JPH04364771A - Semiconductor device and lead frame used therefor - Google Patents

Abstract

PURPOSE:To reduce in size a package using a multilayer lead frame and to improve heat dissipation of the package. CONSTITUTION:At least one plate 12, 14 formed separately from a lead frame 10, is connected to the frame through an electrically insulating layer 16. A semiconductor chip 20 is placed on the plate, and the chip is electrically connected to the plate and the frame. The frame is held at the intermediate, a cap 22 is sealed oppositely to the plate, and connected to the frame thereby to seal the chip therein.

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 lead frame used therein.

0002

[Prior Art] Resin-sealed lead frames on which semiconductor chips are mounted include those equipped with a large stage separate from the frame body for bonding the semiconductor chip to improve heat dissipation; There is a multilayer lead frame that is provided by laminating a plurality of planes formed on the body. By using multiple layers of planes as power planes, ground planes, etc., multilayer lead frames can make electrical connections with semiconductor chips at arbitrary positions, and also reduce the number of power leads and ground leads allocated to the lead frame. There is an advantage that the number of effective pins of the lead frame can be increased by reducing the number of pins.

0003

[Problem to be Solved by the Invention] By the way, in the multilayer lead frame as described above, after mounting a semiconductor chip, all the planes installed in the multilayer are sealed in resin to produce a product, so the package is inevitably As it becomes thicker, the package has to become larger. There is also the problem that resin sealing reduces the heat dissipation of the package. Therefore, the present invention has been made to solve the above problems, and its purpose is to make use of the characteristics of the conventional multilayer lead frame, reduce the size of the package, and improve heat dissipation. The present invention aims to provide an excellent semiconductor device and a lead frame used therefor.

[0004] In order to achieve the above object, the present invention has the following configuration. That is, for a semiconductor device, at least one plane formed separately from a lead frame is bonded to the lead frame via an electrically insulating layer, a semiconductor chip is mounted on the plane, and the semiconductor chip and the plane are bonded together. and a lead frame, the semiconductor chip is sealed inside by sandwiching the lead frame in between, sealing a cap facing the plane, and bonding to the lead frame. . Further, a sealing frame for sealing the cap is bonded onto the lead frame. Further, in order to expand the internal space in which the semiconductor chip is mounted, a cap having a hat-like raised central portion is bonded to the lead frame. Further, the cap is characterized in that a protrusion with good thermal conductivity that comes into contact with the semiconductor chip is provided on the inner surface of the cap. Also,
Regarding the lead frame, at least one plane formed separately from the frame body is joined to the frame body via an electrically insulating layer, the frame body is sandwiched in between, and a cap is placed at a position facing the plane. It is characterized by the installation of a sealing frame for joining.

[0005]

[Operation] A semiconductor chip is housed in an interior whose upper and lower surfaces are sealed by a plane and a cap. The plane and cap are configured as casing members of the package, making it possible to miniaturize the package using a lead frame with multilayer planes, and by exposing the plane and cap to the outside, a package with excellent heat dissipation can be obtained. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of a semiconductor device according to the present invention. In the figure, 10 is a lead frame, and 12 and 14 are a power plane and a ground plane. The power plane 12 is a metal plate formed into a frame shape, and the ground plane 14 is made of a single metal plate. Electrical insulation is provided between the power plane 12 and the ground plane 14 and between the power plane 12 and the lead frame 10. In the embodiment, a power plane 12 and a ground plane 1 are connected with an electrically insulating layer 16 such as polyimide interposed therebetween.
4, the power supply plane 12, and the lead frame 10 are integrally joined. Lead frame 10 and power plane 1
2 and the ground plane 14 are made by connecting pieces 12 on the outer edges of the power plane 12 and the ground plane 14.
a, 14a are provided, and these connection pieces 12a, 14a are welded to the power line and ground line of the lead frame 10.

In FIG. 1, reference numeral 18 denotes a sealing frame that is grounded above the power plane 12 with the lead frame 10 in between. This sealing frame 18 is used to seal the semiconductor chip 20 by bonding the cap after mounting the semiconductor chip 20 thereon. In the embodiment, the seal frame 18 was bonded using a double-sided adhesive, but the method of bonding the seal frame 18 is not particularly limited, and may be bonded using an adhesive having electrical insulation properties. The ground plane 14 is connected to the semiconductor chip 2
After the semiconductor chip 20 is bonded, the semiconductor chip 20 is connected to the lead frame 10, the power plane 12, and the ground plane 14. The sealing frame 18 is provided to leave a certain distance above the semiconductor chip 20 for cap-sealing the semiconductor chip 20 and the power supply plane 18.
It is necessary to set this by taking into account the thickness of etc. Of course, the thickness of the electrically insulating layer provided between the seal frame 18 and the lead frame 10 may be adjusted.

