JP2552097B2 - Metal member cutting die - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal member cutting die for cutting a metal member such as a tie bar protruding from an outer casing of an electronic device such as a semiconductor device.

[0002]

2. Description of the Related Art Generally, in a process of assembling a resin-sealed semiconductor device, a semiconductor chip mounted on a lead frame is resin-sealed, and then a large number of leads protruding from an outer shell formed by resin sealing are mounted. Cut the tie bar to connect,
It was necessary to separate the leads protruding from the outer shell. There was a metal member cutting die (hereinafter referred to as a tie bar cutting die) as equipment used in this step.

2A and 2B are a partial cutaway view and an AA arrow view showing an example of a conventional tie bar cutting die. As shown in FIG. 2, this tie bar cutting die has a plurality of cutting punches 11 that are embedded in an upper die 12 and extend downward.
And a cutting hole 1 opened corresponding to these cutting punches 11.
8 and a sub-post 16 which has a hole through which a cutting punch 11 slides and which extends downward from the upper mold 12.
By the repulsive force of the spring 16a
A pad 17 that holds the upper die 12 upright and a guide post 15 that stands on the lower die 13 and slides on the guide bush 15a to guide the up-and-down movement of the upper die 12.

When cutting a tie bar of a semiconductor device with this tie bar cutting die, first, the resin outer shell 19 is attached to the die 1.
Place in the recess of No. 4 and place. Next, press the upper mold 1
Lower 2 As a result, the pad 17 presses the lead 20 protruding from the resin outer shell 19 by the repulsive force of the spring 16a, and further, as the upper die 12 descends, the cutting punch 11 projects from the surface of the pad 17 and punches the tie bar 21. Along with it, it is inserted into the cutting hole 18. Then, the cut pieces of the tie bar that have been punched out are dropped below the cutting holes 18.

[0005]

In the above-mentioned conventional tie bar cutting die, the clearance between the cutting punch and the cutting hole is narrow so that the cutting surface of the lead portion after punching the tie bar has a small burr and a smooth cutting surface. For example, although it depends on the width of the tie bar, the clearance must be about 2 to 3 μm. However, on the other hand, in order to make the vertical movement of the upper mold smooth, the gap between the guide post and the guide bush needs to be at least about 4 μm.

For this reason, the clearance between the cutting punch and the cutting hole fluctuates each time the upper die is lowered, and the cutting punch often deviates from the cutting hole to cause a large flash on the cutting surface. It may hit the edge of the cutting hole and damage the blade surface. As a result, not only the product yield is lowered, but also the life of the mold is shortened.

Therefore, it is an object of the present invention to provide a smooth cut surface to be punched even if the sliding mechanism for opening and closing the die has rattling and without damaging the punch and die blade surfaces. An object of the present invention is to provide a metal member cutting die having a long life.

[0008]

The feature of the present invention is that the upper die and the lower die are clamped and opened by at least two guide posts and the upper die cutting punch is fitted in the lower die cutting hole. In a metal member cutting die for cutting a metal member protruding from an outer body of an electronic device, at least two guide pins embedded in the upper mold and extending downward,
A punch holder which has a guide hole guided by the guide pin and can move up and down, and in which a plurality of the cutting punches are embedded side by side, and at least two which are fixed to the punch holder outside the region where the cutting punches are embedded and extend downward. Book taper pin, a first spring member interposed between the punch holder and the upper die to apply a repulsive force to the punch holder, and a sub-post extending downward from the punch holder, which can move up and down and the cutting punch. A pad having a hole through which the pad slides, a second spring member sandwiched between the pad and the punch holder to apply a repulsive force to the pad, and a taper hole into which the cutting hole and the taper pin are fitted. And a die attached to the lower die, the metal member cutting die.

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a partial cutaway view showing an embodiment of a tie bar cutting die of the present invention when the die is opened and when the die is clamped. As shown in FIG. 1, this tie bar cutting die has two guide pins 5 which are embedded in the upper die 12a and extend downward, and guide holes which are guided by the guide pins 5. The punch holder 2 in which the cutting punches 11 are embedded side by side, the two taper pins 1 fixed to the punch holder 2 outside the region in which the cutting punch 11 is embedded and extending downward, are interposed between the punch holder 2 and the upper die 12a. The spring 4 inserted into the guide pin 5, a pad 17a fitted to a sub-post 16 extending downward from the punch holder 2 and capable of moving up and down, and having a hole through which the cutting punch 11 slides, the pad 17a and the punch holder 2
And a die 14a which has a tapered hole 3 into which the cutting hole 18 and the taper pin 1 are fitted and which is attached to the lower mold 13a.

