JP2955043B2 - Method for manufacturing lead frame for semiconductor device - 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 for manufacturing a lead frame for a semiconductor device.

[0002]

2. Description of the Related Art Lead frames for semiconductor devices are manufactured by pressing metal materials or chemically etching metal materials. In either case, after forming the lead frame blank by press forming etc. to the final shape of the lead frame that should normally be obtained, perform the necessary plating, and furthermore, perform insulation so that the inner leads do not deform. The tape piece is attached to the inner lead. However, in recent years, since the number of pins has tended to decrease and the leads have become thinner, the inner leads may be deformed if a post-process such as plating is performed after processing to the final form of the lead frame as described above. Do not perform processing between the tip of the inner lead and the stage, apply the necessary plating while connecting it with a metal material during this time, and also stick a piece of tape, etc. I have to.

[0003]

However, if the tip of the inner lead is kept connected to the stage as described above, the tip of the inner lead is subjected to coining to secure a necessary bonding area. Therefore, there is a problem that deformation of the lead such as warpage of the lead occurs due to the inability to absorb the elongation of the inner lead caused by the lead. For this reason,
A method in which the ends of the inner leads are connected with a connecting piece, and this connecting piece is free from the stage. In this state, necessary processes such as coining, plating, and attaching a tape piece are performed, and finally the connecting piece is separated. There is also. According to this method, since the inner lead connected by the connecting piece is in a free state with respect to the stage, even if the tip of the inner lead is subjected to coining, the elongation due to the coining is absorbed, and the deformation of the lead can be prevented. . However,
In the case of pressing, 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 seized. In this case, however, in this case, the separated connecting piece is not caught in the die hole, so that the so-called scum phenomena easily occurs on the mold surface as the punch of the press rises, Damage the punch,
There is a problem that a dent is formed on the product. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to effectively absorb the elongation of inner leads caused by coining and to produce a lead frame for a semiconductor device without deformation. A method for manufacturing a frame is provided.

[0004]

The present invention has the following arrangement to solve the above-mentioned problems. That is, the tip of the inner lead of each group of the plurality of inner leads has a slit.
Are connected by that the connecting piece, and the blank forming step in which the connecting piece forms a stage or lead frame blank which is connected to the support bar of the stage for mounting a semiconductor element via the support piece, the inner lead tip of the lead frame blank A coining step of coining, a plating step of plating required portions of the lead frame blank, and a tape sticking step of sticking a tape piece having electrical insulation between inner leads after the coining step and the plating step. After the tape attaching step, a step of removing the connecting piece by separating the tip of the inner lead from the connecting piece and separating the supporting piece from the stage or the support bar is provided. In the blank forming process,
It is preferable to form the connecting piece over substantially the entire length of the connecting piece . It is preferable to perform a heat treatment on the lead frame blank to remove the internal residual stress. This is particularly effective when the blank forming step is performed by pressing.

[0005]

According to the method of manufacturing a lead frame for a semiconductor device according to the present invention, in the blank forming step of the first step, the inner lead destinations of each group of the plurality of groups of inner leads are set.
The ends are connected by a connecting piece having a slit, and the connecting piece
Is a stage for mounting a semiconductor element via a support piece or
Lead frame connected to the support bar of the stage
Since the blank is formed , the elongation of the lead when coining is applied to the tip of the inner lead,
Effective absorption by deformation of the connecting piece due to its presence
Thus , deformation of the lead can be prevented. Moreover, in the step of removing the connection piece, the connection piece is cut off between the inner lead and the connection piece and between the support piece and the stage or the support bar, that is, on both sides of the connection piece. Then, the die hole may be formed to the size of the connecting piece and the supporting piece to be cut, so that the separated connecting piece (and the supporting piece) is abutted and supported on the inner wall of the die hole and is spread over the die. It is possible to prevent the punch from being damaged and the occurrence of dents without rising.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First Step; Press Working FIG. 1 shows a lead frame blank 10 formed by press working. In this blank forming step , the metal strip-shaped members are sequentially punched by a press die by a progressive die to form the illustrated lead frame blank 10. 12 is an inner lead, 14 is a stage, and 16 is a support bar. An outer lead (not shown) is formed outside the inner lead 12 so as to be continuous with the inner lead. Other known elements such as a dam bar are formed on the lead frame blank 10. In this embodiment, a quad-type lead frame blank is shown, and the tips of the inner leads 10 of each of the four groups are connected by connecting pieces 18. This connecting piece 18 is connected to the stage 14 by a supporting piece 20. A slit 22 is formed in the connecting piece 18 over substantially the entire length of the connecting piece 18. Therefore, the connecting piece 18 and the supporting piece 20 are narrow.
They are connected by a unit 29. Support pieces 20 is formed in a narrow, which connects the substantially central portion of the corresponding side of the substantially central portion and the stage 14 of the coupling piece 18, also the support piece 2
A shallow notch 24 is formed on both sides of the support piece 20 on the side of the stage 14 to which 0 is connected. Second step; heat treatment Lead frame blank 10 formed as described above
Is subjected to a heat treatment to remove internal residual stress generated by press working. The heat treatment conditions vary depending on the type of the metal material, the shape of the lead frame blank 10, and the like.
Heat treatment is performed in an N ₂ atmosphere. Third step: coining Next, coining is performed on the tip of the inner lead 12. The coining process presses the tip of the inner lead 12 to flatten it and secure a necessary bonding area. Fourth Step; Plating Next, necessary plating such as silver plating and gold plating is performed on the inner lead 12, the stage 14, and the like. This plating is for improving wire bonding and die attachability. Fifth Step; Tape Adhesion Next, as shown in FIG. 1, a tape piece 28 made of polyimide resin or the like and having insulation and heat resistance is attached between the tips of the inner leads 12. Thereby, even after the connection 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 connection piece Next, the connection between the tip of the inner lead 12 and the connection piece 18 is cut, and the space between the support piece 20 and the stage 14 is cut to separate the connection piece 18 and the shape of the tip of the inner lead 12 is changed. Form.

