JPH08279581A - Correcting structure of width side warp in press die for lead frame - Google Patents

Abstract

PURPOSE: To simplify the adjustment work of a press die and to promote the miniaturization of a device by providing an adjusting cam with tapered surfaces slanted to both directions for supporting a correcting block on move side to move it in the directions of width and the up and down. CONSTITUTION: In correcting downward warp of a lead frame, a bi-directional tapered cam (an adjusting cam) 8 is moved in the direction of width, when a cam adjusting bolt is turned counterclockwise. A lower correcting block 5 is moved horizontally in a state being centered at the central part of the bi-directional tapered cam 8 and the right side of the lower correcting block 5 touches the inner wall of a die holder 2. When the cam adjusting bolt 13 is turned further, the tapered surface of the lower correcting block 5 is moved vertically being guided by the tapered surface of the bi-directional tapered cam 8. At the point the upper surface of the lower correcting block 5 protrudes from the upper surface of the die holder 2, the lead frame is warped in the direction of upward warp by the interaction with an upper correcting block 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame press die for correcting a warp or a warp in a width direction generated in a lead frame punching process for producing a lead frame in a lead die press die. Regarding the warp correction structure.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor package manufacturing process, after mounting a semiconductor chip on a lead frame,
A semiconductor package product is manufactured through a step of resin-molding this, and then subjecting the lead frame to individual processing and outer lead bending processing.

In the manufacturing process of the lead frame,
Larger packages due to the increase in the number of pins in recent years, miniaturization of the leads of the lead frame, the width of the lead frame itself is large,
In addition, technological innovation is becoming more intense due to thinner plates. For this reason, there is residual stress due to rolling and side cutting until the lead frame is delivered to the manufacturing process, and a slight warp in the width direction remains. Further, residual stress is added during punching of the lead frame, and after leaving the die for punching the lead frame, it often appears as warp or warp on the lead frame.

Therefore, conventionally, in order to correct the warp distortion according to the upward warp and downward warp of the lead frame, the stripper plate (upper mold) and the die holder (lower mold) forming the press die for manufacturing the lead frame are Each had a warp correction process.

Specifically, in the case of a warped lead frame, the correction is performed in a predetermined process in the stripper plate and the die holder. For example, a fixed correction piece having a flat surface is used on the stripper plate side, and a movable correction piece having an uneven surface is used on the die holder side. Then, the warp lead frame is pressed by the upper and lower correction pieces to give warp distortion in the direction opposite to the warp, and the lead frame is corrected to a flat state. Also,
In the case of a warped lead frame, a fixed correction piece having an uneven surface is used on the stripper plate side, and a movable correction piece having a flat surface is used on the die holder side. Then, the warp lead frame is pressed by the upper and lower correction pieces to give warp distortion in the direction opposite to the warp, and the lead frame is corrected to a flat state. Also,
The pinching part on the lead frame is either a section bar between individual ICs or a dam bar between external leads, both of which are pinched by parts outside the product to correct vertical warpage. It was

[0006]

However, there are the following problems in the width warp correction structure in the conventional lead frame press die. That is, in a die for punching a lead frame, a difference in warp correction effect occurs due to a difference in material supply state. For example, since the current reel has a warp after punching, the press die is used to correct the warp. However, the warp of the lead frame after punching may be corrected by replacing the reel with the next reel after the reel is finished. At this time, the pressing force of the press die may be too strong, and a warp may be newly added, and a heavy die has to be put down and put down just for this adjustment, resulting in a decrease in work efficiency. . Further, as another method, in order to eliminate loading and unloading of the mold, two steps of vertical warp correction process are required, so that the length of the press mold becomes long and the press device becomes large. Further, since the number of parts of the mold is increased, the cost of the mold is increased and the running cost is increased.

An object of the present invention is to solve the above-mentioned problems of the prior art and to perform the vertical warp adjustment work of the lead frame while the lead frame press die is placed, thereby simplifying the die adjustment work. The purpose of the present invention is to provide a width warp correction structure for a lead frame press die that has realized a reduction in running cost by promoting downsizing of the device.

[0008]

In order to solve the above problems, the present invention has the following constitution. That is, in the width warp correction structure in the lead frame press die for correcting the warp or warp in the width direction of the lead frame in the press die, at least one of the lead frames that can be fixed by sandwiching the lead frame from the vertical direction is A movable press die, and an upper / lower correction piece that can come into contact with the upper surface and the lower surface of the lead frame sandwiched and fixed to the press die, respectively, and either one of the upper / lower correction pieces is attached to the lead frame. A warp correcting means provided so as to be movable in the width direction, and an adjusting cam having a bidirectionally inclined taper surface for supporting a moving correction piece of the warp correcting means and moving the correction piece in the width direction and the vertical direction. And are provided.

