JP3419579B2 - Press die for lead frame - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for punching a lead frame used for manufacturing a lead frame by a punching process.

[0002]

2. Description of the Related Art Lead frame products manufactured by a press punching process sequentially press the lead frame materials according to a predetermined punching shape while sequentially feeding the lead frame materials, and finally obtain a product having a required lead pattern. . FIG. 7 exemplarily shows a state in which the lead frame material 5 is press-punched several times. In the figure, 6 indicates a blank portion that has already been punched by a punch, and 7 indicates a portion that is punched by the processing stage.

The punch 8 and the die 9 are manufactured with high precision in accordance with the punching shape at the working stage, and the lead frame material 5 transferred to the working stage is press-punched and then Transferred to the stage. FIG. 8 is a cross-sectional view showing how the lead frame material 5 is press-punched with the punch 8 and the die 9. A stripper bush 10 guides and supports the punch 8, and has a function of clamping and holding the lead frame material 5 with the die 9 when punching with the punch 8.

[0004]

FIG. 8A shows a state in which the lead frame material 5 is held by the stripper bush 10. In FIG. 7, the shaded portion A corresponds to the portion A in FIG. 8A and shows the range in which the stripper bush 10 holds the lead frame material 5. As described above, the stripper bush 10 presses the lead frame material 5 between itself and the die 9 so that the punch 8 can perform the punching with high accuracy. Due to the narrow width, the stripper bushing 10 does not hold the lead frame material 5 sufficiently, and as shown in FIG.
There is such a thing as a twist.

This is because even if the lead frame material 5 is pressed by the stripper bushing 10 as shown in FIG. 7, the pressing force of the stripper bushing 10 does not sufficiently act on an extremely narrow portion such as the tip portion of the inner lead. Caused by. The pressing by the stripper bush 10 becomes a problem when the lead width approaches the thickness of the lead frame material 5. When the lead frame material 5 is not pressed down sufficiently, the lead 5a is twisted and the bottom surface of the lead 5a becomes a ridge shape.

The lead 5 in the press punching process
A conventional method for preventing the twisting of a is a stripper bush 10 in which the pressing surface is simply a flat surface as shown in FIG. 4, and a protrusion 12 is provided on the pressing surface as shown in FIG. In this method, the pressing force of the stripper bush 10 is concentrated on the protrusion 12 to ensure the pressing of the lead frame material 5. FIG. 6 shows a state in which the stripper bush 10 is pressed by the protrusion 12.

However, the method of simply providing the protrusion 12 on the stripper bush 10 as shown in FIG. 5 is not sufficient to eliminate the twist and richness of the lead portion in the manufacture of a lead frame product having an extremely narrow lead. Met. As described above, the present invention provides a lead frame press-punching die that prevents twisting and richness that occur in the molding of narrow lead portions, which is a problem in press-punching molding, and enables more accurate press-punching. It is intended to be provided.

[0008]

The present invention has the following constitution in order to achieve the above object. That is, a lead frame material set on a die is pressed by a stripper bush, and punched by a punch.In a press punching die of a lead frame, the pressing surface of the stripper bush with respect to the lead frame material has a longitudinal direction of the lead. A protrusion is provided over the lead, and a step is provided on the protrusion that presses the tip end side of the lead so as to protrude more than the base side of the lead. In addition, the stepped portion is formed in a plurality of steps in which the tip end side of the lead is low along the longitudinal direction of the lead. Further, a protrusion is provided in the pressing surface of the stripper bush against the lead frame material in the longitudinal direction of the lead, and the protrusion is formed in a tapered surface where the lead tip side is lower. In addition, a protrusion is provided on the pressing surface of the stripper bush against the lead frame material in the longitudinal direction of the lead, and the protrusion is formed with a lead tip portion and a lead base portion in a flat portion, and an intermediate portion of these flat portions is lead. It is characterized in that it is formed in a tapered surface where the tip side is lower.

[0009]

In the die for punching the lead frame according to the present invention, the tip end side is provided by providing the protrusion on the pressing surface of the stripper bush for pressing the lead frame material and the step or taper surface on the protrusion. With respect to the narrow lead, the pressing force is concentrated and supported up to the tip side. As a result, it is possible to prevent the lead from being twisted or rich during punching, and to manufacture a highly accurate lead frame product.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view showing the configuration of a first embodiment of a die for punching a lead frame according to the present invention. The figure shows a side view of a portion where the stripper bush 10 presses the lead frame material 5 with the die 9. The stripper bushing 10 of the present embodiment also has a projection 12 that abuts the lead frame material 5 on the pressing surface of the stripper bushing 10 as in the above-mentioned conventional example, and the feature is that the tip side of the lead to be formed is pressed down. The part is made to further project from the base side of the lead, and the step part 14 of one step is formed.
Was formed.

Since the amount of protrusion of the step portion 14 from the pressing surface of the stripper bush 10 is larger than that of the lead base side, when the lead frame material 5 is pressed by the stripper bush 10, the pressing force of the step portion 14 is more concentrated. However, it is possible to firmly press the lead frame material 5. Since the inner lead of the lead frame becomes narrower toward the tip, the step portion 14 is provided on the projection 12 provided on the stripper bush 10 as described above, and thus the lead frame material 5 is preferably used even if the lead width is narrowed.
Therefore, it is possible to perform the punching process without the twisting and richness of the lead caused by the press punching process.

