JP2009231584A - Method of manufacturing led substrate and the led substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an LED substrate simply and efficiently. <P>SOLUTION: The method of manufacturing the LED substrate includes the steps of: thermocompression-bonding a linear conductive material to a thermoplastic resin film; and loading at least two LEDs on the linear conductive material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an LED substrate, and an LED substrate manufactured by the method.

  Light-emitting devices such as light-emitting diodes (LEDs) have low power consumption and long life, and can be reduced in size and thickness. Therefore, it is used for mobile phones, electric boards, signals, and the like. Recently, in particular, it is expected to be used as a backlight for liquid crystal displays.

  That is, at present, cold cathode fluorescent lamps are mainly used as backlights for liquid crystal displays. However, in recent years, LEDs are in a position that can replace cold cathode fluorescent lamps due to thinning, energy saving, and high functionality of liquid crystal displays. In some cases, LEDs are already used as backlights.

  Conventionally, a substrate on which an LED is mounted is manufactured by forming a metal layer on the surface of a glass epoxy substrate, etching the metal layer into a circuit, and soldering the LED on the circuit. However, since the glass epoxy substrate must be thick due to its structure, even if a heat dissipation layer is provided on the back surface of the circuit, sufficient heat dissipation cannot be ensured. Therefore, in order to improve heat dissipation, an LED substrate using a thin substrate has been studied.

  For example, in Patent Document 1, a metal foil layer is fixed to an insulating layer made of a thermosetting epoxy resin, a circuit for mounting an LED is formed, and further, an insulating layer and a heat dissipation substrate are fixed by insulating. A technique for reducing costs by providing layers only where necessary is disclosed.

  However, in the technique of Patent Document 1, a circuit is formed by etching and cannot be implemented efficiently and at low cost. That is, in the circuit forming process by etching, complicated processes such as degreasing and cleaning of the metal layer, formation of a resist photosensitive film, exposure, development, etching, and peeling are necessary. Also, the metal layer removed by etching is wasted. Therefore, when a circuit is formed by etching, the cost of etching reaches several times the cost of the substrate itself. Further, ferric chloride is generally used for etching, but waste liquid containing this cannot be easily discarded. Moreover, when bonding a heat sink to the insulating layer made of a thermosetting resin, a thermosetting adhesive must be used. Therefore, time and equipment and a lot of energy are required for heating and pressurization for thermosetting, and there is a situation that it is difficult to reduce the cost. In addition, the substrate becomes thicker by the amount of the adhesive layer, and there is a demerit that the thermal conductivity is lowered by the adhesive.

On the other hand, Patent Document 2 discloses a technique for manufacturing a flexible parallel line by integrally covering a plurality of conductive wires rolled into a flat plate shape with a flexible insulating resin. However, such parallel lines are for connecting between boards or circuits, not for mounting a device. Actually, the parallel lines are covered by dipping the insulating resin, and it is not easy to mount the device by exposing the parallel lines except at the ends. Moreover, in patent document 2, the kind of insulating resin which coat | covers conducting wire is not specified.
JP 2007-220925 A JP 57-115714 A

  As described above, flexible LED substrates have been known. However, the manufacturing process is complicated, such as requiring etching, and it has never been easy to manufacture.

  Therefore, an object to be solved by the present invention is to provide a method for easily and efficiently manufacturing an LED substrate.

  The present inventor has intensively studied to solve the above problems. As a result, if a thermoplastic resin film such as a liquid crystal polymer film is used as the substrate and a linear circuit is thermocompression bonded to this substrate, the substrate can be used as a backlight for a liquid crystal display, etc. Has been found to be extremely simple and efficient, and the present invention has been completed.

  The method for manufacturing an LED substrate according to the present invention includes a step of thermocompression bonding a linear conductive material to a thermoplastic resin film; and a step of mounting at least two LEDs on the linear conductive material. To do. In addition, the aspect which mounts LED in a linear conductive material includes all the aspects which mount LED on a board | substrate by using a linear conductive material as a circuit. For example, a mode in which the body of a surface-mounted LED is disposed between a broken portion of one linear conductive material or between two linear conductive materials and each electrode is soldered to the linear conductive material; A mode is conceivable in which one wire-breaking end portion or one of the two wire-conducting materials in one wire-conductive material is die-bonded and wire-bonded to the other wire-breaking end portion or the other wire-conducting material.

  In the above method, it is preferable to press-fit the linear conductive material to the surface of the thermoplastic resin film when the linear conductive material is thermocompression bonded. For example, when a circuit is formed by etching or when a circuit is attached to a substrate with an adhesive, the circuit rises by the thickness of the substrate surface, and a smooth circuit cannot be obtained. As a result, as shown in FIG. 1, a space corresponding to the circuit thickness is generated between the substrate and the LED. As a result, particularly when a surface-mounted LED with a die heat sink is mounted, a high heat conductive adhesive such as solder or silver paste may enter the space and the electrode may be short-circuited. . Further, when the LED bare chip is sealed with a transparent resin, if there is a step between the circuit and the substrate as shown in FIG. 2, the resin may spread excessively along the circuit as shown in FIG. As a result, the formed product made of the transparent sealing resin is optically distorted, which may cause the light diffusion uniformity to be impaired, and may cause insufficient bare chip sealing. In this case, even if a dam material is used, the transparent resin may flow out of the space between the substrate and the dam material. However, if a linear conductive material to be a circuit is press-fitted to the surface of the thermoplastic resin film, a gap is hardly generated between the substrate and the surface mounted LED with the die / heat sink as shown in FIG. In addition, if there is no step between the linear conductive material and the thermoplastic resin film as shown in FIG. 5, excessive spreading of the sealing resin in the length direction of the linear conductive material can be suppressed as shown in FIG. The risk of optical distortion formation can be reduced.

