JP2555070B2 - 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 equipment, especially electronic parts,
The present invention relates to a method for producing a high-strength copper alloy having high strength and excellent plating properties, solder joint strength, corrosion resistance, heat resistance, etc., which can be used as a switch, terminal, connector, and other distribution materials and spring materials.

[Problems to be solved by conventional technology and invention]

Many are used for electronic equipment parts, such as semiconductor lead frame materials such as transistors, ICs, LSIs, VLSIs, diodes, heat sink materials, lead materials for electronic parts, spring materials and various terminal materials for components such as connectors, switches and relays. Copper alloy is used. In recent years, with the miniaturization, high performance, and high density of electronic device parts, higher performance alloys have been required. Especially, semiconductors at the leading edge are remarkably highly integrated, and lead materials used for them. Requires high strength.

Typical of such copper alloys having excellent strength are conventional Cu-Sn-P-based alloys, Cu-Ni-Sn-based alloys, and Cu-Zn-Pb-based alloys. In addition, since hot working is indispensable and, in addition, the hot workability is poor, the following problems occur, resulting in deterioration in quality and increase in cost.

(1) During hot rolling and hot working, high temperature heating in the atmosphere causes multi-layers and a large amount of oxide scale on the material surface,
A large amount of grinding is required to remove this, and the material yield decreases, and internal defects occur due to internal oxidation of additive elements and inclusion of oxide scale during rolling, which reduces solderability and plating adhesion. .

(2) Reheat cracking due to atmospheric heating and cracks during hot working occur, and these cracks reduce the yield, thus increasing the production cost.

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

[Means for solving problems]

The present invention has been developed in a method for producing a high-strength copper-based alloy that solves the above problems by eliminating the hot working step as a result of various studies in view of this, and includes Ti 0.01 to 5.0 wt%,
Furthermore, 2.2 wt% or less of Sn and 2.5 wt% or less of Ni, Zn, and
Mn, Co, Al and Mg, As, Ca, V, Y, rare earth elements, In, Pb, Sb, Bi, Te, Ag, Au, P, B, Cr, Ga, Zr, Ge of 0.5 wt% or less respectively 1 or 2 or more of 5.0 wt% or less in total, the copper alloy consisting of the balance Cu and unavoidable impurities is continuously cast, and after grinding the surface of the ingot, the working rate is 20 to 95%. Cold working,
Then, after the step of heating in a non-oxidizing atmosphere at 300 to 900 ° C. for 5 seconds to 24 hours and cooling at a cooling rate of 0.01 to 500 ° C./second, the surface is cleaned by melting or grinding, and 90
It is characterized in that cold working is performed at a working rate of%, and then a step of heating in a non-oxidizing atmosphere at 200 to 650 ° C. for 5 seconds to 24 hours is repeated once or more.

[Work]

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

The reason why the Ti content is limited to 0.01 to 5.0 wt% is that the desired strength cannot be obtained if the Ti content is less than 0.01 wt%, and it is high when the Ti content exceeds 5.0 wt%. This is because the strength can be obtained, but the cold workability and the bendability are largely deteriorated, and the solderability and the plating adhesion are also deteriorated.

In addition, Sn, Ni, Zn, Mn, Co, Al, Mg, As, Ca, V, Y, rare earth elements,
In, Pb, Sb, Bi, Te, Ag, Au, P, B, Cr, Ga, Zr, Ge (hereinafter, these are referred to as subcomponents), 2.2 wt% or less Sn and
Ni, Zn, Mn, Co, Al less than 2.5wt% and less than 0.5wt% respectively
Mg, As, Ca, V, Y, rare earth elements, In, Pb, Sb, Bi, Te, Ag, Au, P, B, C
The reason why one or more of r, Ga, Zr, Ge is limited to 5.0 wt% or less in total is that by adding these, good strength, solderability, plating adhesion and excellent electronic parts are obtained. This is because it has castability, and if the total amount added exceeds 5.0 wt%, castability, solderability, and plating adhesion will be poor.

Next, the surface grinding after continuously casting the alloy of the above composition is
This is to remove defects and segregation during casting, and the surface layer may be ground by a mechanical or chemical method. The reason for limiting the working rate of the subsequent cold working to 20 to 95% is that if it is less than 20% it is insufficient to cause recrystallization during the heat treatment in the subsequent process, and if it exceeds 95%, the non-uniformity of the material structure occurs. This is because it invites.

