JP2966070B2 - Lead frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lead frame.

(Prior Art) FIG. 10 is an explanatory view showing a conventional example of a lead frame. The lead frame is formed by repeatedly forming pieces including a die pad portion 10, a suspension lead 12, an inner lead 14, an outer lead 16, and the like as shown in the drawing.

A lead frame is usually made by pressing or etching a long body and then plating it to produce a product.The final product is obtained by cutting the long body into strips in a predetermined number of pieces. Usually, a large number of sheets, such as sheets, are stacked and provided.

FIG. 12 illustrates the vicinity of the die pad portion 10 of a lead frame cut and stacked in a strip shape. Since the die pad 10 and the like are formed in the same repetitive pattern on the lead frame, when the lead frames are overlapped, the die pad 10 and the suspension leads 12 are vertically stacked as shown in the figure.

In a post-process of mounting a semiconductor chip on a lead frame or the like, the stacked lead frames are picked up one by one and mounted on an apparatus. Therefore, when constructing an automation device, it is necessary to make it possible to easily pick up the lead frame from the stacked lead frames.

(Problems to be Solved by the Invention) By the way, in recent lead frames, as packages are becoming smaller and thinner, the number of products subjected to a press working in which the height position of a die pad portion is formed lower than the frame surface has increased. . FIG. 12 shows a state in which lead frames subjected to depressing are stacked. In the figure
13 is a depressing section. Depress part is hanging lead 12
A portion close to the die pad 10 is obliquely bent by press working.

FIG. 13 illustrates the stacked state of the suspension leads 12 in the vicinity of the depressed portion 13. Since a large number of lead frames are provided by stacking as described above, it is necessary to set the thickness of the depress portion 13 to be slightly thinner in order to stack without deformation. In this case, if the thickness of the depressed portion 13 is not set appropriately, a gap occurs between the upper and lower lead frames as shown in the figure, and the lead frame is deformed by the weight of the stacked lead frames. .

In addition, in a bent portion such as a depressed portion, plating leakage tends to occur, and therefore, when lead frames are stacked, biting due to plating flow is likely to occur in the depressed portion 13.

Furthermore, burrs are likely to be generated at the mismatched portion during the press working, and the burrs also make it easy for the stacked upper and lower lead frames to bite.

As described above, the lead frame provided with the depressed portion 13 is more likely to bite between the upper and lower lead frames when stacked than the lead frame not subjected to the depressing process. There is a problem that a failure is likely to occur.

Therefore, the present invention has been made to solve the above problems, and it is an object of the present invention to effectively prevent deformation of a lead frame even when a large number of sheets are stacked, and to facilitate pickup. It is intended to provide a lead frame.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, in a strip-shaped lead frame in which a lead and a plurality of pieces having a die pad portion supported by the frame by the suspension lead are arranged at regular intervals, at least two or more pieces in which the arrangement positions of the suspension leads are all different. One or more piece groups are arranged repeatedly in the longitudinal direction of the frame with the arrangement of the pieces in each piece group being the same, and the arrangement position of the suspension lead is
When the frames are stacked with the overlapping positions of the pieces coincident with each other, the frames are stacked so that the planar arrangement positions of the suspension leads do not overlap between the upper and lower pieces.

(Operation) By stacking the lead frames so that different piece patterns in which the suspension leads are displaced in the plane are vertically overlapped, the suspension leads are stacked without contact between the lead frames. Since the suspension leads do not come into contact between the laminated lead frames, biting at the suspension lead portions can be prevented, and the lead frames can be easily picked up from the laminated lead frames. In addition, the lead frame is prevented from being deformed by the weight of the lead frame when stacked.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing one embodiment of a lead frame according to the present invention. The lead frame shown in this embodiment is
Die pad part 10, inner lead 14, outer lead 1
6. The structure of the depressed portion 13 is the same as that of the lead frame of the conventional example shown in FIG. 10, but the position where the suspension lead 12 is formed is different from that of the conventional example.

That is, in the conventional lead frame shown in FIG. 10, the suspension lead 12 is usually designed to be located on the center line of the die pad portion 10, but in the present embodiment, the suspension lead is used.
The suspension lead 12 is shifted to one side of the center line P, and the position of the suspension lead 12 shifted from the center line is set up every other piece.

In the case of the piece A on the lead frame in FIG.
, The suspension lead 12 is shifted to the left of the center line P in the piece B. On the lead frame, the pattern of the piece A and the pattern of the piece B are alternately and repeatedly formed.

