JP2017224394A - Flexible substrate and frustoconical circuit board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a truncated cone-shaped flexible substrate capable of arranging an LED element at a position following the truncated cone side surface shape in an LED lighting device or an LED display device having a truncated cone side surface shape light emitting surface. SOLUTION: A resin substrate 11 and a metal wiring portion 13 formed on one surface of the resin substrate 11 are provided, and the resin substrate 11 is flexible and has a truncated cone side surface developed. A flexible substrate 1 made of a resin film having a fan-shaped outer shape is formed, and a truncated cone-shaped circuit board 1A is formed by using the flexible substrate 1. [Selection diagram] Fig. 2

Description

  The present invention relates to a flexible substrate, a frustoconical circuit board using the flexible substrate, and a frustoconical LED light source.

  In recent years, LED lighting devices and LED display devices using LED elements as light sources have been rapidly spread. In these LED devices, in order to mount an LED element as a light source, various LED element substrates each including a support substrate and a wiring portion are used. Conventionally, a rigid substrate made of a flat plate having rigidity such as a glass epoxy plate has been widely used as such an LED element substrate (see Patent Document 1).

  Here, in the case where an LED element is used as a light source of an illumination device or a display device having a light emitting surface constituted by a curved surface, uniform light emission is obtained from the entire light emitting surface to obtain a preferable lighting effect or display quality. In addition, it is required to uniformly arrange the LED elements at a position following the shape of the light emitting curved surface, that is, at a position equidistant from the curved surface. However, since the rigid substrate is a flat plate that does not have flexibility, even if a plurality of substrates are combined, the rigid substrate is arranged at a position that follows the shape of such a light-emitting curved surface only approximately. It is not possible. Further, even in the case of such an approximate arrangement, a connector for combining a plurality of rigid boards is essential, which is extremely disadvantageous in terms of production cost and final product design.

  As a means for improving the followability of the LED element to the light emission curved surface, for example, a flexible substrate (see Patent Document 2) in which a metal circuit is formed on a flexible resin substrate such as a polyester-based resin sheet is used. Conceivable. In addition to being able to flexibly follow curved surfaces, flexible substrates have higher design flexibility than conventional rigid substrates, and can be mass-produced on a roll-to-roll basis. Is also relatively superior. For this reason, further expansion of demand is expected in the future.

  By adopting the flexible substrate, for example, for a curved surface such as a side surface of a cylinder, it is possible to configure a light source that smoothly follows the curved surface. However, for example, as shown in FIG. 1, when a light source of a lighting device (for example, a ceiling light or the like) having a light emitting surface along a frustoconical side surface is constituted by an LED element, it is usually a rectangular flat surface. A plurality of flexible substrates having a shape must be combined and separated on a curved surface, and it is still difficult to arrange LED elements with a uniform arrangement density without any breaks, and in productivity. However, it was not always possible to ensure the significance of the rigid substrate.

JP 2010-278266 A JP 2012-59867 A

  An object of the present invention is to provide a flexible substrate in which an LED element can be arranged at a position following the truncated cone side surface shape in an LED lighting device or an LED display device having a truncated cone side surface shaped light emitting surface. .

  As a result of intensive studies, the present inventors have found that the above problems can be solved by configuring the flexible substrate with a resin substrate made of a resin film having a fan-shaped outer shape and flexibility. It came to be completed. Specifically, the present invention provides the following.

  (1) A fan-shaped outer shape comprising a resin substrate and a metal wiring portion formed on one surface of the resin substrate, wherein the resin substrate is flexible and has a truncated cone side surface developed. A flexible substrate made of a resin film having

  (2) A frustoconical circuit board formed by joining a pair of linear edges of the flexible board according to (1).

  (3) A frustoconical circuit board in which the flexible board according to (1) is attached to the side surface of the mounting base portion which is a truncated cone-shaped block body or hollow body.

