JP2012074539A - Flexible printed wiring board, electronic apparatus, method for manufacturing the flexible printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible printed wiring board which is excellent in heat radiation characteristics and is manufactured without increasing the number of manufacturing processes and the manufacturing cost, and to provide an electronic apparatus including the flexible printed wiring board and a method for manufacturing the flexible printed wiring board.SOLUTION: In a flexible printed wiring board 10 for mounting an exothermic electronic component 20, a heat radiating region R formed by an uneven pattern is provided in a part of a conductive layer 12 provided on both front and rear surfaces of a base substrate 11.

Description

  The present invention relates to a flexible printed wiring board, an electronic device including the flexible printed wiring board, and a method for manufacturing the flexible printed wiring board.

Increasingly, exothermic electronic components are mounted on flexible printed circuit boards (hereinafter referred to as FPC), including lighting.
Such heat-generating electronic components are subject to performance degradation such as degradation of electrical characteristics and degradation of optical characteristics due to the heat generated by the self during driving, and thus demand for FPCs having a heat radiation function has increased. ing.
Conventionally, as an FPC having a heat radiation function, an FPC to which a heat sink or a heat radiation sheet is attached is generally used.
As examples of such FPC, there are Patent Documents 1 and 2 below.

JP 2006-286680 A JP 2010-98128 A

The above Patent Document 1 is an invention related to a wiring board, and has an advantage of providing a grease-less circuit board in which a soldered portion does not peel off in a temperature cycle.
Patent Document 2 is an invention related to a heat dissipation structure, and can efficiently dissipate the heat generated by the exothermic device, and can also prevent dust such as carbon powder that adversely affects the electrical characteristics of the exothermic device. There is an advantage that it is possible to provide a heat dissipation structure without generation and protrusion of metal fiber.
However, since both Patent Documents 1 and 2 are configured to attach heat sinks and heat dissipation sheets, which are separate members, to the FPC, a process for attaching the heat sink and heat dissipation sheet to the FPC in manufacturing an FPC having a heat dissipation function. There is a problem that the cost of parts and the like increases as the number of devices increases.

  Therefore, the present invention eliminates the problems in the prior art and can be manufactured without increasing the manufacturing process and manufacturing cost, and is a flexible printed wiring board excellent in heat dissipation characteristics, an electronic device including the flexible printed wiring board, and It is an object of the present invention to provide a method for manufacturing the flexible printed wiring board.

  The flexible printed wiring board of the present invention is a flexible printed wiring board for mounting an exothermic electronic component, and heat is dissipated by a concavo-convex pattern on a part of a conductive layer provided on one surface or both surfaces of a substrate. The first feature is that an area is provided.

  According to the first aspect of the present invention, the flexible printed wiring board is a flexible printed wiring board for mounting a heat-generating electronic component, and is a conductive layer provided on one or both surfaces of the substrate. Since the heat radiation area by the concave / convex pattern is provided in a part, heat generated by the heat-generating electronic component can be efficiently radiated by the heat radiation area by the concave / convex pattern. Therefore, it can be set as the flexible printed wiring board excellent in the heat dissipation characteristic.

  In addition to the first feature of the present invention, the flexible printed wiring board of the present invention has a second feature that the concavo-convex pattern is formed by forming a convex portion by plating on the conductive layer.

  According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, the concavo-convex pattern is formed by forming convex portions by plating on the conductive layer. The pattern can be easily formed. Therefore, it can be set as the flexible printed wiring board provided with the heat dissipation function which can be manufactured without increasing a manufacturing process and manufacturing cost.

  In addition to the first feature of the present invention, the flexible printed wiring board of the present invention has a third feature that the concave / convex pattern is formed by forming a concave portion by etching in the conductive layer.

  According to the third feature of the present invention, in addition to the function and effect of the first feature of the present invention, the concave / convex pattern is formed by forming a concave portion by etching in the conductive layer. Can be formed easily. Therefore, it can be set as the flexible printed wiring board provided with the heat dissipation function which can be manufactured without increasing a manufacturing process and manufacturing cost.

  The flexible printed wiring board of the present invention has a conductive layer provided on both the front and back surfaces of the base material through through-hole plating in addition to any one of the first to third features of the present invention. The fourth feature is that they are electrically connected.

