JPH0320067B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a planar mounting form of a resin-sealed semiconductor device, and in particular, to a planar mounting form of a resin-sealed semiconductor device in a thin package. This relates to a planar mounting form.

[Technical background of the invention]

Resin packages are widely used because they are cheaper than ceramic packages, and in particular, the demand for packages with the shape shown in Figure 2 A or B has increased in recent years due to the demand for smaller equipment. is showing.

In the figures A and B, 1 is an envelope made of a resin mold layer, and 2... and 2'... are lead pins.
In the case of Fig. 2A, the lead pins 2 extending from the side wall of the resin envelope 1 are bent to the bottom level of the envelope, and then their tips are bent approximately parallel to the bottom of the envelope. In contrast, in the case shown in FIG. 1B, the lead pins 2' extend from the side wall of the envelope 1 and are bent to the bottom level of the envelope, and are terminated as they are. The two differ only in this point; all other structures are the same. In either case, a semiconductor chip (not shown) is sealed inside the envelope 1, and the lead pins 2..., 2'... are bonded to internal terminals of this semiconductor chip.

In the resin-sealed semiconductor devices shown in FIGS. 2A and 2B above, the thickness of the resin envelope 1 is extremely thin compared to a normal DIP package, and for this reason it is generally called a flat package type. , there is no clear definition of a flat package. Therefore, in this specification, a resin-sealed package in which the thickness of the resin envelope is 15 times or less than the thickness of the lead pin and which is lead-formed so as to be mounted on a flat surface will be referred to as a flat package.

[Problems with background technology]

Although the above-mentioned flat package has the advantage of being able to miniaturize the resin-sealed semiconductor device as described above, it has the following problem in terms of heat dissipation.

In other words, the resin envelope originally has low heat dissipation, and
The heat dissipation effect of a resin-sealed package basically depends on the size of the envelope. For this reason, if the package is relatively large, such as a DIP package,
Although the envelope becomes very large and goes against the demand for miniaturization, it is still possible to obtain a heat dissipation effect that can cover up to a certain amount of power consumption (for example, one with about 100 pins). However, since the absolute amount of heat dissipated by the resin mold layer in a flat package thin envelope is small, there is a problem in that the scope of application must be limited to those with low power consumption.

On the other hand, user needs for resin-sealed semiconductor devices include greater weight, smaller size, and multifunctionality, and even devices that consume a considerable amount of power are required to be mounted in a flat package type. In order to meet this demand, the inventor proposed a flat package provided with heat dissipation fins, but even in this case, the scope of application has not yet been expanded to the extent that the demand can be fully met. Problems remain, especially in the case of single-piece mounting.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and was made with the aim of expanding the scope of application of resin-sealed semiconductor devices using flat packages. This is intended to further improve the heat dissipation effect.

[Summary of the invention]

The present invention provides a method for mounting a resin-sealed semiconductor device on a printed wiring board using a flat package of a flat mounting type provided with heat dissipation fins. A heat dissipation pattern is provided, and when the resin-sealed semiconductor device is planarly mounted on a printed wiring board, heat dissipation purification is improved by bonding the heat dissipation fin to the heat dissipation pattern formed on the printed wiring board. It is something.

That is, the planar mounting form of the resin-sealed semiconductor device according to the present invention includes a semiconductor chip mounted on a heat dissipation fin via a solder layer, and an internal terminal formed on the surface of the semiconductor chip via a bonding wire. The resin mold layer includes a connected lead pin, a resin mold layer that seals the semiconductor chip, a semiconductor chip mounting portion of the heat dissipation fin, and a wire bonding portion of the lead, and the thickness of the resin mold layer is equal to the thickness of the lead pin. The resin-sealed semiconductor device is composed of a resin-sealed semiconductor device having a size of 15 times or less and configured to be flat-mounted, and a printed wiring board on which a wiring pattern and a heat dissipation pattern are formed. Each of the lead pins is bonded to the wiring pattern, and the heat dissipation fin is bonded to the heat dissipation pattern for planar mounting.

According to the present invention, in addition to the heat dissipation effect of the heat dissipation fins, the heat dissipation effect of the heat dissipation pattern on the printed wiring board can be obtained, and as a result, it can be applied even to devices with a considerable amount of power consumption, and can be applied to flat packages. This makes it possible to meet demands for expanded range.

