JP2006097073A - METHOD FOR PRODUCING Fe-Ni BASED ALLOY THIN SHEET - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an Fe-Ni based alloy thin sheet which can solve the problem particularly on heating shrinkage, can realize excellent flatness even in the case of a wide width of ≥60 mm for example, and is used as the stock for a lead frame, the stock for a lead or the like. <P>SOLUTION: In the method for producing an Fe-Ni based alloy thin sheet, after final cold rolling, straightening by a leveler is performed, stress relieving annealing by a continuous annealing furnace is performed subsequently to the straightening by the leveler, and thereafter, thread coiling-slit processing is performed. Preferably, the stress relieving annealing by the continuous annealing furnace is performed at a furnace tension of ≤20 N/mm<SP>2</SP>, and, more preferably, the stress relieving annealing is performed at 400 to 750°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an Fe—Ni-based alloy thin plate material used for a lead frame material, a lead material, or the like.

For example, various proposals for producing a lead frame made of Fe-Ni alloy thin plate have been made to date. Among these, as proposals paying attention to heat shrinkage and residual stress, there are JP-A-5-109960 (Patent Document 1) and JP-A-6-14581 (Patent Document 2).
The manufacturing method disclosed in JP-A-5-109960 is as follows:
(1) Cold rolling the Fe—Ni alloy and Fe—Ni—Co alloy to the product sheet thickness,
(2) Then slit the product width,
(3) Further, in the step of performing strain relief annealing after the slit processing, a process of heating at 600 to 700 ° C. for 1 to 3 minutes is performed with a tension of 5 kg / mm ² or less (preferably 2 kg / mm ² or less).
This process is disclosed.

In addition, the manufacturing method disclosed in Japanese Patent Laid-Open No. 6-14581 (1) performs hot rolling of a Fe—Ni alloy plate material which has been performed before that.
(2) Next, cold rolling is performed.
(3) Further, soft annealing is performed once.
(4) Next, finish rolling is performed at a workability of 50% or less.
(5) Next, a band material is manufactured by shearing (slit processing) to a predetermined width.
(6) Then, in order to remove distortion caused by the slit processing, strain relief annealing is performed at 600 ° C. or lower.
For the process
(1) Perform finish rolling,
(2) After that slit processing,
(3) Perform sufficient strain relief annealing in the range of 630 to 700 ° C. for the slit processing,
(4) The process of performing leveler correction after that is disclosed.

JP-A-5-109960 Japanese Patent Laid-Open No. 6-145811

As described above, the conventional method is to perform strain relief annealing after slitting the steel strip. This manufacturing method has the following problems.
The technical idea of the conventional manufacturing method is to finally reduce the slit strain and the cold rolling strain by heat treatment. However, in the case of heat treatment after slitting to the product width, as the strain is released, waviness-like undulating deformation is generated and flatness is deteriorated.
In addition, if the material after slitting to the product width is subjected to heat treatment at the same time, the tension of each strip varies, stable control is difficult, and the problem of deformation and damage can be avoided by meandering the material in the furnace. Absent. The heat treatment by one line does not cause a problem of tension control or meandering, but the productivity is greatly reduced.
In other words, the conventional strain relief annealing after slit can reduce the slit strain by heat treatment, but cannot ensure the stable heat shrinkage by the stable tension control and the flatness necessary for the lead frame material. There is the biggest drawback.

In Japanese Patent Application Laid-Open No. 6-14581, leveler correction is performed to ensure flatness after this. However, as described above, the heat shrinkage cannot be stably suppressed, and the product is also corrected by leveler correction at a portion deformed by heat treatment. In the steel strip after the slit to the width, the stress remains locally, and there is a risk of deformation after punching or etching for forming a lead frame.
For example, in the case of a lead frame material, if it is a narrow width of about 30 mm or less as in the prior art, it can be used even if a slight swell occurs, but the board width has increased due to the recent increase in IC efficiency. When the thickness is 60 mm or more, the demand for flatness is severe, and it is very difficult to ensure flatness with the conventional manufacturing method.
The object of the present invention is to solve the problem of heat shrinkage in particular. For example, Fe-Ni alloy thin films used for lead frame materials and lead materials that can realize excellent flatness even with a wide width of 60 mm or more. It is providing the manufacturing method of a board | plate material.

