WO2017098910A1 - Heat dissipating circuit board - Google Patents

Heat dissipating circuit board Download PDF

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Publication number
WO2017098910A1
WO2017098910A1 PCT/JP2016/084469 JP2016084469W WO2017098910A1 WO 2017098910 A1 WO2017098910 A1 WO 2017098910A1 JP 2016084469 W JP2016084469 W JP 2016084469W WO 2017098910 A1 WO2017098910 A1 WO 2017098910A1
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WO
WIPO (PCT)
Prior art keywords
heat
circuit board
heat conductive
heat dissipation
laminated
Prior art date
Application number
PCT/JP2016/084469
Other languages
French (fr)
Japanese (ja)
Inventor
齊藤　裕久
元木　健作
淑文 内田
Original Assignee
住友電気工業株式会社
住友電工プリントサーキット株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 住友電気工業株式会社, 住友電工プリントサーキット株式会社 filed Critical 住友電気工業株式会社
Priority to JP2017555004A priority Critical patent/JP6691137B2/en
Priority to CN201680071741.6A priority patent/CN108370643B/en
Publication of WO2017098910A1 publication Critical patent/WO2017098910A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details

Definitions

  • the present invention relates to a heat dissipation circuit board.
  • This application claims priority based on Japanese Patent Application No. 2015-240564 filed on Dec. 09, 2015, and incorporates all the description content described in the above Japanese application.
  • Some electronic components mounted on a printed wiring board have a large amount of heat generated during operation, such as a light emitting diode (LED).
  • LED light emitting diode
  • a heat dissipating metal plate or the like is generally laminated in order to prevent deterioration of the function of the electronic component or circuit damage due to heating.
  • a heat dissipating circuit board includes a printed wiring board having an insulating sheet and a conductive pattern laminated on a front surface side of the insulating sheet, and heat conductive adhesion to the back surface side of the insulating sheet of the printed wiring board.
  • a heat-dissipating circuit board comprising a thermally conductive base material laminated via an agent layer, including at least a part of the projected region of the thermally conductive base material, and having a thickness of the insulating sheet more than other regions Has a small heat dissipation area.
  • FIG. 1 is a schematic cross-sectional view showing a heat dissipating circuit board according to a first embodiment of the present invention.
  • FIG. 2 is a schematic plan view of the heat dissipation circuit board of FIG.
  • FIG. 5 is a schematic cross-sectional view showing a heat dissipating circuit board according to an embodiment different from FIG.
  • the insulating film when the insulating film is thinned in order to improve the thermal conductivity, when the circuit board is curved and arranged on the inner surface of the housing having a step, the insulating film is formed at the curved portion. Insulation properties may be reduced.
  • the present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a heat dissipating circuit board that can effectively promote heat dissipation of electronic components and has high insulation reliability.
  • the heat dissipating circuit board according to one embodiment of the present invention can provide a circuit board that can effectively promote heat dissipation of electronic components and has high insulation reliability.
  • a heat dissipating circuit board includes a printed wiring board having an insulating sheet and a conductive pattern laminated on a front surface side of the insulating sheet, and heat conductive adhesion to the back surface side of the insulating sheet of the printed wiring board.
  • a heat-dissipating circuit board comprising a thermally conductive base material laminated via an agent layer, including at least a part of the projected region of the thermally conductive base material, and having a thickness of the insulating sheet more than other regions Has a small heat dissipation area.
  • the thickness of the heat dissipating circuit board is reduced in at least a part (heat dissipating region) of the projection region of the heat conductive base material. Therefore, the heat of the conductive pattern can be efficiently conducted to the heat conductive base material through the heat conductive adhesive in the thin region of the insulating sheet, and the heat dissipation effect can be significantly promoted.
  • the heat dissipation circuit board can increase the thickness of the insulating sheet in other regions of the insulating sheet by reducing the thickness of only the heat dissipation region of the insulating sheet. Therefore, the heat dissipation circuit board can suppress a decrease in insulation when it is curved outside the laminated region of the heat conductive base material.
  • the “front surface” and the “back surface” are the surfaces on which the conductive pattern of the insulating sheet is laminated as the “front surface” and the opposite side as the back surface, and do not limit the positional relationship in the usage state. .
  • the conductive pattern includes a land portion and a wiring portion connected to the land portion, and the heat dissipation region includes a projection region of the land portion.
  • the heat dissipation circuit board can significantly promote the heat dissipation of the electronic component.
  • the “land area projection area” means a part or the whole of the land area projection area. In other words, depending on the shape and characteristics of the electronic component to be mounted, it is difficult to ensure heat dissipation in the projected area of the land portion (the heat dissipation effect is not promoted even if it is connected to the heat conductive substrate via a heat conductive adhesive). Area) may occur.
  • the effect of the present invention can be achieved by reducing the thickness of the insulating sheet in the remaining region of the land projection region. . That is, a form in which a part of the projection area of the land portion is not included in the heat dissipation area is also included in the present invention.
  • the average thickness of the insulating sheet in the heat radiation region is preferably 2 ⁇ m or more and 7 ⁇ m or less.
  • the said insulating sheet has a base film and the protective film laminated
  • the base film and the protective film are preferably composed mainly of polyimide.
  • the heat dissipation circuit board can increase mechanical strength, heat resistance, and the like.
  • the “main component” means a component contained by 50% by mass or more.
  • the heat dissipating circuit board includes a plurality of the heat conductive bases, and the heat conductive bases are arranged so that the laminated surfaces of the heat conductive adhesives have different heights.
  • the insulating sheet is preferably curved between the laminated regions of the conductive base material. Since the heat dissipating circuit board can suppress a decrease in insulation (voltage resistance) when curved outside the laminated region of the heat conductive base as described above, the surface of the heat conductive base is thus formed. It is possible to arrange the insulating sheet in a curved manner while maintaining the insulating property even on the stepped surface having different heights.
  • the heat dissipating circuit board may be chamfered at the edge of the heat conductive adhesive laminated surface of the heat conductive base material. In this way, by chamfering the edge of the heat conductive adhesive lamination surface of the heat conductive base material, the heat dissipation circuit board can damage the curved portion of the insulating sheet in contact with the edge of the heat conductive base material. The insulation reliability can be further increased.
  • the heat conductive adhesive layer may contain a heat conductive filler.
  • the said heat dissipation effect is accelerated
  • the thermal conductivity of the heat conductive adhesive layer is preferably 1 W / mK or more.
  • the said heat dissipation effect is accelerated
  • a heat dissipation circuit board 10 shown in FIG. 1 and FIG. 2 includes a flexible printed wiring board 1 having flexibility and a plurality of layers laminated on the back side of the flexible printed wiring board 1 with a heat conductive adhesive layer 2 interposed therebetween.
  • the heat conductive base material 3 is mainly provided.
  • the flexible printed wiring board 1 includes an insulating sheet 4, a conductive pattern 5 laminated on the surface side of the insulating sheet 4, and a coverlay 6 laminated on the surfaces of the insulating sheet 4 and the conductive pattern 5.
  • the insulating sheet 4 of the flexible printed wiring board 1 is composed of a sheet-like member having insulating properties and flexibility.
  • the heat dissipation circuit board 10 includes a plurality of heat dissipation regions B including at least a part of the projection region A of the thermally conductive base material 3 and having a smaller thickness of the insulating sheet 4 than other regions. That is, in the insulating sheet 4, the average thickness of the heat radiation area B including at least a part of the projection area A of the heat conductive substrate 3 is smaller than the average thickness of other areas.
  • the insulating sheet 4 includes a base film 4a, a protective film 4b laminated on the back side of the base film 4a, and an adhesive layer 4c that bonds the base film 4a and the protective film 4b.
  • the heat conductive adhesive layer 2 is directly laminated on the back surface of the base film 4a. That is, the protective film 4b and the adhesive layer 4c are formed with openings for defining the heat dissipation area B, and the adhesive layer 4c and the protective film 4b are not laminated on the back surface of the base film 4a in the heat dissipation area B.
  • the thickness of the insulating sheet 4 is equal to the thickness of the base film 4a in the heat radiating region B, and the thickness of the insulating sheet 4 in the regions other than the heat radiating region B is the base film 4a, the adhesive layer 4c, and the protective film 4b. Equal to the total thickness.
  • a resin film can be used as the sheet-like member constituting the base film 4a.
  • the main component of this resin film polyimide, liquid crystal polymer, fluororesin, polyethylene terephthalate, polyethylene naphthalate and the like are preferably used, and polyimide is preferable from the viewpoint of mechanical strength, heat resistance and the like.
  • the base film 4a may include a filler, an additive, and the like.
  • the lower limit of the average thickness of the base film 4a is preferably 2 ⁇ m and more preferably 3 ⁇ m.
  • the upper limit of the average thickness of the base film 4a is preferably 7 ⁇ m, and more preferably 6 ⁇ m.
  • the protective film 4b is a sheet-like member having insulation and flexibility, and is adhered to the back side of the base film 4a.
  • the material of the protective film 4b can be the same as that of the base film 4a.
  • the lower limit of the average thickness of the protective film 4b is preferably 5 ⁇ m and more preferably 10 ⁇ m.
  • an upper limit of the average thickness of the protective film 4b 50 micrometers is preferable and 40 micrometers is more preferable.
  • the average thickness of the protective film 4b is less than the said minimum, there exists a possibility that the insulation (voltage resistance) and mechanical strength of the said heat dissipation circuit board 10 may fall.
  • the average thickness of the protective film 4b exceeds the above upper limit, the flexibility of the heat dissipation circuit board 10 may be impaired.
  • an epoxy adhesive is preferably used as the adhesive constituting the adhesive layer 4c.
  • the average thickness of the adhesive layer 4c is preferably 12.5 ⁇ m or more and 60 ⁇ m or less, for example.
  • the lower limit of the sum of the average thickness of the base film 4a and the average thickness of the protective film 4b is preferably 15 ⁇ m, and more preferably 20 ⁇ m.
  • the upper limit of the total average thickness is preferably 40 ⁇ m, and more preferably 30 ⁇ m.
  • the lower limit of the average thickness in the region other than the heat dissipation region B of the insulating sheet 4 is preferably 15 ⁇ m, and more preferably 30 ⁇ m.
  • the upper limit of the average thickness is preferably 100 ⁇ m, and more preferably 70 ⁇ m.
  • the conductive pattern 5 has a planar shape (pattern) including a plurality of land portions 5a and wiring portions 5b connected to the land portions 5a.
  • the conductive pattern 5 can be formed of a conductive material, but is preferably formed of a metal, generally copper, for example.
  • the conductive pattern 5 is formed, for example, by etching a metal layer laminated on the surface of the base film 4a.
  • the conductive pattern 5 may be directly laminated on the surface of the insulating sheet 4 or may be laminated via an adhesive applied to the surface of the insulating sheet 4.
  • each heat dissipation area B includes a projection area of each land portion 5a.
  • the entire projection area of the land portion 5a may be included in the heat dissipation area B as illustrated in FIGS. 1 and 2, or a part of the projection area may not be included in the heat dissipation area B.
  • the projection area of the land portion 5 a may be entirely included in the projection area A of the heat conductive base material 3, or only a part may be included in the projection area A of the heat conductive base material 3. However, it does not have to be included in the projection area A of the heat conductive substrate 3.
  • the land portion 5a is preferably included in the projection area A and the heat dissipation area B of the thermally conductive base material 3.
  • the lower limit of the average thickness of the conductive pattern 5 is preferably 5 ⁇ m, more preferably 8 ⁇ m.
  • the upper limit of the average thickness of the conductive pattern 5 is preferably 100 ⁇ m, more preferably 90 ⁇ m.
  • the conductivity of the flexible printed wiring board 1 may be insufficient.
  • the average thickness of the conductive pattern 5 exceeds the above upper limit, the flexibility of the flexible printed wiring board 1 may be impaired.
  • a coverlay 6 is laminated on a portion of the flexible printed wiring board 1 excluding the surface side of the land portion 5a.
  • the coverlay 6 has an insulating function and an adhesive function, and is adhered to the surfaces of the base film 4 a and the conductive pattern 5.
  • the coverlay 6 has the insulating layer 6a and the adhesive layer 6b as shown in FIG. 1, the same material as the base film 4a can be used as the insulating layer 6a, and the average thickness is the same as that of the base film 4a. be able to.
  • an adhesive which comprises the adhesive layer 6b of the coverlay 6 an epoxy adhesive etc. are used suitably, for example.
  • the average thickness of the insulating layer 6a is preferably, for example, 5 ⁇ m or more and 50 ⁇ m or less.
  • the average thickness of the adhesive layer 6b is preferably 12.5 ⁇ m or more and 60 ⁇ m or less.
  • the surface of the cover lay 6 can be colored in an arbitrary color such as green, blue, yellow, red, black, but it is preferable to be colored in white.
  • a white layer on the surface of the coverlay 6, when the light emitting diode is mounted on the land portion 5 a, the light emitted from the light emitting diode toward the flexible printed wiring board 1 is reflected, and the light utilization efficiency is increased. Can do.
  • the designability of the said heat dissipation circuit board 10 can be improved.
  • This white layer can be formed, for example, by applying a coating liquid containing a white pigment and its binder.
  • the heat dissipation circuit board 10 includes a heat conductive adhesive layer 2.
  • the heat conductive adhesive layer 2 is laminated on a region including the projection region A of the heat conductive substrate 3 on the back surface of the insulating sheet 4, and adheres the insulating sheet 4 and the heat conductive substrate 3.
