JP2016197668A - Flexible multilayer circuit board for led element, and led dot matrix display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible multilayer circuit board for an LED element capable of avoiding reduction in perceptibility and designability caused by increase in the number of layers in a circuit configuration, in an LED dot matrix display device, and to provide an LED dot matrix display device using the same.SOLUTION: A flexible multilayer circuit board 1 comprises: a first metal wiring part 121 laminated on one surface of a support substrate 111 via a first adhesive agent layer 131; a second metal wiring part 122 laminated on the other surface of the support substrate 111 via a second adhesive agent layer 132; and a black layer 14 for improving contrast. In the flexible multilayer circuit board 1, at least any one adhesive agent layer, among the adhesive agent layers formed between any layers at an LED element mounting surface side from the second metal wiring part 122, is a black adhesive agent layer whose ΔL* value is equal to or less than 60.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flexible multilayer circuit board for LED elements and an LED dot matrix display device using the same. Note that the “LED dot matrix display device” means that light emitting units formed in the shape of dots formed by mounting LEDs are two-dimensionally arrayed, and these light emitting units are selectively emitted in any combination to obtain a desired A light-emitting display device that displays and displays characters, symbols, or symbols.

  If this LED dot matrix display device is used, it is possible to display a two-dimensional array having a meaningful arrangement such as characters and symbols in the arrangement relation by the combination of light emitting dots that are selected to emit light. In addition, in this LED dot matrix display device, the light emitted from the LED elements is directly recognized as the above two-dimensional array, so that it has higher brightness and higher brightness than the display using liquid crystal or the like. Contrast is easy to achieve. Further, it is advantageous in that high visibility is easily obtained even when ambient light is irradiated on the display surface of the display device. As such an LED dot matrix display device, for example, an LED display panel in which a display window is formed on a housing surface housing electronic components and a plurality of LED elements are arranged in a matrix on a wiring board is provided. There is known an LED display device configured to control display of LED elements of the LED display panel (see Patent Document 1).

  In addition, as described in Patent Document 1 and Patent Document 2, an LED dot matrix display device is usually formed on a light emitting surface side of light emitted from an LED element, in accordance with the arrangement of the LED elements. A contrast enhancing black layer is disposed to block the light leaving a light hole. This black layer for improving contrast improves the substantial luminance of the light emitting body during lighting by blackening the periphery of the LED element that is the light emitting body, and further, the luminance during lighting and during non-lighting It is arranged for the purpose of increasing the difference from the dark luminance and improving the contrast in the screen display of the LED dot matrix display device.

  Moreover, in the LED dot matrix display device, in many cases, the conduction to each element that enables the light emission control of a large number of LED elements is a multilayer circuit board in which metal wiring portions are formed on both sides of the support substrate ( Patent Document 3 and Patent Document 4) are used. Even if a complicated circuit configuration is required due to the multi-layered wiring portion, for example, a multi-color display device that arbitrarily selects each LED in an LED element incorporating three-color LEDs and emits light. LED dots can be reduced by minimizing the area of the LED mounting area occupied by each light emitting unit, and in response to demands for further densification and refinement of the circuit configuration. Improvement of productivity and quality stability of the matrix display device has been realized.

  However, in the LED dot matrix display device having the multilayer circuit configuration as described above, even when the contrast improving black layer is disposed above the light emitting surface side of the LED element, the LED element and the contrast improving black layer It has been extremely difficult to completely prevent a part of the surface of the metal wiring portion on the lower layer side from being exposed in a visible manner from the gap portion between them. The exposure of the metal wiring portion on the lower layer side deteriorates the contrast on the screen display and lowers the visibility. This also reduces the design of the appearance of the device.

JP 2006-145682 A JP 2003-173149 A JP 2001-345485 A JP 2008-218674 A

  The present invention provides a flexible multilayer circuit board for an LED element and an LED dot matrix using the same, which can avoid the above-described deterioration in visibility and design due to the multilayered circuit configuration in an LED dot matrix display device. An object is to provide a display device.

  As a result of intensive studies, the present inventors have made a function as a concealing layer by containing a black or dark pigment on the adhesive layer disposed on the surface of the support substrate that is the mounting surface side of the LED element. By providing the above, it has been found that the above problems can be solved without adding an additional concealing layer, and the present invention has been completed. Specifically, the present invention provides the following.

  (1) A flexible multilayer circuit board for LED elements, a flexible support board, and a first metal wiring portion laminated on one surface of the support board via a first adhesive layer A second metal wiring portion laminated on the other surface of the support substrate via a second adhesive layer, and an LED element mounting region on the outermost layer on the LED element mounting surface side of the flexible multilayer circuit board. A contrast-improving black layer that covers the portion to be removed, and is formed between any of the layers closer to the LED element mounting surface than the second metal wiring portion in the flexible multilayer circuit board. Among the adhesive layers, at least one of the adhesive layers is a black adhesive having a ΔL * value of 60 or less measured according to a D65 light source and a 10 ° viewing angle according to JIS-Z8722. Flexible multi-layer circuit board that is a.

