JPH10326984A - Wiring board module - Google Patents

Abstract

(57) [Problem] To provide a wiring board module which can mount electronic components on both sides of an insulating substrate, has no heat stagnation, and is excellent in heat dissipation. An insulating substrate (1) on which an electronic component (2) is mounted on the front and back surfaces and at least a heat-generating electronic component (2 ') is mounted as an electronic component, and a heat transfer conductor provided inside the insulating substrate (1) A wiring board A including a layer 4, a heat-transfer via-hole conductor 5 for transferring heat generated from the heat-generating electronic component 2 ′ to the heat-transfer conductor layer 4, and the wiring board A is housed inside. In a wiring board module including a housing, a gap between a side surface of a wiring board A and an inner wall of the housing B is filled and interposed with a heat transfer material 8 made of a highly thermally conductive organic resin or metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hybrid IC.
The present invention relates to an improvement in a heat dissipation structure in a wiring board module including a wiring board having an exothermic electronic component mounted on an insulating substrate.

[0002]

2. Description of the Related Art Conventionally, there has been known a circuit board in which electronic components such as an IC and a resistance element are mounted on the surface of an insulating substrate made of ceramics or organic resin. Recently, with the increase in the precision of electronic components mounted on these circuit boards, for example, electronic components such as IC elements generate more heat when they operate,
Along with that, the heat adversely affects the operation of electronic components and other electronic components that generate heat,
A major issue is how to efficiently dissipate such heat.

Therefore, as a general heat radiation structure conventionally used, as shown in FIG. 4, an electronic component such as a hybrid IC 22 or a resistance element 23 is mounted on one surface of an insulating substrate 21 and the other surface is mounted on the other surface. Attach radiator 24,
The heat generated from the hybrid IC 22 is transmitted to a heat radiator 24 via a heat transfer via-hole conductor (hereinafter referred to as a thermal via) 25 provided in the insulating substrate 21, and is directly or joined to the heat radiator 24. It has a structure that is released from the radiation fins to the atmosphere.

[0004]

However, in a circuit board on which a hybrid IC or the like is mounted, an IC
Local stagnation of heat occurs in the mounting portion, and particularly when used for controlling an engine of an automobile or the like, the temperature of the IC portion sometimes becomes higher than the guaranteed operating temperature.

Recently, miniaturization of various circuit boards has been desired. However, in a conventional circuit board, electronic components cannot be mounted on both sides of the board because a heat radiator is attached to the back surface. In order to widen the mounting portion without deteriorating the heat radiation, it was necessary to increase the size of the substrate itself. Furthermore, in the case where both sides of the insulating substrate are electronic component mounting surfaces, no specific structure for efficiently dissipating heat generated from the mounted electronic components has been studied at present.

Accordingly, an object of the present invention is to suppress the heat generated from heat-generating electronic components in a wiring board module in which a wiring board having electronic components including heat-generating electronic components mounted on both sides of an insulating substrate is housed in a housing. And to provide a module with excellent heat dissipation.

[0007]

Means for Solving the Problems As a result of repeated studies on the above problems, the present inventors have found that in a wiring board having electronic components mounted on both sides of an insulating substrate, a conductive layer for heat transfer is provided inside the insulating substrate. Is provided, and the heat transfer conductor layer and the heat-generating electronic component are connected by a heat transfer via-hole conductor to transfer heat generated from the heat-generating electronic component to the heat transfer conductor layer. The entire wiring board is soaked, and when the wiring board is housed in the housing, a heat transfer material made of organic resin or metal with high thermal conductivity is interposed in the gap between the side surface of the wiring board and the housing. As a result, it has been found that efficient heat radiation can be achieved by transferring the heat of the wiring board from the side surface to the housing via the heat transfer material, and the present invention has been accomplished.