  Further, if the substrate on which the circuit is provided is smooth, the accuracy is improved when printing cream solder, a resist agent, or the like. Further, as will be described later, in the LED substrate, a hole may be formed in order to improve heat dissipation or to disconnect the circuit. At this time, depending on the production method, it is efficient to form a hole by stacking multiple substrates, but if there is no step between the circuit surface and the substrate surface, the substrate will not be displaced easily when drilling, and stable drilling is possible. Become. In the case of a circuit board having a thermoplastic film as an insulating layer, it is also conceivable that after the copper foil on the film is etched to form a circuit, the circuit is pressed into the film by heating. However, in the present invention, since a simple linear conductive material is used as a circuit, the circuit can be pressed and pressed at the same time, which is very efficient.

  In the above method, in order to connect the LEDs mounted between the two linear conductive materials in series, a step of alternately disconnecting between the mounted LEDs or between the portions where the LEDs are to be mounted is performed. It is preferable to implement. As shown in FIG. 7, when a plurality of LEDs are connected in parallel, the brightness may be uneven due to individual differences of the LEDs. However, if a plurality of LEDs are connected in series, there is an advantage that uniform brightness can be obtained. In addition, when a plurality of LEDs are mounted between two linear conductive materials, a circuit that connects LEDs in series extremely easily is formed by alternately disconnecting the circuits between the LED mounting portions as shown in FIG. Is possible.

  Furthermore, it is preferable to carry out a step of thermocompression bonding at least three linear conductive materials and further connecting portions where LEDs are connected in series. If LEDs are connected in series as described above, uniform brightness can be obtained, but if even one LED is defective, all the LEDs connected in series will not light up. Therefore, if the LEDs connected in series are connected in parallel as shown in FIG. 9 and FIG. 10, even if some of the series LEDs are defective, the other series LEDs are turned on, so that the whole is not turned on. There is nothing. Such an array of LEDs can be easily formed by disconnection at the LED mounting portion.

  In the method of the present invention, as shown in FIG. 11, on the surface of the thermoplastic resin film on the side where the linear conductive material is thermocompression bonded, the portion other than the portion on which the LED is mounted or the portion other than the portion to be mounted is porous resin. It is preferable to perform the step of coating with a film. Conventionally, when an LED is mounted on a transparent or translucent substrate, in order to increase the light reflection efficiency, the substrate is mixed with titanium oxide or the like to reduce transparency or whiten. However, when a large amount of an inorganic substance such as titanium oxide is mixed, there is a problem that the strength of the substrate is lowered. On the other hand, if the reflectance is increased by covering the substrate with a porous resin film, the above-described problems of the prior art do not occur. Further, as described later, when the LED bare chip is sealed with a transparent resin, the porous resin film can be used as a dam material so that the transparent resin does not flow out of the necessary portion. Further, since the porous resin film is porous, it can diffuse light with extremely high efficiency. In addition, the porous resin film has an advantage that flexibility is not impaired even if it is bonded to a thermoplastic resin film.

  Furthermore, in the method of the present invention, when using an LED bare chip, it is preferable to include a step of sealing the LED with a transparent resin. In particular, when using an LED bare chip, sealing is important. In addition, when the circuit surface is covered with the porous resin film as described above, the concave volume of the porous resin film is slightly exceeded by selecting a porous film made of a resin having a low affinity with the sealing resin. Even if an amount of the sealing resin is injected, the sealing resin does not spread on the porous resin film, and has a convex lens shape as shown in FIG. The light extraction effect of such a convex lens-shaped sealing resin is high. Moreover, the light of a plane direction among the lights emitted from the LED bare chip causes irregular reflection on the side surface of the porous resin film. As a result, it becomes possible to use light that could not be used effectively.

  It is preferable to provide a heat-dissipating layer on the surface of the thermoplastic resin film on the side opposite to the thermocompression-bonded side or the side to be thermocompressed. In the LED substrate, it is important to reduce heat generated by light emission.

  Moreover, it is preferable to provide a through hole for heat dissipation in the thermoplastic resin film, the linear conductive material, and the heat dissipation layer. By providing such a through hole, it becomes possible to more efficiently release heat generated by light emission to the outside of the substrate. Such a through hole can also be used as a means for disconnecting the linear conductive material.

  The LED substrate of the present invention is manufactured by the above-described method of the present invention.