  (2) The flexible multilayer circuit board according to (1), wherein the first adhesive layer is the black adhesive layer.

  (3) The flexible multilayer circuit board according to (1) or (2), wherein the black adhesive forming the black adhesive layer is an infrared transmitting adhesive that transmits near infrared rays having a wavelength of 750 nm to 1500 nm.

  (4) The flexible multilayer circuit according to any one of (1) to (3), wherein the black adhesive is an infrared transmitting adhesive containing a resin component and a pigment component containing an oxazine pigment. substrate.

  (5) The black adhesive contains a resin component and a pigment component comprising a benzimidazolone pigment and a phthalocyanine pigment, and the benzimidazolone pigment and the phthalocyanine pigment in the pigment component The flexible multilayer circuit board according to any one of (1) to (3), which is an infrared transmitting adhesive having a mass ratio of 30:70 to 70:30.

  (6) The contrast improving black layer and the black adhesive layer both have a ΔL * value of 60 or less, measured according to the conditions of a D65 light source and a 10 ° viewing angle in accordance with JIS-Z8722. And the flexible multilayer circuit board in any one of (1) to (5) whose difference of those both values is 20 or less.

  (7) The flexible multilayer circuit board according to any one of (1) to (6), wherein the contrast improving black layer and the black adhesive layer are formed to include the same dark pigment.

  (8) The flexible multilayer circuit board according to any one of (1) to (7), wherein the first metal wiring portion is a copper foil whose surface is blackened.

  (9) The flexible multilayer circuit board according to any one of (1) to (8), wherein a third metal wiring portion is further laminated on the surface of the second metal wiring portion via an insulating protective film.

  (10) An LED dot matrix display device comprising an LED element mounted on the flexible multilayer circuit board according to any one of (1) to (9).

  According to the present invention, in a LED dot matrix display device, a flexible multilayer circuit board for an LED element that can avoid deterioration in visibility and design due to multilayering of circuit configurations, and an LED dot matrix using the same A display device can be provided.

It is a perspective view which shows typically the structure outline of the LED dot matrix display apparatus formed by mounting an LED element on the flexible multilayer circuit board of this invention. It is a fragmentary sectional view which shows typically the layer structure of the LED dot matrix display apparatus in the AA cross section of FIG. It is a top view which shows typically a mode at the time of seeing the peripheral part of the LED element mounting area | region of the LED dot matrix display apparatus of this invention from the upper surface side.

  Hereinafter, each embodiment of a flexible multilayer circuit board for LED elements of the present invention (hereinafter also simply referred to as “flexible multilayer circuit board”) and an LED dot matrix display device in which LED elements are mounted on the flexible multilayer circuit board. Will be described sequentially. 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 multilayer circuit board>
[overall structure]
The flexible multilayer circuit board 1 of the present invention is a flexible wiring board that can constitute the LED dot matrix display device 10 of the present invention by mounting the LED elements 2 as shown in FIG.

  As shown in FIG. 2, the flexible multilayer circuit board 1 has a first metal wiring portion 121 formed on one surface of a support substrate 111 via a first adhesive layer 131. Then, the second surface of the support substrate 111 opposite to the surface on which the first metal wiring part 121 is formed (hereinafter also referred to as “back surface of the support substrate 111”) is interposed through the second adhesive layer 132. Metal wiring portions 122 are stacked. In addition, an insulating layer (not shown) such as a solder resist is usually formed on the surface of the second metal wiring portion 122, and further, if necessary, made of a resin base material, etc. The insulating protective film 112 having the above function is laminated with the adhesive layer 133 interposed therebetween. Also, the flexible multilayer circuit board 1 is formed with a through hole 15 that conducts between the light emitting surface side metal wiring part 121 and the back side metal wiring part 122.

  Here, the “first adhesive layer” in this specification refers to the adhesion of the metal wiring part to the support substrate or the like when the surface of the flexible multilayer circuit board that is the LED element mounting surface is the substrate surface. Therefore, the adhesive layer that is arranged closest to the LED element mounting surface side of the flexible multilayer circuit board among the adhesive layers that are formed for this purpose.

  As shown in FIG. 2, the flexible multilayer circuit board 1 directly on the surface of the support substrate 111 and the surface of the first metal wiring part 121 except for the LED mounting region, or directly A contrast improving black layer 14 is formed through another functional layer. The black layer 14 for improving contrast can be formed of a resin base material containing a black pigment. The “LED element mounting region” in the present specification is a region composed of a portion to be joined to the first metal wiring part 121 of the LED element 2 in the flexible multilayer circuit board 1 and its peripheral portion. It refers to the area immediately below the space required as the optical path to the outside of the light emitted from the LED element when the element 2 is installed. In FIG. 2, a portion where the contrast improving black layer 14 is not formed on the surface of the first metal wiring portion 121 is an LED element mounting region.

