JPH0737428U - Die for punching lead frame - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a die for die cutting of a lead frame capable of punching a lead frame having a high shape accuracy by making the surface pressure of the stripper plate uniform. [Structure] Before punching (at the top dead center of the press), only the preliminary pressure is applied to the stripper plate 7 from the spring 3, and the stripper plate is not deformed. It is in a convexly curved state. When the press 8 comes to the bottom (bottom dead center), the force of the spring 3 on the stripper plate 7 becomes maximum and the deformation of the stripper plate 7 becomes maximum. At this time, the pressing surface 6 is also deformed and curved convexly, but it becomes parallel to the material 5 to be punched, and the material 5 to be punched can be pressed with a uniform pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a die for punching a lead frame, and more particularly to improvement of a pressing surface of a stripper plate against a material to be punched.

[0002]

[Prior art]

 FIG. 4A shows a lead frame punching die (hereinafter referred to as a working die) which is conventionally used to sequentially feed a lead frame as a material to be punched and perform punching step by step. Due to its structure, the arrangement of members such as the spring 3 for generating the surface pressure on the stripper plate 1 that press-fixes the material to be punched 5 is limited, and the punch 2 arranged at the so-called center of the die is limited. There was a limit to how close they could be placed.

Therefore, the pressing force applied to the material to be punched 5 by the stripper plate 1 is relatively low on the pressing surface 6 centered on the punch, and the stripper plate 1 is accordingly As shown in FIG. 4 (B), the material to be punched 5 was curved and deformed into a concave shape, and the material to be punched 5 as a whole could not be pressed with a uniform pressure.

In order to solve this problem, a means of providing a minute protrusion on a part of the outer side of the pressing surface 6 close to the punch side of the stripper plate to effectively press the material to be punched has been studied. Only the indentation 14 due to the protrusion remains on the material to be punched, which is not preferable in appearance.

[0005]

[Problems to be solved by the device]

 As described above, when punching is performed in a state where the stripper plate is curved in a concave shape, the lead 9 is used for a material to be punched in FIG. 3 that requires a precise punching process such as an IC lead frame. Since there is a problem in that the cross-sectional shape of the punched portion 10 that is twisted is originally a quadrangle, it is deformed into a rhombus. There is a problem of moving (shifting). All of these are the major causes of defective products. For the same reason, the stripper plate surface pressure is applied non-uniformly to the lead frame, so that the outer side 12 of the lead frame is relatively strongly pressed, and thus the outer side of the lead frame is greatly stretched. There is a problem that the frame is deformed.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to make the surface pressure of the stripper plate uniform so that a lead frame having a high shape accuracy can be punched. It is to provide the mold.

[0007]

[Means for Solving the Problems]

 The gist of the present invention resides in that the pressing surface of the stripper plate facing the material to be punched is curved so as to bulge toward the material to be punched, thereby arranging members such as springs behind the stripper plate. Despite (as it is now), the strip plate's surface pressure is made uniform.

That is, the above object of the present invention is to provide a die for a lead frame punching process, which comprises a punch, a die, and a stripper plate for pressing and fixing the punched material in punching, and facing the punched material of the stripper plate. A lead frame punching die, characterized in that the pressing surface is a curved surface that swells toward the material to be punched as a whole.

The lead frame punching die set forth above, wherein a minute projection is provided on a part of the outer side of the pressing surface of the stripper plate which is close to the punch side. Achieved by

[0010]

FIG. 1 shows an embodiment of a die for punching a lead frame according to the present invention.

Before the punching process (at the top dead center of the press), only the preliminary pressure from the stripping 3 is applied to the stripper plate 7, and the stripper plate is not deformed. As shown in FIG. 3, the pressing surface 6 is in a state of being convexly curved with respect to the material to be punched 5. At the same time when the press 8 comes down, the force of the spring 3 acting on the stripper plate 7 increases, and when the press 8 comes to the bottom (bottom dead center), it moves to the stripper plate 7 as shown in FIG. 1 (B). The force of the spring 3 is maximized, and the deformation of the stripper plate 7 is also maximized. At this time, the pressing surface 6 is also deformed and convexly curved, but it becomes parallel to the material to be punched 5, and the material to be punched 5 can be pressed with a uniform pressure. As a result, during lead punching, lead deformation and lead frame warp deformation do not occur and it is possible to mass-produce punched lead frames with high shape accuracy.

As shown in FIG. 2, the effect can be further enhanced by using the stripper plate having the minute projections 13 on a part of the outer side of the pressing surface of the stripper plate 1 which is close to the punch side.

[0013]

[Effect of device]

 When the lead frame punching die of the present invention is used for punching the lead frame, the surface pressure of the stripper plate is improved, the lead shape accuracy is improved, and the warp deformation of the lead frame is reduced. It

Further, according to the present invention, when designing a machining die, it becomes easy to arrange a spring that supplies a pressing pressure to the stripper plate, and the lead frame is not deformed during punching. It is not necessary to attach a tool, and a compact and inexpensive processing die can be designed.

The effect can be further enhanced by providing a minute protrusion on a part of the outer side of the pressing surface of the stripper plate which is close to the punch side.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a die for punching a lead frame of the present invention, at a press top dead center (A) and a press bottom dead center (B).

FIG. 2 is a side view of an embodiment of a stripper plate used in a die for punching a lead frame of the present invention.

FIG. 3 is an explanatory view of an IC lead frame processed by a processing die in which a projection is provided on a part of a pressing surface of a conventional stripper plate.

FIG. 4 is a cross-sectional view of a mold using a conventional stripper plate, at the press top dead center (A) and at the press bottom dead center (B).

[Explanation of symbols]

 1 Stripper Plate (Conventional) 2 Punch 3 Spring 4 Presser Pressure Transmission Rod 5 Stamping Material 6 Pressing Surface 7 Stripper Plate (Invention) 8 Press 9 Lead 10 Punching Part 11 Inner Lead Tip 12 Outside of Lead Frame 13 Micro-protrusion 14 Traces of micro-protrusion

Claims (2)

[Scope of utility model registration request] 1. A lead frame die for punching, comprising a punch, a die, and a stripper plate for pressing and fixing the material to be punched at the time of punching, wherein the pressing surface of the stripper plate facing the material to be punched is entirely A lead frame punching die, which has a curved surface that bulges toward the material to be punched. 2. A die for punching a lead frame according to claim 1, wherein a minute projection is provided on a part of the outer side of the pressing surface of the stripper plate which is close to the punch side.