JP2016197675A - Flexible multilayer circuit board for LED element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible multilayer circuit board that can reduce a bending damage risk caused by flexibility of a support board and the difference in bending elastic modulus between the support board and a metal wiring portion.SOLUTION: A metal wiring portion 12 provided to at least one outermost surface and other outermost surface of a support substrate 111 is formed by a plurality of conductive plate portions, and a flexible multilayer circuit board is disposed in a positional relationship satisfying a predetermined condition of minimizing an overlap portion in plan view of the multilayer circuit board between an insulating slit portion as a nonconductive portion between conductive plate portions constituting one metal wiring portion 12 and an insulating slit portion as a nonconductive portion between the conductive plate portions constituting the other metal wiring portion 12.SELECTED DRAWING: Figure 4

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).

  Further, in the LED dot matrix display device, in many cases, the conduction to each element that enables light emission control of a large number of LED elements is a multi-layer circuit board in which metal wiring portions are arranged on both sides of the support substrate ( Patent Document 2) is 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.

  As a further improvement of such a multilayer circuit board, a flexible multilayer circuit board in which metal wiring portions are arranged on both surfaces of a flexible support substrate such as a resin film has also been proposed (see Patent Document 3). ). According to such a flexible multilayer circuit board, various processes for thinning, increasing the arrangement density of the LED elements 2 or changing the shape and size of the support substrate can be easily performed. The degree of freedom in design of the display device is greatly expanded.

  However, in these flexible multilayer circuit boards, due to the flexibility of the support substrate and the difference in flexural modulus between the support substrate and the metal wiring part in any process until the LED dot matrix display device is incorporated. As a result, there are some cases in which the LED dot matrix display device is seriously damaged, such as bending of the substrate that cannot be restored or damage to the mounting portion of the LED element. This is one of the factors that hinder the improvement of the productivity of the LED dot matrix display device.

JP 2006-145682 A JP 2001-345485 A JP 2010-140989 A

  The present invention has been made in view of the above situation, and occurs due to the flexibility of the support substrate and the difference in flexural modulus between the support substrate and the metal wiring portion in the flexible multilayer circuit board. The aim is to reduce the risk of bending damage.

  As a result of intensive research, the inventors of the present invention do not allow the insulating slit portions to overlap each other in the vertical direction in the metal wiring portions arranged at different positions in the vertical direction in the flexible multilayer circuit board for LED elements. As a result, it was found that the risk of bending damage can be reduced, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A flexible multilayer circuit board for LED elements, which is horizontally arranged at a plurality of vertical positions including at least a flexible support board and one outermost surface and the other outermost surface of the support board. An insulating slit portion that is a non-conductive portion between the conductive plate portions that constitute one metal wiring portion, and each of the metal wiring portions is formed by a plurality of conductive plate portions. And the insulating slit portion, which is a non-conductive portion between the conductive plate portions constituting the other metal wiring portion, are arranged so as to have a positional relationship that satisfies the following condition (A) or (B): Flexible multilayer circuit board.
(A) In an arbitrary group selected from among insulating slit portions that are parallel to each other and at different vertical positions, at least one insulating slit portion is different from other insulating slit portions in plan view of the multilayer circuit board. It is arranged in a horizontal position that does not overlap.
(B) In the arbitrary group, one insulating slit portion forms an overlapping portion by being disposed at a horizontal position where a portion thereof overlaps with another insulating slit portion in plan view of the multilayer circuit board. And
In addition, the overlapping portion does not communicate with the overlapping portion in another adjacent insulating slit portion in a plan view of the multilayer circuit board.

  (2) The flexible multilayer circuit board according to (1), wherein the metal wiring portions are all formed by patterning having the same shape.

  (3) The flexible multilayer circuit board according to (1) or (2), wherein a surface area of the metal wiring portion is an area of 80% or more in an area ratio with respect to a surface area of the support substrate.

  (4) The flexible multilayer circuit board according to any one of (1) to (3), wherein the support substrate is made of a single resin film having a diagonal length of 65 inches or more.