  Here, in the conventional general multilayer circuit board whose basic configuration is the same as that of the flexible multilayer circuit board 1, as described above, in the LED element mounting region, the LED element 2 is mounted when the LED element 2 is mounted. The second metal wiring part 122 disposed below the support substrate 111 through the support substrate 111 that is transparent or translucent from the gap portion that can be formed between the outer edge and the black layer 14 for improving contrast. Are often exposed from the surface side of the LED dot matrix display device 10 so as to be visible. It is extremely difficult to completely prevent this from the structure of the LED dot matrix display device 10. If the first adhesive layer 131 and the second adhesive layer 132 in FIG. 3 are both transparent or translucent layers, the exposed portion of the first adhesive layer 131 in FIG. The second metal wiring part 122 arranged on the lower layer side can be seen through, and the visibility of the display information of the LED dot matrix display device 10 and the design of the appearance of the device may be significantly reduced. As a means for completely preventing exposure of the metal wiring portion on the lower layer side, a new function for concealment is provided at any position between the contrast improving black layer 14 and the second metal wiring portion 122. The present condition is that the effective means other than arranging an additional layer has not been found.

  On the other hand, in the flexible multilayer circuit board 1 of the present invention, one adhesive layer among the adhesive layers necessarily present as an essential component for maintaining the basic configuration of the flexible multilayer circuit board 1 is used. A black adhesive layer that can also function as a concealing layer without impairing the original adhesive function by incorporating a black or dark pigment into a black adhesive layer It is.

  The black adhesive layer may be any one of the adhesive layers formed between any layers closer to the LED element mounting surface side than the second metal wiring portion 122. One adhesive layer 131 is most preferable. As shown in FIG. 3, by making the first adhesive layer 131 having a small vertical distance from the light emitting surface of the LED element 2 a black adhesive layer having a predetermined blackness, the second metal wiring part 122 is The LED dot matrix display device 10 can be concealed to the extent that it cannot be seen from the surface side, and can greatly contribute to the improvement of the contrast of the display information of the LED dot matrix display device 10. In this way, the flexible multilayer circuit board 1 of the present invention is capable of visually confirming the second metal wiring portion 122 while maintaining the conventional general layer structure without depending on the arrangement of an additional concealing layer or the like. It is possible to prevent deterioration of visibility and design properties due to the exposure and screen display resulting therefrom.

  More specifically, the color tone of the black adhesive layer is more preferably 60 or less, based on JIS-Z8722, and the ΔL * of the black adhesive layer under the condition of a D65 light source and a 10 ° viewing angle is 50 or less. The following is more preferable. By setting the range of ΔL * of the black adhesive layer to this range, as described above, in the LED dot matrix display device 10, the second metal wiring part 122 is not visible from the mounting surface side of the LED element 2. Can be concealed.

  In the flexible multilayer circuit board 1, a third metal wiring portion is further formed on the surface of the insulating protective film 112, and a through-hole capable of conducting the layer with each upper metal wiring portion is further formed. A flexible multilayer circuit board having a three-layer multilayer circuit configuration may also be used. Furthermore, it can also be set as the flexible multilayer circuit board which has a multilayer circuit structure of four or more layers similarly. As long as the above-described black adhesive layer, which is a feature of the present invention, is provided in the above-described manner, all the multilayer circuit boards of the present invention can be used as long as the above-described effects of improving the visibility and design can be obtained. Is within the range.

[Adhesive layer]
In the flexible multilayer circuit board 1, the first metal wiring part 121 and the second metal wiring part 122 are formed on both surfaces of the support substrate 111 by a dry laminating method with an adhesive layer interposed therebetween. As the adhesive forming each of these adhesive layers, any known resin-based adhesive can be used as appropriate. Of these resin adhesives, urethane-based, polycarbonate-based, or epoxy-based adhesives can be particularly preferably used. However, in the flexible multilayer circuit board 1 of the present invention, for the black adhesive forming the adhesive layer as the black adhesive layer, a dark-colored adhesive in which the main material resin contains a black or dark pigment. Is used. Thereby, sufficient concealment function can be provided to the black adhesive layer as described above.

  Addition of a pigment component is not essential for the adhesive used for each adhesive layer that is not a black adhesive. What is necessary is just to contain a suitable quantity as needed suitably in the range which does not inhibit the said effect of this invention, such as a response | compatibility to the request | requirement of the design property of the back side.

  As another option for concealing means, it may be possible to add a pigment to the support substrate 111, but depending on the support substrate 111, the type of pigment, and the pigment content, the thermal expansion coefficient of the support substrate 111 increases, The dimensional stability of the support substrate 111 is deteriorated. Since the flexible multilayer circuit board 1 of the present invention is configured to include the pigment only in the adhesive layer, the occurrence of such a problem can be avoided.

