JPH1056278A - Mounting structure for large power semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure for a large power semiconductor element wherein high heat radiation is obtained at low cost. SOLUTION: Relating to the implementation structure, a circuit substrate 2 to which a large power semiconductor element 1 is connected by a flip chip method is connected to the main substrate 3. Since the semiconductor element 1 and the main substrate 3 are, through a heat conductor 4, thermally connected together, the heat generated at the semiconductor element 1 is transferred to the main substrate 3 through the circuit substrate 2, and at the same time, it is transferred to the main substrate 3 through the heat conductor 4 for heat radiation, further, the heat transferred from the semiconductor element 1 to the heat conductor 4 can be radiated from the heat conductor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure suitable for connecting a circuit board to which a high-power semiconductor element is connected to a main board.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional mounting structure of this kind. In the figure, 101 is a high power semiconductor element such as a GaAs semiconductor, 101a is a bump provided on the lower surface of the semiconductor element 101, 102 is a sealing resin, 103 is a circuit board, 104 is a main board, and 104a is a main board 104
Is a ground electrode provided on the upper surface of. Semiconductor element 1
01 is connected to the circuit board 103 by a flip chip method, and the circuit board 103 is connected to the main board 10 by a reflow method.
4 is connected.

In this mounting structure, heat generated in the semiconductor element 101 is transmitted to the circuit board 104 through the bumps 101a and the sealing resin 102, and is transmitted from the circuit board 104 to the main board 105 through the ground electrode 104a to radiate heat.

[0004]

However, since a high-power semiconductor device such as a GaAs semiconductor generates a large amount of heat inside the device, if the heat radiation characteristics determined by the mounting structure itself is low, the temperature of the device locally increases. Rises, causing a problem such as malfunction or destruction.

In order to solve this problem in the conventional mounting structure shown in FIG. 6, a material having high thermal conductivity is used for the circuit board 103, or the contact area of the bump 101a is increased to improve the heat radiation characteristics. Although it is necessary to use such an approach, there is a problem that the cost is increased due to a limitation of the substrate forming technology and the bump forming technology, and heat radiation characteristics as expected cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mounting structure of a high-power semiconductor element which can obtain high heat radiation characteristics at low cost.

[0007]

In order to achieve the above object, the present invention provides a high power type semiconductor device comprising a circuit board to which a high power type semiconductor device is connected by a flip-chip method and connected to a main substrate. The main feature of the mounting structure is that the semiconductor element and the main substrate are thermally connected via a heat conductor.

According to the mounting structure of the high power type semiconductor device according to the present invention, the heat generated in the semiconductor device is transmitted to the main substrate via the circuit board and simultaneously to the main substrate via the heat conductor. The heat can be transmitted and dissipated. Moreover, heat transmitted to the heat conductor can be radiated from the heat conductor.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows a mounting structure according to a first embodiment of the present invention. In the figure, 1 is GaAs
a high-power semiconductor element such as an s-semiconductor;
2 is a circuit board, 3 is a main board, 3a is a ground electrode provided on the top face of the main board 3, 3b is a connection electrode provided on the top face of the main board 3, and 4 is a heat electrode. It is a conductor.

The heat conductor 4 is made of a metal material having high heat conductivity such as stainless steel or aluminum, and has a rectangular top plate 4a slightly larger than the top surface of the circuit board 2 and four sides of the top plate 4a. It is configured in a box shape with a lower surface opening from a total of four side plate portions 4b extending downward from. In addition, at least the inner surfaces of two opposing side plates 4b of the four side plates 4b abut on the upper surface end of the circuit board 2 to define the positional relationship between the heat conductor 4 and the circuit board 3. A protrusion 4c is provided. Further, a flange portion 4d for stably supporting the heat conductor 4 on the main board 3 is provided along a lower side of the side plate portion at a lower end of at least two opposing side plate portions 4b among the four side plate portions 4b. Is provided.

Here, a procedure for constructing the mounting structure shown in FIG. 1 will be described. First, the semiconductor element 1 is mounted at a predetermined position on the circuit board 2, and the semiconductor element 1 and the circuit board 2 are connected by a flip chip method. If the bump itself cannot be used as a bonding material, a bonding material such as cream solder is applied to the circuit board 2 before mounting the element. Further, a gap between the semiconductor element 1 and the circuit board 2 is sealed with a resin (not shown) as necessary.