The purpose of setting the position of the suspension lead 12 shifted from the center line as described above is to prevent at least the depressed portion 13 from overlapping with the upper and lower lead frames when the lead frames are stacked and provided. .

FIG. 11 shows a state near a connection portion between the die pad portion 10 and the suspension lead 12 in a state where the lead frames shown in FIG. 1 are stacked. Although the A pattern and the B pattern are alternately formed on the lead frame as described above, when stacking lead frames, the A pattern and the B
A different kind of lead frame shifted by pieces is prepared, and the different kinds of lead frames are stacked up and down.

That is, a lead frame (hereinafter, referred to as a first frame) formed in a pattern of A → B → A → B.
The lead frames (hereinafter, referred to as second frames) formed in the pattern of → A → B → A... Are vertically stacked. As described above, when different types of lead frames are stacked, the positions of the suspension leads 12 are shifted and overlapped, so that the suspension frames can be stacked without contacting the suspension leads of the lead frame immediately above.

When the lead frames are stacked in this way, the eleventh
As shown in the figure, the die pad portion 10 is continuously stacked, but the A pattern and the B pattern are alternately provided at the portion of the suspension lead 12, so that a gap corresponding to the thickness of the lead frame is generated at the position of the suspension lead. become. 12a in Fig. 11
Is the suspension lead of the A pattern part on the lead frame, 12
b indicates a suspension lead of the B pattern portion.

As described above, by sequentially stacking the first frame and the second frame having different arrangement positions of the A pattern and the B pattern, the lead frames can be stacked without directly contacting the suspension leads 12.

As described above, the problem of sticking of the lead frames when picking up the stacked lead frames one by one often occurs in the suspension lead 12 portion, particularly in the depressed portion 13 portion. By preventing direct contact with the lead frame, sticking between the lead frames can be effectively prevented, and the lead frame can be easily picked up.

FIG. 14 illustrates a method for producing the above two types of lead frames by press working. In one method, A and B are formed by using two types of dies (press feed pitch of two pieces) for forming A pattern and B pattern.
The two types of lead frames in which the two patterns are formed into a long strip, and one piece of the end portion is cut and removed, and the end portion is cut off to change the arrangement of the piece patterns. To manufacture. That is,
When a certain number of pieces are sent, two kinds of lead frames are manufactured by cutting off one piece.

As another method, there is a method of manufacturing two types of lead frames by shearing a long body in which A patterns and B patterns are alternately formed in units of an odd number of pieces. According to this method, A → B without removing one piece
Since a lead frame having a pattern of → A → B... And a pattern of B → A → B → A. Of course, a method such as slit cutting may be used instead of cutting by shearing.

When a lead frame is manufactured by etching, a different lead frame can be easily manufactured by using an etching pattern in which the arrangement positions of the suspension leads are appropriately set.

2 to 9 show various embodiments of the lead frame according to the present invention. In the lead frame according to the present invention, the plane arrangement position of the suspension lead 12 is set so that the suspension lead 12 portion that is most likely to bite when stacked is not directly in contact with the upper and lower lead frames as described above. There are features. Thus, the hanging lead
The setting of the 12 forming positions can be appropriately changed according to the pattern of the lead frame, but specific examples are shown in FIG. 2 and subsequent figures.

The example shown in FIG. 2 is similar to the embodiment shown in FIG.
The suspension leads 12 supporting the die pad portion 10 are located on the opposite side of the same piece with the center line interposed therebetween. In the pattern A and the pattern B, the arrangement positions of the suspension leads 12 are reversed.

The example shown in FIG. 3 is an example in which the connection side to the die pad portion 10 is shifted from one halfway position of the suspension lead 12 to one side of the center line. FIG. 4 shows an example of a lead frame similar to FIG. 3, in which the direction in which the suspension leads 12 are shifted is reversed in the same piece. In both cases, the positions of the suspension leads 12 are reversed in the A pattern and the B pattern.

The example shown in FIG. 5 is a lead frame having a large area die pad portion 10 and a type having short suspension leads 12. Also in this case, the same effect can be obtained by displacing the suspension leads 12 to one side of the center line as in the above example. In the case of a lead frame that is supported by a very short suspension lead, the suspension lead
When the depressed portion 13 is formed on the lead 12, the length of the suspension lead 12 is restricted, so that the lead frame may not be bent at a required thickness or at a required angle which does not cause deformation when stacked. . In such a case, even if the required molding cannot be performed, contact of the suspension lead 12 can be avoided by shifting the position of the suspension lead 12 as described above, which is extremely effective.

The restriction on the bending angle of the suspension lead 12 is not limited to this embodiment, but is common to other lead frames. This has the advantage that the suspension lead can be easily formed. .

