JP3506957B2 - Lead frame manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead frame on which a semiconductor integrated circuit chip is mounted, and more specifically, a lead having an insulating tape attached adjacent to a wire bonding area of the lead frame. The present invention relates to a method for manufacturing a frame.

[0002]

2. Description of the Related Art The number of leads constituting a lead frame is increasing in response to demands for higher integration, higher functionality and smaller size of semiconductor devices. Along with this, the lead width and pitch are becoming finer. In particular, since the tips of the leads are miniaturized, deformation and displacement are likely to occur, and there is a risk of short-circuiting with adjacent leads. The lead frame may be manufactured by etching, but it is usually manufactured by progressive press molding.
This progressive feed press molding uses a die in which a plurality of press dies are arranged in an appropriate order and integrated, and a plurality of press dies corresponding to a plurality of press dies are sequentially fed while the thin plate material is progressively fed at a predetermined feed pitch. Is a method of manufacturing a lead frame by punching. Especially in the processing of the lead frame, in order to keep the pressing pressure uniform and prevent damage to the blade of the mold, a predetermined interval is set among the many gaps (punching parts) and the lead frame is The gap selected so as to be symmetrical with respect to the center of was simultaneously pressed.

Therefore, the gaps formed on both sides of each lead are not pressed at the same time, but are pressed separately. During press working, the periphery of the object to be processed (lead frame material) is pressed by the stripper, the gap between the parallel leads is punched by the punch, and one side surface of each lead is punched and formed, and then the other side The gap is stamped out. In this case, as shown in FIG. 5, the stripper 50 punches and forms the lead 51 punched on one side in a pressed state, and since the pressing area of the stripper 50 is small, the lead 51 is pushed to one side by the punching punch 52. The lead 51 was pulled in and twisted or residual stress was generated. In order to prevent the deformation of the lead 51 due to this residual stress, the lead frame is subjected to a heat treatment for removing the residual stress as needed during the manufacturing process. However, although the internal stress is removed by the heat treatment for removing the residual stress, there is a problem that the twist (roll) remains and the manufacturing cost is increased. In addition, after forming the lead pattern of the lead frame, flattening the wire bonding part at the tip of the lead and applying the required precious metal plating, a resin tape is attached to the position adjacent to the wire bonding part of the lead in a later process. It is also practiced to prevent the deformation of the leads by attaching the tape to the leads, and the tape attachment to the leads effectively reinforces the leads and keeps the interval between the adjacent leads as it is to prevent the deformation.

[0004]

However, the effect of this tape attachment is obtained when the tape is evenly attached to each lead formed around the semiconductor integrated circuit chip mounting portion, When the lead is formed in two steps as described above, the cross section of the lead 51 is twisted (rolled) on the side punched out in the subsequent step as shown in FIG. In the attached state, the adhesive layer varies on both sides of the lead 51, and as shown in FIG. 6, a difference in curing stress of the adhesive layer applied to the tape 53 on both sides of the lead 51 occurs, and the lead 51 shifts or moves. There was a problem of ups and downs. Therefore, the lead including the tape adhering region is preliminarily subjected to flattening processing by coining. However, although it is possible to flatten the leads,
Since the leads are twisted as described above, there have been problems that the leads are shifted or ups and downs due to the coining process, and the elongation and stress of the leads remain. The present invention has been made in view of the above circumstances, and does not require treatment such as coining and heat treatment in some cases, and further prevents twisting of the leads and extension of the leads in the tape adhering region, and thus the tape is evenly distributed. An object of the present invention is to provide a method for manufacturing a lead frame that can be attached.

[0005]

In the lead frame manufacturing method according to the present invention which meets the above object, a plurality of leads formed by punching are arranged around a semiconductor integrated circuit chip mounting portion, and the tips of the leads are arranged. In a method of manufacturing a lead frame having a wire bonding region in a portion and further including a tape adhering region to which a tape for connecting the leads is adhered, the lead punching forming process of the tape adhering region is performed by another method. This process is performed separately from the step of punching and forming parts, and the punching and forming process of the lead in the tape adhering region is performed by the simultaneous punching process that punches the gap between the leads at the same time.

