JP3637666B2 - Lead frame material with excellent punchability - Google Patents
Lead frame material with excellent punchability Download PDFInfo
- Publication number
- JP3637666B2 JP3637666B2 JP02493496A JP2493496A JP3637666B2 JP 3637666 B2 JP3637666 B2 JP 3637666B2 JP 02493496 A JP02493496 A JP 02493496A JP 2493496 A JP2493496 A JP 2493496A JP 3637666 B2 JP3637666 B2 JP 3637666B2
- Authority
- JP
- Japan
- Prior art keywords
- lead frame
- frame material
- hardness
- comparative example
- rolling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Metal Rolling (AREA)
- Lead Frames For Integrated Circuits (AREA)
Description
【0001】
【発明の属する技術分野】
本発明は、ピン間隔の狭い多ピンリードフレーム用材料に関する。
【0002】
【従来の技術】
電子精密機器の小型化、多機能化を実現するためにICパッケージの高密度実装、高集積化が要求される。これに伴って、シリコンチップの多ピン化が進み、これに用いられるリードフレームのピンピッチも0.16mm以下と非常に小さくなっている。このようにピンピッチの小さいリードフレームにおいては、リードフレームの打抜きの際に発生するバリのために回路が短絡する恐れがあるため、打抜き加工時のバリ発生が小さいリードフレーム材が必要とされている。
【0003】
一般に、打抜き加工時のバリ発生を低減するためには材料の延性を下げることが有効であるとされている。リードフレーム材の延性を低減するには、例えば、その冷間加工率を高めて硬さを高めればよい。ところで、リードフレームの場合、その製造時においてリードフレーム材に曲げ加工を加える必要があるため、リードフレーム材は、この曲げ加工に耐えるだけの延性を維持することが要求される。そして、ここに要求される延性としては、一般的には、引張試験における破断伸びの値として8%以上とされている。
【0004】
しかし、リードフレームの打抜き加工時のバリを低減するのに、冷間加工の加工率を高めることによって行おうとすれば、リードフレーム材として所要の延性を維持することが困難になる。
【0005】
【発明が解決しようとする課題】
本発明は、上記の現状に鑑みて行われたもので、その目的とするところは、リードフレーム材として所要の延性を維持しつつ、しかも、リードフレームの打抜き加工時に発生するバリを低減し得る打ち抜き加工用リードフレーム材を提供することにある。
【0006】
【課題を解決するための手段】
上記目的を達成するために、本発明の打抜き性に優れた打ち抜き加工用リードフレーム材は、冷間圧延によって製造するNi−Fe合金系リードフレーム材において、最終仕上圧延前に前記リードフレーム材の表面にヘアライン加工を行い、その後最終仕上圧延を行うことによって、前記リードフレーム材の表面に硬化層を形成したことを特徴とする。
【0007】
【発明の実施の形態】
本発明の打抜き性に優れたリードフレーム材は、Ni−Fe合金、銅合金などリードフレーム材としての有用性を有する合金をもとに製造される。溶解、熱間圧延、冷間圧延、焼鈍等の工程はリードフレーム材に対する一般的な方法が適用できる。リードフレーム材として所要の寸法、および機械的性質を付与するために、前記合金に対して、適宜繰返して、焼鈍と冷間圧延とを施す。そして、前記製造工程の最終の仕上圧延を行う直前の材料(仕上圧延直前材と称する)、或いは最終の仕上圧延を行った材料(仕上圧延材と称する)に対してヘアライン加工を施す。仕上圧延としては冷間圧延を行う。
【0008】
