JP2555067B2 - Manufacturing method of high strength copper base alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is excellent in high strength and is used as a spring material and a distribution material such as a lead material, a switch, a terminal and a connector of an electronic / electrical device, particularly an electronic component. The present invention relates to a method for producing a high-strength copper-based alloy that exhibits plating properties, solder joint properties, corrosion resistance, heat resistance, and the like.

[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, according to the manufacturing method of the present invention, Sn is more than 1.5 wt% and 10 wt% or less (hereinafter wt% is simply referred to as%), Ni 0.1 to 10%, Si 0.1 to 5%
Or contains Zn2.5% or less, Fe2.5% or less, Mn2.5%
Less than Co2.5%, less than Al2.5%, less than Mg0.5%, less than As0.5%, less than Ca0.5%, less than V0.5%, less than Y0.5%, rare earth element 0.
5% or less, In0.5% or less, Pb0.5% or less, Sb0.5% or less, Bi0.5
% Or less, Te 0.5% or less, Ag 0.5% or less, Au 0.5% or less, P 0.5%
Below, B 0.5% or less, Cr 0.5% or less, Ga 0.5% or less, Ti 0.5% or less, Zr 0.5% or less, Ge 0.5% or less, any one or two or more After continuously casting a copper alloy containing a total of 3.0% or less and 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 ingot after grinding 20
Cold working at a working rate of up to 95%, then heating in a non-oxidizing atmosphere at 300 to 950 ° C for 5 seconds to 24 hours, and then cooling at a cooling rate of 0.01 to 500 ° C / second, and the cooled material After cleaning the surface of by pickling or grinding or a combination of these,
It is characterized in that it comprises a step of repeating cold working at a working rate of 5 to 90% and then heat treating at 200 to 650 ° C. for 5 seconds to 24 hours in a non-oxidizing atmosphere at least once. .

[Work]

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

Sn, Ni and Si are for increasing the strength of the alloy, and if each is less than the lower limit, sufficient strength cannot be obtained, and if it exceeds the upper limit, high strength can be obtained, but cold workability and bend formability are significantly deteriorated. This is because the solderability and plating adhesion are further reduced.

Zn, Fe, Mn, CO, Al, Mg, As, Ca, V, Y, rare earth element (RE), In,
Pb, Sb, Bi, Te, Ag, Au, P, B, Cr, Ga, Ti, Zr, Ge (hereinafter referred to as "subcomponents") all improve the strength and solderability, plating adhesion and castability This is because, if the respective upper limits are exceeded or the total of two or more types exceeds 3%, conversely, the castability, solderability and 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 950 ° 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 950 ° C. to deteriorate the subsequent properties. 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 alloys with the composition shown in Table 1, 0.5 mm per side of a horizontally continuous cast ingot (thickness 10 mm) was face-rolled, cold-rolled to a thickness of 1.5 mm, and then heat treated at 610 ° 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 and cold-rolled to a thickness of 0.42 mm, followed by heat treatment at 480 ° 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 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. 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. 5 alloy shown in Table 1, a horizontally ingot-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 carried out at 480 ° C. for 1 hour, followed by cooling at a rate of 0.03 ° C./sec. The material surface is then cleaned again and cold-rolled to a thickness of 0.25 mm, then 30
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. 5 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 at 580 ° 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. 5 alloy shown in Table 1, horizontal ingots (thickness 10 mm) were chamfered by 0.5 mm per side, cold-rolled to a thickness of 1.5 mm, and then at 610 ° C. It was heat-treated for 2 hours and then cooled at a rate of 0.03 ° C./sec. Then, the surface of the cooled material is cleaned, cold rolled to a thickness of 0.42 mm, heat treated at 480 ° C for 1 hour, 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
11, No. 12 to 14, No. 18 to 21 and No. 24 to 27 are all tensile strength 68Kg f / mm ² or more, elongation 9.5% or more, bending formability 0.8 or less, solder joint strength 0.9Kg It can be seen that it exhibits characteristics of f / mm ² or more and also 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 61-272339 (JP, A) JP 61-44142 (JP, A) JP 61-99647 (JP, A)

Claims (1)

(57) [Claims] 1. Sn in excess of 1.5 wt% and 10 wt% or less, Ni 0.1 to 10 wt
%, Si 0.1 to 5 wt% or Zn2.5 wt% or less, Fe
2.5wt% or less, Mn2.5wt% or less, Co2.5wt% or less, Al2.5wt%
Below, Mg 0.5 wt% or less, As 0.5 wt% or less, Ca 0.5 wt% or less, V0.
5 wt% or less, Y 0.5 wt% or less, rare earth element 0.5 wt% or less, In0.
5wt% or less, Pb0.5wt% or less, Sb0.5wt% or less, Bi0.5wt% or less, Te0.5wt% or less, Ag0.5wt% or less, Au0.5wt% or less, P0.5w
t% or less, B 0.5 wt% or less, Cr 0.5 wt% or less, Ga 0.5 wt% or less, T
i 0.5wt% or less, Zr 0.5wt% or less, Ge 0.5wt% or less, and one or more of them are included in total 3.0wt% or less, and the balance C
After continuously casting a copper alloy consisting of u and unavoidable impurities, a step of grinding and removing segregation layers and ingot defects on the surface of the ingot,
The ground ingot is cold worked at a working rate of 20 to 95% and then heated in a non-oxidizing atmosphere at 300 to 950 ° C for 5 seconds to 24 hours,
After the step of cooling at a cooling rate of 0.01 to 500 ° C / second and the surface of the cooled material are cleaned by pickling or grinding or a combination of these, cold working is performed at a working rate of 5 to 90%. A process for producing a high-strength copper-based alloy, which comprises a step of repeating heat treatment at 200 to 650 ° C. for 5 seconds to 24 hours in a non-oxidizing atmosphere one or more times.