JPS6338543A - Copper alloy for electronic appliance and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a Cu alloy for electrical appliances having superior mechanical strength, electrical conductivity, heat conductivity, solderability, platability and corrosion resistance by subjecting a Cu alloy ingot contg. specified very small amounts of Zr, Cr, Zn and other elements and having relatively high O2, P and S contents to hot working, soln. heat treatment and cold working under specified conditions. CONSTITUTION:A Cu alloy ingot contg., by weight, 0.03-0.3% Zr, 0.05-0.5% Cr, 0.01-0.5% Zn, 0.0005-0.05% at least one among Mg, Ca and a rare earth element, <30ppm O2, <30ppm P and <10ppm S or further contg. <=0.5% in total of two or more among Fe, Ti, Y, In, Si, Ag, Mn, Hf, Ni, Sn, Co, Sb, Bi, Be, Li, B and Ba is hot worked, coldworked and subjected to soln. heat treatment by heating to 900-1,030 deg.C rapid cooling at >=30 deg.C/sec cooling rate. It is further cold worked at <5% working rate, annealed at 300-850 deg.C and cold worked again at >=10% working rate. The finish working rate is regulated to <50% and the diameter of precipitated Cr and Zr is restricted to <=10mu.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a copper alloy for electrical equipment and a method for producing the same.
It has improved plating properties, corrosion resistance, etc.

(Prior art) Electronic equipment, such as semiconductor lead frames, connectors,
Phosphor bronze (Cu
-3n alloy), brass (Cu-2n alloy), nickel silver (C
u-N i -Zn alloy) etc. are generally used. Of these, brass and nickel silver have a fatal defect called stress corrosion cracking, so they are not suitable for applications subject to large mechanical stress. Further, phosphor bronze is widely used due to its excellent strength and moldability, but SR+, which has low conductivity and is expensive, is often used. Furthermore, it is easy to cause peeling of soldering and 3N and 3N alloy plating, and is also susceptible to stress corrosion cracking, although this is not the case with brass and nickel silver.

For this reason, CLJ-Fe alloys are used in some applications. For example, 0194(Cu-2,3wt%Fe
-0,12wt% Zr1-P alloy) (hereinafter wt% is abbreviated as %) YaC195 (CLl-1,5%Fe-0,8%C
O-0,6%5RL-P alloy) does not have the strength of 6%5N phosphor bronze, but it has 2 to 3 times the conductivity and is not susceptible to stress corrosion cracking. However, not only is the workability inferior, but also the soldering properties are insufficient.

(Problems to be solved by the invention) In recent years, as electronic devices have become smaller, more highly integrated, and more sophisticated,
There is a need for high-performance CU gold alloys that can meet strong demands for reliability and economy. Such alloys are required to have the following properties.

(1) Excellent strength and electrical conductivity (thermal conductivity).

(2) Good moldability.

(3) Corrosion resistance, ie, no susceptibility to stress corrosion cracking.

(4) Soldering is based on properties and plating properties, that is, solder joint strength and 3N
, 3N alloy plating has high adhesion over a long period of time.

(Means for Solving the Problems) In view of this, the present invention is a steel for electronic devices that has excellent mechanical strength, electrical and thermal conductivity, and has improved solderability, plating properties, and corrosion resistance. The alloy and its manufacturing method were developed.

That is, one of the alloys of the present invention contains 0.03 to 0.3% Zr and 0
, r0.05~0.5%, Zn0.01~0.5%
, M.Q.

Contains 0.0005 to 0.05% of at least one of Ca and rare earths (RE), and has an α content of 30p.
pm or less, P content 30 ppm or less, S content io
ppm or less, the precipitate particle size is limited to 10 μ or less, and the remaining C
It is characterized by consisting of u and unavoidable impurities.

Another alloy of the present invention contains 0.03 to 0.3% Zr.
, Cr 0.05-0.5%, Zn 0.01-0.5%
, Mg, Ca, and at least one of rare earths (RE)
Species or more 0. Contains ~0.05% of F
e, Ti, Y, In, Si, Ag, Mn.

Hf, Ni, Sn, C0. sb, B i, Be.

Contains at least two of Li, B, and Ba at 0.5% or less, α content is 30 ppm or less, and P content is 30 ppm or less.
ppm or less, S content less than lhpm, precipitate particle size 1
It is characterized in that it is limited to 0μ or less, and the remainder consists of Cu and unavoidable impurities.

In addition, the production method of the present invention has Zr0.03 to 0.3%, Cr0
．． 05-0.5%, Z n0.01-0.5%, MO.

Contains 0.0005 to 0.05% of at least one of Ca and rare earths (RE), or contains Fe
, Ti, Y, In, Si, AQ, Mn.

Hf, Ni, Sn, G0. Sb, B i, Be.

Contain 0.5% or less of at least two of Li, B, and Ba, limit the α content to 30 ppm or less, the P content to 30 ppm or less, and the S content to 10 ppm or less, and the remainder is CLJ and unavoidable. After hot working and cold working a CU alloy ingot consisting of impurities, it was heated to 900-1030℃
After holding for 5-1800 seconds at the actual temperature of 300-8
Annealing at 50°C for 10 seconds to 12 hours and cold working at a working rate of 10% or more are repeated one or more times, and finally finish processing is performed at a working rate of 50% or less to reduce the precipitate particle size to 10 μ or less, preferably The thickness shall be 5μ or less.