ヘアライン加工は、被加工材(仕上圧延直前材または仕上圧延材)の表面に摩擦材を押し当てて摩擦する方法によって行う。これによって、前記仕上圧延直前材または仕上圧材の表層部に適度の加工硬化層を形成する。加工硬化層の形成が過大となるとリードフレームとして所要の延性が失われ、また、加工硬化層の形成が不十分であれば、リードフレーム打抜き時においてバリの生成を低減する効果が失われる。該ヘアライン加工における適度な加工の程度は、素材の種類、冷間圧延において素材に加える加工度等によって異なるので一概には決められない。ヘアライン加工における加工の程度は、前記仕上圧延直前材または仕上圧延材の表層部に適度な加工硬化層を形成する量であることを要する。
【0009】
仕上圧延直前材についてはヘアライン加工の後、最終仕上圧延を施してリードフレーム材として所要の寸法、および機械的性質を付与する。
【0010】
【実施例】
以下、本発明の実施例について説明する。
(実験1)
溶解−鍛造−熱間圧延−冷間圧延−焼鈍によって、厚さ0.2mm×幅40mmのFe−42質量%Ni合金の板を作成した(この板を材料Aと称する)。材料Aを、冷間圧延により厚さ0.15mmの板に圧延した(この板を材料Bと称する)。次に、摩擦材として#1000のブラシを用い、材料Bの表面を摩擦してヘアライン加工を行ってヘアライン加工材(実施例1)を得た。
(実験2)
摩擦材として#1000のブラシを用い、前記材料Aの表面にヘアライン加工を施した(該ヘアライン加工材を材料Cと称する)。次に、材料Cを冷間圧延によって板厚0.15mmに加工して冷間圧延材(実施例2)を得た。
【0011】
実施例1の供試材について、深さ方向の硬さ分布を調べるため、測定荷重を変えて表面のビッカース硬さを測定した。比較のために材料A(比較例1)および材料B(比較例2)についても同様に表面のビッカース硬さを測定した。その結果、図1に示すように比較例1および比較例2においては測定荷重が変っても硬さ測定値には差がないが、実施例1においては測定荷重の増加に伴って硬さ測定値は減少した。このことは実施例1の硬さが表層では高く、内部に向かって硬さが低下していくことを示している。
【0012】
実施例2および材料C(比較例3)の供試材についても測定荷重を変えて表面のビッカース硬さを測定した。その結果を図2に示す。図2において比較例3に見られるように、焼鈍材である材料Aにヘアライン加工を施すことにより表層部が硬化する。さらにこれを冷間圧延することによって、実施例2に示されるように全体の硬さが上昇するが、実施例2においても表層部は内部に比べて高い硬さを維持している。
【0013】
各材料の表層硬さ、内部硬さおよびJIS13号B引張試験片による破断伸びの値を表1に示す。本発明の実施例はいずれも、内部硬さが同等な比較例2とほぼ同等な破断伸びを示している。しかも、本発明の実施例は表層硬さは比較例2より高い。
【0014】
【表1】
【0015】
冷間プレスによって、実施例1および実施例2の供試材から幅0.2mm×長さ5mmの小片を打抜き、打抜き孔の周辺に生じたバリの体積をレーザー顕微鏡を用いて測定した。比較のためにヘアライン加工を行っていない材料B(比較例2)についても同様にして発生したバリの体積を測定した。その結果を表1に併せて示す。表層部に硬化層を有する本発明の実施例はいずれも、比較例2と内部硬さは同等であるが、比較例2に比べてバリの発生量が1/3以下に減少していることが判る。
【0016】
なお、最終工程としてヘアライン加工を行った実施例1の表面粗さがRa=3.2μmであったのに対して、最終工程として冷間加工を行った実施例2では、表面粗さRa=1.1μmと、約1/3の値を示す。
以上のように、本発明の実施例は、リードフレーム材として満足すべき硬さと延性を有する比較例2に比べて、同等の内部硬さと、ほぼ同等な破断伸びを示している。しかも、本発明の実施例の表層硬さは比較例2より高く、打抜き時のバリの発生が著しく少ない。
【0017】
【発明の効果】
本発明によれば、リードフレーム材として所要の延性を維持しつつ、しかも、リードフレームの打抜き加工時に発生するバリを低減する、打抜き性に優れたリードフレーム材を提供することができる。
【図面の簡単な説明】
【図1】実施例1のビッカース硬さ試験における測定荷重と表面硬さ測定値との関係を示す特性図である。
【図2】実施例2のビッカース硬さ試験における測定荷重と表面硬さ測定値との関係を示す特性図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-pin lead frame material having a narrow pin interval.