That is, a wiring board module according to the present invention comprises an insulating substrate having electronic components mounted on both sides thereof and a heat-generating electronic component mounted on at least one surface thereof, and a transmission board provided inside the insulating substrate. A wiring board comprising a heat conductor layer and a heat transfer via hole conductor for transferring heat generated from the heat-generating electronic component to the heat transfer conductor layer is housed and supported inside the housing. And a heat transfer material made of a highly heat conductive organic resin or metal is interposed in a gap between a side surface of the wiring board and the housing.

In general, the heat dissipation structure of a wiring board generally radiates heat from upper and lower surfaces of the wiring board through various heat transfer members. However, when the thickness of the wiring board is increased, the area of the side surface of the wiring board becomes so large that it cannot be ignored. Normally, when the wiring board is housed in the housing, a part of the wiring board is positioned and fixed to the supporting portion in the housing. Or simply installed so that the side surface of the wiring board is in contact with the inner wall of the housing.

However, in such an arrangement structure of the wiring board side surface and the housing inner wall, since heat having low thermal conductivity exists in the gap, heat is almost completely transferred from the wiring board side surface to the housing. Absent.

Therefore, according to the present invention, the gap between the side surface of the wiring board and the inner wall of the housing is interposed, preferably filled, with a high thermal conductive resin or metal, so that the heat from the side surface of the wiring board to the housing is filled. Is formed, and the heat in the wiring board can be radiated also from the side surface. At this time, by providing a heat transfer wiring layer formed on almost the entire surface of the wiring board from the heat generating electronic component via the heat transfer via hole conductor in the wiring board, the heat generating electronic component Heat can be guided to the side surface of the wiring board to achieve efficient heat radiation.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic sectional view of a wiring board A of the present invention, and FIG. 2 is a schematic sectional view of a module in which the wiring board A is housed in a housing B.

According to the present invention, various electronic components 2 are mounted on both the front surface and the rear surface of the insulating substrate 1. At least one heat-generating electronic component 2 'such as a hybrid IC is mounted. Other examples of such heat-generating electronic components include power transistors and power ICs.
Element, power resistance element and the like.

The heat-generating electronic component 2 ′ is mounted on the surface of the insulating substrate 1 via the metal conductor layer 3. Also,
According to the present invention, inside the insulating substrate 1, the heat transfer conductor layer 4 is formed over substantially the entire surface of the insulating substrate 1. The metal conductor layer 3 and the heat transfer conductor layer 4 are connected by a heat transfer via hole conductor 5, a so-called thermal via 5.

According to this structure, the heat-generating electronic component 2 '
Is transmitted to the metal conductor layer 3, further transmitted through the thermal via 5 to the heat transmission conductor layer 4. As a result, the heat generated from the heat-generating electronic component 2 'is transmitted to the entire wiring board without local stagnation, and is uniformed in the wiring board.

The insulating substrate 1 is made of an organic resin such as an epoxy resin or an insulating ceramic sintered body such as Al ₂ O ₃ , Si ₃ N ₄ or AlN.
In consideration of durability under severe use conditions, such as a circuit board for an automobile, it is desirable to use a ceramic sintered body. The metal conductor layer 3 and the heat transfer conductor layer 4
In view of the above function, it is preferable that the insulating substrate 1 itself be made of a high heat conductive metal such as copper, silver, gold, or an alloy containing them.
N, Si ₃ N ₄ and other ceramic sintered bodies, and when formed by simultaneous firing with these sintered bodies, W,
It is composed of a high melting point metal such as Mo. Recently, as in the case of glass ceramic materials, the sintering temperature is 800
Low-temperature fired ceramic materials of up to 1000 ° C. are known. When such a sintered body is used, a metal such as copper, gold, or aluminum can be used in forming a surface or internal metal layer. It is appropriate that each of the metal conductor layer 3 and the heat transfer conductor layer 4 has a thickness of 5 to 20 μm.

