JPS63250444A - Manufacture of high-conductivity terminal and connector material excellent in migration resistance - Google Patents

Abstract

PURPOSE:To develop a copper alloy excellent in migration resistance, by hot- rolling an ingot of Cu alloy containing An and other specific elements and then by subjecting the hot-rolled plate to cooling, cold working, annealing, temper finish rolling, and final annealing under specific conditions. CONSTITUTION:An ingot of a Cu alloy containing, by weight, 0.35-1.0% Fe, 0.05-0.35% P, 0.05-1.0% Sn, and 1.0-5.0% Zn is subjected to primary hot rolling at <=714 deg.C to prevent the cracking of a rolled stock and successively to secondary hot rolling, which is cooled from >=600 deg.C at <=5 deg.C/sec cooling rate to undergo solution heat treatment. Subsequently, the hot-rolled plate is cold-rolled and the resulting cold-rolled sheet is annealed at 400-600 deg.C for 5min-4hr to precipitate FeP and improve strength and electric conductivity. Successively, the above sheet is subjected to temper finish rolling and then annealing at 250-600 deg.C for 5sec-4hr, so that high-conductivity Cu alloy for terminal and connector materials excellent in migration resistance can be manufactured.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for producing highly conductive terminal/connector materials with excellent migration resistance, and more specifically, with conductivity of 50% I AC3 or higher. The present invention relates to a method for manufacturing a copper alloy for terminals and connectors that has excellent migration resistance.

[Prior Art] Modern electrical and electronic components are becoming smaller, more densely packaged, and have a larger current capacity due to the need to be lighter, thinner, shorter, and smaller.

Therefore, materials with high conductivity and high strength are required for terminals and connectors, and in terms of performance, they are required to have the strength of phosphor bronze, and have a conductivity of 50% IAC3 or higher. ing. Furthermore, with the miniaturization and increase in the number of electrodes in terminals and connectors, the pitch between electrodes has decreased from 1/10 inch (2.54 mm) to 1/20 inch.
inch (1,27 mm), 1/40 inch (0,635
mm). In general, brass is mainly used as the terminal material as described above, and phosphor bronze has been used particularly as a high-grade connector material.

[Problems to be Solved by the Invention] Brass used as a terminal/connector material has the advantage of good moldability, but is inferior to phosphor bronze in stress relaxation properties and corrosion cracking resistance. Moreover, the pitch between the electrodes of electrical and electronic components is becoming smaller, and moisture condensation and moisture infiltration; when moisture adheres between the electrodes, copper ions from pure copper and phosphor bronze are eluted, causing copper to migrate between the electrodes. ) There is a problem in that it causes problems such as short circuits in electric circuits. In addition, as shown in the Shiraki Industrial Standard (JIS), phosphor bronze contains 3.0 wt% or more of Sn, and not only has the electrical conductivity as low as 22% IACS or less, but tin itself is expensive. Therefore, phosphor bronze is also expensive. Conventional phosphor bronze has the drawback of not being able to meet the needs for lighter, thinner, shorter and more compact materials and increased current capacity in terms of heat resistance or stress relaxation properties at elevated temperatures. Here, Cu-Fe-P type or Cu-Fe-P-3nf is used as a copper alloy that has both high conductivity and high stiffness.
− alloys are known. This alloy system exhibits high strength without impairing the high conductivity of the matrix due to the precipitation of Fe-P compounds, and has the following characteristics: It satisfies the above requirements regarding conductivity and strength.

As an alloy belonging to this alloy system, C'19600 (Cu
-1wt%Fe-0,3wt%P) and are used as wire rods, but are not generally produced as strips or plates. The reason for this is that this alloy type alloy is difficult to hot-roll. It is extremely difficult to mass produce strips or plates commercially, except for hot extruded wire rods. On the other hand, horizontal continuous casting and cold rolling can be considered as a method for mass producing strips or plates of this alloy other than hot rolling, but the manufacturing costs are extremely high compared to the hot rolling method. Therefore, it is inappropriate to apply this method to terminal/connector materials for which cost reduction is required. Therefore, the present invention improves migration resistance by enabling hot rolling of Cu-Fe-P or Cu-Fe-P-3nJs alloys, which are difficult to hot-roll and whose strips or plates are not yet manufactured. The purpose of this project is to develop a method for manufacturing superior highly conductive terminal and connector materials.

