JPH06268118A - Semiconductor device - Google Patents

Abstract

PURPOSE:To surely defoam a bonding agent sticking a circuit board to a heat radiating plate in a semiconductor device and, at the same time, simplify the assemblage of the semiconductor device. CONSTITUTION:A brazing material (bonding agent) 5 between the rear surface of a circuit board 1 and the projections 7 of a heat radiating plate 6 is defoamed by pressing the projections 7 against the rear surface of the board 1 in the necessary minimum areas corresponding to electronic parts 2 and 3 mounted on the front surface of the board 1 and the removed gas is discharged to the outside from the boundary between the board 1 and plate 6 through grooves 8. On the board 1, the electronic parts are mounted on the entire area of the board 1 so as to simplify the assembling process of this semiconductor device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a structure of a semiconductor device in which a heat radiating plate is attached to a circuit board on which electronic parts are mounted so that heat generated by the electronic parts on the board can be effectively radiated.

[0002]

2. Description of the Related Art A conventional semiconductor device is shown in FIG.
As shown in (B), the circuit board 1 having the opening 10 in the region where the semiconductor element package 2 is mounted is mounted on the heat dissipation plate 6 having the protrusions 7 having a height equal to or higher than the thickness of the board. (For example, Japanese Patent Laid-Open No. 3-1
No. 45146).

In the conventional case, the semiconductor package 2 and the projection 7 are directly brought into close contact with each other, and the heat generated from the semiconductor element 2 is effectively conducted to the heat dissipation plate 6 to be dissipated. A brazing material (adhesive) such as solder on the contact portion between the package 2 and the protrusion 7.
When 5 is applied, the bubbles generated inside the brazing material are
The semiconductor element package 2 is pressed against the protrusion 7 or rubbed against the protrusion 7 to remove bubbles from the brazing material 5.

Further, as shown in FIG. 4, the semiconductor element package 2, the semiconductor element 3 and other circuit components 4 are mounted on the circuit board 1 by a brazing material 5 such as solder, and heat is radiated to the entire back surface of the circuit board 1. There is a plate 6 attached. In the semiconductor device having this structure, the circuit board 1 is pressed against the heat dissipation plate 6 and rubbed to remove bubbles generated inside the brazing material.

[0005]

In the semiconductor device having the conventional structure shown in FIG. 3, the first step of adhering the circuit board to the heat sink 6 by the brazing material 5 such as solder and the semiconductor element package 2 are assembling steps. The second step of adhering the heat radiation plate 6 to the heat dissipation plate 6 by a brazing material such as solder, and the brazing material 5 such as a solder for the circuit board 1 and the terminals of the semiconductor element package and other circuit elements 4.
Therefore, the semiconductor device cannot be assembled without going through these three steps. In addition, since the heat sink with a large heat capacity must be heated in all the steps and it takes time to heat the heat sink, it takes time to manufacture and it is very difficult to mount parts by automation. It was

The conventional semiconductor device shown in FIG. 4 requires a two-step assembly process and is suitable for automation. However, a brazing material such as solder for adhering the circuit board 1 and the heat sink 6 to each other. There is a problem that bubbles are more likely to be generated in the inside of 5, and the larger the contact area between the substrate 1 and the heat dissipation plate 6, the more difficult it is to completely remove the bubbles.

An object of the present invention is to provide a semiconductor device having a structure in which the assembling process is simplified and the defoaming property of bubbles in the adhesive is improved.

[0008]

In order to achieve the above-mentioned object, a semiconductor device according to the present invention has a circuit board and a heat dissipation plate, and the heat dissipation plate is adhered to the back surface of the circuit board with an adhesive, Is a semiconductor device in which the heat generated by the electronic component is radiated by a heat radiating plate, and the circuit board is one in which the electronic component is mounted on the plate surface of a substrate made of a material having good thermal conductivity, and the heat radiating plate is a protrusion. And a groove, and the protrusion is made of a material having good thermal conductivity, is located directly below the electronic component on the circuit board to correspond to the electronic component, and is provided so as to rise upward individually for each electronic component,
It is adhered to the backside of the board corresponding to electronic parts,
Grooves are provided on the plate surface of the heat sink except for the protruding part, and the air bubbles deaerated around the protruding part from the uncured adhesive between the protrusion and the back surface of the substrate due to the pressing force when mounting the heat sink It is discharged to the outside and is filled with an adhesive after the bubbles are removed.

The grooves are provided in a stripe shape, a lattice shape, or a radial shape around the protrusions.