The metal conductor layer on the surface of the insulating substrate 1
For ceramic sintered bodies as described above, for example,
After printing and applying a copper paste, it can be formed by baking at 800 to 1100 ° C.

The metal conductor layer 3 and the heat transfer conductor layer 4
May function as a part of a wiring in a circuit in addition to the above function. For example, the heat transfer conductor layer 4 may function as a ground (ground) layer.

Further, when the insulating substrate 1 is made of a ceramic material, the thermal via 5 is formed by drilling a hole in an unfired green sheet with a microdrill or the like, and then filling the hole with a metal paste, and if necessary, a plurality of green pastes. After laminating the sheets, they can be formed by simultaneous firing with the green sheets. When the insulating substrate 1 is made of a ceramic sintered body such as Al ₂ O ₃ , AlN or Si ₃ N ₄ , the thermal via 5 also needs to be formed of a high melting point metal such as W or Mo. In the case of a glass ceramic material, it can be formed of copper, gold, aluminum, or the like. The thermal via 5 is suitably formed of a cylindrical body having a diameter of 0.1 to 0.3 mm.

On the surface of the insulating substrate 1, a wiring layer (not shown) electrically connected to form a circuit with electronic components mounted on the surface is formed.
May include an electronic component 2 mounted on the surface and an internal wiring layer (not shown) connected to a wiring layer on the surface, in addition to the heat transfer conductor layer 4.

On the other hand, as shown in FIG. 2, a supporting portion 6 or a supporting portion 7 for supporting the wiring board A is formed in the housing B for housing the wiring board A. The support portion 6 supports the end of the wiring board A, and usually has a step, and positions and supports the substrate with the step. The support section 7 supports the lower portion of the wiring board A when the wiring board A becomes large. In these supporting portions, the wiring board may be screwed to the housing in some cases.

According to the present invention, when the wiring board A is supported in the housing B, a gap is formed on the side surface between the housing B and the wiring board A. The heat transfer members 8 and 9 made of a high heat conductive organic resin or metal are interposed in a gap between the side surface of the housing and the housing B. As the high thermal conductive organic resin to be used, a resin having a thermal conductivity of 1 W / m · K or more, such as a silicone resin, an acetylene resin, and a pyrrole resin, is desirable. Examples of the metal include copper, silver, gold, and alloys containing them, and the metal is desirably a metal having a fluidity at a relatively low temperature, such as solder or a brazing material such as silver brazing.

In the present invention, as a specific structure in which the heat transfer material is interposed, as shown in FIG. And interposed. Further, on the side surface of the wiring board A other than the support portion, a gap between the wiring board A and the housing B is filled with a heat transfer material 9 and interposed.

In order to interpose the heat transfer materials 8 and 9 in the gap, for example, after the wiring board A is stored and supported in the housing B,
After filling the gap between the side surface of the wiring board A and the housing B with the softened high heat conductive organic resin, the resin is cooled or heated to be cured, or the molten solder is poured into the gap.

As another method, as shown in FIG. 3, a conductive material made of a high thermal conductive resin or metal is placed on the side surface of the wiring board A or the place where the side surface of the wiring board A of the housing B is installed. When the heating material 10 is attached in advance or softened resin or metal is applied to the surface, and the wiring board A is stored and supported in the housing B, the wiring board A is connected to the housing B via the heat transfer material 8. What is necessary is just to press-contact and support.

According to the present invention, the air having low thermal conductivity usually exists in the gap between the side surface of the wiring board A and the housing B, but it is made of resin or metal having high thermal conductivity. By interposing the heat transfer material, the heat transferred into the wiring board A by the heat transfer conductor layer 4 provided in the wiring board A is transmitted from the side surface of the wiring board A via the heat transfer material 8. Heat can be transferred to the housing B.

From this point, for example, as shown in FIG. 3, the end surface of the insulating substrate A is ground to expose the heat conductive conductor layer 4 inside the insulating substrate A to the side surface, and the heat conductive material 10 Is provided so as to be in contact with each other, the heat transfer from the heat transfer conductor layer 4 to the heat transfer material can be improved. Further, it is desirable that the housing B to which heat is transmitted via the heat transfer material be formed of a resin or the like having high thermal conductivity or a metal.

Further, in the wiring board module according to the present invention, in addition to the above-described heat dissipation structure, another heat dissipation structure can be used together. For example, as shown in FIG.
A heat radiation fin 11 made of a metal is provided in a part of the metal conductor layer 3, a metal conductor layer 3 on which the heat-generating electronic component 2 ′ is mounted is extended, and thermally connected by a heat spreader 12.
The space formed between the radiation fins 11 and the wiring board A can be filled with a thermally conductive resin or gel.

In order to confirm the effect of the present invention, six layers of green sheets made of alumina are prepared, and a tungsten paste is used as a heat transfer conductor layer on the fourth layer to have a thickness of 20 μm over almost the entire surface. Printed as follows. The diameter of the first and second green sheets is 0.2 mm by a micro drill at the position where the hybrid IC is mounted.
Eight mm via holes were drilled and filled with tungsten paste.

After the green sheets are aligned and laminated, they are fired in a non-oxidizing atmosphere at 1700 ° C. to form a heat transfer conductor layer 4 and a heat transfer via hole conductor (thermal via) 5. A 2 mm substrate was produced.

Thereafter, a copper paste was applied to the IC element mounting portion and baked at 900 ° C. to form a metal conductor layer 3 having a thickness of 10 μm. Then, the hybrid IC element was mounted on the surface of the metal conductor layer 3, and electronic components such as resistance elements were mounted and mounted on both surfaces of the insulating substrate, thereby producing a wiring board A.

Then, a housing B made of an aluminum alloy
After the wiring board A is stored and supported therein, a silicone resin or a solder alloy (P
b40% -Sn60%).

With respect to the wiring board module manufactured as described above, the IC mounted on the board was operated and the temperature of the hybrid IC itself was measured. in the case of,
In the case of a solder alloy of 3 ° C., a temperature decrease of 5 ° C. was confirmed, and the effect of the heat transfer material was confirmed.

When the heat transfer conductor layer 4 is not formed in the wiring board A, even if the heat transfer material is provided, only a cooling effect of about 1 ° C. or less is obtained. It was also confirmed that 5 was essential.

[0035]

As described in detail above, according to the wiring board module of the present invention, electronic components can be mounted on both sides of an insulating substrate, and when a heat-generating electronic component such as a hybrid IC is mounted. Local stagnation of heat can be eliminated, the heat can be uniformed over the entire wiring board, and heat can be efficiently radiated to the housing. As a result, the reliability of the wiring board A can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an embodiment of a wiring board A according to the present invention.

FIG. 2 is a schematic sectional view of a wiring board module of the present invention in which the wiring board A of FIG.

FIG. 3 is a cross-sectional view of a main part for describing another interposed structure of the heat transfer material according to the present invention.

FIG. 4 is a schematic cross-sectional view illustrating a heat dissipation structure of a conventional wiring board.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 electronic component 2 ′ heat-generating electronic component 3 metal conductor layer 4 heat transfer conductor layer 5 heat transfer via hole conductor (thermal via) 6, 7 support portion 8, 9, 10 heat transfer material A wiring board B case body

Claims (1)

[Claims] An insulating substrate having electronic components mounted on both sides thereof and a heat-generating electronic component mounted on at least one surface; a heat transfer conductor layer provided inside the insulating substrate; A wiring board comprising a heat transfer via hole conductor for transferring heat generated from the conductive electronic component to the heat transfer conductor layer, a wiring board module housed and supported inside a housing, A wiring board module, wherein a heat transfer material made of a highly thermally conductive organic resin or metal is interposed in a gap between a side surface of the wiring board and the housing.