JP2007329369A - Light-emitting device, and method of manufacturing light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device equipped with a plurality of flip-chip light-emitting diodes on a ceramic substrate having a conductive film formed thereon. <P>SOLUTION: This light-emitting device consists of a plurality of flip-chip light-emitting diodes, a ceramic substrate, and a reflector. These elements are arranged so as to guide a light in a desired direction. A pair of electrodes for supplying power are provided on the lower portion of each of the flip-chip light-emitting diodes. The ceramic substrate is made of, e.g. alumina in which a silver-based conductive film is formed on a substantially overall surface of its top surface. A nickel thin film layer is formed on the silver-based conductive film, and a gold thin film layer is formed thereon and is connected to an electrode of each of the flip-chip light-emitting diodes. Further, of the flip-chip light-emitting diodes, at least a plurality of them are connected in series or in parallel to form a light-emitting device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device including a plurality of flip chip light emitting diodes on a ceramic substrate on which a conductive film is formed, and a method for manufacturing the light emitting device. In particular, the present invention relates to a light-emitting device and a light-emitting device that can supply power, dissipate heat, reflect light, and attach a reflector to a flip-chip light-emitting diode using a conductive film formed on a ceramic substrate. It is about the method. The present invention also relates to a light emitting device capable of emitting, for example, blue light, red light, green light, or white light by a plurality of flip chip light emitting diodes, and a method for manufacturing the light emitting device.

  The light emitting diode assembly and the backlight for the liquid crystal display panel in Japanese Patent Application No. 2004-217438 and Japanese Patent Application No. 2004-217439 proposed by the present applicant are formed on the electrode and submount of the flip chip type light emitting diode. This is to connect the existing wiring.

  FIG. 9 (a) is a conventional example, and is a schematic diagram for explaining a state where three flip chip type light emitting diodes of red, green and blue are attached to a submount, and (b) is also red, green, It is the schematic for demonstrating the state which attached the submount which attached the flip chip type light emitting diode which consists of three blue to the light emitting diode assembly board | substrate. In FIG. 9 (a), three-color flip chip light emitting diodes 911 (R), 912 (G), 913 (B) are connected to a common electrode 914 and the other electrodes 915, 916, 917, respectively. It is placed on the submount 94.

  In FIG. 9B, the three-color flip-chip light emitting diodes 911 (R), 912 (G), and 913 (B) include, for example, a pair of electrodes 914 and 915 at the bottom, and are formed from a semiconductor wafer. The submount 94 is cut out by dicing from the submount substrate. The submount substrate is continuous without dicing and can be used as a light emitting device. The submount 94 has a pair of wirings 95 formed on its upper surface by forming a vapor deposition pattern using etching or a mask. In the submount 94, for example, an insulating film is formed on a semiconductor wafer made of silicon, and a pair of wirings 95 is formed thereon.

The submount 94 is not particularly limited as long as it has excellent thermal conductivity and can form a wiring. For example, a submount 94 in which an insulating layer of an oxide film is formed on the surface of a silicon substrate is used. On the insulating film, a pair of wirings 95 is formed by forming a mask and depositing gold. As shown in FIG. 9B, the light emitting diode assembly substrate 98 has an opening 92 formed therein, and a connection electrode 90 provided in the vicinity of the opening 92 on the back surface. The flip chip type light emitting diode 91 is inserted into the opening 92 as shown in FIG. At that time, the connection electrode 90 is connected to a pair of wirings 95 of the submount 94 via a conductive thermosetting adhesive 97.
Japanese Patent Application No. 2004-217438 Japanese Patent Application No. 2004-217439

  The light emitting diode assembly and the liquid crystal display panel backlight in the conventional example are composed of a flip chip type light emitting diode, a submount, and a light emitting diode assembly substrate. When the flip chip type light emitting diode is used as a light emitting device, the submount and the light emitting diode assembling substrate have a problem that not only the size of the light emitting device is increased, but also wiring is troublesome. In addition, the light emitting device including the flip chip type light emitting diode has a problem that it is too large to be applied to a liquid crystal display panel which is miniaturized. The light emitting device in which a plurality of the flip chip type light emitting diodes are assembled has a problem of heat generation and a problem of irradiation efficiency.

  A light emitting device in which a plurality of flip chip type light emitting diodes are assembled includes forming a conductive film on the ceramic substrate, mounting a reflector on the ceramic substrate, mounting the conductive film and an electrode of the flip chip type light emitting diode, and the like. There was a problem that different properties had to be mounted on one ceramic substrate. Further, the flip chip type light emitting diode has a problem that when it tries to emit light brightly, the heat generation becomes large, and the mounting portion is peeled off due to the assembly process and the secular change during use. In the light emitting device, the conductive film is made of gold having high conductivity, and when the area is increased in order to improve heat dissipation, it becomes expensive. When cheap silver is used, the electrode of the flip chip type light emitting diode, and eutectic solder There is a problem that the adhesiveness is poor because is gold.

  In order to solve the above-described problems, the present invention provides a light-emitting device and a light-emitting device that have good light emission efficiency and good heat dissipation without the use of a submount and a light-emitting diode assembly substrate in the mounting of a flip-chip light-emitting diode. It aims to provide a method. It is an object of the present invention to provide a light-emitting device and a method for manufacturing the light-emitting device that are highly reliable even over time without peeling off the ceramic substrate, the reflector, the conductive film serving as the wiring, and the electrodes of the flip-chip light-emitting diode. Objective. An object of the present invention is to provide a light-emitting device and a method for manufacturing the light-emitting device that can efficiently connect a plurality of flip-chip light-emitting diodes and that can be easily used.

