JPS61168248A - Resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To increase the density of a wiring pattern of a printed board by forming leads of a semiconductor device molded with resin and having a heat sink fin and leads, and disposing the fin at the upper position. CONSTITUTION:A semiconductor element is mounted on a heat sink fin 23', wire-bonded to leads 22, and packaged in a resin molding layer 21. The leads 22 are formed to connect with a wiring copper foil pattern on a printed board 31. On the other hand, the fin 23' is not formed with the leads. Thus, the prescribed interval is provided between the fin 23' and the leads 22. Thus, since the fin 23' is separated an interval from the board 31, a wiring pattern 32' may be also provided on the printed board directly under the fin 23'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a resin-sealed semiconductor device using a thin package provided with radiation fins.

[Technical background of the invention]

Resin packages are widely used because they are cheaper than ceramic packages, especially as shown in Figure 2 (A>
Alternatively, the demand for packages having the shape shown in (B) has been increasing in recent years due to the demand for miniaturization of devices.

In the same figure (A>(B), 1 is an envelope made of a resin mold layer, 2... and 2'... are lead pins. In the case of FIG. 2(A), the resin envelope is The lead pins 2 extending from the side wall of 1 are bent to the bottom level of the envelope, and then their tips are folded back approximately parallel to the bottom of the envelope. The one in (B) extends from the side wall of the envelope 1 and is bent to the bottom level of the envelope, and the dobbin 2'... is terminated as it is.The only difference between the two is this point. , all other structures are the same.In either case, a semiconductor chip (not shown) is sealed in the interior 1.2 of the envelope 1, and lead pins 2
..., 2'... are bonded to internal terminals of this semiconductor chip.

In the resin-sealed semiconductor device shown in FIGS. 2(A) and (B) above,
The thickness of the resin envelope 1 is extremely thin compared to a normal DIP type package, and for this reason it is generally called a flannel package type, but there is no clear definition of the flannel package type. 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 pins and in which one lead is formed for flat mounting is referred to as a flat package.

Although the flat package described above 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. That is, a resin envelope originally has low heat dissipation properties, 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, the package will become very large and go against the demand for miniaturization, but it will still consume a certain amount of power (for example, It is possible to obtain a heat dissipation effect that can cover up to 100 bottles). However, in a thin envelope of a flat package, the absolute amount of heat dissipated by the resin mold layer is small, so there is a problem 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 increased functionality, and even devices that consume considerable power are required to be mounted in a flat package type. In order to meet this demand, the inventor first proposed a flat package provided with radiation fins as shown in FIGS. 3(A) and 3(B) (Japanese Patent Application No. 58-244557). 3(A) respectively correspond to FIG. 2(A>), in which 11 is an envelope made of a resin mold layer, 12... are lead pins, and 13 are heat radiation fins.

On the other hand, the resin-sealed semiconductor device shown in FIG. 3(C)
The structure differs from the structure shown in FIG. 2A in that the lead pins 22 and radiation fins 23 and 23 extend from the side wall of the resin mold layer 21 in only two directions. However, it is similar to the structure shown in FIG. 3A in that the envelope 21 is thin, and the dowels 22... and the radiation fins 2, 3, 23 are formed into a shape for flat mounting. This is also classified as a flat package type.

By providing heat dissipation fins as shown in Figure 3 (A) and (B) above, the heat dissipation performance of flat packages has been significantly improved, making it possible to expand the range of applications to devices with considerable power consumption. .

Incidentally, a heat dissipation fin can be similarly provided for a lead forming type flat package as shown in FIG. 2(B).

[Problems with background technology]

However, the above-mentioned conventional resin-sealed semiconductor device using a flat package provided with heat dissipation fins has a problem in that when it is mounted on a printed wiring board, it impedes improvement in the wiring density of the printed wiring board.

FIG. 4 is an explanatory diagram illustrating this problem using the resin-sealed semiconductor device of FIG. 3(B) as an example. In the figure, 31 is a substrate made of an insulating material such as glass epoxy;
A wiring pattern 32 made of copper foil is formed on one surface. In this case, the heat dissipation fin 23 is also connected to the lead pin 22.
Since the leads are formed in the same way as the wiring pattern 32..., if the wiring pattern 32... is formed in this area, the radiation fins 23 will come into contact with the wiring pattern and cause a short circuit. A wiring pattern cannot be formed in the radiation fin region. Therefore, the wiring pattern density of the printed circuit board is reduced by that amount, which is contrary to the demands for miniaturization and multifunctionality of devices.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and by providing a heat dissipation fin to a resin-sealed semiconductor device in a flat package, it is possible to expand the range of application thereof, and also to reduce the wiring pattern density of a printed wiring board structure. It is an object of the present invention to provide a resin-sealed semiconductor device that can avoid such problems.

