JPH0430465B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing an iron-copper alloy ribbon for high-strength lead frames used in low-cost semiconductor ICs, LSIs, etc., which have excellent thermal and electrical conductivity. (Prior art) As a lead frame material for semiconductor ICs, LSIs, etc., an alloy containing 26 to 30% by weight of nickel and 11 to 16% by weight of cobalt in iron is used, for example, as disclosed in Japanese Patent Application Laid-open No. 59-198741. (Kovar alloy), also JP-A-Sho
The reason is that the thermal expansion properties of iron and alloys containing 30 to 55% by weight of nickel (42% Ni alloy is a typical component) shown in Publication No. 60-111447 match those of glass sealants and Si. It is used. On the other hand, copper
Copper alloys are also increasingly being used in ICs that require high thermal and electrical conductivity. In other words, the Kovar alloy mentioned above and 42Ni
Although alloys have excellent strength and heat resistance, they have poor thermal and electrical conductivity, poor workability, and are expensive. There is a trend toward copper alloys with good conductivity and workability. (Problems to be Solved by the Invention) However, since copper alloys generally have poor heat resistance and strength, for example, CA-195 alloy or the alloy described in JP-A-60-218442 aims to improve these drawbacks. However, the addition of these elements increases the cost of the alloy and also causes problems such as deterioration of thermal and electrical conductivity. The present invention has developed an iron-copper alloy thin film for lead frames that has sufficient thermal and electrical conductivity, high strength, and good workability by adding appropriate amounts of oxygen, silicon, aluminum, and titanium to iron-copper alloys. The purpose is to provide belts. (Means for solving the problems) The present invention overcomes these problems of the prior art,
In order to produce an iron-copper alloy thin strip with excellent properties as a material for lead frames, the inventors conducted extensive research on material improvement using directly cast iron-copper alloy thin slabs, and developed a material for high-strength lead frames. A method for producing iron-copper alloy ribbon was invented. The gist of the present invention is as follows. (1) 20% to 90% by weight of Cu, 0.03% to 0.2% by weight of O, 0.012% to 0.2% by weight of one or more of Si, Al, and Ti each;
Al: 0.015-0.25% by weight, Ti: 0.02-0.3% by weight
Includes in the range of 8/7Si+8/9Al+2/3Ti
is 0.013% by weight or more, (8/7Si+8/9Al+2
100 pieces of iron-copper alloy thin slab with composition containing /3Ti)/O in the range of 1 or less and the balance mainly consisting of Fe.
A method for producing a high-strength iron-copper alloy ribbon for lead frames, which comprises continuous casting at a cooling rate of ℃/second or higher, and then subjecting it to an aging treatment at 450 to 650℃ for 20 minutes or more and 500 minutes or less. . (2) 20% to 90% by weight of Cu, 0.03% to 0.2% by weight of O, 0.012% to 0.2% by weight of each of one or more of Si, Al, and Ti;
Al: 0.015-0.25% by weight, Ti: 0.02-0.3% by weight
Includes in the range of 8/7Si+8/9Al+2/3Ti
is 0.013% by weight or more, (8/7Si+8/9Al+2
100 pieces of iron-copper alloy thin slab with composition containing /3Ti)/O in the range of 1 or less and the balance mainly consisting of Fe.
Continuous casting at a cooling rate of ℃/second or higher, annealing at 650 to 1050℃ for 5 minutes to 60 minutes after cold rolling, and aging treatment at 450 to 650℃ for 20 minutes to 500 minutes. A method for producing iron-copper alloy ribbon for high-strength lead frames. (3) 20% to 90% by weight of Cu, 0.03% to 0.2% by weight of O, 0.012% to 0.2% by weight of each of one or more of Si, Al, and Ti;
Al: 0.015-0.25% by weight, Ti: 0.02-0.3% by weight
Includes in the range of 8/7Si+8/9Al+2/3Ti
is 0.013% by weight or more, (8/7Si+8/9Al+2
100 pieces of iron-copper alloy thin slab with composition containing /3Ti)/O in the range of 1 or less and the balance mainly consisting of Fe.
After continuous casting at a cooling rate of ℃/second or more, after cold rolling, annealing at 650 to 1050℃ for 5 minutes to 60 minutes, and aging treatment at 450 to 650℃ for 20 minutes to 500 minutes. , final cold rolling reduction rate 15~60%
1. A method for producing iron-copper alloy ribbon for high-strength lead frames, characterized by carrying out the following steps. The reasons for limiting this configuration requirement will be explained below. First, the reason for limiting the chemical composition of the alloy is as follows. A higher content of copper is preferable in order to improve thermal and electrical conductivity, but if the application requires strong strength, it is desirable to increase the content of iron. If the copper content is less than 20% by weight, the thermal and electrical conductivity necessary for an IC lead frame cannot be obtained, so this is set as the lower limit. The upper limit is set at 90% by weight because if the iron content is 10% by weight, the distribution of the iron phase, which is effective in refining the structure, will be insufficient, or the upper limit is set to a certain extent to alleviate heat shock during soldering. This is because there are cases where it is preferable to define Next, adding 0.03% by weight or more of oxygen is due to the relationship with the following oxide-forming elements: Si, Al,
