JPH05114676A - Semiconductor device - Google Patents

Abstract

PURPOSE:To provide an inexpensive semiconductor device which does not cause its semiconductor elements to be damaged, has an excellent high-frequency characteristic, and can be easily manufactured. CONSTITUTION:After a transmission circuit element 27 is mounted on a substrate 21 formed by sticking a wiring board 22 and heat transferring plate 23 to each other by fixing a heat radiating terminal 31 to the projecting section 29 of the opening 28 of the plate 23 and soldering leads 32 to wiring 25 on the board 22, the plate 23 is thermally connected with an envelope 33 by bringing the plate 23 into contact with the envelope 33 when the substrate 21 is fixed in the envelope 33 with screws 36. As a result, the heat generated from the element 27 is transferred through a heat conducting route formed between the plate 23 connected with the terminal 31 and envelope 33 which is in contact with the plate 23 and has a low heat resistance and radiated to the outside from the external surface of the envelope 33. Therefore, an excellent high- frequency characteristic can be obtained without damaging semiconductor elements, etc., with an inexpensive constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device provided with a heat dissipation mechanism suitable for, for example, an optical transmission module.

[0002]

As is well known, in an optical transmission module or the like, an LD (Laser Diode) or an LED (Light Emitting Diode) is used.
It is necessary to drive a light emitting element such as e) by supplying a large current, and the heat generation in the optical transmitter is large. Therefore, the transmitter circuit element of the semiconductor element used in the optical transmitter has a heat dissipation mechanism for removing heat. On the other hand, higher speed transmission is required from the standpoint of the sophistication of information and the increase in the amount of information, and the heat generation in the optical transmission section is further increased. For example, the required current at 1 Mbit / sec was 5 mA to 10 mA, but when the speed is increased to 200 Mbit / sec, a current of about 200 mA will flow. Further, efficient heat removal is one of the issues for high-speed transmission.

Hereinafter, an example of a semiconductor device provided with a conventional heat dissipation mechanism will be described with reference to the drawings showing a main part of an optical transmission section of an optical transmission module.

First, a first example will be described with reference to FIG. FIG. 5 is a cross-sectional view showing a transmitter circuit element 2 of a semiconductor element on the upper surface of a wiring board 1 made of an insulating material, and a lead 4 of the transmitter circuit element 2 on a predetermined terminal portion of a wiring 3 provided on the wiring board 1. Are attached by soldering. Further, a heat sink 5 is attached to the upper surface of the package of the transmission circuit element 2 by adhesion so that the heat radiation fin portion is on the outer surface side. The circuit board 1 on which the transmission circuit element 2 is mounted is screwed by the screw 9 so that the transmission circuit element 2 is located in the recess 8 having the opening 7 of the envelope 6. At this time, the fins of the heat sink 5 are attached so as to be exposed to the outside from the opening 7.

With this structure, the heat of the transmission circuit element 2 is transferred mainly from the package of the transmission circuit element 2 to the heat sink 5, and is further radiated to the outside from the heat radiation fin portion. ..

Therefore, in order to realize a heat sink 5 which is as small as possible and has a high heat dissipation property, it is necessary to cut out a dedicated heat sink in accordance with the mounting situation, which is expensive, and the heat sink 5 has a transmitting circuit element. No. 2 is attached by adhesion, and it is necessary to strictly control the adhesion conditions in order to perform reliable attachment with high reliability, and the assembly process becomes complicated. Further, the heat dissipation fin portion of the heat sink 5 is exposed to the outside directly through the opening 7, and there is a possibility that dust may enter the inside of the opening 7 through the gap of the opening 7 depending on the use environment, and the heat sink 5 may be added from the outside. A force may be applied to the transmission circuit element 2 to damage it, and in some cases, it becomes a problem in terms of appearance.

The opening 7 is eliminated and the heat sink 5
The outer surface side of the enclosure is brought into contact with the inner surface of the envelope 6 so that the envelope 6 serves as a heat radiating portion to the atmosphere and is not exposed to the outside.
However, the external force applied to the envelope 6 is directly transmitted via the heat sink 5 to the transmission circuit element 2
There is a risk that it may be damaged by being added to.

