JPH0851176A - Die and punch guide used for press die for manufacturing lead frame and manufacture - Google Patents

Abstract

PURPOSE:To manufacture dies used for producing lead frames having extremely narrow pitches and punch guides easily. CONSTITUTION:A central piece hole 16 using a place crossing a cavity or a guide hole as a drawing line as a section in which a lead frame material is drawn off at the time of the molding of an inner lead on the side in front of the front end of the inner lead, is formed to the base material 10 of a die while the cavity 18 is formed by communication with the drawing line of the central piece hole 16. A central piece 20, which has a shape fitted into the central piece hole 16 and in which a groove section forming the front end section of the cavity 18 on the side in front of the place crossing the cavity 18 is formed on an external surface, is shaped apart from the base material 10, and the central piece 20 is fitted and supported to the central piece hole 16, thus manufacturing the die with the required cavity 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die and a punch guide manufacturing method used for a lead frame manufacturing press die.

[0002]

2. Description of the Related Art When a lead frame is manufactured by a press punching process, a lead frame material having a predetermined lead shape is obtained by pressing the lead frame material with a press die while sequentially feeding the lead frame material. The die used in this punching is provided with punched holes in the order of punching, and punches are manufactured in accordance with the punched holes. Further, since the punch is extremely thin, a punch guide that guides the side surface of the punch is used during punching. By the way, the lead frame press punching is required to be extremely fine and highly accurate, and therefore the die used therefor is also required to have extremely high precision. Conventionally, split dies were often used in dies for manufacturing lead frames, but extremely high precision was required for die manufacturing, and microfabrication was required in recent years. Is increasing.

[0003]

FIG. 6 schematically shows a method of forming a hole in a die by wire electric discharge machining. As shown in the figure, in wire electric discharge machining, first, a prepared hole 6 is formed in accordance with the hole 5 to be formed, and a wire is passed through the prepared hole 6 for machining. As shown in Fig. 6 (b), the pilot hole 6 must be provided within the range of the punched hole 5 which is a portion to be removed when the die is manufactured, but the lead frame has many pins and the lead interval becomes narrow. Then, it becomes difficult to provide the pilot hole 6 in such a narrow range.

For example, some of recent lead frames have a punch punching width of only 0.45 mm, and the punching width of a lead hole is 0.4.
Since the diameter of about mm is the minimum diameter on a practical level, it becomes extremely difficult to secure the positional accuracy of drilling and the verticality. In addition, a small hole such as 0.4 mm diameter has a diameter of 0.
The work of passing a wire as thin as 05 mm is also difficult. As described above, as the density of the lead frame becomes higher, it becomes difficult to manufacture a die that requires fine processing, which causes a problem that the work efficiency of the die manufacturing is lowered.

The above-mentioned circumstances also apply to the manufacture of punch guides. That is, the punch guide is provided with a guide hole having the same shape as the punch hole provided in the die for guiding through the punch. Since this guide hole must be formed extremely finely like the punched hole of the die, wire electric discharge machining has come to be used also in the production of the punch guide like the die.

The present invention relates to a die and a punch guide used for producing a lead frame in which inner leads and the like are formed with extremely high density when producing a die and a punch guide for a press die used for producing these lead frames.
An object of the present invention is to provide a method of manufacturing a die and a punch guide, which makes it possible to manufacture a suitable die and a punch guide even when the manufacturing is difficult by a normal wire electric discharge machining.

[0007]