  According to the method of the present invention, a substrate on which a plurality of LEDs are mounted can be manufactured very easily and efficiently. More specifically, by using a thermoplastic resin film such as a liquid crystal polymer film as the insulating layer, it is possible to form a circuit only by attaching a linear conductive material by thermocompression bonding without etching. Therefore, the present invention is extremely useful industrially as a technique for easily and efficiently manufacturing an LED substrate having excellent characteristics, which has been increasing in demand in recent years.

  The method for producing an LED substrate according to the present invention includes a step of thermocompression bonding a linear conductive material in parallel or substantially in parallel to a thermoplastic resin film; and a step of mounting at least two LEDs on the linear conductive material; It is characterized by including. Hereinafter, the implementation conditions of the present invention will be described.

(1) Thermocompression bonding step of linear conductive material In the present invention, the linear conductive material is thermocompression bonded to the thermoplastic resin film in parallel or substantially in parallel.

  The thermoplastic resin constituting the insulating layer in the present invention can be widely selected according to the purpose of use as long as it has high resistance to heat required for thermocompression bonding of the linear conductive material, and is not particularly limited. For example, liquid crystal polymer, polyether ether ketone, polyether sulfone, polyether imide, polyamide, polyamide imide, polyarylate, polyphenylene sulfide, polyethylene naphthalate, mixed resin of two or more of these, and these resins as main components The polymer alloy etc. which are included as can be used. Here, the “main component” means containing 50% by mass or more, preferably 70% by mass or more, and more preferably containing 80% by mass or more with respect to the polymer alloy.

  As the thermoplastic resin constituting the insulating layer, a liquid crystal polymer is suitable. The liquid crystal polymer is excellent in heat resistance and has high resistance not only to heat generated from the LED but also to heat required for thermocompression bonding of the linear conductive material. In addition, a liquid crystal polymer having a linear expansion coefficient close to that of a metal constituting the linear conductive material, for example, copper, which is often used as a typical conductive material, is also sold. Stress can be reduced.

  The liquid crystal polymer is a heat-resistant thermoplastic resin, and includes a thermotropic liquid crystal polymer exhibiting liquid crystallinity in a molten state and a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state. The liquid crystal polymer used in the present invention is preferably a thermotropic liquid crystal polymer, more specifically, a thermotropic liquid crystal polyester or a thermotropic liquid crystal polyester amide.

  The thickness of the thermoplastic resin film used as the insulating layer in the present invention is preferably about 10 μm or more and 2000 μm or less. If it is too thin, the strength may be insufficient, while if it is too thick, it may be difficult to form a film. In addition, what is necessary is just to determine suitably the planar shape and magnitude | size of a thermoplastic resin film according to the magnitude | size of the apparatus etc. which apply the completed LED board.

  In the liquid crystal polymer film, the linear expansion coefficient can be adjusted. Such a linear expansion coefficient is preferably adjusted to 30 ppm / ° C. or less in a direction parallel to the film plane. More preferably, it is 25 ppm / ° C. or less. The linear expansion coefficient of the liquid crystal polymer film can be adjusted by controlling the molecular orientation. Moreover, you may adjust by addition of a filler. However, since the filler may adversely affect the surface smoothness of the liquid crystal polymer film, the linear expansion coefficient is preferably adjusted according to the stretching conditions.

  When mounting a surface mounted LED with a die heat sink, it is preferable to make a hole in the thermoplastic resin film in order to join the die heat sink and the heat dissipation layer with a heat conductive adhesive. What is necessary is just to adjust the magnitude | size of this hole according to the magnitude | size of LED.

  In the present invention, the material of the linear conductive material to be thermocompression bonded to the thermoplastic resin film is not particularly limited as long as it is used for the circuit of the circuit board. For example, copper, silver, gold, aluminum, iron, nickel, alloys containing these, and conductive carbon materials such as carbon fibers can be exemplified, and are preferably widely used as electronic circuit materials. Copper or copper alloy is used. Further, the linear conductive material may be metal-plated either before or after being bonded to the thermoplastic resin film.

  The linear conductive material has a circuit role in the LED substrate of the present invention. Therefore, although a wire having a diameter of about 20 μm or more and about 5 mm or less may be used, it is preferably formed in a flat plate shape for easy mounting of the LED. Moreover, the line which made the mounting part of LED flat form may be sufficient. For example, it is preferable that the cross-sectional shape is a linear metal foil having a width of 0.05 to 50 mm and a thickness of about 1 to 500 μm.

  In the present invention, the linear conductive material is thermocompression bonded to the thermoplastic resin film. The number of linear conductive materials to be thermocompression bonded is not particularly limited, but is preferably two or more. With only one, a plurality of LEDs must be connected in series, and cannot be connected in parallel. Further, if two linear conductive materials are used, LEDs can be connected in parallel, and can be connected in series as will be described later. If three or more linear conductive materials are used, LED groups partially connected in series can be further connected in parallel. As a result, each LED connected in series can emit light almost evenly regardless of its quality, and in addition, when connected in parallel, some of the LEDs have a defective series part including the LEDs. Ceases to emit light, but the other series portions can emit light, so that the overall light emission amount is reduced, but the risk of total extinction can be reduced.

