JP2018147969A - Flexible substrate, and led edge light using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible substrate which has a satisfactory light reflecting performance, and which is particularly suitable for a folding/bending process in fabrication of an edge light.SOLUTION: A flexible substrate 1 comprises: a flexible resin substrate 13; a metal wiring part 12 laminated on the resin substrate 13; and an insulative protection film 11 formed in a region on the resin substrate 13 and the metal wiring part 12, excluding a partial region for mounting a light-emitting element. The insulative protection film 11 is formed from a resin composition comprising a silicone resin having an acyclic dimethylsiloxy repeating unit as a primary component, and an inorganic filler containing a titanium oxide. The insulative protection film has a thickness of 15 μm or more and 30 μm or less. The flexible substrate is 10B or more and B or less in pencil hardness according to a pencil hardness test compliant with JIS-K5600-5-4.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a flexible substrate and an LED edge light using the same. The “LED edge light” in this specification refers to all edge light type backlights that use light emitting diode (LED) elements as light sources.

  In recent years, instead of cathode-ray tube type monitors, various LED display devices such as liquid crystal televisions using LED elements as backlight light sources can be used to meet demands for lower power consumption, larger equipment, and thinner devices. Dissemination is progressing rapidly.

  For example, in a liquid crystal television using an LED element as a light source, the LED element is linearly mounted on the substrate as a light source that illuminates the side surface of the liquid crystal panel or the back surface of the liquid crystal panel, that is, the edge. LED edge lights (see Patent Documents 1 and 2) are used.

  In such an edge light type liquid crystal television, the LED edge light is an LED edge light 100 shown in FIG. 1, that is, a flexible substrate 1 on which the LED element 2 is mounted in a block shape having a panel shape or a substantially rectangular parallelepiped shape. In general, it is used in a form fixed to a certain heat conductive substrate 3. In this case, the flexible substrate 1 is used by being bent at an arbitrary angle so that it can follow each corner of the heat conducting substrate 3 without any gap.

  Here, in the above flexible substrate, an insulating protective film is usually formed on the metal wiring part mainly for the purpose of improving the migration resistance (see Patent Document 3).

  And in LED edge light using this flexible substrate, in order to improve the display quality of the display apparatus using the same, it is strongly required to improve the luminance of the LED edge light which is a light source. Therefore, the insulating protective film arranged around the LED element is also made to exhibit a function as a white light reflecting film by adding an inorganic filler powder or the like. For example, by forming an insulating protective film with a composition containing a white inorganic filler in a silicone-based resin having excellent insulating properties and heat resistance, an insulating protective film having excellent light reflection performance is provided. A flexible substrate has been proposed (see Patent Document 4).

  However, in a flexible substrate that is bent along a right angle or a corner portion close to it, there is a problem in that cracks caused by the bending are occasionally found in the white insulating protective film.

  For example, as an example of the prior art intended to improve the bending workability of a flexible substrate, the relationship between the elastic modulus of the metal foil and the resin substrate constituting the flexible substrate and the adhesive layer interposed therebetween is specified. Thus, a metal foil composite with improved bending workability is disclosed (Patent Document 5). However, “folding workability” here refers to the durability of the entire substrate against repeated bending, and with respect to multiple bendings, an adhesive is applied to the resin substrate. The evaluation criterion is that no cracks occur in the laminated metal foil. As for the means for avoiding the crack of the insulating protective film as described above, no solution is shown.

  As a means to prevent cracking of the insulating protective film caused by bending in a flexible substrate that is assumed to be used, only the bent part of the insulating protective film is made of a material softer than the other parts. (Patent Document 6) has been proposed. However, this board has lost the flexibility of the installation mode at the time of use, which is a merit of the flexible board, because the bent part is specified in advance, and the type of insulating protective film material and insulation This is undesirable in that the productivity decreases due to an increase in the number of steps for forming the protective protective film.

  As another means for preventing cracking of the insulating protective film in the flexible substrate as described above, there has also been proposed a flexible substrate in which the insulating protective film is composed of a plurality of layers having different hardnesses (Patent Document 7). In this flexible substrate, a protective layer made of a relatively soft material is formed in the innermost layer, while a protective layer made of a relatively hard material is formed in the outermost layer of the insulating protective film. However, this flexible substrate is assumed to be bent under severe processing conditions with “squaring” to follow the corners of heat-conductive substrates and the like completely without any gap, which is assumed when using an edge light source. However, the main focus is on improving the scratch resistance of the surface by increasing the hardness of the surface of the protective film while ensuring the minimum flexibility. Further, like the flexible substrate of Patent Document 6, it is not preferable in that the productivity is lowered due to an increase in the type of protective film material and the number of protective film forming steps.

International Publication No. 2006/027883 JP 2013-84342 A Japanese Patent Laid-Open No. 2006-15383 Japanese Patent Laid-Open No. 2006-65230 International Publication No. 2012/132814 Japanese Utility Model Publication No. 5-38806 JP 2011-249376 A

  The present invention has been made in view of the above situation. In other words, it is a flexible substrate for LED edge lights that uses a silicone-based resin having excellent insulating properties and heat resistance, and has an insulating protective film imparted with light reflection performance. It aims at providing the flexible substrate for LED edge light suitable for a bending process.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have changed the insulating protective film constituting the flexible substrate into a silicone resin mainly composed of an acyclic dimethylsiloxy repeating unit and titanium oxide. The resin composition containing the inorganic filler to be contained is molded into a predetermined thickness range. At this time, the pencil hardness of the insulating protective film according to JIS-K5600-5-4 is 10B or more. The inventors have found that the above-mentioned problems can be solved by optimizing the hardness so as to be B or less, and the present invention has been completed. Specifically, the present invention provides the following.

  (1) In a portion excluding a resin substrate having flexibility, a metal wiring portion laminated on the resin substrate, and a partial region for mounting a light emitting element on the resin substrate and the metal wiring portion. A resin composition comprising: a silicone resin mainly composed of acyclic dimethylsiloxy repeating units; and an inorganic filler containing titanium oxide. A flexible substrate made of a material, having a thickness of 15 μm or more and 30 μm or less, and a pencil hardness according to JIS-K5600-5-4 of 10 B or more and B or less.

  According to the invention of (1), the insulating protective film 11 of the flexible substrate 1 is formed of a silicone-based resin having excellent heat resistance and insulating properties, and further, the insulating protective film 11 is used as a light reflecting film. In the case where the function is to be exhibited, the hardness of the insulating protective film 11, specifically, the pencil hardness by a pencil hardness test in accordance with JIS-K5600-5-4 is in the range of 10B or more and B or less. Optimized to be. According to this, the insulating protective film 11 which is excellent in heat resistance and insulation and also has preferable light reflection performance can be further provided with excellent flexibility suitable for use in LED edge lights. Such a flexible substrate 1 improves the productivity of the LED edge light 100 using the flexible substrate 1 and also prevents the insulating protective film 11 from cracking, thereby improving the quality stability and durability of the LED edge light 100. Can contribute.

