JPH06224363A - Semiconductor device and manufacture thereof the same - Google Patents

Abstract

PURPOSE:To ensure excellent heat radiating effect and high reliability by providing a lead frame body including an inner lead and an outer lead and a semiconductor element mounting part coupled with the end part of the inner lead. CONSTITUTION:A lead frame is constituted by a lead frame body including an inner lead 1 and an outer lead 3 and a semiconductor element mounting part 2 made of an aluminium plate with both front and rear surfaces coated with aluminum oxide layer 2S. The rear surface of the semiconductor element mounting part 2 is exposed from sealing resin 9. The end portion of inner lead 1 is joined with the semiconductor element mounting part 2 through an insulating bonding agent. A semiconductor chip 5 is coupled with the inner lead 1 by a bonding wire 6. Moreover, the external side is sealed with a sealing resin 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a lead frame structure for mounting a semiconductor integrated circuit chip.

[0002]

2. Description of the Related Art With the miniaturization and higher integration of semiconductor devices, the inner lead tips of lead frames have become thinner,
Deformation is becoming more likely to occur. Such deformation of the inner leads is apt to cause short-circuiting of the leads and defective bonding, which is one of the causes of lowering the yield of the lead frame and lowering the reliability of the semiconductor device.

By the way, as the number of pins increases, the lead pitch of the inner leads becomes smaller and the manufacturing technique becomes more difficult. In addition, the tip of the inner lead is easily deformed and the distance between the tip of the inner lead and the semiconductor chip is increased. Since the length of the bonding wire becomes long, there is a problem that the bonding wire is deformed during molding and short-circuits.

In addition, since the temperature of the power element is increased, the heat radiation performance greatly affects the element characteristics.

Therefore, even when the density is increased, it is intended to provide a semiconductor device having high reliability, and the chip mounting portion is made of a material having a good heat dissipation property separately from the lead frame body, and the tip of the inner lead is formed. There has been proposed a method of joining the chip mounting portion to the above.

In this method, the lead frame main body and the chip mounting portion can be formed of different materials in consideration of workability and heat dissipation, respectively, and the tip of the inner lead is supported by the chip mounting portion to prevent deformation. The effect of being able to do is effective.

Further, as the output of the semiconductor element tends to be higher, the number of leads of the lead frame used for this also increases and the amount of heat generation also increases. Therefore, as shown in FIG. In addition, there is also proposed a semiconductor device in which this heat dissipation plate is exposed on the back surface of the sealing resin package.

The heat radiating plate 7 used here is mainly made of a copper-based material having good heat conduction, and is provided in the central portion of the inner lead.
The two surfaces are joined by a polyimide tape 14 coated with an adhesive. However, in such a lead frame, there is a limit in thinning the polyimide tape 14 between the heat dissipation plate 7 and the lead frame main body, and this thickness serves as a cushion between the inner lead and the heat dissipation plate, and a capillary is used for bonding. However, there is a problem that the ultrasonic wave is attenuated, reliable wire bonding cannot be performed, and the wire bondability is deteriorated. Further, the thickness of the polyimide tape 14 and the thickness of the adhesive layer S are
It has been a big problem that hinders the thinning of the package. Furthermore, the polyimide tape used here has hygroscopicity, which causes a decrease in reliability of the semiconductor device. Also,
It is expensive, and this is also a problem that prevents cost reduction.

Furthermore, since the heat dissipation plate is arranged on the lower side, there is a problem that the distance between the mounting board and the heat dissipation plate is narrow and the heat dissipation effect is not good.

[0010]

As described above, in the conventional lead frame, the heat dissipation plate and the lead frame main body are connected to each other by the polyimide tape. But,
There is a problem that it causes a decrease in wire bonding property to the tip of the inner lead. Moreover, the heat dissipation is not sufficient, and the use of the polyimide tape causes a decrease in reliability and a rise in product price.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device which has a good heat dissipation effect, is inexpensive, and has high reliability.

[0012]

Therefore, in the present invention, a lead frame main body portion having a plurality of inner leads and outer leads extending from the inner leads, and an inner lead tip portion of the lead frame main body portion are joined together. And a semiconductor element mounting portion, which is made of aluminum or an alloy containing aluminum as a main component and has at least an aluminum oxide coating film formed in a region to be bonded, and is joined to the tip of the inner lead via an adhesive layer, and the semiconductor element. A semiconductor element mounted on the surface of the mounting portion and electrically connected to the inner leads of the lead frame main body portion and a periphery of the semiconductor element so as to expose at least a part of the back surface of the semiconductor element mounting portion. And a sealing resin for stopping.

