JP2004363632A - Light-emitting device and forming method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device which has stable light emission characteristics, high in light usability, and high in yield, regardless of usage environment, and which can be formed small. <P>SOLUTION: The light-emitting device includes a transparent support with a recess and an LED chip, wherein the concave is provided with a transparent adhesive containing a fluorescent material, and the LED chip is provided on the transparent adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting device used for a light source used for various control devices such as an LED display, an optical communication device, an optical printer head and an optical sensor, and more particularly, has high mass productivity and is reliable regardless of the use environment. And a light-emitting device with high reliability.

  Today, with the development of silicon technology such as LSI, optical communication technology and the like, it has become possible to process and transmit a large amount of information at high speed. Along with this, social demands for a full-color and high-definition optical printer head capable of processing a large amount of image information, an optical sensor used for a display device and various control devices, and the like are increasing. In particular, light-emitting devices with stable characteristics and miniaturization are extremely demanding and variously developed. Documents that disclose such a light emitting device include Patent Document 1 and Patent Document 2.

FIG. 5 shows a specific example of the light emitting device. One electrode of the LED chip 502 is connected to a lead frame using an Ag paste 504 or the like, and the other electrode of the LED chip 502 is separately electrically connected to the conductive wire 503 using an Au wire or the like. The light emitting device is molded into a lens shape 501 with an epoxy resin or the like on the LED chip in order to collect and efficiently extract light from the LED chip. A light-emitting device that is electrically connected using a conductive wire and covered with a mold member can be formed relatively easily with good yield and small size.
JP-A-7-231120 JP-A-7-22651

  However, if there is a conductive wire or the like on the light emitting surface side, the light emitted by the LED chip will be behind the conductive wire, the bonding portion of the conductive wire, and the electrode. There is a problem that light or the like emitted from the lower part of the electrode on the light emitting surface side provided on the LED chip does not effectively go outside. Further, when irradiating the recording medium such as photosensitive paper with the LED chip, there is an extra thickness of at least the conductive wire between the LED chip and the recording medium. Therefore, the conductive wires cannot be close to each other because of obstruction. Further, even when light emitted from the LED chip is used as a spotlight using a light-blocking member such as an aperture, the conductive wire or the like may be shaded. For this reason, uniform optical characteristics could not be obtained, and some products were defective. In the case where a plurality of electrodes such as a positive electrode and a negative electrode are formed on one surface side of the light emitting element, problems such as light shielding tend to be more remarkable because the number of conductive wires increases.

  Further, when condensing light from the LED chip, a resin or the like is molded on the LED chip to integrally form a lens portion or the like. In order to further increase the light condensing power by the lens portion, the thickness of the mold portion, which is the apex of the lens portion from the LED chip surface, may be increased. When an LED chip electrically connected by a conductive wire is integrally molded with a mold member, the characteristics of the light emitting device tend to deteriorate in a use environment in which a temperature difference is extremely large as the thickness of the mold member increases. In particular, it becomes remarkable in a light emitting device having a large number of connection portions of conductive wires.

  Further, in order to prevent the inclusion of bubbles and the like, stabilize the light emission characteristics, and increase the light condensing power, it is preferable to use a lens formed by transfer molding or the like. However, the resin is molded into a desired shape at a relatively high pressure during resin molding. Due to various forming conditions such as resin shrinkage generated during cooling and curing, it is difficult to integrally mold an LED chip electrically connected with a conductive wire. There is a problem that the lens portion and the light emitting element cannot be formed in close contact with each other to be compact.

  Therefore, the light emitting device having the above configuration is not sufficient at present when better light emitting characteristics are required, and further improvement in characteristics is required. In view of such a problem, the present invention provides a light emitting device having an LED chip that is electrically connected to an external electrode by a conductive wire. A light emitting device.

