JP2521880B2 - Copper alloy for electronic and electrical equipment and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent practical properties such as strength, conductivity, plating property, solderability, etc., for electronic and electrical equipment, particularly for semiconductor lead materials, connectors, switches, contact springs for relays, terminals, etc. The present invention relates to a copper alloy and its manufacturing method.

[0002]

2. Description of the Related Art Cu alloys are frequently used for parts and members of electronic and electrical equipment. Recently, in addition to miniaturization, high density and high precision, economic efficiency is strongly desired. brass,
In place of phosphor bronze, higher performance and economic efficiency are required. For example, even phosphor bronze, which has far superior mechanical properties to brass, has a problem of reliability of universal solder joint in addition to stress corrosion cracking (SCC) susceptibility, which is universal for electronic and electrical applications. As the same kind of defect, when Sn or Sn-Pb alloy (solder) plating is used in place of the noble metal for the electrical contact or the connecting portion, the adhesiveness is lost with time, and the peeling phenomenon occurs like the solder joint portion. cause. This is a phenomenon caused by a diffusion reaction between Cu and Sn and progresses even at a low temperature of 100 ° C. or less, and therefore, JP-B-51-41222 and JP-A-49-10.
As illustrated in Japanese Patent No. 8562, extra steps such as pre-forming a thick Cu or Ni barrier layer by plating are required.

Therefore, in some cases, a Cu-Fe alloy such as C194 (2.3 wt% Fe, 0.12 wt% Zn,
0.03 wt% P, balance Cu (hereinafter wt% is abbreviated as%) and C195 (1.5% Fe, 0.6% Sn, 0.2)
% Co, 0.03% P, balance Cu), etc. are used. These alloys are those in which a large amount of Fe is deposited and dispersed in the form of a phosphide or a simple metal, and not only causes microcracks in precision bending, but also has the problem of poor reliability of the solder joint.

[0004]

Under such circumstances, there is a strong demand for improvement of the following defects and defects in Cu-Sn alloys which are excellent in mechanical strength and precision workability.

(1) To save expensive Sn and exhibit equivalent strength. (2) The strength and the electrical conductivity are in a contradictory relationship, but both should be compatible at a higher value. (3) Do not cause SCC. (4) The solder joint and the Sn, Sn-Pb alloy plating should not be peeled off with time. (5) The composition is advantageous in manufacturing and does not cause defects such as cracks in hot working. (6) Being manufactured by atmospheric melting casting that does not require special equipment.

[0006]

As a result of various studies in view of the above, the present invention has been developed as a contact spring for electronic and electrical equipment, particularly semiconductor lead materials, connectors, switches, relays, terminals, etc. This is a copper alloy that has excellent practical properties such as solderability and a manufacturing method thereof.

As the copper alloy of the present invention, Sn: 0.05-
2%, P: 0.005 to 0.1%, Mn: 0.03 to
2.0%, and further contains any one or more of Cr, Co, Ti, and Zr in a total amount of 0.05 to 1%, and the balance C.
It is characterized by comprising u.

Further, according to the manufacturing method of the present invention, Sn: 0.05 to 2
%, P: 0.005 to 0.1%, Mn: 0.03 to 2.
0%, and further contains any one or more of Cr, Co, Ti, and Zr 0.05 to 1% in total, and after hot working an alloy consisting of the balance Cu at 700 to 1050 ° C. ,
After cooling at least 400 ° C at a rate of 15 ° C / sec or more, and then performing cold working of 30% or more,
It is characterized in that heat treatment is performed at 400 to 650 ° C.

That is, the present invention is made of an alloy having the above composition. The ingot is hot worked at 700 to 1050 ° C., cooled to at least 400 ° C. at a rate of 15 ° C./sec or more, and then cooled to 30% or more. It is produced by subjecting it to interworking and then heat treatment at 400 to 650 ° C. Further, the alloy of the present invention can be improved in elongation and stress relaxation resistance without losing strength if it is subjected to low temperature annealing at 200 to 400 ° C. after being further processed into a desired size after the above heat treatment. And, especially in the case where conductivity and heat resistance are important, such as semiconductor lead materials and electric equipment, S
The n content is 0.1 to 2%.