  (5) An LED dot matrix display device comprising an LED element mounted on the flexible multilayer circuit board according to any one of (1) to (4).

  According to the present invention, in the flexible multilayer circuit board, the risk of bending damage of the substrate caused by the flexibility of the support substrate and the difference in flexural modulus between the support substrate and the metal wiring portion is reduced. Can do.

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 the elements on larger scale of the surface of the mounting surface of the LED element of the LED dot matrix display apparatus of this invention, and is drawing used for description of the arrangement | positioning aspect of the metal wiring part of the flexible multilayer circuit board of this invention. It is a flexible multilayer circuit board of this invention, Comprising: It is a typical partial perspective plan view about an example of a flexible multilayer circuit board provided with the metal wiring part which satisfy | fills conditions (A). It is a flexible multilayer circuit board of this invention, Comprising: It is a typical partial perspective plan view about an example of a flexible multilayer circuit board provided with the metal wiring part which satisfy | fills conditions (B). It is a top view with which it uses for description about other one Embodiment about the shape of the metal wiring part of the flexible multilayer circuit board of this invention.

  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 light-emitting surface side metal wiring portion 121 disposed on one outermost surface. And the metal wiring part 122 of the back side is laminated | stacked on the other outermost surface on the opposite side to the surface where the metal wiring part 121 of the light emission surface side is arrange | positioned. In addition, an insulating layer (not shown) such as a solder resist is usually formed on the surface of the metal wiring portion 122 on the back side, and further, if necessary, made of a resin base material or the like. Further, an insulating protective film 112 having a function as the above is further laminated through an adhesive layer 133. Also, the flexible multilayer circuit board 1 is formed with a through hole 15 that conducts between the metal wiring portion 121 on the light emitting surface side and the metal wiring portion 122 on the back surface side.

  In the case where the flexible multilayer circuit board 1 has a two-layer metal wiring board, as shown in FIG. 2, it is on the surface of the support substrate 111 and on the surface of the metal wiring part 121 on the light emitting surface side. The contrast enhancement black layer 14 is disposed directly or via another functional layer so as to cover a portion excluding the LED mounting region. 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 this specification is a region composed of a portion to be joined to the metal wiring part 121 on the light emitting surface side of the LED element 2 in the flexible multilayer circuit board 1 and its peripheral portion. It refers to a region directly below the space required as an optical path to the outside of the light emitted from the LED element 2 and the installation of the LED element 2. In FIG. 2, a portion where the contrast improving black layer 14 is not disposed on the surface of the metal wiring portion 121 on the light emitting surface side is an LED element mounting region.

  The flexible multilayer circuit board 1 may have three or more layers of metal wiring portions. In this case, the light emitting surface of the flexible multilayer circuit board 1 is closer to the back side of the flexible multilayer circuit board 1 than the metal wiring part 121 on the light emitting surface side of the flexible multilayer circuit board 1 and more than the metal wiring part 122 on the back side. An intermediate metal wiring portion (not shown) is formed at a vertical position near the side. Then, by forming a through-hole capable of conducting the intermediate metal wiring portion and other metal wiring portions, a flexible multilayer circuit board having a three-layer multilayer circuit configuration can be obtained. Furthermore, it can also be set as the flexible multilayer circuit board which has a multilayer circuit structure of four or more layers similarly. In the present specification, in the flexible multilayer circuit board 1 having a multilayer circuit configuration of three or more layers, the metal wiring portion 121 on the light emitting surface side disposed on the surface on the light emitting surface side, and the outermost layer on the back surface side are disposed. Any of the metal wiring portions stacked between any of the layers located between the rear-side metal wiring portion 122 and the rear-side metal wiring portion 122 is referred to as an intermediate metal wiring portion.

  The size of the flexible multilayer circuit board 1 is not particularly limited, but the present invention is a large-sized LED display device that has a low manufacturing efficiency with a conventional rigid-type wiring board, or a display device having a curved display surface. Widely applicable to etc. For example, a large LED dot matrix display device 10 having a diagonal length of 65 inches or more and about 40 LED elements 2 mounted in the X direction, about 40 in the X direction and about 30 in the Y direction. In addition, the flexible multilayer circuit board 1 of the present invention can be preferably used. The planar shape of the flexible multilayer circuit board of the present invention is not necessarily limited to a rectangular shape. In the present specification, “the length of the diagonal line is 65 inches or more” means, for example, the length of the major axis when the flexible multilayer circuit board is elliptical.

