JPH03181156A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To prevent occurrence of deformation of a lead and damage of a progressive metal mold by performing processing so that a third region part crosses first and second punch region parts. CONSTITUTION:Four third punch parts 20 forming an outline 1C in the middle of a bar 15 spaced wider than an outline 1A of a support bar 15 crossing a side wall 1B of a second punch part 18 and formed by a first punch region are formed wherein a tie bar 17 provided perpendicularly is cut off, tips 1D of inner leads 13 are formed and gaps between the leads 13 are divided and formed to have a lead frame completed. Thus since outlines of punch regions of respective parts do not align with each other, occurrence of deformation of a lead and damage of a progressive metal mold can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a lead frame, and particularly to a method for manufacturing a lead frame using a multi-step progressive mold.

(Prior Art) A lead frame for a 1'-73 device is formed by shaping a metal strip 441-1 by either photo-etching or pressing.

In particular, for lead frames formed by press working, it is difficult to mold all the inner leads in one punching process, so it is necessary to use a progressive die and divide the leads into multiple stations. is set to 1.

However, in recent lead frames, the lead pitch and width tend to be narrower than the thickness of the tip of the inner lead. For example, the thickness of the lead frame is 0.15+! +m, 0, l
Punching may have to be done with a width of ~0.12 mm. Therefore, in order to prevent the positional shift of the tips of the inner leads, the shape is processed by leaving a connecting part that connects the tips of adjacent inner leads, and a taping process, heat treatment, or plating process is performed to connect the inner leads to each other. A method has been proposed in which the connecting portion is finally removed after the treatment process.

This method is usually carried out in the following steps.

For example, conventionally, as shown in FIG.
A plurality of first punched portions 5A converge toward the area that will become the semiconductor element mounting stage 52 using a progressive die.
are formed, and the side surfaces of the inner leads 51 are formed, as well as support bars 53 that support the semiconductor element mounting stage 52.

After this, from the tips of the plurality of first punched parts 5A,
Connection part of inner lead 51 tip 5F (tie bar 54)
At a predetermined interval corresponding to the area where
A punched portion 5B is formed.

Then, with the tips 5F of the inner leads 51 integrally connected by the tie bars 54, predetermined treatments such as heat treatment and plating are performed.

Further, as shown in FIG. 4(b), a third punching part 5D is formed using the second progressive die, the tie bar 54 provided perpendicular to the support bar is cut out, and the inner Form the tip F of the lead 51 and give it a split shape,
A lead frame as shown in the overall view in FIG. 5(b) is completed. In this method, the third punching area matches the contour line of the support bar formed in the first punching area and the side edge of the support bar formed in the second punching area, and the side edges of the support bar are aligned in a straight line. It is formed so that

(Problem to be Solved by the Invention) The lead frame formed by such a method is not suitable for the first punching process depending on conditions such as the clearance of the punch and die constituting the progressive die, the surface condition of the workpiece, and the positioning accuracy. It has been extremely difficult to punch out the third punching area so that it accurately matches the contour line of the support bar formed in the area and the side edge of the support bar formed in the second punching area. Therefore, depending on the slight displacement of the position, minute punching dregs, punching sag, whisker-like punching pieces, etc. are likely to occur, and these can fall onto the surface of the workpiece and cause scratches or deformation of the lead. It was causing this.

Moreover, it may cause damage to the mold, leading to an increase in the cost of lead frames and a decrease in yield.

Furthermore, as semiconductor devices become more highly integrated, the number of pins increases, and the width of the support bar becomes narrower, making it difficult to properly support the stage on which semiconductor elements are mounted, causing twisting during the press punching process, etc. There is a problem that deformation occurs due to stress caused by resin sealing or the like.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a high quality and low cost lead frame.

(Means for Solving the Problems) Therefore, in the method of the present invention, unnecessary parts of a metal strip material are sequentially punched out using a progressive die, a semiconductor element mounting part and the semiconductor element mounting part are supported, and the outer part is punched out. a support bar extending toward the semiconductor element mounting portion; a plurality of inner leads extending at predetermined intervals from the periphery of the semiconductor element mounting portion;
In the lead frame handling process in which the shape of the lead frame is processed, which includes an outer lead connected to each inner lead, first, an overlap part is formed to form the tip of the inner lead. , after forming a plurality of first punching regions that constitute the contours of a plurality of inner leads and sabot bars extending from the vicinity of the semiconductor element mounting stage formation region, and then forming a contour of a support bar formed by the first punching regions. The contour of the support bar extends in the direction of the contour line, leaving a cross area between the contour line of the support bar and the first punched area at a distance from the contour line of the support bar, without matching the extension line of the line. A second punching area is formed that has a side edge that forms part of the wire and forms a tip connection part that connects the element mounting stage and the adjacent inner lead tip, and finally, this tip connection part is punched out. The first and second punched areas intersect at a predetermined angle with the outline of the support bar so as to form the tip of the inner lead and cut the cross area in the direction in which the support bar extends. A third punched region is formed having side edges forming part of the support bar contour extending in the same direction as the support bar contours of the first and second punched regions.

