JP2862941B2 - Dam bar cut punch and punch guide - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dam bar cut punch and a punch guide.

(Prior Art) Unnecessary portions are cut and removed after resin sealing of a dam bar of a lead frame. FIG. 7 shows the lead frame after resin sealing. 2 is a dam bar, 4 is a resin sealing portion, and 6 is a resin in the dam. The dam bar cut is for cutting and removing the dam bar 2 portion between the adjacent external leads 8 as shown in the figure.

Conventionally, this dam bar cut is performed by aligning a dam bar cut punch formed in a comb blade shape in accordance with the lead interval of the external lead with the dam bar and cutting off the dam bar at a time. At this time, a punch guide is used for the purpose of guiding the comb blade and for preventing the punch blade from sticking to the lead frame after cutting the dam bar.

Fig. 8 shows a conventional dam bar cut punch 10
And the punch guide 12. FIG. 9 is a view of the dam bar cut punch 10 and the punch guide 12 as viewed from the bottom side. The punch guide 12 is provided with guide holes 12a for guiding a comb-shaped punch blade 10a.

The left and right sides of the punch blade are cutting blade portions, and the punch blade and the guide hole 12a are machined with a clearance of about 10 μm. In addition, a guide plate 14 is provided by abutting the end face of the punch guide 12 to guide the dam bar cut punch in the width direction of the dam bar, and the gap between the outer side surface of the punch blade and the guide hole 12a is also processed with fine clearance. ing.

(Problems to be Solved by the Invention) Recently, the number of pins in a lead frame has been increased, and the lead interval is
Since it has been narrowed to about 0.5 mm, very fine processing is required for punch guides, and it is very difficult to process the dam bar cut punch and punch guide with the required clearance It is becoming.

As shown in FIG. 9, the conventional punch guide 12 has a guide hole.
The corner of the guide hole 12a is cut out in a V-shape. This is because the corner of the guide hole 12a cannot be machined accurately at a right angle, so that the corner is cut out to form a relief. When the lead interval is reduced, the adjacent guide holes 12a come into contact with each other, so that it is not possible to cut out the space in a V-shape. There is a problem that the strength of the guide itself is insufficient.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to easily cope with a multi-pin dam bar cut requiring more fine processing and to obtain a required accuracy. It is an object of the present invention to provide a dam bar cut punch and a punch guide used therefor.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, in a dam bar cut punch in which a comb-shaped punch blade is formed at the tip and each punch blade slides into a guide hole provided in a punch guide and is guided, both ends of a punch body of the dam bar cut punch The surface is provided with a guide portion that slides into a guide groove provided in the punch guide.

Further, in a punch guide provided with a guide hole through which a punch blade provided at the tip of a dam bar cut punch slides, the guide hole is formed with a fine clearance between the punch blade and the cutting blade, and the length of the punch blade is reduced. The dam bar cut punch is provided with a guide groove in which guide portions provided on both end surfaces of the dam bar cut punch slide. Further, the guide hole is provided in a long hole shape in the longitudinal direction of the punch blade with a precise clearance between the punch blade and the cutting blade, and a guide member for guiding an outer surface of the punch is provided.

(Operation) In the dam bar cut punch, the punch blade is guided by the guide hole of the punch guide, and cuts the dam bar between the punch blade and the cutting blade. The punch body is guided by sliding the guide portion of the dam bar cut punch into the guide groove provided in the punch guide, or by guiding the outer surface of the dam bar cut punch with a guide member, and the guide hole of the punch guide is elongated. Even if it is formed in a shape, accurate dam bar cutting can be performed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing one embodiment of a dam bar cut punch 20 according to the present invention. The dam bar cut punch 20 is formed in a thin plate shape slightly wider than the dam bar width, and a comb blade-shaped punch blade 22 is formed at a lower portion of the punch body.

Both end faces of the punch body 21 above the base position of the punch blade 22 are formed so as to slightly project outward as shown in the drawing.

The dam bar cut punch 20 performs a dam bar cut guided by a punch guide. Fig. 1 shows a punch guide
30 is shown by imaginary lines. 30a is a guide hole provided in the punch guide 30.

FIG. 2 is an enlarged plan view showing the punch guide 30. FIG. The punch guide 30 is provided with a guide hole 30a corresponding to each punch blade 22 position. The guide hole 30a is formed into an arc surface in which the inner wall surface on the back side is convex outward, and this rounded portion serves as a relief for the punch blade 22. Note that a fine clearance is provided between the guide hole 30a and the cutting blade of the punch blade 22.

By making the guide hole 30a longer than the punch blade 22 and rounding the inner side as described above, the adjacent guide hole
30a can be provided closer to each other, so that it is possible to easily cope with an increase in the number of pins, and there is an advantage that insufficient strength can be eliminated because the base of the guide portion does not become thin. Further, it is difficult to precisely process a rectangular hole by fine machining, but the above-mentioned round processing can be easily performed by ordinary processing.

At the time of dam bar cutting, the guide plate 32 is set on one end side of the punch guide 30 as shown in FIG. 2, but as a result of forming the guide hole 30a in a long hole shape as described above, There is a risk that the guide in the width direction of the punch blade 22 will not be complete with only the plate 32.

Therefore, in the present invention, the guide grooves 34a, 34b provided on both end surfaces of the punch body 21 of the dam bar cut punch 20 are provided in the punch guide 30 so that the projecting portions 24a, 24b also slide in, and the projecting portions 24a, 24b It guides the cut punch 20.

FIG. 3 is a plan view showing an embodiment of the punch guide 30, and FIG.
The figure is a sectional view. This embodiment is an example in which dam bar cutting is performed on a lead frame on which three resin sealing portions are formed. The punch guide 30 is provided with a guide hole 30a corresponding to a dam bar provided on a lead extending from both sides of each resin sealing portion.

The punch guide 30 is set on the lead frame as shown in FIG. 4, and a dam bar cut punch is set on each of the resin sealing portions to perform a dam bar cut.
Since the dam bar cut punch is guided by the guide groove 34a as described above, the positioning of the punch blade 22 can be accurately performed, and accurate dam bar cut and sticking of the punch blade to the lead frame can be prevented.

FIGS. 5 and 6 show an embodiment showing another guide method for guiding the dam bar cut punch 20 when using a punch guide having a long guide hole 30a.

In this embodiment, the inner surface of the dam bar cut punch 20 is guided by the end surface of the guide plate 32, and the outer surface of the dam bar cut punch 20 is guided by the end surface of the nest 40, which is a guide member fixed to the punch guide 30. It is characterized by.
The nest 40 is a member having a rectangular cross section formed separately from the punch guide 30 as shown in FIG. 6, and an upper inner wall portion of an insertion hole of the punch guide 30 into which the dam bar cut punch 20 is inserted. Is fixed to the stepped portion provided at Thus, the inner surface of the dam bar cut punch 20 is in sliding contact with the guide plate 32 and the outer surface thereof is in sliding contact with the nesting member 40, and positioning in the width direction is performed.

In the embodiment described above, the dam bar cut punch 20
Since only the overhang portions 24a and 24b guide the dam bar cut punch 20, the dam bar cut punch 20 is supported only on both side portions, and an intermediate space between the punch body 21 and the inner wall surface of the punch guide 30 is a gap. On the other hand, in the case of this embodiment,
Since the nest 40 is entirely in sliding contact with the outer side surface of the punch, the guide of the dam bar cut punch 20 can be more effectively performed. Also, when making the punch guide 30, it is difficult to make the corner of the insertion hole into which the dam bar cut punch 20 is inserted exactly at a right angle, but it is necessary to form the insert 40 separately from the punch guide 30 By increasing the accuracy of the nest 40, more accurate positioning can be performed.

In the punch guide of each of the above-described embodiments, the processing of the punch guide can be extremely facilitated by forming the guide hole in a long hole shape and simplifying the shape of the guide hole. Further, since the guide holes can be formed close to each other, it is possible to easily cope with dam bar cut of a multi-pin lead frame. Further, by guiding the dam bar cut punch by the punch guide, the guide of the punch blade can be accurately performed, and the processing can be performed with high accuracy.

As described above, the present invention has been described variously with reference to preferred embodiments. However, the present invention is not limited to the embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.

(Effects of the Invention) According to the present invention, the punch guide for guiding the dam bar cut punch can be extremely easily processed by the above-described configuration, and the guide hole provided in the punch guide has a multi-pin lead frame. , And can be formed at a higher density.

In addition, the dam bar cut punch can be accurately guided at the time of dam bar cut, and the dam bar cut can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a dam bar cut punch according to the present invention, FIG. 2 is an explanatory view showing an enlarged view of a punch guide according to the present invention, and FIG. 3 and FIG. 5 and 6 are plan and sectional views showing another embodiment of the punch guide. FIG. 7 is an explanatory view showing a dam bar cut portion of the lead frame.
FIG. 9 and FIG. 9 are explanatory views showing a conventional dam bar cut punch and a punch guide. 10, 20 …… Dumbar cut punch, 10a, 22 …… Punch blade, 21 …… Punch body, 12, 30 ……
Punch guides, 12a, 30a ... guide holes, 14, 32 ... guide plates, 24a, 24b ... overhangs, 34a, 34b ... guide grooves, 40 ... nesting.

Claims (3)

(57) [Claims] 1. A dam bar cut punch in which a comb-shaped punch blade is formed at the tip and each punch blade slides into a guide hole provided in a punch guide and is guided. A dam bar cut punch characterized in that guide portions are provided on both end surfaces of a main body so as to slide into guide grooves provided in a punch guide. 2. A punch guide provided with a guide hole into which a punch blade provided at the tip of a dam bar cut punch slides, wherein the guide hole is formed with a precise clearance between the punch blade and a cutting blade. A punch guide provided in a long hole shape in a longitudinal direction of the blade, and provided with guide grooves into which guide portions provided on both end surfaces of the dam bar cut punch slide. 3. A punch guide provided with a guide hole through which a punch blade provided at the tip of a dam bar cut punch slides, wherein the guide hole is formed with a fine clearance between the punch blade and the cutting blade. A punch guide provided in a long hole shape in a longitudinal direction of the blade, and a guide member for guiding an outer surface of the punch is provided.