JPH0917931A - Lead frame making die unit - Google Patents

Abstract

PURPOSE: To increase an effective wire width of an inner lead top end part to obtain a lead frame high in reliability without position slippages by a method wherein punching is performed under conditions that an area is pressed which is an inner lead that one side edge is punched by a material pressing piece fixed into a stripper. CONSTITUTION: This embodiment comprises a die 2 which has a first opening C1, and on which a slit material 1 is placed; a pressing stripper 3 that a second opening C2 is arranged; and a punch 4 which is inserted into second and first openings, to press a portion of the slit material 1. The stripper 3 is provided with a material pressing piece which 5 approaches the punch inserting second opening C2 and projects to the die 2 side. Under conditions that an area in which one inner lead 11 side edge is punched, and which is an inner lead 11 of the slit material 1 is pressed on the die 2 by the material pressing piece 5, another side edge of the inner lead 11 is punched. Thus, specific intervals can be obtained and a lead frame high in reliability without distortions can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device for manufacturing a lead frame, and more particularly to a pressing structure for the mold device.

[0002]

2. Description of the Related Art With the miniaturization, thinning and high integration of semiconductor devices, the lead width, lead spacing and thickness of the lead frames used for these devices are becoming smaller and smaller. Is required.

The lead frame used for mounting such a semiconductor device is formed by stamping or etching a band-shaped metal material (strip material) such as iron or copper into a desired pattern. Formed by.

In particular, for the lead frame formed by stamping, all the inner leads are
Since it is difficult to mold in a single punching process, the lead is designed to be divided into a plurality of stations for punching.

However, in the recent lead frame, the lead pitch tends to be narrower than the plate thickness of the inner lead tip portion.
Punching may have to be done with a width of ~ 0.12 mm.

When a minute lead frame is divided into a plurality of stations by the stamping method and punched out, the punched and thinned one cannot be pressed sufficiently and is already punched out to be in a free state. It is becoming more common to see a phenomenon in which the adjacent inner leads are twisted and the cross section of the inner leads is distorted, which reduces the bonding area.

In addition, at the most distal end of the inner leads, a method of securing an effective flat width by coining is often used. However, if the coining amount is too deep because the inner lead spacing is extremely narrow, the inner leads will be adjacent to each other. This will result in a short circuit accident.

Therefore, a heat treatment for removing the residual strain may be performed, or a process of fixing the inner leads to each other by taping may be performed.
In the case of forming a fine lead frame, there are various problems such as the tip of the inner lead being twisted during these steps, which causes positional displacement.

To solve this problem, the applicant has
As shown in FIG. 5, a method is proposed in which the inner lead side edge is punched while pressing the tip of the inner lead with a protrusion K provided on the stripper 3.

In this method, electric discharge machining is used as a method of forming a protruding portion on the stripper, and the periphery of the protruding portion is scraped off while leaving a portion to be the protruding portion. Since it is machined deeper than the part, the material of the inner lead side edge punching punch is not pressed on the side where the protruding portion is not formed, and the punching operation causes twisting due to retraction.

Further, the height of the protruding portion needs to be adjusted with high precision. Even if the height is slightly high or low, the wall thickness becomes too thin due to excessive pressing, and sufficient pressing cannot be performed, resulting in twisting. It will be lost.

Furthermore, since a large pressing force is applied to the protruding portion, abrasion is likely to occur, and sufficient pressing force cannot be obtained even with slight abrasion.

[0013]

As described above, with the miniaturization of the lead frame, when the side edges are punched out, it is not possible to sufficiently press the lead frame, and therefore, twisting occurs and the position of the inner lead tip is easily displaced. In addition, since it is not possible to easily obtain an inner lead having a favorable tip cross-sectional shape and a sufficient bonding area cannot be obtained, a bonding error or the like frequently occurs, which may cause a decrease in reliability.

Further, a stopper having a protruding portion for pressing is proposed, but the pressing effect cannot be sufficiently exerted even with a slight height deviation, or the thickness is reduced due to excessive pressing. There was also the problem of being lost.

The present invention has been made in view of the above circumstances, and it is possible to increase the effective line width of the inner lead tip portion and provide a highly reliable lead frame without positional displacement. It is an object to provide a mold device having a forming station.

[0016]

Therefore, in the present invention, a die having a first opening corresponding to a punching area and configured to mount a strip, and a punch corresponding to the punching area. A stripper for pressing, in which a second opening for insertion is arranged, and a strip member which is inserted into the second and first openings and which is located in the punched region toward the strip member on the die. A lead frame manufacturing die apparatus for punching the inner lead side edge of the lead frame, wherein the stripper is close to the second opening for punch insertion,
A material pressing piece protruding to the die side is provided, and one side of the inner lead side edge is punched out, and the area for the inner lead of the strip is pressed by the material pressing piece on the die. It is configured such that the side edge on the other side of the lead is punched.

Preferably, the material pressing piece is removably attached to the stripper, is made of a member having a hardness higher than that of the stripper constituent member, and the protruding height from the stripper surface is adjustable. It is characterized by being.

[0018]

According to this structure, since the material pressing piece fixed in the stripper presses the region where one side edge has already been punched out to be the inner lead, punching is performed, so that the inner lead tip portion Can be punched while being sufficiently pressed, and it is possible to obtain a predetermined interval without causing twisting due to the punching load.

Further, since the height of the material pressing piece can be easily adjusted and is detachable, the height can be easily adjusted when the height becomes low due to abrasion.
Further, by constructing the material pressing piece with a material having a high hardness such as tungsten carbide, it is possible to extend the life.

The material pressing piece is mounted so as to come into contact with the inner lead side edge punching punch in a state where the height is adjusted sufficiently, and the inner lead side edge is punched while pressing the strip material. Therefore, it is possible to punch while punching the inner lead tip portion sufficiently, and it is possible to obtain a predetermined interval without causing twisting due to the punching load.

Further, once the material pressing piece is pressed, the plate thickness of the strip becomes small, and the effect of pressing by the material pressing piece convex portion cannot be obtained again. However, in the present invention, the punch is sequentially fed. The material pressing piece is formed so as to come into contact with the punch insertion hole on one side in the direction, so that the material is pressed only on one side in the forward feeding direction. Since it can be formed without pressing, the top exerts a good pressing effect, and it is possible to punch with the inner lead tip part or at least part of the inner lead pressed sufficiently, and twisting may occur due to the punching load. It is possible to obtain a predetermined interval without any need.

Therefore, the coining depth may be shallow,
Since it is possible to minimize the decrease in the inner lead spacing due to coining, it is possible to obtain a highly reliable lead frame without causing a short circuit accident.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mold apparatus for producing a lead frame according to an embodiment of the present invention will be described below.

As shown in FIG. 1, this apparatus has a first opening C1 corresponding to the punching area, and a die 2 configured to mount the strip 1 and a die 2 corresponding to the punching area. And the stripper 3 for pressing in which the second opening C2 for punch insertion is arranged, and the stripper 3 which is inserted into the second and first openings and is directed toward the strip 1 on the die 2,
In a die device for manufacturing a lead frame, which comprises a punch 4 for pressing a portion of the strip 1 located in the punching area and punches the inner lead side edge of the lead frame, the stripper 3 is used for punch insertion. It is characterized in that a material pressing piece 5 protruding toward the die is provided in the vicinity of the second opening.

In this case, one side of the inner lead is punched out, and the area for the inner lead of the strip is pressed by the material pressing piece 5 while the side edge of the other side of the inner lead is pressed. Is punched out. Also,
Here, the material pressing piece 5 is made of tungsten carbide having a high hardness, and is fixed and fixed in the recess of the stripper.

At the time of punching, the protruding height of the material pressing piece 5 is determined according to the thickness of the strip.

FIG. 2 is a schematic explanatory view of the die of this apparatus. Here, for simplification, three inter-lead area punching stations S1 to S3 and a cavity punching station S4 for punching the cavity area at the tip are shown. It consists of four stations. Here, in S1, the region to be the inner lead having one side edge punched out is punched in the other side edge in S2.
At this time, the material is pressed by the material pressing piece 5 attached to the stripper of the present invention, and punching is performed in a good state without twisting.

Next, a lead frame punching method using this mold device will be described. In the figure, the area for punching in that step is defined as a hatched area.