[0010]

The alloy of the present invention is a Cu-Sn solid solution alloy in which precipitation of Cr, Co, Ti, and Zr is used in combination, and strength and conductivity can be improved for alloys having the same Sn content. Although it depends on the additive element and composition, it corresponds to approximately 1 to 2% of the Sn amount, which is economically advantageous. The additive element is a simple metal, a compound with P, particularly Zr is Cu ₃ Zr and Ti is Ti.
It becomes a minute precipitate as Sn, and SC of Cu-Sn alloy
The C sensitivity can be greatly improved and suppressed.

In the present invention, the concentration of P is reduced to 0.005 to 0.1%, which is lower than the P amount of ordinary phosphor bronze (0.1 to 0.25%), and Zn or Mn is used as a deoxidizing agent instead. It was done. The decrease in P is the main cause of cracking during hot working Cu-
It prevents the formation of a low melting point phase such as P, Cu-Sn-P, and Sn.
Greatly improves plating and solderability. That is, the peeled plating and the solder joints all show a black color, and concentrated P is detected in addition to Cu and Sn. This is because P in the phosphor bronze diffuses and concentrates in the ε phase on the phosphor bronze side among the intermetallic compounds of Cu and Sn (η ′ phase and ε phase) formed at the interface between plating or solder and phosphor bronze. By further embrittlement of the phase, the strength of the solder joint is reduced.

The present invention prevents the embrittlement phenomenon by suppressing P to 0.005 to 0.1%. The addition of Mn not only prevents the embrittlement phenomenon but also improves hot workability. It also improves mechanical properties. Although the mechanism of the action of Zn and Mn is unknown, it is presumed that the action of Zn and Mn is involved in the diffusion reaction between Cu and Sn to suppress the formation of the embrittlement layer. Hot workability is Cu-Sn alloy, especially high Sn of 3-8% Sn
This is a problem of the alloy and is caused by Sn segregation at grain boundaries and the action of P. Additive elements such as Cr, Co, Ti, and Zr are also finely crystallized to prevent the segregation and improve the hot workability. In addition, V, Mg, Be, Fe, Te, Sb,
Similar effects were observed for Bi, Y and rare earth elements.

Therefore, the Mn content is 0.03 to 2.0.
The reason why the content is limited to% is that if it is less than the lower limit, a sufficient effect cannot be obtained, and if it exceeds the upper limit, the conductivity and workability, especially bending formability are deteriorated. Further, the total content of any one or more of Cr, Co, Ti, and Zr (hereinafter abbreviated as Cr and the like) is limited to 0.05 to 1%, because the above effect is obtained when the content is less than 0.05%. This is because it is difficult to exert the effect, and if it exceeds 1%, workability such as cold working is impaired. Further, the P content is limited to 0.1% or less because the above-mentioned improving effect is difficult to be practically exhibited at an excessive concentration exceeding this. That is, excessive P binds with Cr and the like, and not only reduces the effect of adding Cr and the like, but also hinders workability.

The alloy of the present invention utilizes precipitation hardening. After high temperature hot working at 700 to 1050 ° C., 15 ° C./s.
The reason for cooling at least 400 ° C. at a rate of ec or more is to suppress the precipitation of the above-mentioned precipitates, and the cooling rate is 1
If it is less than 5 ° C / sec, coarse granular precipitation occurs, and the above effect cannot be obtained. Further, the reason why the heat treatment is performed at 400 to 650 ° C. after performing the cold working of 30% or more is to cause uniform fine precipitation due to the working strain, and the uniform fine precipitation is obtained with the working strain of less than 30%. I can't.