(First invention)
A light-emitting device according to a first aspect of the present invention is a ceramic substrate on which a wiring made of a conductive film for supplying electric power is connected to each electrode of a flip-chip type light emitting diode having a pair of electrodes, the ceramic substrate, And a reflector attached to the upper part of the wiring via an adhesive, and the wiring formed on the ceramic substrate of the package includes a silver-based conductive film and the silver-based A gold thin film layer of the wiring, comprising a nickel thin film layer provided on at least a portion where the flip chip type light emitting diode is disposed on an upper surface of the conductive film, and a gold thin film layer provided on the nickel thin film layer And an electrode of the flip chip type light emitting diode are connected by gold-tin eutectic solder.

(Second invention)
The light emitting device of the second invention is characterized in that the silver-based conductive film, the nickel thin film layer, and the gold thin film layer of the first invention are constituted by vapor deposition or plating.

(Third invention)
The light emitting device of the third invention is characterized in that the silver-based conductive film of the first invention or the second invention is silver or an alloy of silver and platinum and / or palladium.

(Fourth invention)
The light emitting device of the fourth invention is characterized in that the adhesive for connecting the reflectors of the first to third inventions is an inorganic adhesive.

(Fifth invention)
A light emitting device according to a fifth aspect is characterized in that a reflector of the first aspect through the fourth aspect is filled with a translucent silicone resin.

(Sixth invention)
A light emitting device according to a sixth aspect of the present invention is formed such that wirings connecting a plurality of flip chip type light emitting diodes arranged in the reflectors of the first to fifth aspects substantially cover at least the ceramic substrate inside the reflector. It is characterized by being.

(Seventh invention)
The light emitting device of the seventh invention is characterized in that the wiring provided on the ceramic substrate of the first to sixth inventions connects a plurality of flip chip type light emitting diodes in series.

(Eighth invention)
The light-emitting device according to the eighth aspect of the invention comprises two sets of three flip-chip type light-emitting diodes connected in series in the first to seventh aspects arranged in a regular hexagon to form a single assembly. It is arranged inside.

(9th invention)
A light emitting device according to a ninth aspect of the present invention includes two sets of flip chip type light emitting diodes of the first through seventh aspects connected in series, arranged in a square to form a single assembly, and the interior of the reflector. It is characterized by being arranged in.

(10th invention)
The light-emitting device according to the tenth aspect of the present invention includes four flip-chip light-emitting diodes according to the first to seventh aspects of the present invention connected in series, and is arranged in a square by making one pattern of wiring S-shaped. It is set as the aggregate | assembly and is arrange | positioned inside the said reflector, It is characterized by the above-mentioned.

(11th invention)
In the method for manufacturing a light-emitting device according to an eleventh aspect of the present invention, a wiring made of a conductive film for supplying power to each electrode of a flip-chip light emitting diode having a pair of electrodes is formed by forming a silver-based conductive film on a ceramic substrate. A nickel thin film layer is formed on at least a portion where the flip chip type light emitting diode is disposed on the upper surface of the silver-based conductive film, and a gold thin film layer is formed on the nickel thin film layer. An inorganic adhesive is applied between the upper portion of the wiring and the reflector, heated and bonded to manufacture a light emitting device package to which the reflector is attached, and then the gold thin film layer of the wiring and the flip chip type light emitting diode These electrodes are connected by gold-tin eutectic solder.

(Twelfth invention)
In the light emitting device manufacturing method according to the twelfth aspect, the silver-based conductive film, the nickel thin film layer, and the gold thin film layer are formed by vapor deposition or plating.

(13th invention)
In the method for manufacturing a light emitting device according to the thirteenth aspect, each package is formed in large numbers on a ceramic substrate, and the electrodes of the flip chip type light emitting diodes are connected to the wirings of the respective packages by gold-tin eutectic solder. The ceramic substrate is obtained by filling each reflector with a translucent silicone resin and then dividing the ceramic substrate.

(14th invention)
In the method for manufacturing a light-emitting device according to the fourteenth aspect of the present invention, a large number of each package is formed on a ceramic substrate, the ceramic substrate is half-cut by a laser, and the electrode of the flip-chip type light-emitting diode is formed on the wiring in each package. After connecting with gold-tin eutectic solder, each of the reflectors is filled with a translucent silicone resin, and then the ceramic substrate is divided.

(15th invention)
In the light emitting device manufacturing method according to the fifteenth aspect of the present invention, each package is a green sheet of a ceramic substrate, and a half-cut line is inserted at the time of press molding, and the electrode of the flip chip type light emitting diode is placed on the wiring in each package. Are connected to each other with gold-tin eutectic solder, and each of the reflectors is filled with a translucent silicone resin, and then the ceramic substrate is divided.

  According to the present invention, since the silver-based conductive film, the nickel thin-film layer, and the gold thin-film layer are formed on the ceramic substrate in this order by vapor deposition or plating, the silver-based conductive film that connects the electrodes of the flip-chip type light emitting diode is formed. And the gold thin film layer are compatible with each other, and a highly reliable connection can be made.

  According to the present invention, a light-emitting device using a flip-chip light-emitting diode that is easy to manufacture, reliable, and has a long lifetime without using a submount and a light-emitting diode assembly substrate and a method for manufacturing the light-emitting device are provided. I was able to get it.

