JP2012023166A - Flexible printed wiring board and heater element radiation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible printed wiring board and a heater element radiation structure provided with the flexible printed wiring board which can improve radiation characteristics with a simple structure.SOLUTION: The flexible printed wiring board 300 in combination with a heater element 100 comprises a circuit region C for electrically connecting the heater element 100 with an external wiring 500 and a radiation-dedicated extended region R disposed on a region outward beyond a region from at least the heater element 100 to the circuit region C for performing only radiation. A heater element radiation structure 1 includes the flexible printed wiring board 300, the heater element 100, a housing 400, and a base part 200 serving as a base of the flexible printed wiring board and grounded to the housing 400. The base part 200 has contact with only a part of the flexible printed wiring board 300 thereby creating a space between the flexible printed wiring board 300 and the housing 400.

Description

  The present invention relates to a flexible printed wiring board and a heat dissipation structure for a heating element including the flexible printed wiring board.

A semiconductor element that generates heat during operation (hereinafter referred to as a heating element) generates heat when driven. Although the heat varies depending on the type of the heat generating element, the performance of the heat generating element tends to decrease as the temperature rises. In recent years, a method for reducing the amount of heat generated by improving the performance of the heat generating element itself has been developed. However, many methods have been developed as a heat dissipation method for removing heat generation in parallel.
Heat dissipation spreads by heat conduction, which is the movement of heat within a solid, and heat transfer, which is the movement of heat from a solid to a fluid (liquid or gas), but the heating element is relatively small and its surface area is also small. For this reason, it is difficult to sufficiently dissipate heat by heat transfer. In most cases, heat radiation is started by heat conduction to a mounting substrate having a large surface area.
For example, a semiconductor laser or the like is often mounted on an aluminum nitride substrate having high thermal conductivity and mounted on a metal package or the like. In addition, CPU is connected to silicon with high thermal conductivity by ball grid array method and then mounted on circuit board such as glass epoxy board. A method of mounting fins is used. In recent thin mobile PCs, a method of inducing heat to a housing at another location with a heat pipe can be seen.
For example, Patent Documents 1 to 3 listed below show such a heat dissipation structure of a heat generating element.

Utility Model Registration No. 3130026 Japanese Patent Laid-Open No. 7-336209 JP-A-11-68360

The above-mentioned Patent Document 1 is an invention related to a radiator of a semiconductor element, and has an advantage that it can be manufactured at a low cost with a simple configuration with a small number of parts.
Patent Document 2 is an invention related to a heat dissipation structure of a semiconductor element, and heat from the semiconductor element can be directly dissipated to the chassis via a heat dissipation surface, a heat dissipation spacer, etc., and a merit that heat dissipation efficiency is improved over conventional heat dissipation methods. There is.
Patent Document 3 is an invention relating to a cooling structure of a semiconductor element, and has an advantage that the semiconductor element can be cooled by efficiently dissipating heat generated from each semiconductor element by a simple means.
However, in the above-mentioned Patent Documents 1 and 2, since the heat dissipating fins 20 and the heat dissipating spacers 8 are provided, it is difficult to provide the heat dissipating fins 20 and the heat dissipating spacers 8 in electronic devices that are becoming smaller. was there.
In Patent Document 3, the printed circuit board 1 and the semiconductor element 3 are electrically connected by the solder balls 6 and a heat conduction path is formed from the upper surface of the semiconductor element 3 to the heat radiating plate 4 via the leaf spring 5. It is the structure to do. In such a configuration using solder balls, since a heat radiation path from the lower side of the semiconductor element is limited, a path for releasing heat from the upper side of the semiconductor element to a housing or the like is generally formed. In the above-mentioned Patent Document 3, the heat conducted through the leaf spring 5 is transmitted to the vicinity of the semiconductor element 3, and thus escapes from the lower side of the semiconductor element 3 through the solder ball 6. There was a problem that the housing temperature increased with heat, and the heat dissipation effect decreased.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a flexible printed wiring board capable of solving the above-described problems in the prior art and improving heat dissipation characteristics with a simple configuration, and a heat dissipation structure for a heating element including the flexible printed wiring board. To do.

  The flexible printed wiring board of the present invention is a flexible printed wiring board combined with a heating element, and is attached to a housing, and is provided with a circuit region for electrical connection between the heating element and external wiring. At the same time, the first feature is that an expansion region dedicated to heat dissipation is provided at least in a region outside the region from the heating element to the circuit region.

