JPH10265874A - Copper alloy for electrical/electronic parts and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copper alloy for the electrical/electronic parts which is excellent in elongation.bending workability, solder wettability, adhesibility with solder, etc., is easy for pickling, supresses generation of a Sn plating whisker and is excellent in a wear quantity reducing effect of an opponent material of a press die, etc. SOLUTION: The copper alloy contains, by weight, 0.2-12% Sn, 0.1-12% Zn, 0.001-0.4% P, 0.0005-0.015% Pb, satisfying a Zn/Sn ratio of <=1, further 0.0001-0.4 a total quantity of one component or more among 0.0001-0.1% Cr, 0.0001-0.1% Mn, 0.0001-0.1% Al, 0.0001-0.1% Si, further <=0.005% in total and <=0.003 in individual among Bi, As, Sb, S and the balance Cu with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a copper alloy for electric / electronic parts. In addition, the electric / electronic parts mentioned here include diodes, transistors, photoelectric conversion elements, thyristors, lead frames for semiconductor elements such as triacs, connection parts such as terminals and connectors, electric contacts and sliding parts such as switches, Also included are sliding parts such as brushes and ground terminals such as motors and copy drums.

[0002]

2. Description of the Related Art Phosphor bronze (JIS C511) which has a relatively low conductivity but has high moldability and excellent moldability is used as the copper alloy for electric / electronic parts.
1, C5102, C5191, C5212, C521
0) has been frequently used. Phosphor bronze is a solid solution strengthened alloy of Sn, and the required strength-elongation balance, formability, and spring characteristics have been obtained by controlling the amount of Sn added and the processing rate. However, the lowering of the bending limit due to the anisotropy of the mechanical properties in the material longitudinal direction (rolling direction) and the direction perpendicular to the rolling direction caused by the rolling process and the reduction in ductility are required for copper alloys for electric and electronic parts. Are no longer satisfying the objective properties.

[0003] In addition, with the decrease in the area of solder joints for terminals and connectors accompanying the recent miniaturization of electronic equipment, phosphor bronze has inferior adhesion to molten solder, solder and Sn plating. However, there is a problem that the reliability at the time of mounting is low unless a base plating treatment of Cu, Ni or the like for preventing peeling is performed.

[0004] Further, in phosphor bronze containing Sn, Sn oxide is easily formed on the surface in the annealing step. The presence of this Sn oxide deteriorates the solder wettability and the plating property. In addition, Sn oxide has a Mohs hardness higher than that of tool steel, and reduces the life of a press die during press punching and press molding, and when used as a sliding mechanism component, the mating material There was a problem of severe wear.
In order to remove the Sn oxide film, a two-stage pickling as shown in JP-B-6-33473 (first pickling with sulfuric acid to which a hydrogen peroxide solution is added, followed by acid ammonium fluoride) (Secondary pickling with sulfuric acid containing), but the number of pickling steps is increased compared to other copper alloys (copper alloys not containing Sn), and furthermore, harmful pickling waste liquid containing fluoride and the like is removed. Since it requires processing equipment and processes, it tends to be a factor of cost increase.

[0005] Phosphor bronze generates whiskers when Sn plating is performed. In order to prevent this whisker, a method has been adopted in which an undercoating treatment of Cu, Ni, etc., which cancels the influence of the base material, is performed, or an Sn plating material whose surface is treated by a method generally called a reflow Sn plating method is used. . In Sn post-plating performed for the purpose of ensuring solder wettability of electric / electronic parts, improving corrosion resistance, and increasing the effective area of electric contacts, the plating composition of Sn plating is set to 90% Sn-10 as a more reliable method. % Pb
And the like, and the generation of Sn plating whiskers has been suppressed. However, in recent years, elements such as Pb in the solder that is easily eluted by rain or the like from the standpoint of environmental protection have begun to be strictly regulated, and thus Sn plating whiskers have become a problem again.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional phosphor bronze, and has been made in view of elongation characteristics, bending workability, solder wettability, adhesion of solder, solder plating and Sn plating. Excellent in acidity, easy to pickle,
An object of the present invention is to obtain a copper alloy for electric / electronic parts in which the generation of Sn plating whiskers is suppressed, and which is excellent in the effect of reducing the amount of wear of a counterpart material such as a press die.

[0007]

The copper alloy for electric / electronic parts according to the present invention comprises: Sn: 0.2 to 12% by weight, Zn:
0.1 to 12% by weight, P: 0.001 to 0.4% by weight,
Pb: 0.0005 to 0.015% by weight is contained so that the Zn / Sn ratio becomes 1 or less.
1 to 0.1% by weight, Mn: 0.0001 to 0.1% by weight, Al: 0.0001 to 0.1% by weight, Si: 0.0
0.0001 to 0.4% by weight in total of one or more components selected from the group consisting of 001 to 0.1% by weight;
The contents of Bi, As, Sb, and S are individually 0.003% by weight or less, and the total amount is 0.005% by weight or less, with the balance being Cu and unavoidable impurities.