  • the heat conductive adhesive layer 2 is directly laminated on the back surface of the base film 4a in the heat dissipation region B of the insulating sheet 4. That is, the heat conductive adhesive layer 2 is filled in the opening that defines the heat radiation area B of the protective film 4b and the adhesive layer 4c. Moreover, in the area
  • the heat conductive adhesive layer 2 contains an adhesive resin component and a heat conductive filler.
  • the adhesive resin component for example, polyimide, epoxy, alkyd resin, urethane resin, phenol resin, melamine resin, acrylic resin, polyamide, polyethylene, polystyrene, polypropylene, polyester, vinyl acetate resin, silicone resin, rubber and the like can be used. If an adhesive mainly composed of an acrylic resin, a silicone resin, a urethane resin, or the like is used as the adhesive resin component, the flexible printed wiring board 1 can be easily and reliably attached to the heat conductive substrate 3.
  • thermally conductive filler examples include metal oxides and metal nitrides.
  • metal oxide aluminum oxide, silicon oxide, beryllium oxide, magnesium oxide, or the like can be used. Among these, aluminum oxide is preferable from the viewpoint of electrical insulation, thermal conductivity, price, and the like.
  • metal nitride aluminum nitride, silicon nitride, boron nitride, or the like can be used. Among these, boron nitride is preferable from the viewpoint of electrical insulation, thermal conductivity, and low dielectric constant.
  • the said metal oxide and metal nitride can be used in mixture of 2 or more types.
  • the heat conductive adhesive layer 2 may contain additives, such as a hardening
  • the lower limit of the thermal conductivity of the heat conductive adhesive layer 2 is preferably 1 W / mK, and more preferably 3 W / mK.
  • the upper limit of the thermal conductivity of the heat conductive adhesive layer 2 is preferably 20 W / mK.
  • the thermal conductivity of the heat conductive adhesive layer 2 is less than the lower limit, the heat dissipation effect of the heat dissipation circuit board 10 may be insufficient.
  • the thermal conductivity of the heat conductive adhesive layer 2 exceeds the upper limit, the content of the heat conductive filler becomes excessive, and bubbles are likely to enter when the adhesive resin component and the heat conductive filler are mixed. Therefore, the withstand voltage of the heat dissipation circuit board may be reduced, and the cost may be excessive.
  • the lower limit of the average thickness (average distance between the back surface of the protective film 4b and the surface of the heat conductive substrate 3) in the region excluding the heat radiation region B of the heat conductive adhesive layer 2 is preferably 5 ⁇ m, and preferably 10 ⁇ m. More preferred.
  • the upper limit of the average thickness is preferably 100 ⁇ m, and more preferably 50 ⁇ m.
  • the minimum width d of the heat conductive adhesive layer 2 laminated on the back surface of the protective film 4b (the minimum distance between the outer edge of the projection area A and the outer edge of the heat dissipation area B of the heat conductive base material 3) is appropriately designed, It may be 0 mm.
  • the heat conductive adhesive layer 2 may be formed using 2 or more types of adhesives. Specifically, the heat conductive adhesive layer 2 is laminated on the back surface of the insulating sheet 4 and the second heat conductive adhesive layer is laminated on the back surface of the first heat conductive adhesive layer. You may have a heat conductive adhesive layer.
  • the heat conductive adhesive layer 2 is laminated on the back surface of the insulating sheet 4 and the second heat conductive adhesive layer is laminated on the back surface of the first heat conductive adhesive layer.
  • the thermally conductive base material 3 is a member having a high thermal conductivity.
  • the shape of the heat conductive base material 3 can be made into plate shape, block shape, etc., for example. Further, a plate-like member bent three-dimensionally may be used.
  • Examples of the material of the heat conductive substrate 3 include metals, ceramics, carbon, and the like. Among these, metals are preferably used.
  • the heat conductive base material 3 may have alumite on the surface.
  • the surface of the heat conductive substrate 3 is alumite-treated, whereby the durability of the heat conductive substrate 3 and the voltage resistance can be improved.
  • the average thickness of the alumite is preferably, for example, 10 ⁇ m or more and 100 ⁇ m or less.
  • the lower limit of the average thickness when the heat conductive substrate 3 is plate-shaped is preferably 0.1 mm, and more preferably 0.3 mm.
  • an upper limit of the average thickness of the heat conductive base material 3 5 mm is preferable and 3 mm is more preferable.
  • the average thickness of the heat conductive base material 3 is less than the said minimum, there exists a possibility that the intensity
  • the average thickness of the heat conductive substrate 3 exceeds the above upper limit, it may be difficult to process the heat conductive substrate 3, and the weight and volume of the heat dissipation circuit board 10 are unnecessary. May become large.
  • the lower limit of the thermal conductivity of the heat conductive substrate 3 is preferably 50 W / mK, and more preferably 100 W / mK. When the thermal conductivity of the heat conductive substrate 3 is less than the lower limit, the heat dissipation effect of the heat dissipation circuit board 10 may be insufficient.
  • the heat conductive base material 3 may have a chamfered edge of the laminated surface of the heat conductive adhesive. Thereby, when the heat-radiating circuit board 10 is bent and deformed, damage to the curved portion of the insulating sheet 4 in contact with the edge of the heat conductive base material 3 can be reduced, and insulation reliability is further improved. be able to.
  • the chamfering method is not particularly limited, and examples thereof include C surface processing and R surface processing. *
  • the flexible printed wiring board 1 does not need to be laminated
  • the flexible printed wiring board 1 and the heat conductive adhesive layer 2 may not be laminated, and there may be a region where the surface is exposed.
  • the heat-dissipating circuit board 10 includes a step of forming a laminate of the base film 4a, the conductive pattern 5, and the coverlay 6, and a protective film 4b having an opening that defines a heat-dissipating region B on the back side of the base film 4a. It can be manufactured by a manufacturing method including a process and a process of laminating the heat conductive adhesive layer 2 and the heat conductive base material 3 on the back surfaces of the base film 4a and the protective film 4b.
  • a laminated body including the base film 4a, the conductive pattern 5, and the coverlay 6 shown in FIG. 3 in this order from the back surface side is formed.
  • a metal foil is first laminated on the surface of the base film 4a directly or via an adhesive.
  • the conductive pattern 5 is formed on the metal foil laminated on the surface of the base film 4a.
  • the method for laminating the metal foil on the base film 4a is not particularly limited.
  • an adhesion method in which the metal foil is bonded with an adhesive a casting method in which a resin composition that is a material for an insulating substrate is applied on the metal foil, A laminating method or the like in which a metal foil is attached by hot pressing can be used.
  • the formation method of the conductive pattern 5 is not particularly limited, and a conventionally known etching method, for example, can be employed.
  • the coverlay 6 is laminated on the surfaces of the base film 4 a and the conductive pattern 5. At this time, an opening is provided in advance at a position corresponding to the land portion 5 a of the conductive pattern 5 of the cover lay 6.
  • the protective film 4b is laminated in a region other than the heat radiation region B including at least a part of the projection region A of the heat conductive substrate 3 in the back surface side of the base film 4a as shown in FIG. .
  • a plurality of openings for defining the heat dissipation region B are formed in a sheet in which the protective film 4b and the adhesive layer 4c are laminated, and the sheet is attached so that the adhesive layer 4c contacts the back surface of the base film 4a.
  • the heat radiation area B includes the projection area of the land portion 5a.
  • the conductive pattern 5 and the coverlay 6 may be laminated, or the protective film 4b may be laminated in the middle of the laminate formation process.
  • the heat conductive base material 3 including the heat radiating region B is filled with the heat conductive adhesive in the openings of the protective film 4b and the adhesive layer 4c. It has the process of laminating
  • FIG. These steps may be performed simultaneously, or after the step of laminating the heat conductive adhesive layer 2, the step of laminating the heat conductive substrate 3 may be performed.
  • a method of laminating the heat conductive adhesive layer 2 for example, a method by screen printing, a method of discharging with a dispenser, a method of sticking an adhesive sheet laminated on a release film, or the like can be used.
  • a method of sticking an adhesive sheet laminated on a release film for example, a method by screen printing, a method of discharging with a dispenser, a method of sticking an adhesive sheet laminated on a release film, or the like can be used.
  • an adhesive sheet When performing the lamination process of the heat conductive adhesive layer 2 and the lamination process of the heat conductive base material 3 simultaneously, it is preferable to use an adhesive sheet.
  • the lower limit of the viscosity of the thermally conductive adhesive during filling is preferably 10 Pa ⁇ s, more preferably 50 Pa ⁇ s.
  • the upper limit of the viscosity of the thermally conductive adhesive at the time of filling is preferably 100,000 Pa ⁇ s, more preferably 50000 Pa ⁇ s.
  • the heat-dissipating circuit board 10 is obtained by a method in which the heat conductive base material 3 superimposed on the back surface of the adhesive sheet is vacuum hot pressed.
  • the pressure of the hot press can be, for example, 0.1 MPa or more and 5 MPa or less. Moreover, as temperature at the time of this hot press, it can be set as 120 to 220 degreeC, for example.
  • the heat conductive adhesive layer 2 is laminated on the back surfaces of the base film 4a and the protective film 4b, and the heat conductive substrate 3 is laminated (temporarily pasted) on the back surface of the heat conductive adhesive layer 2.
  • the above-mentioned laminate in a vacuum container is pressurized at a relatively low temperature and temporarily crimped.
  • the heat conductive adhesive layer 2 is cured by further heating at a high temperature, and the heat dissipation circuit board 10 is obtained.
  • the pressure at the time of the temporary pressure bonding can be, for example, 0.05 MPa or more and 1 MPa or less.
  • compression-bonding it can be set as 70 to 120 degreeC, for example.
  • the temperature during the high-temperature heating can be, for example, 120 ° C. or more and 200 ° C. or less.
  • time of high temperature heating it can be 30 minutes or more and 600 minutes or less, for example.
  • the heat dissipating circuit board 10 includes an insulating sheet 4 laminated on the back surface side of the conductive pattern 5 and a base film 4a and a protective film 4b laminated on the back surface side of the base film 4a.
  • the thickness is reduced in at least a part of the projection area A (heat radiation area B) of the heat conductive base material 3. Therefore, the heat dissipating circuit board 10 can efficiently conduct the heat of the conductive pattern 5 to the heat conductive base material 3 in the heat dissipating region B and remarkably promote the heat dissipating effect.
  • the heat dissipation circuit board 10 has reduced the thickness of only the thermal radiation area
  • the heat dissipation circuit board 10 can remarkably accelerate the heat dissipation of the electronic component because the heat dissipation area B includes the projected area of the land portion 5a.
  • a heat dissipation circuit board 11 shown in FIG. 5 includes a flexible printed wiring board 1 having flexibility and a plurality of thermal conductivity layers laminated on the back side of the flexible printed wiring board 1 with a thermally conductive adhesive layer 2 interposed therebetween.
  • the substrate 3 mainly includes the light emitting diodes 7 mounted on the plurality of land portions 5 a of the flexible printed wiring board 1. Since the flexible printed wiring board 1, the heat conductive adhesive layer 2, and the heat conductive base material 3 are the same as those of the heat dissipation circuit board 10 of the first embodiment, the same reference numerals are given and description thereof is omitted. To do.
  • a plurality of thermally conductive base materials 3 are arranged so that the height of the laminated surface of the thermally conductive adhesive is different, and the insulating sheet 4 is a laminate of the plurality of thermally conductive base materials 3. Curved between areas.
  • the heat dissipation circuit board 11 further includes a connector 9 connected to the conductive pattern 5 of the flexible printed wiring board 1.
  • the laminated surfaces of the thermally conductive adhesives of the plurality of thermally conductive substrates 3 are parallel to each other, but these laminated surfaces are parallel in a cross section in the thickness direction (cross section of FIG. 5). Not necessarily.
  • the light emitting diode 7 is mounted on the plurality of land portions 5 a of the flexible printed wiring board 1.
  • the light emitting diode 7 is connected to the land portion 5 a by solder 8.
  • the method of connecting the light emitting diode 7 to the land portion 5a is not limited to soldering, and for example, die bonding using a conductive paste, wire bonding using a metal wire, or the like can be used.
  • the connector 9 is connected to the conductive pattern 5 by solder 8 and transmits and receives signals and power.
  • the heat dissipating circuit board 11 can suppress a decrease in insulation (voltage resistance) when bent outside the laminated region of the heat conductive base 3 as described above, the inner surface of a housing with a step, etc. Can be easily and reliably disposed.
  • the protective film is laminated on the base film via the adhesive layer, but the adhesive layer is not essential, and the protective film may be laminated directly on the base film.
  • the heat dissipating circuit board may have a single insulating sheet or a multilayer structure of three or more layers.
  • the insulating sheet is a single layer, that is, only the base film, for example, the average thickness of the heat dissipation region can be made smaller than the average thickness of other regions by reducing the thickness of the heat dissipation region by etching or the like.
  • the heat dissipation circuit board may include only one heat conductive base material. Even in the case where only one heat conductive substrate is provided, the heat dissipating circuit board can be suitably used for applications in which bending of the flexible printed wiring board is required.
  • the heat dissipation area does not necessarily include the projected area of the land portion, and the heat dissipation area may be formed at a position that does not overlap the land portion.
  • the heat dissipating circuit board forms a heat dissipating region at a position overlapping the land portion.
  • the projected region of the thermally conductive base material is wider than the heat dissipating region including the heat dissipating region, but the relationship between these regions is not limited thereto, and these regions are not limited thereto. May match. Further, the heat radiation area may overlap with only a part of the projection area of the heat conductive substrate.
