JPH09129813A - Lead frame and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame provided with a heat dissipating plate of excellent quality, and a semiconductor device using the same. SOLUTION: This lead frame is provided with a die pad 2 for mounting a semiconductor chip, a lead frame main body part having a plurality of inner leads 3 arranged in the outer peripheral part of the die pad, outer leads stretching from the inner leads, and a heat dissipating plate 18 which is in contact closely with the lower surface of the die pad 2 and dissipates heat. A plurality of protrusions 26 formed on the lower surface of the die pad 2 are forcibly engaged with recesses or through holes 27 of the heat dissipating plate 18. Thereby the lead frame main body part and the heat dissipating plate 18 are fixedly unified in a body. The lead frame provided with the heat dissipating plate, a semiconductor chip fixed and mounted on the die pad 2, and the inner leads 3 are connected together by using bonding wires. The part inside the inner leads 3 is packaged by using sealing material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame with a heat radiating plate, which is formed on a die pad and a heat radiating plate. Regarding the device.

[0002]

2. Description of the Related Art A lead frame used for mounting a semiconductor device such as an IC or an LSI is formed by molding a thin strip of an iron-based or copper-based metal material into a desired shape by stamping or etching. It

Usually, the lead frame 1 integrally connects the die pad 2, a plurality of inner leads 3 arranged so as to surround the die pad 2, and the inner lead 3 as shown in FIG. A tie bar 4, an outer lead 5 that is connected to each inner lead 3 and extends outside the tie bar 4, a side rail 6 to which the outer lead 5 is connected, and a support bar 7 that supports the die pad 2. As shown in FIG. 6, in the semiconductor device, each electrode of the semiconductor chip 15 fixedly mounted on the die pad 2 of the lead frame 1 and the corresponding inner lead 3 are connected by a gold wire or an aluminum wire. After connecting with a bonding wire-16 and packaging the inside of the inner lead 3 with a sealing material, the tie bar 4 Cutting the pre said side rail 6, and the outer leads 5 protruding from the package 17 is completed by bending into a desired shape.

In recent years, as semiconductor integrated circuits have become more multifunctional and highly integrated, the semiconductor chip size and the die pad supporting the semiconductor chip have also become larger, while the external size of the package has become smaller. Is large, the adhesion between the die pad and the sealing resin is poor, and the thermal expansion coefficient is different.Therefore, if continuous thermal stress is applied by the heat generation of the semiconductor chip, peeling at the interface between the die pad and the sealing resin may occur. Chip cracks, package cracks, and the like are occurring, which lowers the reliability of the semiconductor device.

Therefore, particularly in a semiconductor device that consumes a large amount of power and generates heat accordingly, as shown in FIG. 7, a heat sink 18 made of metal having excellent thermal conductivity is attached to the lower surface of the lead frame by an insulating adhesive material 19. The lead frame having the heat radiating plate 18 is fixed in the resin package and built in the resin package, so that the heat generated in the semiconductor chip is positively and efficiently discharged to the outside, and an excessive temperature rise inside the semiconductor device is suppressed. However, a method of maintaining a stable function without changing its characteristics is generally practiced.

[0006]

However, in the semiconductor device having the above-mentioned structure, when the lead frame body and the heat sink are fixed to each other, as described above,
An insulating adhesive with a thermoplastic or thermosetting adhesive layer formed on both sides is used.This adhesive has a hygroscopic property, and this property allows moisture to enter the inside of the semiconductor device. Then, the heat history during the assembly process of the semiconductor device and the temperature rise accompanying the operation of the semiconductor device cause the moisture to evaporate and expand, generating bubbles and gas to cause peeling at the resin interface, package cracks, and internal leads. Cause the corrosion of the semiconductor device, and the functional characteristics and reliability of the semiconductor device are significantly impaired.

Further, since the adhesive material used in this case is very expensive, it also causes a rise in the manufacturing cost and the product price. The present invention has been made in view of the above circumstances,
By preventing the moisture absorption phenomenon inside the semiconductor device due to the adhesive material and ensuring sufficient moisture resistance, it is possible to maintain stable function and reliability for a long period of time, and it has excellent quality. An object is to provide a semiconductor device.