  (2) The flexible substrate according to (1), wherein the pencil hardness is 10B or more and 6B or less.

  According to the invention of (2), the pencil hardness of the insulating protective film is further limited to a softer range. Thereby, the effect of invention of (1) can be expressed more reliably and stably.

  (3) The flexible substrate according to (1) or (2), wherein the degree of polymerization of the dimethylsiloxy repeating unit in the silicone resin is 800 or more and 1200 or less.

  According to the invention of (3), the polymerization degree of the silicone resin constituting the insulating protective film is limited to a specific range. Thereby, the effect of invention of (1) or (2) can be expressed more reliably and stably. In addition, said each polymerization degree can be confirmed by analyzing the peak value of the specific wavelength before and behind superposition | polymerization by FT-IR-analyzing the insulating protective film of a flexible substrate.

  (4) The adhesive layer is formed on the outer surface opposite to the surface on which the metal wiring portion is laminated, and the total thickness including the adhesive layer is 200 μm or less (1) to (3) The flexible substrate in any one.

  In the invention of (4), when the LED edge light is constituted by the flexible substrate of (1) to (3), the thickness of the pressure-sensitive adhesive layer arranged for closely attaching the flexible substrate to the heat conductive substrate. The total thickness of the flexible substrate, including, was optimized to a specific range. According to this, the suitability for bending of the flexible substrate of (1) to (3) is further improved.

  (5) The flexible substrate according to any one of (1) to (4), wherein the resin substrate is polyethylene naphthalate.

  In the invention of (5), PEN is used as the resin substrate. PEN can be used by increasing the thermal shrinkage starting temperature to 100 ° C. or higher by annealing. Conventionally widely used PI is excellent in heat resistance and mechanical strength, but is inferior in transparency and extremely expensive. PEN has sufficient heat resistance and is superior to PI in transparency. Furthermore, it is much cheaper than PI in terms of economy. Therefore, according to the invention of (5), it is possible to provide a sufficiently high-quality flexible substrate while being much cheaper than the conventional product.

  (6) An LED edge light in which an LED mounting module in which an LED element is mounted on the flexible substrate according to any one of (1) to (5) is laminated on a heat conductive base material, and the flexible substrate Is a LED that is continuously adhered to the arrangement surface of the LED element on the heat conducting substrate and the other surface connected to the arrangement surface by being bent along one or a plurality of bending lines. Edge light.

  According to the invention of (6), by using the LED mounting module 10 in which the LED element 2 is mounted on the flexible board 1 according to any one of (1) to (5), the above-mentioned flexible board is provided. By enjoying each effect, it is possible to obtain an LED edge light that is excellent in productivity at the time of manufacture and in stability and durability of quality after completion.

  (7) The heat conducting substrate is a panel-shaped or rectangular parallelepiped block body having a width in the height direction of the small edge surface of 1 mm or more and 2 mm or less, and the LED element has a shape of the small edge surface in a plan view. The LED edge light according to (6), wherein the LED elements are arranged such that outer edges on the one side side of the LED elements are arranged on a straight line that is equidistant from 0 mm to 1 mm from one side side in the width direction. .

  In the invention of (7), due to the excellent bendability of the flexible substrate described in (1) to (5), it is located at the side edge of the small edge surface of the panel-like heat conductive substrate or at a position very close to it. LED elements can be mounted on a straight line with high accuracy. According to this, the arrangement accuracy of the mounting position of the light guide plate and the LED element when the LED edge light is arranged in the display device is improved. Further, it is possible to prevent a decrease in heat dissipation due to a gap between the flexible substrate and the heat conductive base material.

  (8) An LED display device in which the LED edge light according to (6) or (7) is disposed with the light emitting surface of the LED element facing the light incident surface of the side surface of the light guide plate.

  According to the invention of (8), the stability of the quality of the edge light type LED display device can be achieved by using the LED edge light that can accurately mount the arrangement position and the light emitting direction of the LED element with extremely high accuracy. Can be improved.

  According to the present invention, there is provided a flexible substrate for an LED edge light using an insulating protective film provided with a light-reflecting performance using a silicone-based resin having excellent insulating properties and heat resistance, and producing an edge light. It is an object of the present invention to provide a flexible substrate for LED edge light that is easy to bend at the time and is excellent in durability of the insulating protective film after bending.

It is a perspective view of the LED edge light using the flexible substrate of this invention. It is a side view which shows typically the layer structure of the LED edge light using the flexible substrate of this invention. It is a side view which shows typically the layer structure of the flexible substrate of this invention. It is a partial expanded side view of the LED edge light of this invention which shows typically the layer structure of the flexible substrate in the peripheral part of the mounting part of an LED element, and the tracking aspect to a heat conductive base material.

  Hereinafter, each embodiment of the flexible substrate of the present invention and an LED edge light using the flexible substrate will be described. Since the LED edge light can be used particularly preferably as a backlight for a liquid crystal television, the LED edge light of the present invention will be mainly used in the case of using it as a backlight for a liquid crystal television below. Embodiments will be described. However, the scope of the present invention is not limited to the following embodiments. For example, the use of the LED edge light of the present invention as an LED illumination member is naturally within the scope of the present invention as long as the LED edge light satisfies the constituent requirements of the present invention.

<Flexible substrate>
The flexible substrate 1 of the present invention shown in FIGS. 1 to 4 has an edge as shown in FIGS. 1 and 2 by optimizing the material, thickness, and hardness of the insulating protective film in a unique range. Workability when constructing a light-type LED backlight (LED edge light) 100, in particular, “corner foldability” is improved, and cracks in the insulating protective film during or after corner folding Generation can be prevented. The flexible substrate 1 is a printed circuit board that is extremely suitable as a substrate constituting an LED edge light. The LED edge light 100 formed by laminating the LED mounting module 10 on which the LED element is mounted on the heat conductive base material 3 that is a panel-like block body is a liquid crystal television that is required to have both a large screen and a reduced thickness. It can be used very preferably as a backlight.

  In the flexible substrate 1, the metal wiring part 12 is laminated on the surface of the resin substrate 13 having flexibility via an adhesive layer 16. An insulating protective film 11 is formed on the resin substrate 13 and the metal wiring portion 12. On the insulating protective film 11, a reflection sheet made of a white resin or the like having a higher light reflectance is disposed as necessary.

