JPH0397831A - Fe-ni alloy excellent in etching workability and its production - Google Patents

Abstract

PURPOSE:To easily reduce C content and to improve etching workability by repeatedly applying cold rolling and softening to a hot rolled stock of Fe-Ni alloy and applying high crystal anisotropy by means of finish rolling. CONSTITUTION:A hot rolled stock having a composition consisting of, by weight, 30-60% Ni (or 25-40% Ni and 5-20% Co), <=0.25% Si, <=0.50% Mn, and the balance Fe is subjected to a repetition of cold rolling and softening once or more. Subsequently, the resulting cold rolled stock is subjected to cold rolling at >=60% draft and to softening. Then, finish rolling is performed to a product sheet thickness at <=50% draft, by which high crystal anisotropy is provided. By this method, the Fe-Ni alloy having <=0.002wt.% C among impurities, having >=50% intensity in a (200) plane in the relative X-ray intensity of a crystal plane by means of X-ray diffraction, and excellent in etching workability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an Fe--Ni alloy that has excellent etching processability and is used for lead frames or shadow mask materials of integrated circuit elements.

[Conventional technology]

Fe is a material for lead frames of integrated circuit elements.
-42%Ni, Fe-50%Ni, etc.
Fe-29N i-17Co alloy (Kovar) etc.
-Ni alloy is used.

In recent years, as integrated circuit devices have become highly integrated, leads have become extremely multi-bin (lead) and have become more complex.
Etching processing, which was mainly used for 4-bin class, is also available from 160~
It has become possible to manufacture products with 240 bins and even super large numbers of bins with more than 240 bins.

As a result, the spacing between the lead frames, especially the inner leads, has to become extremely narrow.Etching processing, which did not pose any problems with conventional lead spacing, has become a problem with these multi-bin lead frames. This is beginning to occur.

Further, even in shadow masks using so-called impur alloys based on Fe-36%Ni, finer etching processing is required due to higher definition.

For this reason, there is a need for lead frame materials and shadow mask materials that are superior in etching processability by several steps compared to conventional materials.

[Problem to be solved by the invention]

With conventional Fe-Ni alloys, the etching processability of the aforementioned 240-pin class multi-bin lead frame is not fully satisfactory, and inner leads may stick together, and lead frame size and shape standards may not be met. There were problems such as not being able to satisfy the following. Regarding the improvement of etching processability, JP-A-61-82
No. 453 reports that it is possible to improve etching processability by regulating the C content to 0.01% or less, and in JP-A-61-84356, it is possible to improve etching processability by further regulating non-metallic inclusions. has been completed.

However, the current situation is that there is a demand for alloys with even better etching processability in the etching process of ultra-high-bin lead frames and high-definition shadow masks. On the other hand, the C content is set to the level disclosed in JP-A-61-82453 or JP-A-61-8435.6 (
0.004%, 0. 007%) is not easy to reduce on an industrial production scale. In view of the above points, the present invention mainly reduces the C content to a level that is difficult to achieve with ordinary steel melting methods, and is fully compatible with etching processes such as ultra-bin lead frames and high-definition shadow masks. , F e- with excellent etching processability
The purpose is to provide a Ni-based alloy and a method for producing the same. [Means for Solving the Problem] The present inventor conducted experiments focusing on carbon content, crystal grain size of material, amount of nonmetallic inclusions, and rolling and annealing conditions as factors that improve etching processability. I did it. The results will be explained.

As mentioned above, in normal melting and refining methods, C
The limit is to reduce the C content to about 0.003%, and in order to reduce the C content below that by refining,
There is a drawback that the cost is extremely high due to the long refining time.

Therefore, in the present invention, it was discovered that by performing decarburization treatment, it was possible to achieve a C content at an unprecedentedly low level, and an etching processability evaluation test was conducted.

Figure 1 shows the relationship between C content and etching rate in Fe-4.2%Ni alloy and Fe-36%Ni alloy in an etching process test using ferric chloride.
It was found that when the C content is 0.002% by weight or less, the etching rate is more than twice that when the C content is about 0.007% by weight, and the etching processability is extremely improved. Note that the Kovar alloy, which is a Fe-Ni-C:o-based alloy, showed almost the same tendency as the Fe-42%Ni alloy.

Regarding the grain size, the JIS grain size number is No.
．． If it is less than 8.0, the surface roughness of the etched cross section becomes large, and the dimensional accuracy during etching becomes unsatisfactory for ultra-bin lead frames. Also, no
．． When the grain size exceeds 8.0, the etching rate increases and etching processability improves. From the above points, the grain size is determined to be No. It is recommended that the score be 8.0 or higher. A more desirable value of grain size is No. It is 9.0 or more. Next, we learned the following from experiments regarding rolling and annealing conditions.