[0008]

The features of the present invention for achieving the above object are that a die pad on which a semiconductor chip is mounted, a plurality of inner leads provided on the outer periphery of the die pad, and extending from the inner leads. In a lead frame including a lead frame main body portion having an outer lead and a heat dissipation plate that adheres to the lower surface of the die pad to dissipate heat, a plurality of convex portions formed on the lower surface of the die pad are provided. The heat dissipation characterized in that the lead frame main body and the heat dissipation plate are fixedly integrated by fitting and press-fitting into the recess or the through hole of the heat dissipation plate formed at a position facing each other and corresponding to the projection. A lead frame with a board,
The semiconductor chip fixedly mounted on the die pad and the inner lead are connected by a bonding wire,
There is a semiconductor device in which the inside of the inner lead is packaged with a sealing material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a lead frame main body portion having a plurality of convex portions formed on a lower surface of a die pad,
A heat dissipation plate facing the convex portion and having a concave portion or a through hole at a position corresponding to the convex portion is fixedly integrated by fitting the convex portion and the concave portion or the through hole formed respectively. Therefore, no adhesive is used to fix the lead frame body and the heat sink, and the moisture absorption phenomenon inside the semiconductor device due to this adhesive does not occur. Therefore, peeling of the resin interface due to moisture absorption as in the past,
Various problems such as package cracks and lead corrosion do not occur.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a plan view of a lead frame main body portion showing a first embodiment of the present invention. The same figure (b) is the sectional view.
FIG. 3C is a plan view of the heat sink. The same figure (d) is the sectional view. FIG. 2 is a sectional view of a semiconductor device showing a first embodiment of the present invention. FIG. 3 is a sectional view of a lead frame with a heat sink showing a second embodiment of the present invention, and FIG. 4 is a sectional view of a lead frame with a heat sink showing a third embodiment of the present invention. FIG. 5 is a plan view of a lead frame showing a conventional technique. FIG. 6 is a sectional view of a semiconductor device showing a conventional technique. FIG. 7 is a cross-sectional view of a lead frame with a heat dissipation plate showing a conventional technique. 1 to 4, parts that are the same as or correspond to those in the conventional technique are denoted by the same reference numerals.

In the embodiment of FIG. 1, a plurality of convex portions 26 are formed on the lower surface of the die pad 2 of the lead frame main body portion 25, and one heat radiating plate 18 faces the convex portions 26 and A concave portion 27 or a through hole (not shown) is formed at a position corresponding to the convex portion 26, and when the convex portion 26 is press fitted into the concave portion 27 or the through hole, the lead frame main body portion 25 and the heat radiating plate 18 are formed. It is possible to complete the lead frame with the heat radiating plate according to the present invention by mechanically joining and fixing the and.

In the semiconductor device according to the present invention shown in FIG. 2, the semiconductor chip 15 is fixedly mounted on the upper surface of the die pad 2 of the lead frame with the heat radiating plate, and its terminals and a plurality of inner leads 3 provided on the outer periphery of the die pad 2. Via the bonding wire 16, and then the die pad 2 within the inner lead 3, the semiconductor chip 15 and the bonding wire 1
6 and 6 can be packaged with a sealing resin, and then the outer leads 5 projecting from the package 17 can be bent into a desired shape to be completed.

In the above embodiment, the lead frame body 25 and the heat dissipation plate 18 are made of copper alloy, respectively. However, the materials to be used and the combination thereof are not limited to this. For example, the lead frame main body 25 is made of 42 alloy material having a thermal expansion coefficient relatively close to that of the semiconductor chip, and the heat dissipation plate 18 is made of copper alloy or aluminum alloy. be able to.

Next, in the above-described embodiment, the convex portion 26 on the lower surface of the die pad 2 is fitted and press-fitted into the concave portion 27 or the through hole of the heat radiating plate 18, and fixed in this case.
If a conductor layer such as Ag paste is applied to the recesses 27 or through holes of the die pad and the other areas contacting the lower surface of the die pad 2, the die pad 2 and the heat radiating plate 18 are fixed when they are fixed.
No gap is created between the die pad 2 and the heat sink 18
At the same time as the fixing force with the heat dissipation plate is increased, the conductivity to the heat dissipation plate 18 is also improved.

Further, in the case where the heat dissipation plate 18 is formed with a through hole, the tip of the convex portion 26 is crushed from one of the through holes fitted with the convex portion 26 on the lower surface of the die pad 2. It is also possible to apply a small amount of the adhesion strengthening material, and the fitting state with the lead frame main body portion 25 and the heat dissipation plate 18 becomes even stronger.