The present invention has been made in view of the above-described problems.
That is, the present invention provides a method for manufacturing a Fe-Ni alloy sheet material, which is subjected to straightening by a leveler after the final cold rolling, and after straightening by the continuous annealing furnace after straightening by the leveler, a slit for slitting. It is a manufacturing method of the Fe-Ni type alloy sheet material which processes.
Preferably, the strain relief annealing by the continuous annealing furnace is a method for producing an Fe—Ni-based alloy sheet material that is performed with an in-furnace tension of 20 N / mm ² or less.
More preferably, the above-described strain relief annealing is a method for producing a Fe—Ni alloy sheet material performed at a temperature of 400 to 750 ° C.
Further, in the present invention, the slitting slit processing is performed in cooperation with the circular upper blade cutter and the circular lower blade cutter, and the diameter of each cutter has a diameter of 750 times or more the thickness of the Fe-Ni alloy thin plate material. Those are preferred.
A more preferred slitting process is a method for producing an Fe—Ni alloy thin plate material in which the overlap amount of the circular upper blade cutter and the circular lower blade cutter is 5 to 50% of the plate thickness.
The preferable composition of the Fe—Ni-based alloy sheet material of the present invention includes C: 0.1% or less, Si: 1.0% or less, Mn: 1.2% or less, and Ni: 30 to 50% by mass%. The balance is substantially Fe.

  By applying the manufacturing method of the present invention, it is possible to more reliably solve the problem of heat shrinkage and obtain an Fe—Ni alloy thin plate having excellent flatness. Fe-Ni-based alloy thin plate material used for materials for manufacturing can be easily obtained

The reason for limitation defined in the present invention will be described in detail below.
In the present invention, the shape is corrected by a leveler after the final cold rolling, the shape of the Fe-Ni alloy thin plate material used for the lead frame material, the lead material, etc. is corrected to ensure flatness, and then continuous annealing is performed. Performs strain relief annealing in a furnace.
The leveler referred to in the present invention means a facility that applies a certain amount of tensile stress to the entire width of the steel strip to correct the length difference generated in the steel strip, and the leveler actually used in the present invention is as follows. In consideration of the thickness of the Fe—Ni alloy sheet material, it is preferable to use a tension leveler, or a leveler in which bending and tension are combined. Tension may be in the range of 50~500N / mm ^2.
In addition, with regard to strain relief annealing, in the manufacturing method of the present invention, since it is before slitting to the product width, for example, a strain by a continuous annealing furnace is applied to a wide width Fe—Ni alloy sheet material of 300 mm to 1200 mm. Can be annealed. Thereby, since only the own weight is loaded on the full width of the steel strip of the Fe—Ni-based alloy sheet material, the tension can be easily adjusted as compared with the case where a narrow strip of steel strip is simultaneously passed.
For this reason, it is possible to suppress the occurrence of partial thermal shrinkage in the Fe—Ni-based alloy thin plate material as in the prior art, and to obtain a stable thermal shrinkage characteristic. Further, as compared with the case where multiple sheets of Fe—Ni alloy thin plate material are passed simultaneously, the meandering of the material can be easily controlled, and the potential for deformation and damage can be eliminated.

The typical continuous annealing furnace used in the present invention includes a vertical type and a horizontal type, and in either case, the tension can be adjusted, and the advantage that the production efficiency can be improved is obtained.
At this time, particularly when a vertical continuous annealing furnace is used, since the longitudinal direction of the steel strip is up and down, slackness of the steel strip can be suppressed, and more stable heat shrinkage characteristics can be obtained.

In the above-described strain relief annealing, it is preferable that the furnace tension is 20 N / mm ² or less. Within this range, thermal shrinkage that occurs during intermediate heat treatment used in press punching or during heating that is received during semiconductor package manufacture can be suppressed to a low level, and problems due to dimensional variations can be prevented. Such an effect can be obtained more reliably.
If the in-furnace tension exceeds 20 N / mm ² , for example, if the intermediate heat treatment is performed by press punching, thermal shrinkage increases, and defects due to dimensional variations are likely to occur, so the in-furnace tension is 20 N / mm ² or less. Stipulated.
There is a slight difference in the lower limit depending on whether the continuous annealing furnace used is a vertical furnace or a horizontal furnace. For example, in the case of a vertical furnace, no special tension is applied, even in a state where it is hung by its own weight. good, consider a shaft furnace stability of the work may be a horizontal furnace together 0.5 N / mm ² and a lower limit, preferably the above effects more reliably be in the range of 1~15N / mm ² Obtainable.