  According to the first feature of the present invention, a flexible printed wiring board combined with a heating element, which is attached to a housing, has a circuit area for electrical connection between the heating element and external wiring. In addition to the function of performing electrical connection, the heating element is provided at least in the area outside the area from the heating element to the circuit area. It is possible to provide a flexible printed wiring board having a function of effectively dissipating the heat generated in. Therefore, when attached to a housing, it is possible to provide a flexible printed wiring board that can improve heat dissipation characteristics with a simple configuration.

  In addition to the first feature of the present invention, the flexible printed wiring board of the present invention is provided with a large surface area region formed by bending the tip portion at least at the tip portion of the heat dissipation expansion region. This is the second feature.

  According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, a wide surface area region formed by bending the distal end portion is provided at least at the distal end portion of the heat dissipation expansion region. Since it is provided, the surface area of the expansion region dedicated for heat dissipation can be increased. Therefore, the heat radiation area of the heat radiation-dedicated extended region can be increased, and the heat generated by the heating element can be radiated more effectively.

  In addition to the second feature of the present invention, the flexible printed wiring board of the present invention has a third feature that the large surface area is bent in a bellows shape.

  According to the third feature of the present invention, in addition to the function and effect of the second feature of the present invention, the large surface area is bent in a bellows shape, so that the heat radiation expansion can be performed with a simple configuration. The surface area of the region can be increased.

  In addition to the second feature of the present invention, the flexible printed wiring board of the present invention has a fourth feature that the large surface area is bent in a spiral shape.

  According to the fourth aspect of the present invention, in addition to the function and effect of the second aspect of the present invention, the large surface area is bent in a spiral shape. The surface area of the region can be increased.

  Moreover, the flexible printed wiring board of this invention is a housing | casing contact surface which contacts the said housing | casing in a part of said expansion area only for heat dissipation in addition to any one of the said 1st-4th characteristics of this invention. The fifth feature is that an area is provided.

  According to the fifth aspect of the present invention, in addition to the function and effect of any one of the first to fourth aspects of the present invention, a part of the heat dissipation-extended expansion region is provided with the housing and the contact surface. Since the housing contact surface area is provided, the flexible printed wiring board can be used as a heat transfer path for transferring heat generated by the heat generating element to the housing. Therefore, heat generated by the heating element can be preferentially transferred to a cooler portion. Therefore, the heat generated by the heating element can be radiated more effectively.

  A heat dissipation structure for a heating element according to the present invention includes a flexible printed wiring board according to any one of claims 1 to 5, a heating element, a casing made of a conductive metal, and a base of the flexible printed wiring board. A heat-dissipating structure of a heating element comprising a base part that is grounded to the housing as a base, and the base part is in contact with only a part of the flexible printed wiring board; A sixth feature is that a space is formed between the flexible printed wiring board and the housing.

  According to the sixth aspect of the present invention, the heat dissipating structure of the heat generating element includes the flexible printed wiring board according to any one of claims 1 to 5, a heat generating element, and a casing made of a conductive metal. A heat-dissipating structure of a heat generating element comprising a base portion that becomes a base of the flexible printed wiring board and is grounded to the housing, wherein the base portion is a part of the flexible printed wiring board. Since it is configured so that a space is created between the flexible printed wiring board and the housing, the heat dissipation area can be increased with a simple configuration, and the heat dissipation characteristics are improved. Can be made. Therefore, it is possible to effectively dissipate the heat generated in the heating element. Further, even when there is no surplus space in the vicinity of the heating element, the heat generated in the heating element can be radiated after the flexible printed wiring board is routed to the surplus space. In addition, the flexible printed wiring board can be used as a heat transfer path for transferring heat generated by the heating element to the housing. Therefore, heat generated by the heating element can be preferentially transferred to a cooler portion. Therefore, the heat generated by the heating element can be radiated more effectively.

  According to the flexible printed wiring board of the present invention, heat dissipation characteristics can be improved with a simple configuration. Moreover, according to the heat dissipation structure of the heat generating element of the present invention, the heat dissipation characteristics can be improved with a simple configuration.

