JPH098195A - Method and apparatus for down setting lead frame - Google Patents

Abstract

PURPOSE: To reduce the irregularity of the molding amount in the case of down setting by reducing the variation of the lower dead point of a punch even if a pressing pressure is changed with a simple structure. CONSTITUTION: The apparatus for down setting a lead frame comprises a lower die 10 mounted with a die 7, an upper die 1 for mounting a punch 2 at the lower part to move down it to the die 7 to down set it in a predetermined shape, two stoppers 4 fixed to both sides of the die 7 of the lower die 10 to decide the lower dead point of the punch 2 mounted at the lower part of the upper die 1 in collision with the moving-down upper die 1, and a plate 9 formed in section of substantially U shape and so disposed that the opening 9b is directed downward in the pressing pressure direction to be deformed by the pressure to alleviate the deformation of the upper die. Particularly, the opening size (x) of the plate 9 of the substantially U shape is preferably set to the same degree as the interval (y) of the two stoppers 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame downset processing method and apparatus.

[0002]

2. Description of the Related Art In general, downset processing is performed on a predetermined portion of a lead frame on which a semiconductor chip is mounted. For example, in COL (Chip On Lead), the tip portion of the inner lead on which the chip is mounted is bent so that it is one step lower than the bonding portion, and the height of the chip surface approaches the height of the bonding portion to facilitate wire bonding. There is.

FIG. 3 shows the structure of a general press die for performing downset processing on a lead frame. In order to perform the down setting, the upper die 1 guided by the guide post 8 descends, and the stripper 5
The lead frame 6 is fixed by. When the upper die 1 is further lowered from that state, the lead frame 6 is punched by the punch 2
And, the down-set processing is performed into a shape along the tool of the die 7. Here, the bottom dead center of the upper die 1 is two stoppers 4
Depends on

[0004]

By the way, in the above-mentioned conventional press die, since the bottom dead center position is determined by the two stoppers 4, as shown in FIG. When the pressing pressure P acts on the center of 4, the upper die 1 is bent. Therefore, the press pressure P
If the change occurs, the amount of bending of the upper die 1 changes according to the change, and the bottom dead center position of the punch 2 also changes by δ.

However, if the bottom dead center of the punch 2 changes,
Since the forming amount of the lead frame 6 changes, the downset shape and size also change, and the variation becomes large. For this reason, there is a drawback that it cannot be applied to downset processing with severe dimensional accuracy.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a lead frame downset processing method capable of achieving high accuracy by reducing the variation of the forming processing amount in downset processing. is there. Another object of the present invention is to provide a lead frame down-set processing apparatus that has a simple structure and can reduce fluctuations in the punch bottom dead center position even when the press pressure fluctuates.

[0007]

According to the method of the present invention, a press having a structure in which an upper die to which a pressing pressure is applied is abutted against a stopper fixed to a lower die to determine a bottom dead center of a punch attached to the upper die. The press pressure applied to the upper die is dispersed so as to alleviate the deformation of the upper die when the lead frame is downset by the die.

The device of the present invention comprises a lower die having a die attached thereto,
An upper die that attaches a punch and descends to perform downset processing of a predetermined shape on the lead frame with the die and an upper die that is fixed on both sides of the die attached to the lower die and collides with the descending upper die Determine the bottom dead center of the punch attached to the bottom of the 2
A book stopper, and a plate having a substantially U-shaped cross section, placed on the upper mold with its opening facing downward in the pressing direction, and deformed by press pressure to alleviate the deformation of the upper mold. It is a thing.

In this case, it is preferable that the size of the opening of the plate having a substantially U-shaped cross section is set to be approximately the same as the distance between the two stoppers.

[0010]

[Operation] The upper die is deformed when the pressing pressure is applied to the place separated from the stopper. When the press pressure fluctuates, the amount of deformation of the upper die changes according to the pressure, which causes the bottom dead center position of the punch to fluctuate.

However, when the press pressure applied to the upper mold is reduced so as to alleviate the deformation of the upper mold during downset processing as in the method of the present invention, the deformation of the upper mold is suppressed, so that the pressing pressure fluctuates. However, the position of the bottom dead center of the punch attached to the upper die does not change, so that the downset shape and dimensions do not change and the variation becomes small.

Further, like the apparatus of the present invention, a plate having a substantially U-shaped cross section is arranged on the upper mold so as to face downward in the pressing direction, and pressing pressure is applied to the upper mold through the plate. In this case, since the opening portion of the thin plate is deformed according to the pressing pressure, even if the pressing pressure fluctuates, the upper die is not deformed so much that the fluctuation of the punch bottom dead center position can be reduced.

Further, when the opening size of the plate is set to be approximately the same as the distance between the two stoppers, most of the pressing pressure applied to the upper die is received by the stoppers, so that the pressing pressure fluctuates. However, the upper die is hardly deformed, and the fluctuation of the punch bottom dead center position can be further reduced.

[0014]

Embodiments of the present invention will be described below. FIG.
The schematic block diagram of the down set processing apparatus of the lead frame by a present Example is shown.