[0009]

Operation: The lead frame is placed on the die holder, which is the lower die, and the stripper plate, which is the upper die, is lowered to sandwich the lead frame between the stripper plate and the die holder. Then, for example, the lower correction piece as warp correction means provided on the die holder side is moved in the width direction of the lead frame while being supported by the adjustment cam that is moved by rotating the adjustment bolt. At this time,
First, the lower correction piece is moved horizontally while being supported by the adjustment cam, and then moved upward along one of the bidirectionally inclined taper surfaces of the adjustment cam. Then, the contact surface of the lower correction piece is projected from the upper surface of the die holder, and the lead frame is sandwiched between the contact surface of the upper correction piece as the warp correction means fixed to the stripper plate side. Due to the uneven shape of the contact surfaces of the upper and lower correction pieces, the lead frame can be fixed on the mold in a flat state in which the warp distortion is corrected by warping the lead frame in the opposite direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing a width warp correction structure in a lead frame press die, FIG. 2 is an explanatory view of parts constituting the width warp correction structure, and FIG. 3 is an explanatory view showing a lead frame warp / down warp correction process. FIG. 4 is an explanatory diagram showing the relative positions of the upper and lower correction pieces and the acting position on the lead frame when correcting the warp.

First, a schematic structure of a width warp correction structure in a lead frame press die will be described with reference to FIGS. 1 and 2. In FIG. 1, 1 is a stripper plate which is a part of an upper die of a press die, and 2 is a die holder which is a lower die of the press die. The lead frame 3 (see FIG. 2) is punched into the shape of the lead frame through many steps on the progressive die and comes to the main correction step. The lead frame 3 is placed on the die holder 2, and the stripper plate 1 is lowered to clamp and fix the lead frame 3.

Reference numerals 4 and 5 are upper and lower correction pieces as warp correction means. The upper correction piece 4 is fixed to the stripper plate 1, and the lower correction piece 5 is provided in a recess 7 facing the punch guide of the die holder 2 so as to be slightly movable in the width direction (left and right direction in FIG. 1). ing. In this embodiment, the upper correction piece 4 is fixed and the lower correction piece 5 is movable, but the upper correction piece 4 may be movable and the lower correction piece 5 may be fixed. However, it is not preferable to make both the upper and lower correction pieces 4 and 5 movable because adjustment is difficult.

Reference numeral 8 denotes a bidirectional taper cam as an adjusting cam, which is brought into contact with the bottom portion of the moving lower correction piece 5 to move the lower correction piece 5 in the width direction and the vertical direction as shown in FIG. Has tapered surfaces 8a and 8b that are inclined in both directions. Reference numeral 9 denotes a correction piece pulling down bolt, which is a washer 10a on the bolt head 9a side and a washer 10b provided on the lower surface side of a flange portion 7a formed in the recess 7.
A correction piece lowering spring 11 is fitted between and. The tip of the correction piece pulling down bolt 9 is inserted into the bidirectional taper cam 8 and screwed into the lower correction piece 5. Further, the correction piece pulling down bolt 9 is in contact with the correction piece centering springs 12 provided inside the bidirectional taper cam 8 on both sides. The bidirectional taper cam 8 and the correction piece lowering bolt 9 are
The die holder 2 is provided so as to be movable in the width direction and the vertical direction in a space continuous with the recess 7.

The correction piece pulling-down spring 11 and the correction piece centering spring 12 are in a state in which the lower correction piece 5 shown in FIG. Each of them is arranged so as to have a natural length. Further, in this state, the lower correction piece 5 does not project above the upper surface of the die holder 2 (the supporting surface of the lead frame 3). The correction piece centering spring 12 defines that the lower correction piece 5 is positioned with the central portion in the width direction inside the recess 7 as the home position. The correction piece lowering bolt 9, the washers 10a and 10b, and the correction piece lowering spring 11 move together with the lower correction piece 5 in the width direction and move a little along the flange portion 7a. Also,
The correction piece centering spring 12 in the bidirectional taper cam 8 expands and contracts as the correction piece lowering bolt 9 moves.

Reference numeral 13 denotes a cam adjusting bolt, which is fitted into the holder from the side surface of the die holder 2 and has a tip portion screwed into the bidirectional taper cam 8. The bidirectional taper cam 8 is configured to move in the width direction by rotating the cam adjusting bolt 13. 14
Is a fixing bolt, and when the fixing bolt 14 is tightened, the tip end portion thereof is the cam adjusting bolt 13
Abut on and fix in the vertical direction.