  The flexible substrate 1 is a wiring substrate in which a metal wiring portion 12 is laminated on one surface of a resin substrate 13 via an adhesive layer 16, and an insulating protective film 11 is formed on the surface of the metal wiring portion 12. It is. More specifically, the insulating protective film 11 is substantially the entire surface excluding the portion of the surface of the metal wiring portion 12 that is supposed to be a connection portion with the LED element 2 and the metal wiring of the surface of the resin substrate 13. It is formed so as to cover almost the entire surface of the non-laminated portion of the portion 12.

  The flexible substrate 1 can be bent in such a manner that the hardness of the insulating protective film 11 is optimized within a unique range so as to follow the shape of a corner portion having a right angle or an angle close thereto without a gap. It is said to be “excellent”. Therefore, as shown in FIG.1 and FIG.2, it continues to the surface of the heat conductive base material 3 which is a rectangular parallelepiped-shaped or panel-shaped block body, a fore-edge surface, and a back surface by being bent along several bending lines. Thus, it can be particularly preferably used as a wiring board constituting the LED edge light 100 by being stacked in close contact with each other.

  A metal foil layer 14 is preferably laminated via an adhesive layer 16 on the other surface of the resin substrate 13, that is, the surface opposite to the surface where the metal wiring portion 12 is laminated. Further, it is preferable that an adhesive layer 15 is further formed on the surface of the metal foil layer 14. In the flexible substrate 1 of the present invention, the metal foil layer 14 and the adhesive layer 15 are not necessarily essential constituent elements. In particular, the metal foil layer 14 is provided with a “corner folding suitability”. "Is further improved, it is preferable to include this when used as a wiring board constituting the LED edge light 100. The flexible substrate 1 will be described as an embodiment including the metal foil layer 14. In addition, arrangement | positioning of the metal foil layer 14 can also contribute to the heat dissipation of the LED display apparatus which uses the LED edge light 100.

  A state in which the flexible substrate 1 is folded at a necessary portion and is continuously in close contact with the front surface, the facet surface, and the back surface of the heat conductive base 3 to form the LED edge light 100 as shown in FIG. In other words, the total thickness of the portion from the surface of the insulating protective film 11 to the surface of the metal foil layer 14 is preferably 130 μm or less. If the thickness from the surface of the insulating protective film 11 to the surface of the metal foil layer 14 is 130 μm or less, the flexible substrate 1 for LED edge light can be easily folded at a right angle or along a corner portion close thereto. Can be granted.

  In addition, the flexible substrate 1 is laminated in such a manner that the flexible substrate 1 is continuously adhered to the front surface, the facet surface, and the back surface of the heat conductive base material 3 as shown in FIG. The bending strength by definition is preferably 0.1 or less. By having the metal foil layer 14, while ensuring the properties that can be folded, the layer structure is such that the bending strength of all the layers is 0.1 or less, so that the bending of the corners when bending is performed. Ease is guaranteed. In this specification, “bending strength” means that a strip of 20 mm × 200 mm is produced in an environment of 25 ° C., 100 mm is fixed horizontally from the end of the long side, and the remaining 100 mm is naturally hung vertically. It shall be defined by the reciprocal of the drooping length.

  There is no particular limitation on the planar size of the flexible substrate 1. Utilizing the high degree of freedom of design due to the flexibility of the resin substrate, LED edge lights of various sizes can be easily formed. For example, an LED edge light used for a large-screen liquid crystal television having a screen size of about 55 inches, and an LED edge light in which about 160 LED elements are linearly arranged in a width of about 1220 mm, It can be preferably used.

[Resin substrate]
As the resin substrate 13, a resin film obtained by melt-molding a thermoplastic resin having a thermal shrinkage start temperature of 100 ° C. or higher can be used. As such a thermoplastic resin, for example, various polyester resins whose heat resistance and dimensional stability are improved by performing heat resistance improvement treatment such as annealing treatment can be preferably used. Specifically, polyethylene naphthalate (PEN) or the like imparted with sufficient heat resistance and dimensional stability by annealing treatment. Further, PET or the like whose flame retardancy is improved by adding a flame retardant inorganic filler or the like can be selected as a material resin for the substrate film.

  Here, “thermal shrinkage start temperature” in this specification refers to setting a sample sheet made of a thermoplastic resin to be measured in a TMA apparatus, applying a load of 1 g, and increasing the temperature to 120 ° C. at a rate of temperature increase of 2 ° C./min When the temperature rises, the amount of shrinkage (in%) at that time is measured, and the graph that records the temperature and the amount of shrinkage is output from this data. This is the shrinkage start 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. . In addition, as long as a sheet form is a concept including a film form and both are flexible things, there is no difference in both in this invention.

  The thermoplastic resin used as the material of the resin substrate 13 is required to have a certain level of insulation in addition to heat resistance. Also from this viewpoint, as the material resin of the resin substrate 13, various polyester resins whose heat resistance and dimensional stability are improved by performing a heat resistance improving process such as an annealing process are preferable.

  The thickness of the resin substrate 13 should just be 10 micrometers or more and 25 micrometers or less, and it is preferable that they are 12 micrometers or more and 15 micrometers or less. From the viewpoint of ensuring the heat resistance and insulation required for the flexible substrate 1 and from the viewpoint of maintaining good productivity when manufacturing by the roll-to-roll method, it is at least 10 μm or more. In order to prevent the resin substrate 13 made of a thermoplastic resin from interfering with the squaring and holding of the shape after the squaring, the thickness of the resin substrate 13 is larger than the thickness of the metal foil layer 14. Is relatively small and preferably has a thickness of 25 μm or less.

The insulating property of the resin substrate 13 is, for example, a resin having a volume resistivity that can provide the insulating property required for the flexible substrate 1 when integrated as an edge light type LED backlight in a liquid crystal television. Is required. Generally, the volume resistivity of the resin substrate 13 is preferably 10 ¹⁴ Ω · cm or more, and more preferably 10 ¹⁸ Ω · cm or more.

[Metal wiring section]
The metal wiring portion 12 is a wiring pattern formed of a conductive base material and stacked on one surface of the flexible substrate 1. The metal wiring part 12 in the present invention has a function of supplying electricity by causing a necessary current to flow between the plurality of LED elements 2 arranged in a single-wire or double-wire straight line.

  As shown in FIG. 3, in the flexible substrate 1, a conductive metal wiring portion 12 is laminated on one surface of a resin substrate 13 made of a resin film via an adhesive layer 16. The metal wiring portion 12 is arranged in a single-wire straight line or a double-wire straight line as shown in FIG. 1 and supplies electricity supplied from an external power source to the plurality of LED elements 2 mounted on the flexible substrate 1. It can be configured.

