JPH0513652A - Lead frame - Google Patents

Abstract

PURPOSE:To prevent a warp in a die pad part by forming a cut-off part in a supporting bar, and sticking the die pad part side of the separated supporting bar and an inner lead with a self-adhesive tape so that a distortion during the manufacturing or caused by thermal contraction can be attenuated. CONSTITUTION:An end of inner leads 18 is put closely around a die pad part 12 provided for mounting a semiconductor chip. A supporting bar 20 or 21 is elongated from a peripheral part of a lead frame 10 for supporiting the die pad part 12. At least one of the supporting bars 20 and 21 is cut off and a cut-off part 24 is made therein. Then, one of the separated supporting bar 21 near the die pad part 12 and the inner lead 18 are stuck with an self-adhesive tape 22. By this means, distortion during the dimple work or caused by thermal contraction is abosrbed so that the deformation in the die pad part 12 can be prevented. Consequently, the lead frame can meet the requirement of a mutiple pin structure and so on.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lead frame,
More specifically, the present invention relates to a lead frame in which a die pad portion for mounting a semiconductor chip is supported by a support bar extending from a peripheral portion of the lead frame.

[0002]

2. Description of the Related Art Conventionally, as a lead frame on which a semiconductor chip is mounted, for example, a dip type lead frame shown in FIG. 2 has been used. In the lead frame 100 shown in FIG. 2, the die pad portion 12 on which the semiconductor chip is mounted is supported by the support bars 20 and 21 that connect the rail portions 26 and 26, and the peripheral edges thereof project from the dam bars 14 and 14. Inner lead 18,
At the tip of 18 ... Also, the dam bars 14 and 1
On the side opposite to the inner lead side of 4, the outer lead 1
6 and 16 are formed. Such a dam bar 1
A portion surrounded by the rails 14, 14 and the rail portion 26 is a region which is resin-sealed after the semiconductor chip mounted on the die pad portion 12 and the tips of the inner leads 18, 18 ... Are bonded. In the resin-sealed lead frame, the portions corresponding to the gaps between the inner leads 18 of the dam bars 14, 14 are cut, and the inner leads 18 and the outer leads 16 are connected to each other into a single wire. The plurality of holes 28 formed in the rail portions 26, 26 are positioning holes for the lead frame 100.

[0003]

In the conventional lead frame 100 shown in FIG. 2, since the die pad portion 12 on which the semiconductor chip is mounted is supported by the support bars 20 and 21, after mounting the semiconductor chip, It is possible to support the semiconductor chip at a predetermined position when bonding the tips of the inner leads 14, 14, ... And the semiconductor chip. However, since the semiconductor chip and the die pad portion 12 are bonded to each other through an adhesive or the like, the die pad portion 12 is subjected to dimple processing or the like so that the die pad portion 12 is provided with irregularities and the two are bonded well. . At that time, processing strain is applied to the die pad portion 12. Further, during resin sealing, heat is applied to the lead frame 100 from the sealing resin, but in general, there is a thermal contraction difference between the metallic lead frame 100 and the sealing resin. Distortion may occur in the die pad portion 12 due to such processing distortion and distortion due to the difference in heat shrinkage.

In order to prevent the distortion of the die pad portion 12 from occurring, the support bar 20 (or the support bar 2
As shown in FIG. 3, a part of 1) is S-shaped [FIG. 3 (a)].
Alternatively, by forming a Y-shaped deformed portion (FIG. 3B), it has been attempted to absorb strain due to processing strain, thermal contraction, etc. by the deformation of the deformed portion. However,
As shown in FIG. 3, in order to form the deformed portion in a part of the support bar 20 (or the support bar 21), a space for forming the deformed portion is needed, and the lead frame 100 of the lead frame 100 is increased in accordance with the high integration of semiconductor chips. At the present time when a large number of pins and the like are required, the formation density of the inner leads 18, 18 ... Can not be made dense, which is unsuitable. Further, when the gap between the inner leads 18, 18 ... Narrows with the increase in the number of pins of the lead frame 100, the sealing resin supplied from one surface side of the lead frame 100, the inner leads 18, 18. It becomes difficult to flow through the gap between them to the other surface side of the lead frame 100, and the inclination of the die pad portion 12 due to the resin pressure difference easily occurs.

Therefore, the present invention absorbs the processing strain caused by the dimple processing or the like and the strain caused by the difference in heat shrinkage to prevent the distortion of the die pad portion, and easily meets the demands such as the increase in the number of pins. The purpose is to provide a lead frame that can be used.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies to achieve the above-mentioned object, and as a result, cut at least one of a plurality of support bars that support a die pad portion having a dimple process or the like. By doing so, I learned that the processing strain can be released without distorting the die pad part. Even if at least one of the support bars is cut, the same strength as before cutting the support bar is maintained by attaching the die pad side of the cut support bar together with the inner lead with adhesive tape. They have found the present invention and reached the present invention.

That is, according to the present invention, in a lead frame in which the inner lead tips are provided close to the periphery of the die pad portion on which a semiconductor chip is mounted, a plurality of lead frames extending from the periphery of the lead frame to support the die pad portion are provided. A lead ram is characterized in that at least one of the support bars of the book is formed with a cut portion, and the die pad portion side of the cut support bar is attached together with the inner lead with an adhesive tape. In the present invention having such a configuration, when the lead frame is inserted into the cavity of the resin sealing mold, the cutting portion of the support bar is positioned so as to be located in the vicinity of the vent port for venting the air in the cavity. By being provided, it is possible to easily prevent the occurrence of inclination of the die pad portion due to the resin pressure difference.

