JP2516622C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to strength, conductivity, plating property, and solderability of electronic and electrical devices, particularly, contact springs and terminals of semiconductor lead materials, connectors, switches, relays and the like. The present invention relates to a copper alloy excellent in practical characteristics such as the above and a method for producing the same. [Prior art] Although Cu alloys are frequently used for parts and members of electronic and electrical equipment, in recent years, economical efficiency has been strongly sought in addition to miniaturization, high density, and high precision. Higher performance and economy have come to be required instead of brass and phosphor bronze. For example, phosphor bronze, which has much better mechanical properties than brass, has a serious problem of solder joint reliability that is universal for electronic and electrical applications in addition to stress corrosion cracking (SCC) susceptibility. As a defect of the same type, when Sn or Sn-Pb alloy (solder) plating is used instead of a noble metal for an electric contact or a connection part, the adhesion is lost with time, and a peeling phenomenon occurs similarly to the solder joint part. . 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. Therefore, as exemplified in JP-B-51-41222 and JP-A-49-108562, a thick Cu or Ni barrier is used. An extra step such as forming the layer in advance by plating or the like is required. For this reason, in part, a Cu—Fe alloy, for example, C194 (2.3 wt% Fe, 0.
12 wt% Zn, 0.03 wt% P, balance Cu) (hereinafter, wt% is abbreviated as%), C
195 (1.5% Fe, 0.6% Sn, 0.2% Co, 0.03% P, balance Cu
) Etc. are used. These alloys have a large amount of Fe precipitated and dispersed in the form of phosphides or metal elements, and not only cause microcracks in precision bending,
There is a problem that the reliability of the solder joint is inferior. [Problems to be Solved by the Invention] Under such circumstances, it is strongly desired to improve the following defects in Cu-Sn alloys having excellent mechanical strength and precision workability. (1) To save the expensive Sn and exhibit the same strength. (2) The strength and the electrical conductivity are in a conflicting relationship, but they must be compatible at a higher value. (3) Do not cause SCC. (4) Solder bonding and peeling over time of Sn, Sn—Pb alloy plating should not occur. (5) The composition is advantageous in production without causing defects such as cracks in hot working. (6) Being made by air melting casting that does not require special equipment. [Means for Solving the Problems] In view of this, the present invention has been subjected to various studies, and as a result, the strength, conductivity, plating property, and the like of electronic and electrical devices, particularly, contact springs and terminals of semiconductor lead materials, connectors, switches, relays and the like, A copper alloy having excellent practical properties such as solderability and a method for producing the same have been developed. As the copper alloy of the present invention, Sn 0.05 to 8%, P 0.001% or more and 0.005%
%, Less than 0.03 to 2.0% Mn, further contains any one or more of Cr, Co, Ti, and Zr in a total of 0.05 to 1%, with the balance being Cu. Is what you do. In addition, the production method of the present invention comprises Sn 0.05 to 8%, P 0.001% or more and 0.005%
Alloy containing 0.03 to 2.0% of Mn, one or two or more of Cr, Co, Ti, and Zr in total of 0.05 to 1% and a balance of 700 to 1050. After hot working at 400 ° C., cooling to at least 400 ° C. at a rate of 15 ° C./sec or more, and then performing cold working of 30% or more,
The heat treatment is performed at 0 ° C. That is, the present invention consists of an alloy having the above composition,
And then cooled to at least 400 ° C. at a rate of 15 ° C./sec or more, then subjected to cold working of 30% or more, and then heat-treated at 400 to 650 ° C. In addition, if the alloy of the present invention is further processed to a desired size after the heat treatment and then subjected to low-temperature annealing at 200 to 400 ° C., elongation and stress relaxation resistance can be improved without losing strength. In applications requiring spring properties, such as connectors, switches, and relays, the Sn content is reduced to 2 to 8%, particularly 4 to 7%.
On the other hand, in the case where conductivity and heat resistance are important such as semiconductor lead material and electric equipment, the Sn content is set to 0.05 to 3%, particularly 0.1 to 2%. [Action] 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. It is advantageous. The additional element is a simple metal, a compound with P, and particularly Zr is Cu ₃ Z.