The present invention is directed to disposing an LED chip on a light-transmitting support via a light-transmitting adhesive, and having an electrode on a surface side of the LED chip opposite to a surface in contact with the light-transmitting adhesive; This is a light-emitting device in which an external electrode provided on a light-transmitting support is electrically connected to an external electrode by a conductive wire. Further, the LED chip is a light emitting device having a positive electrode and a negative electrode respectively on a semiconductor formed on a light-transmitting insulating substrate, and includes a protective member for protecting a conductive wire, and a reflective member on the protective member. And a light emitting device having the same. Further, the light-emitting device includes a light-transmitting adhesive containing a fluorescent substance. This is also a light-emitting device in which a light-blocking member having at least one opening is provided on a light-transmitting support. Furthermore, the light-emitting device has a light-transmitting support having a lens unit that collects at least a part of light from the LED chip.
The light-emitting device according to claim 1 of the present invention is a light-emitting device having an LED chip bonded with a light-transmitting adhesive on a support having a recess, wherein the support is a light-transmitting support. The light-transmitting adhesive contains a fluorescent substance.
The light-emitting device according to claim 2 is the light-emitting device according to claim 1, wherein the translucent support has a first recess for accommodating the LED chip, and a bottom portion of the first recess. And the recess is provided.
Further, in the light emitting device according to the third aspect, in the light emitting device according to the first or second aspect, the external electrode provided on the translucent support is opposed to a surface in contact with the translucent adhesive. An electrode of the LED chip is provided on a surface side, and the external electrode and the electrode are connected by a conductive wire.
The light emitting device according to a fourth aspect is the light emitting device according to the third aspect, further comprising a protection member that protects the LED chip and the conductive wire.
According to a fifth aspect of the present invention, in the light emitting device according to any one of the first to fourth aspects, the translucent support having a plurality of the concave portions and the translucent member having the plurality of the concave portions are provided. It has a plurality of the LED chips respectively bonded by an adhesive, and the translucent adhesive disposed in at least one of the plurality of recesses contains a fluorescent substance. .
Furthermore, the light emitting device according to claim 6 is characterized in that, in the light emitting device according to claim 5, at least one light shielding portion is formed between adjacent LED chips in the translucent support. I do.

  Furthermore, the step of fixing the LED chip to the concave portion of the light-transmitting support via a light-transmitting adhesive, and the steps of: connecting the electrode of the LED chip and the external electrode provided on the light-transmitting support to a conductive wire And a step of forming a reflective member on the conductive wire and the LED chip disposed in the concave portion of the translucent support.

  As described above, by forming the light extraction portion side and the electrical connection portion side separately from each other with respect to the function of the LED chip, the electrical connection portion can be relatively easily formed with high reliability by the conductive wire. Can be. It is possible to provide a light-emitting device in which disconnection of an electrical connecting member due to pressure due to formation of a light extraction portion or internal stress of a sealing member is prevented. In particular, by fixing via a translucent adhesive, light can be efficiently guided and the optical axis can be aligned. Further, a light extraction member can be separately formed. This makes it possible to make the light extraction unit a light emitting device that is extremely free of air bubbles and has excellent light collecting power.

  As a result of various experiments, the inventor of the present application has found that a light emitting device having good mass productivity and stable light emitting characteristics regardless of the use environment can be obtained by separating the function of the light extraction portion and the conductive wire formation portion. Have been found, and based on this, the present invention has been accomplished.

  It is not clear why the light emission characteristics are stable regardless of the usage environment by separating the light extraction part and the conductive wire formation part, but it is integrally molded with the LED chip electrically connected by the conductive wire. It is thought to be related to the light extraction site.

That is, when the mold member is formed into a lens shape and integrally molded in order to efficiently condense the light from the LED chip, the life may be shortened under a high-temperature and humidity cycle with an increase in the light-condensing rate. In particular, the internal stress increases as the thickness of the member forming the lens from the LED chip surface increases. Therefore, it is considered that the conductive wire constituting the LED chip is disconnected due to the internal stress of the mold member forming the lens portion under a use environment having a large temperature difference. When a lens having a higher light-collecting ability is formed, it is preferable to use transfer molding or the like that requires a molding pressure of about 150 to 200 kg / cm ² , depending on the type of resin. In this case, the conductive wire electrically connected to the electrode of the LED chip or the like may be broken due to pressure during molding of the light-transmitting support.

