alloy plate is often used for a large current member, it is necessary to have excellent heat dissipation and electrical conductivity, and high conductivity is regarded as important as an index. In addition, high heat resistance is required because it is necessary to withstand a heat history such as an assembly process for a semiconductor component, and bending workability is required in actual use.
For this reason, Cu-Fe-P-based copper alloys have been conventionally used for deformed cross-section copper alloy plates. For example, C19210 alloy (Fe: 0.05 to 0.15 mass%, P: 0.025 to 0.005). 040% by mass) is frequently used as a standard alloy because it is excellent in conductivity and heat resistance among copper alloys.

  The modified cross-section copper alloy plate is a flat plate processing step for manufacturing a flat plate having a constant thickness in the plate width direction from the ingot, and a modified processing for manufacturing a different cross-section plate having a different thickness in the plate width direction using the flat plate. Manufactured by a process. The flat plate processing step includes each step of soaking soaking, hot rolling, cold rolling, annealing, and cold rolling performed as necessary. The deforming process is performed after slitting the flat plate manufactured in the flat plate processing process to a necessary width, and includes cold processing, annealing, finishing cold processing, and correction processes performed as necessary. In some cases, annealing is not performed in the middle of cold working, and annealing is performed after finishing cold working. Note that the cold working in the deforming process is performed by cold rolling using a deformed roll, cold forging using a deformed die, or the like, and different processing methods may be combined.

Since the cross-section copper alloy sheet is required to have heat resistance, as described above, it is usually annealed in the middle or at the end of the deforming process, which was introduced in the deforming process. Dislocations can be released to ensure heat resistance. However, the production cost has been significantly increased by including this annealing step.
Under such circumstances, as described in Patent Document 1, a deforming process that does not include an annealing process has been proposed. This Patent Document 1 describes that softening due to recrystallization hardly occurs even when heated in a semiconductor element manufacturing process, but this point has not been proved.

JP 2003-136203 A

On the other hand, when the present inventors investigated the relationship between the presence / absence of the annealing step in the deforming process and the heat resistance using a copper alloy having a composition of Cu-0.10Fe-0.03P, the annealing step was omitted. It was found that the heat resistance deteriorates greatly.
FIG. 1 shows one method (annealing) described in Example 2 described later, and the other is annealing in the middle of cold rolling with a deformed roll (with annealing; conventional process). An irregular cross-section having the same cross-sectional shape is manufactured, a sample is cut out from each thin portion, the heat resistance test shown in Example 1 is performed, and the result is graphed. In the case of the material without annealing, the cold work rate of the thin-walled portion was 80%, and for the material with annealing, the cold work rate was 25% (cold work rate after annealing). Referring to FIG. 1, the heat resistant temperature (the temperature at which the Vickers hardness becomes Hv100) is 500 ° C. in the deformed section strip with annealing, whereas the deformed section strip without annealing is lowered to 340 ° C.

  The present invention has a high heat resistance, a high conductivity and an excellent bending workability in producing a deformed cross-section copper alloy sheet without annealing even once in the intermediate process or the final process. It aims at obtaining a cross-sectional copper alloy plate.

The deformed cross-section copper alloy sheet according to the present invention contains Fe: 0.03-0.3 mass%, P: 0.01-0.1 mass%, and Fe / P which is a mass ratio of Fe and P. Is 2.0 to 4.0 and contains Sn: 0.005 to 0.5% by mass, and is composed of the remaining copper and inevitable impurities. From a flat plate processing step of manufacturing a copper alloy flat plate having a certain thickness in the width direction, and a deforming step of cold processing the copper alloy flat plate to manufacture a deformed cross-section copper alloy plate having a different thickness in the plate width direction. Thus, it is characterized in that a deformed cross-section copper alloy sheet is obtained without annealing even once in the deformed processing step. The copper alloy may further contain Zn: 0.005 to 0.5%. Moreover, it is desirable that the cold working rate of the thin-walled portion is 30 to 90% in the deforming step.
In addition, the copper alloy plate as referred to in the present invention includes a coil-shaped plate (so-called strip).

  According to the present invention, a deformed cross-section copper alloy sheet having both high heat resistance, high conductivity, and bending workability can be manufactured at low cost without performing annealing once in the middle or at the end of the deforming process. .

