JPH11233692A - Resin encapsulated semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid short-circuiting between leads and semiconductor element mounting part. SOLUTION: A heat sink 12 has a rectangular element mounting face 14 with a first insulator 42 disused at the edge of the short side. The first insulator 42 is composed of a double-sided adhesive tape to adhere the heat sink 12 to leads 18 with an insulation gap between the top end of the lead 18 and the heat sink 12. A second insulator 44 composed of a single-sided adhesive tape is adhered to the ends of the leads 18 around a semiconductor element 16 which is connected to threads 18 via wires 22. The second insulator 44 has a thickness with a gap formed with the heat sink and is provided over a part, corresponding to the connection positions of the wires 22 at least from the top ends of the leads 18 to prevent the direct contact of the leads 18 to the heat sink 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing resin type semiconductor device, and more particularly to a semiconductor device using a heat sink for a mounting portion of a semiconductor element. The present invention relates to a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art As a conventional semiconductor device, a semiconductor element fixed to a heat sink is arranged in a space formed in a lead frame, and when a lead of the lead frame and a semiconductor element are connected by a wire, the lead frame and the semiconductor element are connected. In order to prevent displacement of the heat sink, there is known a structure in which an insulator having an adhesive on both sides is disposed around the semiconductor element on the semiconductor element mounting surface of the heat sink, and the heat sink and the lead frame are bonded. (For example, JP-A-6-5746). However, in this semiconductor device, when the wire is pressed into contact with the lead, the insulator existing under the lead is deformed, the wire cannot be connected to the lead well, and connection failure is likely to occur.

Accordingly, the present applicant has proposed a resin-sealed semiconductor device with a heat sink in which an insulator is provided only at the outer peripheral edge of the heat sink without providing an insulator at a portion where the tip of the lead is located. (JP-A-6-53390). FIGS. 5A and 5B show such a semiconductor device with a heat sink, wherein FIG. 5A is a cross-sectional view, and FIG. 5B is a sectional view taken along line AA of FIG.

In FIG. 5, a semiconductor device 10 has a convex heat sink 12 made of copper, a copper alloy, aluminum, an aluminum alloy, or the like having good thermal conductivity, and a central portion of an element mounting surface 14 of the heat sink 12. The semiconductor element 16 is fixed to the substrate. The semiconductor element 16 has a space 20 formed by a plurality of leads 18 provided on a lead frame.
And a terminal portion (not shown) is electrically connected to the tip of the lead 18 by a wire 22. Further, a frame-shaped insulator 24 is arranged on the outer peripheral edge of the element mounting surface 14 of the heat sink 12 as clearly shown in FIG.

The insulator 24 is provided with an adhesive (not shown) on both sides.
The heat sink 12 is bonded to the lead 18 to prevent the displacement between the lead 18 and the semiconductor element 16 and, as shown in FIG. An insulating space 26 is formed between them. The element mounting surface 14 and the side of the heat sink 12 are connected to the lead 18, the wire 22, and the semiconductor element 1.
The package 6 is packaged with a sealing resin 28.
By the way, the semiconductor element 16 and the lead 18 are connected to the wire 22
The connection is performed by pressing the tip of the lead 18 against the heat sink 12 by the lead press of the bonding apparatus. In the current bonding apparatus, when pressing the lead 18 against the heat sink 12 by pressing the lead, the distance L from the tip of the lead 18 to the insulator 24 is required to be 2.5 mm or more, and the package becomes large. For this reason, the present applicant has proposed a resin-sealed semiconductor device as shown in FIG.

In the semiconductor device 30 shown in FIG. 6, the element mounting surface 14 of the convex heat sink 12 is formed in a rectangular shape. In the semiconductor device 30, as shown in FIG. 2B, the insulator 24 is provided only on the short side edge of the rectangular element mounting surface 14, and the insulation is provided on the long side. The lead 18 can be shortened without providing an object, thereby reducing the size of the package.

[0007]

However, in the conventional semiconductor device 30 shown in FIG. 6, the heat sink 12 and the lead 18 may be in contact with each other for the following reasons.

The insulator 24 forming the insulating gap 26 between the heat sink 12 and the lead 18 has a thickness of 75 μm.
m. On the other hand, when the heat sink 12 is formed of, for example, a pure copper plate, the thickness of the copper plate has a manufacturing error of about ± 30 μm. Then, the lead 18 is pressed against the heat sink 18 by a lead holder, and the wire 22
After the lead is connected, the lead retainer is retracted from the lead 18 so that the lead 18 returns to the initial position by springback due to the elasticity of the lead 18, but an insulator forming an insulating gap is disposed on the long side. In some cases, the lead 18 on the long side may not return completely to the initial position.
8 may contact the heat sink 12.