The embodiment shown in FIG. 6 is an example in which, when lead frames are stacked, one suspension lead is set so as to straddle the other suspension lead. That is, within the same piece, 2
One of the suspension leads 12 is arranged on the center line, and the other suspension lead 12 is bifurcated from the middle position and connected to the die pad 10. The gap formed in the middle of the branched suspension lead 12 is a part that escapes so that the suspension lead of another laminated lead frame does not contact.

FIG. 7 shows a lead frame having a large-area die pad portion 10 in which the die pad portion 10 is supported by two suspension leads 12. In this embodiment, the arrangement intervals of the two suspension leads 12 are set to be two types, that is, wide and narrow, and when the lead frames are laminated, the suspension leads at the narrow intervals are provided in the gaps between the large intervals of the A pattern and the B pattern. The suspension leads 12 are arranged so that they can be stacked without contact.

The lead frame shown in FIG. 8 is a lead frame similar to FIG. 7, in which the die pad part 10 is supported by two suspension leads 12, but the installation intervals of the suspension leads 12 are A and B with a wide difference. , C in three patterns.
The suspension leads 12 formed in the patterns A, B, and C are formed at wide and narrow intervals such that the suspension leads 12 do not contact each other when the lead frames are overlapped. In the case of this embodiment, the lead frame is cut and laminated in a strip shape including an integral multiple of 3 pieces. As described above, the number of patterns of pieces formed on the lead frame can be set to three or more.

FIG. 9 shows an embodiment of a quad type lead frame. In the lead frame of this embodiment, the suspension leads 12 are provided at the corners of the die pad portion 10 and supported by the frame, but the suspension leads 12 are displaced to one side of the diagonal line to shift the suspension leads in the same manner as in the above example. They can be stacked without contact. In the pattern A and the pattern B, the direction in which the suspension lead 12 is shifted is reversed.

In the lead frame, the suspension leads support the die pad portion and do not need to be formed at the same position in each piece as the inner leads do. Therefore, it is possible to form the suspension lead in various designs as described above. Also, it can be formed as appropriate according to the pattern of the inner leads and the like.

Further, in each of the above embodiments, the example in which the suspension lead is subjected to depressing is shown. The effect of the degree is exhibited.

In the lead frame of the above embodiment, a piece pattern in which the plane arrangement positions of the suspension leads are shifted from each other is provided on one lead frame.
It is also conceivable to separately prepare a lead frame composed of only the pattern pieces and a lead frame composed of only the B pattern, and to alternately laminate these different types of lead frames. In this case, a mold for the pattern A and a mold for the pattern B may be prepared and manufactured. Suitable for mass production of lead frames.

As described above, the present invention has been described variously with reference to preferred embodiments. However, the present invention is not limited to the above-described embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.

(Effect of the Invention) According to the lead frame of the present invention, when a large number of lead frames are stacked, the suspension leads are stacked without contact between the upper and lower lead frames, so that the sticking between the lead frames is eliminated. can do. As a result, the lead frame can be picked up smoothly. Furthermore, the lead frame subjected to the depressing process has a remarkable effect such as the fact that there is an advantage in manufacturing that the restriction such as the bending angle in the depressing process is eased.

[Brief description of the drawings]

1 is an explanatory view showing one embodiment of a lead frame according to the present invention, FIGS. 2 to 9 are explanatory views showing other embodiments of the lead frame, and FIG. 10 is a conventional example of a lead frame. FIGS. 11 and 12 are explanatory diagrams showing a stacked state of the present embodiment and a conventional lead frame, respectively.
FIG. 13 is an explanatory view showing a stacked state of hanging lead portions of a conventional lead frame, and FIG. 14 is an explanatory view showing a lead frame and a method of manufacturing the lead frame in the present embodiment. 10: die pad part, 12, 12a, 12b ... suspending lead, 13
...... Depress part, 14 ... Inner lead, 16 ... Outer lead.

Claims (1)

(57) [Claims] 1. A strip-shaped lead frame in which a lead and a plurality of pieces each having a die pad portion supported on the frame by the suspension lead are arranged at regular intervals, wherein at least two or more arrangement positions of the suspension leads are different. One or more piece groups including the pieces are repeatedly arranged in the longitudinal direction of the frame with the arrangement of the pieces in each piece group being the same, and the arrangement positions of the suspension leads are matched with the overlapping positions of the pieces. A lead frame, wherein when the frames are stacked, the suspension leads are stacked so that the planar arrangement positions of the suspension leads do not overlap between the upper and lower pieces.