Desirably, the front surface and the back surface of the semiconductor element mounting portion are covered with an aluminum oxide film.

Preferably, the semiconductor element mounting portion has a recess whose size is such that the semiconductor element mounting region on the surface corresponds to the semiconductor element, and at least the inner wall of the recess is covered with an aluminum oxide film.

According to a second aspect of the present invention, at least an oxide is formed in a lead frame main body portion having a plurality of inner leads and outer leads extending from the inner leads, and at least a region of the lead frame main body portion joined to the inner leads. A semiconductor element mounting part made of aluminum or an alloy containing aluminum as a main component, which is formed with an aluminum coating and has a recess formed in the semiconductor element mounting region; and the semiconductor element mounting part is mounted on a recessed surface of the semiconductor element mounting part, A semiconductor device electrically connected to the lead frame main body; and a sealing resin that seals around the semiconductor device so as to expose at least a part of the back surface of the semiconductor device mounting portion, Extend the inner lead tips of the lead frame body to the recess to connect the semiconductor element. It is directly bonded to.

According to a third aspect of the present invention, a lead frame main body portion having a plurality of inner leads and outer leads extending from the inner leads is formed and is made of aluminum or an alloy containing aluminum as a main component. A semiconductor element mounting portion is formed by forming at least an aluminum oxide coating on a region of the frame body portion to be joined to the inner lead distal end portion, and the inner lead distal end portion is further formed on the surface of the semiconductor element mounting portion via an adhesive layer. After mounting the semiconductor element on the surface of the semiconductor element mounting portion and electrically connecting the element to the inner lead of the lead frame body, at least a part of the back surface of the semiconductor element mounting portion is exposed. It is characterized in that the periphery of the semiconductor element is sealed so that the semiconductor element is sealed.

[0017]

According to the above structure, it is possible to provide a semiconductor device which is extremely thin and has good heat dissipation. That is,
Since a part of the heat sink whose surface is insulated is exposed from the encapsulating resin, the heat dissipation effect is extremely good, and the polyimide tape that causes the decrease in reliability and the price increase should be used. It is possible to form a lead frame having good heat dissipation.

Further, a stable oxide film is easily formed on aluminum, and the insulation with the tip of the inner lead is ensured. Therefore, even if the adhesive layer as the connection medium is made as thin as possible, the insulation can be secured.

Furthermore, aluminum is light in weight, so that reliable mounting can be performed without causing bending even in the molding process.

Desirably, since a recess is formed in the heat sink and the semiconductor element is placed in this recess, the tip of the thin inner lead is well supported and the surface of the heat sink is insulated. The electrical insulation is also kept very good.

Furthermore, in the second aspect of the present invention, a recess is formed in the heat dissipation plate, a semiconductor element is placed in this recess, and the tip of the inner lead extending up to the semiconductor element is directly bonded to the semiconductor element. Since the electrical connection is achieved, the tips of the thin inner leads are well supported, and the surface of the heat sink is insulated, so that the electrical insulation is maintained very well. Furthermore, since heat dissipation is achieved from all surfaces other than the surface of the semiconductor element, heat dissipation efficiency is extremely good. Further, since it is sufficient to perform resin sealing only on the mounting surface side of the semiconductor element, it is possible to reduce the thickness. In addition, by mounting so that the exposed portion of the heat sink is on the upper side of the mounting board, it is possible to bring the heat sink into contact with a larger amount of air than in the case of the conventional example shown in FIG. Can be good.

According to the third aspect of the present invention, it is possible to position the semiconductor element and the lead frame with high accuracy, and it is possible to provide a semiconductor device having good heat dissipation and high reliability.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention.