The copper alloy for electric / electronic parts may further contain one of Fe and Ni if necessary.
~ 1.0 wt%, or both in a total of 0.0005-
2.0% by weight. This copper alloy for electric / electronic parts has an O content of 50 from the viewpoint of production or practical use.
ppm or less, and the H content is regulated to 20 ppm or less,
In addition, it is desirable that both the crystal grain size in the sheet thickness direction in the cross section parallel or perpendicular to the rolling direction be smaller than 20 μm.

The reasons for limiting the content of each additive element will be described below. (1) Limiting Sn Content Sn has an effect of improving mechanical properties such as strength and a spring limit value. In particular, the greater the amount of Sn added, the better the balance between strength and elongation, and a larger elongation can be obtained for the same strength. However, if the Sn content is less than 0.2%, the above effects cannot be obtained, and work hardening is difficult, so that even if the final rolling reduction ratio is adjusted, elongation can be obtained only 3% or less. It is not suitable for electronic components. On the other hand, if it is added in excess of 12% by weight, a γ phase is generated, and the cold workability is degraded, making the production of a sheet material difficult. Therefore, the content of Sn is set to 0.2 to 12% by weight. Note that a desirable range of the Sn content is 0.5 to 12% by weight.

(2) Restriction of P content P is a deoxidizing material for completely deoxidizing the molten metal and obtaining a sound ingot, and when the content is less than 0.001%, Zn is contained in 0.1%. Addition of 1% by weight or more results in insufficient deoxidation.
If it exceeds 0.4% by weight, the solder wettability will decrease. Therefore, the content of P is set to 0.001 to 0.4% by weight. A desirable range of the P content is 0.01 to 0.3.
% By weight.

(3) Restriction of Zn content By adding Zn to phosphor bronze, elongation characteristics and bending workability are improved, and solder, solder plating, and Sn plating are performed without deteriorating the advantages of phosphor bronze. This improves the adhesion of the steel sheet, facilitates pickling, suppresses the occurrence of Sn plating whiskers, and reduces the amount of wear of a counterpart material such as a press die. The improvement of the elongation characteristics here means that the alloy whose Zn content is within the range of the present invention is parallel to the rolling direction at the final thickness in comparison with the alloy whose Zn content is below the range of the present invention. Finish rolling rate required to obtain the same tensile strength in different directions or perpendicular directions (rolling rate for each tempering adjustment after finish annealing to adjust the recrystallized grain size of the final product) is small Means that the elongation in each of the directions parallel and perpendicular to the rolling direction is greater.

However, if Zn is less than 0.1% by weight, the above effects cannot be obtained. On the other hand, when the content exceeds 12% by weight, the solder wettability decreases and dezincification corrosion occurs. Therefore, the content of Zn is set to 0.1 to 12% by weight. Note that a desirable range of the Zn content is 0.5 to 10% by weight. In addition, Z is expressed as a ratio of weight% in the chemical composition of the alloy.
If the n / Sn ratio exceeds 1, the solder wettability deteriorates, or the growth rate of the alloy layer formed at the interface between the solder and the solder plating and the base material is high, and the whitening of the solder and the solder plating (solder and solder plating layer) Is a phenomenon in which it is brittle from the interface of the base material to the surface, has low electrical conductivity, and changes into an alloy layer having poor solder wettability). In addition, Zn is preferentially eluted out of the alloy constituent elements during pickling, followed by Sn,
A dezincification corrosion phenomenon in which a Cu phase containing P or the like remains. Therefore, the Zn / Sn ratio is set to 1 or less.

(4) Restriction of Pb Content The addition of Pb reduces the abrasion of the die during press punching and press forming, reduces the reduction in wear of the mating material when used as a sliding mechanism part, and Is effective in improving machinability.
However, there is no effect unless 0.0005% by weight or more is added. On the other hand, Pb does not form a solid solution in Cu,
If it is added in excess of 015% by weight, local precipitation is likely to occur in the form of a thin film at the crystal grain boundaries, and since it has a low melting point, it particularly hinders hot workability. Therefore, the content of Pb is 0.0005 to 0.5.
015% by weight. Note that a desirable range of the Pb content is 0.0005 to 0.001% by weight.

(5) Reasons for limiting the content of the selected element When Cr, Mn, Al, and Si are added at the time of melting and casting, there is an effect as a deoxidizer. These elements are 0.0
When 001% by weight or more remains, it is effective as a deoxidizing material,
In addition, it does not adversely affect the alloy of the present invention as a base material. As another effect, when Cr and Mn are added in an amount of 0.0001% by weight or more, grain boundary strengthening can be achieved. further,
Cr can be improved in creep properties and heat resistance by subjecting it to appropriate processing and heat treatment to uniformly and finely disperse the precipitates. However, these elements are 0.1% by weight
When Cr is contained in excess of Cr, the viscosity of the molten metal is increased and castability is deteriorated, and coarse crystals are more likely to be generated. The upper limit is 1% by weight.

