JP2812869B2 - Plate material for electrical and electronic parts for half-etching and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate material for a half-etched electric / electronic component having one surface half-etched and a method of manufacturing the same, and more particularly, to a lead frame material having a half-etched island portion. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suitable half-etching plate member for electric and electronic parts and a method for producing the same.

[0002]

2. Description of the Related Art Metal or alloy tapes, plates or strips (hereinafter referred to as plate strips) for electric and electronic parts such as IC lead frames are usually manufactured by rolling. The flat plate material for the IC lead frame is required to have flatness in order to avoid occurrence of a defect in a wire bonding step or the like. For this reason, conventionally, in the manufacturing process of the plate material for an IC lead frame, there is provided a process of correcting the distortion by passing the plate material formed by rolling through a tension leveler (Japanese Patent Application Laid-Open No. 4-94815). . In this case, low-temperature annealing may be performed before and / or after the tension leveler step in order to more reliably remove the residual stress. The IC lead frame is manufactured by cutting the plate material having the strain corrected in this manner into a predetermined width, and then forming the plate into a predetermined shape by etching. In addition, processing such as degreasing, pickling, and polishing is appropriately performed before the final rolled material is formed into a lead frame.

[0003]

However, the conventional strips for electric and electronic parts manufactured by the above-described method have the following problems. In other words, in recent years, in order to improve the adhesion between the island portion of the lead frame and the sealing resin, and to increase the surface area of the island portion to improve heat dissipation, the island portion has a surface opposite to the semiconductor chip mounting surface. May be subjected to half-etching to form a large number of minute concave portions (dimples). In this case, the conventional lead frame strip has a small residual stress in the cross section perpendicular to the rolling direction, which is not a problem. However, the residual stress is large in a cross section parallel to the rolling direction. And warping is a problem. FIG. 8 is a schematic diagram showing a residual stress distribution in a thickness direction in a cross section parallel to the rolling direction of a conventional lead frame plate or strip. As shown in FIG. 8, the sum (absolute value) of the tensile stress (positive value) remaining at the center in the thickness direction of the plate strip 11 and the compressive stress (negative value) remaining at the end ( A) is large. Since the tensile stress and the compressive stress are balanced before the half-etching, no warpage occurs. However, when the dimple 12 is formed by half-etching one surface as shown in FIG. As shown in FIG. 10, a large warp occurs with the half-etched surface inside.

In the case of a conventional lead frame plate,
When the half-etching is performed, the warpage H occurs in the case of a lead frame having a length of 150 to 250 mm as shown in FIG.
₁ is about 50 mm at the maximum. Further, one side as shown in FIG. 12 with respect to the island portion of 10mm square, warpage H ₂ is about 50 [mu] m. In general, in the case of a square island part having a side of 10 mm, it is said that the warpage H ₂ needs to be 15 μm or less. In a conventional strip material for electric / electronic parts, the thickness is 2/3 to 1/2 in the thickness direction.
When a dimple having a depth of is formed, this criterion cannot be satisfied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has excellent flatness and is hardly warped even by half-etching. The aim is to provide a method.

[0006]

According to the present invention, there is provided a plate member for a half-etched electric / electronic part having a half-etched surface. A plate material comprising a tape, a plate or a strip, wherein the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction is 12 kgf / mm ² or less. There is a feature.

According to the method of manufacturing a strip material for an electric / electronic component for half etching according to the present invention, a metal or alloy tape, plate or strip material is passed through a tension leveler and the height of the wavy strain is reduced. The steepness obtained by dividing by the pitch is 1.
A first tension leveler step of reducing the thickness to 0% or less, and passing the plate material after completion of the first tension leveler step through a tension leveler while maintaining a constant tension in a thickness direction in a cross section parallel to the rolling direction. The sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution of
gf / mm ² or less.