The present invention has the following constitution in order to achieve the above object. That is, in a method of manufacturing a die having a punch hole for punching a lead and a punch guide having a guide hole for guiding a punch, an inner lead is provided on a base material of the die or the punch guide before a tip of the inner lead. Is a portion where the lead frame material is pulled out at the time of molding, and a hollow frame hole is provided as a blank line at a position crossing the blank hole or the guide hole, and the blank hole is communicated with the blank line of the hollow frame hole or A guide hole is provided and, apart from the base material, a groove portion that is shaped to fit into the inner hole and that forms the tip of the hole or guide hole that is ahead of the position where the hole or guide hole is crossed. Providing the inner ring formed on the outer surface,
It is characterized in that a die having a required punched hole or a punch guide having a guide hole is formed by fitting and supporting the hollow core in the hollow hole. In addition, a pilot hole for wire electric discharge machining is formed in the inner area of the base material where a hollow hole is formed, and a wire is passed through the pilot hole to form the hollow line of the hollow core hole and the blank line of the hollow hole or the guide hole. By performing a series of wire electric discharge machining for and, efficient machining becomes possible. Further, the punching line position of the inner top hole is set in the gap between the outer peripheral edge of the die pad and the tip of the inner lead, and the punching line position of the inner top hole of the support bar supporting the die pad. It is characterized in that the punch side surface is set in the vicinity of a boundary position where the punch side surface is curved from a straight line to a curved line at the tip end portion on the die pad side at the punch position for forming the side surface.

[0008]

[Function] When manufacturing the die or punch guide of the press die used for manufacturing the lead frame, the cutting line position is set on the tip side of the inner lead to be pulled out when molding the inner lead, and the base material is set. By forming a hollow hole in the core, a punch hole or a guide hole is formed using the hollow hole, and by inserting a separately manufactured hollow core into the hollow hole, a die having a required hollow hole or guide hole is formed. Or get a punch guide. The center hole is provided so that the punched line of the hole or guide hole passes through the hole of the hole, and the hole or guide hole is efficiently processed by using the hole during wire electrical discharge machining. enable. By providing the prepared hole inside the inner top hole, the prepared hole can be easily processed, and the inner top hole can be used as a common prepared hole to easily form the punched hole or the guide hole.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory view showing an embodiment in which a die is manufactured by the method of the present invention. FIG. 1A shows a step of first forming a prepared hole 12 for passing a wire for wire electric discharge machining in a die substrate 10 formed in a predetermined block shape. Here, the position where the prepared hole 12 is formed is substantially the center position of the lead frame to be formed, and the hole diameter is set to a size that allows a wire for electric discharge machining to be easily passed through, for example, about 3 mm diameter. The portion in which the prepared hole 12 is provided is a portion to be removed from the die base material 10 in a later step, and therefore the arrangement position and the hole diameter may be appropriately set under the condition that does not affect the die manufacturing. It is preferable to make the prepared hole 12 large in this way, because the wire threading work can be facilitated and the work efficiency can be improved.

After the prepared hole 12 is provided, the wire 14 is passed through the prepared hole 12 to start the electric discharge machining as shown in FIG. 1 (b).
FIG. 1C shows a state where electric discharge machining is started from the prepared hole 12. In wire electric discharge machining, first, as shown in FIG. 1 (c), a central portion is punched out into a rectangular shape to form a hollow top hole 16. In FIG. 4, the positions of the blank lines when forming the inner comb hole 16 are shown by broken lines. A typical lead frame has a die pad 30 in the center.
Is located and surrounds the die pad 30, and inner leads 32 are arranged around the die pad 30. The operation of providing the inner hole 16 is an operation of setting a punching line position in the void portion between the die pad 30 and the tips of the inner leads 32 and pulling it out. The space between the die pad 30 and the tips of the inner leads 32 is a portion where the lead frame material is pulled out when the inner leads 32 are molded.

After forming the inner hollow hole 16 in the central portion of the die base material 10, the process proceeds to forming a hole for the lead portion according to the lead pattern to be formed. FIG. 1 (d) shows a state in which the hole 18 in the lead portion is processed. In the processing of the punched holes 18, the inner top hole 16 is used as a common prepared hole, and the punched holes 18 are formed by a series of workings. As shown in FIG. 4, the boundary line of the inner hole 16 crosses the punched holes 18, so that each punched hole 18 can be formed by a continuous process.

By thus forming the common top hole 16 as a common pilot hole, it is not necessary to provide a pilot hole for forming each punched hole or pass a wire through the pilot hole as in the conventional case. It is possible to greatly improve work efficiency.
Further, since the inner top hole 16 is a common hole, it is possible to perform the machining of each of the punched holes 18 by continuous machining by automatic operation, and the machining of the die can be made efficient.