  According to the present invention, a light-transmitting support for extracting light from an LED chip and a portion connected by a conductive wire are formed separately. Specifically, FIG. 1B shows an example of a chip type LED. In FIG. 1B, in order to form a lens having a high light-collecting ability, a light-transmitting support body 101 having a lens portion integrally formed by transfer molding is used. A silver-plated copper plate serving as the external electrode 105 is embedded in the translucent support 101. In addition, a concave portion on which the LED chip is disposed is formed on the translucent support opposite to the lens unit. Inside the concave portion, a concave portion whose bottom is convex toward the outside is further provided. An LED chip is die-bonded in the concave portion using an epoxy resin as the translucent adhesive 104 so that the optical axis is aligned with the lens portion of the translucent support 101. After the die-bonding resin is cured, the external electrodes 105 exposed in the recesses from the light-transmitting support 101 and the electrodes of the LED chip 102 having a gallium nitride-based compound semiconductor on a sapphire substrate are connected to a conductive wire 103 by gold. Wire bonding was performed using a wire. After that, the LED chip 102, the conductive wire 103, the external electrode 105, and the like in the concave portion were provided with a protective member / reflective member 106 in which silicon rubber containing barium titanate was applied and cured to form a light emitting device.

  With such a structure of the light emitting device, a light extraction portion and a conductive wire formation portion are separated from each other, so that a light emitting device having stable light emission characteristics even in a high temperature cycle can be obtained. In particular, in the present invention, it can be a light extraction portion with improved light-collecting ability. By connecting the translucent support and the LED chip via a translucent adhesive, light from the LED chip can be efficiently guided and the optical axis of the light emitting device can be easily adjusted. Hereinafter, each configuration of the present invention will be described in detail.

(Translucent supports 101, 201, 301, 401)
As the translucent support 101 used in the present invention, an LED chip 102 which is a semiconductor light emitting element can be mounted, and at least a part of the emission wavelength from the LED chip 102 or the emission wavelength using light from the LED chip 102. Has a substantially light-transmitting property.

  Various shapes and materials can be used for such a light-transmitting support 101 as required or desired. Specifically, various kinds of convex lenses and concave lenses can be formed on the translucent support 101. In addition, a recess such as a concave shape or a semicircular shape can be formed in the light-transmitting support, and can be used for mounting the LED chips 102. A lens effect can be provided by using such a depression. Therefore, at least a part of the bottom in the concave portion can be formed into various shapes such as a convex shape and a concave shape, and desired light distribution characteristics can be obtained. In addition, by forming the concave portion into a desired size or shape, the amount of the light-transmitting adhesive 104 that fixes the LED chips 102 mounted on the light-transmitting support 101 can be variously controlled. One or more LED chips 302 may be provided on the translucent support. In this case, it is desirable that the light-shielding members 310 be arranged between the LED chips 302 or colored in order to be driven independently.

  Since the translucent support 101 of the present invention can be freely designed, in particular, separately from the conductive wire, which is an electrical connection portion of the LED chip, it is formed by using compression molding, transfer molding, or the like in which molding pressure is applied. be able to. That is, a lens portion having excellent optical characteristics can be formed on the translucent support 101 itself.

  When the translucent support 101 is affected by heat from an LED chip or the like, a material having a small coefficient of thermal expansion is preferable in consideration of the adhesion to the translucent adhesive 104. The inner surface of the translucent support 101 may be embossed to increase the bonding area, or may be plasma-treated to improve the adhesion with the translucent adhesive 104.

  As such a translucent support 101, a resin such as a polycarbonate resin, a polyphenylene sulfide (PPS), a liquid crystal polymer (LCP), an ABS resin, an epoxy resin, a phenol resin, an acrylic resin, an imide resin, and a PBT resin can be used. .

  Various methods can be used for forming the translucent support 101 of the present invention, but it can be suitably formed by transfer molding or compression molding.

  Transfer molding is a type of molding method for thermosetting plastic materials. The material is preheated and softened in a pot, which is pressed by a plunger through an orifice into a sealed and heated mold at a relatively high molding pressure. The plastic material is thermoset in a mold to form. Therefore, uniform curing and accurate dimensions are possible, and it can be suitably used when a part of the translucent support of the present invention is formed into a lens.

  On the other hand, in the compression molding, a molding material is charged into a mold, the mold is pressurized by a hot press, plastic flow is caused by heat and pressure, and the molding material is uniformly filled in the cavity, so that a transparent support having a desired shape is formed. Can be formed.