(Function) According to the present invention, when performing punching, the contour lines of the punching areas of each part are made to intersect at a predetermined angle so that they do not coincide with each other, so even if a slight deviation occurs, the punching It can be formed without generating scraps, punching, whisker-like punched pieces, etc., and it is possible to prevent dents, deformation of the lead, and damage to the progressive die.

Further, if the support bars formed in the second and third punching regions are formed so that the distance between the contours of the support bars is larger than the distance between the contours of the support bars formed in the first punching region, the semiconductor Since the connecting part between the element mounting stage and the support bar is wide, the support bar is reinforced to prevent twisting during the pressing process and deformation due to stress caused by resin sealing, etc. can.

(Example) Hereinafter, a method for manufacturing a lead frame according to an example of the present invention will be described in detail with reference to the drawings.

Embodiment 1 In the lead frame of the first embodiment of the present invention, a support bar 15 has a connecting region 15a extending from the semiconductor element mounting portion, and protrudes on both sides in the width direction of both the connecting region and the support bar. It is characterized in that it is connected to the semiconductor element mounting part 14 via the wide part 1.5b.

First, as shown in FIG. 1(a), a strip material containing copper as a main component is passed through a first progressive die (not shown) equipped with a die for cutting out inner leads, outer leads, dam bars, etc. of desired shapes. By attaching the first punched portions to the inner leads 13 and performing press processing, a plurality of first punched portions 12 are formed that converge toward the region that will become the semiconductor element mounting stage 14, forming the side surfaces of the inner leads 13, and forming the semiconductor element mounting stage 14. A support bar 15 that supports the mounting stage 14 and an outer lead 22 are formed. 11 is a frame body.

After this, it has a side edge 1B that does not coincide with the extension line of the contour edge IA of the support bar but extends in the same direction, and from the tip of the plurality of first punched parts 12 to the connection part (tie bar) of the tip 1D of the inner lead 13 17) Four second punched portions 18 are formed at predetermined intervals along the four sides of the region that will become the semiconductor element mounting stage 14. In this way, as shown in the overall view in FIG. 2(a), an intermediate stage lead frame having four cross areas 19 surrounded by the first punched part 12 and the second punched part 18 is obtained. It will be done.

Then, predetermined treatments such as heat treatment and plating treatment are performed while the tips IDs of the inner leads 13 are integrally connected by the tie bars 17.

Further, as shown in FIG. 1(b), using a second progressive die, the side edge IB of the second punched portion 18 is
four third punched parts forming a contour line of the middle part of the support bar 15 which intersects with the contour line 1A of the support bar 15 and is wider than the interval between the contour lines 1A of the support bar 15 formed in the first punched area 12; 20, the tie bar 17 provided perpendicular to the support bar is cut off, and the tip ID of the inner lead 13 is formed.
By dividing the lead frame 177, a lead frame as shown in FIG. 2(b) is completed. In this method, the side edge of the third punched area does not match the contour line of the support bar formed in the first punched area and the side edge of the support bar formed in the second punched area, and The side edges of the support bar are formed to form orthogonal sections.

According to the lead frame formed in this way, the contour lines of the punched areas of each part do not match each other, and even if a slight deviation occurs, punching residue, punching sag, whiskers-like punching pieces, etc. will occur. It can be formed without any occurrence of dents, deformation of the lead, and damage to the progressive die. In addition, since a protrusion is formed on the outline at the connecting part of the support bar of the semiconductor element mounting stage 14, the strength of the support bar is improved and it becomes possible to prevent twisting and deformation of the semiconductor element mounting stage. .

Example 2 Next, a second embodiment of the present invention will be described.

In this example, the support bar 35 includes a first wide portion 35a that projects on both sides in the width direction of the support bar, and a first wide portion 35a that protrudes on both sides of the support bar in the width direction.
It is characterized in that it is connected to the semiconductor element mounting portion 34 via second wide portions 35b that protrude further to both sides of the wide portion.

That is, the side edge of the third punched area located in the middle is made to protrude from the outline of the support bar formed in the first punched area and the side edge of the support bar formed in the second punched area, and The support bar is characterized in that the side edge of the support bar is formed so as to form a part perpendicular to the protrusion.

In manufacturing, first, as shown in FIG. 3(a), a strip material mainly composed of copper is passed through a first progressive die equipped with a die for cutting out inner leads, outer leads, dam bars, etc. of desired shapes. By attaching it to a mold (not shown) and performing press processing, a plurality of first punched parts 32 are formed that converge toward the area that will become the semiconductor element mounting stage 34, and the side surfaces of the inner leads 33 are formed. With,
Support bar 3 that supports the semiconductor element mounting stage 34
5 and outer leads 31 are formed.

After this, if there is a side edge 3B that does not coincide with the extension line of the contour edge 3A of the support bar but extends in the same direction,
From the tips of the plurality of first punched parts 32, the semiconductor element mounting stage 3
Four second punched portions 38 are formed along the four sides of the region 4, respectively. In this way, Figure 2(a)
An intermediate stage lead frame having three four cross regions surrounded by a first punching 32 and a second punching 38 is obtained, as shown in the general view in FIG.