  The support substrate 111 is generally thicker than the adhesive layer from the viewpoint of the mechanical strength of the flexible multilayer circuit board 1. Therefore, a configuration in which a pigment is included in the support substrate 111 to form a concealing layer is not preferable from the viewpoint of economy. In addition, since it is possible to manufacture a flexible multilayer circuit board having the concealability of the second metal wiring part 122 on the lower layer side without adding a process for providing a new layer for the purpose of concealment, Productivity can also be kept good.

(First adhesive layer)
In the flexible multilayer circuit board 1, the first adhesive layer 131 is required to have a predetermined insulating property. Specifically, the first adhesive layer 131 has a volume resistivity measured in accordance with JIS C6481 (in this specification, “volume resistivity” means this value), It may be 10 ⁷ Ω · cm or more, preferably 10 ¹⁶ Ω · cm or more. Thereby, the short circuit of the 1st metal wiring part 121 of the flexible multilayer circuit board 1 can be prevented, and sufficient safety | security can be ensured. The volume resistivity can be measured by using, for example, a digital ultra-high resistance / microammeter 5450/5451 manufactured by ADC.

  Moreover, it is preferable that the first adhesive layer 131 is a black adhesive layer having a blackness of a predetermined level or more after satisfying the above-described conditions regarding the resistance value for insulation. Thereby, the 1st adhesive bond layer 131 can fully exhibit the above-mentioned concealing function. Specifically, when the first adhesive layer 131 is a black adhesive layer, the ΔL * value of the black adhesive layer measured under the conditions of a D65 light source and a 10 ° viewing angle in accordance with JIS-Z8722 is , 60 or less, preferably 10 or less. ΔL * is a parameter representing lightness in color tone, and lightness represents the degree of brightness and darkness of a color. That is, by setting the ΔL * value of the first adhesive layer 131 within the above range, the color of the first adhesive layer 131 is sufficiently dark or black, and is closer to the back side than the first adhesive layer 131. Each layer to be arranged can be hidden invisible.

  When the first adhesive layer 131 is a black adhesive layer, the first adhesive layer 131 is formed of an infrared transmitting adhesive that is an adhesive that transmits near infrared rays having a wavelength of 750 nm to 1500 nm. More preferably. The detail of the pigment component which can make the black adhesive which forms a black adhesive layer into such an infrared rays transparent adhesive is mentioned later.

  The thickness of the first adhesive layer 131 is preferably 2.0 μm or more and 10.0 μm or less, and more preferably 3.0 μm or more and 7.0 μm or less. By setting the thickness of the first adhesive layer 131 to 2.0 μm or more and 10.0 μm or less, it is possible to ensure sufficient concealment properties while ensuring adhesion and durability between the layers. it can.

(Black adhesive)
The black adhesive that can be used to make the predetermined adhesive layer described above, preferably the first adhesive layer 131, a black adhesive comprises a main resin, a curing agent and a solvent, and further, black or dark color. The pigment is contained as an essential component, and, if necessary, other various additives are contained. Examples of other additives include adhesion aids and the like. The black adhesive is preferably a two-component type in which the main resin and the curing agent are mixed immediately before use. When forming the adhesive layer, the main resin reacts with the curing agent to be cross-linked and have a high molecular weight. As such a main material resin, a known resin such as urethane, polycarbonate, or epoxy can be appropriately selected.

  As a black or dark pigment to be included as an essential component in the black adhesive, various conventionally known pigments can be widely used as long as the black adhesive layer satisfying the above-mentioned insulation and color conditions can be formed. Can be used. For example, an inorganic pigment such as carbon black and titanium pigment subjected to insulation reinforcement treatment, or oxazine, pyrrole, quinacridone, azo, perylene, dioxane, isoindolinone, induslen, A dark organic pigment such as quinophthalone, perinone, or phthalocyanine can be used. In addition, pigments obtained by mixing two or more of these pigments can be used in the same manner as long as they satisfy the above conditions of insulation and color.

  In the flexible multilayer circuit board 1, the black adhesive forming the black adhesive layer is an “adhesive that transmits near-infrared rays having a wavelength of 750 nm to 1500 nm”, and the contained pigment has such infrared transparency. More preferably, it is a pigment (hereinafter also referred to as “near-infrared transmitting pigment”). By using such a near-infrared transmitting pigment as a pigment to be added to the black adhesive, it is possible to suppress excessive heat generation due to absorption of near-infrared light in the black adhesive layer having a black or dark color. it can. Therefore, for example, when the first adhesive layer 131 disposed immediately below the LED element 2 is a black adhesive layer, the light emission efficiency of the LED element is reduced due to excessive heat generation in the black adhesive layer. It can be avoided. In the present specification, “a pigment that transmits near infrared rays having a wavelength of 750 nm to 1500 nm” refers to a pigment that transmits near infrared rays of about 65% or more, preferably 75% or more.

  Examples of the near-infrared transmissive pigment that can be preferably contained in the black adhesive include, for example, an oxazine pigment, a benzimidazolone pigment, a pyrrole pigment, a quinacridone pigment, an azo pigment, a perylene pigment, a dioxane pigment, Examples thereof include organic pigments such as isoindolinone pigments, indanthrene pigments, quinophthalone pigments, perinone pigments, and phthalocyanine pigments, or mixtures of these organic pigments.