Also, as shown in FIG. 2, the upper correction piece 4 is
(See FIG. 4) and the lower correction piece 5 are formed with projections 4a, 5a, flat portions 4b, 5b, and recesses 4c, 5c on the contact surface side with the lead frame 3 at a predetermined pitch. On the contact surface side of the correction piece 5 with the bidirectional taper cam 8,
Tapered surfaces 5d and 5e corresponding to the tapered surfaces 8a and 8b
Are formed respectively. The bidirectional taper cam 8 and the lower correction piece 5 are provided with a correction piece lowering bolt 9
An elongated hole 8c and a screw hole 5f through which the is inserted or fitted are drilled.

The protrusions 4a, 5a and the flat portions 4b, 5
b, the recesses 4c and 5c are formed with a pitch interval (a pitch interval between leads due to the leads) that does not contact the lead frame 3 on the extension line of the outer lead 3a. It is arranged so as to contact the dam bar 3b, more preferably the section bar (see FIG. 4), by way of example, in the widthwise portion that does not remain. Further, the lower correction piece 5 is configured to be movable in the recess 7 by one pitch of the outer lead 3a according to the movement of the bidirectional taper cam 8 in the width direction. The side rails 3c of the lead frame 3 are provided with guide holes 3d used for fixing on the mold and for pitch feed of the lead frame 3.

Next, an operation of correcting the warp of the lead frame 3 clamped by the stripper plate 1 and the die holder 2 will be described with reference to FIGS. 3 and 4. In FIG. 4A, the positions where the protrusions 4a and 5a of the upper and lower correction pieces 4 and 5 come into contact with the lead frame 3 when the width warp (upward warp / downward warp) is corrected are shown by hatched lines. As described above, the protrusions 4a and 5a contact the lead frame 3 at positions not on the extension lines of the outer leads 3a, for example, as shown in FIG. 4A, the pitch of the outer leads 3a in the width direction. It is configured to be moved by a distance and abut on the shaded portion.

To correct the warp of the lead frame 3, as shown in FIG. 3A, the fixing bolt 14 on the die holder 2 side is retracted upward to release the fixed state, and then the cam is released. When the adjusting bolt 13 is rotated counterclockwise, the bidirectional taper cam 8 moves in the width direction from the position shown in FIG. 1 (home position) in the direction indicated by the arrow A (rightward in the figure). At this time, the lower correction piece 5 moves horizontally in the direction of arrow A while being centered on the center of the bidirectional taper cam 8, and the right side surface of the lower correction piece 5 abuts the inner wall 2a of the die holder 2. The lower correction piece 5 is pressed against the inner wall 2a by the pressing force of the correction piece lowering spring 11 and the correction piece centering spring 12. The lower correction piece 5, the correction piece lowering bolt 9, the washer 10a, and the correction piece lowering spring 11 are integrated with each other to move the washer 10b along the flange portion 7a.

Then, when the cam adjusting bolt 13 is further rotated, the taper surface 5e of the lower correction piece 5 is guided by the taper surface 8b of the bidirectional taper cam 8 and is vertically moved in the direction indicated by the arrow B (upper part of the drawing). Direction). Then, when the upper surface of the lower correction piece 5 projects from the upper surface of the die holder 2, the lead frame 3 is interacted with the upper correction piece 4 by interaction.
A warp distortion (hit form) in the upward warp direction is given to.

Specifically, as shown in FIG. 4 (b), the lower correction piece 5 moves in the width direction below the outer lead of the section bar so that the protrusion 5a of the lower correction piece 5 moves upward. The flat bar portion 4b of the correction piece 4 holds the dam bar 3b from the vertical direction at the position where the concave portion 5c and the protruding portion 4a face each other. When the cam adjusting bolt 13 is rotated by a predetermined amount, the screwing position is fixed by tightening the fixing bolt 14. As a result, since the lead frame 3 is held in an upward warp on the mold, the downward warp can be corrected, and the lead frame 3 can be corrected into a flat state as a whole.

When correcting the warp of the lead frame 3, as shown in FIG. 3B, the fixing bolt 14 on the die holder 2 side is retracted upward to release the fixed state, and then the cam is released. When the adjusting bolt 13 is rotated to the right, the bidirectional taper cam 8 moves in the width direction in the direction indicated by the arrow C (leftward in the drawing). When moving from the state shown in FIG. 3A, the taper surface 5e of the lower correction piece 5 is guided by the taper surface 8b of the bidirectional taper cam 8 to descend to the centering state. Then, when the cam adjusting bolt 13 is rotated, the cam adjusting bolt 13 is horizontally moved in the direction of the arrow C while being centered on the center of the bidirectional taper cam 8, and the left side surface of the lower correction piece 5 abuts on the inner wall 2b of the die holder 2. . The lower correction piece 5 is a spring 1 for lowering the correction piece.
1 and the correction piece centering spring 12 is pressed against the inner wall 2b. The lower correction piece 5, the correction piece lowering bolt 9, the washer 10a, and the correction piece lowering spring 11 are integrated with each other to move the washer 10b along the flange portion 7a.