[0010]

The protrusions of the heat sink are located directly below the electronic components on the circuit board, and are individually provided to rise upward and are adhered to the back surface of the substrate on which the electronic components are mounted. It Air bubbles degassed from the uncured adhesive between the protrusions and the back surface of the substrate to the periphery of the protrusions are discharged to the outside of the bonding surface due to the pressing force when mounting the heat sink.

Since the protrusions are individually provided for each electronic component, the contact area between the heat sink and the back surface of the circuit board is reduced to the number of the protrusions corresponding to the electronic components mounted on the substrate, and the radiator plate is attached. The air pressure in the adhesive can be sufficiently removed by the pressing force applied at the time.

The bubbles degassed around the protrusions are exhausted to the outside of the bonding surface between the substrate and the heat sink by the groove, and the thermal conductivity between the substrate and the heat sink is not lowered. Since the circuit board has a structure in which all the components can be mounted on the substrate, the number of assembling steps can be reduced by mounting the components by automation.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1A is a plan view showing a semiconductor device according to a first embodiment of the present invention, and FIG. 1B is a plan view showing a heat dissipation plate used in the semiconductor device of the embodiment 1. C) is a cross-sectional view showing a state in which a circuit board and a heat sink are combined.

1A and 1C, the semiconductor device according to the first embodiment of the present invention has a circuit board 1 and a heat dissipation plate 6, and the heat dissipation plate 6 is attached to the back surface of the circuit board 1. The heat generated by the electronic components on the circuit board 1 is radiated by the heat radiating plate 6.

As shown in FIGS. 1A and 1C, the circuit board 1 includes a semiconductor element package 2 and a semiconductor element 3 as electronic components on a plate surface of a substrate made of a material having good thermal conductivity, for example, alumina. , And other circuit components 4 are mounted by a brazing material 5 such as solder. 9 is a needle terminal.

As shown in FIGS. 1B and 1C, the heat dissipation plate 6 is made of a material having good thermal conductivity for effectively dissipating heat.
For example, it is made of a metal such as aluminum or iron and has a protrusion 7 and a groove 8.

As shown in FIGS. 1 (B) and 1 (C), the protrusion 7 of the heat sink 6 is made of a material having good heat conduction, and is located right below the electronic components 2 and 3 on the circuit board 1. Then, the electronic components 2 and 3 are individually provided so as to rise upward, and are bonded to the back surface of the substrate corresponding to the electronic components 2 and 3 by a brazing material 5 such as solder as an adhesive.

In addition, the groove 8 of the heat dissipation plate 6 is shown in FIG.
As shown in (C), the protrusions 7 are provided radially around the protrusions on the plate surface of the heat dissipation plate 6 and receive the pressing force when the heat dissipation plate is attached.
Bubbles that have been degassed from the uncured brazing material 5 between the substrate and the back surface of the substrate are discharged to the outside of the bonding surface, and the brazing material 5 is filled after the defoaming of the bubbles.

For example, when a semiconductor element serving as a heating element has a bottom surface of 0.5 mm □, a circuit board thickness is 0.254 mm, and solder is used as a brazing material, the size of the protrusion is 1 to 2.5 mm.
The area is □ and the height is 0.1 to 0.2 mm.
The groove 8 has a width of 0.1 to 0.2 mm and a depth of 0.1 to 0.2 mm.
It is about 0.2 mm. The surface of the heat sink 6 is nickel-plated so that the circuit board 1 made of alumina or the like can be easily soldered.

Since the circuit board 1 has a structure in which the semiconductor package 2 and the semiconductor element 3 and other circuit components 4 can be mounted on the surface of the substrate, the circuit substrate 1 is assembled by mounting the components by automation.

A heat dissipation plate 6 is attached to the circuit board 1 assembled as described above by a brazing material 5. When the heat sink 6 is attached, the circuit board 1 is pressed against the heat sink 6 or rubbed against each other to remove air bubbles from the brazing material 5 so that the circuit board 1 and the heat dissipating plate 6 are joined together. 5
It is made to adhere by.

Here, in the present invention, the projection 7 provided on the heat sink 6 is provided with the semiconductor element package 2 on the circuit board 1.
Also, it is located directly below the semiconductor element, and is individually provided upright for each of these electronic components 2 and 3 and is bonded to the back surface of the substrate corresponding to the electronic components 2 and 3. Therefore, the contact area of the heat dissipation plate 6 with the back surface of the circuit board is reduced to the number of the projections 7 corresponding to the electronic components mounted on the board. Therefore, the pressing force applied to each projection 7 portion at the time of mounting the heat dissipation plate. Is a sufficient force to remove bubbles from the brazing material 5, and the bubbles can be surely removed by this pressing force.

Therefore, the air pressure contained in the brazing material 5 between the back surface of the substrate and the projection 7 is defoamed by the pressing force when the heat sink is attached and pushed out into the brazing material around the projection.

Further, according to the present invention, since the groove 8 extending from the peripheral portion of the protrusion to the outside of the bonding surface between the back surface of the substrate and the heat dissipation plate is provided, the bubbles pushed out to the peripheral portion of the protrusion radiate heat to the substrate by the groove 8. Exhausted outside the bonding surface of the board. After the bubbles are removed, the groove 8 is filled with the uncured brazing material 5 due to the pressing force when the heat sink is attached.

Further, in the present invention, since the components are mounted on the circuit board 1 using the entire surface of the circuit board, the assembly can be performed in two steps or less.

Further, in the present invention, since the substrate of the circuit board 1 and the protrusions 7 are made of a material having good thermal conductivity,
The heat of the electronic component generated on the substrate can be radiated from the heat radiating plate 6 through the substrate of the circuit board 1 and the protrusions 7, and the cooling efficiency of the electronic component can be improved.

(Embodiment 2) FIG. 2 is a plan view showing a heat dissipation plate used in a semiconductor device according to Embodiment 2 of the present invention.

In the present embodiment, as shown in FIG. 2, the grooves 8 are provided in the periphery of the protrusions in a grid pattern.
The bubbles degassed from the uncured brazing material 5 are exhausted to the outside of the bonding surface between the substrate and the heat dissipation plate. Also in this embodiment, the same effect as that of the first embodiment can be obtained. In this embodiment, the groove 8 is not nickel-plated. Further, even if the stripe-shaped grooves 8 are provided instead of the grid-shaped grooves 8, the degassed bubbles can be exhausted.

[0030]

As described above, according to the present invention, the protrusion of the heat sink is raised in correspondence with the heat-generating electronic component on the substrate,
Since the heatsink is attached to the backside of the board at the protrusions, the contact area between the heatsink and the circuit board can be reduced to the number of protrusions corresponding to the electronic components. Bubbles in the adhesive existing between the back surface of the substrate and the protrusions can be sufficiently removed.

Furthermore, the bubbles degassed around the protrusions are
The groove allows air to be exhausted to the outside of the bonding surface between the substrate and the heat radiating plate, and the heat conductivity between the substrate and the heat radiating plate can be increased so that heat generated by the electronic component can be radiated from the heat radiating plate.

Further, since the circuit board mounts the components by using the entire surface of the circuit board, the components can be mounted by automation, and the semiconductor device using the circuit board can be assembled in a small number of steps. .

Further, in the present invention, since the substrate and the projection of the circuit board are made of a material having good thermal conductivity, and the projection is adhered to the back surface of the board corresponding to the electronic component, the projection is generated on the board. The heat of the electronic component can be radiated from the heat radiating plate through the board and the protrusion of the circuit board, and the cooling efficiency of the electronic component can be improved.

[Brief description of drawings]

1A is a plan view showing a semiconductor device according to a first embodiment of the present invention, FIG. 1B is a plan view showing a heat dissipation plate used in the semiconductor device according to the first embodiment, and FIG. It is sectional drawing which shows the state which combined with the heat sink.

FIG. 2 is a plan view showing a heat dissipation plate used in a semiconductor device according to a second embodiment of the invention.

3A is a plan view showing a conventional example, and FIG. 3B is a sectional view of the same.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 circuit board 2 semiconductor element package 3 semiconductor element 4 circuit component 5 brazing material 6 heat sink 7 protrusion 8 groove

Claims (2)

[Claims] 1. A semiconductor device comprising a circuit board and a heat dissipation plate, wherein the heat dissipation plate is adhered to the back surface of the circuit board with an adhesive to dissipate heat generated by electronic components on the board by the heat dissipation plate. The board is one in which electronic components are mounted on the surface of a board made of a material having good thermal conductivity, the heat dissipation plate has protrusions and grooves, and the protrusions are made of material having good thermal conductivity. Corresponding to the electronic components on the circuit board, it is located directly underneath it, and each electronic component is set up to rise upward and is bonded to the back surface of the substrate corresponding to the electronic component. It is provided on the plate surface excluding the projecting part of the plate and receives the pressing force when mounting the heat sink and discharges the bubbles that have been degassed around the projecting part from the uncured adhesive between the projection and the back surface of the board. A semiconductor device characterized in that it is filled with an adhesive after the bubbles are removed. 2. The semiconductor device according to claim 1, wherein the groove is provided in a stripe shape, a lattice shape, or a radial shape around a protrusion.