  In the present invention, translucency means that at least a part of the emission wavelength from the LED chip or the emission wavelength using light from the LED chip can be substantially transmitted. In addition, having translucency with respect to at least a part of the emission wavelength from the LED chip means that substantially all of the light emitted from the LED chip transmits through the translucent support, This includes the case where a filter effect is provided for light emitted from the LED chip, such as when the support contains a coloring member. Having translucency with respect to the emission wavelength using light from the LED chip means that a phosphor is contained in a translucent support or a translucent adhesive and the wavelength is converted by the phosphor emitted from the LED chip. This also includes the case where the transmitted light passes through the translucent support.

(Light-emitting elements 102, 202, 302, 402)
The LED chip 102 which is a light emitting element used in the present invention includes GaAlN, ZnS, ZnSe on a substrate by liquid phase epitaxy, MBE (molecular beam vapor phase epitaxy), MOVPE (metal organic chemical vapor phase epitaxy) or the like. An LED chip in which a semiconductor such as SiC, GaP, GaAlAs, AlInGaP, InGaN, GaN, AlN, InN, and AlInGaN is formed as a light emitting layer is preferably used. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, and a PN junction, a heterostructure, and a double heterostructure. The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor light emitting layer and the degree of mixed crystal thereof. Further, the light emitting layer may have a single quantum well structure or a multiple quantum well structure to have a quantum effect.

  In general, an LED chip has a positive electrode and a negative electrode formed on a surface facing each other via a semiconductor in order to supply current to a light emitting layer provided on a semiconductor substrate. When such an LED chip is used in the present invention, only one of them can be electrically connected by a conductive wire. On the other hand, it is necessary to install the light-transmitting electrode 205 on the light-transmitting support 201 via a light-transmitting adhesive 204. When a semiconductor layer is formed on an insulating substrate such as alumina or sapphire to improve the quality of a crystal such as a gallium nitride-based compound semiconductor, a positive electrode and a negative electrode are formed on the same surface side, and electrical The conduction is established. Therefore, since at least two or more conductive wires are required, the effect of the present invention is particularly remarkable.

  The electrode formed on the semiconductor can be formed as desired by a vacuum evaporation method, various CVD methods utilizing heat, light, discharge energy, or the like, or a sputtering method. The semiconductor wafer on which the electrodes are formed is directly full-cut by a dicing saw in which a blade having a diamond blade is rotated, or a groove having a width larger than the blade width is cut (half cut), and the semiconductor wafer is cut by an external force. Divide. Alternatively, an extremely thin scribe line (meridian) is drawn on a semiconductor wafer, for example, in a grid pattern by a scriber in which a diamond needle at the tip reciprocates linearly, and then the wafer is cut by an external force to cut the semiconductor wafer into chips. A chip 102 can be formed.

(Conductive wires 103, 203, 303, 403)
The conductive wires 103 are required to have good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the electrodes of the LED chip 102 and the external electrodes 105. The thermal conductivity is preferably at least 0.01 cal / cm ² / cm / ° C., more preferably at least 0.5 cal / cm ² / cm / ° C. The diameter of the conductive wire 103 is preferably Φ10 μm or more and Φ45 μm or less in consideration of workability and the like. Specific examples of such a conductive wire 103 preferably include those using metals such as gold, copper, platinum, and aluminum and alloys thereof. Such a conductive wire 103 can easily connect the electrode of each LED chip 102 and the external electrode 105 with a wire bonding device.

(Translucent adhesive 104, 204, 304, 404)
The translucent adhesive 104 used in the present invention fixes the translucent support 101 and the LED chip 102 which is a light emitting element, and at least a part of the emission wavelength from the LED chip 102 or the light from the LED chip 102. It has substantially translucency with respect to an emission wavelength using light. Therefore, it is required that the transparent substrate 101 or the external electrode 205 has good adhesion and high transmittance of desired light.

In an LED chip in which electrodes are arranged to face each other via a semiconductor, it is necessary to emit light through the electrodes. Therefore, at least a part of the external electrode 205 provided on the light-transmitting support 201 is formed of a light-transmitting metal oxide such as SnO ₂ , In ₂ O ₃ , ZnO, or ITO, or a metal thin film. The electrodes of the LED chip 202 mounted on the external electrodes 205 can be fixed and electrically connected together with a light-transmitting adhesive 204 containing a light-transmitting electrically conductive member.