  When two or more linear conductive materials are thermocompression bonded, they are preferably arranged in parallel or substantially parallel to each other. In some cases, an LED may be mounted between two linear conductive materials. In that case, if the spacing between the conductive materials on the line is not uniform, it may be difficult to automate the manufacturing, and the LED cannot be mounted. There may be cases. When two or more linear conductive materials are thermocompression bonded, the distance between the linear conductive materials depends on the type and size of the LED to be mounted, but is usually about 10 μm or more and 50 mm or less, more preferably 20 μm. More than 5mm.

  Note that two or more linear conductive materials may be formed by sticking one linear conductive material having a relatively wide width and then cutting the central portion into a straight line.

  The conditions for thermocompression bonding the linear conductive material to the liquid crystal polymer film may be appropriately determined by a preliminary experiment or the like. For example, a linear conductive material to be thermocompression-bonded is disposed on a liquid crystal polymer film, and a release sheet such as a porous PTFE sheet is inserted above and below it, temperature: 200 to 400 ° C., pressure: 0.5 to 10 MPa, Thermocompression bonding time: Thermocompression bonding in 3 seconds to 5 minutes. In general, it can be seen that the method of the present invention is advantageous in terms of speed and energy and equipment restraint time as compared with the case where heating for several hours is required for curing the thermosetting resin.

  When thermocompression bonding the linear conductive material, it is preferable to press-fit the linear conductive material to the surface of the thermoplastic resin film. If there is no step between the linear conductive material and the thermoplastic resin film, as shown in FIGS. 4 to 6, when soldering the surface mounted LED with die / heat sink, or when sealing the LED bare chip Excessive spread of the resin can be more reliably suppressed. Moreover, if the board | substrate which provided the circuit is smooth, when printing cream solder, a resist agent, etc., the precision will improve. In order to press-fit the linear conductive material to the surface of the thermoplastic resin film, the thermocompression bonding conditions may be adjusted. For example, the temperature and pressure at the time of thermocompression bonding may be increased to extend the thermocompression bonding time.

  In the present invention, a linear conductive material can be thermocompression bonded to both surfaces of a thermoplastic resin film, and the circuits on both surfaces can be joined by a through hole or a conductive bonding method.

(2) Disconnection process of linear conductive material In this invention, the linear conductive material thermocompression-bonded to the thermoplastic resin film is disconnected as needed. For example, as shown in FIG. 7, when LEDs are mounted in parallel between two linear conductive materials, it is not necessary to disconnect the linear conductive material. However, when mounting a plurality of LEDs in series on a single linear conductive material, it is necessary to disconnect the portion where the LEDs are to be mounted.

  Moreover, as shown in FIG. 8, in order to mount a plurality of LEDs between two linear conductive materials and connect the LEDs in series, the portions where the LEDs are to be mounted are alternately disconnected. Good.

  When at least three linear conductive materials are thermocompression-bonded, a portion where LEDs are connected in series may be further connected in parallel as necessary. That is, when a plurality of LEDs are mounted in series on one linear conductive material, the linear conductive material is appropriately disconnected between the LEDs or between the portions where the LEDs are to be mounted, and both ends are disconnected. What is necessary is just to couple | bond this part with the two linear electrically-conductive materials arrange | positioned so that it may be pinched | interposed. In addition, when an LED is mounted in series between two linear conductive materials, as shown in FIGS. 9 and 10, the two linear conductive materials are connected between the LED and the disconnected portion. What is necessary is just to combine with two linear electrically-conductive materials arrange | positioned so that it may pinch | interpose.

  The disconnection of the linear conductive material needs to be adjusted to some extent to the size of the LED when the LED is mounted in that place. On the other hand, in the case where the LED is not mounted at the disconnection location, the size of the disconnection portion is not particularly limited. For example, the disconnection and the heat radiation hole may be formed at the same time by a method such as punching out or cutting out the thermoplastic resin film together with the linear conductive material, and in addition to these, the heat radiation layer.

  In order to connect a plurality of linear conductive materials, in addition to using LEDs, other devices such as resistors may be used as needed, or simple electric wires may be used.

  The disconnection of the linear conductive material may be performed before mounting the LED or after mounting. The disconnection of the linear conductive material may be performed before the heat dissipation layer is provided, or may be performed after the heat dissipation layer is formed.

  As described above, if linear conductive materials are thermocompression bonded in parallel, it is possible to easily manufacture an LED substrate in series or parallel, or in combination of series and parallel.

(3) Formation process of heat dissipation layer It is preferable to provide a heat dissipation layer on the side opposite to the side where the linear conductive material of the thermoplastic resin film is subjected to thermocompression bonding or the side to be thermocompression bonded. In the LED substrate, it is important to reduce heat generated by light emission.

  The material for forming the heat-dissipating layer is not particularly limited as long as it has excellent thermal conductivity. For example, copper, silver, gold, aluminum, iron, nickel, cobalt, and alloys containing them, and further zinc are used. In addition to the above, ceramics such as alumina can be used.