FIG. 2 shows a state after machining the inner hole 16 and the lead hole 18 in the die base material 10 by the above-described wire electric discharge machining. As a processing die, a separately formed inner core is fitted into the inner core hole 16 to finally form a processing die. In FIG. 2, reference numeral 20 designates a hollow insert fitted in the hollow insert hole 16. The inner core 20 is formed so as to fit exactly into the inner core hole 16, and a groove portion 22 that forms the tip of the hole 18 is provided on the outer peripheral side surface thereof.

As shown in FIG. 4, the boundary line between the outer surface of the inner core 20 fitted in the inner core hole 16 and the die base material 10 is located at a position crossing the tip of the punched hole 16. Above middle 20
The groove portion 22 provided on the outer surface of the is for forming the tip portion of the hole 16. The inner ring 20 is manufactured and prepared separately from the die base material 10. Providing the groove 22 on the outer surface of the inner ring 20 can be easily performed by wire electric discharge machining or grinding. Figure 3 shows the inner top hole 16
The state where the inner core 20 is fitted into the die to form the processing die 40 is shown. The die 40 for this processing is the core 20 and the die base material 1.
By combining with 0, the predetermined punched hole 18 is formed.

As a method of fixing the inner core 20 to the die base material 10, a flange is provided on the lower surface of the inner core 20,
Insert the inner top 20 from the bottom of the inner top hole 16 and mount it.
A method for fixing the die 40 to the die frame to support the inner top 20, a method for fixing the inner top 20 fitted in the inner top hole 16 by screwing from the lower side of the die frame, and a middle top for the inner top 20 There are methods such as brazing to 16 and fixing.

In the case of manufacturing a lead frame using the above-described processing die 40, first, the inter-lead portion is press-pressed and then the outer peripheral portion of the die pad 30 and the inner lead 32 are formed as shown in FIG. The tip end of the inner lead 32 is formed while the die pad 30 is formed by removing the gap from the tip. In the die 40, since the punching line position of the inner core 20 is located in this removed portion, the influence of manufacturing the die 40 by combining the inner core 20 and the die base material 10 does not appear in the product.

The die pad 30 and the inner lead 3
Since the support bar 34 that supports the die pad 30 is left without being removed when the tip of the die 2 is formed, the punching position shift between the punch that forms the side surface of the support bar 34 and the punch that removes the outer shape of the die pad 30. If there is, this will appear in the product. That is, as shown in FIG. 5, the support bar 34 is formed by punching out the side surface thereof with the punching punch 19a and then by punching out the outer shape of the die pad 30 to form the connecting portion between the support bar 34 and the die pad 30 with the punching punch 19b. To do. In order to suppress the influence of these punch punching position shifts, as shown in FIG. 5, the die base material 10 and the center insert are placed near the boundary position where the punch side surface curves from a straight line to a curved line at the tip of the punching punch 19a. The boundary position of 20 is set, and the support bar 34 of the punch 19b to be punched out is set.
It is preferable that the aiming position of the side surface of the punch is a curved portion of the punch 19a. By doing so, it is possible to suppress the influence of the displacement of the punch when molding the support bar 30 portion.

In the progressive die, since the lead portion at a predetermined position is sequentially subjected to press punching for each working stage, the punching pattern for each working stage varies. The present method can be appropriately used according to such various punching patterns, and the entire progressive die can be formed by manufacturing each processing stage by a similar method. The die manufacturing method described above is particularly suitable for the punching process of the inner lead portion where the leads are formed with the highest density, and the conventional manufacturing method may be used for the portion having a wide lead interval such as the outer lead portion. .

As described in the embodiment, the method is not limited to the usual product in which the die pad is located in the central portion of the lead frame, and the die pad is offset to one side from the central position of the lead frame. Applicable to various products. Also in that case, set the punching line position of the inner top hole in the dropout part between the die pad and the tip of the inner lead,
The punched line may cross the punched hole for forming the inner lead. Further, the invention can be similarly applied to a product having no die pad. In this case, the punching line position of the inner top hole may be set so as to be inside the tip of the inner lead and across the punching hole for molding the inner lead. Further, the present method can be applied to various types of lead frames as well as quad type lead frames.