Furthermore, when the sealing resin enters into the through hole during packaging, the adhesion between the heat sink 18 and the sealing resin is further improved, and heat stress is applied to the heat sink 18. Can also alleviate this.

Next, the plurality of convex portions 26 formed on the lower surface of the die pad 2 are formed by general press working, and a predetermined area on the upper surface of the die pad is pressed by a punch in the mold. The lower surface is projected by a desired amount to form the convex portion 26. Therefore, when the convex portion 26 is formed on the lower surface of the die pad 2 by press working, at the same time, the concave portion 35 is formed on the upper surface of the die pad 2 at a position facing the convex portion 26.

When the die pad 2 and the semiconductor chip 15 are fixed to each other, the recess 35 is formed when a liquid or fluid adhesive such as resin or Ag paste applied to the die pad 2 leaks out of the bonding area of the semiconductor chip. Also,
The adhesive is allowed to enter the concave portion and dammed to prevent leakage to other areas.

Furthermore, when the encapsulating resin enters the recess 35 during packaging, the adhesiveness between the die pad and the encapsulating resin is improved, and the die pad and the encapsulating resin interface are strongly resistant to peeling due to thermal stress. Can be kept in good condition.

In the above-mentioned embodiment, the convex portion 26 is formed by pressing in view of productivity and manufacturing cost. However, the forming method is not limited to this, and it may be formed by etching, for example. Well, in particular, when it is desired to form the convex portion 26 without exerting stress on the die pad, the etching process is effective.

Further, the recess 27 or the through hole of the one heat radiating plate 18 can also be formed by using a pressing or etching processing method like the projection 26.

In the above embodiment, the lead frame with heat sink plate of the present invention is formed by fitting the protrusions 26 formed on the lower surface of the die pad 2 and the recesses 27 or through holes formed on the heat sink plate 18, respectively. Although the fitting convex portion and the concave portion or the portion where the through hole is formed are not limited to the above-described embodiment, for example, a plurality of convex portions 36 are formed on the heat dissipation plate 18 as shown in FIG. The convex portion 36 on the lower surface of the die pad 2
A concave portion 37 at a position facing the convex portion 36 and corresponding to the convex portion 36.
May be formed, and the respective convex portions 36 and concave portions 37 may be fitted and fixedly integrated with each other. Further, as shown in FIG. 4, through holes 38 may be formed in the die pad 2 to form the convex portions 36 of the heat dissipation plate 18.
It may be fitted and fixed.

Also in this case, if a conductor layer of Ag paste or the like is formed in advance in the convex portion 36 of the heat sink 18 and in the other regions contacting the die pad 2, the die pad 2 and the heat sink 18 are fixed to each other when they are fixed. There is no gap between them, and the fixing force between the die pad 2 and the heat sink 18 is increased, and at the same time, the heat sink 1
The conductivity to 8 is also improved.

Further, when the through hole 38 is formed in the die pad 2 and is fitted with the convex portion 36 of the hot plate 18, the one of the through holes with which the convex portion 36 is fitted is If the tip of the convex portion 36 is crushed or a slight amount of the adhesion enhancing material is applied, the fitting state can be further strengthened.

[0025]

As described above, according to the present invention, the lead frame main body portion having a plurality of convex portions formed on the lower surface of the die pad, and the concave portion at a position facing the convex portion and corresponding to the convex portion, Since the convex portion and the concave portion or the through hole formed on each of the heat dissipation plates having the through holes are fitted and fixedly integrated, there is no need to use an adhesive material. Therefore, in the semiconductor device using the lead frame with the heat dissipation plate, the moisture absorption phenomenon related to the adhesive does not occur, and the resin interface peels,
It does not cause package cracks, corrosion of internal leads, etc., sufficient moisture resistance can be secured, and the adhesion strength between the constituent parts inside the semiconductor device and the sealing resin has been improved. A semiconductor device with excellent quality that can maintain reliability can be obtained.

[Brief description of the drawings]

FIG. 1 (a) is a plan view of a lead frame main body showing a first embodiment of the present invention. (B) It is sectional drawing of the lead frame main-body part which shows the 1st Example of this invention. (C) It is a top view of the heat sink which shows the 1st Example of this invention. (D) It is sectional drawing of the heat sink which shows the 1st Example of this invention.

