JP2001024110A - Resin sealed semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short circuit between a heat-radiation plate and an inner lead, and effectively transfer heat from the inner lead, related to a resin sealed semiconductor device incorporated a heat radiation plate formed by injecting a resin with a die. SOLUTION: A lead frame 3 where a semiconductor element 2 is mounted is provided on one surface of a heat radiation plate 10. The heat radiation plate 10, semiconductor element 2, and lead frame 3 are sealed with a resin 5. Related to the heat radiation plate 10, an outer edge (heat dispersion part) 10b is bent in the opposite direction on the side where the lead frame 3 is arranged. Thus, the resin flows downward to the heat radiation plate 10 when the resin is injected into a die, so the tilt and rise of the heat radiation plate 10 are prevented at resin molding. Since the interval between the inner lead 3b and the heat radiation plate 10 is larger, the contact between them is easily prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a resin-sealed semiconductor device having a built-in heat sink (heat spreader).

[0002]

2. Description of the Related Art In recent years, with the spread of chips in which a logic circuit and a power element are mixed and an increase in power consumption due to an increase in the scale of a logic circuit, it is desired to reduce the thermal resistance of a multi-pin type mold package. For this purpose, conventionally, when performing resin molding of a semiconductor device, a heat sink (heat spreader) made of a metal such as Al or Cu having a good thermal conductivity is thrown into a mold, and the resin is molded simultaneously with the resin. There is a sealed semiconductor device. This resin-sealed semiconductor device will be described with reference to FIGS. 5A is a plan view showing a schematic configuration of a resin-sealed semiconductor device, FIG. 5B is a cross-sectional view taken along the line BB of FIG. 5A, and FIG. 6 (b) is a cross-sectional view taken along the line CC of FIG. 6 (a). In FIG. 5A, the wires 6 connecting the semiconductor chip 2 and the inner leads 3b are omitted.

As shown in FIGS. 5A and 5B, this type of resin-sealed semiconductor device 100 is generally a power MOS type.
A semiconductor chip 2 including an FET and the like, a lead frame 3 having an island portion 3a on which the semiconductor chip 2 is mounted, and a heat radiating plate 1 for promoting heat radiation of the semiconductor chip 2
0 ′ is sealed with a mold resin 5. It is formed by injecting and filling a resin 5 in a state where the semiconductor chip 2, the lead frame 3, and the heat sink 10 'are arranged in a mold.

In the semiconductor device 100 incorporating such a heat sink 10 ', the heat sink 10' and the lead frame 3 are separate and independent components, and the heat sink 10 'is not fixed to other components. It is called a “drop-in type” heat spreader built-in type package because it is simply thrown into the molding die 7.

As shown in FIGS. 6 (a) and 6 (b), the heat radiating plate 10 'has a heat transfer portion 1 to which heat generated from the semiconductor chip 2 is transmitted through the island portion 3a of the lead frame 3.
0a ', a heat diffusion portion 10b' for spreading the heat over the entire package to lower the thermal resistance, and a projecting portion 10c 'for supporting the heat sink so as not to be exposed to the outside during resin molding. Normally, as shown in FIG.
By setting the island portion 3a of
Contact between inner lead 3b and heat sink 10 '(short)
Has been prevented.

[0006]

According to the above-mentioned manufacturing method, a resin-encapsulated semiconductor device can be simply and inexpensively manufactured, but has the following problems. That is, when the resin is injected into the mold, the heat radiating plate 10 'is not fixed. Therefore, if the heat radiating plate 10' is extremely inclined during the resin molding, the inner lead 3b and the heat radiating plate 10 'come into contact with each other to cause a short circuit. May be caused. When the space below the lead frame 3 is increased in order to prevent the inner lead 3b from contacting the heat sink 10 ', as shown in FIG.
There has been a problem that the gap between 0 'and the island portion 3a is increased, the thermal resistance is increased, and the heat dissipation is deteriorated.

In order to prevent such a problem, Japanese Patent Application Laid-Open No.
In the semiconductor device described in Japanese Unexamined Patent Publication No. 0016, a concave portion is provided in a resin molding die, and a heat radiating plate is fitted into the concave portion to prevent displacement of the heat radiating plate during resin injection. However, this method cannot prevent the heat sink from floating in the mold, and there is a possibility that the heat sink contacts the inner lead to cause a short circuit. In addition, there is a problem in that a cut is formed in the mold, so that the mold is hardly separated from the mold.

On the other hand, in the semiconductor device described in Japanese Patent Application Laid-Open No. 61-194861, the heat radiating plate is fixed by providing a projecting portion on the island portion on which the semiconductor chip is arranged and the heat radiating plate below the island portion. However, in this method, there is a problem that the shape of the inner lead is largely restricted because the protrusion is provided around the island portion.

In view of the above, the present invention is directed to a resin-sealed semiconductor device having a built-in heat sink formed by injecting a resin using a mold, and a short circuit between the heat sink and the inner lead. It is an object of the present invention to prevent the occurrence of heat and effectively conduct heat transfer from the inner lead.