[0002]
[Prior art]
In order to realize miniaturization and multi-functionalization of electronic precision equipment, high-density mounting and high integration of IC packages are required. Along with this, the number of pins of the silicon chip has increased, and the pin pitch of the lead frame used for this has become very small, 0.16 mm or less. In such a lead frame with a small pin pitch, there is a possibility that the circuit may be short-circuited due to burrs that are generated when the lead frame is punched, and therefore a lead frame material that generates less burrs during punching is required. .
[0003]
In general, it is considered effective to reduce the ductility of a material in order to reduce the occurrence of burrs during punching. In order to reduce the ductility of the lead frame material, for example, the cold working rate may be increased to increase the hardness. By the way, in the case of a lead frame, since it is necessary to bend the lead frame material at the time of manufacture, the lead frame material is required to maintain ductility enough to withstand this bending process. The ductility required here is generally 8% or more as the value of elongation at break in a tensile test.
[0004]
However, if an attempt is made to reduce the burrs during the lead frame punching process by increasing the cold working rate, it becomes difficult to maintain the required ductility as the lead frame material.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described situation, and an object of the present invention is to maintain the required ductility as a lead frame material and to reduce burrs generated during the lead frame punching process. The object is to provide a lead frame material for punching .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a punching lead frame material having excellent punchability according to the present invention is a Ni-Fe alloy-based lead frame material manufactured by cold rolling. A hard layer is formed on the surface of the lead frame material by performing hairline processing on the surface and then performing final finish rolling.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The lead frame material excellent in punchability of the present invention is manufactured based on an alloy having utility as a lead frame material such as a Ni-Fe alloy and a copper alloy. A general method for the lead frame material can be applied to processes such as melting, hot rolling, cold rolling, and annealing. In order to impart the required dimensions and mechanical properties as the lead frame material, annealing and cold rolling are repeatedly performed on the alloy as appropriate. Then, hairline processing is performed on the material immediately before the final finish rolling in the manufacturing process (referred to as a material immediately before finish rolling) or the material that has been subjected to the final finish rolling (referred to as a finish rolled material). As finish rolling, cold rolling is performed.
[0008]
Hairline processing is performed by a method in which a friction material is pressed against the surface of a workpiece (finished material just before finish rolling or finish rolled material) and rubbed. As a result, an appropriate work hardened layer is formed on the surface layer portion of the material immediately before finish rolling or the finish pressure material. If the work hardened layer is excessively formed, the required ductility of the lead frame is lost, and if the work hardened layer is not sufficiently formed, the effect of reducing the generation of burrs at the time of punching the lead frame is lost. The appropriate degree of processing in the hairline processing cannot be determined unconditionally because it varies depending on the type of material, the degree of processing applied to the material in cold rolling, and the like. The degree of processing in the hairline processing needs to be an amount that forms an appropriate work hardening layer on the surface layer portion of the material immediately before the finish rolling or the finish rolling material.
[0009]
The material immediately before the finish rolling is subjected to the final finish rolling after the hairline processing to give the required dimensions and mechanical properties as the lead frame material.
[0010]
【Example】
Examples of the present invention will be described below.
(Experiment 1)
An Fe-42 mass% Ni alloy plate having a thickness of 0.2 mm and a width of 40 mm was prepared by melting-forging-hot rolling-cold rolling-annealing (this plate is referred to as material A). Material A was rolled into a 0.15 mm thick plate by cold rolling (this plate is referred to as material B). Next, using a # 1000 brush as a friction material, the surface of the material B was rubbed to perform hairline processing to obtain a hairline processing material (Example 1).
(Experiment 2)
Using a # 1000 brush as a friction material, the surface of the material A was subjected to hairline processing (the hairline processing material is referred to as material C). Next, the material C was processed into a plate thickness of 0.15 mm by cold rolling to obtain a cold rolled material (Example 2).