[Summary of the invention]

A resin-sealed semiconductor device according to the present invention includes: a semiconductor chip mounted on a heat radiation fin via a solder layer; a lead pin connected to an internal terminal formed on the surface of the semiconductor chip via a bonding wire; a resin mold layer for sealing the semiconductor chip, the semiconductor chip mounting portion of the radiation fin, and the wire bonding portion of the lead, the thickness of the resin mold layer being 15 times or less the thickness of the lead pin, and In a resin-sealed semiconductor device configured to be flat-mounted,
Among the lead pins and radiation fins extending from the resin mold layer, only the lead pins are lead-formed so that they can be mounted on a flat surface, and the radiation fins are positioned above the lead pins by a predetermined distance. It is something.

According to the present invention, it can be applied to devices that consume a considerable amount of power due to the action of the radiation fins, and since the radiation fins are located a predetermined distance above the lead pins, the wiring pattern formed on the surface of the printed circuit board can be easily applied. No contact. Therefore, it becomes possible to form a wiring pattern also in the area from the print 1 to the substrate under the heat dissipation fins.

In addition, in the present invention, since the semiconductor chip is mounted through a solder layer with high thermal conductivity, the heat dissipation fins work extremely effectively, and it is possible to obtain even better heat dissipation characteristics than in the past.

[Embodiments of the invention]

FIG. 1(A) is a perspective view showing a resin-sealed semiconductor device according to an embodiment of the present invention applied to the flat package of FIG. 3(B), mounted on a printed wiring board. In this figure, the same parts as in FIG. 3(B) and FIG. 4 are given the same reference numbers.
is a resin mold layer, 22... are lead pins, and 31 is an insulating printed circuit board. The composition of these parts is the third
Since it is the same as explained in Figure (B) and Figure 4,
The explanation will be omitted. On the other hand, 23' is a heat radiation fin. The heat dissipation fins 23' are different from the conventional heat dissipation fins 23 in that the heat dissipation fins 23' extend straight and horizontally from the side wall of the resin mold layer 21 as shown.

Next, the internal structure and manufacturing method of the resin-sealed semiconductor device according to the above embodiment will be explained.
This is carried out using a lead frame 40 shown in Figure (B). The lead frame 40 is formed by punching a thin metal plate into a predetermined pattern such as the lead portions 22 . . . and the radiation fins 23'. Figure 1 (A)
When manufacturing a resin-sealed semiconductor device, first, the semiconductor chip 24 is die-bonded onto the bed section provided at the center of the heat dissipation fins 23', 23' via a solder layer, and then wires are bonded as shown in the figure. Perform bonding. Next, a resin mold layer 21 is formed using a transfer mold of epoxy resin or the like to seal the area indicated by the two-dot chain line in the figure, and then each pattern is separated from the outer frame 41 of the lead frame along the broken line in the figure. Furthermore, by bending and forming only the separated dobbin 22 into a predetermined shape, the shape shown in FIG. 1(A) is formed.
The shown flat-mount type resin-sealed semiconductor device is obtained.

In addition, among the through holes drilled in the radiation fin 23' in FIG. 1(B), the through hole 23'a near the resin sealing boundary
... is for strengthening the holding power of the fin by the resin mold layer. That is, since the resin mold layer is thin in the flat mounting type, it provides the strength required when bending the fin. In addition, the through hole 23'b provided near the bed portion prevents the flow of molten solder during die bonding of the semiconductor chip 24, so as not to interfere with wire bonding to the heat dissipation fin. Furthermore, a heat radiation fin 23'.

23' has sealed parts on both sides of the bed part,
The reason why the width is narrow is as follows. The first reason is to prevent heat from being transmitted 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 caused by bending and forming the fins from spreading to the inside of the resin mold layer, and to prevent the moisture resistance from decreasing due to the formation of gaps.

The effects of the resin-sealed semiconductor device according to the embodiment shown in FIG. 1 (A>(B)) will be explained as follows.

First, since the radiation fins 23' extend horizontally, the printed wiring board 31 is
In the case of planar mounting on top, a distance Md is maintained between the radiation fin 23' and the surface of the printed circuit board. Therefore, the wiring pattern 32' can be formed also in the substrate surface area under the radiation fin without causing short circuits, and it is possible to improve the wiring density and reduce the size of the device.