  As the oxazine-based organic pigment, for example, violet 23 (molecular weight 589), CI direct violet 37 (molecular weight: 789), or a dioxazine-based compound described in JP-A-2003-105217 can be used. . Oxazine-based organic pigments have high UV resistance and can be particularly preferably used, for example, when the LED dot matrix display device 10 is assumed to be used outdoors. Further, when it is contained in a urethane-based, polycarbonate-based, or epoxy-based adhesive layer, the oxazine-based organic pigment itself contributes to the improvement of the adhesiveness, and the adhesiveness can also be improved.

  Among the pigments, a pigment comprising a benzimidazolone pigment and a phthalocyanine pigment is particularly preferable. By using a benzimidazolone pigment and a phthalocyanine pigment, a resin layer having a sufficient concealing property can be obtained even when the thickness of the adhesive layer is reduced. Furthermore, when the benzimidazolone pigment and the phthalocyanine pigment are contained in the urethane, polycarbonate, or epoxy adhesive layer, the adhesive layer has the same adhesiveness as the adhesive layer containing the oxazine pigment. can do.

  The benzimidazolone pigment is a pigment having a benzimidazolone skeleton represented by the following general formula (1). Specifically, PigmentYellow120, PigmentYellow151, PigmentYellow154, PigmentYellow175, PigmentYellow180, PigmentYellow181, PigmentYellow194, Pigment Red175, PigmentRed176, PigmentRed185, PigmentRed208, Pigment Violet32, PigmentOrange36, PigmentOrange62, PigmentOrange72, but PigmentBrown25 etc., not limited thereto . C. from the viewpoint of color gamut. I. Pigment Brown 25 is more preferable.

  The primary particle size of the benzimidazolone pigment is preferably 0.01 μm or more and 0.20 μm. By setting the primary particle size of the benzimidazolone pigment in such a range, the dispersibility in the ink can be improved.

  A phthalocyanine pigment is a pigment having a phthalocyanine skeleton. Specifically, C.I. I. PigmentGreen 7, C.I. I. PigmentGreen 36, C.I. I. Pigment Green 37, C.I. I. PigmentBlue 16, C.I. I. PigmentBlue 75, or C.I. I. Pigment Blue 15 and the like can be mentioned, but the invention is not limited to this. It is preferable to use an amorphous phthalocyanine pigment and a blue pigment.

(Other adhesive layers and other adhesives)
For each of the other adhesive layers that are not the black adhesive layer, it is not essential to exhibit concealment. Therefore, addition of a pigment to each adhesive forming each of these adhesive layers is also optional. Depending on the design requirements, etc., it can be added appropriately within a range that does not impair the required adhesion.

[Black layer for improving contrast]
The contrast enhancement black layer 14 is provided on the surface of the support substrate 111 and on the surface of the first metal wiring part 121 for the purpose of improving the visibility of information displayed by the LED dot matrix display device 10. The portion excluding the mounting region is covered and disposed directly on each surface or via another functional layer.

  The contrast enhancing black layer 14 may be a blackened or darkened insulating protective layer (not shown) arranged to improve the migration resistance of the flexible multilayer circuit board 1.

  Alternatively, the black layer 14 for improving contrast is obtained by laminating a black or dark resin layer or the like on the outermost surface on the insulating protective layer (resist layer) disposed so as to cover the light emitting surface side metal wiring part 121. May be. For example, in a LED dot matrix display device that is assumed to be used outdoors, a wall-like member or the like that surrounds the mounting area of each LED element and also stands for waterproofing the LED element also has a black or dark appearance. Thus, any member that can contribute to the improvement in contrast is included in the black layer 14 for improving contrast.

  Hereinafter, as an example of the embodiment of the flexible multilayer circuit board 1 of the present invention, the case where the contrast improving black layer 14 is a black insulating protective layer in which a black or dark color is imparted to the above insulating protective layer will be described. . Such a black layer 14 for improving contrast that also has an insulating function is formed on the first metal wiring portion 121 and a portion excluding the mounting region of the LED element 2 on the support substrate 111. The contrast improving black layer 14 can be formed by, for example, an insulating thermosetting ink to which an appropriate amount of black or dark pigment similar to that used for the first adhesive described above is added.

  As the thermosetting ink for forming the contrast improving black layer 14, 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. Among these, polyester thermosetting insulating ink is particularly preferable as a material for forming the contrast enhancing black layer 14 of the flexible multilayer circuit board 1 because of its excellent flexibility.