  • the light emitting diode is mounted on the flexible printed wiring board, but an electronic component other than the light emitting diode may be mounted on the flexible printed wiring board.
  • the printed wiring board used in the present invention is not limited to a flexible printed wiring board, and a rigid printed wiring board may be used. Furthermore, the printed wiring board used in the present invention is not limited to the one used in the above embodiment as long as it has a land portion on the front surface and an insulating sheet on the back surface.
  • the printed wiring board may be, for example, a double-sided printed wiring board in which a conductive pattern is formed on both sides of an insulating film, or a multilayer printed wiring board in which a plurality of insulating films having a conductive pattern are laminated. Even in the case of such a double-sided printed wiring board or a multilayer printed wiring board, the heat dissipation effect can be promoted by laminating the thermally conductive base material on the back side (the side opposite to the mounting surface of the electronic component).
  • a wiring board is prepared by laminating a layer and a coverlay having an adhesive layer with an average thickness of 40 ⁇ m in this order from the back side.
  • This wiring board has a pair of land portions in which LEDs (light emitting diodes) can be mounted on a conductive pattern, and an opening is provided in the cover lay along the land portions.
  • a coverlay having an adhesive layer of 25 ⁇ m is attached by hot pressing.
  • a heat conductive base material having an average thickness of 1 mm made of aluminum is attached to a region including the heat dissipation region of the flexible printed wiring board to which the cover lay has been attached via a heat conductive adhesive sheet having an average thickness of 50 ⁇ m using a vacuum press. wear.
  • the heat conductivity of the said heat conductive adhesive sheet is 3 W / mK.
  • the LED is mounted on the land by solder reflow. After mounting the LED, the thermal conductive substrate is fixed to the predetermined mounting position while bending the portion of the flexible printed wiring board where the thermal conductive substrate is not laminated. 1 heat dissipation circuit board is obtained.
  • the heat-dissipating circuit board of No. 1 it is possible to maintain a withstand voltage of 2.5 kV or higher even after being applied to the heat conductive base material.
  • the withstand voltage is less than 2.5 kV due to damage to the base film.
  • Heat-dissipating circuit board 1 Flexible printed wiring board 2 Thermally conductive adhesive layer 3 Thermally conductive substrate 4 Insulating sheet 4a Base film 4b Protective film 4c Adhesive layer 5 Conductive pattern 5a Land part 5b Wiring part 6 Coverlay 6a Insulating layer 6b Adhesive layer 7 Light emitting diode 8 Solder 9 Connector A Projection area of thermally conductive base material B Heat dissipation area

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Structure Of Printed Boards (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
  • Laminated Bodies (AREA)

Abstract

A heat dissipating circuit board according to one embodiment of the present invention is provided with: a printed wiring board which comprises an insulating sheet and a conductive pattern that is laminated on the front surface of the insulating sheet; and a thermally conductive base which is laminated on the back surface of the insulating sheet of the printed wiring board with a thermally conductive adhesive layer being interposed therebetween. This heat dissipating circuit board has a heat dissipation region which contains at least a part of the projected area of the thermally conductive base, and in which the thickness of the insulating sheet is smaller than that in the other regions.

Description

放熱性回路基板Heat dissipation circuit board
　本発明は、放熱性回路基板に関する。本出願は、２０１５年１２月０９日出願の日本出願第２０１５－２４０５６４号に基づく優先権を主張し、前記日本出願に記載された全ての記載内容を援用するものである。 The present invention relates to a heat dissipation circuit board. This application claims priority based on Japanese Patent Application No. 2015-240564 filed on Dec. 09, 2015, and incorporates all the description content described in the above Japanese application.
　プリント配線板に実装される電子部品の中には、例えば発光ダイオード（ＬＥＤ：Ｌｉｇｈｔ　Ｅｍｉｔｔｉｎｇ　Ｄｉｏｄｅ）のように稼働時の発熱量が大きいものがある。このような高発熱性の電子部品を実装するプリント配線板では、加熱による電子部品の機能低下や回路の損傷を防ぐため、一般に放熱用の金属板等が積層される。 Some electronic components mounted on a printed wiring board have a large amount of heat generated during operation, such as a light emitting diode (LED). In a printed wiring board on which such a highly exothermic electronic component is mounted, a heat dissipating metal plate or the like is generally laminated in order to prevent deterioration of the function of the electronic component or circuit damage due to heating.
　また、電子部品の放熱効果をより高めるため、金属板とプリント配線板とを熱伝導率の高い熱伝導性接着剤で接着した回路基板（特開平６－２３２５１４号公報参照）が考案されている。 In order to further enhance the heat dissipation effect of electronic components, a circuit board (see Japanese Patent Laid-Open No. 6-232514) in which a metal plate and a printed wiring board are bonded with a heat conductive adhesive having a high heat conductivity has been devised. .
特開平６－２３２５１４号公報Japanese Patent Laid-Open No. 6-232514
　本発明の一態様に係る放熱性回路基板は、絶縁シート及びこの絶縁シートの表面側に積層される導電パターンを有するプリント配線板と、上記プリント配線板の絶縁シートの裏面側に熱伝導性接着剤層を介して積層される熱伝導性基材とを備える放熱性回路基板であって、上記熱伝導性基材の投影領域の少なくとも一部を含み、他の領域よりも絶縁シートの厚さが小さい放熱領域を有する。 A heat dissipating circuit board according to one aspect of the present invention includes a printed wiring board having an insulating sheet and a conductive pattern laminated on a front surface side of the insulating sheet, and heat conductive adhesion to the back surface side of the insulating sheet of the printed wiring board. A heat-dissipating circuit board comprising a thermally conductive base material laminated via an agent layer, including at least a part of the projected region of the thermally conductive base material, and having a thickness of the insulating sheet more than other regions Has a small heat dissipation area.
図１は、本発明の第一実施形態の放熱性回路基板を示す模式的断面図である。FIG. 1 is a schematic cross-sectional view showing a heat dissipating circuit board according to a first embodiment of the present invention. 図２は、図１の放熱性回路基板の模式的平面図である。FIG. 2 is a schematic plan view of the heat dissipation circuit board of FIG. 図３は、図１の放熱性回路基板の製造方法の一工程を示す模式的断面図である。FIG. 3 is a schematic cross-sectional view showing one step of the method of manufacturing the heat dissipation circuit board of FIG. 図４は、図１の放熱性回路基板の製造方法の図２の次の工程を示す模式的断面図である。4 is a schematic cross-sectional view showing the next step of FIG. 2 in the method for manufacturing the heat dissipating circuit board of FIG. 図５は、図１とは異なる実施形態の放熱性回路基板を示す模式的断面図である。FIG. 5 is a schematic cross-sectional view showing a heat dissipating circuit board according to an embodiment different from FIG.
　[本開示が解決しようとする課題]
　上述の金属板とプリント配線板とを熱伝導性接着剤で接着した回路基板は、金属板と電子部品（導電パターン）との間に絶縁フィルムが存在するため、この絶縁フィルムの介在によって十分な放熱効果が得られ難い。そのため、この回路基板を近年普及しつつある複数のＬＥＤを備えたＬＥＤ照明装置の回路基板として用いた場合、使用条件が制限されるという不都合がある。 [Problems to be solved by this disclosure]
In the circuit board in which the above-described metal plate and printed wiring board are bonded with a heat conductive adhesive, an insulating film exists between the metal plate and the electronic component (conductive pattern). It is difficult to obtain a heat dissipation effect. For this reason, when this circuit board is used as a circuit board of an LED lighting device having a plurality of LEDs that are becoming popular in recent years, there is a disadvantage that the use conditions are limited.
　また、上述の回路基板において、熱伝導性を向上させるために絶縁フィルムを薄型化すると、段差を有する筐体の内面等に回路基板を湾曲して配置する際などに、湾曲部分で絶縁フィルムの絶縁性が低下するおそれがある。 Further, in the above circuit board, when the insulating film is thinned in order to improve the thermal conductivity, when the circuit board is curved and arranged on the inner surface of the housing having a step, the insulating film is formed at the curved portion. Insulation properties may be reduced.
　本発明は、上述のような事情に基づいてなされたものであり、電子部品の放熱を効果的に促進でき、かつ絶縁信頼性が高い放熱性回路基板の提供を目的とする。 The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a heat dissipating circuit board that can effectively promote heat dissipation of electronic components and has high insulation reliability.
　[本開示の効果]
　本発明の一態様に係る放熱性回路基板は、電子部品の放熱を効果的に促進でき、かつ絶縁信頼性が高い回路基板を提供することができる。 [Effects of the present disclosure]
The heat dissipating circuit board according to one embodiment of the present invention can provide a circuit board that can effectively promote heat dissipation of electronic components and has high insulation reliability.
［本発明の実施形態の説明］
　本発明の一態様に係る放熱性回路基板は、絶縁シート及びこの絶縁シートの表面側に積層される導電パターンを有するプリント配線板と、上記プリント配線板の絶縁シートの裏面側に熱伝導性接着剤層を介して積層される熱伝導性基材とを備える放熱性回路基板であって、上記熱伝導性基材の投影領域の少なくとも一部を含み、他の領域よりも絶縁シートの厚さが小さい放熱領域を有する。 [Description of Embodiment of the Present Invention]
A heat dissipating circuit board according to one aspect of the present invention includes a printed wiring board having an insulating sheet and a conductive pattern laminated on a front surface side of the insulating sheet, and heat conductive adhesion to the back surface side of the insulating sheet of the printed wiring board. A heat-dissipating circuit board comprising a thermally conductive base material laminated via an agent layer, including at least a part of the projected region of the thermally conductive base material, and having a thickness of the insulating sheet more than other regions Has a small heat dissipation area.
　当該放熱性回路基板は、導電パターンの裏面側に積層される絶縁シートにおいて、熱伝導性基材の投影領域の少なくとも一部（放熱領域）で厚さが減じられている。そのため導電パターンの熱を絶縁シートの薄い領域で熱伝導性接着剤を介して熱伝導性基材に効率的に伝導し放熱効果を著しく促進することができる。また、当該放熱性回路基板は、絶縁シートの放熱領域のみの厚さを減じることで、絶縁シートにおける他の領域で絶縁シートの厚さを大きくできる。そのため、当該放熱性回路基板は、熱伝導性基材の積層領域以外で湾曲させた際の絶縁性の低下を抑制できる。 In the insulating sheet laminated on the back surface side of the conductive pattern, the thickness of the heat dissipating circuit board is reduced in at least a part (heat dissipating region) of the projection region of the heat conductive base material. Therefore, the heat of the conductive pattern can be efficiently conducted to the heat conductive base material through the heat conductive adhesive in the thin region of the insulating sheet, and the heat dissipation effect can be significantly promoted. In addition, the heat dissipation circuit board can increase the thickness of the insulating sheet in other regions of the insulating sheet by reducing the thickness of only the heat dissipation region of the insulating sheet. Therefore, the heat dissipation circuit board can suppress a decrease in insulation when it is curved outside the laminated region of the heat conductive base material.
　なお、「表面」及び「裏面」は、絶縁シートの導電パターンが積層される側を「表面」とし、その反対側を裏面とするものであって、使用状態における位置関係を限定するものではない。 The “front surface” and the “back surface” are the surfaces on which the conductive pattern of the insulating sheet is laminated as the “front surface” and the opposite side as the back surface, and do not limit the positional relationship in the usage state. .
　上記導電パターンがランド部及びこのランド部に接続する配線部を含み、上記放熱領域が、上記ランド部の投影領域を含むとよい。このようにランド部の投影領域を放熱領域が含むことにより、当該放熱性回路基板は電子部品の放熱を著しく促進することができる。なお、「ランド部の投影領域」とは、ランド部の投影領域の一部又は全体を意味する。つまり、実装する電子部品の形状や特性によっては、ランド部の投影領域において放熱性が確保され難い領域（熱伝導性基材に熱伝導性接着剤を介して接続しても放熱効果が促進されない領域）が生じる場合などがある。このような放熱性が確保され難い領域については絶縁シートの厚さを減じなくとも、ランド部の投影領域の残りの領域で絶縁シートの厚さを減ずることで本発明の効果を奏することができる。すなわち、ランド部の投影領域の一部が放熱領域に含まれない形態も本発明に含まれる。 It is preferable that the conductive pattern includes a land portion and a wiring portion connected to the land portion, and the heat dissipation region includes a projection region of the land portion. Thus, when the heat dissipation area includes the projection area of the land portion, the heat dissipation circuit board can significantly promote the heat dissipation of the electronic component. The “land area projection area” means a part or the whole of the land area projection area. In other words, depending on the shape and characteristics of the electronic component to be mounted, it is difficult to ensure heat dissipation in the projected area of the land portion (the heat dissipation effect is not promoted even if it is connected to the heat conductive substrate via a heat conductive adhesive). Area) may occur. Even if the thickness of the insulating sheet is not reduced in such a region where heat dissipation is difficult to be ensured, the effect of the present invention can be achieved by reducing the thickness of the insulating sheet in the remaining region of the land projection region. . That is, a form in which a part of the projection area of the land portion is not included in the heat dissipation area is also included in the present invention.
　上記放熱領域における絶縁シートの平均厚さとしては、２μｍ以上７μｍ以下が好ましい。このように放熱領域における絶縁シートの平均厚さを上記範囲とすることで、当該放熱性回路基板の製造効率を維持しつつ当該放熱性回路基板の放熱効果を促進することができる。 The average thickness of the insulating sheet in the heat radiation region is preferably 2 μm or more and 7 μm or less. Thus, by making the average thickness of the insulating sheet in the heat dissipation region within the above range, the heat dissipation effect of the heat dissipation circuit board can be promoted while maintaining the manufacturing efficiency of the heat dissipation circuit board.