Here, in the present invention, the tape adhering region is provided adjacent to the wire bonding region, and the width of the tape adhering region is at least substantially the same as the tape width. Is preferred. Further, the punching forming process of the lead frame in the portion other than the tape adhering area is performed by a normal progressive die, but in some cases, the portion other than the tape adhering area may be punched out at the same time. Thereby, both sides of the gap leads formed in tape applying area of the inner lead is punched at the same <br/>, the lead itself never be twisted to one side, more flatness is secured, the tape The adhesive strength is increased.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. 1 is a plan view of a lead frame manufactured by a method for manufacturing a lead frame according to an embodiment of the present invention, FIG. 2 is an enlarged view of the same portion, FIG. 3 is a sectional view taken along line BB in FIG. FIG. 4 is a plan view of the lead frame during the press working.

As shown in FIGS. 1 to 4, the lead frame 10 manufactured by the method according to the embodiment of the present invention is
It is formed by pressing a band-shaped metal material made of copper, a copper alloy or the like or a nickel alloy or the like, and has a semiconductor integrated circuit chip mounting portion 11 in the center. This semiconductor integrated circuit chip mounting portion 11 has four corners for hanging leads 1.
2 is supported by the semiconductor integrated circuit chip mounting portion 11
A large number of inner leads (an example of leads) 13 around the
However, an outer lead 14 is provided around the outer lead 14 so as to be continuous with each inner lead 13, and an outer frame 15 is provided outside the outer lead 14. The outer frame 15 is provided with a pilot hole 16 for positioning and carrying a strip material in which a plurality of lead frames 10 are connected. A tie bar 17 is provided at a connecting portion between each inner lead 13 and the outer lead 14, and adjacent inner leads 1
3 and the outer lead 14 are connected. The tie bar 17 and the outer frame 15 are separated at the time when the semiconductor device is assembled by using the inner lead 13 to separate and insulate the adjacent inner lead 13 and outer lead 14.

As shown in FIG. 2, each inner lead 13
The inner end portion (tip portion) of the wire-bonding region 1 on which gold plating, which is an example of noble metal plating, is performed
8 is formed, and the tape adhering area 19 is formed adjacent to the outside thereof.
Is provided. A polyimide resin tape 25 is adhered to the back surface (or front surface) of each inner lead 13 in the tape adhering region 19 so that the tip ends are in a free state and the inner leads 13 are kept at intervals and flatness. There is. The outer leads 14 shown in FIGS. 1 and 4 are usually gold-plated, silver-plated, or solder-plated so that a semiconductor device as a product can be mounted on a predetermined substrate and soldered. There is.

When the lead frame 10 is manufactured, a strip material made of a predetermined metal material is prepared and pressed to manufacture a lead frame intermediate material 20 as shown in FIG. In manufacturing the lead frame intermediate member 20, the front ends of the groups of the inner leads 13 on the four sides and the respective suspension leads 12 are connected by the connecting pieces 21 to 24. The connecting pieces 21 to 24 prevent deformation of the inner leads 13 during press working and ensure flatness. Here, the other part of the inner lead 13 excluding the tape adhering region 19 is pressed by a normal progressive die device. Then, as shown in FIG. 2, a punching process is performed on the gap 13c in the tape attaching region 19 that connects the gap 13b between the outer inner leads 13 and the gap 13a between the inner inner leads 13. Here, the gap 13c that is connected to the inner and outer gaps 13a and 13b
Has a width slightly smaller than the width of the connecting gaps 13a and 13b to prevent the generation of whiskers-like small pieces that occur during punching, and also secures the inner leads 13 of the wide tape attachment area 19. . The tape adhering region 19 is formed by the simultaneous punching process of the gap 13c. In this tape adhering area 19, since the cutting force is applied to both end portions of each inner lead 13 substantially evenly, there is no twist and a certain degree of flatness can be secured, and as will be described later, as shown in FIG. The tape 25 attached on one side is firmly joined. The parts other than the tape adhering area 19 may be punched by the inner lead 13 part or the outer lead 14 part first. It should be noted that it is free to perform annealing for removing the residual stress of the entire lead frame, if necessary.