In the conventional resin-encapsulated semiconductor device, the lead 18 and the semiconductor element 16 are connected via a wire 22 and then disposed in a cavity of a mold and filled with a sealing resin 28. At the time of sealing, the leads 18 may be deformed by the flow of the sealing resin 28, and the leads 18 may come into contact with each other to cause an electrical short circuit between the leads 18.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to prevent a short circuit between a lead and a semiconductor element mounting portion.

It is another object of the present invention to prevent leads from being deformed due to the flow of sealing resin, thereby preventing short circuits between the leads.

[0012]

In order to achieve the above object, a semiconductor device with a heat sink according to the present invention comprises a plurality of leads, one of which is extended toward a central region, and a non-wiring of the leads. A semiconductor element which is located in the central area, which is an area, and which is electrically connected to the lead via a wire; and an element mounting surface on which the semiconductor element is mounted has a rectangular shape larger than the central area. The formed semiconductor element mounting portion and a first insulator provided at a short side edge of the element mounting surface and forming an insulating gap between the lead and the semiconductor element mounting portion faced each other. A second insulator provided on one of the element mounting surface and the lead and forming a gap between the lead or the element mounting surface, at least the semiconductor element;
The semiconductor device is characterized by having a portion overlapping the element mounting surface of the wire and the lead, and a resin sealing the element mounting surface of the semiconductor element mounting portion.

According to the present invention having the above-described structure, the gap between the semiconductor element mounting portion and the lead can be obtained by interposing the second insulator between the element mounting surface of the semiconductor element mounting portion and the lead. Can be reduced, the semiconductor element mounting portion and the lead can be prevented from directly contacting each other, and a short circuit between them can be prevented. Since a gap is formed between the second insulator and the lead or the semiconductor element mounting portion, it is possible to reliably and satisfactorily fill the sealing resin between the lead and the semiconductor element mounting portion. For example, even when moisture invades from between the sealing resin and the lead, and a metal element constituting the lead dissolves in the moisture to cause migration, the lead and the semiconductor element mounting portion may Since the sealing resin interposed therebetween prevents movement of the metal element, a short circuit between the lead and the semiconductor element mounting portion can be prevented.

When the semiconductor element mounting portion is a convex heat sink, heat generated from the semiconductor element can be efficiently radiated into the atmosphere by exposing a part of the heat sink from the sealing resin. Operating characteristics can be improved.

If the second insulator is formed thinner than the first insulator, a gap between the lead or the semiconductor element mounting portion and the second insulator can be easily formed. And
When the second insulator is bonded to the element mounting surface or the lead with a thermosetting adhesive, the adhesive of the second insulator is thermally cured when the adhesive fixing the semiconductor element to the element mounting surface is thermally cured. Can be cured and the process can be simplified, and when the wire is pressed against the lead because the elasticity of the adhesive is lost, the connection of the wire can be made well by eliminating the cushioning effect of the adhesive. Can be.

Furthermore, by providing the insulator at least from a portion corresponding to the wire connection position of the lead from the tip of the lead, the lead does not completely return to the initial position when the lead is retracted after the wire connection. Even if such is the case, a short circuit between the lead and the semiconductor element mounting portion can be reliably prevented. Further, by providing the second insulator on the lead side, the contact area between the lead and the sealing resin that is not very good with the sealing resin can be reduced, and the adhesion between the sealing resin and the lead can be improved. can do. Then, by connecting the plurality of leads to each other with the second insulator, it is possible to reliably prevent the leads from being deformed by the flow of the sealing resin and short-circuiting between the leads. In addition, the second insulator may be provided on the entire periphery of the semiconductor element. However, by providing the second insulator only on the short side of the element mounting surface on which the lead that easily contacts the heat sink is arranged.
The second insulator can be easily attached, and the amount of the insulator used can be reduced.

[0017] By setting the thickness of the second insulator to 25 µm or less, even when the second insulator is formed of a resin such as polyimide, the second insulator when the wire is pressed against the lead is formed. The amount of deformation of itself can be reduced, and a wire can be connected to the lead satisfactorily. Further, for example, when the second insulator is formed of polyimide or the like having a high withstand voltage, the withstand voltage of the second insulator is set to 1 kV or more, so that the thickness of the second insulator is significantly thinner than 25 μm. And the connection of the wires to the leads can be further improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a resin-sealed semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are given to the portions corresponding to the portions described in the above-described related art, and the description thereof is omitted.

FIG. 1 is an explanatory view of a resin-sealed semiconductor device according to an embodiment of the present invention, in which a sealing resin is omitted.
FIG. 3 is a cross-sectional view taken along line CC of FIG. 1, and FIG. 3 is a cross-sectional view taken along line DD of FIG.