　上記絶縁シートが、ベースフィルムと、このベースフィルムの裏面側に積層される保護フィルムとを有し、上記放熱領域において、ベースフィルムの裏面に上記熱伝導性接着剤層が直接積層されるとよい。絶縁シートをこのような構成とすることで、当該放熱性回路基板は容易かつ確実に放熱領域での絶縁シートの平均厚さを他の領域よりも小さくすることができる。 The said insulating sheet has a base film and the protective film laminated | stacked on the back surface side of this base film, and it is good in the said thermal radiation area | region that the said heat conductive adhesive layer is laminated | stacked directly on the back surface of a base film. . By setting the insulating sheet in such a configuration, the heat dissipating circuit board can easily and surely reduce the average thickness of the insulating sheet in the heat radiating region as compared with other regions.
　上記ベースフィルム及び保護フィルムがポリイミドを主成分とするとよい。このようにベースフィルム及び保護フィルムの主成分をポリイミドとすることで、当該放熱性回路基板は、機械的強度や耐熱性等を高めることができる。なお、「主成分」とは、５０質量％以上含有される成分を意味する。 The base film and the protective film are preferably composed mainly of polyimide. In this way, by using polyimide as the main component of the base film and the protective film, the heat dissipation circuit board can increase mechanical strength, heat resistance, and the like. The “main component” means a component contained by 50% by mass or more.
　当該放熱性回路基板は、複数の上記熱伝導性基材を備え、これらの熱伝導性基材が、熱伝導性接着剤の積層面の高さが異なるよう配設され、上記複数の熱伝導性基材の積層領域間で上記絶縁シートが湾曲しているとよい。当該放熱性回路基板は、上述のように熱伝導性基材の積層領域以外で湾曲させた際の絶縁性（耐電圧性）の低下を抑制できるため、このように熱伝導性基材の表面高さが異なるような段差のある面にも絶縁性を維持しつつ絶縁シートを湾曲させて配設することができる。 The heat dissipating circuit board includes a plurality of the heat conductive bases, and the heat conductive bases are arranged so that the laminated surfaces of the heat conductive adhesives have different heights. The insulating sheet is preferably curved between the laminated regions of the conductive base material. Since the heat dissipating circuit board can suppress a decrease in insulation (voltage resistance) when curved outside the laminated region of the heat conductive base as described above, the surface of the heat conductive base is thus formed. It is possible to arrange the insulating sheet in a curved manner while maintaining the insulating property even on the stepped surface having different heights.
　当該放熱性回路基板は、上記熱伝導性基材の熱伝導性接着剤積層面の縁が面取りされているとよい。このように熱伝導性基材の熱伝導性接着剤積層面の縁を面取りすることで、当該放熱性回路基板は、熱伝導性基材の縁に当接した絶縁シートの湾曲部分の損傷を低減することができ、絶縁信頼性をさらに高めることができる。 The heat dissipating circuit board may be chamfered at the edge of the heat conductive adhesive laminated surface of the heat conductive base material. In this way, by chamfering the edge of the heat conductive adhesive lamination surface of the heat conductive base material, the heat dissipation circuit board can damage the curved portion of the insulating sheet in contact with the edge of the heat conductive base material. The insulation reliability can be further increased.
　当該放熱性回路基板は、上記熱伝導性接着剤層が熱伝導性フィラーを含有するとよい。このように熱伝導性接着剤層が熱伝導性フィラーを含有することで、当該放熱性回路基板は、上述の放熱効果が促進される。 In the heat dissipation circuit board, the heat conductive adhesive layer may contain a heat conductive filler. Thus, the said heat dissipation effect is accelerated | stimulated by the said heat dissipation circuit board because a heat conductive adhesive layer contains a heat conductive filler.
　当該放熱性回路基板は、上記熱伝導性接着剤層の熱伝導率としては、１Ｗ／ｍＫ以上が好ましい。このように熱伝導性接着剤層の熱伝導率を上記下限以上とすることで、当該放熱性回路基板は、上述の放熱効果が促進される。　 In the heat dissipating circuit board, the thermal conductivity of the heat conductive adhesive layer is preferably 1 W / mK or more. Thus, the said heat dissipation effect is accelerated | stimulated by the said heat dissipation circuit board by making the heat conductivity of a heat conductive adhesive layer more than the said minimum. *
［本発明の実施形態の詳細］
　以下、本発明の各実施形態について図面を参照しつつ詳説する。 [Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
［第一実施形態］
　図１及び図２に示す放熱性回路基板１０は、可撓性を有するフレキシブルプリント配線板１と、フレキシブルプリント配線板１の裏面側に熱伝導性接着剤層２を介して積層される複数の熱伝導性基材３とを主に備える。 [First embodiment]
A heat dissipation circuit board 10 shown in FIG. 1 and FIG. 2 includes a flexible printed wiring board 1 having flexibility and a plurality of layers laminated on the back side of the flexible printed wiring board 1 with a heat conductive adhesive layer 2 interposed therebetween. The heat conductive base material 3 is mainly provided.
＜フレキシブルプリント配線板＞
　フレキシブルプリント配線板１は、絶縁シート４と、この絶縁シート４の表面側に積層される導電パターン５と、絶縁シート４及び導電パターン５の表面に積層されるカバーレイ６とを有する。 <Flexible printed wiring board>
The flexible printed wiring board 1 includes an insulating sheet 4, a conductive pattern 5 laminated on the surface side of the insulating sheet 4, and a coverlay 6 laminated on the surfaces of the insulating sheet 4 and the conductive pattern 5.
（絶縁シート）
　フレキシブルプリント配線板１の絶縁シート４は、絶縁性及び可撓性を有するシート状部材で構成されている。また、当該放熱性回路基板１０は、熱伝導性基材３の投影領域Ａの少なくとも一部を含み、他の領域よりも絶縁シート４の厚さが小さい複数の放熱領域Ｂを有する。つまり、絶縁シート４において、熱伝導性基材３の投影領域Ａの少なくとも一部を含む放熱領域Ｂの平均厚さが、他の領域の平均厚さよりも小さい。 (Insulating sheet)
The insulating sheet 4 of the flexible printed wiring board 1 is composed of a sheet-like member having insulating properties and flexibility. In addition, the heat dissipation circuit board 10 includes a plurality of heat dissipation regions B including at least a part of the projection region A of the thermally conductive base material 3 and having a smaller thickness of the insulating sheet 4 than other regions. That is, in the insulating sheet 4, the average thickness of the heat radiation area B including at least a part of the projection area A of the heat conductive substrate 3 is smaller than the average thickness of other areas.
　具体的には、絶縁シート４は、ベースフィルム４ａと、このベースフィルム４ａの裏面側に積層される保護フィルム４ｂと、ベースフィルム４ａと保護フィルム４ｂとを接着する接着層４ｃとを有する。また、放熱領域Ｂにおいて、ベースフィルム４ａの裏面には熱伝導性接着剤層２が直接積層されている。つまり、保護フィルム４ｂ及び接着層４ｃには放熱領域Ｂを確定する開口が形成され、放熱領域Ｂにおいて、ベースフィルム４ａの裏面には接着層４ｃ及び保護フィルム４ｂが積層されていない。これにより、放熱領域Ｂでは絶縁シート４の厚さはベースフィルム４ａの厚さに等しく、放熱領域Ｂ以外の領域では絶縁シート４の厚さはベースフィルム４ａ、接着層４ｃ、及び保護フィルム４ｂの合計厚さに等しい。 Specifically, the insulating sheet 4 includes a base film 4a, a protective film 4b laminated on the back side of the base film 4a, and an adhesive layer 4c that bonds the base film 4a and the protective film 4b. In the heat radiation area B, the heat conductive adhesive layer 2 is directly laminated on the back surface of the base film 4a. That is, the protective film 4b and the adhesive layer 4c are formed with openings for defining the heat dissipation area B, and the adhesive layer 4c and the protective film 4b are not laminated on the back surface of the base film 4a in the heat dissipation area B. Thereby, the thickness of the insulating sheet 4 is equal to the thickness of the base film 4a in the heat radiating region B, and the thickness of the insulating sheet 4 in the regions other than the heat radiating region B is the base film 4a, the adhesive layer 4c, and the protective film 4b. Equal to the total thickness.
　ベースフィルム４ａを構成するシート状部材としては、具体的には樹脂フィルムを採用可能である。この樹脂フィルムの主成分としては、ポリイミド、液晶ポリマー、フッ素樹脂、ポリエチレンテレフタレート、ポリエチレンナフタレート等が好適に用いられ、機械的強度や耐熱性等の観点からポリイミドが好ましい。なお、ベースフィルム４ａは、充填材、添加剤等を含んでもよい。 Specifically, a resin film can be used as the sheet-like member constituting the base film 4a. As the main component of this resin film, polyimide, liquid crystal polymer, fluororesin, polyethylene terephthalate, polyethylene naphthalate and the like are preferably used, and polyimide is preferable from the viewpoint of mechanical strength, heat resistance and the like. The base film 4a may include a filler, an additive, and the like.
　ベースフィルム４ａの平均厚さの下限としては、２μｍが好ましく、３μｍがより好ましい。一方、ベースフィルム４ａの平均厚さの上限としては、７μｍが好ましく、６μｍがより好ましい。ベースフィルム４ａの平均厚さが上記下限に満たない場合、当該放熱性回路基板１０の製造効率が低下するおそれがある。逆に、ベースフィルム４ａの平均厚さが上記上限を超える場合、当該放熱性回路基板１０の放熱効果を損なうおそれがある。 The lower limit of the average thickness of the base film 4a is preferably 2 μm and more preferably 3 μm. On the other hand, the upper limit of the average thickness of the base film 4a is preferably 7 μm, and more preferably 6 μm. When the average thickness of the base film 4a is less than the said minimum, there exists a possibility that the manufacturing efficiency of the said heat dissipation circuit board 10 may fall. On the contrary, when the average thickness of the base film 4a exceeds the upper limit, the heat dissipation effect of the heat dissipation circuit board 10 may be impaired.
　保護フィルム４ｂは、絶縁性及び可撓性を有するシート状部材であり、ベースフィルム４ａの裏面側に接着される。保護フィルム４ｂの材質は、ベースフィルム４ａと同様とすることができる。 The protective film 4b is a sheet-like member having insulation and flexibility, and is adhered to the back side of the base film 4a. The material of the protective film 4b can be the same as that of the base film 4a.
　保護フィルム４ｂの平均厚さの下限としては、５μｍが好ましく、１０μｍがより好ましい。一方、保護フィルム４ｂの平均厚さの上限としては、５０μｍが好ましく、４０μｍがより好ましい。保護フィルム４ｂの平均厚さが上記下限に満たない場合、当該放熱性回路基板１０の絶縁性（耐電圧性）や機械的強度が低下するおそれがある。逆に、保護フィルム４ｂの平均厚さが上記上限を超える場合、当該放熱性回路基板１０の可撓性を損なうおそれがある。 The lower limit of the average thickness of the protective film 4b is preferably 5 μm and more preferably 10 μm. On the other hand, as an upper limit of the average thickness of the protective film 4b, 50 micrometers is preferable and 40 micrometers is more preferable. When the average thickness of the protective film 4b is less than the said minimum, there exists a possibility that the insulation (voltage resistance) and mechanical strength of the said heat dissipation circuit board 10 may fall. Conversely, when the average thickness of the protective film 4b exceeds the above upper limit, the flexibility of the heat dissipation circuit board 10 may be impaired.
　接着層４ｃを構成する接着剤としては、例えばエポキシ系接着剤等が好適に用いられる。接着層４ｃの平均厚さは、例えば１２．５μｍ以上６０μｍ以下が好ましい。 As the adhesive constituting the adhesive layer 4c, for example, an epoxy adhesive is preferably used. The average thickness of the adhesive layer 4c is preferably 12.5 μm or more and 60 μm or less, for example.
　ベースフィルム４ａの平均厚さと保護フィルム４ｂの平均厚さとの合計の下限としては、１５μｍが好ましく、２０μｍがより好ましい。一方、上記平均厚さの合計の上限としては、４０μｍが好ましく、３０μｍがより好ましい。上記平均厚さの合計が上記下限に満たない場合、当該放熱性回路基板１０の絶縁性（耐電圧性）や機械的強度が低下するおそれがある。逆に、上記平均厚さの合計が上記上限を超える場合、当該放熱性回路基板１０の可撓性を損なうおそれがある。 The lower limit of the sum of the average thickness of the base film 4a and the average thickness of the protective film 4b is preferably 15 μm, and more preferably 20 μm. On the other hand, the upper limit of the total average thickness is preferably 40 μm, and more preferably 30 μm. When the total of the average thickness is less than the lower limit, the insulating property (voltage resistance) and mechanical strength of the heat dissipating circuit board 10 may be reduced. On the contrary, when the total of the average thickness exceeds the upper limit, the flexibility of the heat dissipation circuit board 10 may be impaired.