Next, after applying a thermally conductive adhesive 5 to the upper surface of the semiconductor element 1 on the circuit board 2, the upper surface of the semiconductor element 1 is placed on the top plate of the heat conductor 4 via the adhesive 5. The circuit board 2 is inserted into the heat conductor 4 so as to be in contact with the inner surface of the portion 4a, and the semiconductor element 1 and the heat conductor 4 are connected.

As a result, the circuit board 2 has its upper surface and 4
The side surface is completely covered by the heat conductor 4, and the lower surface of the circuit board 2 and the lower surface of the flange 4d are located in the same plane. Since the clearance between the upper surface of the semiconductor element 1 and the inner surface of the top plate 4a of the heat conductor 4 can be managed by bringing the circuit board 2 into contact with the protrusion 4c, the circuit board 2 is inserted into the heat conductor 4. At this time, the adhesive 5 is crushed and runs down, or the adhesive 5
There will be no gap between the top plate 4a and the inner surface of the top plate 4a.

Next, the circuit board 2 with the heat conductor 4 is mounted on the main board so that the circuit board 2 is located on the ground electrode 3a and the flange 4d of the heat conductor 4 is located on the connection electrode 3b. The circuit board 2 and the heat conductor 4 are connected to the main board 3 by a reflow method. Thus, a mounting structure as shown in FIG. 1 is obtained.

According to the mounting structure of the present embodiment, the heat generated in the semiconductor element 1 is transmitted to the main board 3 via the bump 1a and the circuit board 2, and at the same time, is transferred via the adhesive 5 and the heat conductor 4. Then, the heat can be transmitted to the main board 3 and radiated. In addition, heat transmitted from the semiconductor element 1 to the heat conductor 4 can be radiated from the heat conductor 4 that comes into contact with air over a wide area.

That is, the heat generated in the semiconductor element 1 can be effectively radiated by using the two heat radiation paths, which leads to an increase in cost such as a change in the material of the circuit board 2 and an increase in the contact area of the bump 1a. Without adopting the method, the heat radiation characteristics of the mounting structure itself can be remarkably improved as compared with the conventional one.

The flange 4d provided on the side plate 4b of the heat conductor 4 is not always necessary, and the lower end of the side plate 4b may be brought into contact with the connection electrode 3b for connection. Further, the circuit board 2 and the heat conductor 4 may be connected to the main board 3 with a heat conductive adhesive. In this case, the connection electrode 3 b may be eliminated from the main board 3. Furthermore, if a metal film is provided on the upper surface of the semiconductor element 1,
It is also possible to use solder for connecting the semiconductor element 1 and the heat conductor 4.

[Second Embodiment] FIG. 2 shows a second embodiment of the present invention.
2 shows a mounting structure according to the embodiment. This embodiment is different from the first embodiment in that the top plate 6 of the heat conductor 6
a is provided with an opening 6e smaller than the upper surface shape of the component 1, except that the top plate, side plate, protrusion, and flange of the heat conductor 6 are denoted by reference numerals 6a, 6b, 6c, and 6d. Has the same configuration as that of the first embodiment, and the mounting structure construction procedure is also the same as that of the first embodiment.

According to the mounting structure of the present embodiment, the heat generated in the semiconductor element 1 is radiated directly into the air from the opening 6e provided in the top plate 6a of the heat conductor 6, thereby further improving the heat radiation characteristics. Can be. Other operations and effects are the same as those of the first embodiment.

Although the adhesive 5 is applied to the upper surface of the semiconductor element 1, the circuit board 2 is inserted into the heat conductor 6, but after the circuit board 2 is inserted into the heat conductor 6, The connection may be made by supplying the adhesive 5 from an opening 6 e provided in the top plate 6 a of the heat conductor 6. In addition, the semiconductor element 1
If a metal film is provided on the upper surface of the semiconductor device 1, solder can be used to connect the semiconductor element 1 and the thermal conductor 4, and solder can be supplied from the opening 6e provided in the top plate 6a.
Further, the flange 6d provided on the side plate 6b of the heat conductor 6 is not always necessary, and the lower end of the side plate 6b may be connected to the connection electrode 3b. Furthermore, the circuit board 2 and the heat conductor 6 may be connected to the main board 3 with a heat conductive adhesive. In this case, the connection electrode 3b may be eliminated from the main board 3. .

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention.
2 shows a mounting structure according to the embodiment. This embodiment is different from the first embodiment in that the top plate 7a of the heat conductor 7 is formed smaller than the top surface of the circuit board 8 and the projection 7c is provided on the outer surface of the side plate 7c. A point provided with an insertion piece 7d penetrating the circuit board 8 at the lower end of the portion 7c;
Is provided with a through hole 8a into which the insertion piece 7d of the heat conductor 7 is inserted, and the configuration is the same as that of the first embodiment except that the position and shape of the connection electrode 3b of the main board 3 are changed. It is.

