JPH03199357A - Manufacture of high strength and high conductivity copper alloy for electronic equipment - Google Patents

Abstract

PURPOSE:To improve the strength, toughness, etc., of the copper alloy by subjecting a copper alloy contg. specified Cr, Sn, Ni, Zn and Cu to hot working, cold working and annealing under prescribed conditions. CONSTITUTION:A copper alloy constituted of, by weight, 0.05 to 1 % Cr, 0.05 to 0.7% Sn, 0.01 to 0.5% Ni, 0.01 to 3% Zn and the balance Cu is refined. The copper alloy is heated at 850 to 1000 deg.C for 0.5 to 5hr, is thereafter hot-rolled and is then cooled at >=1 deg.C/sec cooling rate. Next, the alloy is subjected to cold working at >=50% draft and is annealed at 300 to 600 deg.C for 0.5 to 20hr. After the annealing, the alloy is cold-worked and is furthermore subjected to stress relief annealing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a copper alloy material suitable for lead materials of semiconductor devices such as transistors and integrated circuits (XC circuits), and conductive spring materials for connector terminals, relays, switches, etc. Regarding the manufacturing method of
The present invention provides a high-strength, high-conductivity copper alloy for electronic devices that is particularly strong and has excellent toughness.

[Conventional technology] Conventional lead materials for semiconductor devices have a low coefficient of thermal expansion;
High nickel alloys such as Kovar (F e -29Ni-16Co) and 42 alloy have been preferably used because of their good adhesion and sealing properties with elements and ceramics. However, in recent years,
With the increase in the degree of integration of semiconductor circuits, many ICs with high power consumption have come into use, and more resins have been used as sealing materials, and improvements have been made to the bonding between elements and lead frames. Copper alloys with good heat dissipation properties have come to be used as lead materials.

Furthermore, as materials for springs conventionally used for electrical equipment springs, measuring instrument springs, switches, connectors, etc., inexpensive brass, nickel silver with excellent spring properties and corrosion resistance, or phosphor bronze with excellent spring properties have been used. was.

[Problems to be Solved by the Invention] Generally, lead materials for semiconductor devices are required to have the following characteristics.

(1) The lead must exhibit excellent thermal and electrical conductivity, as it is required to act as an electrical signal transmission part and also to emit heat generated during the balacaging process and circuit use.

(2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

(3) It must have good heat resistance since various heating processes are involved during packaging.

(4) Most leads are manufactured by punching or bending lead material, so the workability of these materials must be good.

(5) Since the surface of the lead is plated with precious metals, the lead must have good plating adhesion to these precious metals.

(6) exposed outside the sealing material after packaging;
Many products are soldered to the so-called outer leads, so good soldering is a sign of good soldering.

(7) Good corrosion resistance from the viewpoint of equipment reliability and service life.

(8) With the transition from DIP type to Quad type,
Future lead materials will be required to have low anisotropy.

(9) Prices are low.

Oxygen-free copper, tin-containing copper, phosphor bronze, Konol, and 42 alloy, which have been conventionally used to meet these various required properties, all have advantages and disadvantages, and they cannot necessarily satisfy all of these properties. do not have.

In addition, brass used as a spring material has poor strength and spring properties, and nickel silver and phosphor bronze, which have excellent strength and spring properties, contain 18% Ni by weight for nickel silver and 8% S by weight for phosphor bronze.
Since this alloy contains n, it is an expensive alloy due to constraints on processing such as poor hot workability in terms of raw materials and production. Furthermore, when used for electrical equipment, etc., it has a drawback of low electrical conductivity. Therefore, the conductivity is good,
The emergence of an inexpensive alloy with excellent spring properties has been awaited.

Although the Cu-Cr-5n-Ni-Zn alloy satisfies the above-mentioned required properties, its strength was inferior to that of the 42 alloy and phosphor bronze.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and
The purpose of this invention is to improve the drawbacks of Cu-Cr-5n-Ni-Zn alloys and to provide a copper alloy that has properties suitable for use as lead materials for semiconductor devices, conductive spring materials, and the like.

It is possible to improve the strength of the Cu-Cr-8n-Ni-Zn system by changing the component composition, but changing the component composition deteriorates various properties such as conductivity and bendability, which is not preferable. .

The present invention provides Cu-Cr-8n-Ni-Zn as described above.
A new manufacturing method was discovered in order to improve only the strength while maintaining the excellent mechanical properties of the alloy.