[0011]
In order to investigate the hardness distribution in the depth direction of the test material of Example 1, the measurement load was changed and the surface Vickers hardness was measured. For comparison, the surface Vickers hardness of the material A (Comparative Example 1) and the material B (Comparative Example 2) was similarly measured. As a result, as shown in FIG. 1, in Comparative Example 1 and Comparative Example 2, there is no difference in the hardness measurement value even when the measurement load changes, but in Example 1, the hardness measurement is performed as the measurement load increases. The value decreased. This indicates that the hardness of Example 1 is high in the surface layer, and the hardness decreases toward the inside.
[0012]
For the test materials of Example 2 and Material C (Comparative Example 3), the Vickers hardness of the surface was measured by changing the measurement load. The result is shown in FIG. As seen in Comparative Example 3 in FIG. 2, the surface layer portion is cured by applying a hairline process to the material A that is an annealing material. Further, by cold rolling this, the overall hardness increases as shown in Example 2, but also in Example 2, the surface layer part maintains a higher hardness than the inside.
[0013]
Table 1 shows the surface hardness, internal hardness, and elongation at break according to JIS No. 13 B tensile test piece of each material. Each of the examples of the present invention shows almost the same breaking elongation as that of Comparative Example 2 having the same internal hardness. Moreover, the surface hardness of the examples of the present invention is higher than that of Comparative Example 2.
[0014]
[Table 1]
[0015]
A small piece having a width of 0.2 mm and a length of 5 mm was punched from the specimens of Example 1 and Example 2 by cold pressing, and the volume of burrs generated around the punched hole was measured using a laser microscope. For comparison, the volume of burrs generated in the same manner was measured for the material B (Comparative Example 2) that was not subjected to hairline processing. The results are also shown in Table 1. In all the examples of the present invention having a hardened layer in the surface layer portion, the internal hardness is equivalent to that of Comparative Example 2, but the amount of burrs generated is reduced to 1/3 or less compared to Comparative Example 2. I understand.
[0016]
In addition, while the surface roughness of Example 1 which performed hairline processing as the last process was Ra = 3.2 micrometers, in Example 2 which performed cold processing as the last process, surface roughness Ra = 1.1 μm, a value of about 1/3.
As described above, the example of the present invention shows the same internal hardness and almost the same elongation at break as compared with the comparative example 2 having the hardness and ductility that are satisfactory as a lead frame material. Moreover, the hardness of the surface layer of the examples of the present invention is higher than that of Comparative Example 2, and the occurrence of burrs at the time of punching is extremely small.
[0017]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the lead frame material excellent in the punchability which reduces the burr | flash which generate | occur | produces at the time of the punching process of a lead frame, maintaining a required ductility as a lead frame material can be provided.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing a relationship between a measured load and a surface hardness measurement value in a Vickers hardness test of Example 1. FIG.
2 is a characteristic diagram showing a relationship between a measured load and a surface hardness measurement value in a Vickers hardness test of Example 2. FIG.
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02493496A JP3637666B2 (en) | 1996-02-13 | 1996-02-13 | Lead frame material with excellent punchability |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02493496A JP3637666B2 (en) | 1996-02-13 | 1996-02-13 | Lead frame material with excellent punchability |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP2004343598A Division JP2005123639A (en) | 2004-11-29 | 2004-11-29 | Lead frame material having excellent punching propety |
Publications (2)
Publication Number | Publication Date |
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JPH09219483A JPH09219483A (en) | 1997-08-19 |
JP3637666B2 true JP3637666B2 (en) | 2005-04-13 |
Family
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Application Number | Title | Priority Date | Filing Date |
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JP02493496A Expired - Fee Related JP3637666B2 (en) | 1996-02-13 | 1996-02-13 | Lead frame material with excellent punchability |
Country Status (1)
Country | Link |
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JP (1) | JP3637666B2 (en) |
-
1996
- 1996-02-13 JP JP02493496A patent/JP3637666B2/en not_active Expired - Fee Related
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JPH09219483A (en) | 1997-08-19 |
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