  The thickness of the heat dissipation layer is not particularly limited, but can be, for example, about 5 μm or more. If the heat dissipation layer is too thin, the film strength may be reduced and the bonding operation may be difficult. On the other hand, the upper limit of the thickness is not particularly limited. Moreover, although a heat-radiating layer can also be formed only in the part which mounts LED, or the other side of the part which should be mounted, since a process becomes complicated, it is preferable to form in the whole back surface of a thermoplastic resin film. Further, if necessary, a heat dissipation layer can be bonded to a portion of the LED mounting surface that does not hinder light extraction, and the heat dissipation layer may be made larger than the thermoplastic resin film.

  The heat dissipation layer may be attached to the thermoplastic resin film using an adhesive. However, there are disadvantages that the heat dissipation effect is reduced by the thickness of the adhesive, and that application and drying of the adhesive are required. Therefore, it is preferable that the heat radiation layer is thermocompression-bonded taking advantage of the properties of the thermoplastic film. In addition, the thermocompression bonding conditions of the heat dissipation layer can be the same as the thermocompression bonding conditions of the linear conductive material.

  The heat dissipation layer may be formed before thermocompression bonding of the linear conductive material, or may be formed after thermocompression bonding. Or you may carry out simultaneously with the thermocompression bonding of a linear electrically-conductive material. However, from the viewpoint of protecting the LED, it is preferable to form a heat dissipation layer at least before mounting the LED.

  If the heat dissipation layer cannot secure a sufficient area for heat dissipation due to design reasons, the heat dissipation layer bonded to the thermoplastic film is used as the primary heat dissipation layer, which is further used as another heat dissipation member. By combining them, it is possible to supplement the heat dissipation capability. For example, if the heat dissipation fin is bonded to the primary heat dissipation layer, or if it is a device with LED, the entire device with LED is used as a heat dissipation material by combining a component with good thermal conductivity to the primary heat dissipation layer. Techniques can be used.

(4) LED mounting step In the present invention, at least two LEDs are mounted. A complicated process is not required only by mounting one LED on a circuit, but the present invention aims to easily and efficiently manufacture a substrate on which a plurality of LEDs are mounted.

  A conventionally known method may be used for mounting the LED. That is, in the case of a surface mount type LED with a die heat sink, the die heat sink is positioned in a hole provided in the thermoplastic resin film, and the heat radiation layer on the back surface and the die heat sink are joined by a highly heat conductive material such as solder, Each electrode is soldered to a linear conductive material. In the case of the LED bare chip, for example, the chip is die-bonded to one of the two linear conductive materials, and the chip and the other linear conductive material are wire-bonded with a gold wire or the like. However, the direction in which the LED is mounted is selected according to the purpose.

(5) Insulating step In the present invention, after the linear conductive material is thermocompression bonded to the thermoplastic resin and the LED is mounted, it is preferable to insulate the circuit surface from the outside. Such insulation can be performed by applying a general insulating paint or a highly light-reflective protective resist. Of course, other generally known insulation methods can also be used. Further, a thermoplastic resin film may be further thermocompression bonded to the circuit surface.

(6) Formation Step of Light Reflecting Layer In the present invention, it is preferable to form the light reflecting layer on the outermost surface of the thermoplastic resin film on the side where the linear conductive material is thermocompression bonded. Some thermoplastic resin films have low light transmittance, but are generally transparent or translucent. Therefore, although the light emitted from the LED reflects to some extent, a part of the light is transmitted or absorbed by the thermoplastic resin film. However, if the light reflecting layer is formed, the light emitted from the LED can be used effectively.

  The means for forming the light reflecting layer is not particularly limited, and a conventional technique may be applied. However, it is preferably performed by covering a portion other than the portion where the LED is mounted or a portion other than the portion where the LED is mounted with a porous resin film. If it coat | covers with a porous resin film, it will become possible to diffusely reflect light effectively. In addition, the resin film has an advantage of being lightweight and flexible.

  Examples of the material for the porous resin film include PTFE (polytetrafluoroethylene), PET (polyethylene terephthalate), and PP (polypropylene). The pore diameter of the porous resin film is not particularly limited, but can be about 10 μm or less in terms of an average value of the diameters. As the light reflecting layer of the present invention, a porous PTFE film is particularly suitable. PTFE exhibits excellent light resistance and is also resistant to light degradation.

  The porous PTFE to be coated can be produced by forming a PTFE powder into a sheet and further stretching it in a uniaxial direction or biaxial direction to make it porous. Moreover, since there exists what is marketed as a light reflection material, a porous PET film and porous PP film should just be used.

  The thickness of the porous resin film may be adjusted as appropriate, but is preferably about 10 μm or more and 2000 μm or less. If the thickness is less than 10 μm, the light reflection efficiency may be reduced, while if it exceeds 2000 μm, the cost may increase.

  The means for coating with a porous resin film is not particularly limited, and conventional techniques can be used. For example, since some porous resin films are difficult to adhere to a thermoplastic resin film only by thermocompression bonding, an adhesive composed of an epoxy resin, a phenol resin, a polyimide resin, or a BT resin is used to form a thermoplastic resin film. Just paste. Moreover, it is also possible to stick using an adhesive. In addition, an adhesive sheet obtained by impregnating the above adhesive with a porous resin film may be used to bond the porous resin film serving as the reflective layer and the thermoplastic resin film. As such a light reflective film with an adhesive, there are commercially available films such as FLEXIBOND white light reflective film manufactured by Japan Gore-Tex. If such a film with an adhesive is used, the porous resin film and the thermoplastic resin film can be easily bonded.