Another method of manufacturing a plate material for an electric / electronic component for half etching according to the present invention is a first tension leveler for passing a metal or alloy tape, plate or strip through a tension leveler. And a second tension leveler step of passing the plate material after completion of the first tension leveler step through a tension leveler at a tension of 1/3 or less of the tension in the first tension leveler step. It is characterized by.

[0009] The steepness is obtained by dividing the height of the wavy strain generated in the strip by the pitch of the waves. Specifically, as shown in FIG. 13, when the distance between the wave bottoms of the wavy distortion generated in the tape, plate, or strip material is L and the height is H, the steepness = ( H / L) × 100.

In the present application, the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction is defined as the absolute value of the maximum value of the compressive stress in the residual stress distribution in the thickness direction and the tensile value. The sum of the maximum value of the stress and the absolute value.
In the case of a rolled material, the residual stress remaining in the direction perpendicular to the rolling direction is smaller than the residual stress remaining in the rolling direction.
In the present invention, the sum of the absolute value of the compressive stress remaining in the rolling direction and the absolute value of the tensile stress is set to 12 kgf / mm ² or less.

Further, the first and second tension leveler steps may be performed continuously by, for example, two tension levelers, or may be performed individually (discontinuously).

[0012]

The present inventors have conducted various experimental studies to suppress the warpage after half-etching of a plate member for an electric / electronic component made of a tape, a plate or a member having a rectangular cross section. As a result, for example, in a lead frame, the warpage after half-etching of a square island part having a side of 10 mm is reduced by one.
In order to reduce the thickness to 5 μm or less, the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction of the lead frame is set to 12
It has been found that it is necessary to make the weight not more than kgf / mm ² .

Further, the inventors of the present invention set the tension applied to the sheet material to be low at the time of correcting the distortion by the tension leveler, and set the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction. Was found to be smaller. However, if the tension at the time of passing through the tension leveler is reduced, the distortion of the strip material cannot be corrected.

Therefore, in the first invention method of the present application, first, as a first tension leveler step, the plate material is passed through a tension leveler while applying a relatively large tension to reduce the steepness to 1.0% or less. By doing so, the flatness required for the lead frame is ensured. This first
After the completion of the tension leveler step, the plate material has good flatness, but has relatively large residual stress in the stress distribution in the thickness direction. In order to reduce the residual stress, as a second tension leveler step, the plate material is passed through the tension leveler while keeping the tension constant. As a result, the residual stress can be reduced, and for example, in a lead frame, the warpage of a 10-mm square island can be reduced to 15 μm or less.

[0015] In the second invention method of the present application,
First, in a first tension leveler step, the plate material is passed through a tension leveler while applying a relatively large tension to secure a desired flatness, and then, in a second tension leveler process, the first strip material is applied to the plate material. Through the tension leveler while applying a tension of 1/3 or less of the tension in the tension leveler step. Thereby, the stress remaining on the plate material can be sufficiently reduced, and the occurrence of warpage after half-etching can be suppressed.

In the first and second invention methods,
As the tension in the first tension leveler process increases, the steepness of the strip material decreases, but if the tension is too high, the residual stress of the material after the first tension leveler process increases, and the second tension leveler increases. In order to reduce the residual stress in the process, the tension in the second tension leveler process needs to be close to one third of the tension in the first tension leveler process, and it becomes difficult to sufficiently reduce the residual stress. For this reason, the tension in the first tension leveler step is 9 to 25 kgf / mm.
It is preferred to be about ² . Further, by setting the tension in the second tension leveler step to 3 to 8 kgf / mm ² , the residual stress can be reduced more reliably. Further, when a work roll having a small diameter (16 mm or less) is used as the work roll of the tension leveler, the residual stress can be further reduced.

Although the present invention is mainly directed to a Cu alloy used for a lead frame, the present invention can be applied to other metals or alloys.

