JPH07268573A - Production of high strength and high conductivity copper alloy for electronic equipment - Google Patents

Abstract

PURPOSE:To produce a high strength and high conductivity copper alloy for electronic equipment, excellent in strength, electric conductivity, etching characteristic, and bendability. CONSTITUTION:A Cu alloy, which has a composition consisting of 0.05-0.4% Cr, 0.03-0.25% Zr, and the balance Cu with inevitable impurities and further containing, if necessary, 0.06-2.0% Zn or 0.01-1.0%, in total, of one or more elements selected from among Ti, Fe, Ni, Sn, In, Mn, P, Mg, and Si, together with Zn, is used. This Cu alloy is worked and treated by the process consisting of the following stages: (a) solution heat treatment either by annealing at >=700 deg.C and water cooling from the temp. or by regulating hot rolling finishing temp. to >=700 deg.C and performing water cooling at >=100 deg.C/min cooling rate directly after that: (b) cold rolling at >=50% draft: (c) aging treatment at 300-700 deg.C: (d) cold rolling at 30-70% draft: (e) stress relief annealing at 350-700 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength and high-conductivity copper alloy for electronic equipment. More specifically, it is a lead for semiconductor equipment such as transistors and integrated circuits (ICs). The present invention relates to a method for producing a copper alloy suitable for a material, which has high strength, conductivity, and the like, and which has excellent etching property and bending workability.

[0002]

2. Description of the Related Art The trend toward IC packages is said to be lighter, thinner, shorter and smaller, but these trends are being promoted more and more recently due to the spread of surface packages. Furthermore, as the transition of the package form due to the increase in the number of pins and the lowering of thermal resistance accompanying the higher functionality of IC chips, the mainstream is the surface mounting for the purpose of improving the mounting density from the pin-insertion type packages typified by the conventionally diversified DIP. SOJ, SO
It is shifting to surface mount packages such as P and QFP.
In recent years, the fine pitch QFP with a reduced lead pitch has been increased along with the increase in the number of pins, and further the thinning of packages represented by TSOP, TQFP and the like has been progressing.

Most of the multi-pin, narrow-pitch frames are produced by etching. Since etching causes side etching not only in the plate thickness direction but also in the plate width direction, processing of the lead width and the lead interval is performed. The limit depends on the plate thickness, and the thinner the plate thickness, the more advantageous for processing. In addition, due to the demand for thinner package, it is necessary to make the lead frame material thinner. As a result, the plate thickness is 0.15 mm recently.
→ 0.125 mm → 0.10 mm and thin. Such thinning of the lead frame and narrowing of the leads reduce the rigidity of the entire frame and the leads, causing deformation of the inner leads during the assembly process and deformation of the outer leads during device mounting.

The following characteristics are generally required for the lead frame material of such a semiconductor device. (1) The inner lead or the outer lead must have mechanical strength so that it is not easily deformed. (2) It has excellent etchability and press workability in the pattern formation of the lead frame. (3) It has a high thermal conductivity capable of efficiently dissipating the heat of the lead frame. As the power consumption increases as the IC is highly integrated and the number of pins increases, measures to dissipate heat generated are important problems in IC design. Copper alloys are advantageous in terms of heat dissipation because they have properties that far exceed the 42 alloy in thermal conductivity. (4) Excellent electrical characteristics. (5) Excellent solderability in mounting and high reliability of solder joints (6) Excellent Ag plating property for bonding. (7) The copper alloy surface has excellent resistance to thermal oxidation and is resistant to oxidation in the heating step. (8) It has excellent repetitive bendability. (9) The price is appropriate. Although the performance required for the lead frame material of the semiconductor device has been described above, the present invention can also be used as a material for other electronic devices that require similar performance.