  According to the fourth feature of the present invention, in addition to the function and effect of any one of the first to third features of the present invention, the conductive layers provided on both the front and back surfaces of the base Since it is electrically connected via hole plating, heat generated by the heat-generating electronic component can be transferred to both the front and back surfaces of the flexible printed wiring board to be dissipated. Therefore, it can be set as the flexible printed wiring board which was further excellent in the heat dissipation characteristic.

  According to a fifth aspect of the present invention, there is provided an electronic apparatus comprising the flexible printed wiring board according to any one of the first to fourth aspects.

  According to the fifth aspect of the present invention, since the electronic device includes the flexible printed wiring board according to any one of the first to fourth characteristics, the manufacturing process and the manufacturing cost are not increased. The electronic device can be manufactured and has excellent heat dissipation characteristics.

  Moreover, the manufacturing method of the flexible printed wiring board of this invention is a manufacturing method of the flexible printed wiring board as described in the said 2nd characteristic, Comprising: The conductive layer provided in both the front and back of the said base material is through-hole plating. In the case of the electrical connection via, the convex portions are formed at the same time during the plating process for electrically connecting the conductive layers provided on the front and back surfaces of the base material via the through-hole plating. This is the sixth feature.

  According to the sixth feature of the present invention, the method for producing a flexible printed wiring board is the method for producing a flexible printed wiring board according to the second feature, and is provided on both surfaces of the base material. In the case where the conductive layer is electrically connected via through-hole plating, the plating step is for electrically connecting the conductive layers provided on both the front and back surfaces of the base material via through-hole plating. Since it forms simultaneously in this case, the flexible printed wiring board excellent in the thermal radiation characteristic can be manufactured, without increasing a manufacturing process and manufacturing cost.

  Moreover, the manufacturing method of the flexible printed wiring board of this invention is a manufacturing method of the flexible printed wiring board as described in said 3rd characteristic, Comprising: The circuit wiring formation for forming the said recessed part and circuit wiring in the said conductive layer The seventh feature is that the step is formed simultaneously with etching.

  According to the seventh feature of the present invention, there is provided a method for producing a flexible printed wiring board according to the third feature, wherein the concave portion is connected to the conductive layer by circuit wiring. In the circuit wiring forming process for forming the circuit board, the flexible printed wiring board having excellent heat dissipation characteristics can be manufactured without increasing the manufacturing process and manufacturing cost.

According to the flexible printed wiring board of the present invention, the electronic device including the flexible printed wiring board, and the manufacturing method of the flexible printed wiring board, the heat radiation characteristics can be manufactured without increasing the manufacturing process and the manufacturing cost. An excellent flexible printed wiring board and an electronic device including the flexible printed wiring board can be obtained.
Moreover, it can be set as the manufacturing method of the flexible printed wiring board excellent in the thermal radiation characteristic which can be manufactured without increasing a manufacturing process and manufacturing cost.

It is a figure which shows the flexible printed wiring board which concerns on the 1st Embodiment of this invention, Comprising: (a) is a top view, (b) is a bottom view, (c) is the cross section in the aa line direction of (a). FIG. It is the figure which showed typically the state which the heat which generate | occur | produced in the electronic component moves in the flexible printed wiring board in the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which simplifies and shows the manufacturing process of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which simplifies and shows the manufacturing process of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the flexible printed wiring board which concerns on the 2nd Embodiment of this invention. It is sectional drawing which simplifies and shows the manufacturing process of the flexible printed wiring board which concerns on the 2nd Embodiment of this invention. It is sectional drawing which simplifies and shows the manufacturing process of the flexible printed wiring board which concerns on the 2nd Embodiment of this invention. It is a figure which shows the flexible printed wiring board concerning the 3rd Embodiment of this invention, Comprising: (a) is a top view, (b) is sectional drawing in the bb line direction of (a). It is sectional drawing which simplifies and shows the manufacturing process of the flexible printed wiring board which concerns on the 3rd Embodiment of this invention.

  Embodiments of a flexible printed wiring board according to the present invention, an electronic device including the flexible printed wiring board, and a method for manufacturing the flexible printed wiring board according to the present invention will be described with reference to the following drawings 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. 1-4, the flexible printed wiring board 10 concerning the 1st Embodiment of this invention, an electronic device provided with the flexible printed wiring board 10, and the manufacturing method of the flexible printed wiring board 10 are demonstrated.