This is because it forms oxides with Ti and copper, or with Si, Al, Ti, and iron in copper, exhibiting a dispersion strengthening effect, and improves thermal and electrical conductivity by reducing the amount of these elements in solid solution. . Further, the upper limit is set to 0.2% by weight because at the same time as the above effects are saturated, the deterioration of workability becomes noticeable due to an increase in the amount of oxides. Next, add one or more of Si, Al, and Ti.
Si 0.012-0.2% by weight, Al 0.015-0.25% by weight,
Contains Ti in the range of 0.02-0.3% by weight and 8/7Si+
The reason why 8/9Al + 2/3Ti is added at 0.013% by weight or more is that these are strong oxide-forming elements, and they cause fine oxidation to occur at or immediately after the solidification of the copper-rich phase of the slab. This is because when forming a product, it is extremely effective in preventing a decrease in conductivity due to solid solution elements and increasing the strength of the coil. The amounts of these elements to be added are determined from stoichiometric considerations for oxide formation. Among these limits, the lower limit is the amount necessary for one or more of these oxides to exist finely dispersed in the iron-rich phase and copper-rich phase, and the upper limit is the amount of oxygen and However, since the oxide becomes too coarse and does not contribute to strengthening, it also significantly reduces ductility, so the respective amounts are determined. In addition, it is often useful to add trace amounts of Cr, Zn, Sn, Nb, etc., so they may be added.
There is no particular limitation on this. Other elements are impurity elements that are unavoidably mixed in raw materials, melting, and other processes. Next, the manufacturing process of the present invention will be explained. First, a thin iron-copper alloy slab is produced by continuous casting, but the primary cooling rate at this time is limited to 100° C./second or higher. The reason is that the larger the cooling rate during solidification, the finer the solidified structure becomes.
Even if heat treatment or cold rolling-annealing is performed thereafter, the effect is preserved. The limit is copper in the alloy.
This is because even in cases where it is relatively difficult to obtain a high strength of 70% or more, the value required for a high-strength lead frame material can be obtained. Furthermore, cold rolling and aging treatment are subsequently performed. The main purpose of cold rolling is to obtain the required plate thickness for the lead frame, but the reduction rate of the first cold rolling depends on the combination of chemical composition, casting thickness, and final cold rolling process to achieve the desired plate thickness.・Conditions for obtaining strength and workability. Its effective rolling reduction range is 30-95
%. Aging treatment is essential in the manufacturing process in order to improve thermal and electrical conductivity, and an appropriate temperature should be selected depending on the chemical composition and pre-process conditions.
Generally, if the temperature is too low, distortion will occur around the precipitates, deteriorating the properties of the base material, and increasing heating time, which will limit equipment and manufacturing efficiency. Also, if the temperature is too high, not only will the amount of precipitate decrease and good properties will not be obtained, but the precipitates will also become coarse, which is disadvantageous in terms of ensuring strength, so aging treatment at 450 to 650℃ for 20 minutes to 500 minutes is the appropriate condition. becomes. In addition, if workability is particularly required as a lead frame, annealing is performed at a temperature range of 650 to 1050°C for a practical time of 5 minutes to 60 minutes before aging treatment, which is similar to that introduced during cold rolling. It is possible to improve workability by removing processing strain, recrystallization, and grain growth. The present invention is suitable for use as a lead frame that requires strength, but if further workability and high strength are required, cold rolling is performed at a reduction rate of 15 to 60% after the above annealing to reduce processing strain. Increasing strength by introduction. In this case, the lower limit at which the effect becomes noticeable is 15%, and the upper limit is a reduction rate of 50% at which workability, thermal and electrical conductivity do not decrease significantly. Note that if the steel contains 70% by weight or less of copper, or if the primary cold rolling reduction exceeds 50%, measures must be taken to prevent cracking during cold rolling. Effective methods include slow cooling in a constant temperature range after casting and reheating after cooling to room temperature. The conditions are a temperature range of 850 to 750℃ after casting.
Cool at a cooling rate of 100℃/sec or 850-450℃
Heat treatment is performed at a temperature range of 20 minutes to 60 minutes. Ten
If it is less than 100°C/sec, sufficient cracking prevention effect cannot be obtained, and if it exceeds 100°C/sec, the grains will become coarse or the supersaturation degree obtained by rapid cooling may decrease, which is rather undesirable, so it is limited. This effect is due to preventing the generation of residual austenite or martensite that occurs during cooling after casting, or reducing the hardness difference between iron and copper structures through tempering softening. (Example) The effects of the present invention will be explained below with reference to Examples. Example 1 Table 1 shows the chemical compositions of alloys B to E having the composition range of the present invention and comparative materials A and F having the composition range of comparison.