That is, the first invention has Cr 0.05~], 0νt
%, Sn 0.05-0.7 vt%, Ni 0.
01-0.5 vt% and Z n 0.01-3.0w
In a method of hot working, cold working, and annealing an alloy containing Cu and unavoidable impurities, (1) b After heating, hot rolling is performed, and immediately after the hot rolling, the workpiece is Cooling at a rate of ℃/sec or more, (II) After cooling 5
0% or more cold working is applied to the processed material at 300 to 600℃.
(III) After annealing, cold working is performed and strain relief annealing is performed. The above steps (1) to (III) are performed in sequence. This is a method for producing a high-strength, high-conductivity copper alloy.

Further, the second invention is the first invention, further including A in the alloy composition.
I% Be, CO5Fe, Hf, In.

18 or 2 or more selected from the group consisting of Mgs Mn%P% T is Z r in a total amount of 0.01 to 2.0
wt%, and the steps of hot working, cold working, and annealing are the same as in the first invention.

The reason why the alloy components in each invention are limited as described above is as follows.

Cr is added because it can be expected to cause precipitation hardening due to fine Cr grains, and also to obtain heat resistance associated with it.
The reason for setting the content of r to 0.05 to 1.0% by weight is that C
If the content is less than 0.05% by weight, the above-mentioned effects cannot be expected, and if it exceeds 1.0% by weight, the processability and conductivity will be significantly reduced, and the solderability will also be reduced. It is.

The reason for setting the Sn content to 0.05 to 0.7 vt% and the Ni content to 0.01 to 0.5 vt% is because if any of these additive elements is below the lower limit, the desired strength will not be achieved. This is because if the upper limit is exceeded, the conductivity will be significantly lowered.

Zn is added because it can be expected to significantly improve solder heat resistance and peelability without significantly reducing conductivity, and the amount of Zn added is 0.01 to 3.0 wt%.
If the content is less than 3.0wt%, the above-mentioned effect cannot be expected;
This is because if it exceeds this, a significant decrease in conductivity will occur.

Furthermore, as a subcomponent, A 1% B e s Co ”
-Fe, Hf, In, MgSMn, P, Ti.

One or more selected from the group consisting of Zr in a total amount of 0. The reason for adding 1 to 2.0 wt% of O is that it can be expected to have the effect of improving the strength without significantly reducing the conductivity. If the total amount added is less than 0.01 wt%, the above-mentioned effect cannot be expected. On the other hand, if it exceeds 2.0 wt%, significant deterioration of conductivity and processability will occur.

Moreover, the reasons for limiting the conditions in manufacturing steps (I) to (III) are as follows.

In step (I), the temperature of 850 to 1000°C is 0.
The reason for hot rolling after heating for 5 to 5.0 hours and cooling the workpiece at a rate of 1°C/sec immediately after the hot rolling is completed is as follows.
In order to obtain excellent strength and conductivity, the heating temperature is 850℃.
If the temperature is below 1000°C, there will be a significant decrease in strength.
If the temperature is exceeded, a liquid phase may partially appear. Moreover, if the heating time is less than 0.5 hours, the strength will be significantly reduced, and if it exceeds 5.0 hours, there will be no economic value. Furthermore, if the cooling rate of the processed material after hot rolling is less than 1° C./sec, a significant decrease in strength and conductivity will occur.

In step (II), after cooling, cold working is performed by 50% or more, and the processed material is heated to 0.5 to 2
The reason for annealing for 0.0 hours is that it can be expected to improve strength and conductivity.If the cold working is less than 50% after cooling, no improvement in strength can be expected due to annealing, and if the temperature is 3.
Even if the temperature is below 00℃ or the time is less than 0.5 hours, no improvement in conductivity can be expected, and even if the temperature exceeds 500℃, the time is less than 2 hours.
This is because even if it exceeds 0.0 hours, no improvement in strength can be expected. The most preferable heat treatment conditions are 350
1.0 to 3.0 hours at a temperature of ~450°C.

The reason why cold working is performed after annealing in step (III) is that a significant improvement in strength can be expected. The reason why strain relief annealing is performed at the end is that cold working after annealing significantly improves strength, but reduces elongation and deteriorates bendability, so strain relief annealing is performed to improve bendability again. It's for a reason.

[Example] Next, examples of the present invention will be described.

