JP2005050950A - Hollow package and semiconductor device - Google Patents

Abstract

A hollow package and a semiconductor device are provided which can improve heat dissipation and can be thinned.
A heat dissipation plate 3 having a resin film 2 and a lead frame 4 are provided, and the heat dissipation plate and the lead frame are sealed with resin so that the entire surface except the surface on which the resin film is formed is exposed. The hollow package 1, the semiconductor chip 7 bonded to the surface on which the resin film of the heat sink is formed by the adhesive 6 and connected by the lead frame and the Au thin wire 8, and disposed above the semiconductor chip, the hollow A semiconductor device comprising a lid 9 for closing an opening of a package.
[Selection] Figure 2

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow package and a semiconductor device. Specifically, the present invention relates to a hollow package and a semiconductor device excellent in heat dissipation.
[0002]
[Prior art]
Conventionally, a sardip package in which a lead frame is sandwiched between a window frame made of ceramic and a base frame via a low-melting glass has been widely used as a package for a semiconductor device, particularly a solid-state imaging device.
However, in recent years, hollow plastic packages have come to be used due to demands for cost reduction, high accuracy, and light weight of the package.
[0003]
Here, as shown in FIG. 3, in the hollow plastic package, a predetermined pattern is etched or pressed in advance between mold dies processed so as to secure a hollow portion 101 for mounting a semiconductor element after molding. Is formed by injecting a mold resin 103 made of a thermosetting epoxy resin or the like into a mold, and sandwiching the lead frame 102 made of a metal such as 42 alloy formed by a technique such as Plating or the like is performed, and the outer lead 105 is further bent into a predetermined shape.
[0004]
Thereafter, the semiconductor element 106 is die-bonded directly to the mold resin at the bottom of the hollow portion of the hollow plastic package with silver paste or the like, and a gold wire 108 is wire-bonded between the aluminum electrode 107 on the semiconductor element and the inner lead, thereby mutual bonding. After securing the electrical continuity, a lid 109 made of a flat light-transmitting material such as glass is attached via an adhesive made of a thermosetting epoxy resin so as to close the opening of the hollow plastic package. Thus, a solid-state imaging device can be obtained.
[0005]
By the way, in the case of a sardip package that has been widely used in the past, the thermal conductivity of the ceramic, which is the material of the package, is as high as about 16 W / (m · K), and most of the heat generated during operation of the semiconductor element is on the back side of the package. Since heat can be radiated into the atmosphere through the base frame, for example, when a solid-state image sensor is mounted as a semiconductor element, the level of white defects (hereinafter referred to as dark white points) that appear in dark imaging is not a problem. It was.
[0006]
However, instead of the sardip package, a hollow plastic package has been used as a package for a solid-state imaging device, and the white point level in the dark cannot be ignored. That is, in the case of a hollow plastic package, the thermal conductivity of the mold resin that is the material of the package is about 0.8 W / (m · K), which is about 1/20 that of ceramics. The generated heat could not be sufficiently dissipated into the atmosphere, and as a result, the temperature of the solid-state imaging device itself rose, and the white point level in the dark became worse.
[0007]
In order to solve the problems as described above, as a semiconductor device having an effect of radiating heat generated during operation of the semiconductor element, a moisture-resistant plate having a heat radiation effect is embedded in the resin at the bottom of the semiconductor element mounting surface of the hollow plastic package. A semiconductor device (for example, refer to Patent Document 1), a semiconductor device (for example, refer to Patent Document 2) in which an island part which is a part of a lead frame is formed of a metal plate having a heat dissipation effect, and a heat dissipation mechanism component on the island. There has been proposed a semiconductor device having a structure in which a semiconductor element is die-bonded with silver paste or the like on a heat dissipation mechanism component (see, for example, Patent Document 3).
[0008]
[Patent Document 1]
Japanese Patent No. 3080236 (page 1-3, Fig. 1)
[0009]
[Patent Document 2]
Japanese Patent No. 2539111 (page 1-4, FIG. 2)
[0010]
[Patent Document 3]
Japanese Patent No. 3054576 (page 1-4, FIG. 1)
[0011]
[Problems to be solved by the invention]
However, in the structure in which the moisture-resistant plate having a heat dissipation effect as described above is completely embedded in the resin, heat generated during operation of the semiconductor element is released from the moisture-resistant plate to the outside through the resin. , Sufficient heat dissipation cannot be obtained.
[0012]