Hereinafter, the modified cross-section copper alloy plate and the manufacturing method thereof according to the present invention will be specifically described.
First, the reason why the composition of the copper alloy according to the present invention is limited as described above will be described.
(Fe: 0.03-0.3 mass%)
Fe is an element necessary for improving heat resistance by precipitating as fine Fe—P precipitate particles in a copper alloy. If the content is less than 0.03%, fine precipitate particles are insufficient. Therefore, in order to effectively exhibit the effect of improving heat resistance, the content needs to be 0.03% or more. However, if the content exceeds 0.3%, an increase in conductivity cannot be achieved. Therefore, the Fe content is in the range of 0.03 to 0.3 mass%. In order to further increase the electrical conductivity, the Fe content is more preferably 0.2% by mass or less.

(P: 0.01 to 0.1% by mass)
P is an element necessary for improving the heat resistance of the copper alloy by forming a precipitate with the Fe in addition to having a deoxidizing action. If the content is less than 0.01%, fine precipitate particles are insufficient. Therefore, the content needs to be 0.01% or more in order to effectively exhibit the heat resistance improvement effect. However, if it exceeds 0.1% and is contained excessively, the electrical conductivity is lowered and the increase in electrical conductivity cannot be achieved. Moreover, hot workability also falls. Therefore, the P content is in the range of 0.01 to 0.1% by mass. In order to further increase the electrical conductivity, the P content is more preferably 0.07% by mass or less.

(Fe / P: 2.0 to 4.0)
In order to effectively precipitate fine precipitate particles and achieve high conductivity and high heat resistance, not only the individual content ranges of Fe and P but also Fe / P which is the mass ratio of Fe and P Must also be specified. When Fe / P is less than 2.0, P becomes excessive and is dissolved in the copper matrix, resulting in a decrease in conductivity and a high conductivity cannot be achieved. On the other hand, when Fe / P exceeds 4.0, on the contrary, Fe becomes excessive and coarsely generated as single Fe particles, resulting in a decrease in heat resistance. Therefore, Fe / P is set to a range of 2.0 to 4.0. In order to further increase the electrical conductivity, Fe / P is more preferably in the range of 2.5 to 3.5. In addition, prescribing Fe / P above also improves the heat-resistant adhesion of solder used for joining electronic components and Sn plating used to ensure the reliability of electrical contacts, and also suppresses thermal delamination. It is valid.

(Sn: 0.005 to 0.5 mass%)
Sn is an element necessary for improving the heat resistance of a copper alloy, but has an effect of greatly improving heat resistance in a very small amount, particularly in the coexistence with Fe and P. In order to exhibit this effect effectively, it is preferable to contain 0.005% or more. However, if it exceeds 0.5% and is contained excessively, the electrical conductivity is greatly reduced, and it is not possible to achieve high electrical conductivity. Therefore, the Sn content is in the range of 0.005 to 0.5 mass%. In order to further increase the electrical conductivity, the Sn content is more preferably 0.2% by mass or less.

(Zn: 0.005 to 0.5%)
Zn is an element effective in improving the heat-resistant adhesion of solder used for joining electronic components and Sn plating used for ensuring the reliability of electrical contacts and suppressing thermal delamination. In order to exhibit such an effect effectively, it is preferable to contain 0.005% or more. However, if it exceeds 0.5% and is contained excessively, it not only deteriorates the wetting and spreading properties of solder and molten Sn, but also decreases the conductivity. Therefore, Zn is selectively contained in the range of 0.005 to 0.5 mass%. In order to further increase the electrical conductivity, the Zn content is more preferably 0.2% by mass or less.

  Other elements such as Ni, Co, and Mn are impurity elements, which easily generate coarse crystals / precipitates, and easily cause a decrease in conductivity. Therefore, it is preferable to make the total content as small as possible 0.5% by mass or less. In addition, elements such as B, C, Na, S, Ca, As, Se, Cd, In, Sb, Pb, Bi, and MM (Misch metal) contained in a small amount in the copper alloy also have conductivity. Since it tends to cause a decrease, it is preferable to suppress the total content to 0.1% by mass or less as much as possible. In particular, As, Cd, and Pb are elements harmful to the environment, and each is preferably 0.005% or less, and more preferably 0.001% or less.