　絶縁シート４の放熱領域Ｂ以外の領域での平均厚さの下限としては、１５μｍが好ましく、３０μｍがより好ましい。一方、上記平均厚さの上限としては、１００μｍが好ましく、７０μｍがより好ましい。上記平均厚さが上記下限に満たない場合、当該放熱性回路基板１０の絶縁性（耐電圧性）や機械的強度が低下するおそれがある。逆に、上記平均厚さが上記上限を超える場合、当該放熱性回路基板１０の可撓性を損なうおそれがある。 The lower limit of the average thickness in the region other than the heat dissipation region B of the insulating sheet 4 is preferably 15 μm, and more preferably 30 μm. On the other hand, the upper limit of the average thickness is preferably 100 μm, and more preferably 70 μm. When the said average thickness is less than the said minimum, there exists a possibility that the insulation (voltage resistance) and mechanical strength of the said heat dissipation circuit board 10 may fall. Conversely, if the average thickness exceeds the upper limit, the flexibility of the heat dissipation circuit board 10 may be impaired.
（導電パターン）
　導電パターン５は、複数のランド部５ａ及びこれらのランド部５ａに接続する配線部５ｂを含む平面形状（パターン）を有する。導電パターン５は、導電性を有する材料で形成可能であるが、好ましくは金属、一般的には例えば銅によって形成される。導電パターン５は、例えばベースフィルム４ａの表面に積層された金属層をエッチングすることによって形成される。なお、導電パターン５は、絶縁シート４の表面に直接積層されてもよいし、絶縁シート４の表面に塗工された接着剤を介して積層されていてもよい。 (Conductive pattern)
The conductive pattern 5 has a planar shape (pattern) including a plurality of land portions 5a and wiring portions 5b connected to the land portions 5a. The conductive pattern 5 can be formed of a conductive material, but is preferably formed of a metal, generally copper, for example. The conductive pattern 5 is formed, for example, by etching a metal layer laminated on the surface of the base film 4a. The conductive pattern 5 may be directly laminated on the surface of the insulating sheet 4 or may be laminated via an adhesive applied to the surface of the insulating sheet 4.
　当該放熱性回路基板１０において、各放熱領域Ｂは、各ランド部５ａの投影領域を含む。ランド部５ａの投影領域は、図１及び図２のように全体が放熱領域Ｂに包含されてもよいし、一部が放熱領域Ｂに含まれなくてもよい。また、ランド部５ａの投影領域は、熱伝導性基材３の投影領域Ａに全体が包含されてもよいし、一部のみが熱伝導性基材３の投影領域Ａに含まれてもよいし、熱伝導性基材３の投影領域Ａに含まれなくてもよい。ただし、放熱効果を促進する観点から、ランド部５ａは、熱伝導性基材３の投影領域Ａ及び放熱領域Ｂに包含されることが好ましい。 In the heat dissipation circuit board 10, each heat dissipation area B includes a projection area of each land portion 5a. The entire projection area of the land portion 5a may be included in the heat dissipation area B as illustrated in FIGS. 1 and 2, or a part of the projection area may not be included in the heat dissipation area B. Further, the projection area of the land portion 5 a may be entirely included in the projection area A of the heat conductive base material 3, or only a part may be included in the projection area A of the heat conductive base material 3. However, it does not have to be included in the projection area A of the heat conductive substrate 3. However, from the viewpoint of promoting the heat dissipation effect, the land portion 5a is preferably included in the projection area A and the heat dissipation area B of the thermally conductive base material 3.
　上記導電パターン５の平均厚さの下限としては、５μｍが好ましく、８μｍがより好ましい。一方、導電パターン５の平均厚さの上限としては、１００μｍが好ましく、９０μｍがより好ましい。導電パターン５の平均厚さが上記下限に満たない場合、フレキシブルプリント配線板１の導通性が不十分となるおそれがある。逆に、導電パターン５の平均厚さが上記上限を超える場合、フレキシブルプリント配線板１の可撓性を損なうおそれがある。 The lower limit of the average thickness of the conductive pattern 5 is preferably 5 μm, more preferably 8 μm. On the other hand, the upper limit of the average thickness of the conductive pattern 5 is preferably 100 μm, more preferably 90 μm. When the average thickness of the conductive pattern 5 is less than the above lower limit, the conductivity of the flexible printed wiring board 1 may be insufficient. Conversely, when the average thickness of the conductive pattern 5 exceeds the above upper limit, the flexibility of the flexible printed wiring board 1 may be impaired.
（カバーレイ）
　フレキシブルプリント配線板１のランド部５ａの表面側を除いた部分には、カバーレイ６が積層される。このカバーレイ６は絶縁機能及び接着機能を有し、ベースフィルム４ａ及び導電パターン５の表面に接着される。カバーレイ６が図１に示すように絶縁層６ａと接着層６ｂとを有する場合、絶縁層６ａとしては、ベースフィルム４ａと同じ材質を用いることができ、平均厚さもベースフィルム４ａと同様とすることができる。また、カバーレイ６の接着層６ｂを構成する接着剤としては、例えばエポキシ系接着剤等が好適に用いられる。絶縁層６ａの平均厚さは、例えば５μｍ以上５０μｍ以下が好ましい。接着層６ｂの平均厚さは、例えば１２．５μｍ以上６０μｍ以下が好ましい。 (Coverlay)
A coverlay 6 is laminated on a portion of the flexible printed wiring board 1 excluding the surface side of the land portion 5a. The coverlay 6 has an insulating function and an adhesive function, and is adhered to the surfaces of the base film 4 a and the conductive pattern 5. When the coverlay 6 has the insulating layer 6a and the adhesive layer 6b as shown in FIG. 1, the same material as the base film 4a can be used as the insulating layer 6a, and the average thickness is the same as that of the base film 4a. be able to. Moreover, as an adhesive which comprises the adhesive layer 6b of the coverlay 6, an epoxy adhesive etc. are used suitably, for example. The average thickness of the insulating layer 6a is preferably, for example, 5 μm or more and 50 μm or less. For example, the average thickness of the adhesive layer 6b is preferably 12.5 μm or more and 60 μm or less.
　カバーレイ６の表面は、緑、青、黄、赤、黒など任意の色に着色することが可能であるが、中でも白色に着色されることが好ましい。例えばカバーレイ６の表面に白色層を形成することで、ランド部５ａに発光ダイオードを実装した際にフレキシブルプリント配線板１側への発光ダイオードの出射光を反射し、光線の利用効率を高めることができる。また、当該放熱性回路基板１０の意匠性を高めることができる。この白色層は、例えば白色顔料とそのバインダーとを含む塗工液の塗工等により形成することができる。 The surface of the cover lay 6 can be colored in an arbitrary color such as green, blue, yellow, red, black, but it is preferable to be colored in white. For example, by forming a white layer on the surface of the coverlay 6, when the light emitting diode is mounted on the land portion 5 a, the light emitted from the light emitting diode toward the flexible printed wiring board 1 is reflected, and the light utilization efficiency is increased. Can do. Moreover, the designability of the said heat dissipation circuit board 10 can be improved. This white layer can be formed, for example, by applying a coating liquid containing a white pigment and its binder.
＜熱伝導性接着剤層＞
　当該放熱性回路基板１０は、熱伝導性接着剤層２を備える。熱伝導性接着剤層２は、絶縁シート４の裏面の熱伝導性基材３の投影領域Ａを含む領域に積層され、絶縁シート４と熱伝導性基材３とを接着する。 <Thermal conductive adhesive layer>
The heat dissipation circuit board 10 includes a heat conductive adhesive layer 2. The heat conductive adhesive layer 2 is laminated on a region including the projection region A of the heat conductive substrate 3 on the back surface of the insulating sheet 4, and adheres the insulating sheet 4 and the heat conductive substrate 3.
　具体的には、熱伝導性接着剤層２は、絶縁シート４における放熱領域Ｂにおいて、ベースフィルム４ａの裏面に直接積層されている。つまり、熱伝導性接着剤層２は、保護フィルム４ｂ及び接着層４ｃの放熱領域Ｂを確定する開口内に充填されている。また、熱伝導性基材３の投影領域Ａのうち放熱領域Ｂを除く領域では、熱伝導性接着剤層２は保護フィルム４ｂの裏面に直接積層されている。つまり、熱伝導性基材３の投影領域Ａは、図１のように放熱領域Ｂを包含し、放熱領域Ｂよりも広い領域である。これにより、熱伝導性接着剤の保護フィルム４ｂ及び接着層４ｃの開口内への充填を容易に行うことができる。 Specifically, the heat conductive adhesive layer 2 is directly laminated on the back surface of the base film 4a in the heat dissipation region B of the insulating sheet 4. That is, the heat conductive adhesive layer 2 is filled in the opening that defines the heat radiation area B of the protective film 4b and the adhesive layer 4c. Moreover, in the area | region except the thermal radiation area | region B among the projection area | regions A of the heat conductive base material 3, the heat conductive adhesive layer 2 is directly laminated | stacked on the back surface of the protective film 4b. That is, the projection area A of the heat conductive substrate 3 includes the heat dissipation area B as shown in FIG. Thereby, the inside of the opening of the protective film 4b and the adhesive layer 4c of the heat conductive adhesive can be easily performed.
　熱伝導性接着剤層２は、接着性樹脂成分と熱伝導性フィラーとを含有する。 The heat conductive adhesive layer 2 contains an adhesive resin component and a heat conductive filler.
　接着性樹脂成分としては、例えばポリイミド、エポキシ、アルキド樹脂、ウレタン樹脂、フェノール樹脂、メラミン樹脂、アクリル樹脂、ポリアミド、ポリエチレン、ポリスチレン、ポリプロピレン、ポリエステル、酢酸ビニル樹脂、シリコーン樹脂、ゴム等が使用できる。接着性樹脂成分としてアクリル樹脂、シリコーン樹脂、ウレタン樹脂等を主成分とする粘着剤を用いれば、フレキシブルプリント配線板１を熱伝導性基材３に容易かつ確実に貼着できる。 As the adhesive resin component, for example, polyimide, epoxy, alkyd resin, urethane resin, phenol resin, melamine resin, acrylic resin, polyamide, polyethylene, polystyrene, polypropylene, polyester, vinyl acetate resin, silicone resin, rubber and the like can be used. If an adhesive mainly composed of an acrylic resin, a silicone resin, a urethane resin, or the like is used as the adhesive resin component, the flexible printed wiring board 1 can be easily and reliably attached to the heat conductive substrate 3.
　上記熱伝導性フィラーとしては、例えば金属酸化物、金属窒化物等を挙げることができる。上記金属酸化物としては、酸化アルミニウム、酸化ケイ素、酸化ベリリウム、酸化マグネシウム等を用いることができる。これらの中でも、電気絶縁性、熱伝導性、価格等の観点から酸化アルミニウムが好ましい。また、上記金属窒化物としては、窒化アルミニウム、窒化ケイ素、窒化ホウ素等を用いることができる。これらの中でも、電気絶縁性、熱伝導性及び低誘電率の観点から窒化ホウ素が好ましい。なお、上記金属酸化物及び金属窒化物は、２種以上を混合して用いることができる。 Examples of the thermally conductive filler include metal oxides and metal nitrides. As the metal oxide, aluminum oxide, silicon oxide, beryllium oxide, magnesium oxide, or the like can be used. Among these, aluminum oxide is preferable from the viewpoint of electrical insulation, thermal conductivity, price, and the like. As the metal nitride, aluminum nitride, silicon nitride, boron nitride, or the like can be used. Among these, boron nitride is preferable from the viewpoint of electrical insulation, thermal conductivity, and low dielectric constant. In addition, the said metal oxide and metal nitride can be used in mixture of 2 or more types.
　熱伝導性接着剤層２における熱伝導性フィラーの含有量の下限としては、４０体積％が好ましく、４５体積％がより好ましい。一方、熱伝導性フィラーの含有量の上限としては、８５体積％が好ましく、８０体積％がより好ましい。熱伝導性フィラーの含有量が上記下限に満たない場合、熱伝導性接着剤層２の熱伝導性が不十分となるおそれがある。逆に、熱伝導性フィラーの含有量が上記上限を超える場合、上記接着性樹脂成分と熱伝導性フィラーとの混合時に気泡が入り易くなり、当該放熱性回路基板の耐電圧性が低下するおそれがある。なお、熱伝導性接着剤層２は、熱伝導性フィラー以外に硬化剤等の添加剤を含有してもよい。 As a minimum of content of a heat conductive filler in heat conductive adhesive layer 2, 40 volume% is preferred and 45 volume% is more preferred. On the other hand, as an upper limit of content of a heat conductive filler, 85 volume% is preferable and 80 volume% is more preferable. When content of a heat conductive filler is less than the said minimum, there exists a possibility that the heat conductivity of the heat conductive adhesive layer 2 may become inadequate. On the other hand, when the content of the heat conductive filler exceeds the above upper limit, bubbles are likely to enter when the adhesive resin component and the heat conductive filler are mixed, and the voltage resistance of the heat dissipation circuit board may be reduced. There is. In addition, the heat conductive adhesive layer 2 may contain additives, such as a hardening | curing agent, in addition to a heat conductive filler.
　熱伝導性接着剤層２の熱伝導率の下限としては、１Ｗ／ｍＫが好ましく、３Ｗ／ｍＫがより好ましい。一方、熱伝導性接着剤層２の熱伝導率の上限としては、２０Ｗ／ｍＫが好ましい。熱伝導性接着剤層２の熱伝導率が上記下限に満たない場合、当該放熱性回路基板１０の放熱効果が不十分となるおそれがある。逆に、熱伝導性接着剤層２の熱伝導率が上記上限を超える場合、熱伝導性フィラーの含有量が過多となり、上記接着性樹脂成分と熱伝導性フィラーとの混合時に気泡が入り易くなって当該放熱性回路基板の耐電圧性が低下するおそれや、コストが過大となるおそれがある。 The lower limit of the thermal conductivity of the heat conductive adhesive layer 2 is preferably 1 W / mK, and more preferably 3 W / mK. On the other hand, the upper limit of the thermal conductivity of the heat conductive adhesive layer 2 is preferably 20 W / mK. When the thermal conductivity of the heat conductive adhesive layer 2 is less than the lower limit, the heat dissipation effect of the heat dissipation circuit board 10 may be insufficient. On the contrary, when the thermal conductivity of the heat conductive adhesive layer 2 exceeds the upper limit, the content of the heat conductive filler becomes excessive, and bubbles are likely to enter when the adhesive resin component and the heat conductive filler are mixed. Therefore, the withstand voltage of the heat dissipation circuit board may be reduced, and the cost may be excessive.