The addition of Al is effective for desulfurization and solid solution strengthening of the molten copper alloy. Al is added to the molten metal to form an Al-S compound having a lower specific gravity than the copper molten metal, and is removed as slag. At this time, 0.0001% by weight or more of Al remains, but this also has no adverse effect on the characteristics, and further addition of Al results in an improvement in strength because Al is a solid solution strengthening element. On the other hand, if added in excess of 0.1% by weight, a strong oxide film which cannot be removed by the pickling solution and polishing used in the production process of phosphor bronze is formed on the surface of the plate material, and the cold Significantly impairs processability and product value. Further, the addition of Si is performed by selectively adding Ni or F.
e and a compound to improve the strength of the alloy,
When added in excess of 0.1% by weight, it is selectively oxidized on the surface of the sheet material during annealing, and reduces solderability and plating property. Therefore, these selected elements are Cr: 0.000
1 to 0.1% by weight, Mn: 0.0001 to 0.1% by weight, Al: 0.0001 to 0.1% by weight, Si: 0.0
One or more components selected from the group consisting of 001 to 0.1% by weight must be regulated so as to contain 0.0001 to 0.4% by weight in total.

(6) Limitation of Bi, As, Sb, and S Content These elements are harmful impurities that degrade hot workability. If these elements are contained outside the range of the present invention, cracks of the ingot occur during hot rolling, and it becomes difficult to produce a sheet material. Therefore, individually, Bi: 0.003 wt% or less, As: 0.003 wt% or less, Sb: 0.0
03% by weight or less, S: regulated to 0.003% by weight or less,
In addition, it is regulated so that the total content is not more than 0.005% by weight.

(7) Restriction of Fe and Ni Content The alloy of the present invention has a feature that it can exhibit excellent characteristics even when it is manufactured in the same process as phosphor bronze which has been frequently used. Of course, the same applies when an appropriate amount of Fe or Ni is added, and the existing production process and production equipment can be used as they are. When one or both of Fe and Ni are added, solid solution strengthening and, in particular, forming an intermetallic compound with P remaining as a deoxidizing agent to form Fe-P or Ni-
Precipitation of the P compound improves strength, conductivity, and heat resistance. However, in order to obtain an effective effect of improving strength, conductivity, and heat resistance, each element alone or in a total of 0.1% is used.
It is necessary to add 0005% by weight or more.

On the other hand, the upper limit of the amount of addition of Fe and Ni is determined by the relative magnetic permeability of the alloy. That is, for an electric / electronic component that inputs / outputs or amplifies an electric signal with high fidelity, if the relative magnetic permeability of the component becomes large, the signal waveform may be distorted or distorted. Since Fe and Ni increase the relative magnetic permeability when added to a copper alloy, it is necessary to regulate the upper limits of the amounts of these added. In a copper alloy for electric / electronic parts, the preferable relative magnetic permeability is 1.0002 or less. However, if Fe and Ni alone are 1.0% by weight or less, the magnetic permeability is 1. 0001 or less, Fe and N
Even when i is co-added at 2.0% by weight or less, the magnetic permeability can be suppressed to 1.0002 or less. Note that Fe and Ni
The desirable range of the content is 0.0005 to
0.5% by weight, and when both are added, the total is 0.0
005 to 0.8% by weight.

(8) Restriction of H and O Content The alloy of the present invention also absorbs gas elements H and O at the stage of melting. Since the solubility of these H and O during solidification decreases, if the O content is not regulated to 50 ppm or less and the H content is regulated to 20 ppm or less, air bubbles are easily formed in the ingot. If these air bubbles remain, the ingot cracks during hot working and blisters during the annealing process are liable to occur. Therefore, the O content is regulated to 50 ppm or less and the H content is regulated to 20 ppm or less.

(9) Restriction of crystal grain size Controlling the crystal grain size to an appropriate size in a copper alloy has an effect of improving mechanical properties and chemical properties such as corrosion resistance. In general, the larger the crystal grain size,
The drawability improves and the anisotropy of the mechanical properties disappears, but the strength itself decreases as the crystal grain size increases. In addition, copper alloys for electric and electronic parts, which are applications of the alloy of the present invention, are often subjected to complicated bending. For this reason, if the crystal grain size is too large, the bent portion has a rough surface called orange peel and a crack caused by the skin. And so on.
This rough surface is caused by a difference in strain due to deformation between crystal grains and at grain boundaries, and control of the crystal grain size is indispensable in order not to degrade the product value. Further, the susceptibility to stress corrosion cracking increases as the crystal grain size increases, and the corrosion resistance decreases. Therefore, in the alloy of the present invention, it is necessary to specify the upper limit of the crystal grain size.