It is a perspective view which shows the principal part of the thermal radiation structure of the heat generating element which concerns on the 1st Embodiment of this invention. 2A and 2B are cross-sectional views of the heat dissipation structure of the heat generating element according to the first embodiment of the present invention, in which FIG. 1A is a cross-sectional view in the direction of the aa line in FIG. It is. It is sectional drawing which shows the heat dissipation structure of the conventional heat generating element simplified, (a) is sectional drawing which shows the prior art example provided with the structure which radiates the heat | fever generated by the heat generating element from a housing | casing, (b) is generated with a heat generating element. It is sectional drawing which shows the prior art example provided with the structure which dissipates the heat which did the heat from a radiation fin and a housing | casing. It is sectional drawing which shows the modification 1 of the thermal radiation structure of the heat generating element which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the modification 2 of the thermal radiation structure of the heat generating element which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the modification 3 of the thermal radiation structure of the heat generating element which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the thermal radiation structure of the heat generating element which concerns on the 2nd Embodiment of this invention.

  With reference to the following drawings, an embodiment of a heat dissipating structure of a heat generating element according to the present invention will be described for understanding of the present invention. However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

First, with reference to FIGS. 1-3, the thermal radiation structure of the heat generating element which concerns on the 1st Embodiment of this invention is demonstrated.
A heat-dissipating structure 1 for a heating element according to the first embodiment of the present invention is disposed in an electronic device such as a mobile phone, a projector, and a television. As shown in FIG. The base portion 200, the flexible printed wiring board 300, the housing 400, and the external wiring 500 are configured.

The heating element 100 is a semiconductor element that generates heat during operation.
For example, a laser diode can be used as the semiconductor element. Of course, it is not limited to a laser diode, and any semiconductor element that generates heat during operation, such as a light emitting diode, may be used.
The heating element 100 is provided with an electrode (not shown) that is electrically connected to the base part 200 and is placed on the upper surface of the base part 200 via solder.

As shown in FIGS. 1 and 2, the base portion 200 serves as a base for the heat generating element 100 and the flexible printed wiring board 300 and is grounded to the housing 400, and the flexible printed wiring board 300 is connected to the heat generating element 100. It is the ceramic substrate which comprises the electric circuit for connecting.
As a material for forming the ceramic substrate, for example, aluminum nitride can be used. Of course, the material is not limited to aluminum nitride, and any material can be used as long as it is normally used as a material for forming the ceramic substrate.
In addition, an electric circuit (not shown) that is electrically connected to the electrode of the heat generating element 100 and the bonding wire W is formed on the base part 200.

The flexible printed wiring board 300 is a so-called single-sided flexible printed wiring board in which an electric circuit is provided only on one side, and the heating element 100 and the external wiring 500 are connected by connecting the heating element 100 via the base part 200. And the heat generated when the heating element 100 is driven is dissipated.
As shown in FIG. 2B, the flexible printed wiring board 300 includes a base material layer 310, a circuit layer 320, a heat radiation layer 330, and a coverlay layer 340.
As shown in FIG. 1, in the present embodiment, the flexible printed wiring board 300 has a substantially U-shaped outer shape in plan view and avoids the heat generating element 100, and solder H on the upper surface of the base portion 200. By being mounted via (see FIG. 2), it is combined with the heating element 100 and attached to the housing 400.

The base material layer 310 serves as a base of the flexible printed wiring board 300 and is formed of an insulating resin film.
As a resin film, what consists of a resin material excellent in the softness | flexibility is used. For example, any resin film may be used as long as it is normally used as a resin film for forming a flexible printed wiring board such as a polyimide film or a polyester film.
In particular, those having high heat resistance in addition to flexibility are desirable. For example, polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene naphthalate can be preferably used.
The heat-resistant resin may be any resin as long as it is normally used as a heat-resistant resin for forming a flexible printed wiring board, such as a polyimide resin or an epoxy resin.
The base material layer 310 preferably has a thickness of about 5 to 100 μm.

The circuit layer 320 is a layer on which an electric circuit for electrical connection between the heating element 100 and the external wiring 500 is formed via the base part 200. As shown in FIG. It is formed by laminating a conductive metal foil on the lower surface side of the layer 310.
The circuit layer 320 is formed using a known forming method such as etching a conductive metal foil laminated on the base material layer 310.
Further, in the present embodiment, as shown in FIGS. 1 and 2, an area where the circuit layer 320 is formed in the flexible printed wiring board 300 is defined as a circuit area C.
As the conductive metal foil, for example, copper can be used. Of course, the material is not limited to copper, and any material may be used as long as it is normally used as a conductive metal foil for forming the electric circuit of the flexible printed wiring board 300.
The thickness of the circuit layer 320 is desirably about 15 to 110 μm.
As shown in FIG. 2B, the electric circuit formed in the circuit layer 320 is electrically connected to the electric circuit formed in the base part 200 by solder H through the through hole 350.

