JPH05327249A - Electronic circuit module and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an electronic circuit module having superior heat radiating characteristics and a high heat-resisting reliability. CONSTITUTION:An electronic circuit module is made up of: a circuit board 12 substantially at the center of which an opening or a notch 12c is formed; a heat radiating board 20 fixed to a first surface of the circuit board; circuit components 16 mounted on a second surface of the circuit board 12 which require heat radiation, in which the body of the components is fixed to the heat radiating board 20 within the opening or notch 12c of the circuit board 12; and circuit components 14 mounted on the second surface of the circuit board 12 which do not require heat to be radiated away.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit module having circuit components that require heat dissipation and a method for manufacturing the same.

In recent years, with the downsizing, weight reduction, and high performance of devices such as communication devices, in these devices, electronic components are mounted on a small circuit board for a specific circuit to form an electronic circuit module, There is a tendency to mount this electronic circuit module on the motherboard of the device. When this kind of electronic circuit module has a circuit component that requires heat dissipation, a means for heat dissipation is indispensable in the electronic circuit module, and an electronic circuit that considers heat generation in such a circuit component is required. The structure of the module and the manufacturing method thereof are being sought.

[0003]

2. Description of the Related Art Conventionally, as an electronic circuit module having a circuit component that requires heat dissipation, as shown in FIG. 7, an insulating layer 4 is formed on a heat dissipation plate 2 made of aluminum or the like by a method such as print coating, and insulation is performed. It is known that the layer 4 is used as a circuit board and the circuit components 6, 8 and the lead terminals 10 are mounted on the circuit board.

Of the circuit components 6 and 8, the circuit component 6 is a circuit component such as a power transistor that requires heat dissipation, and the circuit component 8 is a circuit component such as a chip resistor that does not require heat dissipation.
The lead terminal 10 is formed by bending a wire into an L-shape, and the lead terminal 10 is mounted by soldering one side of the L-shape to a conductor pattern (not shown) on the insulating layer 4.

[0005]

In the conventional electronic circuit module described with reference to FIG. 7, the insulating layer 4 made of epoxy resin or the like is interposed between the circuit component 6 requiring heat dissipation and the heat dissipation plate 2. Therefore, there is a problem that the heat dissipation characteristic is inferior.

Further, since the insulating layer 4 is formed on the entire surface of the heat dissipation plate 2, there is a problem that the heat resistance reliability is deteriorated due to the difference in the coefficient of linear thermal expansion between the heat dissipation plate 2 and the insulation layer 4. An object of the present invention is to provide an electronic circuit module having good heat dissipation characteristics and high heat resistance and a manufacturing method thereof.

[0007]

An electronic circuit module according to the present invention includes a circuit board having an opening or a notch formed at a substantially central portion thereof, and a heat dissipation plate fixed to a first surface of the circuit board.
A circuit component which is mounted on the second surface of the circuit board and whose body is fixed to the heat dissipation plate in the opening or notch of the circuit board and which requires heat dissipation is surface-mounted on the second surface of the circuit board. And circuit components that do not require heat dissipation.

The method of manufacturing an electronic circuit module according to the present invention comprises the first step of surface-mounting a circuit component that does not require heat radiation on the first surface of a circuit board having an opening or a notch formed at a substantially central portion thereof. A second step of mounting a circuit component requiring heat radiation on the first surface of the circuit board so that the component faces the opening or notch, and the first surface and the second surface of the circuit board at the edge of the circuit board. A third step of arranging a plurality of lead terminals so as to project from the surface, and the first and second steps described above.
And, after the third step, a heat dissipation plate having a plurality of pores formed at the edge is brought into close contact with the second surface of the circuit board so that the lead terminals are located in the pores, and the heat dissipation is required. A fourth step of filling the resin into the openings or notches of the circuit board and the pores of the heat dissipation plate and solidifying the resin while the circuit component is in close contact with the heat dissipation plate.

