JPH0810740B2 - Lead frame manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lead frame, and more particularly to a method for manufacturing a lead frame molded by press working.

(Conventional technology and its problems) To mold the lead frame by press working,
A band-shaped member, which is a lead frame material, is sequentially fed by a progressive die, and the final shape is obtained by sequentially punching each lead frame shape portion to be obtained.

In this way, punching is performed sequentially for each lead frame-shaped portion to obtain the strip-shaped member, because the lead shape is complicated and the lead width is becoming extremely small due to the increase in the number of pins. Due to various circumstances, the punch and die of the punching die are complicatedly arranged, and the stress needs to be dispersed in order to prevent the lead portion from being deformed by the internal stress after punching.

For example, in order to punch-mold the inner lead portion and the stage portion adjacent thereto, first the inner lead portion 10 is formed as shown in FIG. 2 (a), and then the stage portion 12 is formed as shown in FIG. 2 (b). Processing for forming the tips of the internal lead portions 10 is performed.

By the way, depending on the lead frame, there are cases where the shape of the lead portion does not change and only the size of the stage portion 12 differs.

In such a case, it is possible to perform press working on the same progressive die line by leaving the punching die portion such as the lead portion as it is and only replacing the punching die portion of the corresponding stage portion. It is convenient.

However, when the shape of the stage portion 12 is large, the punching line A that determines the edge of the stage portion should be caught in the punching hole B of the internal lead portion 10 punched in the previous step, as shown in FIG. 2 (c). There is. Then, a rectangular or trapezoidal small scrap piece 14 is cut out between the above-mentioned punching line A and the punching line C that determines the tip of the internal lead portion 10, and this small scrap piece 14 is die hole 16 (Fig. 3).
It will fall inside.

If this small scrap piece 14 falls into the die hole 16 as it is and is collected, there is no problem.

However, since the punch of the punching die is operated at a high speed of about 300 times per minute, when the punch is lifted after punching, the inside of the die hole 16 becomes a negative pressure, and the small scrap piece 14 is lightweight, so this negative pressure causes It is sucked up and enters between the die and the work material, and in the next punching process, this small scrap piece
There is a problem that 14 causes dents and scratches on the back surface of the material and damages the punch or die.

More specifically, as shown in FIG. 3, the die hole 16 has a narrow shape with the punched shape as it is and an expanded bottom portion. Therefore, if the small scrap piece 14 falls horizontally in the die hole 16, even if the small scrap piece 14 is sucked upward by the above-mentioned negative pressure, it is caught by the narrow upper wall surface of the die hole 16 and sucked up to above the die. There is no such thing. However, the small scrap pieces 14 drop in the die hole 16 while being inclined from the horizontal state, and are extremely easy to move because the side of the punch hole B is a void, and when sucked by the negative pressure described above, the inner wall of the die hole 16 is small. It may be sucked up as it is without collision.

Therefore, in the conventional case, there are the above-mentioned problems,
When molding a lead frame having a large stage portion, even if the shape of other lead portions and the like is not changed at all, another dedicated progressive die that does not cause the small scrap pieces 14 described above is used. I had to work together.

Therefore, the present invention has been made to solve the above problems, and an object thereof is to prevent dents and scratches from being caused by small scrap pieces, and to not damage the punching die, and It is an object of the present invention to provide a method of manufacturing a lead frame in which a small stage part and a large stage part can be molded by a common progressive die.

(Outline of the Invention) The present invention has the following configuration in order to solve the above problems.

In a method of manufacturing a lead frame, in which a strip-shaped member is sequentially punched by a progressive die to form a lead frame including an internal lead portion and a stage portion, a part of an end side of the stage portion is formed on the strip-shaped member. After punching out the punched hole to form the internal lead portion whose tip is connected to the stage portion, a punching line and a stage for determining the internal lead portion and the tip are formed in the vicinity of the connecting portion of the internal lead portion with the stage portion. The punching line for deciding the remaining edge of the inner portion of the inner lead portion and the edge of the stage portion opposite to the leading edge so as to be non-linear. It is characterized by forming.

(Embodiment) A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a partial explanatory view showing an example of the lead frame 20 according to the present invention. In the present invention, the lead frame 20
It is characterized by the shape of the tip of the inner lead portion 22 and the shape of the side of the stage portion 24 facing the inner lead portion 22. The other parts of the lead frame 20 are not particularly different from the conventional shape, and thus the illustration and description thereof are omitted. Reference numeral 26 indicates a stage support bar.

The planar shape of the tips of the inner lead portions 22 of the lead frame 20 shown in FIG. 1 is recessed in a shallow V shape, and each side portion of the stage portion 24 facing this is also recessed in a shallow V shape. There is. As described above, in order to form the tip shape of the inner lead portion 22 and the shape of the side of the stage portion 24 facing the inner lead portion 22 into a shallow V shape, the corresponding punch and die of the punching die have a shallow V shape. Needless to say, it is provided in a letter shape and punched.

Internal lead part 22 of lead frame 20 and stage part
When punching out 24, the punching hole X for forming the inner lead portion 22 is first formed as in the conventional case, and then punching processing for determining the outer shape of the stage portion 24 and the tip of the inner lead portion 22 is performed. Therefore, as in the above, the stage section 24
When the punching line Y of FIG. 2 forms a large stage portion 24 that extends over the punching hole X, a small scrap piece 28 protruding in a V-shape with shallow ends at both ends is formed as shown in the drawing, and the small scrap piece 28 corresponds to the die. It will fall into the hole.

When this small scrap piece 28 falls in the die hole, the shallow V-shaped projecting portions at both ends are guided by the inner wall of the die hole which is correspondingly recessed in the V-shape to keep a substantially horizontal state. Even if it is dropped and sucked upward by negative pressure as described above, the small scrap piece 28 does not move to the side of the punching hole X, so it is regulated by the inner wall of the narrow die hole and sucked up above the die. There is no such thing.

The small scrap piece 28 drops while keeping the inside of the die hole substantially horizontal, for example, in the figure, the small scrap piece 28 rotates around one straight part and the other straight part side falls to form a slope. At this time, it will be apparent from the fact that the V-shaped side is restricted by the inner wall of the die hole to prevent the above-described rotation.

The shape of the tip of the inner lead portion 22 and the shape of the side of the stage portion 24 facing the inner lead portion 22 are not limited to the above, and are arcuate and shallow U.
It may have a letter-like shape, and the point is that the inner lead portion 22 has a concave or convex shape or a concave and convex portion with respect to a line connecting both widthwise ends of the inner lead portion 22. . That is, it may have a non-linear shape. Stage part 24
The shape of the side of the portion facing the tip of the inner lead portion 22 is also the same.

(Effects of the Invention) As described above, according to the method of manufacturing the lead frame of the present invention, the internal lead portion formed in advance has the stage portion having a large shape, and the punching line that determines the edge of the stage portion is formed. Even if a small scrap piece occurs between the tip of the internal lead part and the edge of the stage part due to press working, the small scrap piece falls in the die hole while keeping it substantially horizontal. However, even if it is sucked upward by the negative pressure generated in the die hole by the high speed operation of the punch, it is not sucked up from the die hole.

Therefore, there are no dents or scratches, damage to the punch or die, and even if the stage has a smaller shape or a larger shape, the corresponding punching die part Provided is a method of manufacturing a lead frame, which can be manufactured in the same progressive mold by simply replacing the lead frame.

Although the present invention has been variously described with reference to the preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. Is.

[Brief description of drawings]

FIG. 1 shows an embodiment of a lead frame according to the present invention, and is an explanatory view of the shapes of the inner lead end and the stage end. 2 (a), (b), and (c) are explanatory views showing a conventional punching process in the vicinity of the internal lead portion and the stage portion, and FIG. 3 is an explanatory view of the shape of the die hole. 10 …… Internal lead, 12 …… Stage, 14 …… Small scrap piece, 16 …… Die hole, 20 …… Lead frame, 22 …… Internal lead, 24 …… Stage, 26 …… Stage support Bar, 28 ... Small scrap pieces.

Claims (1)

[Claims] 1. A method of manufacturing a lead frame, wherein a strip-shaped member is sequentially punched by a progressive die to form a lead frame having an internal lead portion and a stage portion. After punching out a hole forming a part to form the internal lead portion whose tip is connected to the stage portion, the punching for determining the tip of the internal lead portion is performed in the vicinity of the connection portion of the internal lead portion with the stage portion. Both the line and the punching line that determines the remaining edge of the stage part are punched out over a predetermined width so as to cover the punched hole, and the tip of the internal lead part and the edge of the stage part facing the tip are not cut, respectively. A method for manufacturing a lead frame, which is characterized in that the lead frame is formed in a linear shape.