Then, when the cam adjusting bolt 13 is further rotated clockwise, the taper surface 5d of the lower correction piece 5 is guided by the taper surface 8a of the bidirectional taper cam 8 and is vertically moved in the direction indicated by the arrow B (in the figure). Move upward). And
When the upper surface of the lower correction piece 5 projects from the upper surface of the die holder 2, the warp distortion (hit form) in the downward warp direction is given to the lead frame 3 by the interaction with the upper correction piece 4.

Specifically, as shown in FIG. 4 (c), the lower correction piece 5 moves in the width direction below the dam bar 3b,
Compared to (b), the outer lead 3a is moved by one pitch, and the protrusion 5a of the lower correction piece 5 is recessed 4c of the upper correction piece 4.
In addition, the flat bar portion 5b causes the protruding portion 4a to sandwich the dam bar 3b from above and below at a position facing each other. As a result, since the lead frame 3 is held in the downward warp on the die, the upward warp can be corrected and the overall flat state can be corrected.

According to the above construction, both camber and camber of the lead frame 3 can be corrected by one cam adjusting bolt 13, so that even if the camber changes from top to bottom by the adjustment up to the previous stroke, The warp correction process is facilitated without lowering the mold, and the processing accuracy can be maintained with high accuracy. The size of the mold can be reduced because only one correction process is required, and the running cost can be further reduced when the mold having the warp correction structure according to the present invention is set in a press machine having one rank smaller.

Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and many modifications can be made without departing from the spirit of the invention. Is.

[0027]

As described above, according to the present invention, one cam adjusting bolt can correct both the upward warp and the downward warp of the lead frame in the width direction. Upward and downward warpage adjustment work can be facilitated, the adjustment work time can be shortened, and the processing accuracy can be maintained with high accuracy. Also,
Since two strokes are not required for both the upper die and the lower die, the number of parts of the die can be reduced, and the length of the press die can be reduced by one stroke, so the die cost becomes cheaper and the running cost is reduced. Achieving a drop. Alternatively, if the main mold is set on a press machine that is one rank smaller, the running cost will be further reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a width warp correction structure in a lead frame press die.

FIG. 2 is an explanatory view of parts constituting a width warp correction structure.

FIG. 3 is an explanatory diagram showing an upward warp / downward warp correction process of the lead frame.

FIG. 4 is an explanatory diagram showing the relative positions of the upper and lower correction pieces and the acting position on the lead frame when correcting the warp.

[Explanation of symbols]

 1-Striper plate 2-Die holder 3-Lead frame 3a-Outer lead 3b-Dam bar 3c-Side rail 3d-Guide hole 4,5-Up / down correction piece 4a, 5a-Projection 4b, 5b-Flat part 4c, 5c-Recesses 5d, 5e, 8a, 8b-Tapered surface 5f-Screw hole 7-Recess 7a-Flange 8-Adjustment cam 8c-Elongated hole 9-Correcting piece lowering bolt 9a-Bolt head 10-Washer 11-Modification Spring for pulling down pieces 12 -Spring for correcting piece centering 13 -Cam adjusting bolt 14 -Fixing bolt

Claims (4)

[Claims] 1. A width warp correction structure for a lead frame press die for correcting the warp or warp in the width direction of a lead frame in a press die, wherein the lead frame can be clamped and fixed in the vertical direction. A press die; and upper and lower correction pieces that can come into contact with the upper surface and the lower surface of the lead frame sandwiched and fixed in the press die, respectively.
Warp correction means equipped with one of the lower correction pieces so as to be movable in the width direction of the lead frame, and both of the warp correction means for supporting the movement side correction piece and moving it in the width direction and the vertical direction. A width warp correction structure in a lead frame press die, comprising: an adjusting cam having a tapered surface inclined in a direction. 2. The width warp correction in the lead frame press die according to claim 1, wherein the warp correction means is a dam bar or a section bar of the lead frame and abuts on the lead frame except when the outer lead is extended. Construction. 3. The upper and lower correction pieces have protrusions, flat portions, and recesses formed at a predetermined pitch on the contact surface side with the lead frame, respectively, and contact the adjustment cam of the correction piece on the moving side. 3. The warp correction structure for a lead frame press die according to claim 1, wherein a taper surface corresponding to the adjusting cam is formed on the contact surface. 4. The adjusting cam is moved in the width direction by rotating a cam adjusting bolt, and the correction piece on the moving side is movable by one pitch of the outer lead. A warp correction structure for a lead frame press die according to claim 2 or 3.