This apparatus comprises a lower die 10 having a die 7 attached thereto.
The punch 2 is attached to the lower part, and the punch 2 is fixed along both sides of the die 7 of the lower die 10 and the upper die 1 that descends along the guide posts 8 to perform downset processing of a predetermined shape with the die 7.
Two stoppers 4 that determine the bottom dead center of the punch 2 attached to the lower part of the upper mold 1 in abutment with the descending upper mold 1 are provided. Up to this point, the structure is the same as the conventional structure.

The different point is that a plate 9 is provided on the upper die 1 to reduce the deformation of the upper die 1. This plate 9 has a substantially U-shaped cross section, and its opening 9
b is arranged on the upper part of the upper mold 1 so as to face downward in the pressing direction, and the opening pressure of the thin wall is deformed by the pressing pressure so that the deformation of the upper mold is alleviated. The opening dimension x of the plate 9 having a substantially U-shaped cross section is set to be approximately the same as the interval y of the two stoppers 4, and most of the press pressure applied to the upper die 1 via both leg portions 9a of the plate 9 is 2. It is adapted to be added on the stopper 4 of the book.

Reference numeral 5 is a stripper for fixing the lead frame 6 with the die 7, and is biased in the pressing direction by a spring 3 provided in the punch holder 11.

Now, in the above-mentioned structure, a pressing pressure is applied to the center of the plate 9 to lower the upper mold 1 and fix the periphery of the lead frame 6 between the stripper 5 and the die 7 first. From this state, the upper die 1 further descends, but the lower die 1 collides with the stopper 4 and stops the descending. After that, the press pressure P increases until the load becomes constant, and the down-set processing of the lead frame 6 is completed. Here, in the case where the plate 9 is not provided, if the pressing pressure P changes, the bending amount of the upper die 1 also changes.

However, since the plate 9 having a U-shaped cross section is provided so that both legs 9a correspond to the positions of the two stoppers 4, as shown in FIG. When the plate 9 itself bends and the press pressure P fluctuates, part of the fluctuation is absorbed by the plate 9. Therefore, the curvature of the upper die 1 is alleviated, the upper die 1 can be kept flat, and the bottom dead center fluctuation of the punch 2 is reduced.

Here, the remaining load variation is the stopper 4
However, since the stopper 4 has sufficiently high rigidity with respect to the load P, the compression deformation is so small that it can be ignored. Therefore, the deformation of the bottom dead center of the punch 2 due to the compressive deformation of the stopper 4 is not affected.

As described above, according to this embodiment, a plate having a substantially U-shaped cross section is arranged on the upper die of the press die so as to be opened downward in the pressing direction, and the plate is deformed during down setting. As a result, deformation of the upper mold is suppressed, so that it is possible to significantly reduce dimensional variations due to the dow set processing.

[0022]

According to the method of the present invention, since the pressing pressure applied to the upper mold so as to alleviate the deformation is dispersed in the upper mold that abuts against the stopper and tries to deform, the pressing pressure fluctuates. Also, the variation of the punch bottom dead center position during downset processing becomes extremely small, and a highly accurate lead frame with downset can be obtained.

According to the apparatus of the present invention, with a simple structure in which a plate having a substantially U-shaped cross section is provided on the upper die, even if the press pressure fluctuates, the fluctuation of the punch bottom dead center position can be reduced. .

When the size of the opening of the plate is set to be approximately the same as the distance between the two stoppers, the variation of the punch bottom dead center position can be further reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a lead frame down-set processing apparatus of the present invention.

FIG. 2 is an explanatory view showing a modification of the upper mold and the plate at the time of down setting of the present embodiment.

FIG. 3 is a cross-sectional view of a conventional lead frame downset processing apparatus.

FIG. 4 is an explanatory view showing the bending of the upper mold during down setting of the conventional example.

[Explanation of symbols]

 1 Upper mold 2 Punch 4 Stopper 6 Lead frame 7 Die 9 Plate 9b Opening 10 Lower mold P Press pressure

 ─────────────────────────────────────────────────── --- Continuation of front page (72) Inventor Ryuji Yonemoto 3550 Kidayo-cho, Tsuchiura-shi, Ibaraki Hitachi Cable Co., Ltd. System Materials Laboratory (72) Inventor Toshikatsu Hiroe 3-1-1 Sukegawa-cho, Hitachi-shi, Ibaraki No. Hitachi Cable Co., Ltd. inside the cable factory

Claims (3)

[Claims] 1. A lead mold is downset processed by a press die having a structure in which an upper die to which a pressing pressure is applied is made to abut a stopper fixed to the lower die to determine a bottom dead center of a punch attached to the upper die. A lead frame down-set processing method in which the pressing pressure applied to the upper mold is dispersed so as to alleviate the deformation of the upper mold. 2. A lower die having a die attached thereto, an upper die having a punch attached and descending to perform downset processing of a predetermined shape on the lead frame, and fixed to both sides of the die attached to the lower die. And two stoppers that abut the descending upper die to determine the bottom dead center of the punch attached to the lower part of the upper die, and have a substantially U-shaped cross section so that the opening faces downward in the pressing direction. A down set processing device for a lead frame, which includes a plate placed on an upper die and deformed by a press pressure to reduce deformation of the upper die. 3. The lead frame downset processing apparatus according to claim 2, wherein the size of the opening of the plate having a substantially U-shaped cross section is set to be approximately the same as the distance between the two stoppers.