A flexible printed wiring board 10 according to an embodiment of the present invention is a flexible printed wiring board having a function for dissipating heat generated when a heat generating electronic component mounted on a surface is driven. It is disposed inside the electronic device.
More specifically, the flexible printed wiring board 10 is a so-called double-sided flexible printed wiring board in which conductive layers are provided on both front and back surfaces, and electrically connects an electronic component 20 mounted on the front surface side to an external wiring (not shown). It mainly has a function and a function of radiating heat generated when the electronic component 20 is driven.

  As shown in FIG. 1C, the flexible printed wiring board 10 includes a base material 11, a conductive layer 12, a plating layer 13, and a coverlay layer 14.

The base material 11 serves as a base of the flexible printed wiring board 10 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.
In addition, the thickness of the base material 11 can be suitably changed according to a use. More specifically, it may be about 12.5 to 25 μm for general use and about 50 μm for special use.

The conductive layer 12 includes a circuit wiring region (not shown) in which circuit wiring for electrical connection between the electronic component 20 and external wiring is provided, and a heat dissipation region R for radiating heat generated in the electronic component 20. It is a layer provided.
The conductive layer 12 is made of a conductive metal foil, and is laminated on both the front and back surfaces of the substrate 11 as shown in FIG.
Moreover, as shown in FIG.1 (c), the conductive layer 12 provided in the front and back both surfaces of the base material 11 is electrically connected through the through-hole plating P which comprises the plating layer 13 mentioned later.
Although not shown in detail, the conductive layer 12 laminated on the surface side of the substrate 11 is electrically connected to the portion where the electronic component 20 is mounted via the electrode of the electronic component 20 and the solder H. Circuit wiring is formed. This circuit wiring can be formed using a known forming method such as etching of the conductive layer 12.

For example, copper (Cu) can be used as the conductive metal foil. Of course, it is not limited to copper (Cu), and any material can be used as long as it is normally used as a conductive metal foil for forming a conductive layer of a flexible printed wiring board.
Moreover, the thickness of the conductive layer 12 can be appropriately changed according to the application. More specifically, the general use may be about 12 to 18 μm, and the special use may be about 9 μm or about 35 μm.
As shown in FIG. 1, the substrate 11 and the conductive layer 12 are provided with through holes S for forming through hole plating P described later.
The diameter of the through hole S is preferably about 0.1 to 0.3 mm.
The number of through holes S is not limited to that of the present embodiment, and can be changed as appropriate.

The plating layer 13 is a metal coating layer for electrically connecting circuit wirings formed on the conductive layers 12 on both the front and back surfaces of the substrate 11 and for transferring and releasing heat generated when the electronic component 20 is driven. .
In the first embodiment, as shown in FIG. 1C, a part of the plating layer 13 that covers the conductive layer 12 is a through-hole plating P and a convex portion T.
Here, “through-hole plating” means plating that covers the entire surface of the inner hole of the through-hole S and the peripheral regions of the front and back openings of the through-hole S.

The through-hole plating P electrically connects the circuit wiring formed on the conductive layer 12 laminated on both the front and back surfaces of the base material 11 and also stacks heat generated when the electronic component 20 is driven on both the front and back surfaces of the base material 11. This is for transferring heat to the conductive layer 12.
As shown in FIG. 1 (c), this through-hole plating P is formed on the entire surface of the inner hole of the through-hole S and the peripheral area of the front and back openings of the through-hole S by a known method such as electroless plating or electrolytic plating. It can form by carrying out copper plating using the method.