[Embodiments of the invention]

First, a flat package resin-sealed semiconductor device to which the mounting form of the present invention is applied will be explained. FIGS. 3A to 3C are perspective views showing an example thereof. 2A and B, in which 11 is an envelope made of a resin mold layer, 12, 12'... are lead pins,
13 and 13' are heat radiation fins. These resin-sealed semiconductor devices shown in FIGS. 3A and 3B have exactly the same structure except that the forming shapes of the lead pins and heat dissipation fins are different.

On the other hand, the resin-sealed semiconductor device shown in FIG.
This structure differs from the structures shown in FIGS. A and B in that the structure extends from the side wall of the resin mold layer 21 in only two directions. However, the case A in FIG.
This is also classified as a flat package type.

Next, the internal structure and manufacturing method of a resin-sealed semiconductor device using a flat package with heat dissipation fins will be explained using the device shown in FIG. 3C as an example. This is done using The lead frame 30
A predetermined pattern of lead portions 22, heat dissipation fins 23, etc. is formed by punching a thin metal plate. When manufacturing the resin-sealed semiconductor device shown in FIG.
After the semiconductor chip 24 is die-bonded onto the bed portion provided at the center of the semiconductor chips 3 and 23 using a mounting agent such as a silver/epoxy adhesive, wire bonding is performed as shown in the figure. Next, a resin mold layer 21 is formed to seal the area indicated by the dashed line in the figure with a transfer mold of epoxy resin or the like.
After forming, each pattern is separated from the outer frame of the lead frame along the broken line in the figure. Further, by bending and forming the separated leads 22 and the heat dissipating fins 23, 23 into a predetermined shape, a flat mount type resin-sealed semiconductor device shown in FIG. 3C is obtained.

In addition, among the through holes drilled in the heat dissipation fin 23 in FIG. 4, the through hole 2 near the resin sealing boundary
3a... is for strengthening the holding power of the fins by the resin mold layer. On the other hand, since the resin mold layer of the flat mount type is thin, it provides the strength required when bending the fins. In addition, a through hole 23b provided near the bed portion
This prevents the flow of the mounting agent during die bonding of the semiconductor chip 24, so as not to interfere with wire bonding to the heat dissipation fin. Furthermore, the sealing portions of the heat dissipating fins 23, 23 on both sides of the bed portion are constricted and the width thereof is narrow for the following reason. The first reason is
This is to control the transmission of heat to the semiconductor chip 14 when the fins are soldered to the heat sink portion of the printed wiring board. The second reason is to avoid the mechanical stress that occurs when bending and forming the fins from spreading to the inside of the resin mold layer.
This is to prevent a decrease in moisture resistance due to the formation of gaps.

Note that the structure shown in FIG. 3A or B in which heat dissipation fins and lead pins are provided in four directions can also be manufactured in the same manner as described above by using a lead frame formed in such a pattern.

Next, the mounting mode according to the present invention is applied to the resin-sealed semiconductor device of FIG. 3A having the above structure,
An embodiment in which the heat dissipation effect of the heat dissipation fins 13 is improved will be described.

FIG. 1 is a perspective view showing this embodiment, in which the resin-sealed semiconductor device in the form of a flat package shown in FIG. 3A is mounted on a printed wiring board 40. The printed wiring board 40 consists of a part 41 for planar mounting of a resin-sealed semiconductor device, and a plug part 42 for incorporating this into another circuit board, and a copper foil pattern 43 for wiring on the surface of the mounting part... In addition, copper foil patterns 44 for heat radiation are formed. Further, this printed wiring board 40 has a laminated structure using glass epoxy boards, and the copper foil pattern 43 for wiring formed on the mounting part is formed on the surface of the plug part 42 via an internal wiring layer. It is connected to the copper foil patterns 45... In the resin-sealed semiconductor device of FIG. 3A, the lead pins 12 are soldered onto the terminals of the wiring pattern 34 formed on the surface of the printed circuit board mounting portion 41, and the heat dissipation fins 13 are mounted on the board. Heat dissipation pattern 44 formed on the surface of part 41
It is mounted on a flat surface by soldering on top.