[0009]

According to the present invention, the circuit component mounted on the circuit board and requiring heat dissipation is directly fixed to the heat sink through the opening or notch formed at the approximate center of the circuit board. The characteristics are good. Further, since the circuit board in which the opening or notch is partially formed is fixed to the heat dissipation plate, it is possible to disperse the generation of thermal stress due to the difference in the coefficient of linear thermal expansion between the heat dissipation plate and the circuit board, Heat resistance reliability is improved as compared with a conventional electronic circuit module in which an insulating layer is formed on the entire surface of the heat sink.

[0010]

EXAMPLES Examples of the present invention will be described in detail below. Figure 1
FIG. 1A is a perspective view of an upper surface side of an electronic circuit module showing a first embodiment of the present invention as seen obliquely from above, and FIG. 1B is an oblique view from above with a bottom surface side of the electronic circuit module as upward. 2 is a sectional view taken along the line 1B-1B in FIG. 1B. The electronic circuit module functions as a switching power supply circuit.

Reference numeral 12 represents a circuit board made of a glass epoxy material or the like, and the surface 12 of the circuit board 12 is shown.
A circuit component 14 that does not require heat radiation and a circuit component 16 that has heat radiation are mounted on A, and a heat radiation plate 20 made of an aluminum plate or the like is fixed to the back surface 12B of the circuit board 12.
The circuit component 14 that does not require heat dissipation is, for example, a chip resistor or a chip capacitor, and the circuit component 16 that requires heat dissipation is, for example, a power transistor for power conversion.

An opening 12C is provided at the approximate center of the circuit board 12.
The circuit component 16 having heat dissipation is fixed to the heat dissipation plate 20 in the opening 12C. Mounting the circuit component 14 on the surface 12A of the circuit board 12 that does not require heat dissipation is
This can be performed by soldering the circuit component 14 to a conductor pattern (not shown) on the circuit board 12 by a reflow method or the like. Further, the circuit component 16 having heat dissipation can be mounted by soldering the leads 16A of the circuit component 16 to the conductor pattern on the circuit board 12.

A plurality of lead terminals 18 used for mounting the electronic circuit module on a mother board (not shown) are provided on the edge of the circuit board 12. The lead terminal 18 is planted in the through hole of the circuit board 12 so that one end thereof projects from the front surface 12A of the circuit board 12 and the other end projects from the back surface 12B of the circuit board 12. The portion of the lead terminal 18 protruding from the back surface 12B of the circuit board 12 is located in a plurality of pores 20A formed in the edge portion of the heat dissipation plate 20 corresponding to the lead terminal 18.

The opening 12C of the circuit board 12 and the pores 20A of the heat dissipation plate 20 are filled with a resin such as epoxy resin or silicon resin. One of the methods for manufacturing the electronic circuit module includes, for example, the following steps.

(A) A step of surface-mounting a circuit component 14 which does not require heat radiation on the surface 12A of the circuit board 12 by a solder reflow method. (B) The circuit component 16 requiring heat radiation is provided on the surface 12A of the circuit substrate 12 by the circuit component 16 being the opening 12 of the circuit substrate 12.
Step to implement so as to face C.

(C) A plurality of lead terminals are formed in a plurality of through holes formed at the edge of the circuit board 12, one end of which protrudes from the surface 12A of the circuit board 12 and the other end of which is the circuit board 12.
Step of planting so as to project from the back surface 12B of the.

After the steps (d), (a) to (c), the heat dissipation plate 20 is placed in the pores 20A of the lead terminal 18.
Is closely attached to the back surface 20B of the circuit board 12 so as to be positioned in the opening 12C of the circuit board 12 and the pores 20A of the heat dissipation plate 20 are filled with a thermosetting resin and cured by heating. Step.

The order of performing the steps (a) to (c) is arbitrary. Further, the three steps of (a) to (c) may be performed at the same time, or the three steps of (a) to (c) may be performed.
Any two steps selected from one step may be performed simultaneously.