  According to the present invention, the ceramic substrate on which the flip chip type light emitting diode is mounted has the conductive film formed on almost the entire surface, so that not only the heat is efficiently dissipated from the conductive film, but also the flip chip type light emission. The light from the diode can also be efficiently reflected together with the reflector. In addition, the conductive film can supply power to the flip-chip light emitting diode by a silver-based conductive film and can be attached with the reflector via a ceramic adhesive or the like, and can also be made of a thin gold film layer. It is cheaper than what you do.

  According to the present invention, for example, a phosphor film that absorbs light emitted from a flip-chip light emitting diode made of near-ultraviolet light can be efficiently converted into white light by forming blue, red, and green in this order. It is suitable for a backlight of a small light emitting device or a small liquid crystal display panel.

  According to the present invention, the connection between the electrode of the flip chip type light emitting diode and the conductive film is a eutectic solder, and the connection between the conductive film and the reflector is a ceramic adhesive whose melting point is higher than that of the eutectic solder. A highly reliable light-emitting device and a method for manufacturing the light-emitting device can be obtained.

(First invention)
The light emitting device according to the first aspect of the present invention includes at least a plurality of flip chip type light emitting diodes that emit near-ultraviolet light, a ceramic substrate, and a reflector, and is disposed so as to guide light in a desired direction. A pair of electrodes for supplying electric power is provided under each of the flip chip type light emitting diodes. The ceramic substrate is made of, for example, alumina, and a wiring made of a silver-based conductive film connected to the electrode of the flip chip type light emitting diode is formed on almost the entire surface. The reflector is attached to the top of the ceramic substrate and the wiring via a ceramic adhesive.

  The ceramic substrate, the reflector, and the wiring form a package. The electrode of the flip chip type light emitting diode is formed of the silver thin film conductive layer through a nickel thin film layer provided at least in a portion where the flip chip type light emitting diode is disposed, and a gold thin film layer provided on the nickel thin film layer. It is connected to the. That is, the nickel thin film layer and the gold thin film layer serve as counter electrodes constituting a part on the wiring side made of a silver-based conductive film.

  The nickel thin film layer is interposed between the silver-based conductive film layer and the gold thin film layer, thereby improving the adhesion between the two having poor compatibility. In addition, at least a plurality of the flip chip type light emitting diodes may be connected in series or in parallel to form one light emitting device. As the flip chip type light emitting diode of the present invention, for example, a light emitting diode emitting light having a wavelength of 320 μm to 650 μm was used. White light is obtained by passing light having a wavelength of 320 μm to 420 μm through a phosphor.

  The silver-based conductive film is formed on, for example, an alumina-based ceramic substrate by vapor deposition or plating, and for the heat dissipation and light reflection of the flip-chip light-emitting diode, the electrode of the flip-chip light-emitting diode It is formed almost all over. The reflector is mounted on the silver-based conductive film by, for example, firing a ceramic adhesive at 800 ° C., and a reflector for irradiating light of the flip chip light emitting diode in a predetermined direction is provided. It has been.

  The silver-based conductive film plays four roles of supplying power to the flip chip type light emitting diode, radiating heat from the flip chip type light emitting diode, reflecting light emitted from the flip chip type light emitting diode, and connecting part of the reflector. Can be achieved at the same time. In addition, a phosphor film that converts the near-ultraviolet light emitted from the flip chip type light emitting diode into blue, red, green, and white can be provided in the opening of the reflector.

  The gold thin film layer of the wiring and the electrode of the flip chip type light emitting diode are connected by heating gold-tin eutectic solder at, for example, 300 degrees C. Since the gold-tin eutectic solder melts at a temperature lower than the ceramic adhesive for mounting the reflector on the silver-based conductive film, it does not affect the mounting of the reflector.

(Second invention)
In the light emitting device of the second invention, the silver-based conductive film, the nickel thin film layer, and the gold thin film layer are formed by vapor deposition or plating. The silver conductive film, the nickel thin film layer, and the gold thin film layer are affected by the temperature at the time of attachment of the reflector or the attachment strength of the flip chip type light emitting diode. Therefore, the second invention is to connect the silver-based conductive film, the nickel thin film layer, and the gold thin film layer by vapor deposition or plating, etc., and eliminate the influence of temperature at the time of mounting. There is no fear of peeling inside. The silver-based conductive film has a nickel thin film layer interposed between it and the gold thin film layer, so that it has good adhesion and can be a wiring having excellent stability that does not peel off during assembly or aging.

(Third invention)
In the light emitting device of the third invention, the silver-based conductive film can be made of silver, an alloy of silver and platinum, an alloy of silver and palladium, and an alloy of silver, platinum and palladium.

(Fourth invention)
In the light emitting device of the fourth invention, the electrode of the flip chip type light emitting diode and the silver-based conductive film are connected by eutectic solder. The silver conductive film and the reflector are connected by an inorganic adhesive such as a ceramic adhesive or a glass adhesive. The eutectic solder is one having a melting temperature lower than that of the ceramic adhesive, so that the reflector, the silver conductive film, and the like are connected during the connection between the flip chip type light emitting diode and the silver conductive film. There is no such thing as the connection part of coming off.