In the subsequent heat treatment, the heating temperature was limited to 300-900 ° C because the recrystallization of the material was insufficient below 300 ° C.
This is because when the temperature exceeds ℃, coarse crystal grains are generated and the characteristics are deteriorated. Furthermore, the reason for limiting the heating time to 5 seconds to 24 hours is 5
This is because if it is less than 2 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. The reason why the cooling rate after that is limited to 0.01 to 500 ° C / sec is that if it is less than 0.01 ° C / sec, it takes a long time to finish the cooling and the productivity is lowered, and if it exceeds 500 ° C / sec, it is accompanied by cooling. This is because the material is deformed due to the temperature difference inside the material. The reason why the above heat treatment is performed in a non-oxidizing atmosphere is to prevent the surface and the inside of the material from being oxidized.

Next, the surface is cleaned by melting or grinding, because the discoloration during heat treatment due to the oxidation of materials during the manufacturing process and the adhesion of rolling oil during cold rolling is left as it is for solderability and This is to prevent the plating adhesion from being significantly reduced and the reliability to be greatly impaired, so it is desirable to remove the surface layer by about 0.1 to 5 μm using acid or buff, and if it exceeds 5 μm, the surface will become rough. Solderability and plating adhesion will be reduced.

5% limited the subsequent cold working to 5 to 90%
If it is less than 90%, the flatness and surface roughness of the material are inferior and the strength is small, and if it exceeds 90%, nonuniformity of the material structure is caused. Further, if the subsequent heat treatment is final annealing after finishing, the heat treatment is performed for the purpose of refining the material and removal of internal strain, while if it is intermediate annealing, the heat treatment is for subsequent processing. The heating temperature is limited to 200 to 650 ° C. and the heating time is limited to 5 seconds to 24 hours because the intended purpose cannot be achieved outside these ranges. It should be noted that in the case of final annealing, it is desirable to perform the treatment at a recrystallization temperature or lower, that is, at 200 to 560 ° C. for 5 seconds to 24 hours, and in the case of intermediate annealing, a temperature above the recrystallization temperature, ie 400
Treatment at ~ 650 ° C for 10 seconds to 24 hours is desirable. Further, the reason for performing the heat treatment in a non-oxidizing atmosphere is to suppress the surface and internal oxidation of the material.

Further, by appropriately repeating the above-mentioned surface cleaning and subsequent cold working and heat treatment, it is possible to obtain a material having high strength and good elongation which is smooth, has no surface defects, and has excellent surface properties.

Finally, the desired characteristics can be adjusted by performing tension leveler or tension annealing for strain relief and shape correction.

〔Example〕

 Next, examples of the present invention will be described.

Alloys with the compositions shown in Table 1 were each melted to obtain ingots with a thickness of 10 mm by horizontal continuous casting, and each side was ground by 0.5 mm and cold-rolled to a thickness of 1.5 mm, then in a non-oxidizing atmosphere. The temperature was maintained at 580 ° C for 2 hours, and the cooling rate was 0.03 ° C / sec. After that, the surface is cleaned, cold-rolled to a thickness of 0.42 mm, then held in a non-oxidizing atmosphere at 540 ° C for 1 hour for intermediate annealing, and cooled at a cooling rate of 0.03 ° C / sec. After the surface was cleaned again and the thickness was reduced to 0.25 mm by cold rolling, finish annealing was carried out by holding at 300 ° C. for 2 hours in a non-oxidizing atmosphere, and cooled at a cooling rate of 0.05 ° C./sec. Tensile strength, elongation, bendability, solder joint strength, and plating adhesion were investigated for each of the test materials according to the present invention, and the results are also shown in Table 1.

The bending formability is determined by bending the test material with the tip bending axis of a 90 ° die having a different tip radius (R) parallel to the rolling direction of the test material, and checking for microcracks to determine the plate thickness (t ), The solder joint strength is determined by conducting a tensile test after eutectic soldering the lead wire for tension to the 12 mm diameter part of the test material and holding it at 150 ° C for 600 hours. In addition, the plating adhesion is determined by plating the test material with a borofluoride bath of Sn-5% Pb alloy to a thickness of 7.5 μm, holding it at 105 ° C for 1000 hours, and then bending it to 180 °. The presence or absence of peeling of the plated layer was examined under a microscope.