Next, the manufacturing method of the irregular cross-section copper alloy plate which concerns on this invention is demonstrated. This manufacturing method includes a flat plate processing step of manufacturing a flat plate having a certain thickness in the plate width direction from the ingot, and a deforming step of manufacturing a modified cross-section plate having a different thickness in the plate width direction using the flat plate. Become.
In the flat plate processing step, the copper alloy ingot having the above composition is heated or homogenized and then hot-rolled, and the hot-rolled plate is water-cooled. Thereafter, cold rolling is performed to produce a copper alloy flat plate having a certain thickness in the plate width direction, and annealing is performed. This annealing may be performed with or without recrystallization.

  There are two reasons for annealing at this stage. The first point is to precipitate Fe and P in a solid solution state as fine Fe-P precipitates, thereby achieving high conductivity and high heat resistance. The second point is to ensure the bending workability at the same time as securing the heat resistance after forming the deformed cross-section plate by annealing before the deforming process. Since heat resistance and bending workability decrease as the cold working rate applied to the material increases, the heat resistance and bending workability are greatly reduced if annealing is not performed at this point. At the time after annealing, the size of the crystal grains (average crystal grain size measured in the plate width direction) is preferably 50 μm or less, and more preferably 20 μm or less. If the size of the crystal grains exceeds 50 μm, the bending workability after forming a deformed cross-section plate is lowered, and the heat resistance is also reduced.

  In the modified cross-section processing step, a deformed cross-section copper alloy plate having a different thickness in the plate width direction is formed by cold-working the annealed flat plate. This cold working can be performed by various processing methods such as cold rolling using a deformed roll or cold forging using a deformed die, and can also be performed by combining different processing methods. In the modified cross-section processing, it is desirable that the cold working rate of the thin portion is 90% or less, and more desirably 85% or less. This is because heat resistance and bending workability gradually decrease as the cold work rate after annealing increases. Further, the cold working rate of the thin wall portion is 30% or more, preferably 50% or more. This is because if it is less than 30%, there is no shortage of heat resistance even if Sn is not added, and if it is 50% or more, the effect of improving heat resistance by adding Sn is increased. In general, the thickness ratio of the thin-walled portion to the thick-walled portion of the odd-shaped cross-section copper alloy plate for electric / electronic parts is about 1: 1.5-6.

Examples of the present invention will be described below. In this embodiment, a copper alloy flat strip having a certain thickness in the plate width direction is manufactured using a copper alloy having a composition of Cu-0.10Fe-0.03P-0.03Sn. Various cross-sections were processed at various cold working rates, and heat resistance tests were performed on the obtained cross-section copper alloy strips.
Specifically, a copper alloy ingot having the above composition was produced in a melting furnace, hot-rolled at 900 ° C., and water-cooled to a thickness of 15 mm. Then, after chamfering the surface of the rolled plate to remove the oxide scale, it is cold-rolled to a thickness of 2 mm to produce a copper alloy flat strip having a certain thickness in the plate width direction, and recrystallization annealing is performed. After that, deformed cross-section copper alloy strips were manufactured at various cold work rates (cold work rate of 15 to 90% for thin-walled portions) by cold rolling with a deformed roll.

In the heat resistance test, a sample was cut out from the thin-walled portion of each irregular cross-section copper alloy strip, heated at various different temperatures for 5 minutes, and then measured for Vickers hardness Hv. The measurement of Vickers hardness was performed by applying a load of 4.9 N (0.5 kg) with a micro Vickers hardness tester.
FIG. 2 is a graph showing the results of the heat resistance test. As can be seen from FIG. 2, the heat resistant temperature (the temperature at which the Vickers hardness becomes Hv100) decreases as the cold working rate increases. However, the heat-resistant temperature obtained from the graph of FIG. 2 is 440 ° C. when the cold work rate is 80%, which is 100 ° C. higher than the 340 ° C. of the conventional copper alloy strip not containing Sn (see FIG. 1). is doing.