[0018]

Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a tension leveler used in a method of manufacturing a strip material for an electric / electronic component according to an embodiment of the present invention. The tension leveler includes a plurality of work rolls 1 and first and second intermediate rolls 2 and 3.
As shown in FIG. 2, a large amount x ₁ bite roll of the roll 1 of the entry side is set so that the amount x _n bite roll as the subsequent roll 1 is decreased. First and second
The intermediate rolls 2 and 3 are provided in order to reinforce the strength of the first work roll against bending stress. Also,
Bridle sections 4 and 5 each composed of a plurality of rolls are provided on the entrance side and the exit side of the tension leveler. The tension of the material to be processed (rolled material 10) between the bridle portions 4 and 5 can be adjusted by a method such as adjusting the tension of each roll of the bridle portions 4 and 5.

On the other hand, the final rolled material 10 to be treated (for example, a rolled Cu alloy material) is wound around a roll 6. The rolled material 10 is unwound from the roll 6, is wound between the rolls constituting the entrance bridle section 4, passes between the work rolls 1 of the tension leveler, and further rolls constituting the exit bridle section 5. After being wound around, it is taken up by a take-up roll 7.

In this embodiment, first, as a first tension leveler step, the elongation of the rolled material 10 is kept constant (for example, 0.25% or 0.3%), and the rolled material 10 is tensioned by a tension leveler. Through. In this case, the tension fluctuates (vibrates), but the average tension is, for example, 15 kgf / m.
and m ^2.

FIG. 3 shows the tension (unit tension) applied to the sheet material on the horizontal axis and the steepness on the vertical axis, and shows three types of sheet materials (A material, B material and C
FIG. 4 is a graph showing the relationship between unit tension and steepness of the material (material). The material A is a plate having a tensile strength about 1.5 times that of the material B, and the material C is a plate having a tensile strength of about 0.5 times that of the material B. As shown in FIG. 3, when the tension applied to the strip is increased, the steepness of the strip is reduced. When used as a lead frame, the steepness is set to 1% or less. Although the preferable range of the tension is different depending on the tensile strength of the sheet material, if the tension is too large, it is difficult to sufficiently reduce the residual stress in the second tension leveler step. For this reason, the tension applied to the strip material (rolled material 10) in the first tension leveler process is 9 to 25.
It is preferable to be about kgf / mm ² .

Next, as a second tension leveler step, the tension applied to the rolled material 10 is set to be 1/3 or less of the tension in the first tension leveler step, and the bridle parts 4, 5 are adjusted so that the tension is constant. Adjusted rolled material 1
Pass 0 through the tension leveler. In this case, it is preferable that the tension is set to 0 only in consideration of reducing the residual stress. However, when the tension is set to 0, a lateral flow of the rolled material 10 occurs in the tension leveler. For this reason, it is necessary to apply a minimum tension that does not cause lateral flow. Specifically, the tension in the second tension leveler step is preferably set to 3 to 8.3 kgf / mm ² .

As described above, by reducing the tension in the second tension leveler step to 1/3 or less of the tension in the first tension leveler step, the rolled material 1
The sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction of 0 can be reduced.

FIG. 4 shows the relationship between the work roll diameter in the second tension leveler process on the horizontal axis and the sum of the absolute value of the compressive stress and the absolute value of the tensile stress on the vertical axis. FIG. However, the tension in the first tension leveler step was 15 kgf / mm ² , the diameter of the work roll was 16 mm, and the tension in the second tension leveler step was 4.5 kgf / mm ² .
In addition, the sum of the absolute value of the compressive stress and the absolute value of the tensile stress of the plate material subjected to only the first tension leveler process is about 2
It is 2 kgf / mm ² . From FIG. 4, the work roll diameter in the second tension leveler step is set to 16 m.
It can be seen that the sum of the absolute value of the compressive stress and the absolute value of the tensile stress can be set to 12 kgf / mm ² or less by setting the value to m or less.