In the production process of the copper alloy according to the present invention, the cast solidified structure in which the solute is segregated microscopically is homogenized by homogenizing annealing or hot rolling, and then subjected to cold rolling to obtain a hardened material having a rolled fiber structure. The material is processed to a state of no elongation.After that, by annealing at an appropriate temperature lower than the homogenizing annealing generally called finish annealing, the internal stress of the material is dissipated and the fibrous structure disappears, and the recrystallized structure Is performed so as to form. After this, further finish rolling is performed, so that generally 1 / 4H, 1 / 2H, H, EH
Although it is finished to a predetermined temper called as such, the recrystallization structure with polygonal grains by this last rolling step, the crystal shape becomes a shape elongated in the rolling parallel direction, that is, the material longitudinal direction . Therefore, the crystal grain size needs to be defined in both the rolling parallel direction and the vertical direction.

In the copper alloy according to the present invention, when the crystal grain size at the final plate thickness is measured by a cutting method specified in JIS 0501, both the cross section parallel to and perpendicular to the rolling direction of the material and both in the plate thickness direction are from 20 μm. If it is small, the occurrence of roughening of the bent portion and the increase in stress corrosion cracking susceptibility as described above do not occur. However, if it is outside this range, the stress corrosion cracking susceptibility increases and poses a practical problem. Further, the surface of the bent portion is roughened, and the product value is remarkably deteriorated as a material for electric / electronic parts.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION In producing a copper alloy according to the present invention,
It is possible to apply the same manufacturing process as conventional phosphor bronze, that is, C5111, C5102, C5191, C5212 specified in JIS 3110, and C5210 specified in JIS 3130. Specifically, this is a step of hot rolling a slab produced by continuous casting, and thereafter combining cold rolling and annealing to form a thin plate having a predetermined thickness. In addition to this, it is also possible to turn a thin slab of 10 to 30 mm produced by horizontal continuous casting without employing hot rolling into a thin plate having a predetermined thickness in a process in which heat treatment and cold rolling are combined. .

The hot workability and the cold workability of the copper alloy according to the present invention are good, and there is no problem such as cracking in the steps of hot rolling, cold rolling and the like. Either a batch method or a continuous method may be used for the intermediate annealing of the present alloy. Intermediate annealing conditions are 350 to 600 ° C x 5 when using a batch furnace.
Holding for 5 minutes to 5 hours (material arrival temperature x holding time after arrival), 400 to 800 ° C x 10 to 30 when using a continuous annealing furnace
The object can be achieved by holding for 0 seconds (material arrival temperature × retention time after arrival). In addition, Ni, Fe,
When Cr, Mn, and Si are added, Ni-P, Fe-P,
Mn-P, Ni-Si, Cr, etc. precipitate. In order to sufficiently precipitate these compounds and elements, it is desirable to perform annealing in a batch annealing furnace. When the addition amount of these elements is small or when precipitation is not necessary, continuous annealing may be performed.

Further, although the strength of the material is improved by the final rolling ratio after the finish annealing, the ductility is reduced. For this reason, the working ratio is determined by the balance between the required strength and elongation, but usually a working ratio of 5 to 90% is adopted. After the final rolling or after forming into an electric / electronic part, heat treatment (low-temperature annealing) for the purpose of improving the spring limit value and recovering ductility may be further performed. As this heat treatment method, either a batch method or a continuous method may be used, and the desired final characteristics can be obtained.

The reason why the low temperature annealing improves the spring limit value and recovers the ductility, and the reason why the low temperature annealing is performed at a temperature of 200 to 600 ° C. for 10 seconds to 2 hours in the present invention will be described below. I do. Applying a repetitive external force such as rolling to the metal or an external force for plastic working such as press forming can only exceed the friction in the sliding surface of the crystal grains during the movement of the metal polycrystal due to this external force. Equivalent to supplying work. The energy of this work is irreversibly turned into heat and consumed. This energy wasting mechanism is internal friction existing in the crystal grains, and the internal friction further increases when cold working is performed because the sliding surface increases. Therefore, in the state of cold working, the force for restoring the original force when the applied external force is removed, that is, the elasticity, is consumed by an energy proportional to the magnitude of the internal friction. That is, the elasticity is lost accordingly.

In the electric and electronic parts such as terminals, connectors and relays according to the present invention, high elasticity is often used as a property of returning to the original state after removing external force, that is, a spring property. When so-called low-temperature annealing is performed at a temperature lower than the recrystallization temperature of the metal material, the internal friction is reduced, so that the elasticity is recovered by that much and a large spring property can be imparted. After cold working the copper alloy according to the present invention or forming it into an electric / electronic part such as a terminal,
When heating is performed at a temperature of ６００600 ° C. for 10 seconds to 2 hours, it is possible to provide a spring limit value that is 1.1 times or more the spring limit value before heating. However, if the annealing conditions are out of this range, the spring limit value is conversely reduced, and the product value is remarkably deteriorated as a material for electric and electronic parts such as terminals, connectors, and relays.