This semiconductor device comprises a lead frame, a lead frame body having inner leads 1 and outer leads 3, and a semiconductor element mounting portion 2 made of an aluminum plate having an aluminum oxide layer 2S formed on the front and back surfaces. And the back side of the semiconductor element mounting portion is exposed from the sealing resin. The lead frame body has a plurality of inner leads 1 whose tips are joined on the aluminum oxide layer 2S and which extend radially.
And an outer lead 3 that is integrally formed by extending to each inner lead. The inner lead tip 1
The semiconductor element mounting portion 2 and the semiconductor element mounting portion 2 are bonded via an insulating adhesive 4. Then, the semiconductor chip 5 is fixed to the surface of the semiconductor element mounting portion 2 of the lead frame, the semiconductor chip 5 and the inner lead 1 are joined by the bonding wire 6, and the outside is sealed by the sealing resin 9. .

Next, a method of manufacturing this semiconductor device will be described.

First, a strip-shaped material made of a copper alloy is processed by a stamping method to form a lead frame main body portion having inner leads 1, outer leads 3 and tie bars 8.

Then, the aluminum plate is stamped to oxidize the front and back surfaces of the semiconductor element mounting portion 2 to form an aluminum oxide layer 2S.

Then, the tip ends of the inner leads 1 of the lead frame body are fixed on the aluminum oxide layer 2S with an adhesive S to obtain a lead frame as shown in FIGS. 2 (a) and 2 (b). .

Further, the semiconductor chip 5 is fixed on the semiconductor element mounting portion 2 and is connected to the inner leads 1 of the lead frame main body portion and the bonding pads of the semiconductor chip 5 through the wires 6 by the wire bonding method.

Then, after a molding step, a frame body cutting step, and a molding step of folding the outer leads into a desired shape, the semiconductor device as shown in FIG. 1 is completed.

Since the heat dissipation plate of this lead frame is exposed from the encapsulating resin, the heat dissipation performance is extremely good, and the lead frame is a connection medium between the lead frame body and the semiconductor element mounting portion that also serves as the heat dissipation plate. Even if the adhesive layer is made as thin as possible,
Since the aluminum oxide film 2S maintains a reliable insulation,
It is possible to always maintain the distance between the lead frame main body and the semiconductor element mounting portion which is the heat dissipation plate, and ensure insulation.

Further, since the adhesive layer is formed to be extremely thin, the positional accuracy of the tips of the inner leads can be kept higher, and the bonding property is improved.

Further, since the semiconductor element mounting portion is lightweight, it is possible to perform reliable thin mounting without causing any bending in the molding process or the like.

Further, since the inner lead of the lead frame main body formed by punching is formed shorter than a normal lead frame, the deformation can be less,
Also, when mounting the chip on the lead frame, the inner lead tip is correct depending on the heat history in the wire bonding process between the chip bonding pad and the inner lead tip and the heat history in the molding process. Since it is fixed at the position, it is possible to obtain a highly reliable semiconductor device without causing connection failure.

Furthermore, the semiconductor device thus formed is not only subjected to the mounting process but also after completion.
The heat dissipation is extremely good, and the tip of the inner lead is fixed at the correct position on the heat dissipation plate, so that the reliability is extremely high.

Although the aluminum oxide film is formed by oxidizing the entire surface of the semiconductor element mounting portion in the above embodiment, the aluminum oxide film may be formed only on the peripheral portion.

Further, although the semiconductor element mounting portion is formed of aluminum in the above embodiment, an alloy containing aluminum may be used as long as the aluminum oxide film can be easily formed on the surface.

Next, a second embodiment of the present invention will be described.

In this semiconductor device, as shown in FIG. 3, a recess 10 is formed in the semiconductor element mounting region of the semiconductor element mounting portion as the heat sink 2, and the semiconductor element 5 is mounted in the recess 10 to control the position. In addition, the electrical connection between the lead frame main body and the semiconductor element is achieved by direct bonding to further reduce the thickness and enhance the protection of the semiconductor element. Other parts were formed in the same manner as in the first embodiment. Here, the entire surface including the inner wall of the recess 10 is covered with an aluminum oxide film, the inner lead 1 is fixed to this surface through an adhesive layer, and the inner lead tip 1S is extended directly onto the bonding pad of the semiconductor element. It is designed to be joined.

According to this structure, since the position of the semiconductor element is determined by the concave portion, the mounting workability is good and highly accurate positioning can be achieved. Further, by adjusting the depth of the concave portion, the semiconductor element can be adjusted. Since the position of the bonding pad of No. 5 and the height level of the tip of the inner lead can be made to be the same, the protection of the semiconductor element is extremely high and the heat radiation from the back surface side can be satisfactorily achieved. It is possible to obtain a semiconductor device having extremely high reliability.