  As for the color of the black layer 14 for improving contrast, the ΔL * value measured under the conditions of a D65 light source and a 10 ° viewing angle in accordance with JIS-Z8722, as with the first adhesive layer 131, is 60 or less, Preferably it is 10 or less. By setting the value of ΔL * of the contrast enhancing black layer 14 within the above range, the color of the contrast enhancing black layer 14 is sufficiently black or dark, and the visibility of display information is sufficiently improved by improving the contrast. be able to. In addition, since ΔL * of the contrast improving black layer 14 is 60 or less, it is possible to prevent difficulty in adjusting the luminance of the display of the LED dot matrix display device 10 due to diffuse reflection of visible light in the same layer. Can do.

  Moreover, in the flexible multilayer circuit board 1, it is more preferable in terms of design that the difference between the color of the first adhesive layer 131 and the color of the black layer 14 for improving contrast is small. Specifically, in accordance with JIS-Z8722 of the black layer 14 for improving contrast and the first adhesive layer 131, both ΔL * values measured under the conditions of a D65 light source and a 10 ° viewing angle are 60 or less, And the thing whose difference of those both values is 20 or less can be mentioned as an example of a thing preferable in designability.

[Support substrate]
The support substrate 111 is not particularly limited, but is preferably made of a thermoplastic resin. The material of the support substrate 111 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.

  The material resin for forming the support substrate 111 has a heat shrinkage starting temperature of 100 ° C. or higher, or a resin whose heat resistance is improved so that the temperature becomes 100 ° C. or higher by the above-described annealing treatment or the like. Is preferred. Usually, the peripheral portion reaches a temperature of about 90 ° C. by the heat generated from the LED element 2. From this viewpoint, it is preferable that the thermoplastic resin forming the support substrate 111 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 support substrate 111 is required to be an insulating resin that can provide the insulating properties required for the flexible multilayer circuit board 1 when integrated as the LED dot matrix display device 10. In general, the support substrate 111 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 support substrate 111 is not particularly limited. However, when a flexible resin substrate is used, the thickness is approximately 10 μm or more and 100 μm or less from the viewpoint of balance between heat resistance, insulation, and manufacturing cost. It is preferable. 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.

  Note that the material, thickness, and the like of the insulating protective film 112 can be the same as those of the support substrate 111 described above. However, when the insulating protective film 112 is disposed on the outermost layer of the flexible multilayer circuit board 1, it is preferable to have weather resistance as a protective layer. In this case, a resin film made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide resin (PI) or the like can be preferably used as the insulating protective film 112 that also functions as a back surface protective layer.

[Metal wiring section]
The first metal wiring part 121 and the second metal wiring part (hereinafter collectively referred to as “metal wiring part 13”) are conductive materials such as metal foils on both surfaces of the support substrate 111 in the flexible multilayer circuit board 1. It is a wiring pattern formed with a base material.

  The arrangement of the metal wiring portion 13 is not limited to a specific arrangement in the horizontal direction and the vertical direction as long as the LED elements 2 can be mounted in a matrix at a desired pitch. Arbitrary arrangements including the same arrangement as the substrate can be adopted.

  However, in the flexible multilayer circuit board 1, it is preferable that at least 80% or more, preferably 90% or more preferably 95% or more of one surface of the support substrate 111 is covered with the metal wiring portion 13. . Thereby, it can contribute to the improvement of the heat dissipation requested | required in the LED display apparatus which uses the metal wiring part 13 and a flexible multilayer circuit board.

The metal thermal conductivity λ constituting the metal wiring part 13 is preferably 200 W / (m · K) or more and 500 W / (m · K) or less, and preferably 300 W / (m · K) or more and 500 W / (m · K) or less. More preferred. The metal resistivity R constituting the metal wiring part 13 is preferably 3.00 × 10 ⁻⁸ Ω · m or less, more preferably 2.50 × 10 ⁻⁸ Ω · m or less. 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. Can be used. According to this, for example, in the case of copper, the thermal conductivity λ is 403 W / (m · K), and the electrical resistivity R is 1.55 × 10 ⁻⁸ Ω · m. Thereby, both heat dissipation and electrical conductivity can be achieved. More specifically, the heat dissipation from the LED element 2 is stabilized and an increase in electrical resistance can be prevented, so that the variation in light emission between the LED elements 2 is reduced. In addition, the lifetime of the LED element is extended. Further, since deterioration of peripheral members such as a substrate due to heat can be prevented, the product life of the LED dot matrix display device 10 using the flexible multilayer circuit substrate 1 can be extended.

  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 current resistance required for the flexible multilayer circuit board 1 and is not particularly limited, but examples include a thickness of 10 μm to 50 μm. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 13 is preferably 10 μm or more. Further, if the metal layer thickness is less than the lower limit, the influence of thermal contraction of the substrate is large, and the warp after the treatment is likely to increase during the solder reflow process. From this viewpoint, the thickness of the metal wiring portion 13 is 10 μm. The above is preferable. When the thickness is 50 μm or less, sufficient flexibility can be maintained, and a decrease in handling property due to an increase in weight can be prevented.