Fe-Ni alloys targeted by the present invention, such as Fe-42%Ni alloy, Fe-36%Ni alloy, and Fe-Ni-Co alloy (copal alloy), can be determined by XA ray diffraction ( Diffraction of the (311), (220), (200), and (111) planes is obtained, and the degree of aggregation of crystal orientations can be determined from the relative X-ray intensity of each. This crystal orientation changes depending on processing conditions.

Figure 2 shows the relative X-ray intensity of each diffraction plane when the degree of rolling was changed and then annealed at 950°C for 5 minutes. At the same time, the strength of the (220) plane increases in the rolled state, and on the contrary, the strength of the (200) plane increases in the subsequent annealed state. Furthermore, it can be seen that the strength of the (200) plane after annealing increases rapidly when the degree of rolling is 60% or more.

The diffraction intensity of the (200) plane after annealing decreases as the (220) plane rises due to the finish rolling, as seen in the change in relative X-ray intensity in the rolled state in Figure 2, due to the subsequent finish rolling. , in the final state, there is (20
0) surface diffraction intensity.

If the strength of this (200) plane is less than 50%, (22
0) plane is in a state where the strength is high and the crystal orientation is isotropic, and a sufficient improvement in etching performance cannot be expected, and on the contrary, (2
It has been found that when the strength of the 00) plane is 50% or more, good crystal anisotropy is imparted and improvement in etching performance is achieved.

Based on the above knowledge, the present invention has been developed to improve etching workability that exceeds that of conventional Fe-Ni alloys by regulating the C content to an unprecedentedly low level and by specifying the crystal grain size and crystal orientation. It is an attempt to obtain.

Specifically, it consists of 30 to 60% by weight of Ni, 0.25% by weight or less of Si, 0.50% by weight or less of Mn, and the balance is Fe and impurities, and the C content of the impurities is 0.002% by weight or less. Fe-Ni alloy with excellent etching processability, Ni 25-40% by weight, Co 5
-20% by weight, Si 0.25% by weight or less, Mn 0.5
Based on a Fe-Ni alloy with excellent etching processability, which is characterized by having a C content of 0.002% by weight or less, with the remainder being Fe and impurities, and xNA diffraction. According to the relative X-ray intensity of crystal planes, the intensity of the (200) plane is 50% or more, and the crystal grain size is No. F with excellent etching processability of 8.0 or higher
It is an e-Ni alloy.

The most significant feature of the present invention is that it has achieved a C content of 0.002% or less, a level that could not be easily obtained in the past.

In other words, in normal melting and refining methods, the limit is to reduce the C content to about 0.003%, and in order to reduce the C content to a lower level by refining, it is necessary to increase the refining time, etc. The disadvantage is that the cost is extremely high. In the present invention, in order to achieve an extremely low C content of 0.002% or less, the C content is reduced to a certain level by melting and refining, specifically to 0.005% or less, and then hot-rolled. By heating and decarburizing a hot rolled material in an atmosphere with a dew point in the range of 110°C to 40°C, the C content can be significantly reduced compared to normal conditions.

Here, the reason why the C content is reduced to 0.005% or less by melting and refining is that if it exceeds this, even if decarburization treatment is performed by heating in an atmosphere with a dew point in the range of -10℃ to 40℃, This is because it is difficult to achieve an extremely low C content of .002% or less.

In addition, the heating atmosphere for decarburization treatment has a dew point of -10
If the temperature is below ℃, decarburization will not be sufficient, and if the temperature exceeds 40℃, sufficient decarburization will occur, but oxidation of the material surface will become noticeable, deteriorating plating and soldering properties. It is necessary to Furthermore, the heating temperature is desirably 700°C or higher since decarburization is insufficient at temperatures below 700°C. More preferably, the temperature is 900°C or higher.

In the present invention, an alloy in which the strength of the (200) plane is 50% or more in the relative X-ray intensity of the crystal planes determined by X-ray diffraction is obtained by repeating cold rolling and softening annealing at least once each on a hot-rolled material. After that, cold rolling is performed with a working degree of 60% or more, followed by softening annealing, and then finish rolling is performed with a working degree of 50% or less to give the material strong crystal anisotropy. It can be manufactured by In this manufacturing method, if the degree of cold rolling before finishing to the product plate thickness is less than 60%, sufficient crystal anisotropy cannot be imparted during the subsequent annealing, and no improvement in etching properties can be expected. For this reason, the degree of cold rolling before finishing was increased to 6.
It needs to be 0% or more. More desirably, the working ratio should be 70% or more. Regarding the annealing conditions, crystal anisotropy can be obtained if the annealing temperature is higher than the recrystallization temperature, but from the point of view of obtaining uniform crystal anisotropy, 70% or more is preferable.
A temperature of 0°C or higher is desirable.

In addition, the finish rolling degree needs to be 50χ or less because the strength of the (220) plane will increase if the degree of finishing exceeds 50%, and the crystal anisotropy with high strength of the (200) plane will not be imparted. .