  The light reflecting layer can be formed without particular limitation as long as it is after thermocompression bonding of the linear conductive material. If the light reflecting layer is formed before the heat radiating hole is formed, it is difficult to form the heat radiating hole except for the light reflecting layer, and if the heat radiating hole is provided up to the reflecting layer, the reflection efficiency may be lowered. is there. However, in order to increase the heat dissipation efficiency, a heat dissipation hole may be actively formed in the reflective layer.

(7) Step of forming heat radiating through hole In the LED substrate of the present invention, it is preferable to provide a heat radiating through hole in the thermoplastic resin film, the linear conductive material and the heat radiating layer. The LED emits heat by light emission, and the light emission function is reduced by the heat. In recent years, higher brightness and higher power of LEDs have progressed further, and the heat dissipation of LED substrates has become important. It is also desirable to increase the heat dissipation efficiency in order to extend the life of the substrate.

  It is preferable that the hole for heat dissipation penetrates the thermoplastic resin film, the linear conductive material, and the heat dissipation layer. This is to improve the air permeability and dissipate the heat generated by the heat generation of the LED to the outside. Moreover, in order to dissipate the heat from LED efficiently, the position of the hole is preferably provided in the vicinity of the LED.

  In the case of a surface mount type LED with a die heat sink, it is preferable to make a hole only in the thermoplastic resin film and join the die heat sink and the heat dissipation layer with a high thermal conductivity material. By this aspect, the heat dissipation efficiency is further increased.

  The size and shape of the heat radiating through hole are not particularly limited, but are preferably 50 μm or more and 50 mm or less in terms of diameter. However, the number and size of the through holes need to be adjusted as appropriate. If the number of through holes is too large or too large, not only will the substrate strength be reduced, but the heat dissipation effect may be reduced, so the size, number, and position of the through holes in consideration of the type and number of LEDs. Etc. Moreover, when the heat radiating hole also serves as a disconnection means for the linear conductive material, the size of the heat radiating hole needs to be equal to or larger than the width of the linear conductive material. On the other hand, in the case where the heat radiating hole is provided at a place other than the disconnection portion of the linear conductive material, the size of the heat radiating hole must be set to such a degree that there is no fear of disconnection.

(8) LED sealing process When an LED bare chip is used, it is preferably sealed with a transparent resin after being mounted on a linear conductive material. Sealing is important when using LED bare chips.

  The LED sealing means is not particularly limited, and a conventional technique may be applied. For example, as the sealing resin, a transparent or translucent liquid sealing resin made of an epoxy resin or a silicon resin can be appropriately selected and used.

  Conventionally, when a flat substrate is sealed with a liquid resin, the spread of the resin from the sealing portion has been suppressed by adjusting the viscosity or thixotropic property of the resin or using a dam material. However, when the viscosity of the resin is increased, sealing work becomes difficult, for example, bubbles are likely to remain in the sealing resin. Even when a dam material is used, the viscosity of the transparent resin may decrease during heat curing, and the resin may flow out of the step between the substrate and the circuit. Therefore, in the present invention, it is preferable to press-fit the linear conductive material to the surface of the thermoplastic resin film. By eliminating the step between the linear conductive material and the thermoplastic resin film, excessive spreading of the sealing resin can be suppressed (see FIGS. 3 and 6).

  Moreover, it is preferable to use a porous resin film coated as a reflective layer as it is as a dam material. Since the porous resin film has an excellent light reflectance, the luminous efficiency of the LED substrate according to the present invention is increased. Further, by selecting a porous resin film that has a low affinity with the sealing resin and repels the sealing resin, it becomes possible to obtain a convex lens-like transparent resin shape as shown in FIG. In addition, it is also possible to form shapes other than a convex lens shape according to the objective by adjusting the height of a dam material and the amount of sealing resin.

  Usually, when an LED substrate is manufactured, since the LED is separately manufactured and then mounted on a circuit, the efficiency is relatively low. However, when the LED bare chip is mounted in the present invention, the LED bare chip can be directly die-bonded on the linear conductive material, and then the LED can be sealed after wire bonding. That is, according to the present invention, an LED substrate can be continuously produced efficiently by a series of operations from circuit formation to LED mounting.

  According to the method of the present invention, a substrate on which a plurality of LEDs are arranged can be easily and continuously manufactured without an etching step. At present, the reason why LED lighting and LED backlights cannot be widely used is due to the high manufacturing cost of the substrate. On the other hand, according to the present invention, for example, a roll-shaped conductive wire can be continuously bonded to a roll-shaped liquid crystal polymer film without an etching step, and a product LED circuit board can be obtained in a roll-shape. It becomes possible. Such an embodiment is generally referred to as a roll-to-roll, and is a continuous production method suitable for mass production that can greatly reduce production costs due to high efficiency. Of course, even when roll-to-roll is not applied to the method of the present invention, the method of the present invention is sufficiently efficient and low cost. Therefore, it is considered that the present invention can contribute to the widespread use of LEDs which are excellent in luminous efficiency and have a long life and are environmentally friendly light sources.