However, phosphor bronze, Kovar (trade name) and 42 alloy, which have been conventionally used, have merits and demerits with respect to these various required characteristics, and cannot satisfy all of the above characteristics. It was In particular, considering that the number of lead pins is increasing and the miniaturization is progressing, the shape is becoming more complex and the pins are becoming narrower, and it is necessary to consider the material to have better lead strength, etching property, and bending workability. For example, it has been difficult to say that the conventional material has sufficient performance in these points.

Further, Cu-Cr-Zr type alloys for electronic equipment are known per se. For example, according to Japanese Unexamined Patent Publication No. 5-17789, a semi-continuous casting ingot is hot-rolled to prepare both side surfaces. A method of cold rolling after cutting is adopted.
However, this treatment method does not provide sufficient characteristics.

[0007]

Therefore, the present invention provides Cu-Cr-Zr-based alloys with the excellent electrical characteristics and thermal conductivity of copper-based materials, and at the same time, is sufficient as a lead material for semiconductor devices. Satisfying strength, spring characteristics,
It is an object of the present invention to provide a method for producing a copper alloy that also has etching properties and bending workability.

[0008]

According to the present invention, (a) by weight, Cr: 0.05 to 0.4% and Zr: 0.03 to.
A copper alloy containing 0.25% and the balance Cu and unavoidable impurities, (b) Cr: 0.05 to 0.4
%, Zr: 0.03 to 0.25%, Zn: 0.06 to
A copper alloy containing 2.0% and the balance Cu and unavoidable impurities, or c) Cr: 0.05 to
0.4%, Zr: 0.03-0.25%, and Zn:
0.06 to 2.0%, Ti, Fe, Ni,
One or more of Sn, In, Mn, P, Mg and Si: 0.01 to 1.0% in total is contained, and the balance is Cu.
And a method for producing a high-strength and high-conductivity copper alloy for electronic devices comprising unavoidable impurities, (a) solution treatment by any of the following methods: (a) annealing at a temperature of 700 ° C. or higher, (B) Water cooling performed at a hot rolling finish temperature of 700 ° C. or higher and immediately thereafter at a cooling rate of 100 ° C./min or higher, (b) cold rolling with a workability of 50% or higher, (c) 300 to 700 An electron characterized by sequentially performing steps of aging treatment at a temperature of ℃, (d) cold rolling with a working degree of 30 to 70%, and (e) strain relief annealing at a temperature of 350 to 700 ° C. The present invention relates to a method for producing a high strength and high conductivity copper alloy for equipment. The configuration of the present invention will be described below. First, the composition of the copper alloy of the present invention will be described.

Cr When Cr is aged, the Cr alone precipitates in the parent phase to improve the strength and heat resistance of the alloy, but if the content is less than 0.05%, it precipitates. The desired effect cannot be expected due to insufficient Cr content. On the other hand, when Cr is contained in excess of 0.4%, undissolved Cr remains as Cr phase in the mother phase even after solution treatment. , Present as whisker-like inclusions when the rolled vertical section is etched,
Etchability is significantly impaired. For the above reasons, Cr
The content was set to 0.05 to 0.4%.

Zr Zr has an action of forming a compound with Cu and precipitating in the matrix phase by aging treatment to strengthen this, but if the content is less than 0.03%, the precipitation is insufficient. However, if Zr is contained in excess of 0.25%, undissolved Zr will remain as Zr phase in the matrix even after solution treatment, resulting in poor etching and conductivity. The Zr content is 0.0
It was set to 3 to 0.25%.

Zn Zn is a component that is added as necessary because it has the function of improving the heat-resistant peeling property of solder, but if the content is less than 0.06%, the desired effect due to the above-mentioned action is obtained. However, if the Zn content exceeds 2.0%, the conductivity deteriorates. Therefore, the Zn content is 0.06 to 2.0%.
I decided.

