JPH1167948A - Semiconductor package and package tray - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface-mounting type semiconductor package having a structure, wherein the mechanical strength and durability of outer lead terminals from a semiconductor device and the thermal characteristics of the package can be enhanced. SOLUTION: A plurality of projection parts 2 are adhered to the bottom of a semiconductor package 1 mounted on a mounting board 7. The height of these projection parts 2 is the same as that of a standoff 3, and the projection parts 2 come into contact with the surface of the board 7 along with outer leads 6 on the same surface of the board 7. By supporting a package 1 with the outer leads 6 and the projection parts 2, a load which is applied from the surface of the package 1, can be dispersedly supported by the outer leads 6 and the projection parts 2. Thereby, the mechanical strength and durability of outer lead terminals from a semiconductor device are improved and moreover, the thermal characteristics of the package 1 can be also modified by an increase in the surface area of the package.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package structure of a surface mount type semiconductor device (LSI) and a package tray for transporting the same, and more particularly, to the mechanical strength and durability of outer lead terminals from the LSI, and to the like. The present invention relates to a surface-mount type semiconductor package structure capable of improving the thermal characteristics of a package.

[0002]

2. Description of the Related Art FIG. 4 is a side view showing the structure of a recent surface-mount type semiconductor integrated circuit package 1, which is mounted on a mounting board 7 while maintaining a height called a standoff 3. FIG. This is maintained by bending the outer leads 4, but the package 1 is supported by the bending of the outer leads 4.

The purpose of the stand-off 3 is that, when a semiconductor integrated circuit or the like is surface-mounted on a board by soldering or the like and then washed, a space is left on the bottom surface of the semiconductor integrated circuit so that the cleaning agent passes through the space and causes dust or the like. Has the role of flowing. Furthermore, it is provided so that if an air flow is created during actual use, heat is also effectively removed.

[0004] In recent years, the number of LSI terminals has become very large in semiconductor integrated circuits due to an increase in chip size and functions. Surface mount plastic type QF
In P (PQFP), those with more than 340 pins are available. Therefore, the pitch of the external terminal leads is 0.5
from 0.4 mm to 0.4 mm. Furthermore, plastic-type packages are relatively inexpensive and can be used in all kinds of devices, but the disadvantages of plastic packages are their low heat radiation ability.

Therefore, in recent years, copper (C
Most have shifted to lead frames (L / F) having the composition u). Therefore, it is very easy to bend from the viewpoint of the pin strength, and is more easily bent at the time of assembling and delivering a product, at the time of mounting by a user, and after mounting.

There is also a movement to actively use the upper surface of the package after surface mounting, and the burden on the outer leads tends to increase. One of them is a structure in which a heat sink is further attached to the upper surface to release generated heat, a structure in which a soft cooling material called an ice cap is covered, and a structure in which a forced fan is attached.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-130273, there is a method for preventing bending of the outer lead portion by using a bumper portion. The feature of this conventional example is that the corner bumper covers the bending of the lead during assembly, transportation and mounting, preventing the bending etc. beforehand, and the strength and durability of the outer lead after mounting.・ It does not mention bending.

As described above, the mechanical load applied to the surface-mount type semiconductor integrated circuit is expected to increase in the future, but at present, no effective proposal has been made.

[0009]

Conventionally, a semiconductor package has a space called a stand-off of about 1 mm between itself and a substrate.
There is a disadvantage that the pin is necessarily bent.

The progress of semiconductors in recent years has been remarkable, and some products have exceeded several million transistors. For this reason, as one of techniques for suppressing heat generation or releasing heat, a configuration in which a structure such as a heat sink is attached to the upper surface of a package is implemented. Therefore, a large load from the top of the product is applied even after mounting.

In order to support the load and maintain the stand-off, conventionally, only the outer lead supports the stand-off, so that all mechanical pressures (twisting and pushing) are applied to the outer lead. As a result, there is a problem to be solved such that bending or twisting occurs due to aging around the weak outer lead, and eventually cutting occurs.

[Object of the Invention] An object of the present invention is to realize a semiconductor package having a structure in which outer leads are hardly bent even when a mechanical pressure is applied.

Another object of the present invention is to realize a surface-mount type semiconductor package capable of improving the mechanical strength and durability of an outer lead terminal from a semiconductor device and the thermal characteristics of the package.

[0014]

According to the present invention, as a means for solving the above-mentioned problems, a semiconductor package has a structure in which a plurality of projections having a height corresponding to a standoff are provided on a bottom surface. The semiconductor package described above is provided.

Further, the projection is characterized in that it has a truncated cone shape, a truncated pyramid shape, or a rectangular parallelepiped shape having a long side parallel to the resin-filled injection direction.

The package tray of the present invention is a package tray on which the semiconductor package is mounted.
It is characterized in that it has a concave portion in which the projection is fitted.

[Operation] According to the present invention, by providing a projection corresponding to a stand-off on the package itself, pressure and torsion can be received by the projection, and pressure can be dispersed.

Further, since the surface area can be increased by providing the projections, the thermal characteristics (radiation characteristics) can be improved.

Further, by forming the protruding portion into a truncated conical shape, a truncated pyramid shape, or a rectangular parallelepiped shape having a long side parallel to the resin enclosing injection direction, it is possible to suppress the generation of voids during resin encapsulation. .

The package tray on which the semiconductor package is placed is provided with a concave portion into which the projection is fitted, so that the semiconductor package can be firmly fixed even during transportation, so that the outer leads can be fixed during transportation. Can be prevented from bending.