FIG. 2 shows a sectional view of a lead frame in which the power plane 12, the ground plane 14, and the seal frame 18 described above are joined to the lead frame 10. As shown in the figure, a housing recess for mounting a semiconductor chip is formed in the center of the lead frame. A semiconductor chip is mounted on this lead frame, and in the embodiment, the semiconductor chip 20 is connected to the lead frame 10, the power plane 12, and the ground plane 14 by wire bonding, and the cap 22 is bonded to the sealing frame 18 to form a semiconductor device. get. FIG. 3 shows a perspective view of the semiconductor device thus obtained. In this semiconductor device, the upper and lower surfaces of the package are sealed by a cap 22 and a ground plane 14. The side surface of the package is sealed by bonding the cap 22, seal frame 18, lead frame 10, etc. with an adhesive. Sufficient sealing performance can be obtained between each member such as the lead frame 10 and the power supply plane 12 by sealing with an adhesive.

In order to improve the heat dissipation of the semiconductor chip 20, as shown in FIG. You can. This protrusion 24 is in contact with the upper surface of the semiconductor chip 20 to conduct heat generated by the semiconductor chip 20 to the cap 22, thereby improving the heat dissipation properties of the semiconductor chip 20.

In the semiconductor device of the above embodiment, as shown in FIG. 3, the cap 22 and the ground plane 14 are used as a casing part constituting a package, and the semiconductor chip is sealed within the package without resin molding. This allows the entire package to be made thin. Further, in this package, since the cap 22 and the ground plane 14 are exposed to the outside, heat is well dissipated from the cap 22 and the ground plane 14, and a semiconductor device with excellent heat dissipation properties can be provided. .

In the semiconductor device of the above embodiment, the cap 22
A lead frame in which a seal frame 18 was joined to a lead frame 10 was used to join the lead frame 10, but as shown in FIG.
By joining the lead frame to the seal frame 18
The cap can be sealed without using. By using the cap 26 of this embodiment, it is possible to secure a certain amount of space above the semiconductor chip 20, so that the semiconductor chip 20 and the lead frame 1 can be connected to each other by wire bonding.
It can also be easily connected to the inner lead of 0.

In the above embodiment, an example of a multilayer lead frame having a power plane 12 and a ground plane 14 was shown, but the multilayer lead frame is not limited to this embodiment. In other words, the present invention can be applied to a device having only a power plane, only a ground plane, or a device having other planes in addition to these planes. Note that at least one plane is required to be bonded to the lead frame in order to mount the semiconductor chip 20 thereon. Further, in the above example, the semiconductor chip and the plane are connected by wire bonding, but a connection method other than wire bonding, such as a connection method using TAB tape, can also be used.

Note that in the case of the semiconductor device using the multilayer lead frame of the above embodiment, since power planes, ground planes, etc. are laminated with an electrical insulating layer interposed between them, the signal line of the lead frame 10 is It has a microstrip line structure, and has the advantage that characteristic impedance matching can be achieved by appropriately setting the thickness of the electrical insulating layer, and the propagation characteristics of high-speed signals can be improved. The present invention has been variously explained above with reference to preferred embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in many ways without departing from the spirit of the invention. do not have.

[0014]

[Effects of the Invention] According to the semiconductor device and the lead frame used therein according to the present invention, as described above, it is possible to miniaturize the package of a semiconductor device having a multilayer plane, and the plane is not exposed to the outside. This can improve the heat dissipation of the package. In addition, it is possible to obtain a package with excellent electrical characteristics by taking advantage of the features of the multilayer lead frame.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a semiconductor device.

FIG. 2 is a sectional view showing an example of a lead frame.

FIG. 3 is a perspective view of an embodiment of a semiconductor device.

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

[Explanation of symbols]

10 Lead frame 12 Power plane 14 Ground plane 12a, 14a connection piece 16 Electrical insulation layer 18 Seal frame 20 Semiconductor chip 22, 26 Cap 24 Protrusion

Claims (5)

[Claims] 1. At least one plane formed separately from a lead frame is bonded to the lead frame via an electrically insulating layer, a semiconductor chip is mounted on the plane, and the semiconductor chip, the plane, and the leads are bonded to each other through an electrically insulating layer. A semiconductor device characterized in that a semiconductor chip is sealed inside by electrically connecting a frame, sandwiching the lead frame in between, sealing a cap facing the plane, and bonding to the lead frame. . 2. The semiconductor device according to claim 1, further comprising a sealing frame for sealing the cap bonded to the lead frame. 3. The semiconductor device according to claim 1, further comprising a cap having a hat-like raised central portion joined to the lead frame in order to enlarge the internal space in which the semiconductor chip is mounted. 4. The semiconductor device according to claim 1, wherein a protrusion having good thermal conductivity that contacts the semiconductor chip is provided on the inner surface of the cap. 5. At least one plane formed separately from the frame body is joined to the frame body via an electrically insulating layer, the frame body is sandwiched in between, and a cap is provided at a position facing the plane. A lead frame characterized by having a seal frame installed for joining.