In addition, in the lead frame having an island part as described above, the plate thickness of the island part itself is thinner than the package thickness, and instead the resin having low thermal conductivity is thickened. Cannot be obtained. Furthermore, in the structure in which the metal surface of the island portion that is electrically connected to the lead frame is exposed to the outside, there is a problem in that plating is performed up to a surface that does not require plating, which increases the plating cost.
[0013]
Further, in the method for securing the heat transfer path by directly connecting the semiconductor element and the heat dissipation mechanism parts as described above, the island portion exposed on the back surface of the semiconductor element and the lead frame or the back surface of the package after the assembly of the semiconductor device. Are electrically connected, and there is a concern that the operation of the semiconductor element may be adversely affected.
[0014]
In recent years, the demand for miniaturization of AV equipment has been increasing year by year, and the semiconductor devices mounted on the AV equipment are demanding light, thin and small semiconductor devices from the viewpoint of high-density mounting and light weight.
[0015]
The present invention has been made in view of the above points, and an object of the present invention is to provide a hollow package and a semiconductor device that can improve heat dissipation and can be thinned.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a hollow package according to the present invention includes a heat sink having an insulating layer formed on a surface on which a semiconductor chip is mounted, and a lead frame connected to the semiconductor chip by a bonding wire, The heat radiating plate and the lead frame were sealed with resin so that the entire surface of the heat radiating plate except the surface on which the semiconductor chip was mounted was exposed.
[0017]
In order to achieve the above object, a semiconductor device according to the present invention includes a heat sink having an insulating layer and a lead frame, and the entire surface of the heat sink excluding the surface on which the insulating layer is formed. A hollow package in which the heat sink and the lead frame are resin-sealed so as to be exposed, a semiconductor chip mounted on the surface on which the insulating layer is formed, and connected to the lead frame by a bonding wire, A lid is provided above the semiconductor chip and closes the opening of the hollow package.
[0018]
Here, the heat sink formed on the surface on which the insulating chip is mounted on the semiconductor chip eliminates the need to secure the insulating property between the heat sink and the semiconductor chip by the mold resin, and the semiconductor device can be thinned.
That is, when there is no insulating layer on the surface on which the semiconductor chip is mounted, as shown in FIG. 4, a mold resin is placed between the heat sink and the semiconductor chip to ensure the insulation between the heat sink 110 and the semiconductor chip. In the case where an insulating layer is provided on the surface on which the semiconductor chip is mounted, it is not necessary to secure the insulation between the heat sink and the semiconductor chip by the mold resin, thereby reducing the thickness of the semiconductor device. be able to. In consideration of molding the hollow package by the transfer molding method, a width of about 0.3 mm is necessary for the mold resin to flow, and the gap between the heat sink and the semiconductor chip indicated by symbol A in FIG. The thickness of the mold resin to be interposed also needs to be about 0.3 mm.
[0019]
In addition, the heat sink and the lead frame are sealed with resin so that the entire surface excluding the surface on which the semiconductor chip is mounted is exposed, so that heat generated during operation of the semiconductor chip is passed through the heat sink exposed from the hollow package. Can be released to the outside.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings to provide an understanding of the present invention.
FIG. 1 is a schematic sectional view for explaining an example of a hollow package to which the present invention is applied. The hollow package 1 shown here has a resistance value of 10 ¹⁰ Ω on its surface and a film thickness of about 2 μm. A heat dissipation plate 3 having a thermal conductivity of 1 W / (m · K) or more on which the resin film 2 is formed, and a lead frame 4 electrically connected by a bonding wire to a semiconductor chip mounted on a hollow package are radiated heat. Sealing is performed by the mold resin 5 so that the surface of the plate on which the resin film is formed, that is, the entire surface excluding the surface on which the semiconductor chip is mounted is exposed. The lead frame is arranged so that the surface on which the resin film is formed and the inner lead portion are in contact.
[0021]
Here, the insulating layer formed on the heat radiating plate is sufficient if the signal leakage current value can be suppressed to a certain level or less, and does not necessarily need to be a resin film, and may be oxide, sulfide, nitride, or the like. It doesn't matter.
Of course, when the heat sink is formed of an insulating material, it is not necessary to form an insulating layer on the heat sink.
[0022]
The heat sink is made of a material having a thermal conductivity of 1 W / (m · K) or more made of a metal, an inorganic compound, an oxide, a resin, or a composite thereof. As a material for the heat sink, for example, Cu, Al, Fe, WC, AlN, Al ₂ O _{3 and the} like can be selected and used. In order to obtain sufficient heat dissipation, the thermal conductivity is 1 W / ( m · K) or more is required, and preferably 10 W / (m · K) or more. Here, when the thermal conductivity is less than 1 W / (m · K), the white point in the dark may be a problem.