Next, a second example will be described with reference to FIG. FIG. 6 is a cross-sectional view. In the wiring board 10, an insulating film 12 having a thickness of several tens of μm is formed on the upper surface of a base 11 made of a metal material.
A wiring 13 having a predetermined pattern is formed on the insulating film 12. Then, the transmission circuit element 2 of the semiconductor element is provided on the insulating film 12, and is attached by soldering the lead 4 to a predetermined portion of the wiring 13. Further, the heat dissipation terminal 14 of the transmission circuit element 2 is thermally connected to the wiring board 10 by bringing the tip end into contact with the base 11 of the wiring board 10 when the transmission circuit element 2 is attached to the wiring board 10. The wiring board 10 on which the transmission circuit element 2 is mounted is screwed by the screw 9 so that the transmission circuit element 2 is positioned in the recess 16 of the envelope 15.

With the above-described structure, the heat of the transmission circuit element 2 is mainly transferred from the heat dissipation terminal 14 to the wiring board 10.
Wiring substrate 1 on the base body 11 or via the insulating film 12
0 is transmitted to the base body 11, is transmitted to the envelope body 15 via a contact portion by screwing the base body 11 and the envelope body 15, and is radiated to the outside from the outer surface of the envelope body 15.

The heat radiation performed as described above is the first
Although it is much more efficient than the above example, the wirings 13 of the wiring board 10 must be provided via the insulating film 12, and the wirings 13 are formed on each side, so that the cross wiring and the wiring board 10 are formed. When both sides are connected and used, a connecting line must be additionally attached, which is expensive and complicated to assemble. On the other hand, since the wiring 13 is provided on the substrate 11 via the thin insulating film 12, the stray capacitance of the wiring 13 is large and the high frequency characteristics are poor, and the usable range is limited in the configuration of the optical transmission module. Has become.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the situation that the heat radiation effect is good but the cost is high, and the high frequency characteristics are deteriorated. The purpose of the present invention is as follows. It is an object of the present invention to provide a semiconductor device which is easy and inexpensive to manufacture and which does not cause damage to the semiconductor elements and components installed therein and has excellent high frequency characteristics.

[0012]

The semiconductor device of the present invention comprises:
An envelope formed of a heat conductive material, a substrate provided so as to stack a heat transfer plate and a wiring substrate on which wiring of a predetermined pattern is formed, and a heat dissipation terminal fixed to the heat transfer plate on the substrate and A semiconductor element attached to the wiring of the wiring board by fixing the leads to the wiring, and mounting the board so that the heat transfer plate is thermally connected to the inside of the envelope. It is characterized by being worn.

[0013]

In the semiconductor device configured as described above, the semiconductor element is fixed to the heat transfer plate with the heat radiation terminal and the lead is fixed to the wiring board on the substrate provided so as to stack the wiring board and the heat transfer plate. The heat is generated by the semiconductor element and the heat transfer plate is thermally connected to the enclosure so that it is attached to the inside of the enclosure. From the laminated heat transfer plate of the board to which the terminals are connected,
The heat transfer plates are sequentially transmitted through the heat conduction path having a small thermal resistance formed between the envelopes thermally connected to each other, and the heat is radiated to the outside from the outer surface of the envelope. Therefore, it can be constructed at low cost, and good high frequency characteristics can be obtained without damaging the semiconductor element or the like.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings showing the main part of an optical transmission section of an optical transmission module.

First, a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing a substrate on which a transmission circuit element is attached, and FIG. 2 is a cross-sectional view of an envelope on which the substrate is attached. The substrate in the drawing shows a cross section taken along the line AA of FIG. ing.

In the figure, a board 21 is a rectangular wiring board 2.
2 and the heat transfer plate 23 are bonded to each other. In the wiring board 22, a copper foil having a thickness of 200 μm or less, usually several tens of μm, is attached to the surface of a base body 24 formed of an epoxy resin using glass fiber as a base material or a phenol resin using paper as a base material. Then, the copper foil is etched by a known etching technique using a mask matching a predetermined pattern to form the wiring 25. The wirings 25 are formed on both sides of the wiring board 22, and the wirings on both sides are connected by the conductive members 26 provided in the through holes.

