JPH04280661A - Manufacture of semiconductor device lead frame - Google Patents

Abstract

PURPOSE:To obtain a lead frame which is free of deformation absorbing the expansion of lead effectively by a method wherein the tips of inner leads of every group are interlinked together by a linking piece, the linking piece is connected to a stage or a support bar with an index piece, and the linking pieces are bent. CONSTITUTION:The tips of inner leads 12 of every group are interlinked together by a linking piece 18, a slit is provided to the linking piece 18, and furthermore the interlinking piece 18 is connected to a stage 14 with index pieces 20 and 29, so that the interlinking piece 18 and the support piece 29 are bent to absorb the elongation of the inner leads 12. The interlinking piece 18 is connected to a stage 14 through the intermediary of the index piece 20, the index piece 20 is narrow in width, and the slit is provided to the interlinking piece 18, whereby the inner lead 12 can be protected against deformation. Moreover, as stress residual in a lead frame blank 10 due to a press work is eliminated through a thermal treatment, leads are prevented from being deformed due to residual stress.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing lead frames for semiconductor devices.

0002

2. Description of the Related Art Lead frames for semiconductor devices are manufactured by pressing metal materials or by chemically etching them. In either case, the final shape of the lead frame is usually formed by pressing, etc. to form a lead frame blank, and then the necessary plating is performed, and insulating material is applied to prevent the inner leads from deforming. A piece of tape is attached to the inner lead. However, in recent years, there has been a trend towards increasing the number of pins and the leads are becoming thinner, so if you perform post-processes such as plating after processing the lead frame to its final form as described above, there is a risk that the inner leads may become deformed. , no processing is performed between the tip of the inner lead and the stage, the necessary plating is applied while the inner lead tip and the stage are connected with a metal material, and the shape of this space is processed after pasting the tape piece etc. I have to.

0003

[Problem to be Solved by the Invention] However, if the tip end of the inner lead is left connected to the stage as described above, the coining process is performed on the tip of the inner lead to ensure the necessary bonding area. Unable to absorb the growth of the inner lead due to coining,
There is a problem that deformation such as warping of the lead occurs. For this reason, the tip of the inner lead is connected with a connecting piece, and this connecting piece is made free from the stage, and the necessary processes such as coining, plating, and pasting of tape pieces are performed in this state, and finally the connecting piece is separated. There is also a way to do it. According to this method, the inner lead connected by the connecting piece is in a free state with respect to the stage, so even if the tip of the inner lead is coined, the elongation due to the coining process is absorbed and deformation of the lead can be prevented. . however,
In the case of press working, when the connecting piece is finally separated, the connecting piece is in a free state, so the die hole of the mold for removing the connecting piece is set to be larger than the connecting piece, and the connecting piece is scraped. However, in this case, the separated connecting pieces do not get caught in the die hole and tend to fly up onto the mold surface as the punch of the press rises, resulting in a reduction in so-called scrap lifting. damage the punch,
There is a problem in that it causes dents on the product. Therefore, the present invention has been made to solve the above problems, and its purpose is to provide a lead for semiconductor devices that can effectively absorb the elongation of the inner lead due to the coining process and produce a lead frame without deformation. To provide a method for manufacturing frames.

0004

Means for Solving the Problems The present invention has the following configuration to achieve the above object. That is, in a method for manufacturing a lead frame for a semiconductor device, the inner lead tips of each group of a plurality of inner leads are connected by a connecting piece, and the connecting piece is connected to a stage for mounting a semiconductor element or a stage for mounting a semiconductor element through an indicator piece. a blank forming process forming a lead frame blank connected to the support bar;
a coining process of coining the tips of the inner leads of the lead frame blank; a plating process of plating necessary parts of the lead frame blank; a tape pasting process of pasting pieces of insulating tape between the inner leads; The present invention is characterized by comprising a connecting piece removal step of separating the lead tip from the connecting piece and separating the indicator piece from the stage or support bar. It is preferable to form a slit extending almost the entire length of the connecting piece in the blank forming process. Preferably, the lead frame blank is heat treated to remove internal residual stresses. This is particularly effective when the blank forming process is by press working.