The metal constituting the metal wiring portion 12 has a thermal conductivity λ of 300 W / (m · K) or more and 500 W / (m · K) or less, and an electric resistivity R of the metal constituting the metal wiring portion is 2. 50 × 10 ⁻⁸ Ωm or less is preferable. Here, the measurement of the thermal conductivity λ can use, for example, a thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Industry Co., Ltd., and the measurement of the electrical resistivity R can be performed, for example, a 6517B type electrometer manufactured by Keithley. Can be used. According to this, in the case of copper, for example, the thermal conductivity λ is 403 W / (m · K), and the electrical resistivity R is 1.55 × 10 ⁻⁸ Ωm. By setting the thermal conductivity λ and the electrical resistivity R within the above ranges, it is possible to achieve both heat dissipation and electrical conductivity of the metal wiring part 12 itself. More specifically, since the heat dissipation from the LED element is stabilized and an increase in electrical resistance can be prevented, the variation in light emission between the LED elements 2 is reduced, and the LED element can emit light stably. The lifespan is extended. Further, since deterioration of peripheral members such as the resin substrate 13 due to heat can be prevented, the product life of the LED display device in which the flexible substrate 1 is incorporated as a substrate of the LED edge light can be extended.

  Examples of the metal that satisfies the above range include gold, silver, copper, and the like. The thickness of the metal wiring part 12 should just be 7 micrometers or more and 20 micrometers or less in thickness. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 12 may be 7 μm or more, and is preferably 10 μm or more. Further, if the thickness of the metal layer is less than the above lower limit value, the influence of the heat shrinkage of the resin substrate 13 is large, and the warp after the processing is likely to increase during the solder reflow processing. Is preferably 10 μm or more. On the other hand, when the thickness is 20 μm or less, sufficient flexibility of the flexible substrate 1 can be maintained, and the ease of processing at the time of corner folding along a right angle or a corner close thereto can be maintained. In addition, it is possible to prevent a decrease in handling properties due to an increase in weight.

  Moreover, the metal wiring part 12 is an electrolytic copper foil, and the surface roughness Rz on the side of the laminated surface with the resin substrate 13 is preferably 1.0 or more and 10.0 or less. Here, Rz is a ten-point average roughness defined by JISB0601. From the viewpoint of heat dissipation, by setting the surface roughness within the above range, the surface area on the side of the laminated surface with the resin substrate 13 can be increased, and the heat dissipation can be further enhanced. Moreover, since the adhesiveness with the resin substrate 13 can be improved by the surface unevenness, the heat dissipation can also be improved by this. In this way, the surface physical properties on the rough surface side (mat surface side) of the electrolytic copper foil having the surface roughness Rz can be effectively utilized.

  Moreover, the metal wiring part 12 has a terminal for making an electrical connection between the LED mounting module 10 and the external power source 4 at the end part thereof. Since the flexible substrate 1 is made of a resin film that has a high degree of freedom in design and is easy to process, the degree of freedom in the design of the metal wiring portion is extremely high. According to the LED equipment after mounting the LED element, it is also possible to easily form a wiring that optimally combines the two.

  The metal wiring part 12 is preferably joined to the surface of the flexible substrate 1 by a dry laminating method with an adhesive layer 16 interposed therebetween. As the adhesive forming the adhesive layer, 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. The thickness of the adhesive layer 16 is preferably 1 μm or more and 15 μm or less, and more preferably 4 μm or more and 10 μm or less.

  The metal wiring part 12 may be formed with a bending auxiliary part (not shown) having a smaller wiring width and wiring thickness than other parts in a region at a predetermined distance from the LED element mounting part. The bending auxiliary portion corresponds to the corner portions 31 and 32 of the heat conducting substrate 3 shown in FIG. 4 when the flexible substrate 1 is bent and continuously adhered to a plurality of connected surfaces of the heat conducting substrate 3. By forming on the portion to be bent, that is, the line that becomes the bending line that follows the shape of these corner portions, the ease of bending of the metal wiring portion 12 on the surface of each corner portion 31, 32 is further improved, and the flexible substrate 1 The shape followability with respect to the heat conductive substrate 3 is further enhanced.

[Metal foil layer]
The metal foil layer 14 is a layer made of metal foil that is laminated on the side opposite to the side where the metal wiring part 12 is laminated in the resin substrate 13, that is, the side opposite to the mounting surface of the LED element 2.

  Aluminum foil or copper foil can be used for the metal foil layer 14. When an aluminum foil is used as the metal foil layer 14, its thickness is set to 40 μm or less. Moreover, when using copper foil, the thickness shall be 20 micrometers or less. However, even when any metal foil is used, the thickness thereof is set to be equal to or greater than the thickness of the resin substrate 13. The aluminum foil may be pure aluminum or an aluminum-based metal foil made of an alloy of aluminum and copper, manganese, silicon, magnesium, zinc, nickel, or the like.

  After adjusting the total thickness of the flexible substrate 1 to a predetermined range, the metal foil layer 14 having such a specific thickness is laminated on the non-mounting surface of the LED element of the resin substrate 13 (the back surface of the resin substrate 13). By doing so, “corner folding suitability” based on the viscosity and malleability of the metal foil layer 14, specifically, cornering for following the shape of a corner having a right angle or an angle close thereto can be easily performed. Characteristics can be imparted to the flexible substrate 1.

  The metal foil layer 14 is preferably laminated on the back surface of the flexible substrate 1 by a dry laminating method with an adhesive layer 16 interposed therebetween. As the adhesive forming the adhesive layer 16, 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. The thickness of the adhesive layer 16 is preferably 1 μm or more and 20 μm or less, more preferably 4 μm or more and 15 μm or less when the dry lamination method is used.

  And in the flexible substrate 1 of this invention, this metal foil layer 14 also exhibits the function as an important heat dissipation path which radiates the heat generated from the LED element 2 to the heat conductive substrate 3 as described above. .

[Adhesive layer]
The flexible substrate 1 is previously formed with an adhesive layer 15 on the outer surface of the metal foil layer 14, which is the surface opposite to the resin substrate 13 side of the metal foil layer 14, so as to be exposed on the outermost surface of the flexible substrate 1. It may be what has been done. The adhesive layer 15 is formed on substantially the entire back surface side of the resin substrate 13, and is preferably formed on the entire surface. The adhesive layer 15 in the present invention has at least an adhesive property that can temporarily fix the flexible substrate 1 to a predetermined position (for example, an arrangement as shown in FIG. 1) in the LED edge light 100. Although what is necessary is just to use, what has higher adhesiveness may be used as needed. The adhesive layer 15 is provided with a release layer (not shown) such as a known release seal that protects the surface of the same layer and is easily peelable during use until it is placed on another member. It is preferable to be laminated.