The convex portion T is for radiating heat generated when the electronic component 20 is driven.
In the first embodiment, as shown in FIGS. 1B and 1C, a plurality of convex portions T are formed on a part of the conductive layer 12 laminated on the back surface side of the substrate 11. .
With such a configuration, the convex portion T can be a fin for heat dissipation, and as shown in FIGS. 1B and 1C, the concave portion U and the convex portion are formed on a part of the conductive layer 12. It is possible to provide a heat dissipation region R composed of a concavo-convex pattern formed of T.
Here, the conductive layers 12 laminated on the front and back surfaces of the substrate 11 are electrically connected by the through-hole plating P as described above. Therefore, as shown by the dashed arrows in FIG. 2, the heat generated when the electronic component 20 mounted on the conductive layer 12 on the surface side of the substrate 11 is driven is not limited to the surface side of the flexible printed wiring board 10, Heat can be transferred to the conductive layer 12 on the back side through the through-hole plating P, and heat can be dissipated from the heat dissipation region R by heat exchange (convection / radiation) with air.
In addition, by forming the heat dissipation area R with a concavo-convex pattern, the surface area of the heat dissipation area R can be increased with a simple configuration, and the heat generated when the electronic component 20 is driven can be efficiently dissipated from the heat dissipation area R. .
Further, by forming the convex portion T on the conductive layer 12 laminated on the back surface side of the base material 11 electrically connected through the through-hole plating P, as shown in FIG. A heat radiation region R can be formed immediately below. Therefore, since the heat radiation region R can be formed closer to the mounting location of the electronic component 20, the heat generated when the electronic component 20 is driven can be radiated more efficiently.

Further, the convex portion T is formed simultaneously with the through-hole plating P by copper plating in the plating step for forming the through-hole plating P constituting the plating layer 13.
By setting it as such a structure, in the manufacturing process of the flexible printed wiring board 10, the convex part T for thermal radiation can be formed, without adding another process or another member.

That is, conventionally, as a heat dissipation structure in a flexible printed wiring board on which an electronic component that generates heat during driving is mounted, a structure in which another member such as a heat sink or a heat dissipation sheet is attached to the flexible printed wiring board is generally used.
In such a configuration, in the manufacturing process of the flexible printed wiring board, there is a problem in that the manufacturing process and the manufacturing cost increase because a separate process or a separate member is required to form the heat dissipation structure.

On the other hand, by setting it as the structure of this invention, in the manufacturing process of the flexible printed wiring board 10, without adding another process or another member, it is the convex part T by the recessed part U and plating on some conductive layers 12. It is possible to easily provide the heat radiation region R composed of the uneven pattern to be formed.
Therefore, it can be set as an electronic device provided with the flexible printed wiring board 10 and the flexible printed wiring board 10 which can be manufactured without increasing a manufacturing process and manufacturing cost, and was excellent in the thermal radiation characteristic.
The thickness of the convex portion T is desirably about 8 to 18 μm.
Further, the number, shape, size, formation position, arrangement, and the like of the convex portions T are not limited to those of the present embodiment, and can be changed as appropriate. For example, the convex portions T may be formed regularly or irregularly as individual protrusions one by one. Moreover, it is good also as a structure which forms the convex part T in stripe form. Moreover, when forming the some convex part T, arrangement | positioning of the convex part T is good also as what kind of structures, such as linear form, curvilinear form, annular | circular shape, or what combined these.

The coverlay layer 14 is a layer that forms an insulating layer of the flexible printed wiring board 10. The coverlay layer 14 can be formed by printing a polyimide film on a part of the plating layer 13 using a hot press or an insulating resin ink.
As the insulating resin ink, for example, polyimide ink or epoxy resin ink can be used.
Further, the thickness of the coverlay layer 14 can be appropriately changed according to the application. More specifically, a general use may be about 27.5 to 55 μm, and a special use may be about 22.5 μm or about 65 μm.

The electronic component 20 is a semiconductor element that generates heat when driven.
In the present embodiment, a light emitting diode (hereinafter referred to as an LED) is used as a semiconductor element. Of course, it is not limited to the LED, and can be appropriately changed according to the configuration of an electronic device using the flexible printed wiring board 10 such as an integrated circuit (hereinafter referred to as an IC).
Further, the size and number of the electronic components 20 are not limited to those of the present embodiment.

  Next, a method for manufacturing the flexible printed wiring board 10 and a method for mounting the electronic component 20 on the flexible printed wiring board 10 according to the first embodiment of the present invention will be described with reference to FIGS.