  (4) A frustoconical LED light source in which an LED element is mounted on the circuit board according to (2) or (3).

  (5) An LED illumination device using the LED light source according to (4).

  ADVANTAGE OF THE INVENTION According to this invention, the flexible substrate which can arrange | position an LED element in the position which follows the said truncated cone side surface shape in the LED illuminating device or LED display apparatus which has a light emitting surface of a truncated cone side shape can be provided. . Thereby, in a lighting device having a light emitting surface having the above-described shape, a preferable lighting effect or display quality by uniform light emission from the entire light emitting surface can be obtained.

It is a perspective view of a truncated cone-shaped LED light source. It is a top view of the flexible substrate which can comprise a truncated-cone-shaped circuit board. It is a partial expanded sectional view which shows typically the layer structure of the LED light source of the truncated cone shape of FIG.

  Hereinafter, a flexible substrate of the present invention, a truncated cone-shaped circuit board using the flexible substrate, a truncated cone-shaped LED light source in which an LED element is mounted on the truncated cone-shaped circuit board, and the Embodiments of an LED illumination device and an LED display device using a truncated-cone-shaped LED light source will be sequentially described. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

<Flexible substrate>
As shown in FIGS. 2 and 3, the flexible substrate 1 is a circuit substrate in which a metal wiring part 13 is formed on the surface of a flexible resin substrate 11 having a fan-shaped outer shape. This flexible substrate 1 can be preferably used as a circuit substrate for an LED element.

  The above-mentioned “fan-shaped outer shape” relating to the flexible substrate 1 refers to the shape of a plane figure formed by developing the side surface of the truncated conical circuit substrate 1A as shown in FIG. Specifically, the shape of the outer edge of the resin substrate 11 shown in FIG. 2 is a shape that can be given as a typical example. In the present specification, the “fan-shaped outer shape formed by developing the side surface of the truncated cone” as a whole is sufficient if the outer diameter is fan-shaped or substantially fan-shaped as described above. As long as the effect of the present invention is not particularly obstructed, even if a cutout or a cut is formed in a part of the outer periphery, it is included in the “fan-shaped outer shape formed by developing the side surface of the truncated cone”.

As shown in FIG. 2, the resin substrate 11 includes a pair of arc-shaped edge portions R ₁ and R ₂ along a pair of fan-shaped arc portions having the same center and the same central angle and different diameters, and an arc-shaped edge portion. An outer shape is formed by a pair of linear edge portions L ₁ and L ₂ that connect both end sides of R ₁ and R ₂ in a straight line.

  There is no particular limitation on the size of the flexible substrate 1. Since the flexible substrate 1 has a high degree of design freedom, for example, it can be a large circuit substrate in which the length of R1 is 60 inches or more. Such a large-sized flexible substrate can configure a light source of a huge LED display device installed outdoors, for example, much more easily than a conventional LED element substrate.

  As shown in FIGS. 2 and 3, the flexible substrate 1 has a conductive metal wiring portion 13 made of metal foil on the surface of a resin substrate 11 made of a flexible resin film with an adhesive layer 12 interposed therebetween. Is formed. The metal wiring part 13 is formed on the resin substrate 11 in such a manner that the LED element 2 mounted in a desired arrangement, such as a matrix shape, can be conducted. The resin film in this specification includes not only a film-like material but also a sheet-like material as long as the resin film is flexible enough to form a frustoconical circuit board. To do.

  Further, as shown in FIG. 3, the flexible substrate 1 preferably has an insulating protective film 15 made of thermosetting ink or the like formed on the resin substrate 11 and the metal wiring portion 13. In order to improve the migration resistance of the flexible substrate 1, the insulating protective film 15 is formed on the entire surface of the metal wiring portion 13 except the connection portion for mounting the LED element 2 and on the surface of the resin substrate 11. Of these, it is preferable that the metal wiring portion 13 is formed so as to cover almost the entire surface of the non-formed portion.