  The adhesive layer 15 can be formed of a general-purpose double-sided adhesive tape (for example, “No. 5605R” manufactured by Nitto Denko Corporation). By forming the adhesive layer with such a double-sided adhesive tape, the formation of the adhesive layer becomes easier, and the productivity of the flexible substrate 1 is improved.

  The thickness of the adhesive layer 15 may be 30 μm or more and 100 μm or less, and preferably 30 μm or more and 80 μm or less. When the thickness of the adhesive layer 15 is 30 μm or more, sufficient adhesiveness between the heat conducting substrate 3 and the LED mounting module can be ensured. When the thickness of the pressure-sensitive adhesive layer 15 is 100 μm or less, the thermal conductivity from the metal foil layer 14 to the heat conductive substrate 3 is also preferable without hindering the ease of corner folding of the flexible substrate 1. It is possible to contribute to the improvement of the heat dissipation of the flexible substrate 1 by being held in the substrate.

[Insulating protective film]
The insulating protective film 11 is mainly formed of LED in other portions except for a portion where electrical connection on the surface of the metal wiring portion 12 and the resin substrate 13 is required by a specific resin composition described in detail below. It is formed in order to improve the migration resistance of the element substrate.

  The insulating protective film 11 is a thin film layer formed on the resin substrate 13 of the flexible substrate 1 used as the wiring substrate and on the surface of the metal wiring portion 12 except for a portion that requires electrical bonding. . This insulating protective film 11 is a so-called resist film that improves the migration resistance of the flexible substrate 1 by having a sufficient insulating property, and further, the display quality of the LED display device using the LED edge light 100. It is also a light reflecting film provided with light reflectivity that contributes to the improvement of the above.

The insulating protective film 11 can be formed of a resin composition such as insulating ink which is mainly made of a silicone resin and further contains an inorganic filler containing titanium oxide. As a silicone resin used as a main material of a resin composition such as an insulating ink for forming the insulating protective film 11, an acyclic dimethylsiloxy repeating unit [—Si (—CH ₃ ) ₂ —O—] is a main component. A silicone resin can be used. More specifically, preferred examples include a silicone resin containing polydimethylsiloxane having a refractive index of 1.41, and a silicone resin in which the main chains are polydimethylsiloxane and the main chains are three-dimensionally cross-linked. .

  The above silicone resin mainly composed of an acyclic dimethylsiloxy repeating unit includes a hard silicone resin, a soft silicone resin, and a silicone rubber, but the flexible substrate 1 is excellent in flexibility. It is preferable to use silicone rubber.

  The insulating protective film 11 is obtained by three-dimensionally crosslinking and hardening an insulating ink containing the above-described silicone resin and an inorganic filler containing titanium oxide, and the above-described repeating unit Si atoms are oxygen atoms or It has a structure in which it is bonded to the Si atom of the next repeating unit via a crosslinkable functional group and three-dimensionally crosslinked.

  As said silicone resin which forms the insulating protective film 11, the thing whose polymerization degree of a dimethylsiloxy repeating unit is 800 or more and 1200 or less can be used preferably especially. When the degree of polymerization is less than 800, the crosslinking reaction between the resin and the resin proceeds excessively and tends to have a hardness of HB or more. In this case, the insulating property is reduced during bending under severe processing conditions with “squaring”. The protective film is liable to crack. On the other hand, when this polymerization degree exceeds 1200, since there are few crosslinking points with resin and a metal wiring part or a resin base material, and also the shrinkage | contraction at the time of hardening is small, adhesion between the metal wiring part 12 and the resin substrate 13 is sufficient. The strength is insufficient, and the insulating protective film 11 is easily peeled off from each of these surfaces.

  Inorganic fillers to be included in the resin composition forming the insulating protective film 11 include titanium oxide, alumina, barium sulfate, magnesia, aluminum nitride, boron nitride, barium titanate, kaolin, talc, calcium carbonate, It is preferable to include at least one light reflecting agent selected from zinc oxide, silica, mica powder, powdered glass, powdered nickel and powdered aluminum. The content of the inorganic filler in the resin composition forming the insulating protective film is preferably 50 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the silicone resin in the insulating ink, and 100 parts by mass. More preferably, it is 300 parts by mass or less. If the content of the inorganic filler exceeds 400 parts by mass in the above content ratio, the adhesiveness of the insulating protective film 11 to the metal wiring part 12 and the resin substrate 13 is not preferable, and the content ratio is If it is less than 50 parts by mass, it is difficult to maintain sufficient light reflection performance when the film thickness is 50 μm or less.

  The resin composition that forms the insulating protective film preferably contains a crosslinking agent that promotes three-dimensional crosslinking to the silicone resin. Specific examples of such a crosslinking agent include hydrogen organopolysiloxane, platinum group metal catalyst-containing polysiloxane, various peroxides, and the like. These crosslinking agents are preferably contained in a proportion of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the silicone resin.

  The thickness of the insulating protective film 11 is 15 μm or more and 30 μm or less, and preferably 18 μm or more and 25 μm or less. When the thickness is less than 15 μm, the insulation may be insufficient. On the other hand, from the viewpoint of maintaining suitability for bending, the thickness is preferably 30 μm or less.

  The insulating protective film 11 is required to have a light reflectance at a wavelength of 420 nm or more and 780 nm or less of 80% or more, and preferably 90% or more. The flexible substrate 1 has a light reflectance of 80 even when the thickness of the insulating protective film 11 is 50 μm or less by setting the content of the above inorganic filler to 100 parts by mass of the silicone resin to 50 parts by mass or more. % Or more. Further, by setting the content of the inorganic filler to 200 parts by mass or more, the light reflectance can be set to 80% or more even when the thickness of the insulating protective film 11 is 30 μm. In addition, since it is difficult to strictly measure the absolute reflectance, the relative reflectance with the reference standard sample is usually used for the above-described light reflectance. In the present invention, barium sulfate is used as a comparative standard sample. The light reflectance in the present invention is determined by attaching an integrating sphere attachment device (for example, ISR2200 manufactured by Shimadzu Corporation) to a spectrophotometer (for example, Shimadzu Corporation UV2450), using barium sulfate as a standard plate, The relative reflectance measured as 100% is a measured value.

  On the other hand, the insulating protective film 11 maintains the preferable light reflection performance of the insulating protective film 11 as described above by setting the content of the inorganic filler to 100 parts by mass of the silicone resin to 300 parts by mass or less. As it is, the adhesiveness to the metal wiring part 12 and the resin substrate 13 can be maintained in a more preferable state.