[Table] Table 2 shows the material properties of the iron-copper alloy ribbon when processed under the following conditions. Continuous casting was carried out using a twin roll casting machine at a cooling rate of 3.5×10 ² /sec to a plate thickness of 2.0 mm. After casting, it was held at 820°C for 30 minutes during cooling to prevent cracking during cold rolling, and then rolled to 0.3 mm at a rolling reduction of 85%. After cold rolling
It was aged at 490°C for 180 minutes and cooled in air. Sample number 1 is an example in which parameter X (see Table 1) is below the lower limit, and both strength and conductivity are insufficient. Sample number 6 is an example in which parameter・Low conductivity. In the table, the characteristics of Fe-Ni and Cu-Fe-Sn alloys are also included for comparison. From this, it is clear that the properties of the material of the present invention are excellent.

【table】

[Table] Example 2 Table 3 compares the case where sample material B having the composition range of the present invention was cast using a twin roll casting machine and the cooling rate was low outside the range of the present invention, with the case of the present invention. Here, the processing conditions after casting are the same as in Example 1. It is clear from this that the cooling rate during casting has a large effect.

[Table] Example 3 Table 4 compares sample material C having the composition range of the present invention with the case of the present invention in which the effect of annealing before aging treatment after cold rolling is not performed. It is clear from this that adding annealing before aging treatment has a significant effect of improving ductility and electrical conductivity.

[Table] Example 4 Table 5 shows sample material D having the composition range of the present invention, which was cold rolled and then annealed at 700°C for 30 minutes, aged at 490°C for 180 minutes, and further subjected to final cold rolling of 25%. Indicates the material when used. It is clear from this that final cold rolling is an effective means of increasing strength without significantly impairing electrical conductivity.

[Table] Example 5 Table 6 shows the plate thickness of test material E having the composition range of the present invention using a twin roll casting machine at a cooling rate of 2.5×10 ³ /sec.
Continuously cast to 0.8mm, with a direct reduction rate of 48% after casting.
After rolling to 0.42mm and cold rolling, aging treatment was performed at 490℃ for 180 minutes, air cooling, and final cold rolling of 30% was performed.
To prevent cracking during cold rolling, the material was held for 30 minutes, then rolled to 0.3 mm at a reduction rate of 85%, and after cold rolling,
A comparison is shown with a material aged at 490℃ for 180 minutes and cooled in air. It can be seen from this that an iron-copper alloy ribbon for lead frames having excellent properties can be produced by either method.

[Table] (Effects of the invention) The present invention makes it possible to obtain a material with excellent strength and thermal and electrical conductivity by using continuously cast thin slabs in the production of iron-copper alloy ribbons for high-strength lead frames. It is an industrially valuable invention that can economically produce a material that can replace conventional Fe-Ni alloys and copper alloys for high-strength lead frames.

Claims (1)

[Claims] 1 Cu: 20% to 90% by weight, O: 0.03% to 0.2% by weight, one or more of Si, Al, and Ti, each containing 0.012% to 0.2% by weight of Si, Al
0.015 to 0.25% by weight, contains Ti in the range of 0.02 to 0.3% by weight, and contains 0.013% by weight or more of 8/7Si + 8/9Al + 2/3Ti, (8/7Si + 8/9Al + 2/3Ti)/O
An iron-copper alloy thin slab with a composition of 1 or less and the balance mainly consisting of Fe is continuously cast at a cooling rate of 100℃/second or more, and after cold rolling, it is heated at 450 to 650℃ for 20
A method for producing a thin iron-copper alloy ribbon for high-strength lead frames, characterized by subjecting it to aging treatment for a period of not less than 500 minutes. 2 Cu from 20% to 90% by weight, O from 0.03% to 0.2% by weight, one or more of Si, Al, and Ti, each from 0.012 to 0.2% by weight, and Al.
0.015 to 0.25% by weight, contains Ti in the range of 0.02 to 0.3% by weight, and contains 0.013% by weight or more of 8/7Si + 8/9Al + 2/3Ti, (8/7Si + 8/9Al + 2/3Ti)/O
A thin iron-copper alloy slab with a composition of 1 or less and the remainder mainly consisting of Fe is continuously cast at a cooling rate of 100℃/second or more, and after cold rolling at 650 to 1050℃ for 5 minutes or more and 60 minutes. Perform the following annealing at 450-650℃ for 20
A method for producing a thin iron-copper alloy ribbon for high-strength lead frames, characterized by subjecting it to aging treatment for a period of not less than 500 minutes. 3 Cu from 20% to 90% by weight, O from 0.03% to 0.2% by weight, one or more of Si, Al, and Ti, each from 0.012 to 0.2% by weight, and Al.
0.015 to 0.25% by weight, contains Ti in the range of 0.02 to 0.3% by weight, and contains 0.013% by weight or more of 8/7Si + 8/9Al + 2/3Ti, (8/7Si + 8/9Al + 2/3Ti)/O
A thin iron-copper alloy slab with a composition of 1 or less and the remainder mainly consisting of Fe is continuously cast at a cooling rate of 100℃/second or more, and after cold rolling at 650 to 1050℃ for 5 minutes or more and 60 minutes. Perform the following annealing at 450-650℃ for 20
A method for producing a high-strength iron-copper alloy ribbon for lead frames, which comprises performing an aging treatment for at least 500 minutes, followed by final cold rolling at a rolling reduction ratio of 15 to 60%.