First, as shown to Fig.3 (a), the board | substrate which laminated | stacked the conductive layer 12 which consists of copper foil on both surfaces of the base material 11 is prepared.
Then, a through hole S is formed on the substrate by drilling through a through hole forming step A shown in FIG.
And the plating layer 13 containing the through-hole plating P and the some convex part T is formed using copper plating by the plating process B shown in FIG.3 (c). More specifically, a plating mask is applied to the conductive layer 12 in the portion where the plurality of convex portions T are formed, and the copper plating is performed without applying a plating mask to other portions including the portion where the through-hole plating P is formed. The through-hole plating P and the plurality of convex portions T are formed at the same time by simultaneously performing the above steps and peeling the plating mask.
Then, in the circuit wiring formation process C shown in FIG. 3D, an etching mask laminate is applied to the circuit wiring formation portion, the mask is developed, the etching is performed, and the etching mask is peeled off. Form.
Then, in the cover lay layer forming step D shown in FIG. 4A, the cover lay layer 14 is formed by printing a polyimide film on a part of the plating layer 13 using hot pressing or insulating resin ink. As the insulating resin ink, for example, polyimide ink or epoxy resin ink can be used.
Through the above steps, the flexible printed wiring board 10 according to the first embodiment of the present invention is manufactured.
Then, after the solder H is printed on the mounting position of the electronic component 20 in the plating layer 13 by the electronic component mounting step E shown in FIG. 4B, the electronic component 20 is mounted and subjected to a reflow process. Is mounted on the flexible printed wiring board 10.
In this way, the flexible printed wiring board 10 on which the electronic component 20 is mounted is disposed inside an electronic device such as a cellular phone (not shown).

  Next, with reference to FIGS. 5-7, the flexible printed wiring board 30, the electronic device provided with the flexible printed wiring board 30, and the manufacturing method of the flexible printed wiring board 30 which concern on the 2nd Embodiment of this invention are demonstrated.

First, a flexible printed wiring board 30 according to a second embodiment of the present invention will be described with reference to FIG.
The flexible printed wiring board 30 according to the second embodiment is obtained by modifying the configuration and forming method of the heat radiation area with respect to the flexible printed wiring board 10 according to the first embodiment of the present invention described above. . Since the other configurations are the same as those of the first embodiment of the present invention described above, the same alphabet or the last one digit number and the same alphabet are used for the same member and the same function. The following description is omitted.

Referring to FIG. 5, in flexible printed wiring board 30 according to the second embodiment, a plurality of concave portions U are formed in a part of conductive layer 32 and plating layer 33 laminated on the back surface side of base material 31. In addition, a heat radiating region R having a concave / convex pattern is provided by the concave portion U and the convex portion T formed by the conductive layer 32 and the plating layer 33.
The recess U is formed at the same time as the circuit wiring at the time of etching for forming the circuit wiring on the conductive layer 32 in the circuit wiring forming step.
By adopting such a configuration, without attaching another member such as a heat sink or heat radiating sheet for heat radiation to the flexible printed wiring board 30, it is possible to remove the uneven pattern from the concave / convex pattern only by etching a part of the conductive layer 32 and the plating layer 33. The heat radiation area | region R which becomes can be formed. Further, the recess U and the circuit wiring can be formed simultaneously in the same process.
Therefore, in the manufacturing process of the flexible printed wiring board 30, the heat radiation region R composed of the concave / convex pattern formed by the concave portion U and the convex portion T is easily provided in a part of the conductive layer 32 without adding another step or another member. be able to.
Therefore, it can be set as the electronic device provided with the flexible printed wiring board 30 and the flexible printed wiring board 30 excellent in the thermal radiation characteristic which can be manufactured without further increasing a manufacturing process and manufacturing cost.
Further, by etching the conductive layer 32 and the plating layer 33 to form the recess U, the surface area of the heat radiation region R can be further increased, and the heat generated when the electronic component 20 is driven can be radiated more efficiently. Can be made.
Note that the number, shape, size, formation position, and the like of the recesses U are not limited to those of the second embodiment, and can be changed as appropriate.

Next, a method for manufacturing the flexible printed wiring board 30 and a method for mounting the electronic component 20 on the flexible printed wiring board 30 according to the second embodiment of the present invention will be described with reference to FIGS.
The same steps, the same members, and the same functions as the method for manufacturing the flexible printed wiring board 10 and the method for mounting the electronic component 20 on the flexible printed wiring board 10 according to the first embodiment of the present invention described above are the same. The same thing shall be attached to the alphabet or the last digit number and the alphabet.