[Means for Solving the Problems 1] The method for producing a highly conductive copper alloy for terminals and connectors with excellent migration resistance according to the present invention is characterized by: Fe: 0.35 to 1.0 wt%; P:0.05~0
．． 35wt%, Sn: 0.05-1.0wt%, Zn
: 1. O to 5.0 wt%, and the remainder is substantially Cu.
The copper alloy ingot is hot rolled for the first time at a temperature not exceeding 714°C, then hot rolled for the second time, and then rolled at a speed of 5°C/sec or more from a temperature of 600°C or higher. After cooling and annealing at a temperature of 400 to 600°C for 5 minutes to 4 hours after cold working, temper finish rolling is performed, and then 25
The purpose is to perform annealing at a temperature of 0 to 600°C for 5 seconds to 4 hours.

First, the components of the copper alloy used in this manufacturing method will be explained. When Fe is contained in coexistence with P, it forms iron phosphide, which has the effect of improving strength and having excellent stress relaxation properties at high temperatures. However, the Fe content is 0.3
If P is less than 5 wt%, even if the P content is 0.05 to 0.35 wt%, the effect of improving strength is small;
If the content exceeds 0 wt%, P is 0.05 to 0.35
Even if it is contained in wt%, Fe is dissolved in solid solution in the matrix and reduces the electrical conductivity. Therefore, the Fe content is set to 0.35 to 1.0 wt%.

If the P content is less than 0.05 wt%, even if it is contained coexisting with Fe, no improvement in strength or stress relaxation properties can be expected, and if it is contained in more than 0.35 wt%, , when the Fe content is 0.35 to 1.0 wt%, P that cannot completely form iron phosphide remains in the matrix, reducing the electrical conductivity. Therefore, the P content is set to 0.05 to 0.35 wt%. Further, it is preferable that Fe and P be contained in a ratio close to 3:1 (wt%) of Fe and P.

Sn is an element that improves strength and spring limit value by solid solution in Cu, and the content m is 0.05wt.
If the content is less than 1.0 wt%, no improvement in strength and spring limit value can be expected even if Fe and P are contained together, and if the content exceeds 1.0 wt%, hot workability will decrease. Furthermore, the conductivity decreases below 50% I AC5. Therefore, the Sn content is set to 0.05 to 1.0 wt%.

Zn is an essential element for improving migration resistance, which is a feature of the present invention. Zn is Cu-F with voltage applied
It is an essential element for suppressing the progress of Cu migration and suppressing leakage current when water condenses or enters between the electrodes of e-P-Sn alloys, and also provides peeling resistance of plated Sn and solder. It is an element that significantly improves If the Zn content is less than 1.0 wt%, the migration suppressing effect will be small, and if the Zn content exceeds 5.0 wt%, the progress of migration will be suppressed.
Although it has the effect of suppressing leakage current, unfavorable properties such as deterioration of soldering properties, easy occurrence of stress corrosion cracking, and reduction in electrical conductivity appear. Therefore,
The Zn content is 1.0 to 5.0 wt%. Here, the remainder represents elements other than the above-mentioned additive elements, and consists of inevitable compounds and Cu.

Next, the manufacturing process will be explained.

When the copper alloy of the present invention having the above-mentioned components is hot-rolled under normal hot-rolling conditions, for example, heated to a temperature of 850° C., cracks occur at the grain boundaries and cannot be rolled. The reason for this is that the cracks are caused by P segregated at the grain boundaries, and as is clear from the binary phase diagram of copper and phosphorus shown in Figure 1, when the amount of P segregated at the grain boundaries exceeds 1.75 wt%, At 714° C., a reaction of α+Cu, , P−$L occurs, and a liquid phase is generated at the grain boundaries.

Such segregation is unavoidable using normal agglomeration methods, and therefore, cracking will occur if hot rolling is performed at a temperature exceeding 714°C.

For this reason, the first hot rolling is carried out at a temperature not exceeding 714°C. The lower limit temperature of hot rolling is preferably 650° C. or higher, preferably as close to 714° C., from the viewpoint of lowering the rolling load.