Ti, Fe, Ni, Sn, In, Mn,
Each of P, Mg and Si has the effect of improving the conductivity of the alloy by precipitation strengthening or solid solution strengthening without significantly lowering the conductivity of the alloy. Therefore, if necessary, one or more of them may be added. However, if the total content is less than 0.01%, the desired effect due to the above-described action cannot be obtained, while the total content is less than 0.01%. If the content exceeds 0%, the conductivity and workability of the alloy will be significantly deteriorated. Therefore, Ti, Fe, Ni, Sn, I which are added individually or in the case of two or more kinds are added.
The total content of n, Mn, P, Mg and Si is 0.01
It was determined to be ~ 1.0%. Then, the manufacturing process of the copper alloy of the said composition is demonstrated.

Solution treatment The solution treatment is for solid-solving Cr, Zr, Ti and the like in the matrix to obtain a high-strength material in the subsequent aging treatment and to improve the etching property. When the solution treatment temperature is higher, the amount of solid solution in the matrix of Cr, Zr, Ti or the like increases, the strength after aging becomes higher and the etching property becomes better. Therefore, the solution treatment temperature should be 700 ℃.
High strength is secured by the above. When the cooling rate during the solution treatment is slow, a nonuniform strengthening precipitate of Cr is generated, which causes a decrease in strength and impairs the etching property. Therefore, a high cooling rate is desired.

In the case of the present alloy, the following two methods are possible as the method for carrying out the solution treatment. One of them is a method of using a line for continuously annealing and water-cooling with a plate thickness of preferably about 2 mm or less. In this case, it is necessary to set the annealing temperature to 700 ° C. or more and water-cool from the annealing temperature for the above reason. . The other method is to perform solution treatment by performing water cooling after hot rolling. At this time, it was found that the strength reduction can be suppressed by setting the end temperature of the hot rolling to 700 ° C. or higher for the above reason and immediately followed by water cooling at a cooling rate of 100 ° C./min or higher. In this method, since cold rolling can be performed immediately after hot rolling, the process is shortened, which is advantageous in terms of manufacturing cost. The hardness after the solution treatment is preferably in the range of Hv45 to 90.

Cold Rolling In the present invention, cold rolling is performed after the solution treatment,
High strength is obtained by promoting work hardening and precipitation of precipitates in the subsequent aging step. The first cold rolling is 50
Perform at a processing rate of at least%. The workability of cold rolling is set to 50% or more because if the content is less than 50%, the above-described effect becomes insufficient and desired strength cannot be obtained. The hardness after cold rolling is preferably in the range of Hv 130 to 160.

The aging aging treatment, this in order to improve the strength and conductivity Cu
Required for -Cr-Zr alloys. Aging treatment temperature is 3
The reason why the temperature is set to 00 to 700 ° C is that it is not economical because the aging treatment is time-consuming and is less than 300 ° C, and if it exceeds 700 ° C, Cr and Zr are solid-dissolved, which is a characteristic feature of an age hardening alloy. It is also because conductivity cannot be obtained.
The hardness after the aging treatment is preferably in the range of Hv160 to 200.

Second Cold Rolling In the present invention, cold rolling after aging treatment causes work hardening, and further refines the precipitate formed in the preceding aging treatment to further increase the strength significantly. . At this time, if the workability is 30% or more, no increase in strength is observed at less than 30%, and if the workability is 70% or less, if it exceeds 70%, the final product is bent. This is because rough skin occurs at the bent portion. The hardness after the second cold rolling is preferably in the range of Hv 180 to 220. Further, the workability of the second cold rolling is preferably less than that of the first cold rolling, and is preferably in the range of 30 to 40%.

In the present invention, 350 to 7 are used in the present invention in order to improve the spring property and recover the ductility from the above working and heat treatment conditions.
Strain relief annealing is performed at 00 ° C. Strain relief annealing temperature is 350 ° C to 7
The reason why the temperature is set to 00 ° C. is that sufficient spring properties and ductility cannot be obtained at temperatures lower than 350 ° C., and re-dissolution of precipitates occurs at temperatures higher than 700 ° C., resulting in a marked decrease in strength.