Next, the alloy of composition No. 3 in Table 1 was melted and continuously cast horizontally to obtain an ingot with a thickness of 10 mm, the ingot was ground by 0.5 mm on each side, and the thickness was 1.5 mm by cold rolling. After that, heat treatment was performed in a non-oxidizing atmosphere under the conditions shown in Table 2,
After that, the surface is cleaned and cold-rolled to a thickness of 0.42 mm, held in a non-oxidizing atmosphere at 460 ° C for 1 hour for intermediate annealing, cooled at a cooling rate of 0.03 ° C / sec, and the surface is cleaned again. And cold-rolled to a thickness of 0.25 mm, held in a non-oxidizing atmosphere at 300 ° C for 2 hours for finish annealing, and cooled at a cooling rate of 0.05 ° C / sec. Tensile strength, elongation, bendability, solder joint strength, and plating adhesion were investigated and the results are also shown in Table 2.

Next, the alloy of composition No. 3 in Table 1 was melted and continuously cast horizontally to obtain an ingot with a thickness of 10 mm, the ingot was ground by 0.5 mm on each side, and the thickness was 1.5 mm by cold rolling. After that, the product was kept at 480 ° C for 5 hours in a non-oxidizing atmosphere, cooled at a cooling rate of 0.02 ° C / sec to clean the surface, and then cold-rolled under the conditions shown in Table 3. Finish annealing is performed by holding at 300 ° C for 2 hours in a non-oxidizing atmosphere without intermediate annealing, and 0.05 ° C.
The test materials were cooled at a cooling rate of / sec, and the tensile strength, elongation, bendability, solder joint strength, and plating adhesion were investigated, and the results are also shown in Table 3.

Furthermore, melt the alloys of composition No. 3 and No. 7 in Table 1,
Horizontal ingot casting produces a 10 mm thick ingot, and the ingot is single-sided.
After grinding by 0.5 mm and cold rolling to a thickness of 1.5 mm, the product is held in a non-oxidizing atmosphere at 520 ° C for 2 hours, cooled at a cooling rate of 0.03 ° C / sec to clean the surface, and then cold. Rolled to a thickness of 0.42 mm, kept at 460 ° C for 1 hour in a non-oxidizing atmosphere, subjected to intermediate annealing, cooled at a cooling rate of 0.03 ° C / sec, and then cleaned the surface again and cold rolled. Go 0.
With a thickness of 25 mm, finish annealing was performed under the conditions shown in Table 4 to obtain test materials, and tensile strength, elongation, bend formability,
The solder joint strength and plating adhesion were investigated and the results are also shown in Table 4.

As is clear from Tables 1 to 4, all the alloys according to the method of the present invention have a tensile strength of 60.8 kgf / mm or more, an elongation of 10.0% or more, and a solder joint strength of 0.
It has 9kgf / mm or more, and in terms of bendability
It is 0.8 or less, and there is no peeling of the plating layer, which has good characteristics. On the other hand, it can be seen that the alloy according to the comparative method having different manufacturing conditions from the method according to the present invention is inferior to the alloy according to the present invention in at least one characteristic. That is, Comparative method No. 15 has a low solder joint strength and is inferior in bend formability and plating adhesion, and Comparative method No. 17 is poor in bend formability and plating adhesion. In addition, comparative methods No. 23 and No.
No. 29 and No. 22 of Comparative method have low tensile strength.
No. 28 and No. 28 both have low elongation and poor bendability.

〔The invention's effect〕

As described above, according to the present invention, by eliminating the hot working step in the production of alloys used for the lead frame material of electronic device parts, the heat sink material, the lead material of electronic parts, the spring material of component parts and various terminal materials. The cost is reduced, and high strength and excellent workability, solderability, and plating property can be obtained, which is an industrially significant effect.

 ─────────────────────────────────────────────────── ─── 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] 1. A steel containing 0.01 to 5.0 wt% of Ti, 2.2 wt% or less of Sn, 2.5 wt% or less of Ni, Zn, Mn, Co, Al and 0.5 wt% or less of Mg, As, Ca, respectively. , V, Y, rare earth element, In, Pb, Sb,
Continuous casting of a copper alloy containing Bi, Te, Ag, Au, P, B, Cr, Ga, Zr, Ge, and one or more of them in a total amount of 5.0 wt% or less, with the balance Cu and inevitable impurities. , After grinding the surface of the ingot,
Cold work at a working rate of 20 to 95%, then heat at 300 to 900 ° C for 5 seconds to 24 hours in a non-oxidizing atmosphere for 0.01
After the step of cooling at a cooling rate of ~ 500 ° C / sec, the surface is cleaned by melting or grinding, and cold working is performed at a working rate of 5 to 90%, and then 200 to 200 in a non-oxidizing atmosphere. 6
A method for producing a high-strength copper-based alloy, which comprises repeating the step of heating at 50 ° C for 5 seconds to 24 hours once or more.