First, as shown in FIG. 6A, a substrate is prepared in which conductive layers 32 made of copper foil are laminated on both surfaces of a base material 31.
Then, a through hole S is formed on the substrate by drilling through a through hole forming step A shown in FIG.
And the plating layer 33 containing the through-hole plating P is formed using copper plating by the plating process B shown in FIG.6 (c).
Then, in the circuit wiring forming process C shown in FIG. 6D, an etching mask laminate is applied to the circuit wiring forming portion and the recessed portion U forming portion, mask development is performed, etching is performed, and the etching mask is peeled off. A circuit wiring (not shown) and a plurality of recesses U are formed simultaneously.
Then, in the cover lay layer forming step D shown in FIG. 7A, the cover lay layer 34 is formed by printing a polyimide film on a part of the plating layer 33 using a hot press or an insulating resin ink. As the insulating resin ink, for example, polyimide ink or epoxy resin ink can be used.
Through the above steps, the flexible printed wiring board 30 according to the second embodiment of the present invention is manufactured.
Then, after the solder H is printed on the mounting position of the electronic component 20 in the plating layer 33 by the electronic component mounting step E shown in FIG. 7B, the electronic component 20 is mounted and subjected to a reflow process. Is mounted on the flexible printed wiring board 30.
In this way, the flexible printed wiring board 30 on which the electronic component 20 is mounted is disposed inside an electronic device such as a mobile phone (not shown).

  Next, with reference to FIGS. 8 and 9, a flexible printed wiring board 40 according to a third embodiment of the present invention, an electronic device including the flexible printed wiring board 40, and a method for manufacturing the flexible printed wiring board 40 will be described.

First, a flexible printed wiring board 40 according to a third embodiment of the present invention will be described with reference to FIG.
The flexible printed wiring board 40 according to the third embodiment is different from the above-described flexible printed wiring board 10 according to the first embodiment of the present invention in the configuration and formation method of the flexible printed wiring board and the heat radiation area. It is a deformed one. Since the other configurations are the same as those of the first embodiment of the present invention described above, the same alphabet or the last one digit number and the same alphabet are used for the same member and the same function. The following description is omitted.

Referring to FIG. 8, in the flexible printed wiring board 40 according to the third embodiment, the flexible printed wiring board is a so-called single-sided flexible printed wiring board in which a conductive layer is provided only on one side. Further, a plurality of concave portions U are formed in a part of the conductive layer 42 laminated on the surface side of the base material 41, and the heat dissipation region R formed by the concave and convex patterns by the concave portions U and the convex portions T formed by the conductive layer 42. Is provided.
The concave portion U is formed at the same time as the circuit wiring during the etching for forming the circuit wiring on the conductive layer 42 in the circuit wiring forming step.
By adopting such a configuration, it is possible to easily form the heat radiation region R composed of the uneven pattern only by etching the conductive layer 42 without attaching another member such as a heat sink or heat radiation sheet for heat radiation to the flexible printed wiring board 40. Can be formed. Further, the recess U and the circuit wiring can be formed simultaneously in the same process.
Therefore, it can be set as an electronic device provided with the flexible printed wiring board 40 and the flexible printed wiring board 40 excellent in the thermal radiation characteristic which can be manufactured without further increasing a manufacturing process and manufacturing cost.
Moreover, by using the flexible printed wiring board 40 as a so-called single-sided flexible printed wiring board, the flexible printed wiring board 40 can be a thin flexible printed wiring board having excellent heat dissipation characteristics.
The number, shape, size, formation position, and the like of the recesses U are not necessarily limited to those of the third embodiment, and can be changed as appropriate.

Next, with reference to FIG. 9, the manufacturing method of the flexible printed wiring board 40 concerning the 3rd Embodiment of this invention and the mounting method to the flexible printed wiring board 40 of the electronic component 20 are demonstrated.
The same steps, the same members, and the same functions as the method for manufacturing the flexible printed wiring board 10 and the method for mounting the electronic component 20 on the flexible printed wiring board 10 according to the first embodiment of the present invention described above are the same. The same thing shall be attached to the alphabet or the last digit number and the alphabet.