[Effect]

The alloy of the present invention is an alloy in which Cr and Zr components are homogeneously precipitated and dispersed, and exhibits predetermined characteristics by synergistically combining the effects of both.

Mg, Ca, and RE all act effectively to homogenize the precipitation and dispersion of Zr and Cr, and have a particularly strong effect on Cr. The effects of these components are practically effective within the composition range of the alloy of the present invention; below the lower limit, no effect can be obtained, and above the upper limit, manufacturing defects and a decrease in electrical conductivity occur. In particular, excessive amounts of Cr and Zr tend to form coarse precipitated grains, which have a detrimental effect on workability, plating performance, soldering properties, etc. However, Cr0.
15-0.35%, Zr0.1-0.2%, MQ, Ca
The required properties can sometimes be maximized by adding at least one type of RE, Shirakawa, in an amount of 0.005 to 0.02%.

Zn has the effect of suppressing the coarse precipitation of Cr and the deterioration of the adhesion strength of soldering and plating, and is particularly effective within the composition range of the present alloy.
．． It works most effectively when it is set at 0.05 to 0.2%. However, if the content is less than the lower limit specified by the present invention, the effect will be weak, and if it exceeds the upper limit, moldability will deteriorate.

Fe, Ti, Y, In, Si, /'l, Mn.

Hf, Ni, Sn, G0. sb, B i, Be.

Li, B, and Ba (hereinafter abbreviated as subcomponents) suppress crystal coarsening during solution treatment, but when contained alone, they impair conductivity, plating properties, and soldering properties. Since the content is limited due to the characteristics and manufacturing aspects, and the effect is insufficient, at least two or more types are added in combination.

By adding these subcomponents in combination, they have the function of suppressing crystal coarsening without deteriorating the above-mentioned properties, and further reducing the sensitivity of the precipitation action of Cr and Zr to time. In particular, it is most effective at 0,005 to 0.3%. However, if the upper limit specified by the present invention is exceeded, not only the conductivity, plating properties, and soldering properties will deteriorate, but also
hinders manufacturability.

(3) is harmful to the uniform precipitation and dispersion of the components of the alloy of the present invention, tends to produce coarse precipitate grains, and not only inhibits the improvement of strength;
Plating and soldering deteriorate the properties and further deteriorate the molding processability, which is particularly harmful in practice for precision processed parts required for electronic devices, so the content should be reduced to 30 ppm or less, preferably 5 ppm or less. restricted. If P is included in excess, it will significantly impair the high conductivity that characterizes the alloy of the present invention, and will also concentrate at the interface with solder, worsening soldering properties. restricted. In addition, since S aggregates at grain boundaries and final solidification areas and greatly deteriorates hot rolling properties,
It is preferably limited to 5 ppm or less.

The properties of the alloy of the present invention, such as strength, can be optimized particularly by the above manufacturing method. However, the alloy ingot is 900 ~
Solution heat treatment by heating to 1030°C and then quenching is not sufficient solution treatment even if it is below 900°C, or even if heated and held at a temperature exceeding 1030°C and then rapidly cooled, it becomes coarse crystal grains and is molded. This is because it deteriorates workability, especially bending formability, and also causes grain boundary precipitation, resulting in deterioration of properties. Therefore, it is preferable that the temperature is 930 to 980 °C for products without added subcomponents, and 930 to 980°C for products with addition of subcomponents. Solution treatment is preferably carried out at 930 to 1010°C. Further, the reason why the holding time was limited to 5 to 1800 seconds is because if it is less than 5 seconds, no solution will be obtained, and if it exceeds 1800 seconds, no effect will be observed.

Next, after cold working by 5% or more after solution treatment,
Annealing at 300-850℃ for 10 seconds to 12 hours and 10%
The reason why the above cold working is performed at least once is to achieve homogeneous precipitation, and under conditions outside the range, there may be no precipitation, coarse precipitates may occur due to over-aging, or the final result may not be satisfied. characteristics cannot be obtained.Also, the final finishing rate is 5
The reason why the content is limited to 0% or less is that if processed beyond this value, the bending formability will deteriorate rapidly, making the copper alloy unsuitable for use in electronic devices.

The alloy of the present invention is heated at 200 to 500°C after the final finishing process.
By combining temper annealing, tension leveler, etc., even better properties can be obtained.

(Example) An ingot with the composition shown in Table 1 (width: 40 mm, thickness: 40 m, length: 300 m) was externally milled, heated to 880°C, held for 15 minutes, and then hot rolled. The thickness was 100 M. This was then cold rolled to a thickness of 1.2 #, and then heated to 950°C in a non-oxidizing atmosphere using a continuous quenching furnace.
Solution treatment was carried out under conditions of holding for 100 seconds. In addition, cooling was quickly performed by spraying water onto the treated material.