[0010]

SUMMARY OF THE INVENTION The present invention focuses on the point that the above-described problem occurs because the behavior of the resin at the time of injecting the resin into the mold is unstable because the heat radiation plate has a flat plate shape. In the invention according to the first aspect, the heat radiating plate (10) is characterized in that the outer edge portion (10b) is bent in a direction opposite to the side where the lead frame (3) is arranged. I have.

By forming the heat radiating plate (10) in such a shape, the behavior of the heat radiating plate (10) during resin injection can be positively controlled. That is, the flow of the resin acts downward with respect to the radiator plate (10), so that the resin plate can be prevented from tilting or rising during resin molding. Also, the inner lead (3b) and the heat sink (1
0), the contact therebetween can be easily prevented.

According to the second aspect of the present invention, the heat radiating plate (10) is provided with a protruding portion (10c) protruding in a direction opposite to the side where the lead frame (3) is disposed, and the outer edge portion (10b).
Is characterized in that the amount of bending is smaller than the amount of protrusion of the protrusion (10c).

The reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiments described later.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 is a sectional view of a resin-sealed semiconductor device (hereinafter, referred to as a semiconductor device) 1 according to an embodiment of the present invention. The semiconductor device 1 according to the present embodiment has a QFP (Quad
Flat package), which is used, for example, in a power semiconductor device such as a driver IC or a power supply IC used in an engine control ECU, an ABS ECU, or the like in an automobile.

Here, the semiconductor device 1 shown in FIG. 1 is different from the semiconductor device 100 shown in FIG. 5 only in the configuration of the heat radiating plate. The same reference numerals are given. FIG. 2A is a plan view of the heat sink 10, and FIG.
It is A sectional drawing. The semiconductor device 1 has a planar rectangular shape.

The semiconductor device 1 houses a heat sink 10, a lead frame 3 arranged on the upper surface of the heat sink 10, and a semiconductor chip (semiconductor element) 2, and these members are made of, for example, epoxy resin. It is sealed and integrated in a thin rectangular shape with a mold resin 5.

The lead frame 3 includes an island portion 3a on which the semiconductor chip 2 is mounted, and a plurality of lead portions 3 drawn out of the mold resin 5 from around the island portion 3a.
b, 3c. Leads 3b, 3c
Is composed of an inner lead 3b which is a part located in the mold resin 5, and an outer lead 3c which is a part drawn out of the mold resin 5. The island 3
a is connected to a portion (not shown) of the lead frame 3 outside the mold resin 5.

The semiconductor chip 2 is mounted on the island portion 3a of the lead frame 3 via a conductive resin such as Ag paste or an adhesive (not shown) such as solder. The semiconductor chip 2 includes the inner leads 3b
To the lead portion 3b,
An electric signal can be exchanged between the semiconductor chip 2 and the outside via the wires 3c and the wires 6.

The heat radiating plate 10 is made of a material having excellent thermal conductivity such as an aluminum alloy or a copper alloy having a thickness of about 0.1 to 0.5 mm. The heat sink 10
As shown in FIGS. 2A and 2B, the heat generated from the semiconductor chip 2 is transmitted through the island portion 3a of the lead frame 3, and the heat transfer portion 10a spreads the heat over the entire package to reduce the thermal resistance. It is composed of a heat diffusion portion 10b to be lowered, and a protruding portion 10c that supports the heat dissipation plate so as not to be exposed to the outside during resin molding. The heat diffusion portion 10b constitutes an outer edge in the present invention.

The radiator plate 10 is formed by press working or the like. The heat transfer section 10a is formed in a flat plate shape,
0b is formed in a radial shape in order to increase the heat conductivity to the entire package and to enhance the resin filling property below the heat radiating plate 10 at the time of molding the resin. In order to support the lead frame 3 so as not to be exposed, the protrusion is formed in a direction opposite to the side on which the lead frame 3 is disposed (downward in FIGS. 1 and 2B) from the heat transfer portion 10a. In the present embodiment, the amount of protrusion of the protrusion 10c is set to 0.
It is about 5 mm.

As shown in FIGS. 1 and 2B, the heat diffusion portion 10b is bent from the heat transfer portion 10a in a direction opposite to the side on which the lead frame 3 is disposed. At this time, it is necessary to prevent the tip of the heat diffusion unit 10b from being lower than the protrusion 10c. As described above, in the present embodiment, since the protrusion amount of the protrusion 10c is about 0.5 mm, the bending amount of the heat diffusion unit 10b is 0.1 to 0.1 mm from the heat transfer unit 10a.
It is about 0.3 mm.

Next, a method of manufacturing the semiconductor device 1 having the above configuration will be described with reference to FIG. 3 showing a flow of the resin 5 when the resin 5 is injected into the mold 7. In FIG. 3, the wires 6 are omitted. First, the heat sink 10 alone is dropped into a lower mold 7b of a mold (molding mold) 7 heated to a predetermined temperature. Thereafter, the lead frame 3 on which the semiconductor chip 2 is mounted and wire-bonded is set on the lower die 7b by bringing the island portion 3a into contact with the heat transfer portion 10a of the heat sink 10.

