JPH06226369A - Die for cutting lead of electric part and others - Google Patents

Abstract

PURPOSE:To protect a comb teeth-shaped blade of a die in order to cut an IC lead. CONSTITUTION:A supporting plate 24 is attached on a die by inserting with pressing a die blade 23 in a recessing part 25. Therefore, one end of the die blade 23 is supported with the die 21 itself, and the other end is supported with the supporting plate 24. That is, in the die blade 23, both ends are supported and each die blade 23 is rigidly supported, therefore if the die blade 23 receives a one-sided load from a lateral side, the buckling or the breaking is not generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead cutting die for electric parts and the like. More specifically, the present invention relates to a mold structure for cutting a connecting portion between leads of an IC or an LSI having a very small lead pitch.

[0002]

BACKGROUND ART The shape of an LSI package is a conventional DIP.
A method of electrically connecting a component with a lead wire or a device package to a conductor on the surface of a printed wiring board without using a mounting hole for the lead wire from the center of the (dual incline package), a so-called so-called It is moving to surface mounting. This shift is to cope with an increase in the number of gates due to high-density, multi-function, and high speed of LSI chips. As one of surface mounting methods, a flat package type having leads on four sides is known and used. The processing of this IC lead usually includes the following lead cutting (separation) step.

As shown in FIG. 1, an LSI package 2 is mounted on a lead frame 1 in a previous step. This L
The SI package 2 is formed by bonding an IC chip (not shown) and the lead frame 1 with a gold wire or the like, and then packaging with a synthetic resin or the like. A large number of leads 3, 3 ... Are formed between the punched portions on the lead frame 1 around the LSI package 2 by punching (see a partially enlarged view of FIG. 2). The adjacent leads 3 and 3 are connected without being completely punched, and the connecting portions 3a, 3a ... Are removed by cutting along the chain line, and the LSI becomes operable only for the first time.

Conventionally, the cutting of the lead 3 has been performed by a mold shown in FIGS. FIG. 8 is a bottom view of the punch plate 10, and the punch 4 includes the connecting portions 3a, 3a ...
Corresponding to the overall shape of, the four sheets are arranged so as to have a substantially rectangular shape as a whole. At the tip of each punch 4, that is, at the lower end of the punch plate 10 in the moving direction, a large number of comb blade-shaped punch blades 5 extending in the vertical direction are provided at a pitch corresponding to the pitch of the leads 3.

On the other hand, the die 51 is provided with a rectangular die hole 52 in the upper portion, as shown in the plan view and the sectional view of FIGS. A large number of comb blade-shaped die blades 53 extending in a direction orthogonal to the blades 5 of the punch 4 are provided on the inner peripheral wall of the die hole 52. At the time of cutting the lead 3, the LSI package 2 is received in the die hole 52, and positioning is performed by inserting the positioning holes 6 at both ends of the lead frame 1 into pins (not shown) provided on the upper surface of the die 51. Then, the punch 4 descends, the punch blade 5 enters between the die blades 53, and the connecting portion 3a between the leads 3 is removed by the shearing action.

Conventionally, this mold is manufactured by grinding. However, the integration of semiconductors has advanced in recent years, and IC
The lead pitch is 0.5mm, which is getting smaller and smaller. Along with this, high precision is required for lead processing. Lead pitch of 0.32 in the near future
mm IC is expected to be produced. In this case, the punch and die blades also had an extremely thin comb shape like the hair of a human having a width of 0.14 mm, and the grinding process had a problem with the grindstone and could not be dealt with.

For this reason, application of wire electric discharge machining has been examined in place of grinding for die machining. But,
In ordinary wire electric discharge machining, an altered layer of about 0.02 mm was generated inside the electric discharge machined surface of the blade, and the blade broke early and could not be applied to actual machining. This is because from the thickness of about 0.02 mm to the cemented carbide material, the cobalt that acts as a glue elutes and becomes an altered layer that consists only of tungsten carbide, and the tungsten carbide that plays an important role as a blade of the mold easily falls off. It is considered to be the situation.

Therefore, when the present inventor machined using a wire electric discharge machine employing a special AC bias power source, no generation of an altered layer was observed. However,
As a result of the extremely small lead pitch, the blade becomes too thin,
The number of shots was unstable from 100 shots to 10,000 shots, and the die blade was broken or buckled and damaged, and the punch blade was also broken at the same time, and the die was not able to withstand full-scale production. That is, since the die blade is cantilevered and has a thin comb-like shape like hair, it can be bent by an unbalanced load from the side. In the punch, the thin comb-shaped stripper that supports the punch breaks due to an unbalanced load from the side like a die, and at the same time, the punch is broken and the punch blade also breaks.

[0009]

The present invention has been made based on the above technical background, and achieves the following objects.

An object of the present invention is to provide a die for cutting a lead of an electric component or the like, which protects a comb-shaped blade of a die or a punch and can prevent buckling or breakage.