　熱伝導性接着剤層２の放熱領域Ｂを除く領域での平均厚さ（保護フィルム４ｂの裏面と熱伝導性基材３の表面との平均距離）の下限としては、５μｍが好ましく、１０μｍがより好ましい。一方、上記平均厚さの上限としては、１００μｍが好ましく、５０μｍがより好ましい。上記平均厚さが上記下限に満たない場合、絶縁シート４と熱伝導性基材３との接着強度が不十分となるおそれがある。逆に、上記平均厚さが上記上限を超える場合、熱伝導性接着剤層２の体積が増加しコストが嵩むおそれや、当該放熱性回路基板１０が不必要に厚くなるおそれがある。 The lower limit of the average thickness (average distance between the back surface of the protective film 4b and the surface of the heat conductive substrate 3) in the region excluding the heat radiation region B of the heat conductive adhesive layer 2 is preferably 5 μm, and preferably 10 μm. More preferred. On the other hand, the upper limit of the average thickness is preferably 100 μm, and more preferably 50 μm. When the said average thickness is less than the said minimum, there exists a possibility that the adhesive strength of the insulating sheet 4 and the heat conductive base material 3 may become inadequate. On the contrary, when the average thickness exceeds the upper limit, the volume of the heat conductive adhesive layer 2 may increase and the cost may increase, or the heat dissipation circuit board 10 may become unnecessarily thick.
　保護フィルム４ｂの裏面に積層される熱伝導性接着剤層２の最小幅ｄ（熱伝導性基材３の投影領域Ａの外縁と放熱領域Ｂの外縁との最小距離）は、適宜設計され、０ｍｍであってもよい。 The minimum width d of the heat conductive adhesive layer 2 laminated on the back surface of the protective film 4b (the minimum distance between the outer edge of the projection area A and the outer edge of the heat dissipation area B of the heat conductive base material 3) is appropriately designed, It may be 0 mm.
　なお、熱伝導性接着剤層２を２種以上の接着剤を用いて形成してもよい。具体的には、熱伝導性接着剤層２が、絶縁シート４の裏面に積層される第一熱伝導性接着剤層と、この第一熱伝導性接着剤層の裏面に積層される第二熱伝導性接着剤層とを有してもよい。このように熱伝導性接着剤層２を２層に分けて形成することで、１層目（第一熱伝導性接着剤層）の形成後、ボイドの有無を確認してから２層目（第二熱伝導性接着剤層）を形成できるため、接着剤の充填を確実にすることで熱伝導性及び接着力の低下を防止することができる。 In addition, you may form the heat conductive adhesive layer 2 using 2 or more types of adhesives. Specifically, the heat conductive adhesive layer 2 is laminated on the back surface of the insulating sheet 4 and the second heat conductive adhesive layer is laminated on the back surface of the first heat conductive adhesive layer. You may have a heat conductive adhesive layer. Thus, by forming the heat conductive adhesive layer 2 into two layers, after forming the first layer (first heat conductive adhesive layer), the second layer ( Since the second heat conductive adhesive layer) can be formed, it is possible to prevent a decrease in thermal conductivity and adhesive force by ensuring the filling of the adhesive.
＜熱伝導性基材＞
　熱伝導性基材３は、高い熱伝導率を有する部材である。熱伝導性基材３の形状は、例えば板状、ブロック状等とすることができる。また、板状部材として、立体的に屈曲させたものを用いてもよい。熱伝導性基材３の材質としては、例えば金属、セラミックス、カーボン等が挙げられ、中でも金属が好適に用いられる。熱伝導性基材３を形成する金属としては、例えばアルミニウム、マグネシウム、銅、鉄、ニッケル、モリブデン、タングステン等を用いることができる。これらの中でも伝熱性、加工性及び軽量性に優れるアルミニウム又はその合金が特に好ましい。 <Heat conductive substrate>
The thermally conductive base material 3 is a member having a high thermal conductivity. The shape of the heat conductive base material 3 can be made into plate shape, block shape, etc., for example. Further, a plate-like member bent three-dimensionally may be used. Examples of the material of the heat conductive substrate 3 include metals, ceramics, carbon, and the like. Among these, metals are preferably used. As the metal forming the heat conductive substrate 3, for example, aluminum, magnesium, copper, iron, nickel, molybdenum, tungsten, or the like can be used. Among these, aluminum or an alloy thereof excellent in heat conductivity, workability and lightness is particularly preferable.
　熱伝導性基材３の材質をアルミニウム又はアルミニウム合金とする場合、熱伝導性基材３が表面にアルマイトを有するとよい。このように熱伝導性基材３の表面をアルマイト処理することで、熱伝導性基材３の耐久性ひいては耐電圧性を高めることができる。アルマイトの平均厚さとしては、例えば１０μｍ以上１００μｍ以下が好ましい。 When the material of the heat conductive base material 3 is aluminum or an aluminum alloy, the heat conductive base material 3 may have alumite on the surface. As described above, the surface of the heat conductive substrate 3 is alumite-treated, whereby the durability of the heat conductive substrate 3 and the voltage resistance can be improved. The average thickness of the alumite is preferably, for example, 10 μm or more and 100 μm or less.
　熱伝導性基材３を板状とする場合の平均厚さの下限としては、０．１ｍｍが好ましく、０．３ｍｍがより好ましい。一方、熱伝導性基材３の平均厚さの上限としては、５ｍｍが好ましく、３ｍｍがより好ましい。熱伝導性基材３の平均厚さが上記下限に満たない場合、熱伝導性基材３の強度が不十分となるおそれがある。逆に、熱伝導性基材３の平均厚さが上記上限を超える場合、熱伝導性基材３の加工が困難になるおそれがあるほか、当該放熱性回路基板１０の重量や体積が不必要に大きくなるおそれがある。 The lower limit of the average thickness when the heat conductive substrate 3 is plate-shaped is preferably 0.1 mm, and more preferably 0.3 mm. On the other hand, as an upper limit of the average thickness of the heat conductive base material 3, 5 mm is preferable and 3 mm is more preferable. When the average thickness of the heat conductive base material 3 is less than the said minimum, there exists a possibility that the intensity | strength of the heat conductive base material 3 may become inadequate. On the contrary, when the average thickness of the heat conductive substrate 3 exceeds the above upper limit, it may be difficult to process the heat conductive substrate 3, and the weight and volume of the heat dissipation circuit board 10 are unnecessary. May become large.
　熱伝導性基材３の熱伝導率の下限としては、５０Ｗ／ｍＫが好ましく、１００Ｗ／ｍＫがより好ましい。熱伝導性基材３の熱伝導率が上記下限に満たない場合、当該放熱性回路基板１０の放熱効果が不十分となるおそれがある。 The lower limit of the thermal conductivity of the heat conductive substrate 3 is preferably 50 W / mK, and more preferably 100 W / mK. When the thermal conductivity of the heat conductive substrate 3 is less than the lower limit, the heat dissipation effect of the heat dissipation circuit board 10 may be insufficient.
　熱伝導性基材３は、熱伝導性接着剤の積層面の縁が面取りされているとよい。これにより、当該放熱性回路基板１０を湾曲変形させた際に、熱伝導性基材３の縁に当接した絶縁シート４の湾曲部分の損傷を低減することができ、絶縁信頼性をさらに高めることができる。面取りの方法としては特に限定されず、例えばＣ面加工、Ｒ面加工等が挙げられる。　 The heat conductive base material 3 may have a chamfered edge of the laminated surface of the heat conductive adhesive. Thereby, when the heat-radiating circuit board 10 is bent and deformed, damage to the curved portion of the insulating sheet 4 in contact with the edge of the heat conductive base material 3 can be reduced, and insulation reliability is further improved. be able to. The chamfering method is not particularly limited, and examples thereof include C surface processing and R surface processing. *
　なお、フレキシブルプリント配線板１は、熱伝導性基材３の表面（熱伝導性接着剤の積層面）全体に積層される必要はなく、熱伝導性基材３の表面において、図２に示すようにフレキシブルプリント配線板１及び熱伝導性接着剤層２が積層されず、表面が露出する領域が存在してもよい。 In addition, the flexible printed wiring board 1 does not need to be laminated | stacked on the whole surface (lamination surface of a heat conductive adhesive) of the heat conductive base material 3, and in the surface of the heat conductive base material 3, it shows in FIG. Thus, the flexible printed wiring board 1 and the heat conductive adhesive layer 2 may not be laminated, and there may be a region where the surface is exposed.
〔放熱性回路基板の製造方法〕
　当該放熱性回路基板１０は、ベースフィルム４ａ、導電パターン５及びカバーレイ６の積層体を形成する工程と、ベースフィルム４ａの裏面側に放熱領域Ｂを画定する開口を有する保護フィルム４ｂを積層する工程と、ベースフィルム４ａ及び保護フィルム４ｂの裏面側に熱伝導性接着剤層２及び熱伝導性基材３を積層する工程とを備える製造方法によって製造することができる。 [Manufacturing method of heat dissipation circuit board]
The heat-dissipating circuit board 10 includes a step of forming a laminate of the base film 4a, the conductive pattern 5, and the coverlay 6, and a protective film 4b having an opening that defines a heat-dissipating region B on the back side of the base film 4a. It can be manufactured by a manufacturing method including a process and a process of laminating the heat conductive adhesive layer 2 and the heat conductive base material 3 on the back surfaces of the base film 4a and the protective film 4b.
（積層体形成工程）
　積層体形成工程では、図３に示すベースフィルム４ａ、導電パターン５及びカバーレイ６を裏面側からこの順に備える積層体を形成する。具体的には、まずベースフィルム４ａの表面に直接又は接着剤を介して金属箔を積層する。次に、ベースフィルム４ａの表面に積層した金属箔に導電パターン５を形成する。この金属箔をベースフィルム４ａに積層する方法としては特に限定されず、例えば金属箔を接着剤で貼り合わせる接着法、金属箔上に絶縁性基板の材料である樹脂組成物を塗布するキャスト法、金属箔を熱プレスで貼り付けるラミネート法等を用いることができる。また、導電パターン５の形成手法も特に限定されず、従来公知の例えばエッチング法等を採用できる。 (Laminate formation process)
In the laminated body forming step, a laminated body including the base film 4a, the conductive pattern 5, and the coverlay 6 shown in FIG. 3 in this order from the back surface side is formed. Specifically, a metal foil is first laminated on the surface of the base film 4a directly or via an adhesive. Next, the conductive pattern 5 is formed on the metal foil laminated on the surface of the base film 4a. The method for laminating the metal foil on the base film 4a is not particularly limited. For example, an adhesion method in which the metal foil is bonded with an adhesive, a casting method in which a resin composition that is a material for an insulating substrate is applied on the metal foil, A laminating method or the like in which a metal foil is attached by hot pressing can be used. Moreover, the formation method of the conductive pattern 5 is not particularly limited, and a conventionally known etching method, for example, can be employed.
　導電パターン５の形成後、ベースフィルム４ａ及び導電パターン５の表面にカバーレイ６を積層する。このとき、カバーレイ６の導電パターン５のランド部５ａに対応する位置には予め開口を設けておく。 After the formation of the conductive pattern 5, the coverlay 6 is laminated on the surfaces of the base film 4 a and the conductive pattern 5. At this time, an opening is provided in advance at a position corresponding to the land portion 5 a of the conductive pattern 5 of the cover lay 6.
（保護フィルム積層工程）
　保護フィルム積層工程では、図４に示すようにベースフィルム４ａの裏面側のうち、熱伝導性基材３の投影領域Ａの少なくとも一部を含む放熱領域Ｂ以外の領域に保護フィルム４ｂを積層する。具体的には、保護フィルム４ｂ及び接着層４ｃを積層したシートに放熱領域Ｂを確定する複数の開口を形成し、接着層４ｃがベースフィルム４ａの裏面に当接するように上記シートを貼り付ける。このとき、放熱領域Ｂがランド部５ａの投影領域を含むようにする。なお、上記シートをベースフィルム４ａの裏面に積層した後に開口を形成してもよい。 (Protective film lamination process)
In the protective film laminating step, the protective film 4b is laminated in a region other than the heat radiation region B including at least a part of the projection region A of the heat conductive substrate 3 in the back surface side of the base film 4a as shown in FIG. . Specifically, a plurality of openings for defining the heat dissipation region B are formed in a sheet in which the protective film 4b and the adhesive layer 4c are laminated, and the sheet is attached so that the adhesive layer 4c contacts the back surface of the base film 4a. At this time, the heat radiation area B includes the projection area of the land portion 5a. In addition, you may form opening, after laminating | stacking the said sheet | seat on the back surface of the base film 4a.