  In addition, by blackening the surface of the first metal wiring part 121, adverse effects due to the exposure of the first metal wiring part 121 are suppressed, and the visibility of the display information of the LED dot matrix display device 10 and the appearance of the device are designed. Can be further improved. In the etching process for forming the first metal wiring part 121, the blackening process is a blackening process for blackening the surface of the metal constituting the metal foil in a state where a mask is present on the surface of the metal foil forming the wiring part. This can be done by blackening the inside of the halftone dots formed on the metal surface by half-etching with an agent. As the blackening agent, an alkaline blackening solution, nickel plating, or the like can be used. Note that “blackening” a metal surface is not limited to the meaning of blackening the metal surface, but the original metal surface is colored to make the metal surface the original metal. It means to be able to absorb more light than the surface. For this reason, “blackening” the surface of the metal is a concept including making the surface of the metal dark brown or brown.

[Through hole]
As described above, the flexible multilayer circuit board 1 is formed with the through-hole 15 that conducts the first metal wiring part 121 and the second metal wiring part 122. The through hole 15 is a cylindrical through hole having a diameter of about 0.1 mm to 0.7 mm formed in the flexible multilayer circuit board 1, and the inside thereof is filled with a conductive material 151, or The inner wall of the through hole 15 is applied by plating or the like. The conductive material 151 ensures conduction between all the metal wiring portions, in addition to between the first metal wiring portion 121 and the second metal wiring portion 122. Moreover, since the through hole 15 has high thermal conductivity, it also has a function of promoting heat dissipation as a heat conduction path between the metal wiring portions.

<LED dot matrix display device>
The LED dot matrix display device 10 shown in FIG. 1 can be obtained by mounting the LED element 2 on the flexible multilayer circuit board 1 and integrating it with other necessary members.

[LED element]
The LED element 2 which comprises the LED dot matrix display apparatus 10 by being mounted in the flexible multilayer circuit board 1 is a light emitting element using the light emission in the PN junction part where the P-type semiconductor and the N-type semiconductor were 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.

  Bonding of the LED element 2 to the first metal wiring part 121 in the flexible multilayer circuit board 1 can be preferably performed by solder bonding via the solder layer 16. 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 first metal wiring part 121 via solder, and then the flexible multilayer circuit board is transported into the reflow furnace, and hot air of a predetermined temperature is applied to the metal wiring part 13 in the reflow furnace. In this method, the solder paste is melted by spraying and the LED element 2 is soldered to the metal wiring portion 13. The laser method is a method of soldering the LED element 2 to the metal wiring portion 13 by locally heating the solder with a laser.

<Manufacture of flexible multilayer circuit board>
The manufacturing method of the flexible multilayer circuit board is not particularly limited, and can be manufactured by a conventionally known electronic board manufacturing method. For example, as described in Patent Documents 3 and 4 and the like, it can be manufactured by a conventional method through a process of forming each metal wiring part on each surface of the substrate film by an etching process. In this etching process, the unmasked portion of the copper foil or the like is removed to form a non-conductive portion, but the adhesive layer immediately below the portion remains on the support substrate, and the completed flexible multilayer circuit The adhesive layer is present on substantially the entire surface of the support substrate 111 of the substrate 1.

  The flexible multilayer circuit board of the present invention described above and the LED dot matrix display device using the same have the following effects.

(1) A black color in which one of the adhesive layers of the flexible multilayer circuit board 1 has a ΔL * value of 60 or less measured according to a D65 light source and a 10 ° viewing angle according to JIS-Z8722. An adhesive layer was obtained.
Thereby, the fall of the visibility of the LED dot matrix display apparatus 10 accompanying the multilayering of the circuit structure of a wiring board can be avoided.

(2) The first adhesive layer 131 having a small vertical distance from the light emitting surface of the LED element 2 was used as a black adhesive layer having a predetermined blackness.
As a result, the second metal wiring part 122 is concealed to such an extent that it cannot be seen from the surface side of the LED dot matrix display device 10, and contributes greatly to improving the contrast of display information of the LED dot matrix display device 10. it can.

(3) The black adhesive forming the black adhesive layer was an infrared transmitting adhesive that transmits near infrared rays having a wavelength of 750 nm to 1500 nm.
Thereby, for example, in a structure in which a black or dark adhesive layer is disposed immediately below the LED element 2, it is possible to avoid a decrease in the luminous efficiency of the LED element due to excessive heat generation in the black or dark color layer. it can.

(4) The pigment to be added to the black adhesive was a pigment component comprising an oxazine pigment having high UV resistance and a relatively low degree of decrease in adhesion due to pigment addition.
Thereby, in addition to the effects of the inventions (1) to (3), the durability of the black adhesive layer can be further improved.

(5) A black adhesive containing a resin component and a pigment component comprising a benzimidazolone pigment and a phthalocyanine pigment, and containing the benzimidazolone pigment and the phthalocyanine pigment in the pigment component The infrared ray transmitting adhesive having a mass ratio of 30:70 to 70:30 in terms of mass ratio.
Thereby, in addition to the effects of the inventions of (1) to (3), even when the thickness of the support substrate and the adhesive layer is reduced, the resin layer can be sufficiently concealed. Therefore, it can be set as a flexible multilayer circuit board preferable from a viewpoint of productivity. Further, when the benzimidazolone pigment and the phthalocyanine pigment are contained in the adhesive layer, the adhesive layer can have the same adhesiveness as the adhesive layer containing the oxazine pigment.