First, as shown in FIG. 9A, a substrate is prepared in which a conductive layer 42 made of copper foil is laminated on one side of a base material 41.
Then, in the circuit wiring forming step C shown in FIG. 9B, an etching mask laminate is applied to the circuit wiring forming portion and the recessed portion U forming portion, mask development is performed, etching is performed, and the etching mask is peeled off. Circuit wiring (not shown) and a plurality of recesses U are formed simultaneously.
Then, in the cover lay layer forming step D shown in FIG. 9C, a polyimide film is printed on a part of the conductive layer 42 using a hot press or an insulating resin ink to form the cover lay layer 44. As the insulating resin ink, for example, polyimide ink or epoxy resin ink can be used.
Through the above steps, the flexible printed wiring board 30 according to the third embodiment of the present invention is manufactured.
Then, after the solder H is printed on the mounting position of the electronic component 20 in the conductive layer 42 by the electronic component mounting step E shown in FIG. 9D, the electronic component 20 is mounted and reflow-processed. Is mounted on the flexible printed wiring board 40.
In this way, the flexible printed wiring board 40 on which the electronic component 20 is mounted is disposed inside an electronic device such as a cellular phone (not shown).

In the first and second embodiments of the present invention described above, the heat dissipation region R is provided only on the back side of the flexible printed wiring boards 10 and 30, but the invention is not necessarily limited to such a configuration. It is good also as a structure provided in both the surface side of the flexible printed wiring boards 10 and 30, and a back surface side.
By setting it as such a structure, it can be set as the flexible printed wiring boards 10 and 30 which were further excellent in the thermal radiation characteristic.
In the first and second embodiments of the present invention described above, a space is left in the through hole S. However, the present invention is not limited to such a configuration. It is good also as a structure filled with an electrically conductive paste.
By setting it as such a structure, it can be set as the flexible printed wiring boards 10 and 30 which were further excellent in the thermal radiation characteristic.

  According to the present invention, in a flexible printed wiring board on which a heat generating electronic component (such as an LED or an IC) is mounted, the flexible printed wiring having excellent heat dissipation characteristics that can be manufactured without increasing the manufacturing process and manufacturing cost. Board, an electronic device including the flexible printed wiring board, and a method for manufacturing the flexible printed wiring board, a flexible printed wiring board on which a heat-generating electronic component is mounted, and an electronic device including the flexible printed wiring board. Industrial applicability in the field is high.

DESCRIPTION OF SYMBOLS 10 Flexible printed wiring board 11 Base material 12 Conductive layer 13 Plating layer 14 Coverlay layer 20 Electronic component 30 Flexible printed wiring board 31 Base material 32 Conductive layer 33 Plating layer 34 Coverlay layer 40 Flexible printed wiring board 41 Base material 42 Conductive layer 43 plating layer 44 cover lay layer A through hole forming process B plating process C circuit wiring forming process D cover lay layer forming process E electronic component mounting process H solder P through hole plating R heat dissipation area S through hole T convex part U concave part

Claims (7)

  A flexible printed wiring board for mounting exothermic electronic components, characterized in that a heat dissipation area by a concave and convex pattern is provided on a part of a conductive layer provided on one or both surfaces of a base material. Flexible printed wiring board.   The flexible printed wiring board according to claim 1, wherein the concavo-convex pattern is formed by forming a convex portion by plating on the conductive layer.   The flexible printed wiring board according to claim 1, wherein the concave / convex pattern is formed by forming a concave portion by etching in the conductive layer.   The flexible printed wiring board according to any one of claims 1 to 3, wherein the conductive layers provided on both the front and back surfaces of the base material are electrically connected through through-hole plating.   An electronic apparatus comprising the flexible printed wiring board according to claim 1.   The method for producing a flexible printed wiring board according to claim 2, wherein the conductive layers provided on both the front and back surfaces of the base material are electrically connected via through-hole plating. A method for producing a flexible printed wiring board, comprising simultaneously forming conductive layers provided on both front and back surfaces of the base material in a plating step for electrically connecting through through-hole plating.   4. The method of manufacturing a flexible printed wiring board according to claim 3, wherein the recess is formed simultaneously with etching in a circuit wiring forming step for forming a circuit wiring on the conductive layer. Manufacturing method of flexible printed wiring board.

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