Another object of the present invention is to provide a die for cutting a lead of an electric part or the like in which protection of a die and a punch is surely performed.

[0012]

The present invention adopts the following means in order to achieve the above object.

According to the present invention, a lead frame (1) is formed in which a large number of leads (3) are formed in parallel at a predetermined pitch, and a part of the leads (3, 3) adjacent to each other are connected. A die for cutting a lead for cutting a connecting portion (3a) between the leads, wherein a plurality of punch blades (5) are provided in parallel at the tip at a pitch corresponding to the pitch of the leads (3). A plurality of die blades (2) for cutting the connecting portion (3a) in cooperation with the punch blade (5) on the punch (4) and the peripheral wall of the die hole (22).
A die (21) provided with 3) arranged in parallel at a pitch corresponding to the pitch of the leads (3) and a large number of recesses (25) into which the tips of the die blades (23) are inserted are formed on the side surface. A die for cutting a lead of an electric component or the like, which is provided with a support plate (24) rigidly connecting the respective die blades (23).

Engaging portions (23a, 25) that engage with each other at the tip portion of the die blade (23) and the recess (25) in order to increase the rigidity of the die blade (23).
a) has been formed.

A stripper (17) having a large number of holes (31) for pressing the lead frame (1) against the die (21) and movably inserting and supporting the punch blade (25). ) And.

[0016]

The supporting plate is mounted on the die by inserting the tip of the die into the concave portion while pressing it into contact with the concave portion. As a result, one end of the die blade is supported by the die itself, and the other end is supported by the support plate. That is, both ends of the die blade are supported, and the die blades are rigidly connected. Therefore, even if the die blade receives an unbalanced load from the side, it does not buckle or break.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view showing the overall structure of the mold. The entire structure itself is the same as the conventional one, and will be briefly described. The mold comprises an upper mold 7 and a lower mold 8, and the upper mold 7 has a punch holder 9. On the upper surface of the punch holder 9, a shank 1 connected to a ram of a press machine (not shown)
0 is provided. The lower die 8 has a die holder 11. The die holder 11 is provided with a plurality of guide posts (not shown), and the punch holder 9 is guided by the guide posts to move up and down. The stopper 12 is for limiting the lowered position of the punch holder 9.

A punch plate 10 is provided on the lower surface of the punch holder 9. A hanging bolt 15 is movably inserted into a circular hole 14 provided in the punch plate 10, and the stripper plate 1 is attached to a lower end of the hanging bolt 15.
6 is fixed. A spring insertion hole 17 is formed in the punch holder 9 above the hanging bolt 15.

An adjusting bolt 18 is screwed into the upper end of the spring insertion hole 17. A coil spring 19 is interposed between the adjusting bolt 18 and the suspension bolt 15, and the spring force of the coil spring 19 is equal to that of the adjusting bolt 1.
Adjusted by 8.

A stripper 17 is held by a holder 18 on the lower surface of the stripper plate 16. Four punches 4 having comb-like punch blades 5 similar to those shown in FIGS. 8 and 9 are fixed to the punch plate 10. The punch 4 is movably inserted into the stripper plate 16 and the stripper 17, and protrudes from the lower surface of the stripper 17 when cutting the work. That is, when the punch holder 9 descends, both the punch plate 10 and the stripper 17 descend, and the stripper 17 first holds the work. Then, only the punch plate 12 moves downward by the stroke S against the coil spring 19, and the punch 4 projects from the lower surface of the stripper 17.

A die plate 20 is provided on the upper surface of the die holder 11. A die 21 is held on the die plate 20. 4 is a plan view of the die 21,
FIG. 6 is a vertical cross-sectional view, and FIG. 7 is an enlarged view showing a part of the horizontal cross-section.

The die 21 has a rectangular die hole 22 as a whole.
Are formed. The depth of the die hole 22 is about 6.0 mm in this embodiment. On the inner wall of the die hole 22,
As in the conventional case, a large number of comb blade-shaped die blades 23 extending in the direction orthogonal to the punch blades are provided at a pitch equal to the pitch of the leads 3. In this embodiment, the die blade 23 has a wall thickness of about 0.14 mm and is processed by wire electric discharge machining. The die blade 23 is cantilevered in a state where only wire electric discharge machining is performed. The support plate 24 rigidly connects the plurality of die blades 23.

The support plate 24 has a rectangular shape as a whole and is mounted in the die hole 22. Support plate 24
A large number of concave portions 25 are formed at equal intervals on the outer peripheral surface of the. The support plate 24 is made of cemented carbide, and the die blade 2
Similarly to 4, the protrusion 25 is also processed by wire electric discharge machining. The support plate 24 has a die blade 23 in each recess 25.
When the tip of the die is pressed and inserted, the die hole 2
It is installed in 2. By mounting the support plate 24, a closed gap 26 is formed between the die blades 23 adjacent to each other, only the upper portion of which is open and the four circumferences are closed.