  In the flexible substrate 1, the insulating protective film 11 is characterized in that its pencil hardness is adjusted to 10B or more and B or less, preferably 10B or more and 6B or less. The pencil hardness in this specification means the value by the pencil hardness test based on JIS-K5600-5-4. When the pencil hardness of the insulating protective film 11 exceeds B, the insulating protective film is insufficient due to insufficient followability of the flexible flexible substrate 1 to the resin substrate 13 at the time of manufacturing or after the LED edge light 100 is manufactured. For 11, there are many cases in which a crack occurs in a part thereof. In other words, the “square folding processability” of the flexible substrate becomes insufficient. If the pencil hardness is less than 10B, it is difficult to ensure the durability of the insulating protective film 11. The pencil hardness of the insulating protective film can be adjusted to an arbitrary hardness, for example, by adjusting the amount of the crosslinking agent added to the resin composition forming the insulating protective film.

[Method for manufacturing flexible substrate]
The flexible substrate 1 can be manufactured by an etching process which is one of known methods for manufacturing an electronic substrate. Further, depending on the material resin to be selected, it is preferable to subject the resin to a heat resistance improvement treatment by an annealing treatment in advance as necessary.

(Annealing treatment)
For the annealing treatment, a conventionally known heat treatment means can be used. As an example of the annealing treatment temperature, when the thermoplastic resin forming the resin substrate 13 is PEN, the glass transition temperature to the melting point range, more specifically 160 ° C. to 260 ° C., more preferably 180 ° C. to 230 ° C. Range. An example of the annealing time is about 10 seconds to 5 minutes. According to such heat treatment conditions, the thermal contraction start temperature of PEN, which is generally about 80 ° C., can be improved to about 100 ° C.

(Etching process)
On the surface of the resin substrate 13, a metal wiring part 12 such as a copper foil used as a material for the metal wiring part 12 is laminated to obtain a laminated body used as a material for the flexible substrate 1. As a lamination method, a metal foil is adhered to the surface of the resin substrate 13 with an adhesive, or a plating method or a vapor deposition method (sputtering, ion plating, electron beam evaporation, Examples of the method include vapor deposition of the metal wiring portion 12 by vacuum vapor deposition, chemical vapor deposition, or the like. From the viewpoint of cost and productivity, a method of adhering the metal foil to the surface of the resin substrate 13 with a urethane adhesive is advantageous.

  Next, an etching mask patterned in the shape of the metal wiring portion 12 is formed on the surface of the metal foil of the laminate. In the future, the etching mask is provided so that the wiring pattern forming portion of the metal foil to be the metal wiring portion 12 is free from corrosion by the etching solution. The method for forming the etching mask is not particularly limited. For example, the etching mask may be formed on the surface of the laminated sheet by exposing the photoresist or dry film through the photomask and then developing the ink mask. An etching mask may be formed on the surface of the laminated sheet by this printing technique.

  Next, the metal foil in a portion not covered with the etching mask is removed with an immersion liquid. Thereby, parts other than the location used as the metal wiring part 12 are removed among metal foils.

  Finally, the etching mask is removed using an alkaline stripping solution. As a result, the etching mask is removed from the surface of the metal wiring portion 12.

(Insulating protective film formation process)
After laminating the metal wiring part 12, the insulating protective film 11 is formed on the metal wiring part 12. These formations can be performed by known methods. The silicone-based insulating ink used in the present invention can be formed by various methods such as screen printing, bar coater, roll coater, reverse coater, gravure coater, air knife coater, spray coater, or curtain coater.

  Note that screen printing or the like is performed in a plurality of times, so that the film thickness of the insulating protective film 11 can be easily adjusted, and when the insulating protective film 11 composed of a plurality of layers is used, the LED element 2 By relatively increasing the film thickness of only the peripheral part of the mounting area, it is possible to improve the light reflection performance efficiently.

(Adhesive layer forming process)
After the metal wiring portion is laminated, the pressure-sensitive adhesive layer 15 is formed by using a double-sided pressure-sensitive adhesive tape or the like or by curing an adhesive as described above. As described above, it is preferable that a release layer is further disposed on the adhesive layer 15.

<LED mounting module>
The LED mounting module 10 can be obtained by mounting the LED element 2 on the metal wiring part 12 of the flexible substrate 1.

  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 for the LED mounting module 10 of the present invention, and among the above, the LED element having a structure in which both the P-type and N-type electrodes are provided on the element single side is particularly preferably used. Can do.

  The LED mounting module 10 is applied to an LED display device having a screen size of 50 inches or more, preferably 55 inches or more as a corresponding screen size on the premise of mounting LED elements 2 of about 100 to 200 LED elements. It is preferred that Since the flexible substrate of the present invention has a high degree of freedom in circuit design, the number of LED elements 2 to be mounted, the arrangement interval, and the like can be freely adjusted. It is possible to respond flexibly at a lower cost than in the past.

  In the LED mounting module 10, when a resin film having anisotropy in terms of heat shrinkage is used for the resin substrate 13, it is preferable that the LED elements are mounted on a straight line along a direction in which the heat shrinkage is small. . As a specific example, if the thermoplastic resin constituting the resin substrate 13 is biaxially stretched polyethylene naphthalate, the LED elements 2 are arranged on a straight line along the TD direction of the biaxially stretched polyethylene naphthalate. It is preferable. By mounting the LED elements in this way, in the LED edge light 100 in which the LED mounting module 10 is arranged, the position of the LED elements and the metal wiring portion due to relatively large thermal contraction that occurs along the MD direction of the resin substrate 13. The risk of a short circuit between 12 can be reduced.

  The biaxially stretched resin is obtained by subjecting a resin molded into a sheet shape to biaxial stretching. In the biaxial stretching process, the resin is heated to a temperature higher than Tg, stretched in the MD direction by the tension between the rolls of the biaxial stretching apparatus, and simultaneously or after that, the biaxial stretching apparatus Is stretched in the TD direction by a tenter. That is, it is stretched and processed in two directions (MD direction and TD direction) orthogonal to each other. Since this series of operations is performed while heating the resin base material, the molecules contained in the resin base material are aligned (oriented) along the stretching direction and partially crystallized. In this specification, as widely used in the technical field to which the present invention belongs, the length direction in biaxial stretching is indicated as MD (Machine Direction) direction, and in biaxial stretching. The width direction is displayed as a TD (Transverse Direction) direction. Generally, the stretch ratio in the machine length direction (stretch ratio in the MD direction) due to the tension between the rolls is larger than the stretch ratio in the machine width direction (stretch ratio in the TD direction) by the tenter. It becomes. For this reason, in the resin base material subjected to biaxial stretching, a larger internal stress remains in the MD direction due to high stretching than in the TD direction.