FIG. 5 is a schematic diagram showing the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction of the sheet material having undergone the first and second tension leveler processes. As shown in FIG. 5, the strip material 11 manufactured by the method of the present embodiment has a small compressive stress and a low tensile stress. Therefore, as shown in FIG. However, the compressive force acting on the half-etched surface is small, and the warpage is small as shown in FIG. Accordingly, when half-etching is performed on a square island part having a side of 10 mm in the lead frame, warpage can be suppressed to 15 μm or less.

Hereinafter, a plate material for a lead frame was actually manufactured by the method of the embodiment of the present invention, half etching was applied to an island portion of a lead frame formed from the plate material, and the result of examining the warpage was shown by the conventional method. A description will be given in comparison with examples and comparative examples.

As a raw material, a Cu alloy (Cu-3.2 wt% Ni-0.7 wt% Si-1.25 wt% Sn-
A thin plate having a thickness of 0.127 mm was prepared. The thin plate was passed through a tension leveler twice for Examples 1 to 4 and Comparative Example, and only once for the conventional example, while applying the tension shown in Table 1 below. In this case, the work roll diameter in the second tension leveler process of Example 4 is 12 mm, and the work roll diameter in the other tension leveler processes is 16 mm. In Conventional Example 2, low-temperature annealing (380 ° C. × 2 hours) was performed after passing through a tension leveler.

From the thin plate subjected to the straightening as described above,
A lead frame having a square island with one side of 10 mm was formed, and one surface of the island was half-etched. Then, the distribution in the thickness direction of the residual stress remaining in the rolling direction (L) and the direction perpendicular to the rolling direction (width direction: C) is examined, and the sum of the absolute value of the compressive stress and the absolute value of the tensile stress is obtained. Was. That is, (L) is a residual stress in a cross section parallel to the rolling direction, and (C) is a residual stress in a cross section orthogonal to the rolling direction. The results are shown in the column of residual stress in Table 1. The warpage of the island was measured with a three-dimensional tool microscope. The results are also shown in Table 1.

[0029]

[Table 1]

As is clear from Table 1, the residual stress (the sum of the absolute value of the compressive stress and the absolute value of the tensile stress) of each of the comparative example and the conventional examples 1 and 2 is 14 kgf / mm ² or more. Warpage of island after half etching (L)
Are as large as 17 μm, 50 μm, and 25 μm, respectively, whereas in Examples of the present invention, the residual stress is 1
2 kgf / mm ² or less, and the warpage (L) of each of the island portions is as small as 12 μm or less. This allows
It is apparent that the present invention is extremely useful for producing a strip material for an electric / electronic component subjected to half etching. Further, according to the present invention, it can be seen that the residual stress and the warpage in the direction (C) perpendicular to the rolling direction can also be reduced.

In each of the above-mentioned Examples 1 to 4, the heat treatment step is not provided before and after the tension leveler step, but is performed before and / or after the tension leveler step.
Alternatively, a heat treatment step may be added later. In addition, it is needless to say that the plate material for electric / electronic parts according to the present invention is not limited to the above-mentioned copper alloy, and the present invention is applicable to not only copper and copper alloy but also aluminum and aluminum alloy, 42 alloy and the like. It can also be applied. Further, the first and second tension leveler steps may be performed continuously by, for example, two tension levelers, or after the first tension leveler step is performed by one tension leveler, the tension may be reduced. After the adjustment, the second tension leveler step may be performed by the tension leveler.

[0032]

As described above, the strip material for electrical and electronic parts for half-etching according to the present invention has an absolute value of the compressive stress and a tensile stress of the tensile stress in the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction. Since the sum of the absolute value and the sum is regulated to a predetermined value or less, the warpage after half etching is extremely small.

Further, in the method for manufacturing a strip material for an electronic / electronic component for half etching according to the present invention, the steepness of the strip material is set to 1% or less in the first tension leveler step, and the steepness of the plate material is reduced in the second tension leveler step. Since the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction of the strip material is equal to or less than a predetermined value, the flatness is excellent, Even when the half-etching is performed, it is possible to obtain a plate material for an electric / electronic component having extremely little warpage.

