JPS62123751A - Lead forming mold - Google Patents

Abstract

PURPOSE:To prevent plating on lead surfaces from being peeled or so, by forming recessed parts both on a forming surface of an either side of a molding material which bends leads and on a portion in contact with cutting margins from which tie bars are cut off. CONSTITUTION:When a package unit 2, with leads 3 arranged extendedly, is located into a specifically positioned cavity 4 on a bend die 5, a lead press is moved down to fix a package unit in a state in which the leads 3 are put between the lead press and the lead receiving part 6 at their roots. Then, a mold punch is moved down to press the leads 3 downward against a punching surface 10, and followingly the leads 3 are put between the punching surface 10 and the forming surface 7 of the bend die 5, to be molded in prescribed shapes. Because a plurality of groove parts 8 are formed on positions corresponding to cutting margins 3a on the forming surface 7 of the bend die 5, thickness of the leads 3 put between the forming surface 7 and the punch 10 has only that of the original leads.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technique that is effective when applied to a lead molding die for molding external leads of flat package-shaped semiconductor devices and the like.

[Background technology] In lead forming for semiconductor devices, when bending the leads into a predetermined shape, the tie bars that connect each lead are cut out at the front, but this work involves shearing each tie bar with a cutting blade. It is done by doing. By the way, the cut allowance remaining on both sides of the lead after the tie bar is cut out is sheared in the thickness direction of the lead.
A protrusion called a burr is formed.

When a lead having such an irregularly shaped protrusion is bent using a mold material having a uniform molding surface, the thickness of the lead is effectively increased. Here, the final clamping distance of the lead by the mold material is set to a predetermined value by the original lead ring. Therefore, if bending is performed with the lead ring effectively increased as described above, an unreasonable bending force will be applied to the lead, and the sliding force of the shape material applied to the lead will increase, causing the lead to bend. The inventor has revealed that there is a possibility that the solder plating applied to the surface may peel off or the leads may be damaged.

Furthermore, even when looking at a single lead, if there is variation in the size of the protrusion of the cut margin on each side of the lead,
When bent with a mold, the predetermined directionality of each lead cannot be maintained accurately, resulting in variations in the pitch of the lead tips, resulting in poor appearance and even lowering the mounting reliability of semiconductor devices. At the same time, the inventor of the present invention clarified that.

An example of the technique described as a flat package type semiconductor device is "R Ultra Ls+ Device Handbook JP 224-P225, published by Science Forum Co., Ltd., November 28, 1980.

[Object of the Invention] An object of the present invention is to provide a technique that can prevent lead damage and perform highly reliable lead forming.

Another object of the present invention is to provide a technique that can manufacture a semiconductor device with high mounting reliability and no lead variation.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, by forming a concave portion on the molding surface of one of the molding materials for bending the lead and at a portion that abuts the cut margin from which the tie bar is cut, the protrusion of the cut margin that occurs during shearing of the tie bar is reduced. Since the lead can be pressed while housed in the recess, the lead thickness does not change effectively, and the bending force of the lead at the mold material can always be kept constant, which prevents plating peeling on the lead surface. It is possible to prevent damage such as

In addition, even if variations occur in the protrusions on both sides of each lead due to the above, the variations in the protrusions are absorbed by the recesses on the molding surface of the mold material, so the predetermined directionality of each lead is maintained accurately. It is possible to perform molding in a state in which the semiconductor device is in the same state as possible, and it is possible to manufacture a semiconductor device with high mounting reliability and no lead variation.

[Example] Fig. 1 is a perspective view showing a part of a lead molding die according to an embodiment of the present invention, and Fig. 2 shows the state of the lead molding die and the lead held therein at the time of bending. 3 (at, (bl, (cl) are schematic sectional views sequentially showing the lead molding process using this lead molding die.

The lead molding mold 1 of this embodiment is for molding leads of a flat package type semiconductor device, and is used to extend horizontally from a package body 2 or to bend a part 3 into an abbreviated shape. belongs to. In this embodiment, the package body 2, which is the object to be molded, is molded with resin, and the quiver that connects each lead 3 is cut out, and a lead molding mold is formed with the cut margin 3a remaining on the side of each lead. This is what is provided on the website.

The lead mold 1 has a bending die 5 in which a cavity 4 is formed for accommodating the package body 2, and a convex lead receiving part 6 is formed around the cavity 4. Furthermore, a diagonal L-shaped molded surface 7 is formed on the outer peripheral side of the lead receiver portion 6. In this embodiment, a plurality of grooves 8 are formed in the lead receiver from the part 5 to the molding surface 7, and the grooves 8 are formed as shown in FIG. 2 when the package body 2 is accommodated in the cavity 4. To, lead 3
It is formed at a position where the cut allowance 3a of the side portion comes into contact. Regarding the groove part 8, the size of the protrusion part 3b formed in the cutting allowance 3a, especially the protrusion part that is larger than the original thickness of the lead 3 in the protrusion part 3b, is determined by the second I.
As shown in 121, it is sufficient to have a depth that can absorb the amount of water in the bending direction, for example, about 0.05 μl to 0.1 μl.