When the processes (a) and (c) are carried out simultaneously, this process is performed, for example, on the circuit board 12.
A step of printing and applying paste-like solder to the surfaces of the pads and the through-hole lands formed on the surface 12A of the pad, and a circuit component 14 that does not require heat radiation on the pad.
And pressing the lead terminals 18 into the through holes, and then heating the circuit board to reflow solder the circuit component 14 to the pads and the lead terminals 18 to the through hole lands, respectively. .. When the method of the present invention is carried out in this way, the solder reflow method can be applied when mounting a circuit component or the like on a circuit board, and component mounting is easy.

In the process (d), in order to ensure that the circuit component 16 and the heat sink 20 are kept in close contact with each other, prior to filling the opening 12C of the circuit board 12 with a thermosetting resin, The circuit component 16 may be temporarily fixed to the heat dissipation plate 20 with an ultraviolet curable adhesive or the like.

According to this embodiment, since the circuit component 16 having heat radiation is in direct contact with the heat radiation plate 20, the heat radiation property is good. Further, the circuit board 12 and the heat sink 20 are joined by the resin 22 filled in the opening 12C of the circuit board 12 and the resin 22 filled in the pores 20A of the heat sink 20. Opening 12 in the center
Since C is formed, the generation of thermal stress due to the difference in the coefficient of linear thermal expansion between the circuit board 12 and the heat sink 20 is dispersed and relaxed,
It is possible to provide an electronic circuit module with high heat resistance and reliability.

Further, the lead terminals 18 erected in the through holes of the circuit board 12 are made of resin 2 for the heat sink 20.
Since it is fixed in the pores 20A of the heat dissipation plate 20 by 2,
The connection strength of the lead terminals is significantly increased as compared with the conventional configuration. As a result, it becomes possible to use a heat sink having a large weight, and it becomes possible to provide a high-output switching power supply circuit module.

When a multilayer printed wiring board is used as the circuit board 12, it becomes possible to increase the packaging density of circuit components or increase the degree of freedom in the arrangement of circuit components.

In the present embodiment, since the lead terminal 18 is positioned substantially at the center of the pore 20A of the heat sink 20, even when the heat sink 20 is made of a conductor, the lead terminal 18 and the heat sink 20 are formed. The insulation between them is secured. On the other hand, the circuit component 16 that requires heat dissipation is directly fixed to the heat dissipation plate 20 in order to improve heat dissipation.

When it is required to ensure the insulation between the circuit component 16 and the heat sink 20, the circuit component 16 is replaced by the heat sink 2.
It is preferable to interpose an insulating film between the circuit component 16 and the heat sink 20 when temporarily fixing to 0. in this case,
Since the thickness of the insulating film can be thin, there is little risk of poor heat dissipation. As the insulating film, an insulating resin printed on the heat sink 20 or a polyimide film stuck on the heat sink 20 can be used.

FIG. 3A is a perspective view of the upper surface side of the electronic circuit module showing the second embodiment of the present invention as seen obliquely from above,
3B is a perspective view of the electronic circuit module as seen from obliquely above with the bottom side facing upward, and FIG. 4 is a sectional view taken along line 3B-3B in FIG. 3B.

This embodiment differs from the first embodiment shown in FIGS. 1 and 2 in that the heat dissipation plate 20 is also provided with an opening 20B, and a circuit which does not require heat dissipation on the back surface 12B of the circuit board 12 in this opening 20B. The point is that the component 14 is surface-mounted. The opening 20B of the heat sink 20 is formed so as not to overlap the opening 12C of the circuit board 12 and separate from the pore 20A of the heat sink 20. Further, the resin 22 may be filled in the opening 20B of the heat dissipation plate 20.

According to this structure, in addition to the effect of the first embodiment shown in FIGS. 1 and 2, the circuit component 1 on the circuit board 12 is added.
The effect that the mounting density of No. 4 can be increased is produced. Further, by forming the opening 20B in the heat dissipation plate 20, the heat dissipation plate 20 is divided into a plurality of portions at the cross-sectional position of FIG. 4, and there is an effect that noise in the switching power supply circuit can be reduced. Specifically, it is as follows.

Conventionally, in the case where the heat radiation plate generally made of metal has a flat plate shape, high-frequency noise generated in the power transistor which is a component of the switching power supply circuit is passed through the heat radiation plate to the current / voltage control circuit. There is a problem that it acts as noise and the output current and output voltage become unstable.

In this embodiment, by forming the opening 20B in the heat sink 20, the heat sink is divided into a plurality of parts in the cross-sectional shape of the heat sink, and the high frequency noise generated in the power transistor passes through the heat sink. It becomes difficult to act on the current and voltage control circuits, and the output current and output voltage can be stabilized.

FIG. 5A is a perspective view of an upper surface side of an electronic circuit module showing a third embodiment of the present invention as seen obliquely from above,
FIG. 5 (B) is a perspective view of the electronic circuit module as seen from diagonally above with the bottom side facing upward, and FIG. 5 (C) shows the heat sink of the electronic circuit module in the same direction as in FIG. 5 (B). It is the perspective view seen from.

This embodiment differs from the first embodiment shown in FIGS. 1 and 2 in that the opening 12 of the circuit board 12 in the heat sink 20 is formed.
The point is that the portion corresponding to C is formed thick, and the convex surface 20C of the thick portion of the heat dissipation plate 20 is positioned inside the opening 12C of the circuit board 12. Convex surface 2 of the thick portion of heat sink 20
0C is, for example, located on the same plane as the surface 12A of the circuit board 12 when the electronic circuit module is assembled.

According to this embodiment, when assembling the electronic circuit module, the heat sink 20 is previously attached to the circuit board 12.
The convex surface 20C of the heat dissipation plate to which the circuit component 16 having heat dissipation is to be fixed is fixed to the back surface of the circuit board 1
Since it can be located on the same plane as the second surface 12A, the circuit component 16 that requires heat dissipation can be surface-mounted on the circuit board 12 together with the circuit component 14 that does not require heat dissipation in the same step.

FIG. 6A is a perspective view of an upper surface side of an electronic circuit module showing a fourth embodiment of the present invention as seen obliquely from above,
FIG. 6 (B) is a perspective view of the electronic circuit module as seen from diagonally above with the bottom side facing upward, and FIG. 6 (C) shows the heat sink of the electronic circuit module in the same direction as in FIG. 6 (B). It is the perspective view seen from.

This embodiment differs from the third embodiment in FIG. 5 in that a heat dissipation plate 20 having a narrower width than that in the third embodiment is used, and this heat dissipation plate 20 partially covers the circuit board 12. Thus, the back surface 12B of the circuit board 12 is partially exposed, and the circuit component 14 that does not require further heat dissipation is mounted on this exposed surface.

According to this embodiment, in addition to the effect of the third embodiment of FIG. 5, there is an effect that the mounting density of the circuit components 14 which does not require heat radiation to the circuit board 12 can be increased.

In the embodiment described above, the opening 12C is formed in the approximate center of the circuit board 12, and the circuit component 16 requiring heat radiation is fixed to the heat sink 20 in the opening 12C. The invention is not limited to this configuration. For example, a cutout may be formed from the edge of the circuit board to a substantially central portion, and circuit components that require heat radiation may be fixed to the heat dissipation plate in the cutout.

[0038]

The effects of the present invention will be apparent from the description of the embodiments and the like, and the main ones will be confirmed and clarified as follows. That is, according to the present invention, it is possible to provide an electronic circuit module having good heat dissipation characteristics and high heat resistance.

[Brief description of drawings]

FIG. 1 is a perspective view of an electronic circuit module showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line 1B-1B in the first embodiment of the present invention.

FIG. 3 is a perspective view of an electronic circuit module showing a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line 3B-3B in the second embodiment of the present invention.

FIG. 5 is a perspective view of an electronic circuit module and the like showing a third embodiment of the present invention.

FIG. 6 is a perspective view of an electronic circuit module and the like showing a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of a conventional electronic circuit module.

[Explanation of symbols]

 12 circuit board 14 circuit component that does not require heat dissipation 16 circuit component that requires heat dissipation 18 lead terminal 20 heat sink

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 1/18 S 9154-4E Q 9154-4E

Claims (10)

[Claims] 1. A circuit board (12) having an opening or a notch (12C) formed at a substantially central portion thereof, a heat dissipation plate (20) fixed to a first surface of the circuit board, and the circuit board (12). ) Mounted on the second surface of the circuit board, the main body of which is fixed to the heat dissipation plate (20) in the opening or notch (12C) of the circuit board, which requires heat dissipation, and the circuit board (12). An electronic circuit module comprising a circuit component (14) which is surface-mounted on the second surface of (4) and does not require heat dissipation. 2. A plurality of pores (2
0A) is formed such that one end of the circuit board (12) projects from the first surface of the circuit board into the pores and the other end projects from the second surface of the circuit board. The electronic circuit module according to claim 1, wherein a lead terminal (18) is planted in the inner part. 3. The electronic circuit module according to claim 2, wherein the openings or notches (12C) of the circuit board and the pores (20A) of the heat dissipation plate are filled with a resin (22). 4. An opening (20B) is formed in a portion of the heat dissipation plate (20) corresponding to the opening or notch (12C) of the circuit board and the pore (20A). The circuit board (12) further has a circuit component (14) that is surface-mounted on the first surface of the circuit board (12) and does not require heat dissipation, and the opening of the heat dissipation plate is filled with a resin (22). The electronic circuit module according to claim 3, wherein: 5. The heat dissipation plate (20) is provided so as to partially cover the first surface of the circuit board (12), and the exposed portion of the first surface of the circuit board does not require further heat dissipation. The electronic circuit module according to claim 3, wherein the circuit component (14) is surface-mounted. 6. The electronic circuit module according to claim 1, wherein the circuit component (16) that requires heat dissipation is fixed to the heat dissipation plate (20) through an insulating film. 7. A portion of the heat sink (20) corresponding to the opening or notch (12C) of the circuit board is formed thick, and the convex surface (20C) of the thick portion of the heat sink is the circuit. The electronic circuit module according to claim 1, wherein the electronic circuit module is located in the opening or notch (12C) of the substrate. 8. The electronic circuit module according to claim 1 or 4, wherein the circuit component (16) requiring heat dissipation is a power transistor, and the electronic circuit including the power transistor is a switching power supply circuit. 9. A first step of surface-mounting a circuit component (14) which does not require heat radiation on a first surface of a circuit board (12) having an opening or a notch (12C) formed at a substantially central portion thereof, Circuit parts (16) requiring heat radiation on the first surface of the circuit board (12)
A second step of mounting the component so that the component faces the opening or notch (12C), and the first surface and the second surface of the circuit board at the edge of the circuit board (12).
After the third step of embedding a plurality of lead terminals (18) so as to project from the surface and the first, second and third steps, a plurality of pores (20A) are formed at the edges. The heat radiating plate (20) is brought into close contact with the second surface of the circuit board (12) so that the lead terminals (18) are located in the pores and the circuit component (1
While the 6) is in close contact with the heat sink (20), the resin (22) is filled in the opening or notch (12C) of the circuit board and the pore (20A) of the heat sink to solidify the resin. 4. The method for manufacturing an electronic circuit module, comprising: 10. The surface mounting of the circuit component (14) which does not require heat radiation in the first step, the mounting of the circuit component (16) which requires heat radiation in the second step, and the lead terminal in the third step ( The method of manufacturing an electronic circuit module according to claim 9, wherein the planting of 18) is performed simultaneously by a solder reflow method.