In this example, a copper alloy flat strip having a certain thickness in the sheet width direction is manufactured using the copper alloys having the respective compositions shown in Table 1, and then a modified cross-section copper alloy strip is manufactured by performing a modified cross-section processing. Each characteristic was evaluated.
Specifically, a copper alloy strip having a thickness of 2 mm is manufactured by the same process as in Example 1, and after recrystallization annealing, a deformed section copper alloy strip having the following dimensions is formed by cold rolling with a deformed roll. Manufactured. The cold working rate is 80% for the thin portion and 25% for the thick portion.
・ Thin part thickness: 0.40mm
-Thick part thickness: 1.50 mm
・ Width of thin part: 30mm
-Thick part width: 25mm

A sample was cut out from the thin-walled portion of the deformed cross-section copper alloy strip obtained in this way, a heat resistance test was performed in the same manner as in Example 1, the result was graphed, and the heat resistance temperature (temperature at which the Vickers hardness becomes Hv100). The electrical conductivity was measured and the bending workability and the solder heat-resistant adhesion test were performed in the following manner. These results are shown in Table 1.
The electrical conductivity was calculated by an average cross-sectional area method by processing a strip-shaped test piece having a width of 10 mm and a length of 300 mm by milling, measuring the electrical resistance with a double bridge resistance measuring device.

The bending workability is determined by conducting a W bending test [R (bending radius) / t (sheet thickness) = 2, bending axis parallel to rolling direction) defined in JBMA-T307 standard of copper elongation association, and observing the surface of the bending portion. Thus, it was evaluated in five stages (A: no wrinkle, B: small wrinkle, C: large wrinkle, D: small crack, E: large crack). A to C are acceptable levels, and D to E are unacceptable levels.
The solder heat-resistant adhesion is determined by immersing the sample in Sn-40% Pb solder at 245 ° C. for 5 seconds to join the solder to the sample surface, heating the sample at 150 ° C. for 500 hours, and then bending back 180 ° (bending R = 2 mm), and the adhesion of the solder inside the bend was evaluated in three stages (◯: no peeling, Δ: minute peeling, ×: whole surface peeling).

As shown in Table 1, No. including invention sample Nos. 1-10 are Nos. With insufficient Sn content. 11-13 and No. with insufficient Fe and P contents. No. 15, 17 and 19 are superior in heat resistance and have an excessive Sn content. 14 and No. 14 with excessive Fe and P contents. No. 16, which has a higher electrical conductivity than those of Nos. 16, 18, and 20 and whose Fe / P ratio is not within the range of 2 to 4. Compared to 21 and 22, the conductivity is excellent, and the solder heat-resistant adhesion is also excellent. In addition, when the Fe and P contents are excessive, Bending workability is superior to 16,18,20.

It is a graph which shows the result of the heat resistance test using the irregular cross-section copper alloy strip of the conventional composition. It is a graph which shows the result of the heat resistance test using the irregular cross-section copper alloy strip of the composition of the present invention.

Claims (5)

Fe: 0.03-0.3 mass%, P: 0.01-0.1 mass%, Fe / P which is a mass ratio of Fe and P is 2.0-4.0, And Sn: 0.005-0.5% by mass and Zn: 0.005-0.5% , consisting of the balance copper and inevitable impurities, after the precipitation annealing of Fe-P, by cold working, the plate width direction A deformed cross-section copper alloy sheet , which is subjected to deformed cross-section processing having a different thickness and has not been annealed once in the middle or at the end of the deformed cross-section processing step . The deformed cross-section copper alloy sheet according to claim 1 , wherein the cold working rate of the thin wall portion is 30 to 90%. A flat plate processing step of manufacturing a copper alloy flat plate having a certain thickness in the plate width direction from the copper alloy ingot, and a deformed cross-section copper alloy plate having a different thickness in the plate width direction by cold working the copper alloy flat plate It consists of a deforming process to be manufactured, and the composition of the copper alloy contains Fe: 0.03-0.3 mass%, P: 0.01-0.1 mass%, and the mass ratio of Fe and P A certain Fe / P is 2.0 to 4.0 and contains Sn: 0.005 to 0.5% by mass and Zn: 0.005 to 0.5% , and consists of the balance copper and inevitable impurities, A method for producing a deformed cross-section copper alloy plate , wherein after the precipitation annealing of Fe-P in the flat plate processing step, a deformed cross-section copper alloy plate is obtained without being annealed even once in the deformed processing step. 4. The method for producing a deformed cross-section copper alloy plate according to claim 3 , wherein in the deforming step, the cold work rate of the thin portion of the deformed cross-section copper alloy plate is set to 30 to 90%. A deformed cross-section copper alloy sheet manufactured by the method according to claim 3 or 4 .

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