Then, with the tips 3D of the inner leads 33 integrally connected by the tie bars 37, predetermined treatments such as heat treatment and plating treatment are performed.

Further, as shown in FIG. 3(b), using a second progressive die, the side edge 3B of the second punched portion 38 is
and four thirds forming a contour line 3C of the middle part of the support bar 35 with a wider interval than the interval of the contour line 3A of the support bar 35 formed in the first punched area 32.
A punched portion 30 is formed, the tie bar 37 provided perpendicular to the support bar is cut out, and the tip 1D of the inner lead 33 is formed. The frame is completed.

In this method, the contour lines of the support bar formed in the first punching region and the side edges of the support bar formed in the second punching region do not coincide with the side edges of the third punching region, but are perpendicular to each other. The side edges of the support bar are formed to form a portion that

According to the lead frame formed in this way, the contour lines of the punched areas of each part do not coincide too much; 1. Even if a slight deviation occurs, it can be formed without producing punching scum, punching sag, whisker-like punching pieces, etc., and it is possible to prevent dents, deformation of the lead, and damage to the progressive die. .

Furthermore, since the protrusion is formed on the contour of the support bar, the strength of the support bar is improved, and it becomes possible to prevent twisting and deformation of the semiconductor element mounting stage.

Further, in the above embodiment, copper was used as the lead frame material, but it goes without saying that the material is not limited to copper and other materials may be used.

Furthermore, regarding the shape of the molding area in each process,
It can be changed as appropriate.

〔Effect of the invention〕

As explained above, according to the lead frame manufacturing method of the present invention, when shaping a strip material into the shape of a lead frame, the outlines of the plurality of punched areas forming the outline of the support bar do not match. Since the third punching area intersects with the first and second punching areas to form a common area, even if a slight deviation occurs, there will be no punching residue or punching. It can be formed without any droop or whisker-like punched pieces, etc.
It is possible to prevent the occurrence of dents, deformation of the lead, and damage to the progressive die.

Furthermore, since the protrusion is formed on the contour of the support bar, the strength of the support bar is improved, and it becomes possible to prevent twisting and deformation of the semiconductor element mounting stage.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are partial explanatory views showing the manufacturing process of the lead frame of the first embodiment of the present invention, and FIG.
Figures (a) and 2 (b) are overall explanatory diagrams showing the manufacturing process of the lead frame, and Figures 3 (a) and 3 (b).
) is a partial explanatory view showing the manufacturing process of a lead frame according to the second embodiment of the present invention, FIGS. 4(a) and 4(b) are partial explanatory views showing the manufacturing process of a conventional lead frame,
FIG. 5(a) and FIG. 5(b) are overall explanatory diagrams showing the manufacturing process of the lead frame. 51... Inner lead, 52... Semiconductor element mounting stage, 53... Support bar 54... Tie bar 5A... First punched part, 5F... Tip, 5B
...Second punching part, 5D...Third punching part, 11...Frame body, 12...First punching part, 13
...Inner lead, 14...Semiconductor element mounting stage, 15...Support bar 17...Tie bar
18...Second punching part, 1...Cross region, 2
2...Outer lid, lA...contour edge, IC...
Contour line, ID... tip, 20... third punched part, 31... outer lead, 32... first punched part, 33... inner lead, 34... semiconductor element Mounting stage 5... Support bar 7... Tie bar 38... Second punching part. (Q) (b) Figure 1 ○ ○ ○ ○ ○ Figure 2 (a) Figure 2 (b) Figure 5 (Q) (a) Figure 3 (b) Figure 4

Claims (1)

[Scope of Claims] Using a progressive die, unnecessary portions of a metal strip material are sequentially punched out, a semiconductor element mounting portion, a support bar supporting the semiconductor element mounting portion and extending outward, and the semiconductor element mounting portion; A lead frame punching process for shaping a lead frame comprising: a plurality of inner leads extending from the periphery of an element mounting part at predetermined intervals; and outer leads connected to each inner lead. In the process, a plurality of first punched area portions including an overlap portion for forming the tip portions of the inner leads and forming the contour lines of the plurality of inner leads and support bars extending from the vicinity of the semiconductor element mounting stage forming area are formed. a first punching step to form a support bar; and a first punching step that does not coincide with an extension of the contour of the support bar formed in the first punching step, but at a slight distance from the contour of the support bar. The support bar has a side edge forming a part of the contour line of the support bar extending in the direction of the contour line so as to leave a cross area between the support bar and the support bar, and connects the element mounting stage and the adjacent inner lead tip. The second
a second punching step of forming a punching region of the first and second punching portions, punching out the tip connecting portion to form the inner lead tip portion, and cutting the cross region in the extending direction of the support bar;
a portion of the support bar contour line that intersects at a predetermined angle with the support bar contour line of the punched area and extends in the same direction as the support bar contour line of the first and second punched area; A method for manufacturing a lead frame, comprising a third punching step of forming a third punching region having side edges forming a lead frame.