Secondly, since the semiconductor chip 24 is mounted on the mount 1 on the heat dissipation fin 23 via the solder layer as described above, an effective effect of the heat dissipation fin can be obtained. That is, since the silver/epoxy conductive adhesive used as the mounting agent for the semiconductor chip in the conventional flat package resin-sealed semiconductor device has low thermal conductivity,
There was a problem in that heat conduction from the semiconductor chip to the heat radiation fins was inhibited, and effective heat radiation was not performed. On the other hand,
In the above embodiment, since it is mounted with a solder layer having excellent thermal conductivity, the conventional inhibition of heat conduction is eliminated and a sufficient heat dissipation effect is achieved. As a result, the range of application of a resin-sealed semiconductor device with a thin flat-mounted envelope can be expanded to devices with medium output. Further, since the solder layer has a low electric resistance, it does not cause any problem even in a structure in which the potential of the substrate region is extracted from the back surface of the chip. Furthermore, since solder has a lower content of impurities such as halogen ions than conductive adhesives such as silver/epoxy resin, occurrence of defects such as corrosion can be reduced.

FIG. 5 is a perspective view showing another embodiment of the present invention. This embodiment differs from the embodiment shown in FIG. 1A in that the radiation fins 23'' extending horizontally from the side wall of the resin mold layer 21 are further bent upward; This is exactly the same as the embodiment shown in FIG. 1(A). In this embodiment as well, a sufficient distance is maintained between the heat dissipation fin 23'' and the surface of the printed wiring board 31, so that the board under the heat dissipation fin The wiring pattern 32' can also be formed in the surface region, and it is possible to improve the wiring density and downsize the device. It also reduces the contact resistance of semiconductor chips,
Similar effects, such as corrosion prevention, can be obtained by mounting with a solder layer.

Although the above embodiments are all examples in which the present invention is applied to the resin-sealed semiconductor device shown in FIG. 3(B), the present invention applies to the resin-sealed semiconductor device shown in FIG. 3(A). It is also possible to apply the same to

In this case, all of the radiation fins 13 provided in the four directions may have the same shape as the radiation fins in FIG. 1 (A) or FIG. may have the same shape as the radiation fins in FIG. 1(A) or FIG. 5.

〔Effect of the invention〕

As detailed above, according to the present invention, the effect of the heat dissipation fin provided in a flat packaged resin-sealed semiconductor device is enhanced, the range of application thereof is further expanded, and the wiring pattern density of a printed wiring board structure is reduced. It is possible to obtain remarkable effects, such as being able to avoid such problems.

[Brief explanation of the drawing]

FIG. 1(A) is a perspective view showing a state in which a resin-sealed semiconductor device according to an embodiment of the present invention is mounted on a printed wiring board, and FIG. 1(B) shows its manufacturing process and internal structure. 2(A) and 2(B) are perspective views showing a resin-sealed semiconductor device in a conventional flat package without heat dissipation fins, and FIG. 3(A)(B) is a plan view for explaining the
) is a perspective view showing the appearance of a resin-sealed semiconductor device in a conventional flat package with radiation fins;
The figure is an explanatory view showing the problem, and FIG. 5 is a perspective view showing a resin-sealed semiconductor device according to another embodiment of the present invention. 21... Resin mold layer, 22... Lead pin, 2
3.23'-=radiating fins, 23a, 23b. 23'a, 23'b...Through hole, 24...Semiconductor chip, 25...Honding wire, 31...
Printed wiring board, 32...Copper foil pattern for wiring, 40...Lead frame, 41...Lead frame outer frame Applicant's representative Patent attorney Takehiko Suzue-15= Castle 3 Castle

Claims (1)

[Claims] A semiconductor chip mounted on a heat dissipation fin via a solder layer, a lead pin connected to an internal terminal formed on the surface of the semiconductor chip via a bonding wire,
a resin mold layer for sealing the semiconductor chip, the semiconductor chip mounting portion of the radiation fin, and the wire bonding portion of the lead, and the thickness of the resin mold layer is 15 times or less than the thickness of the lead pin; In a resin-sealed semiconductor device configured to be flat-mounted, of the lead pins and radiation fins extending from the resin mold layer, only the lead pins are lead-formed so as to be flat-mounted, and the radiation fins are A resin-sealed semiconductor device characterized by being positioned above the lead pin by a predetermined distance.