Further, it is preferable that the translucent adhesive has good thermal conductivity in order to conduct heat radiation from the light emitting element to the package electrode. The heat conductivity may be increased and one electrode of the LED chip may be electrically connected via a translucent adhesive. As such a translucent adhesive, a resin binder containing a translucent conductive member is preferable. Specific conductive members satisfying the above requirements include SnO ₂ , In ₂ O ₃ , ZnO and ITO. In addition, various binders such as an epoxy resin may be used as the binder. The light-transmitting adhesive 104 may contain a fluorescent substance and / or a coloring substance. By including a fluorescent substance, light from the fluorescent substance or light from the fluorescent substance and the LED chip can be emitted as desired. Further, by containing a coloring substance such as a coloring dye or a coloring pigment, it is possible to have a filter effect of adjusting the emission wavelength from the LED chip as desired.

  The concave shape of the translucent support 101 is made to be a convex lens or a concave lens shape, and desired optical characteristics are obtained by injecting a translucent adhesive 104 having a different refractive index from the translucent support 101. You can also. Specific examples of such a translucent adhesive 104 include various materials such as epoxy resin, silicone resin, and water glass.

(External electrodes 105, 205, 305, 405)
The external electrode 105 used in the present invention is to be used to supply power from the outside to the LED chip 102 provided on the translucent support 101. The external electrode 105 can be formed in various sizes and shapes from the viewpoint of electrical conductivity, heat dissipation, characteristics of a light emitting element, and the like. The external electrode 105 may be a metal plate inserted into the translucent support 101 or may be formed on the translucent support 101 by various methods.

The external electrode 105 can be integrally formed by inserting a metal plate when forming the translucent support 101. Further, after the light-transmitting support 301 is formed, a metal can be formed by vapor deposition, plating, or sputtering. Alternatively, a light-transmitting metal oxide such as SnO ₂ , In ₂ O ₃ , ZnO, or ITO can be used as the external electrode 105.

  In the case where a plurality of LED chips 302 are arranged on the translucent support 301, it is preferable that the LED chips 302 have good thermal conductivity in order to radiate heat emitted from the LED chips to the outside. Further, by using a part of the external electrode 105 to form a reflection member, the light use efficiency can be improved. In this case, it is preferable that the external electrode 105 provided on the translucent support 101 has a high reflectance with respect to light emitted from the LED chip. As such an external electrode 105, a copper or bronze plate whose surface is plated with a noble metal such as silver or gold is preferably used.

(Protection members 106 and 406)
The protection member 106 used in the present invention is preferably provided to protect the LED chip 102 as a light emitting element, the conductive wire 103 for electrical connection thereof, and the like from external force, dust, moisture, and the like. Therefore, the protection member 106 and the LED chip 102 and the like may be formed in close contact with each other, or may not be in close contact with the light emitting element and the like for heat dissipation and stress relaxation. When the protection member 106 is in close contact with the LED chip 102, the conductive wire 103, or the like, it is preferable to use an elastic resin so that the conductive wire does not break due to internal stress or the like. Further, when a resin having low elasticity is used, it is desirable to form the resin thinly. As a specific material for the protective member 106, a resin having excellent weather resistance such as an epoxy resin, a urea resin, a silicon resin, a fluorine resin, and a polycarbonate resin is suitably used. Such a protective member 106 can be easily formed by injecting a resin from a nozzle into a concave portion of the translucent support so as to cover the LED chip 102 and the like.

(Reflecting members 107 and 407)
The reflecting member 107 is preferably provided to efficiently direct light emitted from the LED chip 102 toward the light-transmitting support. The reflection member 107 can be formed on the protection member 106, or can have a structure that serves both as the reflection member and the protection member. Further, only the reflection member 107 can be formed. The reflecting member 107 can be formed by including a member having high reflectance, such as titanium oxide or barium titanate, in a resin or glass. Further, a metal may be provided on the protection member to serve as a reflection member.

  The material used for the reflection member 107 may be the same member as the protection member 106. In addition, when used for the reflective member 107, the material used for the protective member 106 may be formed of a member having different stress, heat dissipation, and refractive index.