The heat dissipation layer 330 is a layer for dissipating heat generated when the heat generating element 100 is driven, and a conductive metal foil is laminated on the upper surface side of the base material layer 310 as shown in FIG. Formed with.
In this embodiment, as shown in part in FIG. 2B, an electric circuit is configured by laminating a conductive metal foil on the entire upper surface of the base material layer 310 in the flexible printed wiring board 300. A heat dissipation layer 330 that does not occur is provided over the entire length of the flexible printed wiring board 300.
By adopting such a configuration, as shown in FIGS. 1 and 2, heat dissipation that performs only heat dissipation without forming an electric circuit in a region outside the region from the heating element 100 to the circuit region C in particular. A dedicated extended region R can be formed.
Here, the “region outside the region from the heating element 100 to the circuit region C” means the shorter direction and the longer direction of the flexible printed wiring board 300 than the region surrounding the heating element 100 to the circuit region C. It shall mean the area | region which becomes an outer side toward it.

Further, as shown in FIGS. 1 and 2A, the base 200 that is grounded to the casing 400 is brought into contact with only a part of the flexible printed wiring board 300, and the flexible printed wiring board 300 and the casing 400 are contacted. The space is created between the two.
More specifically, as shown in FIGS. 1 and 2, the size of the base portion 200 is set to a size that allows only the central portion of the flexible printed wiring board 300 to be placed. Only the central portion is placed through the solder H so as to be in contact with the upper surface of the base portion 200 with as large an area as possible while avoiding the heating element 100.
With such a configuration, the heat generated in the heating element 100 can be dissipated by heat transfer from the flexible printed wiring board 300 to the air in the housing 400 via the base part 200, and The surface area of the flexible printed wiring board 300 in contact with the air in the housing 400 can be increased, and the amount of heat radiation can be increased.
At the same time, the heat generated in the heating element 100 can be quickly conducted to the base portion 200 and can be radiated from the housing 400.
Therefore, the flexible printed wiring board 300 and the heat dissipation structure 1 can improve the heat dissipation characteristics with a simple configuration.

That is, as shown by the white arrow in FIG. 2A, in addition to radiating the heat generated in the heating element 100 and transferred to the base portion 200 from the casing 400 made of a conductive metal described later. Heat can be transferred over the entire length of the flexible printed wiring board 300 via the base portion 200, and heat can be dissipated from the upper and lower surfaces of the flexible printed wiring board 300 into the air in the housing 400 by heat transfer.
In addition, by forming the heat dissipation-only extended region R that performs only heat dissipation without configuring an electric circuit, the heat generated in the heating element 100 can be dissipated effectively using the space in the housing 400. .
Therefore, the flexible printed wiring board 300 can effectively dissipate the heat generated in the heating element 100 and the function of performing electrical connection between the heating element 100 and the external wiring 500 via the base part 200, and the base part 200. It can be set as the flexible printed wiring board provided with the function to cool down simultaneously.
In addition, by disposing the heat dissipation layer 330 made of a conductive metal foil on the entire upper surface of the base material layer 310 in the flexible printed wiring board 300, the heat dissipation layer 330 including the heat dissipation dedicated extended region R can be formed with a simple configuration. Can be formed.

As the conductive metal foil, for example, copper can be used. Of course, it is not limited to copper, and any conductive metal foil having a high thermal conductivity may be used.
The thickness of the heat dissipation layer 330 is preferably about 10 to 300 μm.

  That is, as shown in FIG. 3A, the heat dissipation structure of the conventional heat generating element has a configuration in which heat generated in the heat generating element 100 is transferred to the casing 400 through the base portion 200 to be dissipated. As shown in FIG. 3B, the heat dissipation structure 2 of the element and the heat generated by the heat generating element 100 are dissipated by the heat dissipating fins 600 and transferred to the housing 400 via the solder balls 700 to dissipate the heat. A heat-dissipating structure 3 for a heat-generating element provided with is generally used.