In the above embodiment, the stepped portion 14 provided on the protruding portion 12 of the stripper bush 10 has one step. However, a plurality of stepped portions are provided in a stepwise manner in the longitudinal direction of the protruding portion 12 so as to extend in the longitudinal direction of the lead. It is also possible to surely press the entire lead by changing the pressing force of the protrusion 12.

As a second embodiment, FIG. 2 is characterized in that the pressing surface of the projection 12 provided on the stripper bush 10 is formed into a tapered surface 15 where the tip end side of the lead is gradually lowered. The effect of changing the protrusion amount of the protrusion 12 is the same as that of the above-described embodiment, and the lead frame material 5 can be firmly held by increasing the pressing force of the protrusion 12 on the tip side of the lead. It is an object.

The method of forming the pressing surface of the protrusion 12 into a tapered surface as in this embodiment is characterized in that the lead can be reliably supported over the entire length of the lead. That is, since the inner lead gradually becomes narrower from the base portion to the tip side, it is preferable to concentrate the pressing force more in the narrow portion according to the lead width. By making the pressing surface of 12 a tapered surface, the entire lead can be held accurately.

FIG. 3 shows a third embodiment in which the stripper bush 10 is provided with a projection 12, and the projection 12 has a flat surface 16a, 16b on the tip side and a base side, and a tapered surface 17 having a lower end on the middle side. It is characterized by being formed. Also in this embodiment, the taper surface 17 is gradually lowered toward the tip end side of the lead, so that the pressing force of the stripper bushing 10 acts evenly over the entire lead, and the lead can be surely pressed and supported, and at the same time, the tip side. Also, the flat portions 16a and 16b are provided on the base side to increase the pressing force at the base position and at the tip end. It is also effective to make the pressing surface flat as described above for the portion where the lead width does not change at the base position and the tip of the lead.

When the die for punching the lead frame according to the present invention is used, the stripping of the lead frame material is ensured by the stripper bushing, and the lead frame material is pulled in and twisted during punch punching. It is possible to prevent punching and perform accurate press punching. As a result, it becomes possible to manufacture a lead frame product having leads of higher density and narrower width than ever before. The die for punching a lead frame according to the present invention can be applied to the production of lead frames having various patterns. The shape and the tapered surface of the protrusion provided on the stripper bushing 10 can be adjusted according to the lead shape, the lead width, and the like. The inclination and the like can be appropriately set and applied.

[0017]

According to the die for punching a lead frame according to the present invention, as described above, the lead frame material can be reliably pressed by the stripper bushing, and the lead frame can be manufactured more easily by the die for pressing. It has a remarkable effect that it can be performed accurately.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a configuration of a first embodiment of a die for punching a lead frame.

FIG. 2 is an explanatory diagram showing a configuration of a second embodiment of a die for punching a lead frame.

FIG. 3 is an explanatory view showing the configuration of a third embodiment of a die for punching a lead frame.

FIG. 4 is an explanatory view showing a configuration of a conventional example of a die for punching a lead frame.

FIG. 5 is an explanatory diagram showing a configuration of a conventional example of a die for punching a lead frame.

FIG. 6 is an explanatory view showing a state where a lead frame material is pressed by a stripper bush in a conventional example of a die for punching a lead frame.

FIG. 7 is a plan view showing how the lead frame material is press-punched.

FIG. 8 is an explanatory view showing a state where a lead frame material is press-punched with a conventional press-punching die.

[Explanation of symbols]

5 Lead frame material 6 blank part 8 punches 9 dies 10 stripper bush 12 Projection 14 Step 15 Tapered surface 16a, 16b Flat part 17 Tapered surface

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Claims (4)

(57) [Claims] 1. A press punching die for a lead frame, wherein a lead frame material set on a die is pressed by a stripper bush and press punched by a punch, wherein a lead is provided on a pressing surface of the stripper bush against the lead frame material. And a step portion projecting from the base side of the lead is provided in the projection that presses the lead tip side, and a die for press-working a lead frame. 2. The die for punching a lead frame according to claim 1, wherein the step portion is formed in a plurality of steps in which the tip end side of the lead is lower along the longitudinal direction of the lead. 3. A die for punching a lead frame, wherein a lead frame material set on a die is pressed by a stripper bush and press punched by a punch, wherein a lead is provided on a pressing surface of the stripper bush against the lead frame material. A die for punching a lead frame, characterized in that a protrusion is provided in the longitudinal direction of the lead frame, and the protrusion is formed on a taper surface where the lead tip side is lower. 4. A press-molding die for a lead frame, wherein a lead frame material set on a die is pressed by a stripper bush and press-punched by a punch, wherein a lead is provided on a pressing surface of the stripper bush against the lead frame material. A protrusion is provided in the longitudinal direction of the lead, the lead tip and the lead base are formed in a flat portion, and an intermediate portion of these flat portions is formed in a tapered surface where the lead tip side is lower. Frame die without press.