[Support substrate]
The support substrate 111 is not particularly limited as long as it is a film or sheet that can maintain the flexibility of the flexible multilayer circuit board 1. For example, a resin film can be preferably used from a thermoplastic resin. However, the material of the support substrate 111 is required to have certain 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. Polyethylene terephthalate (PET) whose flame retardancy is improved by adding a flame retardant inorganic filler or the like can also be used 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 part 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. .

In addition, the support substrate 111 is required to be a 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 has a volume resistivity measured according to JIS C6481 (in this specification, “volume resistivity” means this value) of 10 ¹⁴ Ω · It is preferably cm or more, and more preferably 10 ¹⁸ Ω · cm or more. The volume resistivity can be measured by using, for example, a digital ultra-high resistance / microammeter 5450/5451 manufactured by ADC.

  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 in the outermost layer of the flexible multilayer circuit board 1, it is preferable that the insulating protective film 112 also has weather resistance and water vapor barrier properties 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 metal wiring part 121 on the light emitting surface side and the metal wiring part 122 on the back side (hereinafter, both the wiring part and the intermediate metal wiring part are collectively referred to as “metal wiring part 12”) are electrically conductive such as copper foil. In the flexible multilayer circuit board 1, the wiring pattern is formed on both surfaces of the support substrate 111. The metal wiring part 12 has a function of supplying electricity by passing a necessary current by conducting between, for example, 1000 or more LED elements 2, and also exhibits an effect as a heat radiating part in the flexible multilayer circuit board 1. Is. And the flexible multilayer circuit board 1 of this invention has the main characteristics that the bending risk is reduced by limiting the arrangement | positioning of the metal wiring part to an original aspect. Details of the arrangement of the metal wiring portion will be described below.

  As shown in FIG. 3, the metal wiring part 12 is formed on the surface of the support substrate 111 of the flexible multilayer circuit board 1 by a polygonal conductive plate part 123 (on the back side) formed on the light emitting surface side by a conductive base material. Is a wiring pattern comprising the conductive plate portion 124) shown in FIG. The planar view shape of the conductive plate portion constituting the metal wiring portion 12 is a convex polygon such as a regular polygon as long as it is a polygonal shape capable of conducting between the LED elements 2 arranged in a matrix. Or a concave polygon as shown in FIG.

  As shown in FIG. 3 and the like, the metal wiring portion 12 is a portion where the LED element 2 is joined to the metal wiring portion 12 so that the LED element 2 can be conducted in both XY directions on the matrix. It is preferable that the arrangement is repeated. As shown in FIG. 3 and the like, the basic unit of mounting is a pair of adjacent conductive plate portions 123 in the flexible multilayer circuit board 1 on the light emitting surface side, and an insulating slit portion on the light emitting surface side that is a gap portion therebetween. This refers to the part consisting of 123X and 123Y. The same applies to the back side.

  In detail, the insulating slit portion is a non-formation portion of the metal wiring portion 12 on the surface of the support substrate 111 on which the metal wiring portion 12 is arranged in the flexible multilayer circuit board 1 as shown in FIGS. 4 and 5. These are non-conductive portions between the pair of adjacent conductive plate portions 123 and 124, and refer to the insulating slit portions 123X and 123Y on the light emitting surface side and the insulating slit portions 124X and 124Y on the back surface side.

  In addition, as shown in FIG. 3, the metal wiring portion 12 includes connector wiring for connecting between conductive plate portions arranged in different rows or columns in the matrix-like arrangement in addition to the above-described basic unit of mounting. In the end portion of the row or column, the LED dot matrix display device 10 is configured to include a terminal for electrical connection with an external power source or the like. In the flexible multilayer circuit board 1, the conductive plate portions 123 and 124 that constitute the metal wiring portion 12, the connector wiring, the arrangement of the terminals, and the combination thereof are highly flexible. Either a series connection or a parallel connection is possible, and a wiring in which both connections are optimally combined according to the characteristics required of the LED dot matrix display device 10 after mounting can be obtained.