Although the shape of the heat sink is desirably about the same as or larger than the size of the semiconductor chip, it is considered that heat dissipation can be ensured if the heat sink has an area about half that of the semiconductor chip.
[0023]
The sealing resin for molding the hollow package is preferably molded from a thermosetting resin such as an epoxy resin, a polyimide resin, a phenol resin, or an unsaturated polyester resin, or a heat-resistant plastic positive resin such as a polysulfone resin.
[0024]
Furthermore, the lead frame is desirably formed of 42 alloy, copper alloy, or the like, and the lead frame can be subjected to Ni plating, Ag plating, Au plating, solder plating, or the like as required.
[0025]
Here, it is sufficient that the lead frame can electrically connect the semiconductor chip and the external substrate, and it is not always necessary that the heat dissipation plate on which the resin film is formed and the inner lead portion are in contact with each other. The lead frame can be expected to improve the wire bonding accuracy between the semiconductor chip mounted on the heat sink and the inner lead by supporting the inner lead with the heat sink. It is preferable that they are arranged so that the portions are in contact with each other.
[0026]
In the above-described hollow package to which the present invention is applied, since the resin film is formed on the surface of the heat radiating plate on which the semiconductor chip is mounted, there is no need to ensure the insulation between the semiconductor chip and the heat radiating plate. Therefore, it is not necessary to interpose a mold resin between the heat sink and the semiconductor device.
Further, the entire surface excluding the surface on which the semiconductor chip is mounted is exposed, and high heat dissipation can be realized.
[0027]
In addition, since the lead frame is disposed so that the surface on which the resin film is formed and the inner lead portion are in contact with each other, the semiconductor device can be made thinner without any molding resin interposed between the inner lead portion and the heat sink. It becomes possible.
Furthermore, since the inner lead portion is supported by the heat sink, it is expected that the wire bonding accuracy between the semiconductor chip mounted on the heat sink and the inner lead portion will be improved.
[0028]
The semiconductor chip 7 is bonded to the surface of the hollow package to which the present invention is applied with the resin film of the heat radiating plate with an adhesive 6 made of a heat conductive material, and the semiconductor chip and the inner lead portion are connected to the Au thin wire 8. After wire bonding is performed, the opening of the hollow package is closed with a lid 9 made of a flat light-transmitting material such as glass, whereby a semiconductor device to which the present invention is applied as shown in FIG. 2 can be obtained. .
[0029]
【The invention's effect】
As described above, the hollow package and the semiconductor device of the present invention can improve heat dissipation and can be thinned.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining an example of a hollow package to which the present invention is applied.
FIG. 2 is a schematic cross-sectional view for explaining an example of a semiconductor device to which the present invention is applied.
FIG. 3 is a schematic perspective view for explaining a conventional hollow plastic package.
FIG. 4 is a schematic cross-sectional view for explaining a conventional semiconductor device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hollow package 2 Resin film 3 Heat sink 4 Lead frame 5 Mold resin 6 Adhesive 7 Semiconductor chip 8 Au fine wire 9 Lid

Claims (6)

A heat sink having an insulating layer formed on the surface on which the semiconductor chip is mounted;
A semiconductor chip and a lead frame connected by bonding wires;
A hollow package, wherein the heat radiating plate and the lead frame are resin-sealed so that the entire surface excluding the surface on which the semiconductor chip is mounted is exposed. The hollow package according to claim 1, wherein an inner lead portion of the lead frame is in contact with a surface on which the semiconductor chip is mounted. The hollow package according to claim 1, wherein the heat radiating plate has a thermal conductivity of 1 W / (m · K) or more. A hollow package comprising a heat sink having an insulating layer formed thereon and a lead frame, wherein the heat sink and the lead frame are resin-sealed so that the entire surface excluding the surface on which the insulating layer is formed is exposed. When,
A semiconductor chip mounted on the surface on which the insulating layer is formed, and connected to the lead frame by a bonding wire;
A semiconductor device comprising a lid disposed above the semiconductor chip and closing an opening of the hollow package. The semiconductor device according to claim 4, wherein an inner lead portion of the lead frame is in contact with a surface on which the insulating layer is formed. The semiconductor device according to claim 4, wherein the heat dissipation plate has a thermal conductivity of 1 W / (m · K) or more.

Images