First, as shown by St1 in FIG. 3, a strip-shaped material is formed into an inner lead, an outer lead, and
The first inner lead-leading region 14 is first punched by mounting on a die (not shown) equipped with a die such as a tie bar, and press working to form inner lead side edges on one side. .

Then, in St2, the inter-inner-lead regions 14 are sequentially punched out to form inner lead side edges.

At this time, the strip material is sandwiched between the pressing stripper 3 and the punching die 2 and punching is performed by the punch 4. As shown in FIG. The inner lead side edge is punched out while pressing with the pressed material pressing piece 5. As described above, the material pressing piece 5 provided on the stripper 3 punches out the other side edge so that the inner lead side edge is punched while pressing the area of the inner lead in a semi-free state. It is possible to punch with the tip of the inner lead pressed sufficiently, and it is possible to obtain a predetermined interval without causing twisting due to the punching load. Also,
The surface of the material pressing piece 5 is lapped and is coined at the same time.

Here, although the material pressing top surface is lapped and coined at the same time, it may be used only for pressing. Further, the outer leads 12 are also punched simultaneously with the punching of the inter-lead region of the inner leads 11, but they may be punched in another step.

Then, as shown in St3 of FIG. 3, the cavity region 16 located between the die pad 15 and the inner lead tip is punched out, and as shown in St4, the lead frame is shaped. Then, plating is applied to a predetermined area to complete the lead frame.

The tip portion of the inner lead 1 of the lead frame thus formed can have a predetermined interval without being twisted, and the cross-sectional shape becomes an extremely ideal shape, and the coining amount is shallow. Can also ensure a sufficient effective flat width.

Further, it is possible to minimize the decrease in the inner lead spacing due to coining, and to reduce the occurrence of short circuit accidents.

Furthermore, since the twist of the inner lead is suppressed to the minimum by the above-mentioned device of the punching process of the inner lead tip, the internal residual stress is small,
The tip position of the inner lead can be maintained correctly,
The deviation of the bonding position can be reduced.

Further, in the above-mentioned embodiment, the plating process is carried out after the lead frame is shaped, but it may be carried out during the shaping.

In the above embodiment, the material pressing piece is fitted in the recess of the stripper, but it may be screwed, and the material and shape can be changed as appropriate.

For example, as shown in FIG. 4, the material pressing piece 5 may be fixed to the stripper 3 with a screw 6, and the protrusion height to the die side may be adjusted with the screw.

[0040]

As described above, according to the apparatus of the present invention, when the strip material is processed into the shape of the lead frame, the inner lead side edge is pressed while being pressed by the material pressing piece fixed to the stripper. Since it is punched out, it is possible to obtain a predetermined interval without causing twisting due to the punching load, and it is possible to obtain a highly reliable lead frame without distortion.

[Brief description of the drawings]

FIG. 1 is a mold apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a die of a mold device according to an embodiment of the present invention.

FIG. 3 is a lead frame using the mold apparatus of the embodiment of the present invention.
Explanatory diagram showing the manufacturing process of

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5: Conventional mold device

[Explanation of symbols]

 1 strip material 2 die C1 first opening C2 second opening 3 stripping tool 4 punch 5 punch for material pressing 6 6 screw 11 inner lead 12 outer lead 13 tie bar 14 area between inner leads (equivalent) part 15 die pad 16 Cavity area

Claims (2)

[Claims] 1. A die having a first opening corresponding to a punching area and configured to mount a strip,
A pressing stripper in which a second opening for punch insertion is arranged corresponding to the punching area, and a stripper for insertion into the second and first openings, and toward the strip on the die, A lead frame manufacturing die apparatus, comprising: a punch for punching by pressing a portion of a strip material located in a punching region, wherein the stripper is for punch punching. A material pressing piece protruding toward the die is provided in the vicinity of the second opening, and one of the inner lead side edges is punched out, and the material pressing piece is provided in a region serving as an inner lead of the strip. A lead frame manufacturing die apparatus, wherein a side edge on the other side of the inner lead is punched while being pressed on a die. 2. The material pressing piece is detachably attached to the stripper, is made of a member having a hardness higher than that of the stripper constituent member, and a protruding height from the stripper surface can be adjusted. The mold apparatus for manufacturing a lead frame according to claim 1, wherein.