JP3313688B2 - Lead cutting die and lead cutting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for cutting and removing the tip of a molded external lead when molding an external lead of a semiconductor device packaged on a lead frame by a resin mold or the like. The present invention relates to a lead cutting die and a lead cutting method.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of a semiconductor device,
After the semiconductor chip mounted on the lead frame is resin-molded, there is a step of cutting and separating the resin-molded package from the lead frame. Then, before performing the cutting and separation, a molding process of an external lead derived from the package is performed.

When performing this external lead forming process,
First, disconnect all of the multiple external leads that are led out of the resin mold package and connected to the lead frame from the connection with the lead frame in advance, and make sure that the resin mold package is connected to and supported by the lead frame with only hanging leads. Keep it.

The lead frame in such a state is set in a lead forming die, and external leads are subjected to, for example, a gull wing type bending process. Next, an extra length of the leading end portion of the external lead previously cut off from the lead frame is removed, and an external lead cutting process is performed to make the leading end dimensions of the lead forming portion uniform.

[0005] A cutting step for trimming the end portions of the formed external leads will be described with reference to the drawings. FIGS. 4A to 4D are process charts for cutting a molded lead using a conventional lead cutting die. FIGS. 4A to 4D show the order of the steps.

In FIG. 4, first, in a step (a), a lead frame 4 having a package 5 in which external leads 6 are formed in advance is conveyed into a lead cutting die.
The package 5 is placed on the work receiver 3 and positioned,
3 shows a state in which the external lead 6 is sandwiched between the work receiver 3 and the cutting punch 1. Lead frame 4 at this time
Has a package 5 sealed with a resin mold or the like.
Are in a state of being supported by the lead frame 4 only by the suspension leads (not shown).

Next, in step (b), the work receiver 3 and the cutting punch 1 are lowered together with the external lead 6 sandwiched therebetween, and the external leads are fixed by the fixed cutting die 2 and the lowered cutting punch 1. Bite the tip of 6. At this time, the tip of the external lead 6 that becomes cutting waste is in a state of rising upward.

Next, in step (c), when the work receiver 3 and the cutting punch 1 are further lowered with the external lead 6 being sandwiched therebetween, the tip of the external lead 6 is cut by the cutting punch 1 and the cutting die 2, and the cutting waste is cut. Reference numeral 7 denotes a state in which the cut surface is in close contact with the cutting blade surface 12 of the cutting punch 1.

Next, in step (d), after cutting the external lead 6, the work receiver 3 and the cutting punch 1 are raised and returned to the initial positions, and the cycle of the lead cutting step is completed.
However, since the cutting chips 7 rise while adhering to the cutting edge surface 12 of the cutting punch 1, a method of discharging the cutting chips 7 by performing air blowing or dust collection by a dust collector before starting the next cycle is adopted.

As shown in FIGS. 4 (a) to 4 (d), the structure of the conventional cutting punch used for cutting the external lead has a cutting blade surface of the cutting punch 1 which meshes with the cutting die 2. As shown in FIGS. 12 has a structure in which it extends vertically beyond the length required for meshing (the cutting edge length) and further upwards as it is, and no measures are taken to eliminate the cutting debris 7. Not.

[0011]

In this conventional lead cutting die, the leading end of the external lead is pinched between the work receiver and the cutting punch with the leading end of the external lead remaining free. And there is no mechanism for pressing down the generated cutting waste or peeling off the cutting waste. For this reason, at the time of cutting, the cutting chips have a shape in which the shearing surface is pushed up by the cutting die along the cutting punch cutting surface while rubbing the cutting surface of the cutting punch.

As a result, a phenomenon occurs in which the cutting debris bites the shavings while being rubbed by the cutting punch cutting edge surface, and a phenomenon in which the adhesive force is strengthened occurs, and a situation in which the cutting debris is not discharged even by air blow or dust absorption occurs. I was

According to the present invention, when cutting and removing the front end portion of a molded external lead of a package resin-molded on a lead frame, cutting dust is prevented from adhering to the cutting blade surface of the cutting punch. It is another object of the present invention to provide a lead cutting die and a lead cutting method capable of easily discharging cutting waste.

[0014]

Lead cutting die of the present invention SUMMARY OF THE INVENTION are sandwiched outer leads of the resin mold package on a lead frame with the work receiving the cutting punch, clamping
In a lead cutting die used for removing the tip of the external lead as cutting waste with the cutting die and the cutting punch while being inserted, a step is provided on the cutting blade surface of the cutting punch, and The corner portion may be a fulcrum against which the cutting chips come in contact with the external lead.

The cutting punch has a tapered surface on its outer surface starting from the fulcrum. The cutting punch and the cutting die bite into the external lead, and at the same time, the tip of the external lead rises upward. The tip of the external lead is brought into contact with the tapered surface.

Further, the cutting punch has a vertical surface on its outer surface starting from the fulcrum, and the cutting punch has an obtuse angle at a fulcrum. Further, the cutting punch is characterized in that a corner serving as a fulcrum is a right angle.

Further, according to the lead cutting method of the present invention, an external lead of a package resin-molded on a lead frame is sandwiched between a work receiver and a cutting punch .
In a lead cutting method for removing the tip of the external lead as cutting debris with a cutting die and the cutting punch, a cutting that is pushed up to a cutting die while being attached to a cutting blade surface of the cutting punch as the bite amount of the cutting punch increases. Debris is rotated around the fulcrum against the fulcrum, characterized by separating the cutting debris that has adhered to the cutting blade surface of the cutting punch from the cutting punch, and after separating the cutting debris from the cutting punch, The cutting chips are discharged by air blow or suction means.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a main part of a lead cutting die according to one embodiment of the present invention.

As shown in FIG. 1, the lead cutting die of the present invention mounts and positions a resin-molded package 5 and is installed so as to surround the work receiver 3 which can move up and down. And a cutting punch 1a that sandwiches the external lead 6 of the package 5 in the work receiver 3 and descends with the work receiver 3 to cut and remove the tip of the external lead 6.

Here, the package 5 mounted on the work receiver 3 is resin-molded on the lead frame 4 in advance, and the outer leads 6 are cut into the gull wing shape in advance by cutting off the tips from the lead frame 4. The package 5 is processed, and is connected to the lead frame only by the suspension leads (not shown).

The cutting punch 1a has a cutting edge surface 12 having a blade edge length L at a front end portion between which the external lead 6 is sandwiched, and a step 9 provided at a position from the front edge 8 to the blade edge length L. Further, the step portion 9 has a corner portion serving as a fulcrum 10 for rotating by being hit by the cutting waste, and a tapered surface 11 having a taper angle θ is provided starting from the fulcrum 10. Further, it is preferable that the cutting edge length L is set to the minimum length necessary for cutting the external lead 6 in order to reduce the stroke of the cutting punch.

Next, the operation of the lead cutting die according to the present embodiment will be described. FIGS. 2A to 2C are views for explaining a lead cutting operation using a lead cutting die of the present invention, and FIGS.

First, as shown in FIG. 1A, a lead frame 4 having a package 5 in which a semiconductor chip is resin-molded in advance and external leads 6 are formed is prepared, and this lead frame 4 is cut with a punch. The package 5 is conveyed into a lead cutting die composed of the cutting die 1a and the cutting die 2, and is placed on the work receiver 3 to position the package 5. Next, the cutting punch 1a is lowered, and the work receiving 3
Sandwiches the external lead 6 with. At this time, the external leads 6
The portion that becomes the cutting waste at the tip of the cantilever protrudes from the sandwiched position.

Next, as shown in FIG. 2B, the cutting punch 1a and the work receiver 3 are lowered together in this sandwiched state. Cutting die 2 fixed as it descends
And the cutting punch 1a descending begin to bite into the external lead 6, and the tip of the external lead 6 rises upward. The raised tip comes into contact with the tapered surface 11 of the cutting punch 1a. As the descent further proceeds and the biting amount of the cutting punch 1a increases, the distal end portion of the external lead 6 is cut into cutting chips, and at this time, the cutting surface adheres to the cutting surface 12 of the cutting punch 1a. As a result, the cutting waste does not fall and remains attached to the tapered surface 11.

Next, as shown in FIG. 3 (c), as the amount of the cutting punch 1a biting into the cutting die 2 further increases, the cutting waste 7 is pushed up by the cutting punch 2, and the cut is pushed up. The waste 7 is rotated around the fulcrum 10 by a fulcrum 10 provided on the cutting punch 1a. By this rotation, the cutting chips 7 are removed from the cutting surface 12 of the cutting punch 1a.
Then, it floats away from the tapered surface 11, and the raised portion is dropped by air blow or suction or the like.

As described above, the cutting punch according to the present embodiment is provided with the fulcrum, so that the cutting chips can be prevented from adhering to the cutting punch. further,
Various leads can be cut by changing the blade edge length L and the taper angle θ of the cutting punch as shown in FIG.

Next, another embodiment of the lead cutting die of the present invention will be described with reference to the drawings. FIG. 3 is a partial cross-sectional view of a lead cutting die for explaining another embodiment of the present invention.

As shown in FIG. 3, in the lead cutting die of the present embodiment, the package 5 is formed by resin molding or the like, and the lead frame 4 on which the external leads 6 are formed is carried in, and the package 5 is mounted. A work receiver 3 that can be placed and positioned and that can move up and down, a cutting punch 1b that sandwiches the external lead 6 between the work receiver 3 and can move up and down together with the work receiver 3, and is installed so as to surround the work receiver 3. And a cutting die 2 for cutting the tip of the external lead 6 with the cutting punch 1b descending.

The cutting punch 1b used in this embodiment is
The cutting punch 1a in the above-described embodiment is a fulcrum 10
In contrast to the tapered surface 11 having the starting point as a starting point, a fulcrum 10 is provided by providing a simple corner instead of the tapered surface.

Next, the operation of this embodiment will be described. As shown in FIG. 3, first, the cutting punch 1 b is lowered, and the external lead 6 is sandwiched between the cutting punch 1 b and the work receiver 3. The cutting punch 1b and the work receiver 3 are lowered together in this sandwiched state. As it descends, the fixed cutting die 2 and the descending cutting punch 1b begin to bite into the external lead 6, and the tip of the external lead 6 rises upward.

The raised tip is the cutting punch 1
abuts on the fulcrum 10 of b. As the descent further proceeds, the amount of bite between the cutting die 2 and the cutting punch 1b increases, and the tip of the external lead 6 is cut off to form cutting chips, which adhere to the cutting surface 12 of the cutting punch 1b. It remains. . Thereafter, when the bite amount further increases, the cutting waste rotates by the action of the fulcrum 10, and separates from the cutting punch 1b. This separation step is the same as in the first embodiment.

As described above, the cutting punch 1a in the above-described embodiment has an obtuse angle at the corner of the fulcrum 10, whereas the fulcrum 10 of the cutting punch 1b in the present embodiment has a right angle. The effect of rotating the debris is increased, so that the debris is more effectively separated from the cutting punch. At this time, the angle of the fulcrum 10 may be set to an arbitrary angle instead of a right angle.

Further, as shown in FIG. 3, the position of the fulcrum 10 is changed by changing the blade edge length L and the width of the stepped portion 9 as shown in FIG. It becomes possible to apply to.

[0034]

According to the lead cutting die and the lead cutting method of the present invention, a step is provided on a cutting blade surface of a cutting punch, and a corner of the step is used as a fulcrum. When cutting and removing the tip of the external lead of the package, the cutting debris that has been in close contact with the cutting blade surface of the cutting punch rotates on the fulcrum and floats away from the cutting surface, so that the cutting debris adheres to the cutting punch. Can be prevented. As a result, the detached cutting waste can be easily discharged by air blow, suction, or the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of a lead cutting die according to an embodiment of the present invention.

FIGS. 2A to 2C are views for explaining the operation of a lead cutting die according to an embodiment of the present invention, wherein FIGS.

FIG. 3 is a partial cross-sectional view showing a lead cutting die according to another embodiment of the present invention.

FIG. 4 is a view for explaining the operation of a conventional lead cutting die;
Figures (a) to (d) show the order of steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a, 1b Cutting punch 2 Cutting die 3 Work receiver 4 Lead frame 5 Package 6 External lead 7 Cutting debris 8 Cutting edge 9 Stepped portion 10 Support point 11 Tapered surface 12 Cutting surface

Claims (7)

(57) [Claims] An external lead of a package molded with resin on a lead frame is sandwiched between a work receiver and a cutting punch, and when the cutting die and the cutting punch remove the tip of the external lead as cutting waste while being sandwiched. In the lead cutting die to be used, a step is provided on a cutting blade surface of the cutting punch, and a corner of the step is used as a fulcrum against which the cutting chips are hit when being cut from an external lead. Mold. 2. The cutting punch has a tapered surface on the outer surface starting from the fulcrum. The cutting punch and the cutting die bite into the external lead, and at the same time the tip of the external lead rises upward. 2. The lead cutting die according to claim 1, wherein the tip of the external lead is brought into contact with the tapered surface. 3. The lead cutting die according to claim 1, wherein the cutting punch has a vertical surface starting from the fulcrum on an outer surface thereof. 4. The lead cutting die according to claim 1, wherein the cutting punch has an obtuse angle at a corner serving as a fulcrum. 5. The lead cutting die according to claim 1, wherein the cutting punch has a right angle at a corner serving as a fulcrum. 6. A lead cutting method in which an external lead of a package resin-molded on a lead frame is sandwiched between a work receiver and a cutting punch, and the tip of the external lead is removed as cutting waste with a cutting die and the cutting punch while being sandwiched. In the method, as the bite amount of the cutting punch increases, the cutting chips pushed up to the cutting die while being attached to the cutting edge surface of the cutting punch are rotated around the fulcrum against the fulcrum, and adhered to the cutting edge surface of the cutting punch. A lead cutting method, wherein separated cutting waste is separated from a cutting punch. 7. The lead cutting method according to claim 6, wherein after separating the cutting chips from the cutting punch, the cutting chips are discharged by air blow or suction means.