Then, the upper mold 7a of the mold 7 is set, and the mold resin 5 is injected and filled in the mold 7 in a softened state to perform resin sealing. First, the mold resin 5 whose viscosity has been reduced by the heat of the mold 7 is injected and filled into the cavity 9 from a gate (injection port) 8 provided in the lower mold 7b of the mold 7. At this time, since the heat diffusion portion 10b of the heat sink 10 of the present embodiment is bent downward, the flow direction of the resin is downward with respect to the heat sink 10 as indicated by the arrow in FIG. After the resin is hardened, surface treatment for soldering the outer leads 3c is performed, and finally, the outer leads 3c are processed into a predetermined shape, thereby completing the semiconductor device 1.

As described above, according to the heat sink of the present embodiment, the behavior of the heat sink during resin injection can be positively controlled. That is, the contact between the radiator plate 10 and the inner lead 3a usually occurs when the radiator plate 10 tilts or rises when the resin is injected into the mold. On the other hand, as in the present embodiment, the heat diffusion portion 10
By bending b downward, as shown in FIG. 3, the flow of the resin in the mold is directed downward with respect to the radiator plate 10, so that even when the resin enters below the radiator plate, the radiator plate is securely placed. A downward force will act on Therefore, in the heat sink of the present embodiment, it is possible to prevent the heat sink from being inclined or rising in the mold as in the case of the conventional flat heat sink.

Even when the heat sink 10 is set in the mold while being inclined for some reason, if the shape is as described above, the protruding portion 10c and the tip of the heat diffusion portion 10b may be in the mold. The movement inside the mold is restricted, and the inclination in the mold can be greatly reduced as compared with the conventional flat heat sink.

The contact (short) between the heat sink 10 and the inner lead 3b is most likely to occur at the tip of the radial heat diffusion portion 10b, but in the present embodiment, the contact goes to the tip of the heat diffusion portion 10b. Therefore, contact between the heat sink 10 and the inner leads 3b can be easily prevented.

Since the thinner the resin of the semiconductor device 1 is, the lower the thermal resistance can be, the lower mold 7b on which the heat radiating plate 10 is disposed is required to be as thin as possible. However, in the case where the resin thickness is reduced, if a short circuit between the inner lead 3b and the inner lead 3b is prevented only by increasing the distance between the island portion 3a and the heat radiating plate 10, the resin thickness below the heat radiating plate 10 becomes small. It is easy to cause molding failure such as unfilling. On the other hand, when the distal end of the heat diffusion portion 10b is bent downward as in the present embodiment, the gap between the island portion 3a and the radiator plate 10 can be reduced. However, a thin portion can be minimized, and unfilled resin can be prevented. Further, it is effective from the viewpoint of reducing the thermal resistance that the distance between the island portion 3a and the heat sink 10 can be reduced.

(Other Embodiments) Note that the heat transfer portion in contact with the island portion of the lead frame is not a flat plate like the heat sink of the above embodiment, but a convex shape as shown in FIG. By combining the downward bending of the portion 10b, it is possible to easily cope with a semiconductor device having a thick resin.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device according to an embodiment.

2A is a plan view of a heat sink in the semiconductor device of FIG. 1, and FIG. 2B is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view illustrating a flow of a resin at the time of manufacturing the semiconductor device of FIG. 1;

FIG. 4 is a cross-sectional view showing a modification of the semiconductor device of the embodiment.

FIG. 5A is a plan view showing a schematic configuration of a conventional semiconductor device, and FIG. 5B is a sectional view taken along line BB of FIG.

6A is a plan view of a heat sink in the semiconductor device of FIG. 5, and FIG. 6B is a cross-sectional view taken along line CC of FIG.

FIG. 7 is a sectional view of a conventional semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Semiconductor chip, 3 ... Lead frame, 3a ... Island part, 3b ... Inner lead, 3c ...
Outer lead, 10: heat sink, 10a: heat transfer part, 10
b: thermal diffusion portion (outer edge), 10c: projecting portion.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 4M109 AA01 BA01 CA21 DB02 DB04 FA04 GA05 5F036 AA01 BB01 BE01 5F061 AA01 BA01 CA21 DD12 FA05 5F067 AA03 AB03 CA02 CA05

Claims (2)

[Claims] A lead frame (3) on which a semiconductor element (2) is mounted is disposed on one surface of a heat sink (10),
In the resin-encapsulated semiconductor device in which the heat radiating plate (10), the semiconductor element (2) and the lead frame (3) are sealed with a resin (5), the heat radiating plate (10) has an outer edge portion (10b). Are bent in a direction opposite to a side on which the lead frame (3) is arranged. 2. The radiating plate (10) has a protruding portion (10) protruding in a direction opposite to a side on which the lead frame (3) is disposed.
c), and the amount of bending of the outer edge portion (10b) is
2. The resin-encapsulated semiconductor device according to claim 1, wherein the protrusion amount is smaller than c).