Here, the procedure for constructing the mounting structure shown in FIG. 3 will be described. First, the semiconductor element 1 is mounted on a predetermined position of the circuit board 8, and the semiconductor element 1 and the circuit board 8 are connected by a flip chip method. If the bump itself cannot be used as a bonding material, a bonding material such as cream solder is applied to the circuit board 8 before mounting the element. Further, a gap between the semiconductor element 1 and the circuit board 8 is sealed with a resin (not shown) as necessary.

Next, after applying a thermally conductive adhesive 5 to the upper surface of the semiconductor element 1 on the circuit board 8, the upper surface of the semiconductor element 1 is placed on the top plate of the heat conductor 7 via the adhesive 5. The insertion piece 7d of the heat conductor 7 is inserted into the circuit board 8 so as to be in contact with the inner surface of the portion 7a.
The semiconductor element 1 and the heat conductor 7 are connected to each other through the through hole 8a.

As a result, the semiconductor element 1 is completely covered with the heat conductor 7 on the upper surface and the four side surfaces.
The lower end of the insertion piece 7d is exposed from the lower surface of the circuit board 8. By contacting the circuit board 8 with the protrusion 7c, the semiconductor element 1
Can be managed between the upper surface of the heat conductor 7 and the inner surface of the top plate portion 7a of the heat conductor 7, so that when the semiconductor element 1 is inserted into the heat conductor 7, the adhesive 5 is crushed and flows down. There is no possibility that a gap is generated between the inner surface of the top plate 7a and the top plate 7a.

Next, the circuit board 8 with the heat conductor 7 is positioned so that the circuit board 2 is positioned on the ground electrode 3a and the exposed portion of the insertion piece 7d of the heat conductor 7 is positioned on the connection electrode 3b. Is mounted on the main board 3, and the circuit board 8 and the heat conductor 7 are connected to the main board 3 by a reflow method. Thus, a mounting structure as shown in FIG. 3 is obtained.

According to the mounting structure of the present embodiment, even when the circuit board 8 is too large to be accommodated in the heat conductor 7, two heat radiation paths can be provided as in the first embodiment. Other operations and effects are the same as those of the first embodiment.

The circuit board 8 and the heat conductor 7 may be connected to the main board 3 with a heat conductive adhesive. In this case, the connection electrodes 3b are removed from the main board 3. Is also good.

[Fourth Embodiment] FIG. 4 shows a fourth embodiment of the present invention.
2 shows a mounting structure according to the embodiment. This embodiment is different from the first embodiment in that a top plate 9 of the heat conductor 9 is provided.
a is provided with an opening 9e larger than the upper surface shape of the semiconductor element 1, and the inner surface of the opening 9e is joined to the side surface of the semiconductor element 1 via an adhesive 5, and the top plate and the side plate of the heat conductor 9 The configuration is the same as that of the first embodiment except that the reference numerals 9a, 9b, 9c and 9d are assigned to the projections and the flanges.

Here, a procedure for constructing the mounting structure shown in FIG. 4 will be described. First, the semiconductor element 1 is mounted at a predetermined position on the circuit board 2, and the semiconductor element 1 and the circuit board 2 are connected by a flip chip method. If the bump itself cannot be used as a bonding material, a bonding material such as cream solder is applied to the circuit board 2 before mounting the element. Further, a gap between the semiconductor element 1 and the circuit board 2 is sealed with a resin (not shown) as necessary.

Next, the circuit board 2 is inserted into the thermal conductor 9 so that the upper surface of the semiconductor element 1 on the circuit board 2 is exposed from the opening 9e of the thermal conductor 9, and then the inner surface of the opening 9e is removed. The heat conductive adhesive 5 is supplied to the gap between the side surface of the component 1 and the semiconductor element 1 and the heat conductor 9 are connected.

Thus, the circuit board 2 has its upper surface and 4
The sides are completely covered by the heat conductor 9 and the semiconductor element 1
Is exposed from the opening 9e of the heat conductor 9.

Next, the circuit board 2 with the heat conductor 9 is mounted on the main board so that the circuit board 2 is located on the ground electrode 3a and the flange 9d of the heat conductor 9 is located on the connection electrode 3b. 3, the circuit board 2 and the thermal conductor 9 are connected to the main board 3 by a reflow method. Thus, a mounting structure as shown in FIG. 1 is obtained.

According to the mounting structure of the present embodiment, the heat generated in the semiconductor element 1 can be directly radiated into the air from the opening 9e provided in the top plate 9a of the heat conductor 9 to further improve the heat radiation characteristics. it can. Further, since the upper surface height of the heat conductor 9 and the upper surface height of the semiconductor element 1 can be matched, the advantage that the thickness of the circuit board 3 with the heat conductor 9 does not increase even when the thickness of the semiconductor element 1 is large. There is. Other operations and effects are the same as those of the first embodiment.

The flange 9d provided on the side plate 9b of the heat conductor 9 is not always necessary. The lower end of the side plate 9b may be brought into contact with the connection electrode 3b for connection. Further, the circuit board 2 and the heat conductor 9 may be connected to the main board 3 with a heat conductive adhesive. In this case, the connection electrode 3b may be eliminated from the main board 3. Furthermore, if a metal film is provided on the side surface of the semiconductor element 1, it is possible to use solder to connect the semiconductor element 1 and the heat conductor 9.

[Fifth Embodiment] FIG. 5 shows a fifth embodiment of the present invention.
2 shows a mounting structure according to the embodiment. This embodiment is different from the first embodiment in that a plurality of semiconductor elements 1 connected to a circuit board 2 are covered with a single heat conductor 4, and other configurations and mounting structure construction procedures are similar to those of the first embodiment. This is the same as the first embodiment.

According to the mounting structure of the present embodiment, the heat generated in the plurality of semiconductor elements 1 can be transmitted to the main board 3 through the common heat conductor 4 and radiated. Other operations and effects are the same as those of the first embodiment.

The flange 4d provided on the side plate 4b of the heat conductor 4 is not always necessary. The lower end of the side plate 4b may be brought into contact with the connection electrode 3b for connection. Further, the circuit board 2 and the heat conductor 4 may be connected to the main board 3 with a heat conductive adhesive. In this case, the connection electrode 3 b may be eliminated from the main board 3. Furthermore, if a metal film is provided on the upper surface of the semiconductor element 1,
It is also possible to use solder for connecting the semiconductor element 1 and the heat conductor 4.

[0038]

As described in detail above, according to the present invention,
The heat generated in the semiconductor element can be transferred to the main board via the circuit board, and at the same time, can be transferred to the main board via the heat conductor to dissipate heat, and further transferred from the semiconductor element to the heat conductor. Heat can be dissipated from the heat conductor. In other words, it is possible to effectively dissipate the heat generated in the semiconductor element by utilizing the two heat dissipation paths, and to mount without using a method that leads to an increase in cost such as a change in the material of the circuit board or an increase in the contact area of the bumps. The heat radiation characteristics of the structure itself can be significantly improved as compared with the conventional structure.

[Brief description of the drawings]

FIG. 1 is a top view of a mounting structure according to a first embodiment of the present invention and a sectional view taken along line bb of FIG.

FIG. 2 is a sectional view of a mounting structure according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a mounting structure according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a mounting structure according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a mounting structure according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a mounting structure according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor element, 2 ... Circuit board, 3 ... Main board, 4 ...
Heat conductor, 5 ... adhesive, 6 ... heat conductor, 7 ... heat conductor,
8: circuit board, 9: thermal conductor.

Claims (5)

[Claims] 1. A mounting structure for a high-power semiconductor element comprising a circuit board, to which a high-power semiconductor element is connected by a flip-chip method, connected to a main board. A mounting structure for a high-power semiconductor element, which is thermally connected via 2. The mounting structure for a high-power semiconductor device according to claim 1, wherein the circuit board is connected to the main board by surface mounting. 3. A top plate having a heat conductor larger than the top surface of the semiconductor element and a side plate extending downward from an edge of the top plate, wherein the top plate is connected to the semiconductor element and the side plate is connected to the semiconductor element. The mounting structure for a high-power semiconductor device according to claim 1, wherein the mounting structure is connected to the main board from outside the circuit board. 4. A semiconductor device comprising: a top plate having a heat conductor larger than a top surface of the semiconductor element; and a side plate extending downward from the top plate and penetrating a circuit board, wherein the top plate is connected to the semiconductor element;
3. The mounting structure for a high-power semiconductor device according to claim 1, wherein a side plate portion penetrating the circuit board is connected to the main board. 5. The mounting structure for a high-power semiconductor device according to claim 3, wherein an opening for exposing the semiconductor device is provided in a top plate portion of the heat conductor.