(Backlight)
A backlight light source that can be used for a liquid crystal device or the like as shown in FIG. 2 can be configured by using the present invention. FIG. 2 shows a structure in which the translucent support 201 of the present invention can be used also as a light guide plate of a backlight light source. The reflection layer 210 was formed except for the main surface of the light guide plate made of polycarbonate and the end surface on which the LED chips 202 were mounted. Such a reflective layer 210 is attached with an epoxy resin plate or the like containing titanium oxide. By providing the reflective layer 210, the light emitted from the LED chip 202 can be efficiently emitted from the main surface of the light guide plate.

  Here, an LED chip 202 having a gallium nitride-based compound semiconductor formed on a SiC substrate was used as a light emitting element. The LED chip 202 has aluminum positive and negative electrodes formed on the SiC substrate surface side and the semiconductor surface side facing the SiC substrate via the semiconductor light emitting layer by a sputtering method, respectively. The electrode provided on the SiC substrate side is formed thin so that light emitted from the light emitting layer can be transmitted.

On the end surface of the light guide plate on which the LED chips 202 are mounted, ITO having translucency as an external electrode 205 and an Al film formed thereon are formed in a desired shape by a sputtering method. The SiC substrate surface side on which the electrodes of the LED chip 202 are formed and the external electrode 205 having a light-transmitting property at least under the LED chip are fixed with a light-transmitting adhesive 204 containing SnO ₂ and electrically. Conduct continuity. As a result, the external electrodes 205 other than the portion where the LED chip 202 is mounted are formed by stacking Al on ITO, functioning as a reflective layer, and improving the conductivity. The other electrode provided on the semiconductor surface side of the LED chip 202 is wire-bonded to another external electrode provided on the light guide plate using a conductive wire 203. A liquid crystal display device can be formed by disposing a liquid crystal device (not shown) on the backlight thus formed.

(Write / read light source)
The light source of an optical printer head, an image scanner, and the like can be configured as shown in FIGS. 3 and 4 using the present invention. FIG. 4 shows a light-emitting device of the present invention which is used for a writing light source such as an optical printer head as shown in FIG. As the translucent support 301, long glass was used. As the LED chip 302, a gallium nitride-based compound semiconductor formed on a sapphire substrate is used. On the LED chip 302, a P-type electrode and an N-type electrode are formed on the same plane side of the semiconductor. A Cu film was formed as a light shielding member 310 on glass by vapor deposition. The light-blocking member 310 is provided with at least one opening, and functions as an aperture. Further, a conductive pattern of Cu is formed as an external electrode 305 on the surface side opposite to the surface on which the light shielding member 310 is provided via the light transmitting support 301.

  The sapphire substrate of the LED chip 302 was bonded to the surface of the translucent support 301 on which the external electrodes 305 were provided, using an epoxy resin as a translucent adhesive 304. In FIG. 3, two LED chips 302 are arranged on a light-transmitting support 301, and an electrode provided on a P-type semiconductor of one LED chip 302 and an external electrode are formed using Au wires 303. Connected by wire bonding. Similarly, an electrode provided on the N-type semiconductor of the other adjacent LED chip is wire-bonded to another external electrode.

  Between the LED chips 302, an electrode provided on the N-type semiconductor of one LED chip and an electrode provided on the P-type semiconductor of the other LED chip are connected in series by direct wire bonding in order to connect them in series. It has been made. When power is supplied to the LED chips connected in series in this manner, point emission is performed from the LED chip 302 via the light-transmitting adhesive 304 and the light-transmitting support 301 provided with the aperture. As a result, the light extraction portion and the wire do not overlap each other, and the wire is not shaded, and the photosensitive paper or the like can be exposed in close contact.

  When the light emitting device of the present invention is used as a full-color optical printer head as shown in FIG. 4, each of the RGB emission wavelengths can be formed by an LED chip 402 using the same gallium nitride compound semiconductor or the like. That is, by changing the composition of the gallium nitride-based compound semiconductor, an LED chip capable of emitting blue light and green light can be formed. An LED chip 402 is fixed to a concave portion of a light-transmitting support body 401 in which a lens is formed and which is optically separated for each of RGB by a light-transmitting adhesive 404 such as an epoxy resin. In the concave portion of the translucent support corresponding to the red light emitting portion, a translucent adhesive 411 containing a fluorescent substance which is excited by light from the LED chip and emits red light in an epoxy resin is used. The LED chip is bonded on the sapphire substrate side. External electrodes 405 for driving each LED chip are formed on the rear surface side of the translucent support 401. Each external electrode 405 and the electrode of the LED chip are wire-bonded with a conductive wire 403 such as a gold wire. Similarly, the blue type and the green type have the same configuration except that the fluorescent material is not contained in the translucent adhesive. A sealing resin as a protection member 406 or a reflection member 407 which is a reflector may be provided on the rear surface side of the LED chip according to a use situation.