Further, a lead presser 9 having a U-shaped cross section is located above the bending die 5, as shown in each figure in FIG.
A mold bunch 11 having a punch surface 10 corresponding to the punch surface 10 is positioned so as to be vertically movable.

Next, the operation of this embodiment will be explained. 6 First, the package body 2 with the lead 3 extending thereon is placed in the cavity 4 at a predetermined position on the bending die 5 ii! When placed (first
Figure and Figure 3 fal), the reed presser 9 is lowered,
The reed 3 is attached to the reed holder 9 at its root portion.
The lead receiver is held between the parts 6 and the package body is fixed (FIG. 3(b)).

Next, the mold punch 11 is lowered so that the punch surface 10 is aligned with the lead 3.
is pressed downward, and as a result, the board 3 is held between the punch surface 10 and the forming surface 7 of the bending die 5, and is formed into a predetermined shape (FIG. 3(C)). At this time,
In this embodiment, the forming surface 7 on the side of the bending die 5 has a cutting allowance 3a.
Since a plurality of grooves 8 are formed at positions corresponding to the grooves 8, as shown in FIG.
The protruding portion 3b of the cutting allowance 3a is housed in the groove portion 8. Therefore, the thickness of the portion of the lead 3 sandwiched between the molding surface 7 and the punching surface 10 is only the original thickness of the lead.

Therefore, since the mold bunch 11 can bend the glue portion 3 with a force set according to the original lead thickness, an excessive bending force is not applied to the lead 3, and the plating does not peel off. , damage to the glue portion 3 such as deformation can be prevented.

In addition, since the protrusions 3b are accommodated in the grooves 8 on the molding surface 7, even if there are variations in the protrusions 3b on both sides of each lead 3, the dispersion in the protrusions 3b will be reflected in the grooves 8 on the molding surface 7. This allows each lead 3 to be bent in a predetermined direction, that is, in a state in which the pitches of the leads 3 are accurately aligned at predetermined intervals. Therefore, it is possible to provide a semiconductor device with high mounting reliability in which the joint portion of each lead can be placed at an accurate position f2 with respect to the mounting portion of the mounting board without causing lead variations.

[Effect (1)] By forming a concave part in the molding process of one of the molds for bending the lead and in the area that abuts the cut allowance from which the tie bar is removed, the cut allowance that occurs during shearing of the tie bar can be reduced. Since the lead can be bent while the protruding part is housed in the recess, the lead bending force on the mold material can always be kept constant without effectively changing the lead thickness. Damage such as peeling of plating can be prevented.

(2) Even if variations occur in the protrusions on both sides of each lead due to (11) above, the variations in the protrusions are absorbed by the recesses formed in the molding material, so each lead maintains the predetermined directionality. Molding can be performed while maintaining accuracy, and a semiconductor device with high mounting reliability without lead variations can be manufactured.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the embodiment, a case has been described in which the package body is provided on the lead mold with the tie bars cut off, but this is not limited to the case where the tie bars are cut at the same time as the bending, that is, the bending punch has a cutting blade. It may be equipped with the following.

Further, although a case has been described in which the groove is formed only on the bending die side, the groove may be formed on the bending punch side.

Moreover, it is not limited to the groove part, and a recessed part may be formed at the part where the cutting allowance comes into contact.

[Field of Application] In the above explanation, the invention made by the present inventor was mainly applied to the field of application, which is a lead molding mold for a so-called flat package semiconductor device, but the present invention is not limited to this. This technique is also effective when applied to lead molding molds for package-shaped semiconductor devices such as plastic leaded chip carrier type semiconductor devices or other electronic components.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a part of a lead molding die according to an embodiment of the present invention, and FIG. 2 is a diagram showing the state of the lead molding die and the lead held therein during bending of the embodiment. Cross-sectional view, Figure 3 + a1
．． (BL, (C1 is a schematic cross-sectional view sequentially showing the lead molding process using this lead molding mold. 1... Lead molding mold, 2... Package body, 3.
...Lead, 3a...Cutting allowance, 3b...Protrusion, 4
... Cavity, 5... Bending die, 6... Lead receiver part, 7... Molding surface, 8... Groove part, 9... Lead holder, 10... Haunch surface, 11...・Type punch. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A lead molding die in which a lead from which a tie bar has been cut is bent between a mold material having a predetermined shape and molded to correspond to the shape of the mold material, wherein at least the lead is folded. A lead molding die characterized in that a recess is formed on the molding surface of one of the molding materials to be bent and at a portion that abuts the cut margin of the tie bar. 2. The lead molding mold according to claim 1, wherein the molding material comprises a bending die and a mold punch, and a recess is formed in the bending die.