[Differences from the Prior Art of the Present Invention] Conventionally, the stand-off of the external lead is made by the outer lead itself, and the package is formed by the outer lead between the board surface even after mounting by soldering or the like. Was supported through a space that was According to the present invention, since the package body has a protrusion having a height corresponding to the stand-off of the surface mount type outer lead, the package can be supported by both the outer lead and the protrusion on the bottom surface of the package, and the load can be distributed. .

According to the present invention, a plurality of protrusions corresponding to the height of the standoff are provided on the bottom surface of the semiconductor package of the surface mount. As for the manufacturing method, the conventional mold used at the time of resin encapsulation,
It is easily possible if processing is applied to a place corresponding to the projection.

According to the present invention, since the load on the outer leads is reduced, an H / S (heat sink) can be provided even in an inexpensive plastic surface mount type LSI.

Particularly, in the case of H / S (heat sink),
In some cases, it is simply fixed to the upper part of the package with resin, but in some cases, it is even possible to screw it to the housing. In such a case, a vertical force is applied to the package, and conventionally, the force is directly transmitted to the pins (outer leads) of the LSI, causing pin bending and pin breakage.

[0025]

【Example】

Embodiment 1 FIG. 1 is a structural view showing both a plan view and a side view of this embodiment.

In FIG. 1, a package 1 is used in this embodiment.
Has six protrusions 2 on the bottom surface of the mounting board 7 and is mounted on the surface of the mounting board 7. The standoff 3 is created by the outer lead 6 and the bottom surface of the package 1. The protrusion 2 has the shape of a truncated cone, and its height is the same as the height of the standoff 3 formed by the package 1 and the outer lead 6.

Usually, the resin encapsulation enters from one corner of the package 1 and is extruded from a diagonal corner. Therefore, by adopting a truncated cone structure instead of a columnar structure as in the present embodiment, it is possible to avoid discontinuity in the resin encapsulation speed around the protruding portion 6 when encapsulating the package with resin. Accordingly, generation of holes (voids) on the package surface can be minimized.

The protruding portion 2 thus produced, together with the outer leads 6, receives the load from the surface of the package 1 in a dispersed manner.

[Embodiment 2] FIG. 2 is a structural diagram showing both a plan view and a side view of this embodiment.

Referring to FIG. 2, a second embodiment of the present invention will be described. In this embodiment, the package 11 has six protrusions 12 on the bottom surface. The protrusion has the shape of a truncated pyramid, and its height is the height of the standoff 13 of the package 11.
Of the same height.

In this example, the shape of the protruding portion 12 is a truncated pyramid. However, as described in the first embodiment, it is necessary to reduce the injection speed in order to avoid voids during resin encapsulation.

Embodiment 3 FIG. 3 is a structural diagram showing both a plan view and a side view of this embodiment.

Referring to FIG. 3, a third embodiment of the present invention will be described. In this embodiment, the package 21 has four protrusions 22 on the bottom surface. The protrusion 22 has a shape close to a rectangular parallelepiped, and the height is the same as the height of the standoff 23 of the package 21.

Although various shapes and arrangements are conceivable, the point is that the shape and the angle are small with respect to the resin enclosing and injection direction. For example, as shown in FIG. Are preferably arranged such that the long side direction is parallel to the resin-filled injection direction.

In addition, in the case of this method, since a wide contact surface with the surrounding atmosphere is formed, if a large number of the heat radiation fins are provided, the structure becomes the same as that of the radiation fin, and the radiation effect (thermal characteristics) can be improved.

[Embodiment 4] Further, considering the case of transporting a package of a semiconductor integrated circuit, if a recess having the same shape as the projecting portion of the package is formed on the package tray,
Since the outer leads cannot be easily moved because they are fitted to each other, it is possible to prevent the outer leads from being bent during transportation.

[0037]

As described above, according to the present invention, not only the outer leads but also the protrusions on the bottom surface of the package are provided as means for supporting the package of the semiconductor integrated circuit while maintaining the standoff. This makes it possible to withstand the load from the upper part of the package.

Also, the thermal characteristics (generally lowering the thermal resistance of the case) are improved by increasing the surface area by providing the projections.

Further, considering the case of transporting a package of a semiconductor integrated circuit, if the package tray is provided with a recess having a shape similar to that of the projecting portion of the package, it cannot be easily moved by being fitted to each other. Of the outer lead can be prevented.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a semiconductor package according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a semiconductor package according to a second embodiment of the present invention.

FIG. 3 is a structural diagram of a semiconductor package according to a third embodiment of the present invention.

FIG. 4 is a structural diagram of a conventional semiconductor package.

[Explanation of symbols]

 1,11,21 Package 2,12,22 Projection 3,13,23 Standoff 4,14,24,6,16,26 Outer lead 7 Mounting board

Claims (5)

[Claims] 1. A semiconductor package having a plurality of projections on a bottom surface having a height corresponding to a standoff. 2. The semiconductor package according to claim 1, wherein the protrusion has a truncated cone shape. 3. The semiconductor package according to claim 1, wherein the protrusion has a truncated pyramid shape. 4. The semiconductor package according to claim 1, wherein the protrusion has a rectangular parallelepiped shape, and a long side direction of the rectangular parallelepiped is arranged in parallel with a resin enclosing injection direction. 5. A package tray on which the semiconductor package according to claim 1 is mounted, the package tray having a concave portion into which the protrusion is fitted.