[0028]

Next, examples of the copper alloy for electric / electronic parts according to the present invention will be described. (Example 1) In this example, the feasibility of manufacturing a plate material is demonstrated. The copper alloys having the components and component ratios shown in Tables 1 to 4 were melted under a charcoal coating in the air in a kryptor furnace, cast and cast to a thickness of 50 mm, a width of 70 mm, and a length of 200 m.
m was produced. The surface of the ingot was removed by face milling, hot-rolled at 700 to 850 ° C.
mm hot rolled material was produced. The surface of this hot rolled material is 1 mm each
The oxide film was removed by chamfering, and then cold rolling and heat treatment were performed. However, the processes after the cold rolling were stopped for those having cracks during hot rolling. The subsequent steps were as follows. If cracks occurred in the sheet material, the production was stopped at that stage. That is, this hot-rolled material is used in a plate thickness of 3.
Cold-rolled to 2 mm, rough annealing was performed in an electric furnace at a temperature of 500 ° C. for 2 hours, and after removing the oxide scale of the sheet material, the sheet material was cold-rolled to a thickness of 1.2 mm.
Cold-rolled to 450 ° C.
For 2 hours. Next, in order to secure a processing rate (in the range of approximately 20 to 70% depending on each composition) necessary for obtaining a predetermined temper for a sheet thickness of 0.25 mm in the final product, intermediate annealing from which oxide scale has been removed. Subsequent plate material is 0.9 mm to 0.2 mm.
Cold rolling is performed to 3 mm according to each composition, and finish annealing is performed. This finish annealing is an important step for determining the crystal grain size in the final product, and is performed for 2 hours at 400 ° C. to 490 ° C. for the alloys of the present invention and the comparative example. After removing the oxide scale by pickling this plate material, it is further subjected to finish rolling to produce a sample having a thickness of 0.25 mm.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

As a result, all alloys whose compositions were within the range specified in the present invention were able to produce plate materials, but the comparative alloys in which any component was not in the range specified in the present invention were:
There was a problem as shown in Table 5, and the production was abandoned halfway.

[0034]

[Table 5]

Example 2 In this example, the solder wettability, the adhesion of the molten solder and Sn, the solder plating and the S
Adhesion of n-plating, relative permeability, pickling properties, Sn plating whisker suppression effect, reduction of die wear during press punching and press forming, or reduction of wear of mating material when used as a sliding mechanism component The reduction effect is demonstrated. The same steps as in Example 1 were performed on the copper alloy sheet having a thickness of 0.25 mm (the alloy of the present invention in Tables 1 and 2) produced in Example 1 and the copper alloy having the components and component ratios shown in Table 6. Using a copper alloy sheet having a thickness of 0.25 mm produced as a sample, various characteristics were tested in the following manner. Table 7-
It is shown in Table 9.

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

[Table 8]

[0039]

[Table 9]

Measurement of Tensile Strength, Elongation, and Conductivity Tensile strength and elongation were measured by preparing a tensile test specimen specified by JIS No. 13B by machining and using a universal testing machine UH-10B manufactured by Shimadzu Corporation. Tests were performed and measured. The electric conductivity was measured using a double bridge 5752 manufactured by Yokogawa Electric Corporation in accordance with the non-ferrous metal material electric conductivity measurement method specified in JIS H0505. -Solder wettability The solder wettability was evaluated by immersing a material coated with a non-active flux in advance in a 245 ° C 60Sn / 40Pb solder bath for 5 seconds.
After immersion, evaluation was made based on the ratio of the area of the portion actually wet with the solder. As shown in Table 8, the alloy of the present invention was wet by 95% or more of the solder, and the solder wettability was good.

Regarding the presence / absence of solder whitening and solder adhesion The presence / absence of solder whitening and solder adhesion are as follows.
A material coated with an inert flux beforehand is immersed in a 0Sn / 40Pb solder bath for 5 seconds and soldered, and then heated in an oven at 150 ° C. for up to 1000 hours, and its appearance is soldered before heating. The presence or absence of whitening was visually checked in comparison with the above. After that, 1 mm at 2 mmR
After bending by 80 °, the plate was bent back and the presence or absence of peeling of the solder from the material at that time was visually evaluated. As shown in Table 8, the alloy of the present invention did not cause solder whitening and solder peeling even after heating at 150 ° C. for 1000 hours, and the solder whitening resistance and solder adhesion were good.

Regarding the presence / absence of whitening of solder plating and adhesion of solder plating The presence / absence of whitening of solder plating and adhesion of solder plating are as follows.
90S comprising 193 g / l stannous alkanolsulfonate, 3.5 g / l lead alkanolsulfonate, 100 g / l alkanesulfonic acid, and 30 cc / l additive
Current density 3 in n / 10Pb solder plating bath (40 ° C)
90Sn / 10P with plating thickness of 10μm at A / dm2
b After the solder plating, heating was performed in an oven at 150 ° C. for a maximum of 1000 hours, and the appearance was compared with a solder-plated test material before heating to visually check for whitening. Further, after bending at 180 ° at 2 mmR, the sheet was bent back to a flat plate, and at that time, the presence or absence of peeling of the solder plating from the material was visually evaluated. As shown in Table 8, the alloy of the present invention was 150
Even after heating at 1000C for 1000 hours, whitening of the solder plating and peeling of the solder plating did not occur, and the whitening resistance and the adhesion of the solder plating were good.