  Further, as shown in FIG. 3, the flexible substrate 1 includes an optical protective film 16 such as a reflective layer for improving light utilization efficiency or a black layer for improving display contrast. 15 is preferably further laminated on top of 15. However, by providing the insulating protective film 15 with these optical functions, a necessary optical function can be secured by the insulating protective film 15 without installing an optical film layer.

[Resin substrate]
Although the material of the resin film which comprises the resin substrate 11 is not specifically limited, It is preferable that it is a thermoplastic resin. The resin substrate 11 is required to have high heat resistance and insulation. Preferable examples of such material resins include polyimide (PI), polyethylene naphthalate (PEN), amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, fluororesin, A liquid crystal polymer etc. can be mentioned. Among these, polyethylene naphthalate (PEN) whose heat resistance and dimensional stability are improved by performing a heat resistance improvement treatment such as an annealing treatment can be particularly preferably used. In addition, polyethylene terephthalate (PET) whose flame retardancy is improved by addition of a flame retardant inorganic filler or the like can also be selected as a material resin for the resin base.

  As the resin for forming the resin substrate 11, a resin having a thermal shrinkage start temperature of 100 ° C. or higher, or a resin having improved heat resistance so that the temperature becomes 100 ° C. or higher by the above-described annealing treatment or the like is used. preferable. Usually, the peripheral portion of the element may reach a temperature of about 90 ° C. due to heat generated from the LED element. From this viewpoint, it is preferable that the thermoplastic resin forming the resin substrate has a heat resistance equal to or higher than the above temperature. In this specification, “thermal shrinkage start temperature” means that a sample film made of a thermoplastic resin to be measured is set in a TMA apparatus, a load of 1 g is applied, and the temperature is increased to 120 ° C. at a rate of temperature increase of 2 ° C./min. Measure the amount of shrinkage (in%) at that time, output this data and record the temperature and amount of shrinkage, read the temperature that deviates from the 0% baseline due to shrinkage, and heat shrink the temperature This is the starting temperature. In addition, the “thermosetting temperature” in the present specification is the measurement and calculation of the temperature at the rising position of the thermosetting reaction when the thermosetting resin to be measured is heated, and that temperature is the thermosetting temperature. .

Further, the resin substrate 11 is required to have high insulating properties. In general, the resin substrate 11 preferably has a volume resistivity of 10 ¹⁴ Ω · cm or more, and more preferably 10 ¹⁸ Ω · cm or more.

  The thickness of the resin substrate 11 is not particularly limited, but is approximately 10 μm or more and 500 μm or less, preferably 50 μm or more and 250 μm or less from the viewpoint of having heat resistance and insulating properties and a balance of manufacturing costs. Preferably there is. Also, the thickness is preferably within the above-mentioned thickness range from the viewpoint of maintaining good productivity when manufacturing by the roll-to-roll method.

[Adhesive layer]
As shown in FIG. 3, the formation of the metal wiring portion 13 on the surface of the flexible substrate 1 is preferably performed by a dry laminating method with an adhesive layer 12 interposed. As the adhesive forming the adhesive layer 12, a known resin adhesive can be used as appropriate. Of these resin adhesives, urethane-based, polycarbonate-based, or epoxy-based adhesives can be particularly preferably used.

[Metal wiring section]
The metal wiring portion 13 is a wiring pattern formed on a conductive substrate such as a metal foil on at least one surface of the resin substrate 11 in the flexible substrate 1. The arrangement of the metal wiring portion 13 is not limited to a specific arrangement in both the horizontal direction and the vertical direction as long as the LED elements 2 can be mounted in a matrix at a desired pitch.