Therefore, when the lead frame intermediate material 20 is manufactured, the tape 25 made of a polyimide resin formed in a rectangular frame shape is attached to the back surface side of the tape attachment area 19. The width of the tape 25 is substantially the same as the width of the tape adhering area 19. In attaching the polyimide tape, after the tape 25 is placed on the tape attaching area 19, the tape 25 is heated while being pressed against the inner lead 13 side, and the adhesive 25a previously applied to the tape 25 is used. It is attached (see FIG. 3). Adhesion of the tape 25 is effective for keeping the space between the inner leads 13 adjacent to each other and preventing their deformation or displacement. After this, the connecting pieces 21 to 24 are cut off by a pressing process, and each inner lead 13
After coining the wire bonding region 18 at the tip of the to obtain flatness and widen the area of that portion,
Gold plating, which is an example of precious metal plating, is performed. As a result, the lead frame 10 as shown in FIG. 1 is manufactured.

In the above-described embodiment, an example in which the present invention is applied to the lead frame 10 having the outer leads 14 has been described, but the present invention is also applied to a lead frame having no outer leads. Further, in the punching formation of the portion other than the tape adhering region 19 by press working, the case where the space (gap) on both sides of one lead is not punched simultaneously by the punch by the progressive die has been described. The present invention is also applicable to the case where the entire area other than the attachment area 19 or a portion divided into a specific area is punched at the same time.

[0013]

In the lead frame manufacturing method according to the first and second aspects of the present invention, since the tape adhering region of the inner lead is simultaneously punched and formed by press working,
The inner lead in that part does not twist or stretch,
Flatness is secured. As a result, the bonding strength of the tape stuck to the tape sticking area can be improved.
Particularly, in the inner lead manufacturing method according to the second aspect, the tape adhering region is provided adjacent to the wire bonding region, and the region width is formed at least substantially the same as the tape width. There is no waste, and only necessary parts can be punched simultaneously.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame manufactured by a lead frame manufacturing method according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the same portion.

3 is a sectional view taken along line BB in FIG.

FIG. 4 is a plan view of the lead frame during press working.

FIG. 5 is an explanatory view of a lead punching state according to a conventional example.

FIG. 6 is a cross-sectional view showing a pasted state of a lead and a tape according to a conventional example.

[Explanation of reference numerals] 10: lead frame, 11: semiconductor integrated circuit chip mounting portion, 12: suspension lead, 13: inner lead, 13
a to 13c: gap, 14: outer lead, 15: outer frame, 16: pilot hole, 17: tie bar, 18: wire bonding area, 19: tape attaching area, 20: lead frame intermediate material, 21 to 24: connection Piece, 25: Tape, 25a: Adhesive

Claims (2)

(57) [Claims] 1. A plurality of leads formed by punching are arranged around a semiconductor integrated circuit chip mounting portion, a wire bonding region is provided at a tip portion of the lead, and a tape for connecting the leads is attached. In the method of manufacturing a lead frame having a tape-attached region attached, the lead punching forming process of the tape attaching region is performed separately from the punching forming process of other parts, and the tape The lead punching forming process of the sticking region is performed by the simultaneous punching process of punching the gap between the leads at the same time, and the lead punching forming process between the leads in the tape sticking region is performed .
The gap is between the leads located inside and outside the tape attachment area.
Method for fabricating a lead frame, characterized that you have smaller than gap. 2. The lead frame manufacturing method according to claim 1, wherein the tape adhering region is provided adjacent to the wire bonding region, and the tape adhering region width is at least substantially the tape width. A method for manufacturing a lead frame, wherein the lead frame is formed to have the same dimensions.