However, the heat dissipating structure 2 of the heat generating element has a problem that the heat dissipating amount is insufficient only by the heat dissipating from the casing 400.
Further, in the heat dissipation structure 3 of the heat generating element, although the heat dissipation area can be increased by providing the heat dissipation fins 600, in recent electronic devices that are becoming smaller, there is no space for providing the heat dissipation fins 600 and it is difficult to install. In addition, since the heat radiation path from the lower side of the heating element 100 is limited to the size of the solder ball 700, there is a problem that the heat radiation amount is still insufficient.
As shown in FIG. 3A, a conventional flexible printed wiring board 300 connected to the heating element 100 by wire bonding is placed on a housing 400 and a base portion 200 on which the heating element 100 is placed. Are generally electrically connected by a bonding wire W. Since such a flexible printed wiring board 300 is generally mainly responsible for the function of electrical connection between the heat generating element 100 and the external wiring 500, a region constituting the electric circuit (the circuit in the present embodiment). Other than the region C), those not provided with a region made of a conductive metal foil were common.
That is, a flexible printed wiring board provided with a heat radiation function as a main function by providing a heat radiation-extended expansion region made of a conductive metal foil that performs only heat radiation without constituting an electric circuit at all has been uncommon.
In addition, in the conventional heat-dissipating element heat dissipating structures 2 and 3, the same members and the same functions as those of the heat-dissipating heat dissipating structure 1 of the present embodiment are designated by the same reference numerals, and the following detailed description is omitted. And

  On the other hand, the configuration of the present embodiment, for example, as shown in FIG. 2A, is provided with a heat dissipation-only extended region R that performs only heat dissipation without particularly configuring an electric circuit, thereby reducing the size. Also in recent electronic devices, the heat dissipation area for effectively radiating the heat generated in the heat generating element 100 can be easily increased, and the heat generating element 100 can be used effectively by utilizing the space in the housing 400. The generated heat can be dissipated. That is, the flexible printed wiring board 300 and the heat dissipation structure 1 can improve the heat dissipation characteristics with a simple configuration.

The coverlay layer 340 is a layer that forms an insulating layer of the flexible printed wiring board 300.
As the coverlay layer 340, a polyimide film, a photosensitive resist, a liquid resist, or the like can be used.
The thickness of the coverlay layer 340 is preferably about 20 to 150 μm.
The coverlay layer 340 is attached to the base material layer 310, the circuit layer 320, and the heat dissipation layer 330 via an adhesive such as a thermosetting adhesive (not shown).

The casing 400 constitutes the outer shape of an electronic device such as a mobile phone and accommodates various electronic components such as a heating element.
The housing 400 is made of a conductive metal having high thermal conductivity.
As the conductive metal, for example, copper, silver or the like can be used.
Further, the configuration, shape, size, and the like of the housing 400 are not limited to those of the present embodiment, and can be changed as appropriate.
For example, the housing 400 can include an upper lid. However, in this case, convection occurs between the air inside and outside the housing 400 so that the heat radiated from the flexible printed wiring board 300 to the air inside the housing 400 can be released to the outside of the housing 400. It is desirable to provide such a structure at the same time. By setting it as such a structure, it can be set as the heat dissipation structure 1 with sufficient heat dissipation efficiency also in a housing | casing provided with an upper cover.

The external wiring 500 is two conductive wires that constitute a drive circuit of the heating element 100.
The external wiring 500 is electrically connected to the circuit layer 320 through a through hole 350 provided in the flexible printed wiring board 300 as shown in a simplified manner in FIG. Of course, the electrical connection between the external wiring 500 and the circuit layer 320 is not limited to this, and any configuration may be used as long as the external wiring 500 and the circuit layer 320 can be electrically connected.

In the first embodiment of the present invention, the conductive metal foil is laminated on the entire upper surface of the base material layer 310, so that an electric circuit is not configured as a layer different from the circuit layer 320. Although the heat radiation layer 330 is configured to be provided over the entire length of the flexible printed wiring board 300, it is not necessarily limited to such a configuration.
For example, by providing a conductive metal foil that does not constitute an electric circuit in a region other than the circuit region C in the same layer as the circuit layer 320, the circuit layer 320 and the heat dissipation layer 330 are provided in the same layer. can do. By setting it as such a structure, the flexible printed wiring board 300 can be made thin.

Further, in the first embodiment of the present invention, the central portion of the flexible printed wiring board 300 is placed on the base portion 200 with the heating element 100 avoided, but such a configuration is not necessarily required. The mounting position on the base part 200 in the flexible printed wiring board 300 can be appropriately changed.
For example, the flexible printed wiring board 300 may be configured such that any one end in the longitudinal direction is placed on the base 200.
The shape and size of the flexible printed wiring board 300 are not limited to the configuration of the present embodiment, and can be changed as appropriate. However, at least the contact surface portion with the base portion 200 has a shape and size that allows the heat generating element 100 to be in contact with the base portion 200 in the widest possible area in consideration of heat dissipation. It is desirable to do.
Further, the mounting position of the base unit 200 on the housing 400 is not limited to that of the present embodiment, and can be changed as appropriate.
In this embodiment, the flexible printed wiring board 300 is a so-called single-sided flexible printed wiring board. However, the present invention is not necessarily limited to such a configuration, and at least from the region from the heating element 100 to the circuit region C. In the outer region, the flexible printed wiring board 300 is provided with electric circuits on both sides if it is configured to provide only a heat dissipation extended region R that performs heat dissipation without configuring an electric circuit. It is good also as a structure used as what is called a double-sided flexible printed wiring board.