Sn plating adhesion Sn plating adhesion was 40 g / l of stannous sulfate and 10 g of sulfuric acid.
0 g / l, cresolsulfonic acid 30 g / l, formalin 5 ml / l, dispersant 20 g / l, brightener 10 ml /
current density in a Sn plating bath (20 ° C.)
After applying Sn plating with a plating thickness of 1.5 μm at 5 A / dm ^2, heating was performed in an oven at 150 ° C. for up to 1000 hours, and then bent at 180 ° at 2 mmR, and then bent back to a flat plate. Was visually evaluated by the presence or absence of peeling of the Sn plating from. As shown in Table 8, the alloy of the present invention did not peel off the Sn plating even after heating at 150 ° C. for 1000 hours, and the Sn plating adhesion was good.

Regarding the occurrence of whisker of Sn plating The presence or absence of whisker of Sn plating is determined by determining whether stannous sulfate is 40 g /
l, sulfuric acid 100g / l, cresolsulfonic acid 30g
/ L, formalin 5ml / l, dispersant 20g / lit,
In Sn plating bath consisting of brightener 10ml / l (20 ° C)
At a current density of 2.5 A / dm ^{2 and a} plating thickness of 10 μm.
After applying the Sn plating, the test material subjected to the Sn plating was allowed to stand in a room at room temperature for one year, and then the surface of the test material was observed and confirmed with a scanning electron microscope and an optical microscope. As shown in Table 8, the alloy of the present invention still has a whisker of 5 μm after one year.
It grows only to the following, and the growth of the Sn plating whisker is suppressed.

Regarding the pickling property The pickling property was evaluated by etching each material for 30 seconds with an etching solution of 30% by weight sulfuric acid and 3% by weight of hydrogen peroxide at 40 ° C., and adjusting the surface of each material. 40 ° C. consisting of 20% by weight of ammonium hydrofluoride and 20% by weight of sulfuric acid
The material was immersed in an acid washing solution for 20 seconds to remove oxides on the surface, and used as an initial state. These materials are used as a combustion gas of a mixture of air and butane gas, that is, 10 to 20% by volume of carbon dioxide gas, 3% by volume or less of carbon monoxide gas, 0.2% by volume or less of oxygen gas, the balance of nitrogen gas and dew point of 5 degrees Celsius.
The material surface was oxidized by heating at 450 ° C. for 2 hours in a heat-generating atmosphere gas composed of water. 25 of these materials
Immersed in a 20% by weight aqueous sulfuric acid solution at 10 ° C. for 10 seconds, washed with water and dried, and the surface of the material was analyzed with an X-ray photoelectron analyzer (ESCA).
LAB-210D, manufactured by VG SCIENTIFIC) was used to analyze Cu2p, Sn3d, Zn2p, and P2p spectra to confirm the presence or absence of oxides of each element.
As shown in Table 9, the alloy of the present invention can remove oxides of the material by pickling using only sulfuric acid.

Measurement of relative magnetic permeability The relative magnetic permeability was measured using a vibrating sample magnetometer manufactured by Riken Denshi Co., Ltd. As shown in Table 9, the alloy of the present invention has a relative magnetic permeability of not more than 1.0002. -Whether or not dezincification occurs during pickling. Whether or not dezincification occurs during pickling is determined by immersing the material in a 40 ° C pickling solution consisting of 5% by weight ammonium hydrofluoride and 20% by weight sulfuric acid for 20 seconds. The cross section of the material after
Observation was performed with an optical microscope at a magnification of × to determine whether a porous portion was formed due to dezincification corrosion.
As shown in Table 9, no dezincification corrosion occurred during pickling in the alloy of the present invention.

Regarding the mold wear test The mold wear test was evaluated using a tool wear resistance test method as shown in FIG. In this method, a steel ball 2 is fixed to the tip of a ball holder 1, and is pressed against a specimen 3 sent at a constant speed on a table 4 while rotating the ball 2 at a turning radius of 6.2 mm. It measures the weight. Table 10 shows the test conditions.

[0048]

[Table 10]

As shown in FIG. 2 (a), the wear weight of the steel ball is measured by measuring the radius c of the wear portion, and the volume V of the wear portion (FIG. 2 (b)) is calculated by the following equation. And multiplied by the specific gravity (= 7.9). V = πh ² (r−h / 3)... H = r− (r ² −c ² ) ^1/2 r: radius of a steel ball ball This test was performed when a steel ball was rubbed over a length of 100 m. However, as shown in Table 9, the alloy of the present invention has a maximum wear loss of 2.1 μg.