  By including the light-transmitting adhesive 411 such as a resin containing a fluorescent substance in the concave portion of the light-transmitting support, the amount and thickness of the adhesive can be controlled, so that the yield is improved. is there. In particular, when a fluorescent substance is contained, the content, the distribution thickness, and the like can be easily controlled by the shape of the concave portion.

Furthermore, specific examples of the fluorescent substance capable of emitting light is red _{aMgO · bLi 2 O · Sb 2} O 3: cMn, eMgO · fTiO 2: gMn, pMgO · qMgF 2 · GeO 2: rMn and the like suitably (However, 2 ≦ a ≦ 6, 2 ≦ b ≦ 4, 0.001 ≦ c ≦ 0.05, 1 ≦ e ≦ 3, 1 ≦ f ≦ 2, 0.001 ≦ g ≦ 0.05, 2.5 ≦ p ≦ 4.0, 0 ≦ q ≦ 1, 0.003 ≦ r ≦ 0.05.) In addition to such a fluorescent substance, other fluorescent substances such as cerium-activated yttrium / aluminum / garnet can also be mixed. The other colors are cerium-activated yttrium aluminum garnet _{(RE 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce phosphor (where, 0 ≦ x <1, 0 .Ltoreq.y.ltoreq.1, RE is at least one element selected from the group consisting of Y, Gd, and La.).

  When used as a sensor light source, each LED chip corresponding to RGB can be arranged close to and capable of emitting white light without optically separating RGB. Light emitted from each LED chip is applied to a medium such as paper on which characters, photographs, figures, and the like are described. The light reflected by the medium is optically configured to enter a light sensor made of single crystal, non-single-crystal silicon, or the like through color filters corresponding to RGB. Light incident on a long light sensor or the like can be read as an electric signal corresponding to each of RGB light.

  Even if the light source for a sensor, which is a reading light source, does not emit light, the temperature of the light source may rise due to preheating that occurs during the standby time. If the semiconductor constituting each LED chip is formed from a different material, temperature characteristics such as light emission output and light emission wavelength will be different. For this reason, even when white light is adjusted at a constant temperature, the color tone may shift due to a temperature change, and accurate information may not be read. Since multicolor light emission can be performed using a semiconductor light emitting element using the same material, there is an advantage that a light emitting device having extremely low temperature dependence can be obtained. Hereinafter, specific embodiments of the present invention will be described in detail, but it goes without saying that the present invention is not limited to only the specific embodiments.

(Example 1)
A chip type LED was formed as a light emitting device. As the chip type LED, an LED chip using an In _0.05 Ga _0.95 N semiconductor having an emission peak of 450 nm was used. For the LED chip, a TMG (trimethyl gallium) gas, a TMI (trimethyl indium) gas, a nitrogen gas and a dopant gas are flowed together with a carrier gas on a cleaned sapphire substrate, and a gallium nitride-based compound semiconductor is formed by MOCVD. Formed.

A desired conductivity type is formed by switching between SiH ₄ and Cp ₂ Mg as the dopant gas. An active layer of InGaN is formed between the contact layer and the cladding layer, which is a gallium nitride semiconductor having N-type conductivity, and the cladding layer, which is a gallium nitride semiconductor having P-type conductivity, to form a PN junction. Was. (A gallium nitride semiconductor is formed at a low temperature on a sapphire substrate to serve as a buffer layer. The P-type semiconductor is annealed at 400 ° C. or higher after film formation.)

  After exposing the surface of each PN semiconductor by etching, each electrode was formed by sputtering. After a scribe line was drawn on the semiconductor wafer thus completed, the wafer was divided by an external force to form an LED chip as a light emitting element.