  From the above, the MD direction of the biaxially stretched resin is substantially one direction in which the thermal shrinkage rate during heating is larger due to the remaining internal stress larger than in other directions. That is. In the practice of the present invention, the resin having anisotropy as the resin substrate actually has a relatively large internal stress remaining in the other direction regardless of the details of the stretching process at the time of formation. Therefore, one direction in which the heat shrinkage rate during heating is relatively large is regarded as the “MD direction”, and the other direction in which the heat shrinkage rate is relatively small is regarded as the “TD direction”. And

[Method for manufacturing LED mounting module]
A method for manufacturing the LED mounting module 10 using the flexible substrate 1 will be described. Bonding of the LED element 2 to the metal wiring part 12 can be preferably performed by soldering. This solder bonding can be performed by a reflow method or a laser method. In the reflow method, the LED element 2 is mounted on the metal wiring part 12 via solder, and then the flexible substrate 1 is transported into the reflow furnace and hot air at a predetermined temperature is blown to the metal wiring part 12 in the reflow furnace. Thus, the solder paste is melted, and the LED element 2 is soldered to the metal wiring portion 12. The laser method is a method of soldering the LED element 2 to the metal wiring portion 12 by locally heating the solder with a laser.

  When solder joining of the LED element 2 to the metal wiring part 12 is performed by a laser method, it is preferable to adopt a method of performing solder reflow by laser irradiation from the back surface side of the resin substrate 13. Thereby, the ignition of the organic component of the solder by heating and the accompanying damage to the base material can be more reliably suppressed.

<LED edge light>
As shown in FIG. 1 and FIG. 4, in the LED edge light 100, the flexible substrate 1 has one side surface that is a surface on the side where the LED elements in the heat conducting base material 3 are disposed, and the other side connected to the one side surface. The flexible substrate 1 is in close contact with the two surfaces. “Continuously adhering” means adhering substantially over the entire surface with almost no gap. The adhesion is preferably via the pressure-sensitive adhesive layer 15, but may be due to the addition of other pressure-sensitive adhesive or adhesion means.

  The LED edge light 100 is an edge light that is compact and has high heat dissipation performance by making the adhesive layer 15 adhere to the surface of the heat conductive base material 3 without any gap, making use of the excellent “corner foldability” of the flexible substrate 1. It is configured as a system LED backlight.

  As a specific manufacturing method of the LED edge light 100, a method according to the following procedure can be exemplified. First, one end portion of the LED mounting module 10 in which the LED element 2 is mounted on the flexible substrate 1 is first connected to the one surface where the LED element 2 is disposed on the heat conducting substrate 3 on the adhesive layer 15 and, if necessary. While being fixed by other temporary fixing means and applying an appropriate tensile force from the other end portion to this, the corner between the one surface and the LED element 2 arrangement surface and the arrangement surface of the LED element 2 and the other The entire surface of the non-mounting surface of the LED element 2 of the LED mounting module 10 is brought into close contact with the heat conducting base material 3 while the flexible substrate 1 is squared along the corners between the two surfaces. Thereby, the some LED element 2 is arrange | positioned on the one side of the heat conductive base material 3 in the shape of a single line or a double line.

  The heat conductive substrate 3 is a panel made of a material having thermal conductivity or a block body within a desired thickness range, and a small edge surface (side surface in the case of a block body) of the panel is an arrangement region of the LED elements 2. It is the thing of the shape which can comprise. The width in the thickness direction of the heat conductive substrate 3 is preferably 0.5 mm or more and 4 mm or less. Thereby, LED elements having a short side of about 0.1 mm or more and 2 mm or less can be mounted in a straight line, and can contribute to the thinning of the LED display device.

  Specifically, aluminum, iron, or the like can be preferably used as the material for the heat conductive substrate 3. Of these, aluminum is particularly preferred from the viewpoint of thermal conductivity.

  Here, when the heat conductive base material 3 is a panel-like block body, the LED element 2 is connected via the flexible substrate 1 in FIG. The width of the mounting surface) in the height direction, that is, the thickness of the panel-like block body needs to be at least the width of the outer diameter (short side) of the LED element 2. However, nowadays, where the contribution to the thinning of the LED display device is required, it is desirable that the heat conductive substrate 3 is also as thin as possible. In this regard, by using the LED mounting module 10 that can flexibly follow the shape of the heat conductive base material 3, the width in the height direction of the edge surface of the heat conductive base material 3 that becomes the mounting region of the LED element 2 Can be minimized to a size very close to the outer diameter of the LED element 2. For example, assuming the case where the width in the height direction (the thickness of the block body) of the small edge surface of the heat conducting substrate 3 is 0.5 mm or more and 4 mm or less, and the outer diameter of the LED element 2 is 1 mm. For example, in a plan view from the facet side, the one side of the LED element 2 on one side in the width direction of the facet or on a straight line that is equidistant within 1 mm from the same side The LED elements 2 can be mounted such that the outer edges of the LED elements are aligned. Thus, when the LED element 2 can be mounted in a straight line at the side edge of the small edge surface of the heat conducting substrate 3 or at a position very close to it, the accuracy of position adjustment with the light guide plate is increased. preferable.

  The LED edge light 100 is used as an edge light type backlight such that the light emitting surface of the LED element 2 faces a side surface (edge) of a light guide plate in an LED display device such as a liquid crystal television. For example, by forming the resin substrate 13 with a transparent resin and ensuring the transparency of the LED mounting module 10, accurate alignment accuracy and workability when the LED mounting module 10 is placed on the heat conductive base material are improved. Can be improved.

<Manufacturing of Flexible Substrate of Example>
The flexible substrate (sample for a test) of an Example and a comparative example was manufactured as follows.

[Resin substrate and metal wiring part]
A copper foil for forming a metal wiring portion is laminated on one surface of a 10 mm × 100 mm film-shaped resin substrate (polyethylene naphthalate, thermal conductivity 0.2 W / K · m), and the resin substrate A metal foil layer (aluminum foil, but only copper foil in Example 2) is attached to the other surface of the adhesive, and an adhesive (urethane-based adhesive (manufactured by Mitsui Chemicals)) (two-pack type) main agent: Takelac A-1143, Lamination was performed using a curing agent: Takenate A-3). Then, the copper layer for metal wiring was etched and the metal wiring part of the same pattern was comprised in all the Examples and the comparative examples.

[Insulating protective film]
Furthermore, an insulating protective film is formed on each of the film thicknesses described in Table 1 with an insulating ink containing a different silicone resin for each of the examples and comparative examples on the resin substrate and the metal wiring part. It was set as the sample for a test of the flexible substrate of an example and a comparative example. As the silicone resin, the following silicone resins 1 to 3 were used properly as shown in Table 1 for each Example and Comparative Example. Moreover, in addition to each silicone resin, an inorganic filler (titanium oxide powder) with a crosslinking agent (hydrogenorganopolysiloxane) at a ratio (parts by mass) shown in Table 1 with respect to 100 parts by mass of the silicone resin, Similarly, it was contained at a ratio (parts by mass) shown in Table 1 with respect to 100 parts by mass of the silicone resin.
Silicone resin 1: degree of polymerization of dimethylsiloxy repeating unit is 1000
Silicone resin 2: Degree of polymerization of dimethylsiloxy repeating unit is 500
Silicone resin 3: Degree of polymerization of dimethylsiloxy repeating unit is 100
In addition, each said degree of polymerization can be confirmed by analyzing the peak value of the specific wavelength before and behind superposition | polymerization by FT-IR analysis as above-mentioned.