In the blank forming step of the first step, the tips of the inner leads 12 of each group are connected by connecting pieces 18, slits 22 are formed in the connecting pieces 18, and the connecting pieces 18 are staged by supporting pieces 20. Since the connection piece 14 is connected, the elongation of the lead when the coining process of the third step is performed is effectively absorbed by the bending of the connecting piece 18, and the deformation of the lead can be prevented. This connecting piece 1
8 is also connected to the stage 14 via the support piece 20, but since the support piece 20 is narrow and the connecting piece 18 is provided with the slit 22, The resistance from the side narrows the narrow part 29
It is absorbed by bending and deformation of the lead can be prevented. The heat treatment in the second step releases the stress remaining in the lead frame blank 12 due to the press working, and prevents the deformation of the lead due to the residual stress when the connecting piece 18 is separated in a later step. In the sixth step of removing the connection piece 18, the connection piece 18 is cut between the inner lead 12 and the connection piece 18 and between the support piece 20 and the stage 14, that is, on both sides of the connection piece 18. When the pieces 18 are separated, the die holes may be formed to the size of the connecting pieces 18 and the supporting pieces 20 to be cut. Therefore, the separated connecting pieces 18 (and the supporting pieces 20) are separated.
However, the punch is not contacted and supported by the inner wall of the die hole and does not rise above the mold, so that damage to the punch and dents can be prevented. Further, since the provided notches 24 to the sides of the support piece 20 both sides of the stage 14, the sides and without hindrance cut somewhat mismatching of the support piece 20 die cut lines stage 14 to cut the I can do it.

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, the elongation of the inner lead 12 due to coining can be sufficiently absorbed, and deformation of the lead can be prevented.

[0009] The support piece 20 of the connecting piece 18 in the above embodiments
Is connected to the stage 14 via a support bar, but may be connected to the support bar 16 via a support piece (not shown). In this case, the same operation and effect as described above can be obtained. In the blank forming step of the first step, it is not always necessary to perform the pressing, but may be performed by a chemical etching. Of the above steps, the heat treatment in the second step, coining in the third step, and the plating step in the fourth step are not necessarily performed in the above order, and can be changed in any order. Further, in the above embodiment, the example of the quad type has been described, but it is needless to say that the present invention can be applied to the manufacture of a 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 blank forming step of the first step, each of the plurality of groups of inner leads is formed.
The tip of the inner lead of the group is
And the connecting piece is mounted on the semiconductor element via the supporting piece.
Connected to the stage or the support bar of the stage
Because it forms a lead frame blank which has been, Shin leads when subjected to coining the inner lead tip
Deformation of the connecting piece due to the presence of the slit
Thus, the lead can be effectively absorbed and the deformation of the lead can be prevented. Moreover, in the step of removing the connection piece, the connection piece is cut off between the inner lead and the connection piece and between the support piece and the stage or the support bar, that is, on both sides of the connection piece. To
Since the die hole may be formed to the size of the connecting piece and the supporting piece to be cut, the separated connecting piece (and the supporting piece)
However, the punch is not contacted and supported by the inner wall of the die hole and does not rise above the mold, so that damage to the punch and dents can be prevented.

[Brief description of the drawings]

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 the lead frame blank.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Lead frame blank 12 Inner lead 14 Stage 16 Support bar 18 Connecting piece 20 Support piece 22 Slit 28 Tape piece 29 Narrow part

Claims (4)

(57) [Claims] An end of each group of inner leads is connected by a connecting piece having a slit , and the connecting piece is connected to a stage for mounting a semiconductor element or a support bar of the stage via a supporting piece. Forming a formed lead frame blank, a coining step of coining the tip of an inner lead of the lead frame blank, a plating step of plating a necessary portion of the lead frame blank, and after the coining step and the plating step, A tape adhering step of adhering an electrically insulating tape piece between the leads, and a connecting piece for separating the tip of the inner lead from the connecting piece and separating the supporting piece from the stage or the support bar after the tape attaching step. A lead frame for a semiconductor device. Method for producing a beam. 2. The method according to claim 1, wherein in the blank forming step, the slit is formed.
2. The method of manufacturing a lead frame for a semiconductor device according to claim 1, wherein the step of forming is performed over substantially the entire length of the connecting piece . 3. The method for manufacturing a lead frame for a semiconductor device according to claim 1, further comprising a heat treatment step of performing a heat treatment on the lead frame blank 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 performed by press working.