[0019]

As described above, in the present invention, the solution treatment substantially eliminates the undissolved contents of Cr and Zr, and enables the subsequent first cold rolling with a high workability. Next, the aging treatment and the second cold rolling are performed to refine the aging precipitates and obtain a work-hardened state to increase the strength. Finally, the work strain is removed by strain relief annealing.

[0020]

EXAMPLES Next, the effects of the present invention will be described more specifically with reference to examples showing particularly preferable composition ranges. First,
Mainly made of electrolytic copper or oxygen-free copper, copper chromium master alloy, copper zirconium master alloy, zinc, titanium, nickel,
Using tin, indium, manganese, magnesium, and copper-phosphorus master alloys as auxiliary materials, a high-frequency melting furnace is used to melt copper alloys of various composition shown in the tables of FIGS. It was cast into a 30 mm ingot. Next, each of these ingots is subjected to hot working and solution treatment, 1
The cold rolling, aging treatment, final cold rolling, and strain relief annealing of the second time were sequentially performed under the conditions shown in Tables 1 and 2 to obtain a 0.15 mm plate. The solution treatment is performed by the method shown in Tables 1 and 2, of which annealing-water cooling is performed on a plate having a thickness of 1.5 mm, and hot-pressing-water cooling is performed on a plate having a thickness of 8 mm. This is the processing performed for the hot rolling finishing temperature of No.
In the case of hot pressure-water cooling, cold rolling was performed immediately after hot rolling.

Then, various test pieces were sampled from the obtained plate material and a material test was conducted to evaluate the characteristics as a material for electronic equipment. The evaluated properties are strength, elongation, conductivity, etching property, bendability, and solder heat resistance peeling property. The strength and elongation were measured by a tensile test, and the conductivity was determined by the conductivity (% IACS).

Regarding "etching", the liquid temperature is 35.degree.
The etching property was evaluated by making a hole with a width of 10 mm and a length of 10 mm in the sample using 45 ° Baume ferric chloride and observing an etching surface perpendicular to the rolling direction with an SEM. The case where a smooth etching surface was observed was evaluated as ◯, and the case where a projection of 5 μm or more was observed on the etching surface was evaluated as x.

Regarding the bending workability, as shown in FIG. 5, a 10 mm test piece was repeatedly bent at an inner bending radius of 0.4 mm (sheet thickness) at a right angle to the rolling direction and 90 ° on one side until it was broken. The number of times of bending (reciprocating once) was measured. The test was performed with n = 5, and the average value was used for evaluation.

The heat resistance peeling resistance was investigated by plating the material with 5 μm thick solder (90% Sn-10% Pb).
Hold in a high temperature tank at 150 ° C for up to 1000 hours, during which 1
It was taken out every 00 hours and subjected to 90 ° bending reciprocation once to examine the start time of solder peeling. 1000
If the peeling did not occur until the time, the investigation result was "1000.
h ”was displayed.

The results of these investigations are shown in the tables of FIGS.
From the results shown in these tables, the following is clear. That is, all of the alloys 1 to 16 of the present invention are excellent in strength, conductivity, bendability, and stress relaxation characteristics, and sufficiently good evaluations of other characteristics can be obtained.

On the other hand, Comparative Alloy 17 is inferior in strength due to insufficient Cr content, and Comparative Alloy 1
In Nos. 8 and 19, the Zr and Cr contents exceeded the respective upper limits, so that the etching properties and bendability were poor. next,
Since the Zn content of the comparative alloy 20 exceeds the upper limit, the conductivity of the comparative alloy 20 is poor. Comparative alloy 21 is inferior in strength because the solution treatment temperature is lower than the lower limit value, and comparative alloy 22 is low in cooling rate during the solution treatment. Comparative alloy 22
Indicates that the workability after the solution treatment and the workability during the final cold rolling of the comparative alloy 24 are below the lower limit values, and thus the strength is poor. Comparative alloy 24 is an example in which the strength is inferior because the temperature of the stress relief annealing exceeds the upper limit value.