Next, with reference to FIG. 2, the formation method of the thermal radiation structure 1 of a heat generating element is demonstrated.
First, the heating element 100 is placed on the base part 200 via the solder H. At this time, the electrode of the heating element 100 and the electric circuit of the base part 200 are electrically connected by the bonding wire W.
Then, the base part 200 on which the heating element 100 is placed is attached to the housing 400.
And the flexible printed wiring board 300 is mounted in the base part 200 via solder.
At this time, the electrical circuit of the base unit 200 and the electrical circuit of the flexible printed wiring board 300 are electrically connected via solder.
Then, the external wiring 500 is electrically connected to the electric circuit of the flexible printed wiring board 300.
Through the above steps, the heat dissipating structure 1 for the heat generating element is formed.
Of course, the method of forming the heat dissipation structure 1 of the heat generating element is not limited to such a configuration, and can be changed as appropriate.

  Next, a modification of the first embodiment of the present invention will be described with reference to FIGS.

First, with reference to FIG. 4, the modification 1 of the 1st Embodiment of this invention is demonstrated.
In the first modification, the configuration of the heat dissipation-only extended region R in the first embodiment of the present invention is changed.
Since other configurations are the same as those of the first embodiment of the present invention described above, the same members and the same functions are denoted by the same reference numerals, and the following detailed description is omitted. And

As shown in FIG. 4, in the first modification, a large surface area region R <b> 1 formed by bending the distal end portion is provided at least at the distal end portion of the heat dissipation dedicated expansion region R.
More specifically, on the right side of the heating element 100 in the drawing, the large heat-dissipating extended region R is bent in a bellows shape to provide a large surface area region R1. Further, on the left side of the drawing from the heating element 100, the flexible printed wiring board 300 has a substantially U-shape in plan view, so that the distal end portion of the heat-extended extended region R divided into two forks is bent into a bellows shape. By doing so, the large surface area R1 is provided.
Here, the “large surface area region” refers to a region having a surface area of at least a projected plane area ratio of 1.2 times or more.

By setting it as such a structure, the surface area of the expansion area | region R only for heat radiation can be increased compared with the case where the expansion area | region R only for heat radiation is provided in linear form. Therefore, the heat dissipation area of the heat dissipation dedicated expansion region R can be increased, and the heat generated in the heat generating element 100 can be dissipated more effectively.
Moreover, since the flexible printed wiring board 300 has flexibility, the front-end | tip part of the expansion area | region R only for thermal radiation can be bent easily in a bellows shape. Therefore, it is possible to increase the surface area of the heat dissipation dedicated expansion region R with a simple configuration.

Next, with reference to FIG. 5, the modification 2 of the 1st Embodiment of this invention is demonstrated.
In the second modification, the configuration of the heat dissipation-only extended region R in the first embodiment of the present invention described above is changed.
Since other configurations are the same as those of the first embodiment of the present invention described above, the same members and the same functions are denoted by the same reference numerals, and the following detailed description is omitted. And

As shown in FIG. 5, in the second modification, a large surface area region R1 formed by bending the distal end portion is provided at least at the distal end portion of the heat dissipation dedicated expansion region R.
More specifically, on the right side of the heating element 100 in the drawing, the large heat-dissipating extended region R is bent in a spiral shape to provide a large surface area region R1. Further, on the left side of the drawing from the heating element 100, the flexible printed wiring board 300 has a substantially U-shape in plan view, so that the distal end portion of the heat-extended extended region R divided into two forks is bent into a bellows shape. By doing so, the large surface area R1 is provided.

By setting it as such a structure, the surface area of the expansion area | region R only for heat radiation can be increased compared with the case where the expansion area | region R only for heat radiation is provided in linear form. Therefore, the heat dissipation area of the heat dissipation dedicated expansion region R can be increased, and the heat generated in the heat generating element 100 can be dissipated more effectively.
Moreover, since the flexible printed wiring board 300 has flexibility, the front-end | tip part of the expansion area | region R only for thermal radiation can be bent easily in a bellows shape and a spiral shape. Therefore, it is possible to increase the surface area of the heat dissipation dedicated expansion region R with a simple configuration.

