JP2555069B2 - Manufacturing method of high strength copper base alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lead material for electronic / electrical devices, particularly electronic parts,
The present invention relates to a method for producing a high-strength copper-based alloy, which has high strength and is used as a spring material such as switches, terminals, connectors, etc.

[Problems to be solved by conventional technology and invention]

Many are used in electronic equipment parts such as semiconductor (Tr, IC, LSI, VLSI, etc.) lead frame materials, heat sink materials, electronic parts lead materials, component (connectors, switches, relays, etc.) spring materials, and various terminal materials. Copper alloys have been used.
In recent years, with the miniaturization, high performance, and high density of electronic device parts, higher performance alloys have been required. Especially, the semiconductors at the leading edge are remarkably highly integrated. Is required to have high strength.

Cu-Sn-P is a typical copper alloy with excellent strength.
System, Cu-Ni-Sn system, Cu-Zn-Pb system, Cu-Ni-Si system alloys are known, but these alloys have poor hot workability or because of solution treatment. It is necessary to solve the above-mentioned capital investment and various problems associated therewith, which significantly reduces productivity and contributes to high costs.

Even in the case of such an alloy having poor hot workability, hot working is indispensable for material production, and various methods have been considered for that purpose, but the following problems have not been overcome.

(1) Since high temperature heating in the atmosphere is required during hot rolling, a multi-layered, large amount of oxide scale is generated on the material surface during this treatment, and this oxide scale is generated also during hot working.
Therefore, a large amount of grinding is required to remove it, resulting in a decrease in material yield, and internal defects due to internal oxidation of additive elements and inclusion of oxide scale during rolling, which lowers solderability and plating adhesion. Cause

(2) Reheating cracking due to atmospheric heating and cracking during hot working cause a decrease in yield and an increase in production cost.

(3) Since the material is heated to a high temperature during hot working, a large amount of energy and accompanying capital investment are required, resulting in an increase in production cost.

[Means for solving problems]

As a result of various studies in view of the above, the present invention has developed a method for producing a high-strength copper-based alloy that omits hot working, which is a source of the above-mentioned problems.

That is, the production method of the present invention includes Sn2.5 to 10 wt% (hereinafter wt% is simply referred to as%), Ti 0.1 to 3.0%, or Zn2.5%
Below, Ni1.0% to 2.5%, Mn2.5% or less, Co2.5% or less, Al2.5% or less, Mg0.5% or less, As0.5% or less, Ca0.5% or less, V0. 5% or less, Y 0.5% or less, rare earth element 0.5% or less, In0.
5% or less, Pb 0.5% or less, Sb 0.5% or less, Bi 0.5% or less, Te 0.5
% Or less, Ag 0.5% or less, Au 0.5% or less, P 0.5% or less, B 0.5% or less, Ga 0.5% or less, Zr 0.5% or less, Ge 0.5% or less A step of continuously casting a copper alloy containing one or two or more of 3.0% or less with the balance Cu and unavoidable impurities, and then grinding and removing segregation layers and ingot defects on the surface of the ingot, and the ground casting Cold work the ingot at a working rate of 20-95%, then heat it in a non-oxidizing atmosphere at 300-900 ° C for 5 seconds-24 hours, then 0.01
After cooling at a cooling rate of ~ 500 ° C / sec and cleaning the surface of the cooled material by pickling or grinding or a combination of these, cold working at a working rate of 5 to 90%, and then It is characterized by comprising a step of repeating the heat treatment at 200 to 650 ° C. for 5 seconds to 24 hours in a non-oxidizing atmosphere once or more.

[Work]

The reason why the composition of the alloy used in the present invention is limited as described above is as follows.

Sn and Ti are for increasing the strength of the alloy, and if each is less than the lower limit, sufficient strength cannot be obtained, and if they exceed the upper limit, high strength can be obtained, but cold workability and bending formability are significantly deteriorated. This is because solderability and plating adhesion are reduced.

Zn, Ni, Mn, Co, Al, Mg, As, Ca, V, Y, rare earth element (RE), In,
Pb, Sb, Bi, Te, Ag, Au, P, B, Ga, Zr, Ge (hereinafter referred to as subcomponents)
In order to improve strength and solderability, plating adhesion, and castability. If the respective upper limits are exceeded, or if the total of two or more types exceeds 3%, the castability and solderability will be adversely affected. This is because the attachability and the plating adhesion are deteriorated.