The alloy No. of the example of the present invention was used. 4 Ti
In place of 0.08% Ni, 0.07% In, 0.
0.05 Mn, 0.02% P, 0.05% Mg, 0.
Similar results were obtained when the same heat treatment and processing as those of the alloy 4 of the present invention were performed on the alloys to which 06% of Si was individually added.

[0028]

By adopting the manufacturing method of the present invention, it becomes possible to obtain a copper alloy having good strength, conductivity, etching property and bendability, which greatly contributes to downsizing and thinning of electronic devices. It has an extremely useful effect in industry.

[Brief description of drawings]

FIG. 1 is a table showing the composition and production conditions of the alloy of the present invention.

FIG. 2 is a table showing the composition and manufacturing conditions of comparative alloys.

FIG. 3 is a table showing characteristics of the alloys in Table 1.

FIG. 4 is a table showing the properties of the alloys of Table 2.

FIG. 5 is an explanatory diagram of a bending test method.

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[Procedure amendment]

[Submission date] June 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a chart showing the composition and manufacturing conditions of an alloy of the present invention.

FIG. 2 is a chart showing the composition and production conditions of a comparative alloy.

FIG. 3 is a chart showing the properties of the alloys of Table 1.

FIG. 4 is a chart showing the properties of the alloys of Table 2.

FIG. 5 is an explanatory diagram of a bending test method.

Claims (3)

[Claims] 1. Cr: 0.05-0.4% by weight
And Zr: 0.03 to 0.25% and the balance is Cu and unavoidable impurities in the method for producing a high-strength and high-conductivity copper alloy for electronic devices, comprising: (a) one of the following methods: Solution treatment: (a) annealing at a temperature of 700 ° C. or higher, water cooling from that temperature (b) water-cooling performed at a hot rolling finish temperature of 700 ° C. or higher and immediately thereafter at a cooling rate of 100 ° C./min or higher, (B) cold rolling with a workability of 50% or more, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling with a workability of 30 to 70%, and (e) 350 to 700 ° C. A method for producing a high-strength and high-conductivity copper alloy for electronic equipment, which comprises sequentially performing steps of strain relief annealing at a temperature. 2. A weight ratio of Cr: 0.05 to 0.4.
%, Zr: 0.03 to 0.25%, Zn: 0.06 to
A method for producing a high-strength and high-conductivity copper alloy for electronic devices, which comprises 2.0% and the balance Cu and unavoidable impurities, and (a) solution treatment by any of the following methods: (a) Annealing at a temperature of 700 ° C. or higher, water cooling from the temperature (b) Hot rolling end temperature is 700 ° C. or higher, and immediately after that, water cooling performed at a cooling rate of 100 ° C./min or higher, (b) Working ratio of 50% The above cold rolling, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling at a working ratio of 30 to 70%, and (e) strain relief annealing at a temperature of 350 to 700 ° C., A method for producing a high-strength and high-conductivity copper alloy for electronic equipment, which is characterized by sequentially performing the following steps. 3. A weight ratio of Cr: 0.05 to 0.4.
%, Zr: 0.03 to 0.25%, and Zn: 0.06.
.About.2.0%, further containing Ti, Fe, Ni, Sn, I
One or more of n, Mn, P, Mg and Si: 0.0 in total
In a method for producing a high-strength and high-conductivity copper alloy for electronic devices, which also contains 1 to 1.0%, and the balance being Cu and unavoidable impurities, (a) solution treatment by any of the following methods: (A) Annealing at a temperature of 700 ° C. or higher, water cooling from that temperature (b) Water cooling performed at a hot rolling end temperature of 700 ° C. or higher and immediately thereafter at a cooling rate of 100 ° C./min or higher, (b) processing Cold rolling with a degree of 50% or more, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling with a working degree of 30 to 70%, and (e) strain at a temperature of 350 to 700 ° C. A method for producing a high-strength and high-conductivity copper alloy for electronic devices, which comprises sequentially performing steps of annealing and annealing.