As shown in the enlarged view of FIG. 6, a neck portion 23a is provided at the tip of each die blade 23. On the other hand, at the tip of each recess 25, a narrow space 25a with a narrow space
Is provided. By pressing the die blade 23 into each recess 25, the neck portion 23a and the narrow portion 25a of the die blade 23 are pressed.
Are engaged with each other, and the support plate 24 and the die blade 23
Of the die blade 23 is prevented, and the rigidity of the die blade 23 is further enhanced.

The LSI package 2 is received in the die hole 22 when cutting the leads. Therefore, the housing portion 27 of the LSI package 2 is formed above the support plate 24 by lowering the upper surface of the support plate 24 below the upper surface of the die 21. That is, the LSI package 2 is placed on the upper surface of the support plate 24.
In order to make the shape of the accommodating portion 27 conform to the shape of the LSI package 2, the inclined surface 2 is formed on the die blade 23 and the die.
8 and 32 are formed respectively.

FIG. 7 is an enlarged sectional view showing a part of the stripper. Stripper 17 is stripper body 1
7a and a support plate 30. The stripper body 17a is provided with a slit 29 into which the punch 4 is movably inserted. A support plate 3 for supporting the punch blade 5 is provided on the lower surface of the stripper body 17a.
0 is fixed. The support plate 30 is provided with a large number of small holes 31 into which the punch blades 5 are movably inserted. When the punch blade 5 is inserted into the small hole 31, the punch blade 5 is supported by the support plate 30 and lateral displacement is suppressed.

Cutting Method The lead frame 1 shown in FIG. 1 is a strip-shaped one, and although not shown, a plurality of LSI packages 2 are mounted at regular intervals in the longitudinal direction, and leads 3 are provided around each LSI package 2. Are formed. The lead frame 1 is carried by a carrying device or the like (not shown), and the LSI package 2 is set in the housing portion 27 of the die 21. Moreover, the positioning is performed by the positioning hole 6. In this state, the connecting portion 3a between the leads 3 is located on the closed gap 26 between the die blades 23.

When the punch holder 9 descends due to the operation of the ram, both the stripper 17 and the punch plate 15 descend, and the support plate 30 of the stripper 17 presses the lead frame 1 against the die 21. Only the punch plate 10 then descends against the coil spring 19, and the punch blade 5 moves to the support plate 3
It projects from the lower surface of 0. The punch blades 5 enter the closed gap 26 between the die blades 23 and are sheared to lead 3
The connecting portion 3 between them is cut off. At the time of cutting, even if an unbalanced load acts on the die blades 23, the die blades 23 are rigidly connected by the support plate 24, so that they do not buckle or break.

[0030]

As described above in detail, according to the present invention, buckling and breakage of the die blade can be reliably prevented, so that the lead pitch can be shortened sufficiently.

[Brief description of drawings]

FIG. 1 is a plan view showing a lead frame.

FIG. 2 is an enlarged plan view showing a lead.

FIG. 3 is a cross-sectional view of a mold.

FIG. 4 is a plan view showing the vicinity of a die hole of a die.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is an enlarged sectional view showing an engagement state between a die blade and a protrusion.

FIG. 7 is a cross-sectional view showing a lower portion of the stripper.

FIG. 8 is a bottom view of the punch plate.

FIG. 9 is a front view showing a punch.

FIG. 10 is a plan view showing a conventional die.

11 is a cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

 1 ... Lead frame 2 ... LSI package 3 ... Lead 3a ... Connection part 4 ... Punch 5 ... Punch blade 17 ... Stripper 21 ... Die 22 ... Die hole 23 ... Die blade 23a ... Neck 24 ... Support plate 25 ... Recess 25a ... Narrow part

Claims (3)

[Claims] 1. A plurality of leads (3) are formed in parallel at a predetermined pitch and are adjacent to each other.
3) A lead cutting die for cutting a connecting portion (3a) between the leads of a lead frame (1) in which a part of the lead (3) is connected to a tip of the lead (3) pitch. Punch (4) with a large number of punch blades (5) arranged in parallel at a corresponding pitch
And, on the peripheral wall of the die hole (22), a large number of die blades (23) for cutting the connecting portion (3a) in cooperation with the punch blade (5) correspond to the pitch of the leads (3). The dies (21) provided in parallel at the above pitch, and a large number of recesses (25) into which the tips of the respective die blades (23) are inserted are provided on the side surface, and the respective die blades (23)
And a support plate (24) for rigidly connecting the above. 2. The tip of the die blade (23) and the recess (25) according to claim 1.
Engagement portions (23a, 25a) that engage with and support each other in order to increase the rigidity of the die blade (23).
A die for cutting a lead of an electric component, etc. 3. A plurality of holes (31) according to claim 1, wherein said lead frame (1) is pressed against said die (21) and said punch blade (25) is movably inserted and supported. And a stripper (17) in which a lead is formed.