  The metal wiring part 12 of the flexible multilayer circuit board 1 according to the present invention has the insulating slit part arrangement condition described in detail below, in order to reduce the risk of bending damage described above. The arrangement of the metal wiring portion is optimized to a specific arrangement so as to satisfy the above. The arrangement condition of the insulating slit part peculiar to the present invention is that the insulating slit part (for example, on the front side) is a non-conductive part between the conductive plate parts constituting one metal wiring part (for example, the front side metal wiring part 121). Insulating slit portion 123Y) and an insulating slit portion (for example, the back side insulating slit portion 124Y) that is a non-conductive portion between the conductive plate portions constituting the other metal wiring portion (for example, the back side metal wiring portion 122) Is arranged so as to have a positional relationship that satisfies the following condition (A) or (B).

(Condition (A))
Condition (A) is as follows.
“In an arbitrary group selected from among insulating slit portions that are parallel to each other and at different vertical positions, at least one insulating slit portion is different from other insulating slit portions in plan view of the multilayer circuit board. It is placed in a horizontal position that does not overlap. "

  FIG. 4 is an example of the arrangement of the metal wiring portions 12 that satisfy the condition (A). In FIG. 4, the front-side insulating slit portion 123 </ b> X and the rear-side insulating slit portion 124 </ b> X that are parallel to each other are arranged at horizontal positions that do not overlap in a plan view of the flexible multilayer circuit board 1. The same applies to the insulating slit portion 123Y and the insulating slit portion 124Y, and also between other insulating slits that are parallel to each other and at different vertical positions. In FIG. 4, the metal wiring portion has a two-layer structure, but the condition (A) is similarly applied even when one or a plurality of intermediate metal layers are disposed thereon. That is, if all the insulating slit portions formed in the same direction across all layers in the vertical direction are in the overlapping position, the risk of bending increases, and therefore the purpose of the condition (A) is to avoid this. It is.

  In order to further reduce the above-described bending risk, all the insulating slit portions that satisfy the above condition (A), are parallel to each other, and are at different vertical positions, are multilayer circuit boards. It is more preferable that they are arranged at horizontal positions that do not overlap each other in plan view.

(Condition (B))
Condition (B) is as follows.
“In an arbitrary group selected from among the insulating slit portions that are parallel to each other and at different vertical positions, one insulating slit portion and one of the other insulating slit portions in a plan view of the multilayer circuit board. The overlapping part is formed by being arranged in the horizontal position where the parts overlap,
In addition, the overlapping portion does not communicate with the overlapping portion in another adjacent insulating slit portion in a plan view of the multilayer circuit board. "
Here, “adjacent insulating slit portion” means that the other conductive plate portion adjacent to one conductive plate portion constituting the outer edge of one insulating slit portion constitutes the outer edge. This refers to an insulating slit portion other than one insulating slit portion.

FIG. 5 is an example of the arrangement of the metal wiring portions 12 that satisfy the condition (B). The arrangement of the metal wiring portion in FIG. 5 is half the width of the insulating slit portion on the light emitting surface side only in the X direction while maintaining the shape of the metal wiring portion 121 on the light emitting surface side from the arrangement shown in FIG. This is an arrangement in which the positions are moved in parallel in the direction in which the arrangement positions overlap by the distance of. In FIG. 5, a part of the insulating slit part 123 </ b> Y on the front surface side and the insulating slit part 124 </ b> Y on the back surface side which are parallel to each other partially overlap in a plan view of the flexible multilayer circuit board 1. However, the overlapping portion S ₀ does not communicate with the overlapping portions S ₁ and S ₂ in other adjacent insulating slit portions. The same applies to the insulating slit portion 123X and the insulating slit portion 124X, and also between other insulating slits that are parallel to each other and at different vertical positions. In FIG. 5, the metal wiring portion has a two-layer structure, but the condition (B) is similarly applied even when one or a plurality of intermediate metal layers are disposed thereon. That is, when a part of the insulating slit portion formed in the same direction over the entire layer in the vertical direction overlaps, and the overlapping portion communicates with an overlapping portion of a plurality of adjacent insulating slit portions. Since the risk of bending increases, the purpose of the condition (B) is to avoid this.