Next, in the continuously cast ingot, the surface layer is mechanically or / and chemically ground to remove defects and segregation during casting, and cold working is performed by recrystallization by the next heat treatment. Therefore, the reason for limiting the working ratio of this cold working to 20 to 95% is that if it is less than 20%, it is insufficient to cause recrystallization by the next heat treatment, and if it exceeds 95%, the material structure is This is because of the non-uniformity of. Heat treatment temperature after cold working
The reason for limiting the temperature to 300 to 900 ° C. is that recrystallization of the material is insufficient at a temperature lower than 300 ° C., and coarse crystal grains are generated at a temperature higher than 900 ° C. to deteriorate the characteristics thereafter. Further, the heat treatment time is limited to 5 seconds to 24 hours. If the heat treatment time is less than 5 seconds, there is no effect of annealing accompanied by recrystallization, and heat treatment for more than 24 hours lowers productivity and causes a cost increase. Further, the cooling rate after the heat treatment is limited to 0.01 to 500 ° C./sec. When the cooling rate is less than 0.01 ° C./sec, it takes a long time to finish cooling, which lowers the productivity and causes coarse precipitates of Cr. It causes growth, and if it exceeds 500 ℃ / sec,
This is because the problem of material deformation occurs due to the temperature difference due to cooling.

Furthermore, the material that has been cooled after the heat treatment is melted and / or cleaned to clean the surface of the material by removing the oxidation of the material during the manufacturing process and the discoloration during the heat treatment due to the adhesion of rolling oil during cold rolling. However, if this is left as it is for commercialization, the solderability and the plating adhesion are significantly reduced, and the reliability is greatly impaired. In order to prevent this, it is dissolved or / and ground with acid or buff,
By removing the surface defect portion, the deterioration of the above characteristics can be suppressed. The removal amount is preferably about 0.1 to 5 μm, and if the removal amount is exceeded, the surface becomes rough and the solderability and plating adhesion are deteriorated. Although cold working is applied to this surface-cleaned material, the processing rate is limited to 5 to 90% because the flatness and surface roughness of the material cannot be improved by processing less than 5%. Also, the required strength cannot be obtained, and processing exceeding 90% causes nonuniformity of the material structure. The reason why the subsequent heat treatment is limited to 200 to 650 ° C for 5 seconds to 24 hours is that the heat treatment after finishing process removes the heat treatment and internal strain, and the intermediate annealing facilitates the subsequent processes. Outside the range, desired characteristics cannot be obtained.

By appropriately repeating the above-mentioned surface cleaning, cold working and heat treatment, it is possible to obtain a material which is smooth and has high strength and elongation excellent in surface property without surface defects. Therefore, it is desirable that the heat treatment after finishing is carried out at 200 to 560 ° C. for 5 seconds to 24 hours and below the recrystallization temperature, and the intermediate annealing is carried out at 400 to 650 ° C. for 10 seconds to 24 hours in the recrystallization region. Further, the above heat treatment and heat treatment are performed in a non-oxidizing atmosphere in order to suppress surface and internal oxidation of the material. Further, in the present invention, in order to finally remove strain and correct the shape, it is possible to adjust to desired characteristics by performing tension leveler, tension annealing or the like.

〔Example〕

For the alloys with the compositions shown in Table 1, a horizontal continuous cast ingot (thickness 10 mm) was chamfered by 0.5 mm per side, cold-rolled to a thickness of 1.5 mm, and then heat treated at 640 ° C for 2 hours. Then, it was cooled at a rate of 0.03 ° C./sec. Subsequently, the surface of the cooled material is cleaned, cold-rolled to a thickness of 0.42 mm, heat-treated at 500 ° C for 1 hour, and then 0.03 ° C /
Cooled at a rate of seconds. Then, the surface of the cooled material was cleaned again, cold-rolled to a thickness of 0.25 mm, heat-treated at 320 ° C. for 2 hours, and then cooled at a rate of 0.05 ° C./sec. The tensile strength, elongation, bendability, solder joint strength and plating adhesion of these materials were examined. The results are also shown in Table 1.

The bending formability was expressed by the ratio (R / t) of the tip radius (R) and the plate thickness (t) at which the cracks were generated by bending with 90 ° dies having different tip radii (R) and examining the occurrence of microcracks. . The folding axis was parallel to the rolling direction. Regarding the solder joint strength, a pulling lead wire was eutectic-soldered on a surface having a diameter of 12 mm, and then held at 150 ° C. for 600 hours, and then a tensile test was conducted. For plating adhesion, Sn-5% Pb alloy was plated to a thickness of 7.5 μm using a borofluoride bath, then held at 105 ° C for 1000 hours, then bent at 180 ° and the bent part The peeling of the plating layer was examined under a microscope.

Next, for the No. 3 alloy shown in Table 1, a horizontal continuous cast ingot (thickness 10 mm) was chamfered by 0.5 mm per side, cold rolled to a thickness of 1.5 mm, and then heat treated. The conditions shown in Table 2 are followed, and then the surface is cleaned to a thickness of 0.42
After cold rolling to mm, heat treatment was performed at 500 ° C. for 1 hour, and then cooling was performed at a rate of 0.03 ° C./sec. Then the surface of the material is cleaned again and cold-rolled to a thickness of 0.25 mm, then 32
It was heat-treated at 0 ° C. for 2 hours and then cooled at a rate of 0.05 ° C./sec. The tensile strength, elongation, bendability, solder joint strength, and plating adhesion of these materials were examined in the same manner as above. The results are also shown in Table 2.