In the mounting form of the above embodiment, the heat dissipation fins 23 of the flat-mounted resin-sealed semiconductor device are attached to the copper foil patterns 44 for heat dissipation, which do not have a wiring function, and are formed on the surface of the mounting part of the printed wiring board. By soldering, the substantial heat radiation area of the heat radiation fin is increased. As a result, compared to the case where only the heat dissipation fins 13 are used, the heat dissipation copper foil pattern 44
A large heat dissipation effect is reliably obtained by the amount of heat dissipated by..., and the flat package can be applied to semiconductor chips with high power consumption, which was previously impossible. In fact, when we changed the width of the heat dissipating copper foil patterns 44 in the mounting form of the above embodiment and examined the possible power consumption within the semiconductor chip in the same package, we found that there was a clear dependency between the two. The effectiveness of the heat dissipation copper foil pattern 44 was confirmed.

FIG. 5 is a perspective view showing another embodiment in which the mounting form according to the present invention is applied to the resin-sealed semiconductor device of FIG. 3A. In this embodiment, the entire back surface of the printed wiring board mounting section 41 is covered with a copper foil 46, and the heat dissipation copper foil pattern 43 formed on the surface...
extends along the side wall of the mounting section 41 and is connected to the copper foil 46 on the back surface. The rest of the structure is exactly the same as the embodiment shown in FIG. In this embodiment, in addition to the heat dissipating copper foil patterns 43 formed on the surface of the printed circuit board mounting section 41, the heat dissipation effect is added by the large-area copper foil 46 formed on the entire back surface of the printed circuit board mounting section. Even when compared with the embodiment shown in the figure, it is possible to obtain several times more heat dissipation, making it possible to apply the flat package to a semiconductor chip that consumes a large amount of power.

By the way, it is also possible to selectively expose the iron plate used as a core material in the inner layer of the wiring board 40 and to increase the effect of the heat dissipation fins by soldering the heat dissipation fins 23 to the exposed portions. However, in this case, since the exposed area of the iron plate is extremely small, the effect is inevitably inferior to that of the above embodiment.

The above embodiments are all applied to the mounting of the resin-sealed semiconductor device shown in FIG. 3A, but the present invention is applicable to the resin-sealed semiconductor device shown in FIGS. 3B and 3C. It can be applied in the same way.

Furthermore, although the lead pins are provided in four directions as in FIG. 3A, the heat dissipation fins can be similarly applied to resin-sealed semiconductor devices in which the heat dissipation fins are provided in three directions, two directions, or only one direction. can.

Furthermore, the same foil patterns 43 for heat radiation may be formed into any planar pattern shape.

〔Effect of the invention〕

As detailed above, according to the present invention, the heat dissipation effect of the heat dissipation fins is increased without significantly changing the specifications of the printed wiring board used for mounting the flat package from the conventional one, and the heat dissipation effect of the heat dissipation fins is increased. Remarkable effects such as the ability to significantly expand the range of application of thin resin-sealed semiconductor devices can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a mounting form of a resin-sealed semiconductor device according to an embodiment of the present invention, and FIGS. 2A and B
3 is a perspective view showing a conventional resin-sealed semiconductor device in a flat package, and FIGS. 3A to 3C show external appearances of a resin-sealed semiconductor device in a flat package with heat dissipation fins to which the mounting form of the present invention is applied. FIG. 4 is a plan view for explaining the manufacturing process and internal structure of the resin-sealed semiconductor device shown in FIG. 3C, and FIG. FIG. 11, 21...resin mold layer, 12, 12',
22... Lead pin, 13, 13', 23... Heat radiation fin, 23a, 23b... Through hole, 24... Semiconductor chip, 25... Bonding wire, 30
... Lead frame, 40 ... Printed wiring board, 41 ... Mounting section, 42 ... Plug section, 43,
45... Copper foil pattern for wiring, 44... Copper foil pattern for heat radiation, 46... Copper foil.

Claims (1)

[Claims] 1. A semiconductor chip mounted on a heat dissipation fin via a solder layer, lead pins connected via bonding wires to internal terminals formed on the surface of the semiconductor chip, the semiconductor chip, and the semiconductor chip of the heat dissipation fin. The device is provided with a resin mold layer that seals a mount portion and a wire bonding portion of the lead, and the resin mold layer has a thickness of 15 times or less than the thickness of the lead pin, and is configured to be flat-mounted. It is composed of a resin-sealed semiconductor device and a printed wiring board on which a wiring pattern and a heat dissipation pattern are formed, each lead pin of the resin-sealed semiconductor device being joined to the wiring pattern, and the heat dissipation fin A flat-mounted form of a resin-sealed semiconductor device, characterized in that the resin-sealed semiconductor device is flat-mounted by being bonded to the heat dissipation pattern.