　なお、積層体形成工程と保護フィルム積層工程とは、必ずしもこの順に行う必要はなく、順序を入れ替えて行ってもよいし、同時に行ってもよい。つまり、ベースフィルム４ａに保護フィルム４ｂを積層してから導電パターン５及びカバーレイ６を積層してもよいし、積層体形成工程の途中で保護フィルム４ｂを積層してもよい。 In addition, it is not necessary to perform a laminated body formation process and a protective film lamination process in this order, you may replace the order and may perform simultaneously. That is, after the protective film 4b is laminated on the base film 4a, the conductive pattern 5 and the coverlay 6 may be laminated, or the protective film 4b may be laminated in the middle of the laminate formation process.
（熱伝導性接着剤層及び熱伝導性基材積層工程）
　熱伝導性接着剤層及び熱伝導性基材積層工程は、保護フィルム４ｂ及び接着層４ｃの開口に熱伝導性接着剤を充填しつつ、放熱領域Ｂを含む熱伝導性基材３の積層領域（投影領域Ａ）に熱伝導性接着剤層２を積層する工程と、熱伝導性接着剤層２の裏面に熱伝導性基材３を積層する工程とを有する。これらの工程は、同時に行ってもよく、熱伝導性接着剤層２の積層工程後に、熱伝導性基材３の積層工程を行ってもよい。 (Heat conductive adhesive layer and heat conductive base material lamination process)
In the heat conductive adhesive layer and the heat conductive base material laminating step, the heat conductive base material 3 including the heat radiating region B is filled with the heat conductive adhesive in the openings of the protective film 4b and the adhesive layer 4c. It has the process of laminating | stacking the heat conductive adhesive layer 2 in (projection area | region A), and the process of laminating | stacking the heat conductive base material 3 on the back surface of the heat conductive adhesive layer 2. FIG. These steps may be performed simultaneously, or after the step of laminating the heat conductive adhesive layer 2, the step of laminating the heat conductive substrate 3 may be performed.
　熱伝導性接着剤層２の積層方法としては、例えばスクリーン印刷による方法、ディスペンサで吐出する方法、離型フィルムに積層した接着シートを貼付する方法等を用いることができる。熱伝導性接着剤層２の積層工程と熱伝導性基材３の積層工程とを同時に行う場合は、接着シートを用いることが好ましい。 As a method of laminating the heat conductive adhesive layer 2, for example, a method by screen printing, a method of discharging with a dispenser, a method of sticking an adhesive sheet laminated on a release film, or the like can be used. When performing the lamination process of the heat conductive adhesive layer 2 and the lamination process of the heat conductive base material 3 simultaneously, it is preferable to use an adhesive sheet.
　充填時の熱伝導性接着剤の粘度の下限としては、１０Ｐａ・ｓが好ましく、５０Ｐａ・ｓがより好ましい。一方、充填時の熱伝導性接着剤の粘度の上限としては、１０００００Ｐａ・ｓが好ましく、５００００Ｐａ・ｓがより好ましい。充填時の熱伝導性接着剤の粘度が上記下限に満たない場合、熱伝導性接着剤を硬化させる前に熱伝導性接着剤が流動して充填性が低下するおそれがある。逆に、充填時の熱伝導性接着剤の粘度が上記上限を超える場合、熱伝導性接着剤の保護フィルム４ｂ及び接着層４ｃの開口への充填が不十分となるおそれがある。 The lower limit of the viscosity of the thermally conductive adhesive during filling is preferably 10 Pa · s, more preferably 50 Pa · s. On the other hand, the upper limit of the viscosity of the thermally conductive adhesive at the time of filling is preferably 100,000 Pa · s, more preferably 50000 Pa · s. When the viscosity of the heat conductive adhesive at the time of filling is less than the above lower limit, the heat conductive adhesive may flow before the heat conductive adhesive is cured, and the fillability may be lowered. On the contrary, when the viscosity of the heat conductive adhesive at the time of filling exceeds the upper limit, the heat conductive adhesive may not be sufficiently filled into the openings of the protective film 4b and the adhesive layer 4c.
　熱伝導性接着剤層２の積層工程と熱伝導性基材３の積層工程とを同時に行う場合、ベースフィルム４ａ及び保護フィルム４ｂの裏面に熱伝導性接着剤シートを重ね、さらにこの熱伝導性接着剤シートの裏面に熱伝導性基材３を重ねたものを真空熱プレスする方法により、当該放熱性回路基板１０が得られる。 When the lamination process of the heat conductive adhesive layer 2 and the lamination process of the heat conductive base material 3 are performed at the same time, a heat conductive adhesive sheet is stacked on the back surfaces of the base film 4a and the protective film 4b, and this heat conductivity is further increased. The heat-dissipating circuit board 10 is obtained by a method in which the heat conductive base material 3 superimposed on the back surface of the adhesive sheet is vacuum hot pressed.
　上記熱プレスの圧力としては、例えば０．１ＭＰａ以上５ＭＰａ以下とすることができる。また、この熱プレス時の温度としては、例えば１２０℃以上２２０℃以下とすることができる。 The pressure of the hot press can be, for example, 0.1 MPa or more and 5 MPa or less. Moreover, as temperature at the time of this hot press, it can be set as 120 to 220 degreeC, for example.
　また、熱伝導性基材３の積層方法としては、以下のような手順も可能である。まずベースフィルム４ａ及び保護フィルム４ｂの裏面に熱伝導性接着剤層２を積層し、この熱伝導性接着剤層２の裏面に熱伝導性基材３を積層（仮貼り）する。その後、例えば真空容器中で上記積層したものを比較的低温で加圧し、仮圧着する。仮圧着後、さらに高温で加熱することで熱伝導性接着剤層２が硬化し、当該放熱性回路基板１０が得られる。 Further, as a method of laminating the heat conductive substrate 3, the following procedure is also possible. First, the heat conductive adhesive layer 2 is laminated on the back surfaces of the base film 4a and the protective film 4b, and the heat conductive substrate 3 is laminated (temporarily pasted) on the back surface of the heat conductive adhesive layer 2. After that, for example, the above-mentioned laminate in a vacuum container is pressurized at a relatively low temperature and temporarily crimped. After the temporary pressure bonding, the heat conductive adhesive layer 2 is cured by further heating at a high temperature, and the heat dissipation circuit board 10 is obtained.
　上記仮圧着時の圧力としては、例えば０．０５ＭＰａ以上１ＭＰａ以下とすることができる。また、この仮圧着時の温度としては、例えば７０℃以上１２０℃以下とすることができる。さらに、上記高温加熱時の温度としては、例えば１２０℃以上２００℃以下とすることができる。また、高温加熱の時間としては、例えば３０分以上６００分以下とすることができる。 The pressure at the time of the temporary pressure bonding can be, for example, 0.05 MPa or more and 1 MPa or less. Moreover, as temperature at the time of this temporary crimping | compression-bonding, it can be set as 70 to 120 degreeC, for example. Furthermore, the temperature during the high-temperature heating can be, for example, 120 ° C. or more and 200 ° C. or less. Moreover, as time of high temperature heating, it can be 30 minutes or more and 600 minutes or less, for example.
＜利点＞
　当該放熱性回路基板１０は、導電パターン５の裏面側に積層される絶縁シート４が、ベースフィルム４ａと、このベースフィルム４ａの裏面側に積層される保護フィルム４ｂとを有し、ベースフィルム４ａの裏面に熱伝導性接着剤層２が直接積層されることで熱伝導性基材３の投影領域Ａの少なくとも一部（放熱領域Ｂ）で厚さが減じられている。そのため、当該放熱性回路基板１０は、導電パターン５の熱を放熱領域Ｂにおいて熱伝導性基材３に効率的に伝導し放熱効果を著しく促進することができる。また、当該放熱性回路基板１０は、絶縁シート４の放熱領域Ｂのみの厚さを減じているので、絶縁シート４における他の領域での絶縁シート４の厚さが比較的大きい。そのため、当該放熱性回路基板１０は、熱伝導性基材３の積層領域以外で湾曲させた際の絶縁性の低下を抑制できる。 <Advantages>
The heat dissipating circuit board 10 includes an insulating sheet 4 laminated on the back surface side of the conductive pattern 5 and a base film 4a and a protective film 4b laminated on the back surface side of the base film 4a. By directly laminating the heat conductive adhesive layer 2 on the back surface, the thickness is reduced in at least a part of the projection area A (heat radiation area B) of the heat conductive base material 3. Therefore, the heat dissipating circuit board 10 can efficiently conduct the heat of the conductive pattern 5 to the heat conductive base material 3 in the heat dissipating region B and remarkably promote the heat dissipating effect. Moreover, since the said heat dissipation circuit board 10 has reduced the thickness of only the thermal radiation area | region B of the insulating sheet 4, the thickness of the insulating sheet 4 in the other area | region in the insulating sheet 4 is comparatively large. Therefore, the heat dissipation circuit board 10 can suppress a decrease in insulation when it is bent outside the laminated region of the heat conductive base material 3.
　また、当該放熱性回路基板１０は、放熱領域Ｂが上記ランド部５ａの投影領域を含むことにより、電子部品の放熱を著しく促進することができる。 In addition, the heat dissipation circuit board 10 can remarkably accelerate the heat dissipation of the electronic component because the heat dissipation area B includes the projected area of the land portion 5a.
［第二実施形態］
　図５に示す放熱性回路基板１１は、可撓性を有するフレキシブルプリント配線板１と、フレキシブルプリント配線板１の裏面側に熱伝導性接着剤層２を介して積層される複数の熱伝導性基材３と、フレキシブルプリント配線板１の複数のランド部５ａに実装される発光ダイオード７とを主に備える。フレキシブルプリント配線板１、熱伝導性接着剤層２、及び熱伝導性基材３は、上記第一実施形態の放熱性回路基板１０と同様であるため、同一の符号を付して説明を省略する。 [Second Embodiment]
A heat dissipation circuit board 11 shown in FIG. 5 includes a flexible printed wiring board 1 having flexibility and a plurality of thermal conductivity layers laminated on the back side of the flexible printed wiring board 1 with a thermally conductive adhesive layer 2 interposed therebetween. The substrate 3 mainly includes the light emitting diodes 7 mounted on the plurality of land portions 5 a of the flexible printed wiring board 1. Since the flexible printed wiring board 1, the heat conductive adhesive layer 2, and the heat conductive base material 3 are the same as those of the heat dissipation circuit board 10 of the first embodiment, the same reference numerals are given and description thereof is omitted. To do.
　当該放熱性回路基板１１は、複数の熱伝導性基材３が、熱伝導性接着剤の積層面の高さが異なるよう配設され、絶縁シート４が複数の熱伝導性基材３の積層領域間で湾曲している。また、当該放熱性回路基板１１は、フレキシブルプリント配線板１の導電パターン５に接続されるコネクタ９をさらに備える。なお、図５では、複数の熱伝導性基材３の熱伝導性接着剤の積層面が平行となっているが、これらの積層面は厚さ方向の断面（図５の断面）視で平行でなくてもよい。 In the heat dissipation circuit board 11, a plurality of thermally conductive base materials 3 are arranged so that the height of the laminated surface of the thermally conductive adhesive is different, and the insulating sheet 4 is a laminate of the plurality of thermally conductive base materials 3. Curved between areas. The heat dissipation circuit board 11 further includes a connector 9 connected to the conductive pattern 5 of the flexible printed wiring board 1. In FIG. 5, the laminated surfaces of the thermally conductive adhesives of the plurality of thermally conductive substrates 3 are parallel to each other, but these laminated surfaces are parallel in a cross section in the thickness direction (cross section of FIG. 5). Not necessarily.
＜発光ダイオード＞
　発光ダイオード７は、フレキシブルプリント配線板１の複数のランド部５ａに実装される。この発光ダイオード７としては、多色発光タイプ又は単色発光タイプで、チップ型又は合成樹脂等でパッケージされた表面実装型の発光ダイオードを用いることができる。発光ダイオード７は、半田８によってランド部５ａへ接続されている。ただし、発光ダイオード７のランド部５ａへの接続方法は半田付けに限定されず、例えば導電性ペーストを用いたダイボンディング、金属線を用いたワイヤボンディング等も用いることができる。 <Light emitting diode>
The light emitting diode 7 is mounted on the plurality of land portions 5 a of the flexible printed wiring board 1. As the light-emitting diode 7, a multi-color light-emitting type or a single-color light-emitting type, and a surface-mounted light-emitting diode packaged with a chip type or a synthetic resin can be used. The light emitting diode 7 is connected to the land portion 5 a by solder 8. However, the method of connecting the light emitting diode 7 to the land portion 5a is not limited to soldering, and for example, die bonding using a conductive paste, wire bonding using a metal wire, or the like can be used.
＜コネクタ＞
　コネクタ９は、導電パターン５に半田８によって接続されており、信号や電力の送受信を行う。 <Connector>
The connector 9 is connected to the conductive pattern 5 by solder 8 and transmits and receives signals and power.
＜利点＞
　当該放熱性回路基板１１は、上述のように熱伝導性基材３の積層領域以外で湾曲させた際の絶縁性（耐電圧性）の低下を抑制できるため、段差のある筐体の内面等に容易かつ確実に配設することができる。 <Advantages>
Since the heat dissipating circuit board 11 can suppress a decrease in insulation (voltage resistance) when bent outside the laminated region of the heat conductive base 3 as described above, the inner surface of a housing with a step, etc. Can be easily and reliably disposed.
［その他の実施形態］
　今回開示された実施の形態は全ての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記実施形態の構成に限定されるものではなく、特許請求の範囲によって示され、特許請求の範囲と均等の意味及び範囲内での全ての変更が含まれることが意図される。 [Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The
　上記実施形態では、絶縁シートにおいて、接着層を介して保護フィルムをベースフィルムに積層したが、接着層は必須ではなく、保護フィルムを直接ベースフィルムに積層してもよい。 In the above embodiment, in the insulating sheet, the protective film is laminated on the base film via the adhesive layer, but the adhesive layer is not essential, and the protective film may be laminated directly on the base film.