The strain relief annealing is preferably performed at a temperature of 400 to 750 ° C.
Within this temperature range, the effect of relaxation of strain introduced during cold rolling and shape correction can be obtained. A preferred temperature range is 500-700 ° C. The processing time is not particularly specified but may be 10 to 120 seconds.
In addition, the atmosphere at this time may be performed in a reducing atmosphere having a dew point of −70 to −5 ° C., or in an inert gas atmosphere such as nitrogen. Which atmosphere should be selected according to the required characteristics, for example, when it is important to mainly improve the corrosion resistance, it is advantageous to perform in an inert gas atmosphere, in the case of a reducing atmosphere Can mainly impart the effect of suppressing surface oxidation.

In the present invention, after performing the above-described strain relief annealing, for example, a slitting process is performed on the product width.
In the present invention, since both flatness and heat shrinkage characteristics are realized before the slitting slit processing, it is desirable not to give excessive distortion in the slitting slit processing, and the slitting slit can be formed with low distortion. If it is a method, it may be a laser, for example, but it is easy to slit by cooperation of a circular upper blade cutter and a circular lower blade cutter.
The cutter diameters of the circular upper blade cutter and the circular lower blade cutter to be slit are preferably 750 times or more the thickness of the Fe-Ni alloy thin plate material. This is because in the case of a cutter diameter with a diameter less than 750 times the plate thickness, the shear angle becomes large and the residual strain at the time of the slitting slit may increase.
Therefore, in the present invention, in order to greatly reduce the slit distortion, the diameter of the circular upper blade cutter and the circular lower blade cutter are set to a diameter of 750 times or more the thickness of the Fe—Ni alloy thin plate material. 900 times or more is preferable.
At this time, in order to further reduce slit distortion, the overlap amount of the circular upper blade cutter and the circular lower blade cutter is preferably 5 to 50% of the plate thickness. Increasing the overlap amount increases the shear angle and increases the residual strain at the time of slitting. This is because if the amount of overlap is too small, it will not be able to cut completely, resulting in a slit failure.

The Fe—Ni-based alloy referred to in the present invention refers to an alloy composed mainly of Fe and Ni, and the typical composition is mass% and the Ni content is 27 to 52 mass% —the balance being substantially the same. An alloy containing Fe and Ni as main components, such as an alloy of Fe, or an alloy containing 7% or less of Cr, or an alloy obtained by replacing Ni with 20% or less of Co.
Of these, an alloy composed of Fe and Ni is preferable, and the range of preferable elements and the reason thereof will be described below.
C: 0.1% or less C is an element that deteriorates the etching property in Fe-Ni alloy thin plate material that may be subjected to etching. Therefore, the upper limit of C is set to 0.1% or less. A preferable upper limit of C is 0.3%.
Si: 1.0% or less, Mn: 1.2% or less Si and Mn are usually contained in small amounts for the purpose of deoxidation in Fe-Ni alloys, but segregation is likely to occur if excessively added. , Si: 1.0% or less, Mn: 1.2% or less.

Ni: 30-50%
Ni is an element that has an effect of adjusting a thermal expansion coefficient when an Fe—Ni-based alloy thin plate material is used as a lead frame, for example, and has a great influence on low thermal expansion characteristics. If the content is less than 30% or exceeds 50%, the effect of lowering the thermal expansion coefficient is lost, so the range of Ni is 30 to 50%. Preferably it is 40 to 45%.
The balance is substantially Fe
The elements other than the above elements are substantially Fe, but impurities inevitably contained in production are included. Further, in order to improve the press punchability, 0.005% to 0.020% of a free-cutting element such as S may be contained, and an element such as B that improves the hot workability is set to 0.005%. You may make it contain 0005-0.0050%.

The following examples further illustrate the present invention.
Vacuum melting, forging, and hot rolling were performed to produce a cold-rolled Fe-Ni alloy thin plate material used for a lead frame. Next, the Fe—Ni alloy thin sheet material for cold rolling is repeatedly annealed and cold rolled in a reducing atmosphere to obtain a Fe—Ni alloy thin sheet material having a thickness of 0.125 mm and a width of 700 mm. Was made. The annealing temperature was 950 ° C., the final cold rolling was a reduction rate of 25%, and the leveler was a tension leveler with a tension of 200 to 400 N / mm ² .
Further, an Fe—Ni alloy thin plate material for a lead frame material was finished using the Fe—Ni alloy thin plate material by the method of the present invention and the conventional method. The slitting slitting was performed in cooperation with a circular upper blade cutter and a circular lower blade cutter, and the slit widths were all 100 mm.
In addition, about a comparative example, it becomes the annealing after a winding slit. Step No. 7 and no. For No. 8, three strips were simultaneously subjected to strain relief annealing. No. 9 was annealed one by one.
The chemical composition is shown in Table 1, and the production conditions are shown in Table 2.