Further, although the inner top hole 16 is formed in a rectangular shape in the above embodiment, the shape of the inner top hole is not limited to a rectangular shape, and may be set to an appropriate shape according to the lead arrangement to be formed. For example, a rectangular corner portion may be cut obliquely, a rectangular corner portion may be cut into an L shape in a plan view, or the like.

Although the die used for the press die has been described above, the same can be applied to the case where a punch guide is manufactured similarly to the die. Even when making a punch guide, a guide hole with the same shape as the lead hole formed in the die is formed.In that case, as in the case of making the die above, a punch hole is formed in the base material of the punch guide. A punch guide can be constructed by forming a guide hole by electric discharge machining and fitting a separately manufactured inner core into the inner core hole. As with the die above, the guide holes formed in the punch guide require high-density lead frames and extremely fine processing, but this method of combining the top and the base material with the top holes is combined. According to this, it becomes possible to easily manufacture even a punch guide which has been very difficult to process by the conventional wire electric discharge machining.

[0022]

As described above, according to the method of manufacturing the die and the punch guide of the press die for manufacturing the lead frame of the present invention, the leads are formed at a very high density, which is difficult to manufacture by the conventional method. It is possible to easily manufacture the die and the punch guide used for manufacturing the lead frame. This enables the fabrication of dies and punch guides that can be used to fabricate leadframes with extremely narrow pitch leads that could not be produced by conventional methods. Further, when a die or punch guide is manufactured by wire electric discharge machining, by providing a prepared hole in the portion where the inner top hole is formed, machining can be performed easily and efficiently, which is a remarkable effect. Play.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method of manufacturing a die of a press die for manufacturing a lead frame.

FIG. 2 is an explanatory view showing a die base material having a hollow top hole and a hollow top attached to the die base material.

FIG. 3 is an explanatory diagram of a die in which a die base material and a filling piece are integrated.

FIG. 4 is an explanatory diagram showing a position of a hollow line in the inner top hole.

FIG. 5 is an explanatory view showing a punch position for forming a support bar and a punching line position of a center top hole.

FIG. 6 is an explanatory view showing a conventional method of manufacturing a die of a press die for manufacturing a lead frame.

[Explanation of symbols]

 10 Die Base Material 12 Prepared Hole 14 Wire 16 Inner Top Hole 18 Drilling Hole 19a Pre-punched Punch 19b Post-punched Punch 20 Inner Top 22 Groove 30 Die Pad 32 Inner Lead 34 Support Bar 40 Die

Claims (4)

[Claims] 1. A method of manufacturing a die having a punch hole for punching a lead and a punch guide having a guide hole for guiding a punch, wherein a base of the die or the punch guide is located farther than a tip of an inner lead. Is a portion where the lead frame material is pulled out during the molding of the inner lead, and a hollow top hole is provided as a blank line at a position that crosses the blank hole or the guide hole. A hole or guide hole is provided, and in addition to the base material, a tip portion of the hole or guide hole that is shaped to fit in the inner hole and is located ahead of the position crossing the hole or guide hole is formed. A die or a guide having a required hole is provided by providing an inner core having a groove portion formed on the outer surface thereof, and by fitting and supporting the inner core in the inner hole. Die and punch guide method fabrication used for the lead frame for manufacturing the press die, characterized in that to create a punch guide having a bore. 2. A base hole for wire electric discharge machining is formed in an inner area where a hollow body hole is formed in a base material, and a wire is passed through the base hole to form a hollow wire of the hollow core hole and the hollow hole or a guide hole. The method for producing a die and a punch guide used in a press die for manufacturing a lead frame according to claim 1, wherein the punching is performed by a series of wire electric discharge machining. 3. The lead frame manufacturing press die according to claim 1 or 2, wherein the punching line position of the inner top hole is set in the space between the outer peripheral edge of the die pad and the tips of the inner leads. Die and punch guide manufacturing method. 4. The punching line position of the inner top hole is set near the boundary position where the punch side surface is curved from a straight line to a curved line at the die pad side tip end at the punch position for molding the side surface of the support bar that supports the die pad. A method of manufacturing a die and a punch guide used in a press die for manufacturing a lead frame according to claim 1, 2, or 3.