(6) The colors of the contrast improving black layer 14 and the first adhesive layer were as follows. That is, in accordance with JIS-Z8722, the ΔL * values of both layers measured under the conditions of a D65 light source and a 10 ° viewing angle are both 60 or less, and the difference between these values is 20 or less. I made it.
Thereby, while enjoying the effects of the inventions of (1) to (5), the design of the LED dot matrix display device can be further improved by unifying the color of the black or dark portion.

  (7) The same pigment was used as the pigment for developing blackness in the black layer 14 for improving contrast and the black adhesive layer. Thereby, the effect of the invention of (6) can be expressed more stably.

(8) The 1st metal wiring part 121 was comprised with the copper foil by which the surface was blackened.
Thereby, the effect of the improvement of the visibility and the design property of the display in invention of (1) to (7) can further be heightened.
(9) A flexible multilayer circuit board in which three or more layers of metal wiring portions are arranged.
Accordingly, the inventions (1) to (8) can be applied to various multi-layer type flexible multilayer circuit boards. For example, when a wiring structure capable of performing more complicated and precise lighting control is required, such as when used as a wiring board of a multi-color type LED dot matrix display device, the description in (1) to (8) A flexible multilayer circuit board can be preferably used.

(10) An LED dot matrix display device in which an LED element is mounted on the flexible multilayer circuit board according to any one of (1) to (9).
Thus, in an LED dot matrix display device that needs to be electrically connected to each element that enables light emission control of a large number of LED elements, while enjoying the effects of the inventions (1) to (9), a multilayer circuit configuration It is possible to avoid the deterioration of the visibility and design properties associated with the conversion.

  As described above, according to the flexible multilayer circuit board of the present invention and the LED dot matrix display device using the same, it is possible to avoid deterioration in visibility and design properties due to the multilayered circuit configuration in the LED dot matrix display device. be able to.

DESCRIPTION OF SYMBOLS 1 Flexible multilayer circuit board 111 Support substrate 112 Insulation protective film 121 1st metal wiring part 122 2nd metal wiring part 131 1st adhesive layer 132 2nd adhesive layer 133 3rd adhesive layer 14 Black layer 15 for contrast improvement Hall 151 Conductive material 16 Solder layer 2 LED element 10 LED dot matrix display device

Claims (10)

A flexible multilayer circuit board for LED elements,
A flexible support substrate;
A first metal wiring portion laminated on one surface of the support substrate via a first adhesive layer;
A second metal wiring portion laminated on the other surface of the support substrate via a second adhesive layer;
The outermost layer on the LED element mounting surface side of the flexible multilayer circuit board is provided with a black layer for improving contrast, covering a portion excluding the LED element mounting area, and
In the flexible multilayer circuit board, at least any one of the adhesive layers formed between the layers closer to the LED element mounting surface than the second metal wiring portion is JIS- A flexible multilayer circuit board having a ΔL * value measured according to a condition of a D65 light source and a 10 ° viewing angle of 60 or less in accordance with Z8722.   The flexible multilayer circuit board according to claim 1, wherein the first adhesive layer is the black adhesive layer.   The flexible multilayer circuit board according to claim 1 or 2, wherein the black adhesive forming the black adhesive layer is an infrared transmitting adhesive that transmits near infrared rays having a wavelength of 750 nm to 1500 nm.   4. The flexible multilayer circuit board according to claim 1, wherein the black adhesive is an infrared transmitting adhesive containing a resin component and a pigment component containing an oxazine pigment. 5.   The black adhesive contains a resin component and a pigment component comprising a benzimidazolone pigment and a phthalocyanine pigment, and the content of the benzimidazolone pigment and the phthalocyanine pigment in the pigment component The flexible multilayer circuit board according to any one of claims 1 to 3, which is an infrared transmitting adhesive having a mass ratio of 30:70 to 70:30.   The contrast improving black layer and the black adhesive layer both have a ΔL * value of 60 or less according to JIS-Z8722 and measured under the conditions of a D65 light source and a 10 ° viewing angle. The flexible multilayer circuit board according to claim 1, wherein the difference between the two values is 20 or less.   The flexible multilayer circuit board according to any one of claims 1 to 6, wherein the contrast-improving black layer and the black adhesive layer are formed to include the same dark pigment.   The flexible multilayer circuit board according to claim 1, wherein the first metal wiring part is a copper foil whose surface is blackened.   The flexible multilayer circuit board according to claim 1, wherein a third metal wiring portion is further laminated on the surface of the second metal wiring portion via an insulating protective film.   An LED dot matrix display device comprising an LED element mounted on the flexible multilayer circuit board according to claim 1.

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