An alloy having the composition shown in Table 1 was melted to obtain an ingot with a thickness of 30+ nm, and a test material was produced under the manufacturing conditions shown in Table 1. The tensile strength, elongation, and electrical conductivity of these test materials were measured, and a 90" repeated bending test was conducted.
- The number of bends until breakage was measured, with one round trip. Solderability was evaluated by vertical dipping method by immersing the product in a solder bath (60% Sn, 40% Pb) at 230±5° C. for 5 seconds and visually observing the wetting state of the solder. or,
The evaluation of solder heat resistance and peelability was performed by applying a 5μ layer of solder plating to the material (
5n60%, Pb2O%) and kept in a constant temperature bath at 150° C. for up to 1000 hours, taken out every 100 hours and subjected to 90@bending and reciprocating once to check for peeling of solder. These results are shown in Table 1 along with comparative alloys.

/H)/: Sample parallel to the rolling direction 12) l: Sample perpendicular to the rolling direction *3> Good 2 Wet area after soldering 95% or more Poor: Wet area after soldering less than 95% Examples of the present invention and comparison An explanation of the example is given below.

Inventive examples Nos. 1 to 5 are alloys of the components of the present invention manufactured by the manufacturing method of the present invention, and all of them are excellent in strength and conductivity, and have good other properties as well.

Comparative example No. 6 has a low Cr content, so No. 8
No. 10 has a low Sn content, and No. 10 has a low Ni content, so even though they were manufactured using the manufacturing method of the present invention,
The strength is inferior to the inventive example.

In addition, No. 12 had a low Zn content, and therefore had poor solder heat resistance and peelability. Furthermore, No. 7 has a high Cr content, so
No. 19 has a high Sn content, No. 11 has a high Ni content, No. 13 has a high Zn content, so
Although manufactured by the manufacturing method of the present invention, the conductivity was lower than that of the alloy of the present invention, and No. 7 had poor soldering properties.

On the other hand, No. 14 to No. 23 are alloys of the components of the present invention, but N 0.14 has a low ingot heating temperature, so N
No. 15 has a short ingot heating time, No. 16 has a low cooling rate after hot heating, No. 17 has a small working degree before annealing, and No. 18 has a low annealing temperature. No. 19 has a high annealing temperature, No. 20 has a short annealing temperature, No. 21 has a long annealing time, and No. 22 has no cold working after annealing.
The strength is inferior to the example of the present invention. Also, No. 18
, No, 20 also has low conductivity.

Furthermore, since strain relief annealing was not performed on No. 23, the bendability was inferior to that of the examples of the present invention.

[Effects of the Invention] As explained above, according to the present invention, the strength is particularly high;
A high-strength, high-conductivity copper alloy with excellent toughness and no deterioration in other properties can be obtained, and this alloy is excellent as a material for electronic parts used in semiconductor devices.

Claims (2)

[Claims] (1) Cr0.05-1.0wt%, Sn0.05-0
．． 7wt%, Ni0.01-0.5wt% and Zn0.
In a method of hot working, cold working, and annealing an alloy containing 0.01 to 3.0 wt% and the balance consisting of Cu and unavoidable impurities, (I) 0.5 to 5.0 wt% at a temperature of 850 to 1000 °C;
After heating for an hour, hot rolling is carried out, and immediately after hot rolling, the workpiece is cooled at a rate of 1°C/sec or more. (II) After cooling, cold working is performed by 50% or more, and the workpiece is
Annealing at a temperature of 00 to 600°C for 0.5 to 20.0 hours. (III) After annealing, perform cold working and further perform strain relief annealing. The above steps (I) to (III) are performed sequentially. A method for manufacturing a high-strength, high-conductivity copper alloy for electronic devices, characterized by: (2) Cr0.05-1.0wt%, Sn0.05-0
．． 7wt%, Ni0.01-0.5wt%, Zn0.0
1 to 3.0 wt% and Al, Be, Co, Fe, Hf,
Hot working an alloy containing a total amount of 0.01 to 2.0 wt% of one or more selected from the group consisting of In, Mg, Mn, P, Ti, and Zr, and the balance being Cu and unavoidable impurities. In the method of cold working and annealing, (I) 0.5 to 5.0 at a temperature of 850 ° C to 1000 ° C.
After heating for a period of time, hot rolling is performed, and immediately after the hot rolling, the workpiece is cooled at a rate of 1°C/sec or more. (II) After cooling, cold working is performed by 50% or more, and the workpiece is
Annealing at a temperature of 00 to 600°C for 0.5 to 20.0 hours. (III) After annealing, perform cold working and further perform strain relief annealing. The above steps (I) to (III) are performed sequentially. A method for manufacturing a high-strength, high-conductivity copper alloy for electronic devices, characterized by: