JP3536824B2 - Heat dissipation structure of substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiating structure for electronic components, particularly, a substrate housed in a digital camera.

[0002]

2. Description of the Related Art Conventionally, various techniques have been disclosed for a heat radiation structure of a substrate for releasing heat generated from a substrate on which an IC or the like is mounted to the outside. For example, JP-A-8-6473
Japanese Patent Application Publication No. 1 (1999) -1995 discloses a heat conductive member formed by enclosing a leaf spring having a spread in the surface direction so as to generate a force on a contact surface together with a heat conductive grease in a flexible film, and a heat generating member. A heat dissipation structure that dissipates heat by interposing between heat dissipation members is disclosed.

In addition, Japanese Patent Application Laid-Open Nos. 8-139235 and
A similar heat dissipation structure is also disclosed in Japanese Patent Application Publication No. 1-26968. In each of these, a heat conduction member is disposed between a substrate and a heat dissipation member which are heating members, so that the heat of the heating member is transmitted to the heat dissipation member. A heat transfer structure is disclosed.

Further, Japanese Patent Application Laid-Open No. H11-177264 discloses a heat dissipation structure in which a heating member and a storage case are connected by a heat transfer portion having good adhesion.

[0005]

However, when these heat radiation structures are used in a small electronic device, a heat radiation member such as a heat sink or a cooling fin needs to be present, which causes a space problem. In particular, since digital cameras and the like tend to be small, the space for arranging the substrates is small. In particular, there is a large space problem associated with heat radiation of heat radiation members such as ICs for controlling CCDs. On the other hand, the circuit tends to have a higher clock due to the increase in the number of pixels of the CCD, which is an image sensor, and the amount of heat generated by the IC that controls the CCD is increasing year by year. Furthermore, the substrate is mounted with high density, and the escape route of heat is decreasing.

To solve this problem, the amount of heat generated can be reduced by suppressing the current consumption of the circuit. However, the extent to which the current consumption of the circuit can be reduced is limited, and the current situation is that it is no longer possible to catch up with the space problem associated with miniaturization of devices and substrates.

Further, with the increase in the clock frequency of the circuit, interference noise between the substrates is a problem that cannot be ignored. In particular, the problem of the interference noise between adjacent substrates mounted with high density is large.

Accordingly, a first technical problem to be solved by the present invention is to provide a heat dissipation structure for a substrate which can effectively dissipate heat even when the space for disposing the substrate is small.

A second technical problem to be solved by the present invention is to provide a heat dissipation structure for a substrate which can solve the problem of interference noise between adjacent substrates.

[0010]

Means for Solving the Problems and Action / Effect The present invention provides a heat dissipation structure for a substrate having the following structure in order to solve the above technical problems.

The heat dissipation structure of this substrate is such that a heat-generating substrate on which heat-generating electronic components are mounted, and a non-heat-generating substrate having a smaller amount of heat generation than the heat-generating substrate are arranged substantially in parallel to face each other. A heat conductive member is provided between the two substrates to be in close contact with both substrate surfaces, and the heat generated in the heat generating substrate is radiated to the non-heat generating substrate.

In the above structure, the heat dissipation structure of the substrate is effectively used in high-density mounting in which a plurality of substrates are arranged so as to be substantially parallel and adjacent to each other. Then, by devising the configuration of the electronic components mounted on the arranged substrates, the substrates are classified into heat-generating substrates and non-heat-generating substrates. The heat-generating substrate is a substrate on which at least electronic components generating a large amount of heat, such as an integrated circuit for controlling a solid-state imaging device, are mounted, and the entire substrate generates a large amount of heat, and is likely to be heated to a high temperature during use. On the other hand, a non-heat-generating substrate is a substrate whose heat generation is smaller than that of a heat-generating substrate, such as mounting an electronic circuit that generates a small amount of heat, so that the substrate does not become hotter than the heat-generating substrate during use. is there. These two types of substrates are arranged substantially in parallel so that their surfaces face each other. When there are two or more non-heat-generating substrates, the order of arrangement does not matter in particular. For example, a non-heat-generating substrate may be arranged so as to sandwich the heat-generating substrate, Two sheets may be arranged.

[0013] A heat conducting member is provided between the substrates arranged adjacent to each other. As a result, the heat-generating substrate and the non-heat-generating substrate are thermally coupled, and the heat generated by the heat-generating substrate radiates from the surface of the heat-generating substrate in contact with the heat conducting member to the non-heat-generating substrate. Note that each substrate may be connected to an exterior cover or the like, for example, to radiate heat to the outside.

Therefore, according to the above configuration, the heat capacity of the entire substrate is increased, and the temperature accompanying the heat generation of the entire substrate can be lowered. In addition, the heat generated by the heat-generating substrate is released to the non-heat-generating substrate without using a special space and a heat-radiating member by utilizing the heat-radiating property of the substrate. As a result, it is not necessary to secure an extra space for heat dissipation with respect to heat generation due to downsizing of the electronic device and increase in clock frequency.

The heat dissipation structure of the substrate according to the present invention can be configured in various modes as described below.

Preferably, the non-heat-generating substrate is disposed adjacent to an exterior cover that houses the substrate, and is so attached to a surface of the non-heat-generating substrate adjacent to the exterior cover and an inner wall of the exterior cover. A heat conducting member is provided to radiate heat to the exterior cover.

In the above configuration, the non-heat-generating substrate directly or indirectly thermally coupled to the heat-generating substrate via another non-heat-generating substrate is attached to an outer cover of an electronic device containing these substrates. Arrange them so that they are adjacent. Then, heat can be efficiently released to the outer cover by the heat conductive member provided so as to be in close contact with the inner wall of the outer cover and the surface of the non-heat-generating substrate.

According to the above configuration, heat is thermally coupled to the outer cover over a wide area, so that heat can be efficiently released to the outside. Further, since the heat generated by the heat-generating substrate is radiated through the non-heat-generating substrate, the temperature of the outer cover can be prevented from becoming high.

Preferably, the heat conducting member is constituted by a grounded shield layer and a heat transfer layer.

In the above structure, the shield layer is made of a conductive material, and for example, a metal sheet, a metal mesh, a conductive resin, or the like can be suitably used. Further, as the conductive resin, a resin obtained by mixing a conductive material such as a carbon powder or a metal powder into the above-described heat conductive member can be used. According to the above configuration, by supporting the shield layer serving as the electrostatic shield with the heat transfer layer, the heat conductive member can also perform the function of the electrostatic shield. Since the heat conducting member is widely provided on the surface of the substrate, it is effective as a support for an electrostatic shield that needs to cover the substrate surface widely. Further, heat radiation and shielding between substrates can be performed simultaneously without using a member for attaching the electrostatic shield.

In the above structure, preferably, the heat conductive member has a structure in which the shield layer is provided between two heat transfer layers, and the shield layer is grounded via the heat generating substrate.

In the above structure, the heat conductive member has a three-layer structure in which a heat transfer layer is provided so as to sandwich the shield layer. Contact with the circuit on the surface can be prevented. The shield layer is grounded via a ground pattern provided on the heat-generating substrate. The grounding position at this time is preferably provided near the end of the heat-generating substrate so as to cover the electronic components mounted on the heat-generating substrate and remove external interference noise. According to the above configuration, the heat-generating substrate can be shielded from interference noise from another adjacent substrate.

In the above structure, preferably, the heat-generating substrate has a needle-like portion connected to a grounding land on a surface facing the heat-conducting member. A part penetrates through the heat transfer layer and connects to the shield layer.

In the above configuration, when the heat conductive member and the heat-generating substrate are brought into close contact with each other, the conductive needle-shaped portion connected to the grounding land provided on the surface of the heat-generating substrate is opposed to the heat conductive member. The shield layer is grounded by penetrating through the heat transfer layer and contacting the shield layer of the heat conductive member.

According to the above configuration, the shield layer can be easily grounded to the heat-generating substrate, and the shield layer can be prevented from coming into contact with a portion other than the grounding lands of the heat-generating substrate.

In each of the above structures, preferably, the heat conducting member is a gel polymer.

According to the above configuration, the heat conducting member can be easily deformed, the electronic component can be mounted on the surface, the unevenness on the surface of the substrate can be covered, and the substrate can be firmly adhered.
In addition, the adhesiveness to the substrate surface is good and it is difficult to peel off. Therefore, the coupling between the substrates can be made closer.

In the above configuration, preferably, the gel polymer is a sheet having an adhesive surface.

[0029] Preferably, the gel polymer includes a ceramic powder.

In the above configuration, for example, a ceramic polymer can be mixed with a gel polymer to form a sheet and used. According to the above configuration, since the ceramic powder which is a solid powder having good heat conductivity is included, the heat conductivity of the gel polymer constituting the heat conduction member is improved. Therefore, the thermal coupling between the substrates can be increased.

The above-described heat dissipation structure of the substrate can be suitably used for a digital camera.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital camera according to each embodiment using a substrate heat radiation structure of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a main part showing an arrangement of a substrate of the digital camera according to the first embodiment. The heat-generating substrate 10 is a multilayer substrate on which a heat-generating component 12 and a non-heat-generating electronic component 13 that generates less heat than the heat-generating component 12 are mounted. The non-heat-generating substrate 30 has an electronic component 32 that generates a small amount of heat, and has a solid GND pattern 31 in an inner layer. On the non-heat-generating substrate 30, electronic components are mounted so that the temperature does not become higher than that of the heat-generating substrate 10 when the digital camera is used. Note that components that are easily affected by heat (for example, a distance measuring sensor) are not mounted on the heat-generating substrate 10 and the non-heat-generating substrate 30 but are mounted on another substrate that is not thermally coupled to the heat-generating substrate 10. Is preferred.

The two substrates are arranged adjacent to each other such that their surfaces face each other. At this time, both substrates are arranged so that the heat-generating component 12 faces the non-heat-generating substrate 30. With this arrangement, the heat-generating component 12 is in direct contact with the heat-conducting member 20, so that the heat generated by the heat-generating component 12 can be radiated more efficiently.

A gel-like heat conducting member 20 is arranged between the substrates 10 and 30 so as to be in contact with both surfaces. The heat conducting member 20 is a resin of a fluid having a high viscosity, which itself has a heat radiation property and can conduct heat. In addition, since the heat conducting member 20 is in a gel state, it can be deformed so as to be in contact with the unevenness of the surfaces of both substrates due to the electronic components (12, 32) provided on both substrates, so that the surfaces of both substrates are firmly attached. And close contact. As the heat conductive member, for example, a commercially available gel-like heat conductive adhesive sheet or the like is suitably used.

With such a substrate arrangement structure, the heat generated in the heat-generating substrate 10 is transmitted through the heat conducting member 20 to the non-heat-generating substrate 30 having a small calorific value.
Therefore, when viewed from both substrates as a whole, the heat capacity with respect to the amount of generated heat increases, and the temperature rise of the heat-generating substrate 10 can be prevented. Further, by using a gel-like resin as the heat-conducting member 20 mixed with a solid powder having good heat-conductivity such as ceramic powder, the thermal coupling can be further enhanced.

FIG. 2 is a cross-sectional view of a main part showing an arrangement of a substrate of a digital camera according to a second embodiment. As in the first embodiment described above, the arrangement of the board in this embodiment is similar to that of the first embodiment, except that the heat-generating substrate 10a on which the heat-generating component 12a and the non-heat-generating component 13a are mounted and the solid pattern 31a on the inner layer on which the non-heat-generating component 32a is mounted. The exothermic substrates 30a are arranged substantially in parallel so as to face each other, and a gel-like heat conducting member 20a is provided between the two substrates. The heat generated from the heat-generating substrate 10a is
The heat is dissipated to the non-heat-generating substrate 30a via the first substrate 0a, so that the temperature of both substrates can be prevented from rising.

The non-heat-generating substrate 30a is
Fixed to. Metal frame 23 and non-heating substrate 30a
Is provided with a surface pattern for grounding. A mounting hole for fixing is provided, and a solid pattern provided on the inner surface of the mounting hole is connected to the solid pattern 31a of the inner layer and the front pattern. The metal frame 23 is connected to the exterior body 24, and the non-heat-generating substrate 30a is
2, the heat is transmitted from the non-heat-producing substrate 30a to the exterior body 24 through the metal frame 23 and is radiated to the outside.

FIG. 3 is a cross-sectional view of a main part showing an arrangement of a substrate of a digital camera according to a third embodiment. As in the first embodiment described above, the arrangement of the board in this embodiment is similar to that of the first embodiment except that the heat-generating substrate 10b on which the heat-generating component 12b and the non-heat-generating component 13b are mounted and the solid pattern 31b on the inner layer on which the non-heat-generating component 32b is mounted are provided. The heat-generating substrates 30b are arranged substantially in parallel so as to face each other, and a gel-like heat conducting member 20b is provided between the two substrates. The heat generated from the heat-generating substrate 10b is
The heat is dissipated to the non-heat-generating substrate 30b via Ob, so that the temperature of both substrates can be prevented from rising.

The non-heat-generating substrate 30b is provided substantially parallel to an arbitrary wall of the exterior body 25 in which the substrate is stored. The heat conducting member 21 is provided between the non-heat-generating substrate 30b and the exterior body so as to be in close contact with the surface of the substrate and the inner wall of the exterior body, and the heat of the non-heat-generating substrate 30b can be radiated to the exterior body 25. . That is, the heat generated by the heat-generating substrate 10b is radiated from the exterior body 25 to the outside via the non-heat-generating substrate 30b. With this configuration, a special member for radiating the heat of the substrate to the outside is not required. In addition, the exothermic substrate 1
Since Ob is not directly thermally coupled to the exterior body, it is possible to prevent the exterior body 25 from becoming too hot.

FIG. 4 is a cross-sectional view of a main part showing a process of arranging the substrates of the digital camera according to the fourth embodiment. FIG. 5 is a cross-sectional view of a principal part showing an arrangement configuration of a substrate of the digital camera in FIG. In the present embodiment, the substrate is a heating component 12.
heat-generating substrate 10c mounted with the heat-generating component 13c and the non-heat-generating component 13c
And a non-heat-generating substrate 30c on which an electronic component 32c that generates a small amount of heat is mounted and a solid pattern 31c of GND is provided in an inner layer. A grounding land 11c is provided on the surface of the heat-generating substrate 10c, and is connected to the ground of the digital camera body. The heat conducting member 20c is disposed between the two substrates and is brought into close contact with the surfaces of the substrates as shown by arrows 50 and 51.

The heat conducting member 20c has a three-layer structure in which the heat transfer layer sandwiches the shield layer 26c. The heat transfer layer is made of a heat conductive gel polymer adhesive sheet, and the shield layer 26c is made of a gel conductive polymer material. In a high-definition digital camera, the processing clock of the substrate becomes faster. For example, when the heating component 12c is a microcomputer or the like that controls a CCD, this is 100 MHz.
It operates with a clock close to z. For this reason, ICs and ICs
Is mixed with noise related to the high-speed clock. In order to prevent noise emitted from the component 12c and the substrate, it is preferable to provide an electrostatic shield that covers the component 12c and shields between the substrates such as a shield substrate.

FIG. 6 is a view for explaining a manufacturing process of the heat conducting member. As shown in FIG. 6A, a gel conductive polymer serving as the shield layer 26c is applied to the surface of the adhesive sheet 28a. Then, point the other adhesive sheet to arrow 5
As shown by reference numerals 2 and 53, they are laminated on the shield layer 26c. The adhesive sheet 28b is provided with small holes 29, as shown in FIG. The small hole 29 is provided at a position corresponding to the ground land 11c when the heat conductive member 20c is overlaid on the heat-generating substrate 10c.

As shown in FIG. 6B, the adhesive sheet 28
When the shield layer 26c is sandwiched between the a and 28b, the gel-like shield layer 26c protrudes from the small holes 29 provided in the adhesive sheet 28b. As shown in FIG. 5, the heat conductive member 20c manufactured in this manner is connected to both substrates 10c and 3c.
0c, the grounding land 11 of the heat-generating substrate 10c
c, and the shield layer 26c can be grounded. Therefore, the heat conduction member 2 for heat dissipation
Since 0c is a support member for the shield layer serving as the electrostatic shield, it is not necessary to separately provide a member for providing the electrostatic shield. Therefore, it is not necessary to provide a space for this, and it is possible to solve the problem of space in a case where the digital camera is also a small digital camera.

FIG. 7 is a cross-sectional view of a principal part showing a step of arranging the substrates of the digital camera according to the fourth embodiment. FIG. 8 is a cross-sectional view of a principal part showing an arrangement configuration of a substrate of the digital camera in FIG. In the present embodiment, the substrate is a heating component 12.
heat-generating substrate 10d on which a non-heat-generating component 13d is mounted
And a non-heat-generating substrate 30d on which an electronic component 32d having a small heat generation is mounted and a solid pattern 31d of GND is provided in an inner layer. A grounding land 11d is provided on the surface of the heat-generating substrate 10d, and is connected to the ground of the digital camera body. A needle-like portion 15d extending substantially perpendicular to the substrate surface is arranged from the grounding land 11d. A heat conducting member 20d is arranged between both substrates,
Adhere to the surface of the substrate.

The heat conductive member 20d has a three-layer structure in which the heat transfer layer sandwiches the shield layer 26d. The heat transfer layer is made of a heat conductive gel polymer adhesive sheet, and the shield layer 26c is made of a metal mesh. The heat conductive member 20d is manufactured by adhering two pressure-sensitive adhesive sheets to each other so as to sandwich the metal mesh therebetween.

As shown by arrows 54 and 55 in FIG. 7, the heat-generating substrate 10d and the non-heat-generating substrate 30d
The substrate is arranged so as to be sandwiched by d. At this time, since the heat conductive member 20d is made of a gel-like adhesive tape, as shown in FIG. 8, the needle-like portion 15d provided on the heat-generating substrate 10d breaks through the heat transfer layer and the shield layer 26d.
Connect to ground. Therefore, the shield layer can be easily grounded.

As described above, according to the present invention, there is no need to provide a space for providing a heat radiating member and the like.
The generated heat can be dissipated. Further, the shield between the substrates can be performed without using a member for attaching the electrostatic shield.

It should be noted that the present invention is not limited to the above embodiment, but can be implemented in various other modes. For example, in each of the above embodiments, the number of the heat-generating substrate and the number of the non-heat-generating substrate are one, but a plurality of these may be used.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an arrangement configuration of a substrate of a digital camera according to a first embodiment.

FIG. 2 is an essential part cross-sectional view showing an arrangement configuration of a substrate of a digital camera according to a second embodiment.

FIG. 3 is an essential part cross-sectional view showing an arrangement configuration of a substrate of a digital camera according to a third embodiment.

FIG. 4 is an essential part cross-sectional view showing a step of arranging substrates of a digital camera according to a fourth embodiment.

FIG. 5 is a cross-sectional view of a main part showing an arrangement configuration of a board of the digital camera in FIG. 4;

FIG. 6 is an explanatory diagram of a manufacturing process for a heat conducting member of the substrate of the digital camera in FIG. 4;

FIG. 7 is an essential part cross-sectional view showing a step of arranging substrates of a digital camera according to a fourth embodiment.

8 is a cross-sectional view of a main part showing an arrangement configuration of a board of the digital camera in FIG. 7;

[Explanation of symbols]

10,10a-10d Heat-generating substrate 11c, 11d Land for grounding 12,12a-12d Heating parts 13, 13a-13d Non-heating parts 15d needle part 20, 20a to 20d, 21 Heat conductive member 22 screws 23 Metal frame 24, 25 exterior body 26c, 26d shield layer 28a, 28b adhesive tape 29 small hole 30, 30a-30d Non-heat-generating substrate 31, 31a-31d Solid pattern 32, 32a-32d Non-heating parts

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 7/20

Claims (9)

(57) [Claims] 1. A heat-generating substrate on which heat-generating electronic components are mounted, and a non-heat-generating substrate having a smaller heat generation than the heat-generating substrate are arranged substantially in parallel to face each other, and the two adjacent substrates are arranged. A heat dissipation member for a substrate, wherein a heat conducting member is provided so as to be in close contact with both substrate surfaces, and heat generated in the heat-generating substrate is radiated to the non-heat-generating substrate. 2. The non-heat-generating substrate is disposed adjacent to an exterior cover that houses the substrate, and is heated so as to be in close contact with the surface of the non-heat-generating substrate adjacent to the exterior cover and the inner wall of the exterior cover. The heat dissipating structure for a substrate according to claim 1, wherein a conductive member is provided to dissipate heat to the exterior cover. 3. The heat dissipation structure for a substrate according to claim 1, wherein the heat conduction member is constituted by a shield layer and a heat transfer layer which are grounded. 4. The heat conduction member has a structure in which the shield layer is provided between two heat transfer layers, and the shield layer is grounded via the heat-generating substrate. The heat dissipation structure for a substrate according to claim 3. 5. The heat-generating substrate has a needle-like portion connected to a grounding land on a surface facing the heat-conducting member,
The heat dissipation structure for a substrate according to claim 4, wherein the needle-like portion penetrates the heat transfer layer and is connected to the shield layer when the heat transfer member is in close contact with the heat conduction member. 6. The heat dissipation structure for a substrate according to claim 1, wherein the heat conducting member is a gel polymer. 7. The heat dissipation structure for a substrate according to claim 6, wherein the gel polymer is a sheet having an adhesive surface. 8. The heat dissipation structure for a substrate according to claim 6, wherein the gel polymer includes a ceramic powder. 9. A digital camera using the heat dissipation structure of a substrate according to claim 1.