FIG. 2 is a sectional view of a semiconductor device showing a first embodiment of the present invention.

FIG. 3 is a sectional view of a lead frame with a heat radiating plate showing a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a lead frame with a heat sink according to a third embodiment of the present invention.

FIG. 5 is a plan view of a lead frame showing a conventional technique.

FIG. 6 is a cross-sectional view of a semiconductor device showing a conventional technique.

FIG. 7 is a cross-sectional view of a lead frame with a radiator plate showing a conventional technique.

[Explanation of symbols] 1, lead frame 2, die pad 3, inner lead 4, tie bar 5, outer lead 6, side rail 7, support bar 15, semiconductor chip 16, bonding wire 17, package 18, heat dissipation Plate 19, Insulating Adhesive 25, Lead Frame Main Body 26, Die Pad Lower Surface Convex 27, Heat Dissipator Recess or Through Hole 35, Die Pad Top Recess 36, Heat Sink Convex 37, Die Pad Bottom Recess

Claims (6)

[Claims] A die pad on which a semiconductor chip is mounted;
A lead including a lead frame main body portion having a plurality of inner leads provided on the outer periphery of the die pad and outer leads extending from the inner leads, and a heat dissipation plate that adheres to the lower surface of the die pad to dissipate heat. In the frame, a plurality of convex portions are formed on the lower surface of the die pad, and the heat dissipation plate is provided with a concave portion or a through hole at a position facing the convex portion and corresponding to the convex portion. Lead frame characterized by. 2. A plurality of convex portions formed on the lower surface of the die pad of the lead frame main body are fitted in concave portions or through holes of a heat radiating plate formed at positions corresponding to the convex portions and facing the convex portions. The lead frame according to claim 1, wherein the lead frame main body and the heat dissipation plate are fixedly integrated with each other by press fitting. 3. A die pad on which a semiconductor chip is mounted;
A lead including a lead frame main body portion having a plurality of inner leads provided on the outer periphery of the die pad and outer leads extending from the inner leads, and a heat dissipation plate that adheres to the lower surface of the die pad to dissipate heat. In the frame, a plurality of convex portions are formed on the lower surface of the die pad, and the heat dissipation plate has a concave portion or a through hole formed at a position facing the convex portion and corresponding to the convex portion. Alternatively, by fitting and press-fitting the convex portion into the through hole, the lead frame main body portion and the heat sink are fixedly integrated, and the semiconductor chip fixedly mounted on the die pad and the inner lead are connected by a bonding wire. A semiconductor device in which the inside of the inner lead is packaged with a sealing material. 4. A die pad on which a semiconductor chip is mounted;
A lead including a lead frame main body having a plurality of inner leads provided on the outer periphery of the die pad and outer leads extending from the inner leads, and a heat dissipation plate that adheres to the lower surface of the die pad to dissipate heat. In the frame, a plurality of convex portions is formed on the upper surface of the heat dissipation plate, and a concave portion or a through hole is formed on the lower surface of the die pad so as to face the convex portion and correspond to the convex portion. Lead frame characterized by 5. A plurality of convex portions formed on the upper surface of the heat dissipation plate are press-fitted into concave portions or through holes on the lower surface of the die pad formed at positions corresponding to the convex portions and corresponding to the convex portions. 5. The lead frame according to claim 4, wherein the lead frame body and the heat sink are fixedly integrated with each other. 6. A die pad on which a semiconductor chip is mounted,
A lead including a lead frame main body portion having a plurality of inner leads provided on the outer periphery of the die pad and outer leads extending from the inner leads, and a heat dissipation plate that adheres to the lower surface of the die pad to dissipate heat. In the frame, a plurality of convex portions is formed on the upper surface of the heat dissipation plate, and a concave portion or a through hole is formed on the lower surface of the die pad so as to face the convex portion and correspond to the convex portion. By fitting and press-fitting the convex portion into the concave portion or the through hole, the lead frame main body portion and the heat dissipation plate are fixed and integrated, and the semiconductor chip fixedly mounted on the die pad and the inner lead are bonded to each other by a bonding wire. And a semiconductor device in which the inside of the inner lead is packaged with a sealing material.