Furthermore, after the second hot rolling, cooling is performed at a rate of 5°C/second or more from a temperature of 600°C or higher to perform solution treatment, and at a temperature of less than 600°C, cooling is performed at a rate of 5°C/second or more. Even if the cooling rate is 5°C/second or more, precipitation has already occurred, and the effect of the solution treatment is insufficient.
If the temperature is less than 2 seconds, precipitation will occur during cooling even if the temperature is 600° C. or higher, and the effect of the solution treatment will be insufficient.

The temperature at which the above-mentioned cooling is completed is set to a temperature at which precipitation does not occur during cooling due to the effect of solution treatment.

Therefore, the reason for performing the second rolling is to perform solution treatment, and therefore, the lower limit of the second hot rolling temperature is 600 ° C. or higher, which is the above-mentioned condition after the completion of rolling.
The upper limit is preferably 950°C or less from the viewpoint of energy saving.

714 Cracks occur in the first rolling compared to the second rolling.
The reason why it may be carried out at a temperature higher than 0.degree. C. is that the factors that cause hot rolling cracks have been removed in the first rolling. That is, the reason why cracks occur during hot rolling is that continuous pores or voids are generated in the traces of the diffusion of the liquid phase generated at the grain boundaries as described above, which causes cracks.

However, if rolling is performed in advance at a temperature of about 700°C or lower, Cu = P present at the grain boundaries will be uniformly dispersed, thereby preventing the above-mentioned liquid phase from occurring at the grain boundaries, and rolling at a temperature of about 714°C or higher will prevent the formation of the above-mentioned liquid phase at the grain boundaries. This is because melting and continuous pores, which cause cracks, do not occur even when heated to a certain temperature.

After cold working, annealing is performed at a temperature of 400 to 600° C. for 5 minutes to 4 hours to precipitate iron phosphide, which improves electrical conductivity and strength. But 400
At temperatures below .degree. C., precipitation is insufficient even if annealing is performed for 5 minutes to 4 hours, and when the temperature exceeds 600.degree. C., solid solution of the precipitates begins again. Therefore, the temperature is set at 400 to 600°C. If the time is less than 5 minutes, precipitation will be insufficient even if annealed at a temperature of 400 to 600°C, and if it exceeds 4 hours, it is not preferred from the viewpoint of energy saving. Therefore, the annealing time is 5
Minutes to 4 hours.

After performing temper finish rolling, annealing is performed at a temperature of 250 to 600°C for 5 seconds to 4 hours in order to recover the elongation decreased by cold rolling and remove residual stress caused by rolling. At temperatures below 250°C, this effect is small, and at temperatures above 600°C, solid solution of precipitates occurs again. Therefore, the temperature is set at 250 to 600°C. If the time is less than 5 seconds, the above-mentioned effects will be small, and if it exceeds 4 hours, it is not preferable from the viewpoint of energy saving. Wait for 5 seconds to 4 hours.

[Example] Examples of the method for producing a highly conductive copper alloy for terminals and connectors with excellent migration resistance according to the present invention will be described.

An alloy having the composition shown in Table 1 was melted in the atmosphere, and an ingot of 410wxlSOtx4000ffim was formed by semi-continuous casting. This ingot was hot-rolled to a thickness of 15 mm under the conditions shown in Table 2, then water-cooled from a temperature of 600°C or higher, and the front and back sides were faceted by 0.5 mm to a thickness of 0.5 mm.
Cold rolling was carried out until then. Then 240℃ at a temperature of 450℃
After annealing for 1 minute and rough cold rolling to a thickness of 0.25 mm, annealing was performed at a temperature of 275° C. for 120 minutes.

Table i2 shows the results of tensile strength and conductivity tests using stiff materials and the results of hot rolling.

The test method is as follows.

(1) For the tensile test, a JIS No. 13 B test piece cut in the rolling direction was used.

(2) Electrical conductivity was measured using a double bridge using a 10 mmw, 300 mm JZ specimen.

As is clear from Table 2, Nos. 001 to 6 are examples of the present invention, which were hot rolled twice, and good hot rolling results were obtained. The tensile strength is higher than that of the comparative example and the conventional example <61.2~64, 7 K g f /
It is also seen that a high conductivity of 50% I ACS or higher can be obtained.