Further, the heat transfer plate 23 is a plate-shaped member made of a heat conductive material such as copper or copper alloy having a thickness of 100 μm or more and usually 1 mm or less, and has a central portion larger than the shape of the transmission circuit element 27. A substantially rectangular opening 28 is formed, and a protrusion 29 is formed at the center of the long side of the opening 28.
The heat transfer plate 23 is processed by a known press process separately from the wiring board 22 and then bonded to the wiring board 22.
Alternatively, it is formed by pasting the wiring substrate 22 in advance and processing it into a predetermined shape by etching.

Further, in the transmission circuit element 27, a heat dissipation terminal 31 for guiding the heat generated by the built-in semiconductor chip 30 to the outside of the package is fixed to the convex portion 29 of the opening 28, and the heat dissipation terminal 31 and the heat transfer plate 23 are connected to each other. Are thermally connected. Further, the leads 3 connected to the input / output terminals of the semiconductor chip 30.
2 is soldered to a predetermined portion of the wiring 25.

The substrate 21 on which the transmission circuit element 27 is mounted is provided in the substrate 21 such that the transmission circuit element 27 is located in the recess 34 formed inside the envelope 33 made of a heat conductive material. The heat transfer plate 23 is screwed to a predetermined portion such that the heat transfer plate 23 is in contact with the inner surface of the envelope 33 by a screw 36 inserted through the mounting hole 35.

With this structure, the heat generated by operating the device is transferred from the semiconductor chip 30 to the convex portion 29 of the heat transfer plate 23 by the heat dissipation terminal 31, and further transferred from the heat transfer plate 23. The heat plate 23 and the envelope 33 are transmitted to the envelope 33 via a portion where they are in contact with each other by screwing, and heat is radiated to the outside from the outer surface of the envelope 33.

Since the present embodiment is configured as described above, the heat of the semiconductor chip 30 passes from the heat radiating terminal 31 to the heat transfer plate 23, and further to the envelope 33 through a path having a high thermal conductivity to the outside. Heat is efficiently radiated from the outer surface of the envelope 33. The board 21 is formed by laminating a heat transfer plate 23 and a wiring board 22 formed of a copper foil in which the wiring 25 is directly attached to the base 24, and is easy to manufacture. Since it is formed on both the front and back sides, there is no need to attach cross wiring or connection lines afterwards, and assembly is easy and inexpensive.

Since the heat dissipation terminal 31 is connected to the envelope 33 via the heat transfer plate 23, the heat dissipation terminal 31 and the envelope 3 are connected.
3 and 3 can be stably held at the same potential by a connection with low impedance, and a good shield effect can be obtained without adding another component. Further, between the wiring 25 and the wiring 2
Since the distance between the heat transfer plate 5 and the heat transfer plate 23 in the heat transfer path can be made relatively large, the stray capacitance can be reduced and the high frequency characteristics can be improved.

In addition, an opening is formed on the outer surface of the envelope 33 so that the heat sink and the like are not exposed from the opening, and the force applied to the envelope 33 is applied to the transmitting circuit element 2.
Since it is not added to the external device 7, there is no possibility of dust invading into the envelope, appearance problems, and damage to the transmission circuit element 27.

Next, a second embodiment will be described with reference to FIGS. 3 and 4. In this embodiment, the mounting of the substrate on the envelope is limited to a position close to the side wall. FIG. 3 is a plan view showing the envelope to which the substrate is attached, and FIG. It is sectional drawing which shows the cross section of the BB arrow direction.

In the figure, a board 41 is a rectangular wiring board 4.
2 and the heat transfer plate 43 are attached to each other. Similar to the first embodiment, the wiring board 42 is formed by sticking a copper foil having a thickness of several tens of μm on the surface of a base 44 made of an insulating material and etching the copper foil into a predetermined pattern. Wiring 45 is provided. The wiring 45 is formed by connecting the front and back surfaces with a conductive member 46 penetrating the wiring board 42.

The heat transfer plate 43 is made of a copper plate having a thickness of 0.2 mm, and a substantially rectangular opening 28 larger than the shape of the transmission circuit element 27 is formed in the central portion.
A convex portion 29 is formed at the center of the long side of 8. Further, the edge portion of one side parallel to the long side of the opening 28 is the wiring board 42.
A rising portion 47 formed by being bent at a right angle is provided on the side opposite to the laminating surface. In this way, the rising portion 47
By forming the heat transfer plate 43, the distance from one side of the heat transfer plate 43 to the corresponding opening 28 is reduced from, for example, 2 mm to 0.5 mm. The heat transfer plate 43 is formed on the wiring board 4 by a known press process.
After the opening 28 and the rising portion 47 are processed separately from 2, the wiring board 42 is attached.

Further, in the transmitting circuit element 27, a heat radiating terminal 31 for leading out the heat generated by the built-in semiconductor chip 30 to the outside of the package is fixed to the convex portion 29 of the opening 28, and the heat radiating terminal 31 and the heat transfer plate 43 are provided. Are thermally connected. Further, the leads 32 connected to the input / output terminals of the semiconductor chip 30 are soldered to predetermined portions of the wiring 25.

Then, the substrate 41 on which the transmission circuit element 27 is mounted has the transmission circuit element 27 positioned in a predetermined recess 50 formed inside in proximity to the side wall 49 of the envelope 48 made of a heat conductive material. In addition, while the rising portion 47 of the heat transfer plate 43 is made to face the side wall 49, the substrate 41
The wiring board 42 is screwed so as to come into contact with the inner surface of the envelope 48 by a screw 52 inserted through a mounting hole 51 formed in the enclosure.

With this structure, the heat generated by operating the device is transferred from the semiconductor chip 30 to the convex portion 29 of the heat transfer plate 43 by the heat dissipation terminal 31, and is further transferred from the heat transfer plate 43. The heat is transmitted from the heat plate 43 to the envelope 48 via the screw 52 screwed to the envelope 48.
The heat is dissipated from the outer surface to the outside.

Since the present embodiment is constructed as described above, the same operation and effect as those of the first embodiment can be obtained, and the distance from the side wall 49 of the envelope 48 is restricted due to restrictions in mounting. Even when the substrate 41 is attached to the heat transfer plate 43 at a site where a heat transfer path having a minimum width of 2 mm cannot be secured, the rising portion 47 is provided so that the heat transfer path has a sufficient width. The substrate 41 and the like can be attached to every corner of the envelope 48. Further, the miniaturization of the envelope 48 and the highly functional dense packing can be realized.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications without departing from the scope of the invention.

[0032]

As is apparent from the above description, according to the present invention, a semiconductor element is fixed to a heat transfer plate and a heat radiating terminal is fixed to a substrate provided with a wiring board and a heat transfer plate laminated on each other, and a wiring board. Since the leads are fixedly attached to the substrate, and the substrate is attached so that the heat transfer plate is thermally connected to the envelope, the manufacturing is easy and inexpensive, and the interior is It is possible to obtain an effect that good high-frequency characteristics can be obtained without damaging a semiconductor element or a component that does not exist.

[Brief description of drawings]

FIG. 1 is a plan view showing a substrate on which a transmission circuit element according to a first embodiment of the present invention is attached.

FIG. 2 is a cross-sectional view of an essential part shown using a cross section taken along the line AA of FIG.

FIG. 3 is a plan view of an essential part showing a second embodiment of the present invention.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a cross-sectional view showing a first conventional example.

FIG. 6 is a sectional view showing a second conventional example.

[Explanation of symbols]

 21 ... Substrate 22 ... Wiring substrate 23 ... Heat transfer plate 25 ... Wiring 27 ... Transmitting circuit element 31 ... Heat dissipation terminal 32 ... Lead 33 ... Envelope

Claims (1)

[Claims] 1. An envelope formed of a heat conductive material, a substrate provided so as to stack a heat transfer plate and a wiring substrate on which a predetermined pattern of wiring is formed, and the heat transfer plate on the substrate. And a semiconductor element attached so as to fix the heat radiation terminal and the lead to the wiring of the wiring board, wherein the board has the heat transfer plate inside the envelope. A semiconductor device which is attached so as to be thermally connected to the semiconductor device.