[0005]

[Operation] According to the method of manufacturing a lead frame for a semiconductor device according to the present invention, in the first blank forming step, the tips of the inner leads of each group are connected by a connecting piece, and this connecting piece is connected by an indicator piece. Since it is connected to the stage or support bar, the elongation of the lead when coining is applied to the tip of the inner lead is effectively absorbed by the bending of the connecting piece, and deformation of the lead can be prevented. By providing a slit in this connecting piece, the resistance from the stage side due to the extension of the lead can be absorbed by the effect of the slit, and deformation of the lead can be prevented. In addition, in the process of removing the connecting piece, cutting is performed between the inner lead and the connecting piece and between the indicator piece and the stage or support bar, that is, on both sides of the connecting piece.
When separating the connecting pieces using a press mold, the die hole can be formed to the size of the connecting piece and the indicator piece to be cut, so the separated connecting piece (and the indicator piece) can be attached to the inner wall of the die hole. This prevents the punch from flying upwards due to contact with the mold, which prevents damage to the punch and the occurrence of dents.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. First step: Pressing FIG. 1 shows a lead frame blank 10 formed by pressing. In this blank forming process, metal strip members are sequentially punched out using a progressive press die to form the lead frame blank 10 shown in the drawing. 12 is its inner lead, 14 is a stage, and 16 is a support bar. Outer leads (not shown) are formed outside the inner leads 12 and are continuous with the inner leads. In addition, known elements such as a dam bar are formed on the lead frame blank 10. In this example, a quad-type lead frame blank is shown, with one on each of the four sides.
The tips of the inner leads 10 of the group are connected by a connecting piece 18. This connecting piece 18 is connected to the stage 14 by an indicator piece 20. Further, a slit 22 is formed in the connecting piece 18 over almost the entire length of the connecting piece 18. The support piece 20 is formed narrowly and connects approximately the center of the connecting piece 18 and the approximately center of the corresponding side of the stage 14, and also has an indicator piece on the side of the stage 14 to which the support side 20 connects. Shallow notches 24 are formed on both sides of 20. Therefore, the connecting piece 18 and the indicator piece 20 are connected through an extremely narrow portion. In addition, the connecting portion between the connecting piece 18 and the supporting piece 20 is made narrower, and the slit 22 side of the supporting piece 20 is designed to absorb as much deformation as possible due to elongation of the lead when coining the tip of the inner lead. A notch may be provided in the. Second step: Heat treatment Lead frame blank 10 formed as described above
Heat treatment is applied to remove internal residual stress caused by press working. This heat treatment condition varies depending on the type of metal material, the shape of the lead frame blank 10, etc.
2 Perform heat treatment in an atmosphere. Third step: Coining Next, the tip of the inner lead 12 is subjected to a coining process. This coining process presses the tips of the inner leads 12 to make them flat and to secure the necessary bonding area. Fourth step: Plating Next, necessary plating such as silver plating or gold plating is performed on the inner leads 12, stage 14, etc. This plating is for improving wire bonding properties and die attachment properties. Fifth step: Attaching the tape Next, as shown in FIG. 1, an insulating and heat-resistant tape piece 28 made of polyimide resin or the like is attached between the tips of the inner leads 12. As a result, even after the connecting piece 18 is removed, the inner lead 12 is fixed by the tape piece 28, so that deformation can be prevented. Sixth step: Removal of the connecting piece Next, cut between the tip of the inner lead 12 and the connecting piece 18, cut between the indicator piece 20 and the stage 14, separate the connecting piece 18, and determine the shape of the tip of the inner lead 12. Form.

In the first blank forming step, the tips of the inner leads 12 of each group are connected by a connecting piece 18, a slit 22 is formed in the connecting piece 18, and the connecting piece 18 is further moved to a stage by an indicator piece 20. 14, the elongation of the lead during the coining process in the third step is effectively absorbed by the bending of the connecting piece 18, and deformation of the lead can be prevented. This connecting piece 1
8 is also connected to the stage 14 via the indicator piece 20, but since the indicator piece 20 is narrow and the connecting piece 18 is provided with a slit 22, the stage 14 due to the extension of the lead. Resistance from the sides is also absorbed by the effect of the slits 22, and deformation of the leads can be prevented. The heat treatment in the second step releases stress remaining in the lead frame blank 12 due to press working,
When the connecting piece 18 is separated in a later process, deformation of the lead due to residual stress is prevented. In the sixth step of removing the connecting piece 18, between the inner lead 12 and the connecting piece 18 and between the indicator piece 20 and the stage 14, that is, the connecting piece 18
Since the cutting is performed on both sides of the connecting piece 18, when separating the connecting piece 18 using a press die, the die hole can be formed to the size of the connecting piece 18 and the indicator piece 20 to be cut. 18 (and the indicator piece 20) are not directed to come into contact with the inner wall of the die hole and fly upwards of the mold, thereby preventing damage to the punch and occurrence of dents. In addition, notches 2 are provided on the sides of the stage 14 on both sides of the indicator piece 20.
4, even if the cutting line of the mold for cutting the indicating side 20 is slightly mismatched with the side of the stage 14, cutting can be performed without any problem.