The heat shrinkage amount of the Fe—Ni alloy thin plate material for the lead frame material after the slitting slit manufactured under each manufacturing condition was evaluated.
The heat shrinkage is evaluated by measuring a distance with a tool microscope by placing a mark at a distance of 180 mm in the rolling direction. After heating the sample at 650 ° C. × 10 minutes (in hydrogen), the gauge point was again measured with a tool microscope, the amount of shrinkage was determined, and divided by the gauge distance before heating and multiplied by 100.
As shown in FIG. 1, the slit strain amount is cut by wire cutting (4) to a width of 1.5 mm from the slit edge (2) of the Fe-Ni alloy thin plate material (1) for the lead frame material. The Fe—Ni alloy thin plate material (1) for the later lead frame material was placed on the surface plate (3), and the lift of the tip was measured with a scale.
The flatness was evaluated by measuring the maximum flying height (mm) with a laser distance sensor after cutting it to a length of 500 mm and placing it on a surface plate.
These measurements were carried out on six striped Fe-Ni alloy thin plate materials for lead frame materials. Table 3 shows the measurement results.

As shown in Table 3, the Fe-Ni-based alloy thin plate material for lead frame material implemented under the strain relief annealing conditions in the manufacturing method of the present invention has a small heat shrinkage of 0.03% or less. .
In the strain relief annealing after slit of the comparative example, No. 7, the shrinkage is high. This is because the tension during strain relief annealing is high and strain is introduced again by the leveler.
No. In some cases, the amount of heat shrinkage is 0.03% or less, but the variation between lots is large. This is because the tension control cannot be controlled independently for each strip because of the multiple strips.
No. In No. 9, since the strips are passed through one line by strain relief annealing, the variation between lots is relatively small, but the strain is released due to strain relief annealing after the slit, and the flatness is deteriorated.
Also in the measurement of the slit strain, the Fe-Ni alloy thin plate material for lead frames made under the slit conditions in the manufacturing method of the present invention has a slit strain amount as small as 15 mm or less.
Regarding the flatness, according to the method of the present invention, a flatness of 0.2 mm or less is realized with respect to a width of 100 mm. However, in the comparative example, the flatness is 0.27 to 0.58 mm. This is because a wavy shape is easily generated because there is no surrounding constraint when the strain is released by each strip for heat treatment after the slit. In particular, in a wide material such as a plate width of 100 mm this time, a remarkable difference appears in flatness.

  Since the present invention is excellent in the characteristics of low heat shrinkage and low slit strain, it can be applied to applications using an Fe—Ni-based alloy sheet material in which fine processing is indispensable.

It is a schematic diagram of the upper surface and side surface which shows a slit distortion measuring method.

Explanation of symbols

1. Fe-Ni alloy thin plate material2. 2. Slit edge Surface plate 4. Notch

Claims (6)

In the manufacturing method of the Fe-Ni alloy thin sheet material, after the final cold rolling, the leveler is corrected, and after the leveler is corrected, the straightening annealing is performed by a continuous annealing furnace, and then the slitting slit process is performed. A method for producing a Fe-Ni alloy thin sheet material, which is characterized. The method for producing a Fe—Ni alloy thin sheet material, wherein the strain relief annealing by the continuous annealing furnace is performed at a furnace internal tension of 20 N / mm ² or less. 3. The method for producing an Fe—Ni-based alloy sheet according to claim 1, wherein the strain relief annealing is performed at a temperature of 400 to 750 ° C. The slitting slitting is performed in cooperation with a circular upper blade cutter and a circular lower blade cutter, and each cutter diameter has a diameter of 750 times or more of the thickness of the Fe-Ni alloy thin plate material. The manufacturing method of the Fe-Ni type alloy sheet material in any one of Claims 1 thru | or 3. The Fe-Ni alloy according to any one of claims 1 to 4, wherein in the slitting slitting, the overlap amount of the circular upper blade cutter and the circular lower blade cutter is 5 to 50% of the plate thickness. Manufacturing method of thin plate material. The Fe—Ni alloy sheet material contains C: 0.1% or less, Si: 1.0% or less, Mn: 1.2% or less, Ni: 30 to 50% in mass%, and the balance is substantial. The method for producing an Fe—Ni-based alloy sheet material according to claim 1, wherein Fe is made of Fe.

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