  In order to further reduce the above-described bending risk, the above-described condition (B) is satisfied, and further, all the above-described overlapping portions are adjacent to each other in the plan view of the multilayer circuit board. It is more preferable not to communicate with the same overlapping portion in the portion.

  Moreover, although the slit part along the X direction Y direction in the case where the support substrate 111 is rectangular as an insulating slit part was illustrated above, an insulating slit part is not restricted to this. For example, a slit portion formed in an oblique direction with respect to the support substrate and a slit portion including a curve are also included in the insulating slit portion referred to in the present invention.

  The flexible multilayer circuit board 1 does not require special additional shape processing different from the general shape with respect to the shape of the metal wiring portion, and only by optimizing the arrangement position thereof, the flexible multilayer circuit board 1 The risk of bending damage can be significantly reduced. For example, as shown in FIG. 4, the metal wiring part 121 on the light emitting surface side and the metal wiring part 122 on the back surface side are formed by the same patterning composed of repeated conductive plate parts 123 and 124 having the same shape. Even in such a case, by optimizing the arrangement, the above arrangement conditions can be satisfied, and the above risk can be realized without reducing productivity and adding processing costs. Specifically, as long as the above-mentioned “arrangement conditions of the insulating slit portion peculiar to the present invention” are satisfied, the flexible multilayer circuit board 1 is arranged such that the portion that is likely to be a starting point of bending damage, that is, the insulating slit portion overlaps in the vertical direction. You can eliminate the part that is. Therefore, the flexible multilayer circuit board 1 can be bent to reduce the risk of damage.

  The width of the insulating slits 123X, 123Y, 124X, 124Y is preferably 0.1 mm or more and 1.0 mm or less, and more preferably 0.15 mm or more and 0.5 mm or less. Further, since the width of the insulating slit portions 123X, 123Y, 124X, and 124Y is 0.5 mm or less, it is possible to transfer heat between the conductive plate portions. For example, when local heat generation occurs in a large-sized LED dot matrix display device, the preferred heat transfer is a conductive plate that remains at a relatively low temperature from a conductive plate portion at a relatively high temperature. The effect | action which moves the heat to a part is mentioned. Thereby, the local high temperature in the large-sized LED dot matrix display device 10 can be dissipated to the entire flexible multilayer circuit board 1, and the function deterioration or failure of each LED element 2 due to the local temperature rise can be prevented.

  The flexible multilayer circuit board 1 is such that 80% or more, preferably 90%, more preferably 95% or more of the surface of the support substrate 111 on the light emitting surface side is covered with the metal wiring part 121 on the light emitting surface side. It is preferable that the metal wiring part on the light emitting surface side is arranged so that Further, the back side of the support substrate 111 is generally 90% or more, preferably 95% or more, because there are less restrictions on mounting LED elements, for example, and the degree of freedom of arrangement is higher than the metal wiring part on the light emitting surface side. More preferably, the rear-side metal wiring portion 122 is arranged so that the range of 98% or more is covered by the rear-side metal wiring portion 122. Furthermore, when the intermediate metal wiring portion is disposed, it is preferable that all the intermediate metal wiring portions are disposed so as to have an area of 85% or more in the area ratio with respect to the surface area of the support substrate 111. By arranging the metal wiring portion in this way, the heat generated on the light emitting surface side can be moved to the back side and released with extremely high efficiency.

  200 W / (m · K) or more and 500 W / (m · K) or less is preferable, and 300 W / (m · K) or more and 500 W / (m · K) or less is preferable. More preferred. The metal resistivity R constituting the metal wiring part 12 is preferably 3.00 × 10 −8 Ω · m or less, and 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., 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, 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 12 include metal foils such as aluminum, gold, silver, and copper. The thickness of the metal wiring part 12 may be set as appropriate according to the magnitude of the withstand current 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 part 12 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 12 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.