(Fifth invention)
In the light emitting device according to the fifth aspect of the invention, the reflector is filled with a translucent silicone resin. Since the translucent silicone resin is filled in the reflector, the flip-chip light emitting diode, the silver-based conductive film, the fluorescent film, and the like can be protected at the same time.

(Sixth invention)
In the light emitting device of the sixth invention, a plurality of flip chip type light emitting diodes arranged inside the reflector are connected by wiring. In addition, since the wiring is formed so as to cover at least almost the entire surface of the ceramic substrate inside the reflector, not only the electric resistance is small, but also the heat dissipation of the flip chip type light emitting diode can be improved. .

(Seventh invention)
In the light emitting device of the seventh invention, a plurality of flip chip type light emitting diodes are connected in series by wiring provided on the ceramic substrate to constitute one aggregate. The flip chip type light emitting diodes connected in series can obtain one linear light emitting device by the series connection.

(Eighth invention)
In the light-emitting device according to the eighth aspect of the present invention, two sets of three flip-chip light-emitting diodes connected in series are arranged in a regular hexagon and are arranged as one aggregate inside the reflector. The aggregate is composed of a total of six flip-chip type light emitting diodes, and can emit large light as a surface light emitting device.

(9th invention)
In a light emitting device according to a ninth aspect of the present invention, two sets of two flip chip type light emitting diodes connected in series are arranged in a square to form one aggregate and are arranged inside the reflector. The aggregate has a total of four flip-chip light emitting diodes connected in series and parallel, and can emit a large amount of light as a point light source or a surface light source.

(10th invention)
A light-emitting device according to a tenth aspect of the present invention is that the four flip-chip type light-emitting diodes are connected in series and arranged in a square by making one pattern of wiring into an S-shape to form a single assembly of the reflector. Arranged inside. The assembly uses a S-shaped wiring pattern to connect a total of four flip-chip type light emitting diodes, so that the assembly can be used as a point light source or a surface light source even though they are connected in series. It was possible to irradiate a large light. By providing a plurality of aggregates according to the present invention in the form of lines, dots, images, or planes, the required brightness or desired images can be obtained.

(11th invention)
According to an eleventh aspect of the present invention, there is provided a method for manufacturing a light-emitting device, in which a ceramic substrate on which a plurality of silver-based conductive films that supply power to each electrode of a flip-chip light-emitting diode having at least a pair of electrodes is formed is efficiently manufactured. It is something that can be done. In the manufacturing method, first, after a silver-based conductive film is formed at a predetermined position on a ceramic substrate, a nickel thin film is formed on the upper surface of the silver-based conductive film at least at a portion where the flip-chip type light emitting diode is disposed. A layer and a gold thin film layer are formed. The conductive film on the ceramic substrate has at least a pair of electrodes, and these are patterned into a matrix shape, a column shape, or a row shape.

  A reflector formed with a phosphor film that converts light of at least a plurality of flip-chip light emitting diodes that emit near-ultraviolet light into blue, red, green, and white light includes an inorganic adhesive, such as a ceramic adhesive or It is placed on the ceramic substrate and / or the silver-based conductive film via a glass-based adhesive, and is baked and bonded by heating. Next, the wiring and the electrode of the flip-chip type light emitting diode are bonded together by placing eutectic solder between them and heating. Since the firing temperature of the inorganic adhesive, for example, the ceramic adhesive or the glass adhesive, is higher than the melting point of the eutectic solder, it is reliable to attach the electrode of the flip chip type light emitting diode to be attached later and the wiring. Improves sex.

(Twelfth invention)
According to a twelfth aspect of the present invention, there is provided a method for manufacturing a light emitting device, wherein the silver-based conductive film, the nickel thin film layer, and the gold thin film layer are formed by vapor deposition, electrolysis or electroless plating. The silver conductive film, nickel thin film layer, and gold thin film layer formed by the vapor deposition or the plating are less affected by the temperature of an inorganic adhesive, eutectic solder, or the like, and are peeled by aging. There is nothing to do.

(13th invention)
In the method for manufacturing a light emitting device according to the thirteenth aspect, a large number of packages each including at least a reflector and a wiring are formed on a single ceramic substrate. After the electrodes of the flip-chip type light emitting diodes are connected by gold-tin eutectic solder on the wirings in the respective packages, the reflectors are filled with a translucent silicone resin, and then the ceramic substrate is , Divided one by one.

(14th invention)
According to a fourteenth aspect of the present invention, there is provided a method of manufacturing a light emitting device, wherein the ceramic substrate is half-cut with a laser for each package, and the electrode of the flip chip type light emitting diode is gold-tin eutectic solder on the wiring in each package. Connected. Then, after filling each reflector with translucent silicone resin, the ceramic substrate is divided into each package, and each one becomes the final product. The final product may be provided with a fluorescent film and / or a lens as required.

(15th invention)
According to a fifteenth aspect of the present invention, there is provided a method for manufacturing a light emitting device, wherein a half cut line is inserted for each package at the time of press molding at a green sheet stage where the ceramic substrate is unfired. Thereafter, the green sheet is fired to become a ceramic substrate. The ceramic substrate is connected to wiring such as the silver-based conductive film and a reflector. In the package fabricated on the ceramic substrate, the electrodes of the flip chip type light emitting diode are connected by gold-tin eutectic solder. Then, after filling each reflector with translucent silicone resin, the ceramic substrate is divided into each package, and each one becomes the final product. In addition, after firing the green sheet, the ceramic substrate can be half-cut with a laser or a cutter.