Further, in another method of manufacturing a plate material for an electric / electronic part for half etching according to the present invention, the plate material is passed through a tension leveler in first and second tension leveler steps, respectively. The first in the process
Since the sheet is passed through the tension leveler at a low tension of 1/3 or less of the tension in the tension leveling step, the flatness is excellent, the residual stress is small, and the warpage is extremely small even when subjected to half etching. Material can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a tension leveler used in a method of manufacturing a plate material for an electric / electronic component according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an arrangement of work rolls of a tension leveler.

FIG. 3 is a graph showing a relationship between a tension (unit tension) applied to a strip material and a steepness.

FIG. 4 is a graph showing a relationship between a diameter of a work roll and a residual stress in a second tension leveler step.

FIG. 5 is a view showing a residual stress distribution in a thickness direction in a cross section parallel to a rolling direction of a strip obtained through first and second tension leveler processes.

FIG. 6 is a schematic diagram showing a state in which half etching has been performed on the strip material.

FIG. 7 is a schematic view showing the warpage of the plate material.

FIG. 8 is a diagram showing a residual stress distribution in a thickness direction in a cross section parallel to a rolling direction of a conventional strip for electric and electronic parts.

FIG. 9 is a schematic view showing a state in which half etching has been performed on the plate material.

FIG. 10 is a schematic view showing the warpage of the plate material.

FIG. 11 is a schematic view showing warpage when half etching is applied to a lead frame formed of a conventional strip material for electric / electronic parts.

FIG. 12 is a schematic view showing warpage when half-etching is performed on an island portion of a lead frame formed of a conventional plate member for electric / electronic parts.

FIG. 13 is a schematic diagram showing steepness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Work roll 2, 3; Intermediate roll 4, 5; Bridle part 10; Rolled material 11; Strip material 12; Dimple

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Koji Maeda 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel Works, Ltd. 14-1, Minatomachi Kobe Steel, Ltd., Chofu Works (72) Inventor Wakamitsu Nakamura, 14-1, Chofu Minatomachi, Shimonoseki, Yamaguchi Prefecture, Kobe, Ltd., Chofu Works, Kobe Steel, Ltd. 14-1, Chofu Minatomachi, Shimonoseki City Kobe Steel, Ltd. Chofu Works (58) Field surveyed (Int. Cl. ⁶ , DB name) B21D 1/05

Claims (6)

(57) [Claims] 1. A strip material for a half-etching electric / electronic part having one surface half-etched, which is a metal or alloy tape, plate or strip, and has a cross section parallel to the rolling direction. Wherein the sum of the absolute value of the compressive stress and the absolute value of the tensile stress in the residual stress distribution in the thickness direction is 12 kgf / mm ² or less. 2. The plate material for a half-etching electric / electronic part according to claim 1, wherein the metal or alloy is a Cu alloy. 3. A steepness obtained by passing a metal or alloy tape, plate or strip made of a metal or alloy through a tension leveler and dividing the height of the wavy strain by the pitch of the wave to 1.0% or less. In the first tension leveler step, the sheet material after the first tension leveler step is passed through the tension leveler while maintaining a constant tension, and the residual stress distribution in the thickness direction in a cross section parallel to the rolling direction is obtained. The sum of the absolute value of the compressive stress and the absolute value of the tensile stress is calculated as 12 kgf / mm ²
A method for producing a plate member for a half-etching electric / electronic component, comprising: a second tension leveler step described below. 4. A first tension leveler step of passing a metal or alloy tape, plate or strip plate material through a tension leveler, and the plate material after completion of the first tension leveler step is subjected to the first tension leveler process. A second tension leveler step of passing the tension through a tension leveler at a tension of 1/3 or less of the tension in the tension leveler step of (1). 5. The method according to claim 3, wherein the work roll diameter of the tension leveler in the second tension leveler step is 16 mm or less. . 6. The method according to claim 3, wherein the metal or alloy is a Cu alloy.