  Moreover, the LED board manufactured by the preferable aspect of this invention method is excellent in luminous efficiency and heat dissipation efficiency, and is high-intensity and long life. Therefore, the LED substrate according to the present invention is a backlight for a liquid crystal display, a panel backlight used for advertising, etc., house lighting, various types of lighting in automobiles, equipment lighting, light sources for amusement devices, aircraft, space development and railway related lighting. It can be expected to be widely used for sign boards and street lamps.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

Example 1 Production of LED substrate according to the present invention (1) Thermocompression bonding of linear conductive material On a liquid crystal polymer film (product name “BIAC BC060W-NT” manufactured by Japan Gore-Tex Co., Ltd.) having a thickness of 25 mm × 300 mm and a thickness of 60 μm Two linear copper foils having a width of 2 mm and a thickness of 18 μm (manufactured by Furukawa Circuit Foil, product name “GTS-MP-18”) were arranged in parallel at intervals of 4 mm. A porous PTFE sheet is placed above and below it as a release sheet, and heated using a small vacuum press (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 300 ° C. and a pressure of 1 Mpa for 3 minutes. Press fit to the surface of the film. The liquid crystal polymer film obtained by thermocompression bonding the linear copper foil was taken out after cooling.

  Nine holes having a width of 2.5 mm and a length of 6 mm were formed at intervals of 30 mm between the two linear copper foils.

(2) Formation of heat dissipation layer A hot-dip galvanized steel sheet having a thickness of 1.2 mm was thermocompression bonded over the entire back side of the liquid crystal polymer film in the same manner as in the above condition (1).

(3) Mounting of LED The anode and cathode of the white chip type LED (product name “NS6W083AT”) manufactured by Nichia Chemical Co., Ltd. are positioned so that the die / heat sink is placed in the hole formed in (1) above. Soldering was performed on each linear copper foil, and soldering was performed through a film hole in which a hot-dip galvanized steel sheet and a die heat sink, which were heat release layers, were previously opened.

(4) Insulation Environmental insulation was performed by applying an insulating paint for printed circuit boards (product name “BC1000” manufactured by Nippon Soda Co., Ltd.) to the exposed and soldered portions of the linear copper foil.

  As a result, it was confirmed that a continuous LED substrate having a light weight and extremely good heat dissipation can be obtained with high productivity without an etching process.

Example 2 Production of LED Substrate According to the Present Invention (1) Thermocompression Bonding of Linear Conductive Material Liquid Crystalline Polymer Film 10 mm Width × 120 mm Length and 60 μm Thickness (“BIAC BC060W-NT” manufactured by Japan Gore-Tex Co., Ltd.) Two linear copper foils (manufactured by Furukawa Circuit Foil, “GTS-MP-18”) having a width of 1.0 mm and a thickness of 18 μm were arranged in parallel at an interval of 100 μm. Porous PTFE is disposed above and below it as a release sheet, and heated using a small vacuum press machine (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 300 ° C. and a pressure of 1 Mpa for 3 minutes. It was press-fitted to the surface and taken out after cooling. The surface of the linear copper foil was further subjected to electrolytic silver plating with a thickness of 1 μm.

(2) Formation of heat dissipation layer In a film similar to the liquid crystal polymer film of (1) above, holes having a diameter of 3 mm at intervals of 30 mm as positions where LED bare chips are to be mounted at positions corresponding to the two linear copper foils. Was opened in three places. The liquid crystal polymer film is overlaid on the surface of the above-mentioned (1) linear copper foil, and an aluminum plate having the same size of 3 mm is further laminated on the back surface, and heated and pressurized under the same conditions as in (1) above. It stuck together at once.

(3) Light-reflective layer / dam material In the porous PTFE sheet with adhesive layer (Japan Gore-Tex, FLEXIBOND white light-reflective film), a hole with a diameter of 3 mm is made at the position corresponding to the LED mounting location, and this hole is lined The film of the above (2) was bonded to the hole on the copper foil.

(4) Mounting LED On one of the two linear copper foils located in the hole of the porous PTFE sheet, an LED bare chip (CREE, C527-MB-290) is silver paste one by one in each hole. Die bonding was performed, and wire bonding was performed from each bare chip onto the other linear copper foil with a gold wire.

(5) LED sealing Transparent epoxy resin (manufactured by Inabata Sangyo Co., Ltd., “main agent: HL2000A, curing agent: HL2000B2”) slightly rises from the surface of the porous PTFE sheet in the hole of the porous PTFE sheet on which the LED bare chip is mounted. And kept at a horizontal level at 120 ° C. for 60 minutes and then at 150 ° C. for 4 hours. The resulting sealing shape was a convex lens with a good balance.

  As described above, an LED substrate in which LEDs are mounted in parallel at intervals of 30 mm on a belt-like circuit board having a width of 10 mm, a heat dissipation layer is formed on the back surface, and sealed with a convex lens-like transparent resin was easily manufactured.