Next, with reference to FIG. 6, the modification 3 of the 1st Embodiment of this invention is demonstrated.
In the third modification, the configurations of the heat-extended extended region R and the casing 400 in the first embodiment of the present invention described above are changed.
Since other configurations are the same as those of the first embodiment of the present invention described above, the same members and the same functions are denoted by the same reference numerals, and the following detailed description is omitted. And

As shown in FIG. 6, in the third modification, at least the distal end portion of the heat dissipation dedicated expansion region R is provided with a large surface area region R1 formed by bending the tip portion, and In this part, a housing contact surface region R2 that is in contact with the housing 400 is provided.
More specifically, on the right side of the heating element 100 in the drawing, the large heat-dissipating extended region R is bent in a bellows shape to provide a large surface area region R1.
Further, on the left side of the drawing from the heating element 100, the flexible printed wiring board 300 has a substantially U-shape in plan view, so that the distal end portion of the heat-extended extended region R divided into two forks is bent into a bellows shape. As a result, a large surface area R1 is provided, and a part of the heat radiation extended area R from the heat generating element 100 to the large surface area R1 is a casing contact surface area R2, and the casing is connected via grease (not shown). 400 is in contact with the upper lid 410.
The casing 400 is configured to include an upper lid 410.
As shown in FIG. 6, the housing 400 has a housing 400 in which the heat dissipated from the flexible printed wiring board 300 into the air in the housing 400 can be released to the outside of the housing 400. A gap S is formed so that convection occurs between the inside and outside air. Of course, the structure that causes convection between the air inside and outside the housing 400 is not limited to such a configuration, and can be changed as appropriate.

By providing the large surface area R1 in this way, the surface area of the heat dissipation dedicated expansion region R can be increased as compared with the case where the heat dissipation dedicated expansion region R is provided in a straight line. Therefore, the heat dissipation area of the heat dissipation dedicated expansion region R can be increased, and the heat generated in the heat generating element 100 can be dissipated more effectively.
Further, the housing contact surface region R <b> 2 is provided, and the flexible printed wiring board 300 is also used as a heat transfer path for transferring the heat generated in the heating element 100 to the housing 400 by contacting the housing 400 with the surface. be able to.
Therefore, since the base part 200 is not grounded, the contribution to heat dissipation is low, and heat generated in the heating element 100 is preferentially transferred to the upper lid 410 in a relatively cold state to dissipate. Can do.
Therefore, the upper lid 410 can also be added as a heat radiation area, and the heat generated in the heat generating element 100 can be radiated more effectively.
In addition, since the flexible printed wiring board 300 has flexibility, the distal end portion of the heat dissipation dedicated expansion region R can be easily bent into an accordion shape and guided to the upper lid 410. Therefore, the surface area of the heat dissipation dedicated expansion region R can be increased with a simple configuration, and the upper lid 410 can be used as a heat dissipation area.

In the first to third modifications of the first embodiment of the present invention, the shape of the large surface area region R1 is a bellows shape or / and a spiral shape, but is not necessarily limited to such a configuration. As long as the surface area of the heat dissipation dedicated expansion region R can be increased by bending the tip of the heat dissipation dedicated expansion region R, the shape can be changed as appropriate. Further, the number of bendings is not limited to those of the first to third modifications, and can be changed as appropriate.
In addition, if the wide surface area R1 formed by bending the heat dissipation expansion area R is provided at least at the tip of the heat dissipation expansion area R, the position where the wide surface area R1 is formed is also the first to third modifications. The configuration is not limited to the above, and can be changed as appropriate.
In the first to third modifications, the large surface area R1 and / or the housing contact surface area R2 are provided on both the right and left sides of the heating element 100. However, the present invention is not limited to such a configuration. Alternatively, the large surface area region R1 and / or the housing contact surface region R2 may be provided on either the right side or the left side of the heating element 100.
The formation position of the housing contact surface region R2 on the flexible printed wiring board 300 is not limited to that in the third modification of the first embodiment of the present invention, and can be changed as appropriate. More preferably, in consideration of heat dissipation, it is desirable to form at a position where it can be in contact with the upper lid 410 in a region other than the vicinity of the heating element 100.
Here, the “region in the vicinity of the heating element 100” means a region where the linear distance from the heating element 100 to the upper lid is in the range of 1 to 100 mm.