[0015]

EXAMPLE An alloy having the composition shown in Table 1 was melted in a charcoal-coated graphite crucible, cast into a mold to form a small ingot (3 kg), which was externally cut into a plate having a thickness of 10 mm. 90 this
After heating to 0 ° C., hot rolling was performed to a thickness of 1.2 mm.
The rising temperature was 710 to 750 ° C., and this was immediately water-cooled. The cooling rate up to 400 ° C was about 20 ° C / sec. After pickling this, cold-roll it to a thickness of 0.6 mm,
Heat treatment was performed at 550 ° C. for 30 minutes. This is 0.21m
After rolling to m, low temperature annealing was performed at 310 ° C. for 20 minutes. About these, conductivity, tensile strength, elongation, bendability,
The solder joint strength and SCC were examined, and the results are shown in Table 2.

Bendability is 9 with push rods of various tip radii (R).
Using a 0 ° groove die, bending was performed by a press, and micro cracks at corners were inspected, and comparison was made by the ratio of the minimum radius R at which no crack was generated and the plate thickness (t). Regarding the solder joint strength, after the lead wire was soldered (4.5 mm ² ), the pull strength was measured after aging at 150 ° C. for 300 hours, and the deterioration of the solder joint with time was compared. SCC is 3V according to JISC8306
A constant load of 40 kg / mm ² was applied in ol% NH ₃ gas, and the time until breakage was determined.

[0017]

[Table 1]

[0018]

[Table 2]

As is clear from Tables 1 and 2, the alloy Nos. No. 1 is excellent in all properties, and the comparative alloy No. 1 made of conventional phosphor bronze. It can be seen that, as compared with No. 4, a high conductivity is exhibited. In particular, comparative alloy No. In No. 4 alloy of the present invention, although not only cracks at the time of hot rolling but also SCC are caused at the time of hot rolling and the solder joint strength is inferior. It can be seen that in No. 1, edge cracking does not occur during hot rolling, SCC is suppressed, and solder joint strength is also improved.

Comparative alloy Nos. Out of the composition range of the alloy of the present invention. In Nos. 2 to 4, it can be seen that any one or more of the required characteristics is inferior. That is, the comparative alloy No. 1 containing no Mn, Cr, etc. No. 4 not only causes SCC, but also has poor solder joint strength and has a large Mn content. In the case of No. 2, the conductivity is markedly reduced. In addition, the comparative alloy N with a high P content
o. In Comparative Alloy No. 3, the bendability was poor and the content of Cr and the like was high. In No. 5, cracking was remarkable in hot rolling, and subsequent processing was stopped.

[0021]

As described above, according to the present invention, Cu-Sn
All of the above improvements (1) to (6) have been improved while making use of the alloy's excellent mechanical strength and precision workability. It is an electrical and electronic device, especially a semiconductor lead material, connector, switch,
As a contact spring and a terminal of a relay or the like, industrially significant effects can be obtained such that practical properties such as strength, conductivity, plating property, and solderability can be satisfied.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeo Shinozaki 500 Kiyotaki-cho, Nikko City, Tochigi Prefecture Furukawa Electric Co., Ltd. Nikko Denki Copper Works (56) References JP 59-153853 (JP, A) JP Sho 61-413 (JP, B2) Japanese Patent Sho 60-59979 (JP, B2)

Claims (2)

(57) [Claims] 1. Sn: 0.05 to 2 wt%, P: 0.0
05-0.1 wt%, Mn: 0.03-2.0 wt%, and any one or two of Cr, Co, Ti, and Zr.
A copper alloy for electronic and electrical equipment, containing a total of 0.05 to 1 wt% of the seeds and the balance Cu. 2. Sn: 0.05 to 2 wt%, P: 0.0
05-0.1 wt%, Mn: 0.03-2.0 wt%, and any one or two of Cr, Co, Ti, and Zr.
An alloy containing 0.05 to 1 wt% in total of the seeds or more and the balance Cu is hot worked at 700 to 1050 ° C., then cooled to at least 400 ° C. at a rate of 15 ° C./sec or more, and then 30%. After performing the above cold working, 4
A method for producing a copper alloy for electronic and electrical equipment, characterized by performing heat treatment at 00 to 650 ° C.