After that, it was cold rolled to 0.0B and then aged (45
0°C for 1 hour), then the thickness was 0.33. After rolling into
Aging treatment was performed at 450℃ for 1 hour, and after that, the processing rate was 20%.
The final processing was carried out to create a tentative finish with a thickness of 0.25 mm.

After tempering and tempering these at 300'C for 30 minutes, samples were cut out and examined for precipitate particle size, tensile strength, electrical conductivity, bending formability, corrosion resistance, solderability, and plating performance. The results were compared to the conventional product C194 (Cu-2,3%Fe
-0,12% Zn-P alloy) and 6% phosphor bronze (CLI
-6%5n-P alloy) as shown in Table 2.

Bending formability is determined by performing a 90' V bending test with various tip radii (R), examining the cracking state of the bent part with a microscope, and calculating the ratio of the minimum radius (R) without microcracks to the plate thickness (1) (R/l). ) was sought. Corrosion resistance was determined by stress corrosion cracking (constant load method in 3vol% NH3 steam) according to JIS C8306. The load was 50% of the tensile strength. As for soldering, a lead wire was eutectic soldered to a 9InIn diameter portion, and the joint strength was determined by a pull test after aging at 150° C. for 600 hours. In addition, the plating property was 7.5 μm using a borofluoride bath.
It was plated to a thickness of , held at 105°C for 2000 hours, bent at 180°, and inspected with a microscope to see if the plating layer peeled off at the bent portion.

The comparative alloys Nα17 and Nα18 in Table 2 have the same composition as the invention alloy NQ3 in Table 1, but the solution treatment conditions for Nα17 were 1050°C and 100 seconds, and the final processing rate for Nα18 was 60%. That is.

As is clear from Table 7R1 and Table 2, the alloy N of the present invention
All α1 to α10 produced by the method of the present invention are the conventional product Nα19. It can be seen that each characteristic is far superior compared to Nα20.

On the other hand, even if the comparative alloy and the present invention alloy fall outside the composition range specified for the present invention alloy, if the comparative amount falls outside the conditions of the present invention production method, they will all be inferior in one or more of the respective properties.

That is, comparative alloy No. 0 with a high CLJ content. 11 and O2
Comparative alloy N013, which has a high content, has a large precipitate grain size and is inferior in bending formability, solder joint strength, and plating property, and Z
Comparative alloy Nα12, which does not contain n, has poor solder joint strength. Comparative alloy N0.14, which has a high P content, has a large precipitate grain size and is inferior in strength, electrical conductivity, bending formability, and solder joint strength, and comparative alloy N0.14, which has a high M(J1')Ca content
In No. 015, cracks occurred during hot rolling and further processing was impossible. Comparative alloy Nα16, which has many subcomponents, exhibits excellent strength but is inferior in electrical conductivity and bending formability. Furthermore, even if the composition is within the composition range of the alloy of the present invention, the comparative amount Nα17. Nα18 has poor bending formability and plating properties.

〔Effect of the invention〕

As described above, according to the present invention, strength, electrical/thermal conductivity, moldability, corrosion resistance, plating property, and soldering properties are as follows:
It is far superior to conventional copper alloys, and has significant industrial effects, such as being useful as a spring material for electronic devices, such as semiconductor lead frames and connectors/switches.

Claims (3)

[Claims] (1) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg, Ca
, at least one of the rare earths (RE).
．． 0005 to 0.05 wt%, limiting the O_2 content to 30 ppm or less, the P content to 30 ppm or less, the S content to 10 ppm or less, and the precipitate particle size to 10 μ or less,
Copper alloy for electronic devices consisting of Cu and unavoidable impurities. (2) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg, Ca
, at least one of the rare earths (RE).
．． 0005 to 0.05 wt%, and further contains Fe, Ti
, Y, In, Si, Ag, Mn, Hf, Ni, Sn, C
o, contains at least two or more of Sb, Bi, Be, Li, B, and Ba at 0.5 wt% or less, O_2 content is 30 ppm or less, P content is 30 ppm or less, S content is 10 ppm or less, Limiting the precipitate particle size to 10μ or less,
Copper alloy for electronic devices consisting of Cu and unavoidable impurities. (3) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg, Ca
, at least one of the rare earths (RE).
．． 0005 to 0.5 wt%, or in addition to Fe,
Ti, Y, In, Si, Ag, Mn, Hf, Ni, Sn
, Co, Sb, Bi, Be, Li, B, and Ba in an amount of 0.5 wt% or less, O_
2 content is limited to 30 ppm or less, P content is limited to 30 ppm or less, S content is limited to 10 ppm or less, and after hot working and cold working is performed on a Cu alloy ingot consisting of the remaining Cu and inevitable impurities, 5-1 at actual temperature of 900-1030℃
After holding for 800 seconds and solution treatment by rapidly cooling at a cooling rate of 30°C/second or more, cold working is performed at a processing rate of 5% or more, followed by annealing at 300 to 850°C for 10 seconds to 12 hours. and cold working at a processing rate of 10% or more is repeated one or more times, the final finishing rate is 50% or less, and the precipitate grain size is reduced to 10μ.
A method for producing a copper alloy for electronic devices, characterized by the following: