JP2003060147A - Tie bar cut die obtained by making thin plate ultra fine particle super hard material undergo wire cut processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tie bar cut die which is elongated in service life, reduced in price, shortened in delivery time, and improved in easiness of replacement. SOLUTION: A tie bar cut die 1 uses an ultra fine particle super hard material thin plate as a material, edges looking like the teeth of a comb are provided to the tie bar cut die 1 through wire cutting work, a die base 2 supports the edges of the teeth of a comb from below, positioning the tie bar cut die 1 at a regular position, and mounting screws 3 are used to fix the tie bar cut die 1 and the die base 2 together so as to bring the surfaces of the cut die 1 and the die base 2 into close contact with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tie bar cutting die used for cutting a dam bar between outer leads of a lead frame in which a semiconductor is resin-molded.

[0002]

2. Description of the Related Art As shown in FIG. 6, an outer lead 5 of a semiconductor lead frame which is molded with a resin 10 is connected by a dam bar 6, and this dam bar 6 needs to be punched out.

For punching, as shown in FIG. 6, the outer lead 5 is set so as to overlap the comb blade portion of the tie bar cutting die 1, and the dam bar 6 is punched by the tie bar cutting punch 4. After punching, as shown in FIG. 7, the tie bar cut 9 is formed, and the outer leads 5 are separated.

As shown in FIG. 8, a conventional tie bar cut die 11 used for punching has a comb blade formed by wire cutting on a cemented carbide block. Alternatively, as shown in FIG. 9, each of the divided ultrafine particle cemented carbide materials was combined with a tie bar cut die 11 in which a comb blade was formed by grinding with a blade.

[0005]

However, both of the tie bar cutting dies 11 need to be integrally molded from the sintered body of the material, and the unit price is high.

The tie bar cutting die 11 shown in FIG.
Since microcracks are remarkably generated on the processed surface when wire cutting is performed on ultrafine cemented carbide, a superhard material that is less affected by microcracks is selected as the material. However, since the hardness is far inferior to that of the ultrafine particle cemented carbide material, wear of the tie bar cutting edge easily progresses as the punching increases, and burrs, which is a fatal problem, occur on the tie bar cutting surface. In this case, it will be replaced with a new one.
Further, the microcracks grow as the number of punches increases, and as shown in FIG. 10, cracks 12 occur at the root of the comb blade and the comb blade falls off. This will result in defective tie bar cutting.

In the case of the tie bar cutting die 11 shown in FIG. 9, the ultrafine cemented carbide material is ground with a blade to form a comb blade. For this reason, the problems with respect to wear and cracks can be solved, but since the grinding process takes a lot of time, the unit price becomes very high and the delivery time becomes very long.

As described above, in dam bar cutting, there are problems in improving the service life of the tie bar cutting die, lowering the unit price, and shortening the delivery time.

When the conventional tie bar cutting die 11 shown in FIGS. 8 and 9 is replaced, the mold must be disassembled and taken out, a new one is assembled, and a new work must be carried out. . Depending on the skill level, normal quality may not be obtained.

[0010]

As a means for solving the above problems, as shown in FIG. 1, the present invention uses a thin plate of ultrafine particle superhard material as a material and a tie bar formed by wire cutting a comb blade. Cut die 1, tie bar Cut die 1
Provided is a tie bar cut die which comprises a die base 2 for supporting and supporting the comb blade from below while positioning at a normal position, and a mounting screw 3 for fixing and closely adhering these surfaces.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiment of the present invention is, as shown in FIG. 2, a tie bar cut in which a comb blade is formed by wire cutting on a thin plate having a thickness of about 1.0 mm made of ultrafine cemented carbide material. The die 1 has a comb blade that is smaller than the cutting edge shape of the comb blade of the tie bar cutting die 1 by about 0.03 mm, and is attached to the upper surface of the die base 2 made of hardened steel by the mounting screw 3. Fix it. The die base 2 has a spigot so that the tie bar cutting die 1 is in a normal position, and has a structure in which the tie bar cutting die 1 is fitted.

FIG. 3 shows a state immediately before cutting. Cutting starts when the tie bar cut punch 4 contacts the dam bar 6, but the cutting force and the cutting resistance force of the tie bar cutting die 1 are
It acts as a load on the comb blade. Furthermore, since the tie bar cut die 1 is in close contact with the die base 2, the load force is similarly applied to the die base 2. However, when the die base 2 is made of hardened steel as a material, it has a rigidity that can cope with the above-mentioned load force, and since it absorbs a negative overforce, the tie bar cut die 1 has a strength equivalent to that of the die base 2. You've got it. That is, it is possible to prevent the growth of microcracks existing at the root portion of the comb blade of the tie bar cutting die 1. The present invention combines the tie bar cut die 1 made of thin ultrafine particle cemented carbide material and the die base 2 made of hardened steel material to have the same ability as the split type conventional tie bar cut die 11 shown in FIG. It will be. FIG. 4 shows the state immediately after cutting. The comb blade of the die base 2 is made thinner than the comb blade of the tie bar cut die 1 by about 0.03 mm, and the cut dambar cut piece 7 falls without remaining in the groove of the die base 2.

As shown in FIG. 5, a tie bar cut die 1
A plurality of positioning pins 8 may be provided on the die base 2 as normal positioning means for the die base 2 to have a shape to be fitted into a hole formed in the tie bar cut die 1.

[0014]

As described above, (a) the tie bar cutting die 1 according to the present invention is equivalent to the conventional split type tie bar cutting die 11 in spite of using a thin plate ultrafine particle cemented carbide material. A long life can be obtained. (B) The tie bar cutting die 1 according to the present invention uses a thin plate of ultrafine particle cemented carbide material, which can significantly reduce the volume of material used as compared with the conventional tie bar cutting die 11 and can burn the material. Does not require integral molding at the time of binding. Further, the comb blade processing by the wire cutting processing of the tie bar cutting die 1 can simultaneously process a plurality of sheets. The die base 2 can be created only at the first time and used repeatedly.
From the above points, the unit manufacturing cost can be made much lower than in the past, and the delivery time can be shortened significantly. (C) When replacing the tie bar cut die 1, the normal position can be determined simply by loosening the mounting screw 3 and removing it without disassembling the mold, and then fitting a new one into the die base 2.
After that, just tighten the mounting screw 3 to complete. It requires no skill and can be completed in a short time.

[Brief description of drawings]

FIG. 1 is a perspective view of claim 1 of the present invention.

FIG. 2 is an enlarged perspective view of claim 1 of the present invention.

FIG. 3 is an enlarged view showing a state immediately before tie bar cutting.

FIG. 4 is an enlarged view showing a state immediately after tie bar cutting.

FIG. 5 is an enlarged perspective view of claim 2 of the present invention.

FIG. 6 is a perspective view showing a state before tie bar cutting.

FIG. 7 is a perspective view showing a state after tie-by cutting.

FIG. 8 is a perspective view of a conventional block type tie bar cutting die.

FIG. 9 is a perspective view of a conventional split type tie bar cut die.

FIG. 10 is an enlarged perspective view showing the occurrence of cracks on the comb blade.

[Explanation of symbols]

1 tie bar cut die 2 die base 3 mounting screws 4 Tie bar cut punch 5 outer leads 6 Dam Bar 7 Dumb bar cut pieces 8 Positioning pin 9 tie bar cut 10 resin 11 tie bar cut die 12 cracks

Claims (2)

[Claims] 1. A tie bar cutting die having a comb blade for cutting a dam bar formed by wire cutting on a thin plate of ultrafine particle super hard material used as a material, and a comb blade of the tie bar cutting die for a hardened steel block used as a material. A tie bar cut die that is configured by processing the comb blade by wire cutting to be slightly smaller than the above, and fixing it to the die base that has an inlay for positioning the tie bar cut die so that the comb blades are in close contact with each other with a mounting screw. . 2. The tie bar cut die according to claim 1, wherein the die base has a positioning pin instead of the inlay.