<Evaluation Example 1: Pencil hardness>
The pencil hardness of the surface of the insulating protective film of each flexible substrate in Examples and Comparative Examples was measured and confirmed by a test according to JISK5600-5-4 (1999). The measurement results were as described in Table 1.

<Evaluation Example 2: Suitability for corner folding>
For each of the flexible substrates of the examples and comparative examples, a test for examining corner folding processability was performed.
As long as the side ends of the flexible substrates of Examples and Comparative Examples are fixed to the surface of a 1.5 mm thick aluminum plate (assuming a heat conductive base material), the resin does not stretch on each flexible substrate visually. While applying the pulling force, the flexible plate is squared manually along the corners between the front and side surfaces of the aluminum plate and the corners between the side and back surfaces. However, a test was conducted by performing an operation of sticking this without gaps and investigating the suitability for corner folding. The evaluation criteria were as follows. The evaluation results are shown in Table 1 as “square folding”.
(Evaluation criteria for corner foldability)
A: “A beveled portion (a visible edge portion) covered with an insulating protective film is formed in the bent portion, and the crack that is visible in the insulating protective film including the squared portion is It didn't exist. "
B: “A chamfered portion (a visible edge portion) covered with an insulating protective film is formed in the bent portion, and a visible crack is formed on the surface around the bent portion of the insulating protective film. However, cracks were present only in the surface layer portion of the insulating protective film, and there were no cracks reaching the opposite surface.
C: “There was a crack reaching the surface on the opposite side of the surface around the bent portion of the insulating protective film.”

<Evaluation Example 3: Suppression of substrate deformation (warping)>
For each of the flexible substrates of Examples and Comparative Examples, a test was conducted to examine suppression of substrate deformation (warpage). The measurement method of “warp” was as follows.
The warpage rate was calculated according to JIS C 6471-1995 (Reference 2: Warpage rate and twist rate). Gently place the sample on a horizontal table so that the top is concave, and make sure that no vertical force is applied, so that the vertical gap between the four corners of the sample and the table is 1 mm in a straight line. And measure the maximum value. Next, each of the four sides of the sample is measured to a unit of 1 mm. And the curvature rate (%) was computed by the following formula.
Warpage rate (%) = Maximum value of warpage ÷ (Average length of 4 sides of sample)
The evaluation criteria are as follows. The evaluation results are shown in Table 1 as “warping”.
(Evaluation criteria for “warp”)
A: Warpage rate is 3.0% or less B: Warpage rate is over 3.0% <Evaluation Example 4: Light reflectance>
About each flexible substrate of an Example and a comparative example, light reflectance was measured and evaluated.
The light reflectance is obtained by using barium sulfate as a comparative standard sample, attaching an integrating sphere attachment device (ISR2200 manufactured by Shimadzu Corporation) to a spectrophotometer (Shimadzu Corporation UV2450), and using barium sulfate as a standard plate. The relative reflectance with the standard plate as 100% was measured, and this was used as the value of the light reflectance. In the measurement, the reflectance was measured at three standard wavelengths important in the display performance of the LED display device, that is, 450 nm (B), 550 nm (G), and 650 nm (R). The evaluation criteria for the measurement results are as follows. The evaluation results are shown in Table 1 as “reflectivity”.
(Light reflectance evaluation criteria)
A: “At all the above measurement wavelengths, the light reflectance is 80% or more.”
B: “The light reflectance is 80% or more at any of the measurement points of 450 nm (B), 550 nm (G), and 650 nm (R), but is less than 80% at any of the other measurement points.”
C: “The light reflectance is less than 80% at all measurement points of 450 nm (B), 550 nm (G), and 650 nm (R)”

  From Table 1, it can be seen that the flexible substrate of the present invention is a flexible substrate that has a sufficient light reflection performance and is particularly suitable for bending processing when creating an edge light.

DESCRIPTION OF SYMBOLS 1 Flexible substrate 11 Insulating protective film 12 Metal wiring part 13 Resin substrate 14 Metal foil layer 15 Adhesive layer 16 Adhesive layer 2 LED element 3 Thermal conduction base material 31 and 32 Corner | angular part 10 LED mounting module 100 LED edge light

Claims (8)

A flexible resin substrate;
A metal wiring portion laminated on the resin substrate;
An insulating protective film formed on a portion excluding a partial region for mounting a light emitting element on the resin substrate and the metal wiring portion,
The insulating protective film is made of a resin composition containing a silicone resin mainly composed of an acyclic dimethylsiloxy repeating unit and an inorganic filler containing titanium oxide, and has a thickness of 15 μm or more and 30 μm or less. A flexible substrate having a pencil hardness of 10B or more and B or less by a pencil hardness test according to JIS-K5600-5-4.   The flexible substrate according to claim 1, wherein the pencil hardness is 10B or more and 6B or less.   The flexible substrate according to claim 1 or 2, wherein a degree of polymerization of the dimethylsiloxy repeating unit in the silicone resin is 800 or more and 1200 or less. An adhesive layer is formed on the outer surface opposite to the surface on which the metal wiring portion is laminated,
The flexible substrate according to claim 1, wherein the total thickness including the adhesive layer is 200 μm or less.   The flexible substrate according to claim 1, wherein the resin substrate is polyethylene naphthalate. An LED mounting module in which an LED element is mounted on the flexible substrate according to any one of claims 1 to 5, is an LED edge light that is laminated on a heat conductive base material,
The flexible substrate is bent along one or a plurality of fold lines so as to continuously adhere to the arrangement surface of the LED element in the heat conducting substrate and another surface connected to the arrangement surface. LED edge light. The heat conducting substrate is a panel-shaped or rectangular parallelepiped block body having a width in the height direction of the facet of 1 mm or more and 2 mm or less,
The LED element is arranged so that the outer edge on the one side side of the LED element is aligned on a straight line at an equal distance of 0 mm or more and 1 mm or less from one side side in the width direction of the facet surface in plan view. The LED edge light according to claim 6 arranged.   8. An LED display device, wherein the LED edge light according to claim 6 or 7 is disposed with the light emitting surface of the LED element facing the light incident surface of the side surface of the light guide plate.

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