  FIG. 1 is a schematic diagram for explaining a state in which a flip chip type light emitting diode is mounted on a conductive film formed on a ceramic substrate, in which (a) is a plan view and (b) is a first embodiment of the present invention. Is a sectional view, (C) is a back view, and (D) is a side view. 1 (a) to 1 (d), a light emitting device 10 includes flip chip type light emitting diodes 11, 11 'and electrodes connected to electrodes (not shown) of the flip chip type light emitting diodes 11, 11'. A ceramic substrate 12 having a conductive film 121 formed in a shape that improves heat dissipation of current flowing between the electrodes, and reflects light attached to the conductive film 121. And at least a reflector 13. As the flip-chip type light emitting diodes 11 and 11 ′, for example, those emitting near ultraviolet light of 320 μm to 650 μm, preferably 405 μm were used.

  In the conductive film 121, for example, two sets of electrodes 122 to 125 in which the electrodes of two flip-chip light emitting diodes 11 and 11 'are connected in series are provided in series. Further, through holes 126 each having a ¼ circular shape are provided at four corners of the ceramic substrate 12 and the conductive film 121, and a conductive member connected to the conductive film 121 is formed on the entire inner surface thereof. . The conductive film 121 is, for example, a silver-based conductive film, and a nickel thin film layer (not shown) and a gold thin film layer (not shown) are formed on the flip chip type light emitting diodes 11 and 11 ′ from the electrode 122 to the electrode 125. The counter electrode is not formed by vapor deposition or plating. The silver-based conductive film is silver or an alloy of silver and platinum and / or palladium.

  The conductive film 121 provided on the ceramic substrate 12 is connected to the conductive films 141 and 142 formed on the back surface of the ceramic substrate 12 through a ¼ circular through hole 126. The light emitting device 10 is connected to the wiring of the printed wiring board 14 through the conductive films 141 and 142 by, for example, solder or the like (not shown, for example, 200 ° C.). The conductive film 121 formed on the ceramic substrate 12 adheres the reflector 13 by firing at 800 ° C. through an inorganic adhesive or the like. As the inorganic adhesive, a ceramic adhesive or a glass adhesive can be used. Specific inorganic adhesives are “bond X” manufactured by Nissan Chemical Industries, “Sumiceram S” manufactured by Asahi Chemical Industries, “Aron Ceramic” manufactured by Toa Kasei Chemical Industry Co., Ltd., “solder glass” manufactured by ThreeBond, Showa Denko "Glass resin" manufactured by the company can be mentioned.

  In addition to the conductive films 141 and 142, a conductive film 127 is formed on the back surface of the ceramic substrate 12. The conductive film 127 is formed on the printed wiring board 14 and connected to the wiring or the like by solder or the like. A ceramic adhesive and eutectic solder are interposed between the conductive film 121, the reflector 13, and the flip-chip type light emitting diodes 11 and 11 ′, and are bonded by heating at 300 ° C., for example. Further, since the melting temperature of the ceramic adhesive is higher than that of the eutectic solder, even if it is connected by a different process, a highly reliable adhesive strength is maintained. The eutectic solder is preferably gold-tin eutectic solder, for example.

  The reflector 13 has, for example, a rectangular opening 132 therein and is provided with a reflection part 131 around the opening 132 so that the flip-chip light emitting diodes 11 and 11 ′ can emit light in a predetermined direction. The reflection part 131 of the reflector 13 can be irregularly reflected by providing fine irregularities on the surface of alumina in addition to a member that reflects light. On the ceramic substrate 12, a conductive film 121 is formed on almost the entire surface together with the electrodes of the flip chip type light emitting diodes 11 and 11 '. Further, flip-chip light emitting diodes 11 and 11 ′ that emit near-ultraviolet light are electrically connected from the electrode 122 to the electrode 125 of the conductive film 121. In addition, a light shielding film may be formed on the back surface of the ceramic substrate 12 so that light from the flip chip type light emitting diodes 11 and 11 ′ is irradiated only forward.

  The flip chip type light emitting diodes 11 and 11 ′ are filled with a translucent silicone resin 133 at the lower part of the reflection part 131 in order to prevent separation from the conductive film 121 due to vibration or the like. Further, for example, a three-color phosphor film 134 that absorbs near-ultraviolet light and converts it into white light is formed on a thin glass plate on the upper part of the reflection part 131, and the flip-chip type light emission is performed. Light emitted from the diodes 11 and 11 'is efficiently converted into white light. For example, the phosphor film 134 is a laminated film having a total thickness of 210 μm formed by repeating coating and heat curing three times in the order of blue, red, and green in a one-component thermosetting silicone resin. Become. Since the phosphor film 134 is thermally cured after applying each color, color unevenness due to a difference in specific gravity or particle diameter of the three pigments compared to a mixture of the three pigments with a binder. There is no.

  For example, silver, an alloy of silver and platinum, an alloy of silver and palladium, or an alloy of silver, platinum, and palladium is formed on the ceramic substrate 12 by the vapor deposition method or the plating method. Similarly to the above, for example, after eutectic solder is formed on the conductive film 121 by vapor deposition or plating, the flip chip light emitting diodes 11 and 11 'are attached by a robot (not shown). . The thickness of the eutectic solder is preferably about 0.2 μm to 0.5 μm, for example.

  After the reflector 13 is placed on the conductive film 121 via a ceramic adhesive, it is fired by passing through a heating furnace (not shown). Since the eutectic solder has a melting point lower than that of the ceramic adhesive, even if the eutectic solder is separately passed through a reflow furnace, the adhesion between the flip chip type light emitting diodes 11 and 11 ′ and the conductive film 121 is not peeled off. The size of the light emitting device 10 is, for example, a rectangle having a length of 6 mm, a width of 1.8 mm, and a thickness of 1.2 mm. The light emitting device 10 is provided with a positioning hole 135 in order to facilitate attachment to the printed wiring board 14 in the correct orientation.

  FIGS. 2 (a) and 2 (b) are a plan view and a cross-sectional view in which a flip chip type light emitting diode and a conductive film are enlarged in the first embodiment of the present invention. On the ceramic substrate 12, a conductive film 121 is formed on the entire surface by vapor deposition or plating. In the vicinity of the electrodes 111 and 112 of the flip chip type light emitting diode 11, the conductive film 121 serves as counter electrodes 122 and 123 having thin tips. Similarly, a nickel thin film layer 22 and a gold thin film layer 23 are formed on the portions to be the counter electrodes 122 and 123 by vapor deposition or plating. For example, a gold-tin eutectic solder is placed between the electrodes 111 and 112 of the flip-chip type light emitting diode 11 and the gold thin film layer 23 and fired by applying heat. Both can be connected without affecting the adhesion.

  FIG. 3A is a plan view for explaining an example in which the light emitting device is used for a backlight of a liquid crystal display panel according to a second embodiment of the present invention, and FIG. 3B is a sectional view thereof. In FIG. 3, the liquid crystal display panel 31 is irradiated with a plurality of light emitting devices 10, 10 ′ having a plurality of flip chip type light emitting diodes 11, 11 ′ from the left-right direction. The arrangement of the one light emitting device 10, 10 ′ can be arbitrarily determined according to the purpose of use of the liquid crystal display panel 31. The light emitting devices 10 and 10 'may be a series of a pair of flip chip type light emitting diodes 11 and 11', only one, and an increased number thereof. The light emitting devices 10 and 10 'can be arranged in a plurality of rows instead of one row.

  The light emitting devices 10 and 10 ′ are attached to the end portion of the light guide plate 32 from both ends. The light guide plate 32 is provided with a light reflection film 33 and the like on the side opposite to the liquid crystal display panel 31. The light emitted from the light emitting devices 10 and 10 ′ brightens the rear part of the liquid crystal display panel 31 by the light reflecting film 33 while passing through the light guide plate 32. Since the light emitting devices 10 and 10 ′ are reduced in size, the light emitting devices 10 and 10 ′ are sized to be attached to the end portion of the light guide plate 32 as a backlight of the small liquid crystal display panel 31. According to the present invention, the brightness can be improved by eliminating the submount and the light emitting diode assembly substrate and providing the plurality of flip chip type light emitting diodes 11 and 11 ′. It was possible to make it suitable for a backlight.

  The eutectic solder for connecting the electrodes of the flip chip type light emitting diodes 11 and 11 'and the electrode 122 of the conductive film 121 to the electrode 125 is eutectic solder paste, eutectic solder and flux, or gold-tin eutectic solder paste. Can be connected using. The eutectic solder can be pre-applied with a flux or the like when the two are connected. The gold-tin eutectic solder paste used in this example was 80% by weight of gold, 20% by weight of tin, and flux (manufactured by Arakawa Chemical), and the adhesion area was 0.23 × 0.23 μm. The adhesive strength was about 800 to 900 g.

  FIG. 4 is a diagram for explaining a case where a large number of light emitting devices are taken from a ceramic substrate in the third embodiment of the present invention. 4, a large number of light emitting devices 41, 42, 43, 44,... Are provided on one ceramic substrate. The light emitting devices 41, 42, 43, 44,... Are provided with through holes 45 at the four corners thereof, and are formed on each ceramic substrate by cutting lines 46 to 51 passing through the centers of the through holes 45. To be separated. The through hole 45 has only a quarter circular portion on one ceramic substrate. In other words, one through hole 45 is shared by the four ceramic substrates, so that the conductive member formed inside and the labor for separation can be saved.

  The ceramic substrate can be divided after a half-cut line is put in advance by a laser and a conductive film, a reflector, a flip chip type light emitting diode and the like are attached to complete a final product. Another method is to insert a half-cut line at the stage of the green sheet before firing the ceramic substrate, fire it into a ceramic substrate, and then conduct the conductive film, reflector, flip chip type light emission in the same manner as described above. After the diode or the like is attached and the final product is completed, it can be divided.

  FIGS. 5A to 5C are diagrams for explaining the pattern of the conductive film formed on the ceramic substrate in the fourth embodiment of the present invention. In FIG. 5A, one ceramic substrate is provided with light emitting devices 51, 52, 53, 54,. The through holes 55 provided in the ceramic substrate are provided so as to be shared by half each other in the longitudinal direction of each ceramic substrate. In the light emitting devices 51, 52, 53, 54,..., Conductive films are formed in contrast to lines in the x-axis direction and the y-axis direction (cutting line).

  In FIG. 5 (b), one ceramic substrate is provided with light emitting devices 51 ', 52', 53 ', 54',. The through holes 55 provided in the ceramic substrate are provided so as to be shared by half in the longitudinal direction of each ceramic substrate, as in FIG. In the light emitting devices 51 ′, 52 ′, 53 ′, 54 ′,..., Conductive films are alternately formed with respect to the center line in the x-axis direction.