In the alloy of the present invention, the etching properties can be further improved by controlling the impurity elements as follows.

Si: 0.25% by weight or less Mn: 0.50% by weight or less P: 0.005% by weight or less S: 0.005% by weight or less Other impurity elements: 0.10% by weight or less Regarding impurity elements, Si% If the total content of Mn, P% S and other impurity elements exceeds the above-mentioned value, it will particularly hinder the uniform etching rate. Note that the more desirable range of impurities is as follows.

Si: 0.15% by weight or less Mn: 0.30% by weight or less P: 0.003% by weight or less S: 0.003% by weight or less Other impurity elements: 0.08% by weight or less [Example] Hereinafter, the present invention will be explained based on examples.

Fe-36%Ni alloy, F
An e-42% Ni alloy, an Fe-50% Ni alloy, and an Fe-29 Ni-17 Co alloy were selected, and the chemical composition, relative X-ray intensity of the (200) plane, and A material with a grain size was prepared. Relative xII
Regarding the strength, each X-ray strength was obtained by varying the finish rolling and the degree of cold rolling during finish rolling as described above. Further, the C content of 0.002% or less was obtained by reducing the carbon content to 0.005% by vacuum induction melting, and then heating and decarburizing the steel at 950°C in an atmosphere with a dew point of 20°C after cold rolling. Next, in order to evaluate the etching processability, a circle with a diameter of 0.8 mm was placed on the test piece in a ferric chloride solution (FeC) as shown in Figure 3.
1.: 30%, H, O: remainder) from one side to 10%
Etching was performed for a minute, and the etching depth (h) was measured by the distance traveled by the focal point of an optical microscope using the criteria shown in Figure 3 to determine the etching rate. The results are summarized in Table 1.

Etching processability is evaluated by etching speed: good is marked O, slightly unsatisfactory is marked Δ, and unsatisfactory is marked ×
It is shown in Table 1 with a mark.

As shown in Table 1, the alloy of the present invention, that is, the C content is 0.002% or less, the relative X-ray intensity of the (200) plane is 50% or more, and the grain size is No. When it is 8.0 or more, excellent etching processability is obtained.

〔Effect of the invention〕

According to the present invention, Fe-
Ni-based alloys can be obtained, making it possible to perform high-precision etching processing of high-definition shadow masks for multi-bin or ultra-multi-bin lead frames of integrated circuit devices, thereby achieving improvements in quality, yield, and processing efficiency.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between etching rate and C content in Fe-42Ni alloy, and Figures 2 and 3 are explanatory diagrams of the etching workability test adopted in this example. be. C signal No. 1 C'/. ) 3rd

Claims (1)

[Claims] 1 30 to 60% by weight of Ni, 0.25% by weight or less of Si,
Fe-N with excellent etching processability, consisting of 0.50% by weight or less of Mn, the remainder Fe and impurities, and the C content of the impurities being 0.002% by weight or less
i-based alloy. 2 Ni25-40% by weight, Co5-20% by weight, Si
0.25% by weight or less, Mn 0.50% by weight or less, balance F
e and impurities, and the C content of the impurities is 0.
An Fe-Ni alloy with excellent etching processability characterized by a content of 0.002% by weight or less. 3 In the relative X-ray intensity of the crystal plane by X-ray diffraction (2
3. The Fe-Ni alloy having excellent etching processability according to claim 1 or 2, wherein the strength of the 00) plane is 50% or more. 4 Grain size is No. 3. The Fe-Ni alloy having excellent etching processability according to claim 1 or 2, wherein the Fe--Ni alloy has a molecular weight of 8.0 or more. 5 Grain size is No. 8.0 or higher, the intensity of the (200) plane is 50% in the relative X-ray intensity of crystal planes determined by X-ray diffraction
The Fe-Ni alloy having excellent etching processability according to claim 1 or 2, which is as described above. 6. Excellent etching processability according to any one of claims 1 to 5, wherein the total content of P is 0.005% by weight or less, S is 0.005% by weight or less, and the total content of other impurity elements is 0.10% by weight or less. Fe-Ni alloy. 7. The method for producing an alloy according to claim 3 or claim 5, which comprises repeating cold rolling and softening annealing at least once each on the hot rolled material, and then cold rolling with a workability of 60% or more. Fe with excellent etching processability, which is characterized by imparting strong crystal anisotropy to the material by performing a softening annealing process, followed by a finish rolling process with a workability of 50% or less to the product plate thickness. - A method for producing a Ni-based alloy. 8. A method for producing an alloy according to any one of claims 1 to 6, wherein a material having a C content of 0.005% or less is desorbed in an atmosphere with a dew point in the range of -10°C to 40°C. A method for producing a Fe-Ni alloy with excellent etching processability, which comprises carbon treatment.