Next, a heat dissipation structure for a heat generating element according to a second embodiment of the present invention will be described with reference to FIG.
The heat-dissipating structure 4 for the heat generating element according to the second embodiment of the present invention is different from the heat-dissipating structure 1 for the heat generating element according to the first embodiment of the present invention. The shape is changed.
Since other configurations are the same as those of the first embodiment of the present invention described above, the same members and the same functions are denoted by the same reference numerals, and the following detailed description is omitted. And

As shown in FIG. 7, in the heat-dissipating structure 4 for a heat generating element according to the second embodiment of the present invention, the heat generating element 100 is placed on the upper surface of the flexible printed wiring board 300, and the flexible printed wiring board 300 is mounted. In addition, it is placed on the upper surface of the base part 200 that is grounded to the casing 400. Further, the heating element 100 and the electric circuit (not shown) of the flexible printed wiring board 300 are electrically connected by a bonding wire W, whereby the heating element 100 is mounted on the flexible printed wiring board 300 and connected by wire bonding. Further, although not shown in detail in FIG. 7, the shape of the flexible printed wiring board 300 is not a substantially U shape in a plan view but is a flat plate shape.
By setting it as such a structure, the heat which generate | occur | produced in the heat generating element 100 can be directly transferred to the flexible printed wiring board 300, and can be radiated. Therefore, the heat dissipation characteristics can be improved with a simple configuration.
Accordingly, the flexible printed wiring board 300 has a function of electrically connecting the heating element 100 and the external wiring 500 and a function of effectively radiating heat generated in the heating element 100 and cooling the heating element 100 at the same time. It can be a printed wiring board.

Note that, in the second embodiment of the present invention, as in the first embodiment of the present invention described above, the heat dissipation-only extended region R may be formed in the same layer as the circuit layer 320.
Further, as in the first embodiment of the present invention described above, the placement position of the flexible printed wiring board 300 on the base portion 200 can be changed as appropriate.
Further, as in the first embodiment of the present invention described above, the flexible printed wiring board 300 may be a so-called double-sided flexible printed wiring board.
Further, as in the first embodiment of the present invention described above, the size of the flexible printed wiring board 300 can be appropriately changed.
In addition, as in the first embodiment of the present invention described above, the mounting position of the base unit 200 on the housing 400 can be changed as appropriate.
Further, as in the first embodiment of the present invention described above, the configuration, shape, size, and the like of the housing 400 can be changed as appropriate.
Moreover, it is good also as a structure which provides the large surface area area | region R or / and housing | casing contact surface area | region R2 similar to the modifications 1-3 of the 1st Embodiment of the present invention mentioned above.

  The present invention has industrial applicability in the field of flexible printed wiring boards combined with heating elements. Moreover, the industrial applicability in the field of the heat dissipation structure of the heat generating element provided with the flexible printed wiring board is high.

1, 4 Heat-dissipating structure of heat-generating element 100 Heat-generating element 200 Base unit 300 Flexible printed wiring board 310 Base material layer 320 Circuit layer 330 Heat-dissipating layer 340 Coverlay layer 350 Through-hole 400 Housing 410 Upper lid 500 External wiring 600 Heat-dissipating fin 700 Solder Ball C Circuit area H Solder R Extended area exclusively for heat dissipation R1 Large surface area R2 Housing contact area S Clearance W Bonding wire

Claims (6)

  A flexible printed wiring board to be combined with a heating element, which is attached to a housing, has a circuit region for electrical connection between the heating element and an external wiring, and at least the heating element to the circuit A flexible printed wiring board characterized in that an expansion region dedicated to heat radiation is provided in a region outside the region up to the region, which only performs heat radiation.   The flexible printed wiring board according to claim 1, wherein a wide surface area region formed by bending the distal end portion is provided at least at the distal end portion of the heat dissipation dedicated expansion region.   The flexible printed wiring board according to claim 2, wherein the large surface area region is bent in a bellows shape.   The flexible printed wiring board according to claim 2, wherein the large surface area region is bent in a spiral shape.   The flexible printed wiring board according to any one of claims 1 to 4, wherein a housing contact surface area that contacts the housing is provided in a part of the heat dissipation-dedicated extended region.   The flexible printed wiring board according to any one of claims 1 to 5, a heating element, a casing made of a conductive metal, and a base of the flexible printed wiring board that is grounded to the casing. A heat-dissipating structure of a heat generating element comprising a base part, wherein the base part is in contact with only a part of the flexible printed wiring board, so that the flexible printed wiring board and the housing A heat dissipating structure for a heating element, characterized in that a space is formed between them.

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