  5C, one ceramic substrate is provided with light emitting devices 51 ″, 52 ″, 53 ″, 54 ″,. The through holes 55 provided in the ceramic substrate are provided so as to be shared in half in the longitudinal direction of each ceramic substrate, as in FIGS. The light emitting devices 51 ″, 52 ″, 53 ″, 54 ″,... Have a conductive film formed so as to be separated from the line in the x-axis direction substantially at the center.

  The shape of the conductive film is not limited to that shown in FIGS. 4 and 5, and the design can be changed to any shape in consideration of heat dissipation, reflector adhesion, and the like. The through holes in FIG. 5 can also be provided in a circular shape at the four corners. Moreover, although the through hole has a circular shape and a substantially elliptical shape, it is not limited to this shape.

  FIG. 6 (a) is a plan view for explaining a light emitting device comprising a single assembly in which six flip chip type light emitting diodes are formed on a ceramic substrate in the fifth embodiment of the present invention. ) Is a front view thereof. In FIG. 6, the light emitting device 60 is formed with conductive films 61 to 64 and 65 to 68 on which electrodes of flip chip type light emitting diodes (not shown) are placed. The conductive films 61 to 64 connect three flip chip type light emitting diodes in series. The conductive films 65 to 68 connect other three flip chip type light emitting diodes in series. The three flip chip type light emitting diodes connected in series can be connected in series or in parallel by wiring of a printed wiring board, for example.

  FIGS. 7A and 7B are views for explaining an example in which a plurality of light emitting devices are connected in the fifth embodiment of the present invention. 7A, a light emitting device assembly 70 includes light emitting devices 71 to 74. Three flip chip type light emitting diodes are connected in series at the upper and lower stages, and two sets of flip chip type light emitting diodes at the middle stage. Are connected in parallel with each other in series. A light-emitting device assembly 70 'shown in FIG. 7 (b) includes light-emitting devices 75, 76, and 77, and three flip-chip light-emitting diodes connected in series are provided in the upper and lower stages. 7A and 7B, four light emitting devices are shown in the case of four squares and the case where three light emitting devices are connected in series. However, the number and connection method may be arbitrarily set. it can.

  FIG. 8 is a view for explaining a light emitting device according to a sixth embodiment of the present invention, in which four flip chip type light emitting diodes are formed on a ceramic substrate, and is formed of one assembly. In FIG. 8, the light emitting device assembly 80 includes four light emitting devices 81 to 84. One light-emitting device 81 includes conductive films 811 and 812, an S-shaped conductive film 813, and a conductive film 815, and flip chip light-emitting diodes 816 to 819 are attached in series therebetween. In the light emitting device assembly 80, the light emitting device 81 and the light emitting device 82 are in series, the light emitting device 83 and the light emitting device 84 are in series, and the two light emitting devices are in parallel. The light emitting device assembly 80 may be a line light source in a single row, or a plurality of light emitting device assemblies 80 may be a surface light source having an arbitrary length and size. The embodiments shown in FIGS. 6 to 8 are examples in which the through holes are inside the conductive film, and are not divided from each other around the through holes.

  The peel strength was measured when the conductive film according to the example of the present invention was a silver, nickel thin film layer, or gold thin film layer. The tensile strength was increased to 260 grams, 370 grams, 400 grams, and 500 grams, but no peeling occurred. Similarly, when the conductive film was a silver, silver-platinum alloy, or gold thin film layer, it increased to 340 grams, 500 grams, 560 grams, 600 grams, and 620 grams, but did not peel off.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example. The present invention can be modified in various ways without departing from the scope of the claims. Known or well-known materials can be used for the flip-chip type light emitting diode, ceramic substrate, conductive film, eutectic solder, ceramic adhesive and the like of the present invention. The flip chip type light emitting diode of the present invention is not only white, but also a display panel composed of figures (characters, symbols, pictures, images) by combining blue, red, and green alone or in combination to change the color tone. It can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view for explaining a state in which a flip chip type light emitting diode is mounted on a conductive film formed on a ceramic substrate in the first embodiment of the present invention, where (A) is a plan view and (B) is a cross-sectional view. (C) is a back view, (d) is a side view. Example 1 (A) and (b) are a plan view and a cross-sectional view in which a flip chip type light emitting diode and a conductive film are enlarged in the first embodiment of the present invention. (A) is a plan view for explaining an example in which the light emitting device is used for a backlight of a liquid crystal display panel according to a second embodiment of the present invention, and (b) is a sectional view thereof. (Example 2) It is a figure for demonstrating the case where many light emitting devices are taken from a ceramic substrate in 3rd Example of this invention. (Example 3) (A) to (c) are diagrams for explaining the pattern of the conductive film formed on the ceramic substrate in the fourth embodiment of the present invention. (Example 4) (A) is a fifth embodiment of the present invention, and is a plan view for explaining a light-emitting device formed by forming six flip-chip type light emitting diodes on a ceramic substrate and comprising a single assembly. It is the front view. (Example 5) (A) and (B) are diagrams for explaining an example in which a plurality of light emitting devices in the fifth embodiment of the present invention are connected. FIG. 10 is a view for explaining a light emitting device in which four flip chip type light emitting diodes are formed on a ceramic substrate in a sixth embodiment of the present invention, and is formed of one aggregate. (Example 6) (A) is a conventional example, and is a schematic diagram for explaining a state in which a flip chip type light emitting diode consisting of three red, green, and blue is attached to a submount. (B) is also red, green, and blue. It is the schematic for demonstrating the state which attached the submount which attached the flip chip type light emitting diode which consists of three to the light emitting diode assembly board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10 '... Light-emitting device 11, 11' ... Flip chip type light emitting diode 111, 112 ... Electrode 12 ... Ceramic substrate 121 ... Conductive film (silver-based conductive film)
122, 123, 124, 125 ... Counter electrode (electrode)
126 ... Through hole 127 ... conductive film 13 ... reflector 131 ... reflecting part 132 ... opening part 133 ... translucent silicone resin 134 ... phosphor film 135 ... positioning Hole 14 ... Printed wiring board 141, 142 ... Wiring (conductive film)
22 ... Nickel thin film layer 23 ... Gold thin film layer 24 ... Eutectic solder (gold-tin eutectic solder)
DESCRIPTION OF SYMBOLS 31 ... Liquid crystal display panel 32 ... Light guide plate 33 ... Light reflection film 60 ... Light-emitting device 70, 70 '... Light-emitting device assembly 80 ... Light-emitting device assembly