  Examples of the metal used as the material of the metal wiring part 13 include metal foils such as aluminum, gold, silver, and copper. The thickness of the metal wiring portion 13 may be set as appropriate according to the magnitude of the withstand current required for the flexible substrate 1 and is not particularly limited, but examples include a thickness of 10 μm to 50 μm. If the metal layer thickness is less than the above lower limit value, the influence of thermal shrinkage of the substrate is large, and the warp after the treatment is likely to increase during the solder reflow process. preferable. On the other hand, when the thickness is 50 μm or less, preferable flexibility of the flexible substrate 1 can be maintained, and a reduction in handling property due to an increase in weight can be prevented.

[Solder layer]
In the flexible substrate 1, when the metal wiring portion 13 and the LED element 2 are bonded, bonding is performed via the solder layer 14. Details of the soldering method will be described later, but can be roughly classified into either a reflow method or a laser method.

[Insulation protective film]
As described above, the insulating protective film 15 is mainly formed on the other portion of the flexible substrate 1 except for a portion that requires electrical bonding on the surface of the metal wiring portion 13 and the resin substrate 11 with thermosetting ink. It is formed to improve the migration resistance.

  As the thermosetting ink, a known ink can be suitably used as long as the thermosetting temperature is about 100 ° C. or less. Specifically, as a representative example of an ink that can preferably use an insulating ink having a polyester resin, an epoxy resin, an epoxy resin and a phenol resin, an epoxy acrylate resin, a silicone resin, or the like as a base resin, respectively. Can be mentioned. Of these, polyester-based thermosetting insulating ink is particularly preferable as a material for forming the insulating protective film 15 of the flexible substrate 1 because of its excellent flexibility. The insulating protective film 15 can be formed with an insulating thermosetting ink by a known method such as screen printing.

[Optical film layer]
The optical film layer 16 is laminated as a member for improving the optical characteristics of the LED device using the flexible substrate 1. The optical film layer 16 may be a reflective film that exhibits reflective performance for improving the illumination effect, or may be a black or dark film that contributes to improving the contrast in order to improve the display effect. Hereinafter, a case where the optical film layer 16 is a reflective film will be mainly described.

  The optical film layer 16 is laminated on the outermost surface on the light emitting surface side of the flexible substrate 1 so as to cover the region excluding the LED element mounting region for the purpose of improving the optical characteristics of the frustoconical LED light source 10. The optical film layer 16 is formed with an opening that can be adapted to the mounting pitch of the LED elements 2 and the shape and size of the mounting region by punching or the like.

  When the optical film layer 16 is a reflective film, as the material, for example, white polyester foam type white polyester, white polyethylene resin, silver vapor-deposited polyester, or the like is appropriately used depending on the use of the final product and its required specifications. be able to.

<Manufacturing flexible substrates>
About the manufacturing method of the flexible substrate 1, it can be based on the manufacturing method of a conventionally well-known electronic substrate. For example, it can be manufactured by a conventional method in which each metal wiring portion is formed on each surface of a resin substrate by an etching process involving chemical treatment.

<Circuit-shaped circuit board>
By joining the pair of linear edge portions L ₁ and L ₂ of the flexible substrate 1, as shown in FIG. 1, a truncated conical circuit substrate 1 A can be obtained. The circuit board 1 </ b> A can be formed by attaching the flexible board 1 along the side surface of the truncated cone-shaped mounting base, in addition to the above-described joining. Arc-like rim portion R ₁ diameter of the flexible substrate 1 is long arc portion becomes the upper edge of the circuit board 1A, the arc-like rim portion R ₂ diameter is shorter arc portion is the lower edge of the circuit board 1A Part.

  The above “conical truncated conical mount” is a truncated conical block or hollow body having no flexibility, and the flexible substrate 1 is attached along the side surface thereof. As long as the surface shape of the circuit board 1 </ b> A made of the flexible substrate 1 can be held in a desired and preferred truncated cone shape. As a material for the mounting base, a hard resin having a predetermined level of insulation or heat resistance, ceramic, or the like can be used as appropriate. In addition, a metal pedestal portion can be used as long as it has a structure that can ensure the insulation required at the connection portion with the flexible substrate 1.