　さらに、当該放熱性回路基板は、絶縁シートが単層でもよく、３層以上の多層構造でもよい。絶縁シートが単層、つまりベースフィルムのみである場合、例えば放熱領域の厚さをエッチング等により減ずることで、放熱領域の平均厚さを他の領域の平均厚さよりも小さくすることができる。 Further, the heat dissipating circuit board may have a single insulating sheet or a multilayer structure of three or more layers. When the insulating sheet is a single layer, that is, only the base film, for example, the average thickness of the heat dissipation region can be made smaller than the average thickness of other regions by reducing the thickness of the heat dissipation region by etching or the like.
　また、当該放熱性回路基板は、熱伝導性基材を１つのみ備えてもよい。熱伝導性基材を１つのみ備える場合でも、当該放熱性回路基板は、フレキシブルプリント配線板の湾曲が求められる用途に好適に使用することができる。 Further, the heat dissipation circuit board may include only one heat conductive base material. Even in the case where only one heat conductive substrate is provided, the heat dissipating circuit board can be suitably used for applications in which bending of the flexible printed wiring board is required.
　さらに、当該放熱性回路基板は、放熱領域が必ずしもランド部の投影領域を含む必要はなく、ランド部と重ならない位置に放熱領域を形成してもよい。ただし、電子部品の放熱効果の観点からは、当該放熱性回路基板は、ランド部と重なる位置に放熱領域を形成することが好ましい。 Further, in the heat dissipation circuit board, the heat dissipation area does not necessarily include the projected area of the land portion, and the heat dissipation area may be formed at a position that does not overlap the land portion. However, from the viewpoint of the heat dissipation effect of the electronic component, it is preferable that the heat dissipating circuit board forms a heat dissipating region at a position overlapping the land portion.
　また、図１の放熱性回路基板では、熱伝導性基材の投影領域が放熱領域を包含する放熱領域よりも広い領域としたが、これらの領域の関係はこれに限定されず、これらの領域が一致してもよい。また、放熱領域が熱伝導性基材の投影領域の一部のみと重複するものであってもよい。 Further, in the heat dissipating circuit board of FIG. 1, the projected region of the thermally conductive base material is wider than the heat dissipating region including the heat dissipating region, but the relationship between these regions is not limited thereto, and these regions are not limited thereto. May match. Further, the heat radiation area may overlap with only a part of the projection area of the heat conductive substrate.
　さらに、上記実施形態では発光ダイオードをフレキシブルプリント配線板に実装したが、発光ダイオード以外の電子部品をフレキシブルプリント配線板に実装してもよい。 Furthermore, in the above embodiment, the light emitting diode is mounted on the flexible printed wiring board, but an electronic component other than the light emitting diode may be mounted on the flexible printed wiring board.
　また、本発明で用いるプリント配線板は、可撓性を有するフレキシブルプリント配線板に限定されず、リジッドのプリント配線板を用いてもよい。さらに、本発明で用いるプリント配線板は、表面にランド部を有し、裏面に絶縁シートを有するものであれば上記実施形態で使用したものに限定されない。上記プリント配線板は、例えば絶縁フィルムの両面に導電パターンが形成された両面プリント配線板や、導電パターンを有する複数の絶縁フィルムが積層された多層プリント配線板であってもよい。このような両面プリント配線板や多層プリント配線板の場合でも、裏面側（電子部品の実装面と反対側）に熱伝導性基材を積層することで、放熱効果を促進することができる。 The printed wiring board used in the present invention is not limited to a flexible printed wiring board, and a rigid printed wiring board may be used. Furthermore, the printed wiring board used in the present invention is not limited to the one used in the above embodiment as long as it has a land portion on the front surface and an insulating sheet on the back surface. The printed wiring board may be, for example, a double-sided printed wiring board in which a conductive pattern is formed on both sides of an insulating film, or a multilayer printed wiring board in which a plurality of insulating films having a conductive pattern are laminated. Even in the case of such a double-sided printed wiring board or a multilayer printed wiring board, the heat dissipation effect can be promoted by laminating the thermally conductive base material on the back side (the side opposite to the mounting surface of the electronic component).
　以下、実施例によって本発明をさらに具体的に説明するが、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.
　［Ｎｏ．１］
　まず、ポリイミドを主成分とする平均厚さ５μｍのベースフィルムと、銅箔製の平均厚さ３５μｍの導電パターンと、平均厚さ２０μｍの白色層、ポリイミドを主成分とする平均厚さ１３μｍの絶縁層、及び平均厚さ４０μｍの接着層を有するカバーレイとを裏面側からこの順に積層した配線板を用意する。この配線板は導電パターンにＬＥＤ（発光ダイオード）が実装可能な１対のランド部を有し、このランド部に沿ってカバーレイに開口が設けられている。 [No. 1]
First, a base film having an average thickness of 5 μm mainly composed of polyimide, a conductive pattern made of copper foil having an average thickness of 35 μm, a white layer having an average thickness of 20 μm, and an insulation having an average thickness of 13 μm mainly composed of polyimide. A wiring board is prepared by laminating a layer and a coverlay having an adhesive layer with an average thickness of 40 μm in this order from the back side. This wiring board has a pair of land portions in which LEDs (light emitting diodes) can be mounted on a conductive pattern, and an opening is provided in the cover lay along the land portions.
　次に、上記配線板の裏面（平均厚さ５μｍのベースフィルムの裏面）のうちランド部の投影領域を含む放熱領域以外に、ポリイミドを主成分とする平均厚さ２５μｍの保護フィルム、及び平均厚さ２５μｍの接着層を有するカバーレイを熱プレスで貼り付ける。このカバーレイを貼り付けたフレキシブルプリント配線板の上記放熱領域を含む領域に、平均厚さ５０μｍの熱伝導性接着シートを介してアルミニウム製の平均厚み１ｍｍの熱伝導性基材を真空プレスで貼り付ける。なお、上記熱伝導性接着シートの熱伝導率は３Ｗ／ｍＫである。 Next, in addition to the heat dissipation area including the projected area of the land portion on the back surface of the wiring board (the back surface of the base film having an average thickness of 5 μm), a protective film having an average thickness of 25 μm mainly composed of polyimide, and the average thickness A coverlay having an adhesive layer of 25 μm is attached by hot pressing. A heat conductive base material having an average thickness of 1 mm made of aluminum is attached to a region including the heat dissipation region of the flexible printed wiring board to which the cover lay has been attached via a heat conductive adhesive sheet having an average thickness of 50 μm using a vacuum press. wear. In addition, the heat conductivity of the said heat conductive adhesive sheet is 3 W / mK.
　その後、上記ランド部にＬＥＤを半田リフローにより実装する。ＬＥＤの実装後、所定の取付位置に対し、フレキシブルプリント配線板の熱伝導性基材が積層されていない部分を曲げながら熱伝導性基材を固定し、Ｎｏ．１の放熱性回路基板を得る。 After that, the LED is mounted on the land by solder reflow. After mounting the LED, the thermal conductive substrate is fixed to the predetermined mounting position while bending the portion of the flexible printed wiring board where the thermal conductive substrate is not laminated. 1 heat dissipation circuit board is obtained.
　［Ｎｏ．２］
　裏面側のカバーレイ（保護フィルム）を積層しなかったこと以外はＮｏ．１と同様にしてＮｏ．２の放熱性回路基板を得る。 [No. 2]
No. except that the back side coverlay (protective film) was not laminated. No. 1 as in No. 1. 2 heat dissipation circuit board is obtained.
　［評価］
　上記Ｎｏ．１，２の放熱性回路基板について、曲げた部分のフレキシブルプリント配線板の裏面を熱伝導性基材の縁（端部）に繰り返し当て、その後の耐電圧性能を測定した。　 [Evaluation]
No. above. About the heat-radiating circuit board of 1 and 2, the back surface of the flexible printed wiring board of the bent part was repeatedly applied to the edge (edge part) of the heat conductive base material, and the subsequent withstand voltage performance was measured.
　Ｎｏ．１の放熱性回路基板では、熱伝導性基材へ当てた後も２．５ｋＶ以上の耐電圧を保持できるが、Ｎｏ．２の放熱性回路基板では、ベースフィルムの損傷により、耐電圧が２．５ｋＶ未満となる。 No. In the heat-dissipating circuit board of No. 1, it is possible to maintain a withstand voltage of 2.5 kV or higher even after being applied to the heat conductive base material. In the heat dissipating circuit board 2, the withstand voltage is less than 2.5 kV due to damage to the base film.
１０、１１　放熱性回路基板
１　フレキシブルプリント配線板　　２　熱伝導性接着剤層
３　熱伝導性基材　　４　絶縁シート
４ａ　ベースフィルム　　４ｂ　保護フィルム　　４ｃ　接着層
５　導電パターン　　５ａ　ランド部　　５ｂ　配線部
６　カバーレイ　　６ａ　絶縁層　　６ｂ　接着層
７　発光ダイオード　　８　半田　　９　コネクタ
Ａ　熱伝導性基材の投影領域　　Ｂ　放熱領域 10, 11 Heat-dissipating circuit board 1 Flexible printed wiring board 2 Thermally conductive adhesive layer 3 Thermally conductive substrate 4 Insulating sheet 4a Base film 4b Protective film 4c Adhesive layer 5 Conductive pattern 5a Land part 5b Wiring part 6 Coverlay 6a Insulating layer 6b Adhesive layer 7 Light emitting diode 8 Solder 9 Connector A Projection area of thermally conductive base material B Heat dissipation area

Claims (9)

  1. 　絶縁シート及びこの絶縁シートの表面側に積層される導電パターンを有するプリント配線板と、
    　上記プリント配線板の絶縁シートの裏面側に熱伝導性接着剤層を介して積層される熱伝導性基材と
    　を備える放熱性回路基板であって、
    　上記熱伝導性基材の投影領域の少なくとも一部を含み、他の領域よりも絶縁シートの厚さが小さい放熱領域を有する放熱性回路基板。     An insulating sheet and a printed wiring board having a conductive pattern laminated on the surface side of the insulating sheet;
    A heat dissipating circuit board comprising: a heat conductive base material laminated via a heat conductive adhesive layer on the back side of the insulating sheet of the printed wiring board,
    A heat dissipating circuit board including a heat dissipating region including at least a part of a projected region of the heat conductive base material and having a smaller insulating sheet thickness than other regions.
  2. 　上記導電パターンがランド部及びこのランド部に接続する配線部を含み、
    　上記放熱領域が、上記ランド部の投影領域を含む請求項１に記載の放熱性回路基板。     The conductive pattern includes a land portion and a wiring portion connected to the land portion,
    The heat dissipation circuit board according to claim 1, wherein the heat dissipation area includes a projection area of the land portion.
  3. 　上記放熱領域における絶縁シートの平均厚さが２μｍ以上７μｍ以下である請求項１又は請求項２に記載の放熱性回路基板。 The heat dissipation circuit board according to claim 1 or 2, wherein an average thickness of the insulating sheet in the heat dissipation region is 2 µm or more and 7 µm or less.
  4. 　上記絶縁シートが、ベースフィルムと、このベースフィルムの裏面側に積層される保護フィルムとを有し、
    　上記放熱領域において、ベースフィルムの裏面に上記熱伝導性接着剤層が直接積層される請求項１、請求項２又は請求項３に記載の放熱性回路基板。     The insulating sheet has a base film and a protective film laminated on the back side of the base film,
    The heat dissipation circuit board according to claim 1, wherein the heat conductive adhesive layer is directly laminated on the back surface of the base film in the heat dissipation region.
  5. 　上記ベースフィルム及び保護フィルムがポリイミドを主成分とする請求項４に記載の放熱性回路基板。 The heat-radiating circuit board according to claim 4, wherein the base film and the protective film are mainly composed of polyimide.
  6. 　複数の上記熱伝導性基材を備え、
    　これらの熱伝導性基材が、熱伝導性接着剤の積層面の高さが異なるよう配設され、
    　上記複数の熱伝導性基材の積層領域間で上記絶縁シートが湾曲している請求項１から請求項５のいずれか１項に記載の放熱性回路基板。     Comprising a plurality of the above heat conductive substrates,
    These heat conductive base materials are arranged so that the height of the laminated surface of the heat conductive adhesive is different,
    The heat dissipating circuit board according to any one of claims 1 to 5, wherein the insulating sheet is curved between the laminated regions of the plurality of heat conductive substrates.
  7. 　上記熱伝導性基材の熱伝導性接着剤積層面の縁が面取りされている請求項１から請求項６のいずれか１項に記載の放熱性回路基板。 The heat dissipating circuit board according to any one of claims 1 to 6, wherein an edge of the heat conductive adhesive laminated surface of the heat conductive base material is chamfered.
  8. 　上記熱伝導性接着剤層が熱伝導性フィラーを含有する請求項１から請求項７のいずれか１項に記載の放熱性回路基板。 The heat dissipation circuit board according to any one of claims 1 to 7, wherein the heat conductive adhesive layer contains a heat conductive filler.
  9. 　上記熱伝導性接着剤層の熱伝導率が１Ｗ／ｍＫ以上である請求項１から請求項８のいずれか１項に記載の放熱性回路基板。 The heat dissipation circuit board according to any one of claims 1 to 8, wherein the heat conductivity of the heat conductive adhesive layer is 1 W / mK or more.
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