The depth of the recess does not necessarily have to be approximately the same as the thickness of the semiconductor element and can be changed as appropriate.

The recess need not be formed so as to match the outer shape of the semiconductor element, and may be formed in the shape of a groove.

Furthermore, in the above embodiment, the sealing resin 9 is formed on both sides of the lead frame and the semiconductor element.
As shown in FIG. 4, the sealing resin 9 may be disposed only on the back surface side of the semiconductor element 5, and the protective film 12 may be applied to the front surface side, that is, the bonding surface side.

Further, as shown in FIG. 5, only the bonding surface side, that is, the front surface side of the semiconductor element may be resin-sealed, and the rear surface side, that is, the heat radiating plate side may be exposed as it is. The semiconductor element is well protected and can be made extremely thin.

In the case of the structure shown in FIGS. 4 and 5, the sealing resin is arranged only on one side. Therefore, when it is difficult to perform the usual molding method, the uncured resin is applied to the fiber or the like. It is possible to easily carry out the sealing formation by a method of mounting the impregnated one and hardening it while applying pressure.

[0047]

As described above, according to the present invention, it is possible to provide a semiconductor device having good heat dissipation, low cost and high reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of the same semiconductor device.

FIG. 3 is a diagram showing a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a semiconductor device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a semiconductor device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a conventional semiconductor device.

[Explanation of symbols]

 1 Inner Lead 2 Semiconductor Element Mounting Part 2S Aluminum Oxide Film 3 Outer Lead 4 Insulating Adhesive 5 Semiconductor Chip 6 Bonding Wire 7 Heat Sink 8 Tie Bar 9 Sealing Resin 10 Recess 12 Protective Film

Claims (5)

[Claims] 1. An aluminum having at least an aluminum oxide film formed on a lead frame main body portion having a plurality of inner leads and outer leads extending therefrom, and at least an area where the lead frame main body portion is joined to the inner lead tip portions. Alternatively, a semiconductor element mounting portion made of an alloy containing aluminum as a main component and bonded to the inner lead tip portion via an adhesive layer, and an inner portion of the lead frame body portion mounted on the surface of the semiconductor element mounting portion. A semiconductor element electrically connected to the lead; and a sealing resin that seals around the semiconductor element so as to expose at least a part of the back surface of the semiconductor element mounting portion. Semiconductor device. 2. The semiconductor device according to claim 1, wherein the front surface and the back surface of the semiconductor element mounting portion are covered with an aluminum oxide film. 3. The semiconductor element mounting portion is provided with a recess having a size such that a semiconductor element mounting region on the surface corresponds to the semiconductor element, and at least the inner wall of the recess is covered with an aluminum oxide film. The semiconductor device according to claim 1. 4. A semiconductor device comprising a lead frame main body portion having a plurality of inner leads and outer leads extending therefrom, and at least an aluminum oxide film formed on a region of the lead frame main body portion to be joined to the inner leads. A semiconductor element mounting portion made of aluminum or an alloy containing aluminum as a main component, in which a concave portion is formed in the element mounting area, and mounted on the surface of the concave portion of the semiconductor element mounting portion to electrically connect the lead frame main body portion. And a sealing resin that seals around the semiconductor element so as to expose at least a part of the back surface of the semiconductor element mounting portion, and the inner lead tip portion of the lead frame main body is ,
A semiconductor device, wherein the semiconductor device extends to the recess and is directly joined to a connection region of the semiconductor element. 5. A lead frame main body forming step of forming a lead frame main body including a plurality of inner leads and outer leads extending therefrom; and the lead frame main body made of aluminum or an alloy containing aluminum as a main component. Section for forming a semiconductor element mounting section in which at least an aluminum oxide film is formed in a region to be joined to the tip of the inner lead of the inner section, and a step for forming a semiconductor element mounting section A lead frame assembling step of joining the lead tips, a connecting step of placing a semiconductor element on the surface of the semiconductor element mounting portion, and electrically connecting this element to an inner lead of the lead frame main body; The semiconductor element so that at least a part of the back surface of the mounting portion is exposed. And a resin encapsulation step of encapsulating the periphery of the semiconductor device.