  The circuit board 1 </ b> A becomes a truncated cone-shaped LED light source 10 by mounting the LED element 2. The LED light source 10 is disposed in these devices as a light source of an LED lighting device having a light-emitting surface having a truncated cone shape or a huge LED dot matrix display device having a similar display surface, such as a ceiling light.

  The flexible substrate 1 is, for example, a multilayer circuit board in which metal wiring portions are formed on both surfaces of the resin substrate 11 and are electrically connected through through holes penetrating the resin substrate 11. May be. By adopting such a multilayer structure, the circuit board 1A of the present invention can be preferably used also in the LED dot matrix display device described above.

<Cone-conical LED light source>
The LED light source 10 having a truncated cone shape can be obtained by mounting the LED element 2 on the flexible substrate 1 or the metal wiring portion 13 of the circuit substrate 1A.

  The LED element 2 is a light emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. There are proposed a structure in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element and a structure in which both the P-type and N-type electrodes are provided on one side of the element. Any structure of the LED element 2 can be used in the truncated cone-shaped LED light source 10 of the present invention. Of the above, the LED element having a structure in which both the P-type and N-type electrodes are provided on one side of the element is particularly preferable. It can be preferably used.

<Manufacturing method of frustoconical LED light source>
A method for manufacturing the frustoconical LED light source 10 will be described. The LED element 2 can be mounted either before the flexible substrate 1 is processed into the frustoconical circuit board 1A or after the flexible substrate 1 is processed into the frustoconical circuit board 1A. Is preferably performed before processing into a frustoconical circuit board 1A. The LED element 2 is preferably bonded to the metal wiring portion 13 by soldering. This solder bonding can be performed by a reflow method or a laser method.

<Cone-conical LED lighting device and LED display device>
The frustoconical LED light source 10 can be used as a backlight of a liquid crystal large LED display device having a structure for transmitting information in all 360 ° directions in the horizontal direction. Further, it can be used as a light source of a light emitting display surface in a dot matrix display device having a similar structure.

  By disposing the truncated conical LED light source 10 according to the present invention as the light source of the LED illumination device circle or the LED display device having a smooth curved light emitting surface along the side surface of the truncated cone shape, The preferable display quality guaranteed by the uniformity of the light emitting state can be easily held at a higher level than when a rigid substrate or a flexible substrate premised on a divided arrangement is used. This is because according to the LED light source 10, a large number of LED elements 2 can be arranged in a manner that accurately follows the light emitting surface formed of the curved surface as described above. According to such an arrangement of the LED elements 2, the direction of any light emitted from the individual LED elements 2 is unified in a direction perpendicular to the contact surface at each position of the light emitting surface, and therefore, It is possible to realize a light emission mode in which the light emission direction from the LED element 2 smoothly changes with a continuous and uniform difference along the light emission surface. According to such a light-emitting state, light unevenness that adversely affects visibility is very unlikely to occur. Can be displayed.

1 Flexible substrate 1A Circuit board 1A
DESCRIPTION OF SYMBOLS 11 Resin board | substrate 12 Adhesive bond layer 13 Metal wiring part 14 Solder layer 15 Insulating protective film 16 Optical film layer 2 LED element 10 LED light source

Claims (5)

A resin substrate, and a metal wiring part formed on one surface of the resin substrate,
The said resin substrate is a flexible substrate which consists of a resin film which has flexibility and has the fan-shaped external shape which expand | deploys the truncated cone side surface.   A frustoconical circuit board formed by joining a pair of linear edges of the flexible board according to claim 1.   A circuit board having a truncated cone shape, wherein the flexible substrate according to claim 1 is attached to a side surface of a mounting base portion that is a truncated cone shaped block body or a hollow body.   A frustoconical LED light source comprising an LED element mounted on the circuit board according to claim 2.   A frustoconical LED illumination device using the LED light source according to claim 4.

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