r and Ti become fine precipitates as TiSn, and can greatly suppress and suppress the SCC sensitivity of the Cu-Sn alloy. In the present invention, P is 0.001% or more and less than 0.005% and the P content of ordinary phosphor bronze (
(0.1-0.25%), and instead uses Mn as a deoxidizing agent. The decrease in P prevents the formation of low melting point phases such as Cu-P and Cu-Sn-P, which are the main causes of cracking during hot working, and significantly improves Sn plating and solderability. That is, the peeled plating and solder joints are all black, and concentrated P is detected in addition to Cu and Sn. This is because P in 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 and solder and phosphor bronze, and ε As the phase becomes more brittle, the strength of the solder joint decreases. In the present invention, the above-mentioned embrittlement phenomenon is prevented by suppressing P to 0.001% or more and less than 0.005%. The addition of Mn not only prevents the above-mentioned embrittlement phenomenon but also improves the hot workability. Also improves mechanical properties. Although the mechanism of the action of Mn is unknown, it is presumed that it participates in the diffusion reaction between Cu and Sn to prevent the generation of an embrittlement layer. Hot workability is a problem of Cu—Sn alloys, particularly high Sn alloys having a Sn content of 3 to 8%, and is caused by Sn segregation at grain boundaries and the action of P. Additional elements such as Cr, Co, Ti, and Zr are also refined to prevent the segregation and improve hot workability. Similar effects were observed for V, Mg, Be, Fe, Te, Sb, Bi, Y, and rare earth elements. Thus, the reason why the content of Mn is limited to 0.03 to 2.0% is that a sufficient effect cannot be obtained below the lower limit, and an electrical conductivity and processability, particularly bending formability, are reduced above the upper limit. It is. The reason why the total content of one or more of Cr, Co, Ti, and Zr (hereinafter abbreviated as Cr, etc.) is limited to 0.05 to 1% is that when the content is less than 0.05%, the above effect is obtained. This is because it is difficult to exhibit, and if it exceeds 1%, workability such as cold work is impaired. The reason why the P content is limited to less than 0.005% is that if the concentration is excessively higher than this, the above-mentioned improvement effect is hardly practically exhibited. That is, excessive P bonds with Cr and the like, and not only reduces the effect of adding Cr and the like, but also impairs workability. The alloy of the present invention utilizes precipitation hardening, and the purpose of cooling to at least 400 ° C. at a rate of 15 ° C./sec or more after high-temperature hot working at 700 to 1050 ° C. is to suppress precipitation of the precipitates. If the cooling rate is lower than 15 ° C./sec, coarse and granular precipitation occurs, and the above effects cannot be obtained. The reason why the heat treatment is performed at 400 to 650 ° C. after the cold working of 30% or more is to cause uniform fine precipitation due to the processing strain, and the uniform fine precipitation is obtained with the working strain of less than 30%. I can't. Example An alloy having a composition shown in Table 1 was melted in a charcoal-coated graphite crucible, cast into a mold to form a small ingot (3 kg), and then externally cut into a plate having a thickness of 10 mm. This is 90
After being heated to 0 ° C., it was hot-rolled to a thickness of 1.2 mm. The rise temperature is 710-7
It was 50 ° C. and immediately cooled with water. The cooling rate to 400 ° C is about 20 ° C / sec.
c. This is pickled and then cold rolled to a thickness of 0.6 mm.
Heat treated for 0 minutes. Further, this was rolled to 0.21 mm and then subjected to low-temperature annealing at 310 ° C. for 20 minutes. The conductivity, tensile strength, elongation, bendability, solder joint strength, and SCC were examined for these, and the results are shown in Table 2. Bendability is determined by using a push rod of various tip radii (R) and a 90 ° groove die, bending by press and inspecting micro cracks at corners, minimum R without cracking and plate thickness (t)
Were compared. After soldering the lead wire (4.5mm ² ),
After aging at 150 ° C. for 300 hours, the pull strength was measured, and the aging of the solder joint was compared. SCC conforms to JIS C8306 and is performed in 4% by volume NH ₃ gas.
A constant load of 0 kg / mm ² was applied, and the time until breaking was determined. [Table 1] [Table 2] As is clear from Tables 1 and 2, the alloy No. 1 of the present invention was used. No. 1 is excellent in all the characteristics, and it can be seen that it shows high conductivity. In particular, the comparative alloy No. No. 4 not only causes edge cracking during hot rolling but also causes SCC and further deteriorates the solder joint strength. In No. 1, it can be seen that edge cracking does not occur during hot rolling, SCC is suppressed, and solder joint strength is improved. On the other hand, the comparative alloy No. which is out of the composition range of the alloy of the present invention. In Nos. 2 to 4, one or more of the required characteristics are inferior. That is, the comparative alloy No. containing no Mn, Cr, or the like. Comparative alloy No. 4 not only causes SCC, but also has poor solder joint strength and a high Mn content. In No. 2, the decrease in conductivity is remarkable. In addition, Comparative Alloy No. Comparative alloy No. 3 is inferior in bendability and has a large content of Cr and the like. In No. 5, cracking was remarkable in hot rolling, and subsequent processing was stopped. [Effects of the Invention] As described above, according to the present invention, all of the above improvements (1) to (6) are improved while taking advantage of the excellent mechanical strength and precision workability of a Cu-Sn alloy. It has industrially remarkable effects such as being able to satisfy practical characteristics such as strength, conductivity, plating properties, and solderability as equipment, especially contact springs for semiconductor lead materials, connectors, switches, relays, etc., and terminals. is there.

Claims (1)

Claims: (1) Sn 0.05 to 8 wt%, P not less than 0.001 wt% and less than 0.005 wt%, Mn 0.03 to 2.0 wt%, and any one of Cr, Co, Ti and Zr
A copper alloy for electronic and electrical equipment containing a total of 0.05% to 1% by weight of one or more kinds and a balance of Cu. (2) Sn 0.05 to 8 wt%, P not less than 0.001 wt% and less than 0.005 wt%, Mn 0.03 to 2.0 wt%, and any one of Cr, Co, Ti and Zr
Alloy containing 0.05% to 1% by weight of the total of at least
After hot working at 0 to 1050 ° C., cooling to at least 400 ° C. at a rate of 15 ° C./sec or more, and then performing cold working of 30% or more,
A method for producing a copper alloy for electronic and electrical equipment, comprising performing a heat treatment at 50 ° C.