Claims (15)

A ceramic substrate on which a wiring made of a conductive film for supplying electric power is connected to each electrode of a flip-chip type light emitting diode having a pair of electrodes;
A reflector attached via adhesive to the ceramic substrate and the upper part of the wiring;
In a light emitting device having a package at least composed of
The wiring formed on the ceramic substrate of the package includes a silver-based conductive film, a nickel thin film layer provided on a top surface of the silver-based conductive film, at least in a portion where the flip-chip light emitting diode is disposed, It is composed of a gold thin film layer provided on a nickel thin film layer,
A light emitting device, wherein a gold thin film layer of the wiring and an electrode of the flip chip type light emitting diode are connected by gold-tin eutectic solder.   The light-emitting device according to claim 1, wherein the silver-based conductive film, the nickel thin film layer, and the gold thin film layer are formed by vapor deposition or plating.   The light-emitting device according to claim 1, wherein the silver-based conductive film is silver or an alloy of silver and platinum and / or palladium.   The light-emitting device according to any one of claims 1 to 3, wherein the adhesive connecting the reflector is an inorganic adhesive.   The light emitting device according to claim 1, wherein the reflector is filled with a translucent silicone resin.   The wiring for connecting a plurality of flip-chip type light emitting diodes arranged inside the reflector is formed so as to substantially cover at least the ceramic substrate inside the reflector. 6. The light-emitting device described in any one of 5 above.   The light emitting device according to claim 1, wherein the wiring provided on the ceramic substrate connects a plurality of flip chip light emitting diodes in series.   2. The flip chip type light emitting diode is characterized in that two sets of three connected in series are arranged in a regular hexagon to form one aggregate and are arranged inside the reflector. The light-emitting device according to claim 1.   2. The flip-chip type light emitting diode according to claim 1, wherein two sets of the flip chip type light emitting diodes connected in series are arranged in a square to form one aggregate and are arranged inside the reflector. The light-emitting device according to claim 6.   Four of the flip-chip type light emitting diodes are connected in series, arranged in a square by making one pattern of wiring into an S shape, and are arranged as one assembly, and are arranged inside the reflector. The light-emitting device according to claim 1, wherein the light-emitting device is a light-emitting device. A wiring made of a conductive film for supplying power to each electrode of a flip-chip light emitting diode having a pair of electrodes is formed with a silver-based conductive film on a ceramic substrate, and at least on the upper surface of the silver-based conductive film A nickel thin film layer is formed on a portion where the flip chip type light emitting diode is disposed,
Furthermore, a gold thin film layer is formed on the nickel thin film layer,
After applying an inorganic adhesive between the ceramic substrate and the upper portion of the wiring, and a reflector, and heating and bonding to manufacture a light emitting device package attached with a reflector,
A method of manufacturing a light-emitting device, characterized in that a gold thin film layer of the wiring and an electrode of the flip-chip light-emitting diode are connected by gold-tin eutectic solder.   12. The method for manufacturing a light emitting device according to claim 11, wherein the silver-based conductive film, the nickel thin film layer, and the gold thin film layer are formed by vapor deposition or plating.   Each package is formed in large numbers on a ceramic substrate, and the electrodes of the flip-chip type light emitting diodes are connected to the wirings in the respective packages by gold-tin eutectic solder, and then the transparent silicone is placed in each reflector. 13. The method for manufacturing a light emitting device according to claim 11, wherein the method is obtained by dividing the ceramic substrate after filling with a resin.   Each package is formed in large numbers on a ceramic substrate, the ceramic substrate is half-cut by a laser, and the electrodes of the flip chip type light emitting diode are connected to the wiring in each package by gold-tin eutectic solder. The method for manufacturing a light emitting device according to claim 11 or 12, wherein each of the reflectors is obtained by dividing the ceramic substrate after filling each reflector with a translucent silicone resin.   Each package is a green sheet of a ceramic substrate, and a half-cut wire is inserted at the time of press molding, and the electrode of the flip chip type light emitting diode is connected to the wiring in each package by gold-tin eutectic solder. 13. The method of manufacturing a light emitting device according to claim 11, wherein the ceramic substrate is obtained after the reflector is filled with a translucent silicone resin. 13.

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