In these figures, a semiconductor device 40 is
An element mounting surface 14 of a heat sink 12 as a semiconductor element mounting portion is formed in a rectangular shape, and a semiconductor element 16 is bonded to a central portion of the element mounting surface 14. A first insulator 42 is provided at both short side edges of the element arrangement surface 14. The first insulator 42 is formed, for example, by applying an adhesive to both surfaces of a base film made of polyimide having a thickness of 75 μm to a thickness of 20 μm.
Made of so-called double-sided adhesive tape
While bonding the heat sink 12 and the lead 18,
An insulating gap 26 is formed between the tip of the lead 18 and the heat sink 12 (see FIG. 2).

One end of the lead 18 is formed to extend toward the central region of the lead frame. The semiconductor element 16 is arranged in the space 20 which is a non-wiring area of the lead 18 in the central area. A frame-shaped second insulator 44 is arranged between the lead 18 around the semiconductor element 16 and the element mounting surface 14. In the case of this embodiment, the second insulator 44 is constituted by a so-called single-sided adhesive tape in which an adhesive 48 is applied to one side of a polyimide film 46 having a thickness of 25 μm to a thickness of about 20 μm as shown in FIG. The leads 18 are adhered to the tips of the leads 18 and interconnect the plurality of leads 18. Then, a gap 50 is formed between the second insulator 44 and the element mounting surface 14 in a state of being bonded to the lead 18. Also, the second insulator 44
Are provided at a portion corresponding to a position where the wire 22 of the lead 18 is connected from the tip of the lead 18 or more.
After the lead 8 is pressed against the heat sink 12 by the lead holder (not shown) when the wire 22 is connected, even if the lead holder does not return to the initial position when the lead holder is retracted, the contact between the lead 18 and the heat sink 12 is ensured. It can be prevented.

The adhesive 48 is desirably a thermosetting material, and is hardened by heat to harden the elasticity.
Bonding of the wire 22 to the lead 18 can be performed reliably and well. Moreover, the second insulator 44
Since the adhesive 48 is provided only on one side, the buffering effect of the second insulator 44 can be further reduced. The adhesive 48 is made of, for example, the same epoxy resin as the adhesive bonding the semiconductor element 16 to the heat sink 12, and is simultaneously cured in a die bonding curing step of curing the adhesive bonding the semiconductor element 16. It is desirable to make it possible to simplify the process.

Further, the adhesive 48 generates a gas component when cured by heat, that is, a material with little so-called outgas,
In particular, a material that does not emit gas components at the time of wire bonding exposed to a high temperature of about 250 ° C. is desirable. By using the adhesive 48 having a small outgas, it is possible to prevent the outgas from contaminating the leads 18 and making it difficult to connect the wire 22, thereby improving the quality of bonding. In the case of this embodiment, the adhesive 48 has a weight loss of 0.3% after curing with respect to the weight before curing. Incidentally, the adhesive of the conventional double-sided pressure-sensitive adhesive tape generally used in the semiconductor field has a weight loss after curing of about 3.1% of the weight before curing.

It is desirable that the adhesive 48 has good adhesion to the sealing resin 28. In the case of this embodiment, since the adhesive 48 uses an epoxy-based resin as the sealing resin 28, an adhesive made of an epoxy-based resin is used, but the adhesive 48 is changed according to the type of the sealing resin 28. May be. By using the adhesive 48 having good adhesion to the sealing resin 28, it is possible to prevent a crack from being generated between the sealing resin 28 and the lead 18 and peeling, thereby improving the reliability of the semiconductor device. can do. The adhesive 48 of the embodiment is made of Mo, which is a standard for semiconductor packages in the United States.
No peeling occurred even at level 1 of the issue Sensitive Test.

That is, the semiconductor device 4 according to the embodiment
After drying 0 at 125 ° C. for 24 hours or more, 8
After standing in a thermo-hygrostat at 5 ° C. and a relative humidity of 85% for 168 hours, heating at 220 ° C. for 10 seconds was repeated three times in an IR reflow furnace, which was cut and observed with a microscope. It was confirmed that.

As described above, in the semiconductor device 40 according to the embodiment, the variation in the gap between the lead 18 and the heat sink 12 is reduced by disposing the second insulator 44 at the tip of the lead 18. When the lead holder that presses the lead 18 against the heat sink 12 is retracted, even if the lead 18 does not completely return due to the action of the springback, the lead 1
8 and the heat sink 12 can be reliably prevented from being short-circuited. Furthermore, in the embodiment, each lead 18
Are connected to each other by the second insulator 44, so that the sealing resin 28 is disposed in the mold cavity.
Is filled in the cavity, the flow of the sealing resin 28 deforms the leads 18 so that the leads 18 come into contact with each other.
A short circuit between them can be prevented.