Here, the cutting punch 11 of the punch holder 2
The positional accuracy between the taper pin 1 and the taper pin 1 is manufactured within an error range of, for example, 2 μm or less. Further, the positional accuracy of the cut hole 18 of the die 14a and the tapered hole 3 is also manufactured with the same accuracy. Further, the die 14a is fixed to the lower die 13a by the conventional dowel pin, but in the case of the present invention, it is better to eliminate the dowel pin and fix it simply by screwing. This is because the self-centering action of the taper pin 1 can be effectively exerted.

Next, the operation of this tie bar cutting die will be described. First, the resin outer shell 19 of the electronic device is placed on the die 14a of the lower mold 13a. Next, when the upper die 12a is lowered, the pad 17a first comes into contact with the lead portion, and the spring 16a contracts with the lowering, and the repulsive force causes the pad 17a to press the lead. Are combined.

At this time, if the position of the die 14a is misaligned, the die 14a is forcibly corrected in position by the lateral force generated by the engagement of the taper pin 1 and the taper hole 3 and cut with the cutting punch 11. The positions of the holes 18 coincide with each other. Further, the contraction cutting punch 11 of the spring 16a is projected from the lower surface of the pad 17a by the lowering of the upper mold 12a and is inserted into the cutting hole 18. As a result, the tie bar is cut into tie bar pieces 6 and dropped.

The length of the taper pin 1 is the pad 17
It is assumed that the taper pin 1 fits into the taper hole 3 when a contacts the lead, and the cutting punch 11 has a length such that when the taper pin 1 fits into the taper hole, the blade surface at the tip is a predetermined distance from the lower surface of the pad 17a. It is desirable to set the length so that it can be retracted. The amount of pulling of the cutting punch 11 determines the cutting force of the cutting punch 11. That is,
The contraction amount of the spring 4 is determined by this retracted amount, and the cutting force due to the repulsive force of the spring 4 is set. .
Therefore, when designing the spring 4, it is important to consider the amount of pull-in and design so as to obtain the necessary cutting force.

[0015]

As described above, according to the present invention, the guide pin is provided directly on the punch holder in which the cutting punch is embedded and the die having the cutting hole by providing the taper pin for aligning the cutting punch and the cutting hole with each other and the tapered hole. Even if rattling occurs in the linear guide mechanism formed by the post and the guide bush, the cutting punch and the cutting hole can be automatically aligned with each other by the self-aligning action that acts when the taper pin and the taper hole are engaged. As a result, the occurrence of burrs after punching was eliminated and the galling of the cutting punch with respect to the cutting holes was eliminated, and as a result, the product yield was improved and the life of the mold was extended.

[Brief description of drawings]

FIG. 1 is a partial cutaway view showing an embodiment of a tie bar cutting die of the present invention when the die is opened and when the die is clamped.

FIG. 2 is a partially cutaway view and an AA arrow view showing an example of a conventional tie bar cutting die.

[Explanation of symbols]

 1 Taper Pin 2 Punch Holder 3 Tapered Hole 4, 16a Spring 5 Guide Pin 6 Tie Bar Piece 11 Cutting Punch 12, 12a Upper Mold 13, 13a Lower Mold 14, 14a Die 15 Guide Post 15a Guide Bushing 16 Sub Post 17, 17a Pad 18 Cutting Hole 19 Resin outer body 20 Lead 21 Tie bar

Claims (1)

(57) [Claims] 1. A mold is clamped and opened between the upper mold and the lower mold by being guided by at least two guide posts, and a cutting punch of the upper mold is fitted in a cutting hole of the lower mold so as to protrude from an outer body of an electronic device. In a metal member cutting die for cutting a metal member, there are at least two guide pins embedded in the upper mold and extending downward, and guide holes guided by the guide pins, which can move up and down and a plurality of the cutting punches. Punch holders that are embedded side by side, at least two taper pins that are fixed to the punch holder outside the region where the cutting punch is embedded and extend downward, and a repulsive force that is interposed between the punch holder and the upper die and that is applied to the punch holder. And a first spring member that gives a force and a sub-post extending downward from the punch holder to move up and down and the cutting punch slides. A pad having a hole; a second spring member sandwiched between the pad and the punch holder to apply a repulsive force to the pad; a taper hole into which the cutting hole and the taper pin are fitted; A metal member cutting die, comprising a die attached to a lower die.