Next, for the No. 3 alloy shown in Table 1, a horizontally continuous ingot (thickness 10 mm) was chamfered by 0.5 mm per side, cold-rolled to a thickness of 1.5 mm, and then at 480 ° C. It was heat-treated for 5 hours and then cooled at a rate of 0.02 ° C./sec. Subsequently, the surface of the cooled material was cleaned and then cold-rolled at the processing rate shown in Table 3, heat-treated at 300 ° C. for 2 hours, and then cooled at a rate of 0.05 ° C./sec. The tensile strength, elongation, bendability, solder joint strength, and plating adhesion of these materials were examined in the same manner as above. The results are also shown in Table 3.

Next, for the No. 3 alloy shown in Table 1, a horizontally continuous cast ingot (thickness 10 mm) was chamfered by 0.5 mm per side, cold-rolled to a thickness of 1.5 mm, and then at 640 ° C. It was heat-treated for 2 hours and then cooled at a rate of 0.03 ° C./sec. Subsequently, the surface of the cooled material is cleaned, cold-rolled to a thickness of 0.42 mm, heat-treated at 500 ° C for 1 hour, and then 0.03 ° C.
Cooled at a rate of / sec. The surface of this was cleaned again, cold-rolled to a thickness of 0.25 mm, and then heat-treated under the conditions shown in Table 4. For these, tensile strength,
The elongation, bendability, solder joint strength and plating adhesion were investigated. The results are also shown in Table 4. Both the heat treatment and the heat treatment in the examples were performed in N ₂ gas.

As is clear from Tables 1 to 4, the present invention method No. 1 to
Nos. 10, No. 12 to 14, No. 18 to 21 and No. 24 to 27 all have tensile strength of 70.5 kgf / mm ² or more, elongation of 10.9% or more, bending formability of 0.8 or less, solder joint strength of 0.8 kgf. It can be seen that it exhibits characteristics of / mm ² or more and has good plating adhesion.

On the other hand, in Comparative Methods No. 15 to 17, No. 22 to 23, and No. 28 to 29, which deviate from the manufacturing conditions specified in the present invention, it is understood that any one or more of the above characteristics is deteriorated.

〔The invention's effect〕

The production method of the present invention eliminates hot working, which is a source of problems such as generation of oxide scale on the surface of the material during processing, internal oxidation, and inclusion of oxide scale. It is manufactured and does not require much energy for heating the material to a high temperature during hot working and the capital investment accompanying it, which can improve the yield and reduce the production cost. It is effective.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Shiga 500 Kiyotaki Town, Nikko City Furukawa Electric Co., Ltd. Nikko Denki Copper Works (56) Reference JP-A-61-143566 (JP, A) JP Sho 62-47465 (JP, A)

Claims (1)

(57) [Claims] Claims: 1. Contains Sn2.5-10wt%, Ti0.01-3.0wt%,
Alternatively, Zn 2.5 wt% or less, Ni 1.0 wt% or more and 2.5 wt% or less, Mn 2.5 wt% or less, Co 2.5 wt% or less, Al 2.5 wt% or less, Mg 0.5
wt% or less, As 0.5 wt% or less, Ca 0.5 wt% or less, V 0.5 wt% or less,
Y0.5wt% or less, rare earth element 0.5wt% or less, In0.5wt% or less,
Pb 0.5wt% or less, Sb 0.5wt% or less, Bi 0.5wt% or less, Te 0.5wt
% Or less, Ag 0.5 wt% or less, Au 0.5 wt% or less, P 0.5 wt% or less, B
0.5wt% or less, Ga0.5wt% or less, Zr0.5wt% or less, Ge0.5wt%
Within the following range, 3.0% by weight of one or more kinds in total
Including the following, after continuously casting a copper alloy consisting of the balance Cu and unavoidable impurities, a step of grinding and removing the segregation layer and the ingot defects on the surface of the ingot, and the grinding ingot at a working rate of 20 to 95%. Cold working, then in non-oxidizing atmosphere at 300-900 ℃ for 5 seconds
After heating for 24 hours, cooling at a cooling rate of 0.01 to 500 ° C / sec, and cleaning the surface of the cooled material by pickling or grinding or a combination of these, and then cooling at a processing rate of 5 to 90%. A process for producing a high-strength copper-based alloy, which comprises a step of repeating hot working and then heat treatment in a non-oxidizing atmosphere at 200 to 650 ° C. for 5 seconds to 24 hours at least once.