[0008]

According to the present invention, the strain caused by the processing such as the dimple processing of the die pad portion and the difference in heat shrinkage can be absorbed by the cut portion of the support bar, and the distortion of the die pad portion caused by the strain is supported. It can be avoided without forming the bar into a special shape. Furthermore, even if the inner leads are densely formed and the gaps between the inner leads are significantly narrowed, making it difficult for the sealing resin to flow from one surface side of the lead frame to the other surface side of the lead frame, The sealing resin can easily flow from the cut portion to the other surface side, and the inclination of the die pad portion due to the resin pressure difference can be prevented. Further, the decrease in the strength of the die pad portion due to the cutting of the support bar can be sufficiently compensated by adhering the die pad portion side of the cut support bar together with the inner lead with an adhesive tape.

[0009]

The present invention will be described in more detail with reference to the drawings. 1 is a front view showing an embodiment of the present invention, and a lead frame 10 shown in FIG. 1 is a dip type lead frame. The lead frame 10 is the same as that shown in FIG.
Since the lead frame is of the same type as the lead frame 100 shown in FIG. 2, the description of the same parts as the lead frame 100 of FIG. 2 will be omitted. In this embodiment, the die pad portion 1
Of the support bars 20 and 21 that support 2, the support bar 21 is cut to form a cut portion 24. The cutting portion 24 is provided so as to be located in the vicinity of a vent port for venting air in the cavity when the lead frame 10 is inserted into the cavity of the resin sealing mold. Further, in the present invention, the support bar 20 connected to the die pad portion 12 side of the support bar 21 provided with the cut portion 24 and the rail portion 26 is provided with the inner leads 18 by the adhesive tapes 22 made of polyimide resin. It is attached together with 18 ... Since the strength and the like of the die pad portion 12 are strengthened by sticking the adhesive tapes 22 and 22, when performing processing such as dimple processing on the die pad portion 12 or mounting a semiconductor chip on the die pad portion 12 and performing bonding with a bonding tool. When performing, the die pad portion 12 can exhibit sufficient strength. The adhesive tapes 22 and 22 can strengthen the die pad portion 12 and the like, and can also prevent deformation due to the cut support bars 21 and the inner leads 18, 18 ...

In the lead frame 10 shown in FIG. 1, a semiconductor chip is mounted on the die pad portion 12 and is bonded between the inner leads 18, 18 ... At the time of resin encapsulation, the lead frame 10 is inserted into the cavity of the resin encapsulation mold, and encapsulating resin is supplied to one surface side of the lead frame 10 in the direction of arrow A shown in FIG. The sealing resin supplied to one surface side of the lead frame 10 is supplied to the other surface side of the lead frame 10 through the gap between the inner leads 18, 18 ... And the cutting portion 24. At this time, in order to meet the demand for increasing the number of pins, the inner lead 1
If the formation density of 8, 18 ... Is made dense and the gap between the inner leads 18, 18 ... Is made extremely narrow, the amount of resin passing through the gap between the inner leads 18, 18 ... A resin pressure difference is generated between the surfaces of the frame 10, and the die pad portion 12 is likely to be inclined. In this respect,
In the present embodiment, the sealing resin is easily supplied to the other surface side of the lead frame 10 from the cutting portion 24, and the resin pressure difference is unlikely to occur, so that the inclination of the die pad portion 12 can be prevented. The resin-sealed lead frame 10 is taken out from the resin-sealing mold after the sealing resin has solidified and cooled, and corresponds to the gap portion between the inner leads 18, 18 of the dam bars 14, 14. The parts are separated.

In the present embodiment, the cutting portion 24 is formed on the support bar 21 side, but it may be formed on the support bar 20. In addition, the adhesive tape 22 is the cutting portion 2.
4 is also attached to the support bar 20 on which the cutting portion 24 is not formed, but the support bar 21 on which the cut portion 24 is formed.
It may be just the side. Further, the present embodiment shows an example in which the die pad portion 12 is applied to a dip type lead frame supported by two support bars 20 and 21.
Of course, it can also be applied to a QUAD TYPE lead frame in which the die pad part is supported by four support bars.

[0012]

According to the present invention, it is possible to prevent the die pad portion from being distorted due to the processing such as dimple processing of the die pad portion and the difference in heat shrinkage with the sealing resin, and it is possible to improve reliability of the lead frame. In addition, since it is possible to prevent distortion of the die pad portion due to the resin pressure difference of the sealing resin between the lead frame surfaces, which is caused by the miniaturization of the gap between the inner leads accompanying the densification of the inner lead formation density, it is possible to increase the pin count It is possible to easily meet such requests.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a front view showing a conventional lead frame.

FIG. 3 is a partial front view illustrating a known improvement example of the lead frame shown in FIG.

[Explanation of symbols]

10 lead frame 12 Die pad part 18 Inner lead 20 Support bar 21 Cut support bar 22 Adhesive tape 24 cutting part

Claims (2)

[Claims] 1. A lead frame in which a tip of an inner lead is provided close to a peripheral edge of a die pad portion on which a semiconductor chip is mounted, and a plurality of support bars extending from the peripheral edge portion of the lead frame to support the die pad portion. At least one of the above has a cut portion, and the die pad portion side of the cut support bar is attached together with the inner lead with an adhesive tape. 2. The support bar is provided such that the cut portion is located near a vent port for venting air in the cavity when the lead frame is inserted into the cavity of the resin sealing mold. The lead frame according to claim 1, wherein