Example 3 Production of LED substrate according to the present invention (1) Thermocompression bonding of linear conductive material On a liquid crystal polymer film (product name “BIAC BC060W-NT” manufactured by Japan Gore-Tex Co., Ltd.) having a thickness of 25 mm × 300 mm and a thickness of 60 μm Two linear copper foils having a width of 1.0 mm and a thickness of 18 μm were arranged in parallel at intervals of 1.0 mm. Porous PTFE was placed as a release sheet above and below it, and was heated under pressure at a temperature of 300 ° C. and a pressure of 1 Mpa for 1 minute using a small vacuum press (manufactured by Imoto Seisakusho), and the linear copper foil was thermocompression bonded. The liquid crystal polymer film was taken out after cooling to room temperature.

(2) Formation of serial structure Two linear copper foils were disconnected by opening holes with a diameter of 1.1 mm together with the substrate at intervals of 60 mm. The disconnection positions of the two linear copper foils were shifted from each other by 30 mm.

(3) Mounting LED As with the circuit diagram shown in FIG. 8, a surface mount type LED element (Nichia Corporation) is connected in series so that the parallel line circuit disconnected by the hole formed in (2) above is connected in series. The product name "NSSR426CT" manufactured by the company was soldered. The direction of the LED was assumed to be arranged in series.

(4) Insulation Insulation was performed by applying an insulating paint for printed circuit boards (product name “BC1000” manufactured by Nippon Soda Co., Ltd.) to the exposed and soldered portions of the linear copper foil.

  As a result, a lightweight and flexible continuous tape-shaped LED substrate could be obtained without an etching step. From this result, according to the method of the present invention, it is considered that a roll-shaped LED substrate can be continuously and efficiently produced from a roll-shaped thermoplastic resin film.

It is a schematic diagram which shows the case where surface mount type LED with a die heat sink is mounted in the board | substrate which did not press-fit a linear electrically conductive material to the surface of a thermoplastic resin film. It is a schematic diagram which shows the case where an LED bare chip is mounted in the board | substrate which did not press-fit a linear electrically conductive material to the surface of a thermoplastic resin film. FIG. 3 is a schematic diagram of a cross section of a portion where resin spreads along the linear conductive material of the LED substrate in the length direction of the linear conductive material when FIG. 2 is rotated by 90 °. It is a schematic diagram which shows the case where surface mount type LED with a die heat sink is mounted in the board | substrate which press-fitted the linear electrically conductive material to the surface of the thermoplastic resin film. It is a schematic diagram which shows the case where a LED bare chip is mounted in the board | substrate which press-fits the linear electrically conductive material to the surface of the thermoplastic resin film. FIG. 6 is a schematic view of a cross section of the LED substrate when FIG. 5 is rotated by 90 °, that is, in the length direction of the linear conductive material. It is a figure of the circuit which connected LED in parallel between two linear electrically-conductive materials. It is a figure of the circuit which connected LED in series between two linear electrically-conductive materials. It is a figure of the circuit which connected the LED group connected further in series using four linear electrically-conductive materials. It is a bird's-eye view of the LED board which has the circuit which connected the LED group further connected in series using four linear electrically-conductive materials. It is a schematic diagram which shows the board | substrate which mounted LED bare chip | tip in parallel 3 rows, coat | covered the other than that part with the porous resin film, and sealed the LED bare chip | tip.

Explanation of symbols

  1: Thermoplastic resin film, 2: Linear conductive material, 3: LED with die heat sink, 4: Die heat sink, 5: High heat conductive adhesive, 6: Electrode, 7: Heat dissipation layer, 8: Substrate and LED 9: LED bare chip, 10: wire, 11: sealing resin, 12: LED, 13: disconnection point of linear conductive material, 14: resistor, 15: porous PTFE sheet

Claims (9)

A step of thermocompression bonding a linear conductive material to the thermoplastic resin film; and a step of mounting at least two LEDs on the linear conductive material;
The manufacturing method of the LED board characterized by including.   The manufacturing method of Claim 1 which press-fits a linear electrically conductive material to the surface of a thermoplastic resin film when thermocompression bonding a linear electrically conductive material.   3. The method according to claim 1, further comprising a step of alternately disconnecting between the mounted LEDs or between the portions where the LEDs are to be mounted in order to connect the LEDs mounted between the two linear conductive materials in series. The manufacturing method as described.   The manufacturing method in any one of Claims 1-3 including the process of thermocompression-bonding at least 3 linear electrically-conductive material, and further connecting the part which connected LED in series further in parallel.   5. The method according to claim 1, further comprising a step of covering the surface of the thermoplastic resin film on the side subjected to thermocompression bonding with a porous resin film other than a portion on which the LED is mounted or a portion to be mounted. The manufacturing method as described in.   The manufacturing method in any one of Claims 1-5 including the process of sealing the said LED bare chip with transparent resin, when an LED bare chip is used.   The manufacturing method in any one of Claims 1-6 including the process of providing a thermal radiation layer in the surface on the opposite side to the side which thermocompression-bonded the linear electrically conductive material of a thermoplastic resin film, or the side which should be thermocompression bonded.   The manufacturing method of Claim 7 including the process of providing the through-hole for heat dissipation in a thermoplastic resin film, a linear electrically conductive material, and a thermal radiation layer.   An LED substrate manufactured by the manufacturing method according to claim 1.