Example 3 In this example, the improvement of the elongation characteristics and the improvement of the bending workability will be demonstrated. Copper alloys having the components and component ratios shown in Table 11, that is, the alloy No. of the present invention. 30 and no. 31 and Z respectively
Comparative Example Alloy No. n in which only an amount less than the range of the present invention was added. 32 and 33 were subjected to the same steps as in Example 1 and a 0.25 mm-thick copper alloy sheet was used as a sample to test various characteristics in the following manner. Table 12 shows the results. The finishing rolling rate here is
Alloys of the present invention and comparative alloys (No. 30 and No. 32, N
o. 31 and No. 31. 33) are adjusted so as to have the same tensile strength as much as possible in the rolling parallel direction.

[0051]

[Table 11]

[0052]

[Table 12]

Tensile strength, elongation and bending workability Tensile strength and elongation were measured by the methods described above. Further, a stress-strain curve at that time was plotted with an XY recorder UA-6122 manufactured by Shimadzu Corporation. The bending limit is
Using a B-type bending jig specified in the CESM0002 metal material W bending test method, a test material processed to a width of 10 mm and a length of 35 mm is sandwiched, and a universal testing machine RH-3 manufactured by Shimadzu Corporation.
It measured by performing bending with a load of 1 ton using 0. The discrimination was made by reducing the bending radius of the bending jig, and using a magnifying glass to determine whether or not the bent portion of the test material exhibited cracks or the like. Further, if the bending jig has a good bending property even when the bending radius of the bending jig becomes zero, the test material is bent into a W shape using the bending jig having the bending radius of zero, and then further bent. The test piece is a universal testing machine RH made by Shimadzu Corporation.
Completely crushing with a load of 1 ton using -30,
A so-called close-contact bending was performed, and the bending portion was inspected with a loupe to examine the bending limit. As shown in Table 12, the alloy of the present invention requires a lower finish rolling rate to obtain the same tensile strength in the rolling parallel direction as compared with the comparative example alloy,
The elongation in the direction parallel to the rolling direction and the direction perpendicular to the rolling direction are also larger than those of the comparative example alloy. Also, the bending workability limit of the alloy of the present invention is better.

Example 4 This example demonstrates the specified range of crystal grain size. For the copper alloy having the components and component ratios shown in Table 13, 1.2 m
m of cold-rolled material was prepared and annealed at 450 ° C. for 2 hours. Thereafter, cold rolling and finish annealing were performed on each sheet material in the following steps to produce a copper alloy sheet material having a thickness of 0.25 mm. No. No. 34: cold rolling to 0.321 mm → annealing at 400 ° C for 2 hours → cold rolling to 0.25 mm (working ratio 22%) No. 35: cold rolling to 0.333 mm → annealing at 425 ° C × 2 hours → cold rolling to 0.25 mm (working rate 25%) No. 36: cold rolling to 0.362 mm → annealing at 470 ° C × 2 hours → cold rolling to 0.25 mm (working ratio 31%) 37: cold rolling to 0.417 mm → annealing at 490 ° C × 2 hours → cold rolling to 0.25 mm (working rate: 40%) Thus, each sample has a tensile strength in a direction parallel to the rolling direction at a thickness of 0.25 mm. The final processing rate was changed to 22 to 40% so that the values were almost the same. In addition, recrystallization was performed by finish annealing to adjust the crystal grain size. Although the recrystallized grains are elongated in the rolling direction by the subsequent finish rolling, the crystal grain size could be easily measured by the method described later. Using this as a sample, various characteristics were tested as follows. Table 14 shows the results.

[0055]

[Table 13]

[0056]

[Table 14]

Measurement of crystal grain size The sample material was embedded in a polishing resin so that a cross section in a direction parallel to the rolling direction of the material and a cross section in a direction perpendicular to the rolling direction could be observed and mirror-polished. After etching using an aqueous iron solution so that crystal grains appeared clearly, the crystal grain size was measured in the thickness direction by a cutting method specified by JIS H501.

Tensile strength, elongation, and appearance of bent portion The tensile strength and elongation were measured by the methods described above. The appearance of the bending test section is 10 mm wide and 35 m long using a B-type bending jig specified in the CESM0002 Metallic Material W Bending Test Method.
m sample material, Shimadzu Universal Testing Machine RH-3
After performing a bending process with a bending radius of 0 mm under a load of 1 ton using 0, when observing the outside of the bent portion with an Olympus SZH type optical stereo microscope (magnification: 40 times), the crystal grain size that can be visually detected is It was determined whether or not skin roughness, which was represented by a swell of several times, occurred. As shown in Table 14, even if the tensile strengths are substantially the same, those having a crystal grain size within the scope of the present invention in a cross section in a direction parallel to the rolling direction and in a direction perpendicular to the rolling direction are
The appearance of the bent part has not deteriorated.