Furthermore, the gap 50 is formed between the second insulator 44 and the heat sink 12, so that the lead 1
And the heat sink 12 can be easily and reliably filled with the sealing resin.
Separation between the lead 18 and the heat sink 12, even if moisture is infiltrated and the metal element forming the lead 18 is dissolved in the water and migration occurs. Since the interposed sealing resin 28 prevents the movement of the metal element, a short circuit between the lead 18 and the heat sink 12 can be prevented. In the above embodiment, since the convex heat sink 12 is used as the semiconductor element mounting portion and a part thereof is exposed from the sealing resin 28, the heat generated from the semiconductor element 16 is efficiently radiated into the atmosphere. And the operating characteristics of the semiconductor element 16 can be improved.

In the above-described embodiment, the case where the second insulator 44 is provided on the lead 18 has been described. However, the second insulator 44 may be provided on the element placement surface 14 side of the heat sink 12. In the above embodiment, the second insulator 4
Although the case where 4 is a polyimide having a thickness of 25 μm has been described, another resin or ceramic may be used. The polyimide having a thickness of 25 μm used as the second insulator 44 in the embodiment has a withstand voltage of about 6.8 kV, which is too high for a general semiconductor device. The thickness may satisfy required withstand voltage, for example, 1 kV withstand voltage. Further, in the above embodiment, the lead 18 on the short side of the heat sink 12 is used.
Although the case where the second insulator 44 is provided has been described above, the second insulator 44 may be provided only on the lead 18 on the long side. Further, in the above embodiment, the case where the semiconductor element mounting portion is the convex heat sink 12 has been described, but the semiconductor element mounting portion may be a multilayer wiring board or the like.

[0029]

As described above, according to the present invention, since the second insulator is interposed between the element mounting surface of the semiconductor element mounting portion and the lead, the semiconductor element mounting portion has While reducing the variation in the gap with the lead,
Direct contact between the semiconductor element mounting portion and the lead can be prevented, and a short circuit between them can be prevented. In addition, since a gap is formed between the second insulator and the lead or the heat sink, the sealing resin can be reliably and satisfactorily filled between the lead and the semiconductor element mounting portion. Even if moisture invades from between the resin and the lead and the metal elements that make up the lead melt out into the water and cause migration, the sealing resin blocks the metal element, so the lead and the semiconductor element are mounted. It is possible to prevent a short circuit with the unit.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a semiconductor device according to an embodiment of the present invention, in which a sealing resin is omitted.

FIG. 2 is a sectional view taken along line CC of FIG. 1;

FIG. 3 is a cross-sectional view taken along line DD of FIG.

FIG. 4 is a detailed sectional view of a second insulator according to the embodiment.

FIG. 5 is an explanatory diagram illustrating an example of a conventional semiconductor device.

FIG. 6 is an explanatory diagram of another example of a conventional semiconductor device.

[Explanation of symbols]

 12 semiconductor element mounting portion (heat sink) 14 element mounting surface 16 semiconductor element 18 lead 20 non-wiring region (space portion) 22 wire 26 insulating gap 42 first insulator 44 second insulator 48 adhesive 50 gap

Claims (10)

[Claims] 1. A plurality of leads, one of which extends toward a central region, is located in the central region, which is a non-wiring region of the lead, and is electrically connected to the lead via a wire. A semiconductor element mounting part in which an element mounting surface on which the semiconductor element is mounted is formed in a rectangular shape larger than the central region; and a short side edge of the element mounting surface. Forming an insulating gap between the lead and the semiconductor element mounting portion by
And a second insulator that is provided on one of the element mounting surface and the lead facing each other and forms a gap between the lead and the element mounting surface. A resin-encapsulated semiconductor device comprising: a semiconductor element, a portion of the wire, the lead overlapping the element mounting surface, and a resin sealing the element mounting surface of the semiconductor element mounting portion. . 2. The resin-encapsulated semiconductor device according to claim 1, wherein the semiconductor element mounting portion is a convex heat sink. 3. The resin-encapsulated semiconductor device according to claim 1, wherein the second insulator is formed thinner than the first insulator. 4. The resin according to claim 1, wherein the second insulator is bonded to the element mounting surface or the lead with a thermosetting adhesive. Sealed semiconductor device. 5. The apparatus according to claim 1, wherein the second insulator is provided at least from a tip of the lead to a portion corresponding to a wire connection position of the lead. Resin-sealed semiconductor device. 6. The resin-encapsulated semiconductor device according to claim 1, wherein the second insulator is provided on the lead side. 7. The resin-encapsulated semiconductor device according to claim 6, wherein said second insulator interconnects a plurality of said leads. 8. The resin-encapsulated semiconductor device according to claim 1, wherein the second insulator is provided only along a long side of the element mounting surface. 9. The resin-sealed semiconductor device according to claim 1, wherein said second insulator has a thickness of 25 μm or less. 10. The second insulator has a withstand voltage of 1 kV.
The resin-sealed semiconductor device according to claim 1, wherein: