JP2751908B2 - Tie bar cutting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tie bar portion for connecting leads derived from a resin shell formed by sealing a chip of an electronic device such as a semiconductor device with a resin, and an interposition between the resin shell and the tie bar portion. The present invention relates to a tie bar cutting device for cutting and removing resin burrs.

[0002]

2. Description of the Related Art FIG. 3 is a side view showing an example of a conventional tie bar cutting device. Conventionally, as shown in FIG. 3, this type of tie bar cutting device includes an upper die holder 9 for fixing a punch plate 12, a punch guide 11 for positioning a punch 7 having a flat surface at a tip end, and a punch guide 11 And a spring 14 for applying a repulsive force so as to push the punch guide 11 open from the punch plate 2, the resin 13 and the lead 2.
And a die 8 on which the device 1 is placed.

There are projecting portions on both sides of the die 8, and the punch guide 11 comes into contact with the projecting portions as the upper die descends. Further, the spring 14 is compressed by the lowering of the upper die, and the punch 7 is compressed. The tie bar and the resin flash were lowered and entered the cutting holes of the lower die 8 to cut and remove the burrs. The guide post 15 is provided so that the upper die and the lower die are precisely slid so that the punch 7 and the cut hole of the die 8 always fit precisely.

FIGS. 4 (a) and 4 (b) are a partial plan view and a sectional view of a die for explaining the cutting and removing of a tie bar and a resin burr by the tie bar cutting device of FIG. Next, FIG.
The operation of cutting and removing the tie bar and the resin flash will be described with reference to FIG. 4 and FIG. First, the upper die holder 9 in FIG. 3 is lowered by the operation of the press, and the punch guide 1 is accordingly moved.
1 also falls. When the surface of the punch guide 11 comes into contact with the projecting portion of the die 8, the spring 14 is compressed and the punch 7 projects from the punch guide 11.

Due to the protrusion of the punch 7, as shown in FIG. 4, the punch 7 enters the cutting hole 16 of the die 8 as shown by a broken line, cuts the tie bar 22 connecting the lead 21, and is called a resin dam. The burred resin beam was broken and dropped under the die 8 as a tie bar piece 22a and a resin piece 23a.

[0006] However, in recent years, as the integration and miniaturization of electronic devices have become smaller, the width of leads and their intervals have been increasingly reduced. The apparatus has been improved so that the distance between the resin outer body 20 and the tie bar 22 is made narrower, the length of the resin dam 23 is made as short as possible, and the resin burrs are reduced. Then, the resin outer body 20 is not eroded by the punch 7 so that chipping does not occur.
The position of the punch 7 is determined so that the resin burr is slightly left on the resin outer body 20.

[0007]

FIGS. 5 (a) and 5 (b) are diagrams showing a resin outer shell and leads, and a diagram showing a punch and an electronic device for explaining the problems in the present invention. However, now that the process has been streamlined, the leads are tie-bar cut after plating. Therefore, a new problem was raised.

[0008] This problem is caused by the fact that the soft plated part is not shown in FIG.
As shown in (a), the pressing portion of the punch 7 against the tie bar 22 pushes up the plated portion of the peripheral portion of the lead at the connection portion with the tie bar 22, and the plated portion pushed by the rise of the punch 7 When the punch 7 is adhered, a part of the plated portion is lifted with the rise of the punch 7, and the whiskers 24 are generated so as to pull the thread. The whiskers 24 shorted between the leads 22 resulting in a serious quality defect.

Then, in order to prevent the generation of the whiskers 24, an experiment was conducted by changing the shape of the tip of the punch, and no whiskers were generated. This punch 7
As shown in FIG. 5 (a), the tip of
From the side of 0, for example, 0.1 mm from the position of 0.05 mm
A flat portion 18 having a radius of about 0.8 mm is provided in the direction in which the lead 21 extends from the flat surface 18.

In the process of cutting the tie bar 22 by the punch 7a, the punch 7a comes into contact with the tie bar 22 from the side where the lead 21 extends, and the step 17 gives a rotational moment to the tie bar 22 as the punch 7a descends. While bending 22, both sides are cut with a punch 7 a, and finally the resin is cut at the edge of the flat portion 18. In other words, the pressing force of the punch 7a is dispersed into the force for applying the rotational moment, and the pressing force of the tie bar 22 is reduced directly to prevent the plating from rising at the periphery of the lead, thereby preventing the generation of a whisker.

However, this kind of electronic device is
Many types have different dimensions and shapes, and the R of the step portion of the punch has to be determined according to the width of each tie bar. For this reason, there has been an unreasonable problem in production that devices having corresponding punches must be prepared.

Accordingly, an object of the present invention is to cut and remove a tie bar and a resin burr without generating a whisker of plating even if the width of the tie bar connecting the tie bar derived from the side of the resin outer body of the electronic device changes. An object of the present invention is to provide a versatile tie bar cutting device.

[0013]

SUMMARY OF THE INVENTION A feature of the present invention is that a tie bar portion for connecting a plurality of leads led out side by side from the side of the resin outer shell of the electronic device, the resin outer shell and the tie bar are connected to each other. In a tie bar cutting device for cutting and removing resin burrs interposed therebetween, the tip is formed in a shape having a flat portion on the resin outer body side and a step portion falling from the flat portion in a direction in which the lead extends, and the upper die is formed. A plurality of punches attached via a spring, a die having a cutting hole into which these punches enter and a flat portion on which the lead is placed, and being fixed to a lower die, and While the step portion of the punch abuts on the tie bar portion in the direction in which the lead extends, the tip of the punch is turned inward, the tie bar portion is twisted, and the upper die is lowered. Wherein a tie bar cutting apparatus and a copying mechanism the cause modeled after the downward movement of the punch so as to cut off the flat portion pushing the punch into the cutting hole twisted tie bar portion and the said resin burrs. Further, it is desirable that the shape at which the step portion falls is curved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are a side view of a tie bar cutting device and an enlarged view of a punch according to an embodiment of the present invention. As shown in FIG. 1, this tie-bar cutting device is mounted on an upper die holder 9 via a punch plate 12 by suspending it on a bolt 13b into which a spring 14b is inserted, and having a rotary shaft 5 on both sides. The tip is formed in a shape having a flat portion 1b and a step portion 1a that falls from the flat portion 1b in the extending direction of the lead 21 on the resin outer body 20 side, while being rotatably attached to the rotating shaft 5 of the holder block 2. The punch 1 and a guide roller 4 on the side surface of the punch 1 have a copying surface 3a that slides while contacting with the repulsive force of a preload spring 6, and a spring 14a is inserted into the upper die holder 9 via a punch plate 12. And a punch guide 3 attached with a bolt 13a.

The die 8 fixed to the lower mold holder 10
The guide post 15 is provided in the same manner as in the conventional example. The punch 1 attached to the rotating shaft 5 of the holder block 2 is regulated by the copying surface 3a of the guide roller 4, and its tip is temporarily turned inward by the lowering of the upper die, and furthermore, by the lowering of the upper die. Descend vertically to the die 8.

FIGS. 2A and 2B are views showing the operation of the punch for explaining the operation of the tie bar cutting device of FIG. Next, the operation of the tie bar device will be described with reference to FIGS.
This will be described with reference to FIG. First, when the upper die is lowered and the punch guide 3 of FIG. 1 abuts on the protrusion of the die 8, the spring 14b of FIG. 1 is compressed and the punch 21 presses the lead 21. Further, when the upper die is lowered, the punch 1 and the holder block 2 are lowered.

Then, the punch 1 starts turning as the guide roller 4 is regulated by the copying surface 3a. As shown in FIG. 2 (a), the punch 1 descends while turning, and the step portion 1 a hits the tie bar 22 in the direction in which the lead 21 extends, and gives a rotational moment to the diver 22. Further, as the punch 1 descends, as shown in FIG. 2B, the punch 1 enters the cutting hole 16 and the connecting portion of the tie bar 22 is cut by the side blade of the punch 1 and the side blade of the cutting hole 16. The tie bar 22 is twisted and bent by the turning force and the vertical force of the step portion 1a.

Next, as the punch 1 descends, the guide roller 4 of FIG. 1 slides on the vertical surface of the copying surface 3a, so that the punch 1 stops rotating and is perpendicular to the surface of the die 8. Descend. Then, the flat portion 1b of the punch 1 comes into contact with the resin dam 23, and falls down as a resin piece 23a together with the cut tie bar piece 22a.

As described above, if the punch 1 is turned from the outside of the tie bar 22 to the inside, the tie bar 2
Even if the width of the tie bar 2 is changed, the end of the tie bar 22 in the direction in which the lead 21 extends can always be brought into contact with the stepped portion 1a and the tie bar 22 can be cut while being twisted. As a result, there is no swelling of the plating at the connection portion between the lead and the tie bar, and the yarn is not pulled.

The falling shape of the step portion 1a is as follows:
For a thick tie bar, it may be straight. However, considering that the tie bar becomes thinner, it is desirable that the falling portion be curved. In addition, although the turning operation accompanying the lowering of the punch has been described using the copying mechanism of the guide roller, the present invention is not limited to this mechanism.

[0022]

As described above, according to the present invention, even if the width of the tie bar is changed, the tie bar is always in contact with the tie bar by providing a mechanism for turning the punch inward so as to abut the tie bar from the direction in which the lead extends. Contact and rotation moment can be applied and twisting can be performed, and generation of whiskers such as stringing of plating is eliminated. As a result, according to the present invention, there is an effect that a single punch having a fixed shape can be used regardless of the size of the tie bar width.

[Brief description of the drawings]

FIG. 1 is a side view of a tie bar cutting device and an enlarged view of a punch according to an embodiment of the present invention.

FIG. 2 is a view showing an operation order of a punch for explaining an operation of the tie bar cutting device of FIG. 1;

FIG. 3 is a side view showing an example of a conventional tie bar cutting device.

4A and 4B are a partial plan view and a sectional view of a die for explaining cutting and removing a tie bar and a resin burr by the tie bar cutting device of FIG. 3;

FIG. 5 is a diagram showing a resin outer shell and leads for explaining the problem in the present invention, and a diagram showing a punch and an electronic device.

[Explanation of symbols]

 1, 7, 7a Punch 1a, 17 Step portion 1b, 18 Flat portion 2 Holder block 3, 11 Punch guide 3a Copying surface 4 Guide roller 5 Rotary shaft 6 Preload spring 8 Die 9 Upper die holder 10 Lower die holder 12 Punch plate 13a , 14a Bolt 14a, 14b Spring 15 Guide Post 16 Cutting Hole 20 Resin Outer Body 21 Lead 22 Tie Bar 22a Tie Bar Piece 23 Resin Dam 23a Resin Piece 24 Beard

Claims (2)

(57) [Claims] 1. A tie bar portion connecting a plurality of leads led out side by side from a side of a resin outer body of an electronic device, and cutting and removing a resin beam interposed between the resin outer body and the tie bar. In the tie bar cutting device, a plurality of punches each having a tip formed in a shape having a flat portion on the resin outer body side and a step portion falling from the flat portion in a direction in which the lead extends and being attached to the upper die via a spring. A die having cutting holes into which these punches enter and a flat portion on which the leads are placed, and being fixed to a lower die, and a step portion of the punches extending in a direction in which the leads extend with the lowering of the upper die. The tip portion of the punch is swung inward while abutting on the tie bar portion on the side, the tie bar portion is twisted, and the flat portion is inserted into the cutting hole by lowering the upper die. A tie bar cutting device, comprising: a copying mechanism that imitates the downward movement of the punch so as to push the punch and cut and remove the twisted tie bar portion and the resin beam. 2. The tie bar cutting device according to claim 1, wherein the shape of the step portion falling is curved.