[Adhesive layer]
In the flexible multilayer circuit board 1, the formation of the metal wiring part 121 on the light emitting surface side and the metal wiring part 122 on the back surface side on both surfaces of the support substrate 111 are both adhesive layers 131 and 132 (hereinafter, all adhesives including them). It is preferable to carry out by the dry laminating method through the layers collectively referred to as “adhesive layer 13”. As the adhesive forming these adhesive layers 13, any 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. Further, if necessary, a colored pigment can also be added. For example, the design of the surface of the LED dot matrix display device 10 can be improved by adding a black pigment to the adhesive layer 131 immediately below the metal wiring part 121 on the light emitting surface side. The same applies to the adhesive used when the intermediate metal wiring portion is disposed.

In the flexible multilayer circuit board 1, the adhesive layer 13 is required to have a predetermined insulating property. Specifically, the adhesive layer 13 may have a volume resistance value measured according to JIS C6481 of 10 ⁷ Ω · cm or more, preferably 10 ¹⁶ Ω · cm. Thereby, the short circuit of the metal wiring part 12 can be prevented and sufficient safety | security can be ensured.

  The adhesive forming the adhesive layer 13 includes a main resin, a curing agent, and a solvent, and also includes various other additives as necessary. Examples of other additives include colored pigments and adhesion aids. The 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.

[Black layer for improving contrast]
The black layer 14 for improving contrast is provided on the surface of the support substrate 111 and the surface of the metal wiring part 121 for the purpose of improving the visibility of information displayed by the LED dot matrix display device 10 and for mounting LEDs. The portions excluding the regions are covered and arranged on each of these surfaces directly or via other functional layers.

  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 contrast improving black layer 14 is obtained by laminating a black or dark resin layer or the like on the outermost surface of the insulating protective layer (resist layer) disposed so as to cover the metal wiring part 121 on the light emitting surface side. There 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 metal wiring part 121 and the support substrate 111 except for the mounting area of the LED element 2. 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.

  About the color of the black layer 14 for contrast improvement, it is preferable that (DELTA) L * value measured by the conditions of D65 light source and 10 degree viewing angle based on JIS-Z8722 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.

[Through hole]
As described above, the flexible multilayer circuit board 1 is formed with the through hole 15 that conducts between the metal wiring part 121 on the light emitting surface side and the metal wiring part 122 on the back surface side. 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 the metal wiring portions, such as between the metal wiring portion 121 on the light emitting surface side and the metal wiring portion 122 on the back surface side. 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.

[Solder layer]
In the flexible multilayer circuit board 1, the metal wiring portion 12 and the LED element 2 are joined through the solder layer 16. Details of the soldering method will be described later, but can be roughly classified into either a reflow method or a laser method.

<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.

  The LED element 2 can be preferably bonded to the metal wiring part 121 on the light emitting surface side in the flexible multilayer circuit board 1 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 metal wiring part 121 on the light emitting surface side via solder, and then the flexible multilayer circuit board is transported into the reflow furnace, and the metal wiring part 12 is heated to a predetermined temperature in the reflow furnace. This is a method of melting the solder paste by blowing hot air and soldering the LED element 2 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.

<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 Document 3, 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) In the flexible multilayer circuit board 1 for LED elements, the insulating slit part which is a non-conduction part between the said conductive plate part which comprises one metal wiring part, and the said conductive plate which comprises another metal wiring part The flexible multilayer circuit board arrange | positioned so that the insulation slit part which is a non-conduction part between parts may become the positional relationship which satisfy | fills the following (A) or (B) conditions.
(A) In any arbitrary group selected from insulating slit portions that are parallel to each other and at different vertical positions, at least one insulating slit portion is different from other insulating slit portions of the multilayer circuit board. It is arranged in a horizontal position that does not overlap in plan view.
(B) In the arbitrary group, one insulating slit portion forms an overlapping portion by being disposed at a horizontal position where a portion thereof overlaps with another insulating slit portion in plan view of the multilayer circuit board. In addition, the overlapping portion does not communicate with the overlapping portion in another adjacent insulating slit portion in a plan view of the multilayer circuit board.
Thus, the flexible multilayer circuit board 1 does not require special additional shape processing different from the general shape with respect to the shape of the metal wiring portion 12, and by optimizing the arrangement, the flexible multilayer circuit board 1 The risk of bending damage of the circuit board 1 can be significantly reduced.