FIG. 2 shows another embodiment. This embodiment is the same as the above embodiment except that the connecting piece 18 is not provided with a slit. Even without providing a slit, by making the connecting piece 18 narrow, it is possible to sufficiently absorb the elongation of the inner lead 12 due to the coining process, thereby preventing deformation of the lead.

In each of the above embodiments, the connecting piece 18 is replaced by the indicator piece 20.
In this embodiment, the support bar 14 is connected to the stage 14 through the support bar 16, but the support bar 16 may be connected to the support bar 16 through an indicator piece (not shown). In this case as well, the same effects as described above are achieved. The blank forming step of the first step does not necessarily have to be press working, but may be chemical etching. Further, among the above steps, the heat treatment in the second step, the coining process in the third step, and the plating step in the fourth step do not necessarily have to be in the above order, and can be changed in any order. Further, although the above embodiments have been explained using an example of a quad type, it is of course applicable to manufacturing DIP type and other types of lead frames.

0010

According to the method of manufacturing a lead frame for a semiconductor device according to the present invention, as described above, in the first blank forming step, the tips of the inner leads of each group are connected by connecting pieces, Since this connecting piece is connected to the stage or support bar by the indicator piece, the elongation of the lead when coining is applied to the tip of the inner lead is effectively absorbed by the bending of the connecting piece, preventing deformation of the lead. It can be prevented. By providing a slit in this connecting piece, the resistance from the stage side due to the extension of the lead can be absorbed by the effect of the slit, and deformation of the lead can be prevented. In addition, in the process of removing the connecting piece, the connecting piece is cut between the inner lead and the connecting piece and between the indicator piece and the stage or support bar, that is, on both sides of the connecting piece, so when separating the connecting piece using a press mold. Since the die hole can be formed to the size of the connecting piece and the indicator piece to be cut, the separated connecting piece (
and the indicator piece) are directed to come into contact with the inner wall of the die hole and do not fly upwards of the mold, thereby preventing damage to the punch and occurrence of dents.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of a lead frame blank showing a first embodiment.

FIG. 2 is a partial plan view showing another embodiment of a lead frame blank.

[Explanation of symbols]

10 Lead frame blank 12 Inner lead 14 Stage 16 Support bar 18 Connecting piece 20 Instruction piece 22 Slit 28 Piece of tape

Claims (4)

[Claims] 1. In a method for manufacturing a lead frame for a semiconductor device, the inner lead tips of each group of a plurality of groups of inner leads are connected by a connecting piece, and the connecting piece is connected to a stage or a stage for mounting a semiconductor element through an indicator piece. a blank forming process for forming a lead frame blank connected to a support bar of the stage; a coining process for coining the inner lead tips of the lead frame blank; and a plating process for plating necessary parts of the lead frame blank. The method includes a tape attaching step of attaching an insulating tape piece between the inner leads, and a connecting piece removal step of separating the inner lead tip from the connecting piece and separating the indicator piece from the stage or support bar. A method for manufacturing lead frames for semiconductor devices. 2. The method of manufacturing a lead frame for a semiconductor device according to claim 1, further comprising the step of forming a slit extending substantially over the entire length of the connecting piece in the blank forming step. 3. The method of manufacturing a lead frame for a semiconductor device according to claim 1, further comprising a heat treatment step of subjecting the lead frame blank to heat treatment to remove internal residual stress. 4. The method for manufacturing a lead frame for a semiconductor device according to claim 1, wherein the blank forming step is a press working step.