Stress Corrosion Cracking Stress corrosion cracking is described in Material Res
ear & Standards 1 (61) 108. H. The method of Thompson, that is, a test piece with a width of 12.7 mm and a length of 150 mm, drilled at both ends, was fixed in a loop with a copper wire, exposed to ammonia vapor for 100 hours, then untied and the distance of the test piece was measured. Then, the stress relaxation rate was obtained. Here, the stress relaxation rate is defined as the distance between both ends of the test piece before L1 is exposed to ammonia,
When L2 is the distance after exposure, it is calculated by the following equation. Stress relaxation rate (%) = ((L1−L2) / L1) × 100 (%) ··· The ammonia vapor atmosphere is created by maintaining a 14% aqueous ammonia solution in a closed container at 40 ° C. Table 1
As shown in FIG. 4, even if the tensile strength is the same, the crystal grain size within the range of the present invention in the cross section in the direction parallel to the rolling direction and in the direction perpendicular to the rolling direction is the stress relaxation after exposure to ammonia vapor for 100 hours. The rate is kept within 30%.

Example 5 This example demonstrates the specified range of low-temperature annealing conditions. A copper alloy sheet having a thickness of 0.25 mm produced by performing the same steps as in Example 1 on copper alloys having the components and component ratios shown in Table 15 was used as a sample. Further, test pieces were cut out from these samples, and the temperature was measured. The heat treatment (low-temperature annealing) was carried out by using an oil bath, a saltpet furnace, an oven, a Kanthal furnace, or the like depending on the time. Various properties were tested as follows, and the results are shown in Table 16.

[0061]

[Table 15]

[0062]

[Table 16]

Regarding the spring limit value The spring limit value (Kb _0.1 ) is determined for each sample before and after annealing in accordance with JIS 3130 by machining a test material to predetermined dimensions and then using a spring manufactured by Akashi Seisakusho. It was measured at room temperature by a moment type test using a limit value measuring device APT. The tensile strength and elongation were measured on the sample after annealing by the method described above. As shown in Table 16, after finish rolling,
When low-temperature annealing is performed within the condition range defined in the present invention, a spring limit value that is 1.1 times or more as large as the spring limit value before annealing can be provided. It is not enough or conversely decreases, and the product value is remarkably deteriorated as a material for electric / electronic parts such as terminals, connectors and relays.

[0064]

Industrial Applicability The copper alloy for electric / electronic parts according to the present invention has properties that are far superior to the mechanical properties which are the advantages of phosphor bronze, and has better solder wettability than phosphor bronze.
Has adhesion of solder, solder plating and Sn plating,
Further, pickling is much easier than phosphor bronze,
The growth of n-plated whiskers can also be suppressed. Moreover, the effect of suppressing mold wear is far superior to that of phosphor bronze.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a tool wear resistance test method according to an example of the present invention.

FIG. 2 is an explanatory diagram of a method for measuring a wear amount of a steel ball ball used in the example.

[Explanation of symbols]

 2 Steel ball balls

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 630 C22F 1/00 630D 661 661A 685 685Z 686 686 686A 691 691B 691C 694 694Z

Claims (5)

[Claims] 1. Sn: 0.2 to 12% by weight, Zn: 0.1% by weight.
1 to 12% by weight, P: 0.001 to 0.4% by weight, P
b: 0.0005 to 0.015% by weight so that the Zn / Sn ratio is 1 or less, and Cr: 0.0001
0.1% by weight, Mn: 0.0001-0.1% by weight,
Al: 0.0001 to 0.1% by weight, Si: 0.000
A total of 0.0001 to 0.4% by weight of one or more components selected from the group consisting of 1 to 0.1% by weight;
i, As, Sb, and S are individually 0.003% by weight or less,
A copper alloy for electric / electronic parts, characterized in that the total amount is 0.005% by weight or less, and the balance consists of Cu and unavoidable impurities. 2. The method according to claim 1, wherein one of Fe and Ni is added to 0.1.
0005-1.0% by weight or both in a total of 0.0
The copper alloy for electric / electronic parts according to claim 1, wherein the copper alloy is contained in an amount of 005 to 2.0% by weight. 3. The copper alloy for electric and electronic parts according to claim 1, wherein the O content is 50 ppm or less and the H content is 20 ppm or less. 4. The copper for electric / electronic parts according to claim 1, wherein the crystal grain size in the thickness direction in a cross section parallel or perpendicular to the rolling direction is less than 20 μm. alloy. 5. A copper alloy having a component composition according to claim 1 after final cold working or after forming into an electric / electronic component, at a temperature of 200 to 600 ° C. for 10 seconds to 2 hours.
The electric / electronic device according to any one of claims 1 to 4, wherein by heating for a time, the spring limit value is improved to a value that is 1.1 times or more the spring limit value before heating.
Manufacturing method of copper alloy for electronic parts.