(2) The metal wiring portions arranged in multiple layers are formed by patterning with the same shape.
Thereby, the additional burden of the material and process concerning implementation of invention of (1) can be made very small. Therefore, the invention of (1) can be implemented in a preferable aspect in terms of economy.

(3) The relative area with respect to the area of the support substrate of each metal wiring part was made into the area more than fixed.
Thereby, the request | requirement of the heat dissipation improvement of the LED dot matrix display apparatus 10 accompanying the enlargement of a LED display apparatus, the densification of LED element arrangement | positioning, etc. can fully be responded.

(4) The support substrate 111 is made of a single resin film having a diagonal length of 65 inches or more.
As a result, the inventions (1) to (3) can be applied to large flexible multilayer circuit boards that have a large risk of bending, particularly in the manufacturing process.

(5) It was set as the LED dot matrix display apparatus formed by mounting an LED element on the flexible multilayer circuit board in any one of (1) to (4).
As a result, in the 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, it has excellent economic efficiency while enjoying the effects of the inventions (1) to (5). The LED dot matrix display device 10 can be manufactured under productivity.

  As described above, according to the present invention, the risk of bending damage of the substrate caused by the flexibility of the support substrate and the difference in flexural modulus between the support substrate and the metal wiring portion in the flexible multilayer circuit board. Can be reduced.

DESCRIPTION OF SYMBOLS 1 Flexible multilayer circuit board 111 Support substrate 112 Insulating protective film 121 Metal wiring part on the light emitting surface side 122 Metal wiring part on the back side 123, 124 Conductive plate part 123X, 123Y Insulating slit part on the light emitting surface side 124X, 124Y Insulation on the back side Slit part 131 Adhesive layer 132 Adhesive layer 133 Adhesive layer 14 Black layer for contrast enhancement 15 Through hole 151 Conductive material 16 Solder layer 2 LED element 10 LED dot matrix display device

Claims (5)

A flexible multilayer circuit board for LED elements,
A flexible support substrate;
A metal wiring portion horizontally disposed at a plurality of vertical positions including at least one outermost surface and the other outermost surface of the support substrate,
Each of the metal wiring portions is formed by a plurality of conductive plate portions,
An insulating slit portion which is a non-conductive portion between the conductive plate portions constituting one metal wiring portion, and an insulating slit portion which is a non-conductive portion between the conductive plate portions constituting another metal wiring portion A flexible multilayer circuit board arranged so as to have a positional relationship that satisfies the following condition (A) or (B).
(A) In an arbitrary group selected from among insulating slit portions that are parallel to each other and at different vertical positions, at least one insulating slit portion is different from other insulating slit portions in plan view of the multilayer circuit board. It is arranged in a horizontal position that does not overlap.
(B) In the arbitrary group, one insulating slit portion forms an overlapping portion by being disposed at a horizontal position where a portion thereof overlaps with another insulating slit portion in plan view of the multilayer circuit board. And
In addition, the overlapping portion does not communicate with the overlapping portion in another adjacent insulating slit portion in a plan view of the multilayer circuit board.   The flexible multilayer circuit board according to claim 1, wherein the metal wiring portions are all formed by patterning having the same shape.   The flexible multilayer circuit board according to claim 1 or 2, wherein a surface area of the metal wiring portion is an area of 80% or more in an area ratio with respect to a surface area of the support substrate.   The flexible multilayer circuit board according to any one of claims 1 to 3, wherein the support substrate is made of a single resin film having a diagonal length of 65 inches or more.   An LED dot matrix display device comprising LED elements mounted on the flexible multilayer circuit board according to claim 1.

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