Moreover, N097-9 shows comparative examples, and 900℃
Severe cracking occurred during one hot rolling at a temperature of . Furthermore, Nos. 10 to 12 also show comparative examples, and 75
When hot rolling was carried out once at a temperature of 0° C., small cracks occurred and the solution treatment was insufficient, so both the tensile strength and the electrical conductivity were lower than those of the examples. From these results, it can be seen that the example has the strength of a type of phosphor bronze, which is the object of the present invention, and a conductivity of 50% IACS or more.

Next, using the materials of the examples shown in Table 2, experiments were conducted on spring limit values and migration resistance.

Table 3 shows the experimental results. Migration resistance was expressed as maximum leakage current.

The test method is as follows.

(1) Spring limit value test is conducted with a width of 10 mm parallel to the rolling direction.
The moment test was conducted using a test piece as specified in JISH3130.

(2) Regarding migration resistance, 0.3 mmt
A set of two test pieces measuring 3.0 mm x 80 mm J2 was adjusted to prepare a test piece, and the maximum leakage current value when a DC voltage of 12 V was applied was measured and used as a criterion.

The details are described below.

As the test pieces, two plate-shaped test pieces 1 as shown in FIG. 2 were used. A 1 mm thick ABS resin 2 was interposed between the two test pieces 1, and press plates 3 were provided at both ends of the ABS resin 2, and the test piece 1 was pressed and fixed with a clip 4 from above. Further, an electric wire 5 was electrically connected to each of the test pieces 1 at its ends.

This electric wire 5 is connected to a battery 6.

A dry-wet test was conducted on the test piece 1 placed in the above condition by applying a DC voltage of 12V while immersing it in tap water for 10 minutes, then drying it for 10 minutes, and the maximum leakage current value was determined up to 50 cycles. was measured using HiCorder Memory 8802 (Hakuga Denkisha) (not shown).

As is clear from Table 3, Nos. 11 to 3 are examples of the present invention, Nos. 4 to 8 are comparative examples, and the spring limit values Nos. 1 to 3 are 61.4 to 62.1. gf/mm
It can be seen that this value is close to or exceeds the maximum value of 61.8 Kgf/mm2 of the comparative example.

Furthermore, the maximum leakage current indicating migration resistance is 0.
The value was 27 to 0.3 ampere, which is one digit lower than the comparative example No. 4.5.7, which indicates that the migration resistance is excellent.

Comparative example No. 6.8 has a maximum leakage current close to that of this example and has excellent migration resistance, but the spring limit value is 60.4 gf/mm2, 30. I
Kgf/mm2, which is a lower value than the example. From this, it can be seen that the examples have excellent migration resistance, which is the object of the present invention, and also have a high cover spring limit value.

[Effect of the invention] As explained above, Cu-Fe-P system or Cu-Fe
By making it possible to hot-roll -P-Sn alloys, it has become possible to produce highly conductive terminal/connector materials with excellent migration resistance.

[Brief explanation of drawings]

FIG. 1 is a graph showing a binary phase diagram of copper and phosphorus, and FIG. 2 is a plan view and a side sectional view showing an apparatus for testing migration resistance. 1... Test piece, 2--ABS resin, 3-- Pressing plate, 4
...Clip, 5...Wire, 6...Battery,
7...Discharge hole (10mm) Figure 1

Claims (1)

[Claims] Fe: 0.35-1.0wt%, P: 0.05-0.3
5wt%, Sn: 0.05-1.0wt%, Zn: 1.
A copper alloy ingot containing 0 to 5.0 wt% with the remainder substantially consisting of Cu was hot rolled for the first time at a temperature not exceeding 714°C, and then hot rolled for the second time. After, 6
After cooling at a rate of 5°C/sec or more from a temperature of 00°C or higher, annealing at a temperature of 400 to 600°C for 5 minutes to 4 hours after cold working, and then performing temper finish rolling. ~6
1. A method for producing a highly conductive terminal/connector material with excellent migration resistance, which comprises annealing at a temperature of 00° C. for 5 seconds to 4 hours.