  On the other hand, a translucent support having a lens portion was formed by transfer molding using polycarbonate as shown in FIG. 1A. External electrodes are inserted into the formed translucent support. The optical axis was aligned so that the sapphire substrate surface of the LED chip faced the lens portion in the concave portion of the translucent support, and was die-bonded with an epoxy resin and cured at 150 ° C. for 2 hours. Thereafter, the external electrodes of the translucent support and the respective electrodes of the LED chip were wire-bonded using Au wires. In order to protect the LED chips, Au wires, and the like in the concave portions of the translucent support, they were sealed with a silicone resin to form a protective member. A light emitting device was formed by applying and curing a silicon resin containing barium titanate on the protective member and providing a reflective member. The same light-emitting device was used except that the distance d between the vertex of the lens portion and the LED chip surface was 3 mm (directivity angle 60 °), 6 mm (directivity angle 30 °), and 9 mm (directivity angle 15 °). Each was formed.

  100 light-emitting devices thus formed were formed, and the average on-axis luminous intensity was measured. Further, a thermal shock at -40 ° C. for 30 min and 100 ° C. for 30 min was repeated 1,000 cycles within 5 min to conduct a gas phase thermal shock test.

(Comparative Example 1)
As shown in FIG. 5, the resin is integrally molded with the external electrode extended and the LED chip mounted thereon and electrically connected, and otherwise the same as in Example 1 from the vertex of the lens portion and the LED chip surface. 100 light emitting devices each having a distance d of 3 mm (directivity angle 60 °), 6 mm (directivity angle 30 °), and 9 mm (directivity angle 15 °) were formed. The average on-axis luminous intensity was measured in the same manner as in Example 1. The results are shown in Table 1 together with Example 1. In addition, a vapor phase thermal shock test was performed to determine the number of light emitting devices in which the conductive wires were broken, and the results are shown in Table 2 together with Example 1.

  With the configuration of the present invention as described above, the light extraction portion and the electrical connection portion using the conductive wire can be formed separately, so that the light emitting element can be relatively easily formed with high reliability. be able to. In particular, a light-emitting device in which disconnection of an electrical connection member due to pressure or internal stress due to formation of a light-transmitting support serving as a light extraction portion can be prevented. In addition, the light extraction unit can be a light emitting device that is extremely low in the inclusion of air bubbles and has excellent light-gathering power.

  With the structure of the present invention, a simpler and more reliable high-luminance light-emitting device can be obtained.

  With the structure of the present invention, a light-emitting element with reduced influence from an external environment, improved reliability, and higher light extraction efficiency can be obtained.

  With the configuration of the present invention, the wavelength of light emitted from the LED chip can be converted. Since the fluorescent substance is contained in the concave portion and adhered thereto, a desired fluorescent substance content can be obtained, and a light emitting device with less variation in emission wavelength can be obtained. In particular, since a certain amount of fluorescent substance can be uniformly contained on the light emitting surface side, a light emitting device with less color unevenness on the light emitting surface can be obtained.

  With the configuration of the present invention, a smaller point light source can be obtained. Accordingly, the present invention can be suitably used for an optical printer head or the like in which the influence of an adjacent light emitting device is extremely reduced. Therefore, the light emitting device can be reduced in size, and the light emitting portion can be made high in light extraction efficiency without the conductive wire being shaded by the conductive wire.

  With the configuration of the present invention, a light-emitting device with higher light-collecting power can be obtained. In particular, by forming the lens portion on the light-transmitting support corresponding to the light extraction side, the light-collecting power can be improved irrespective of the adhesion of the conductive wire.

  By adopting the process of the present invention, a small-sized light-emitting device with high reliability and high light extraction efficiency can be easily formed.

1 is a schematic sectional view of a chip type LED according to the present invention. It is a schematic sectional drawing of other chip type LED which concerns on this invention. FIG. 2 is a schematic sectional view in which the light emitting device of the present invention is configured as a backlight light source. FIG. 3 is a schematic sectional view of an optical printer head using the light emitting device of the present invention. FIG. 9 is a schematic sectional view of a full-color optical printer head using another light emitting device of the present invention. FIG. 2 shows a schematic cross-sectional view of a light emitting device shown for comparison with the present invention.

Explanation of reference numerals

101, 201, 301, 401 ... translucent supports 102, 202, 302, 402 ... LED chips 103, 203, 303, 403 ... conductive wires 104, 204, 304, 404 ... Translucent adhesives 105, 205, 305, 405 ... external electrodes 106, 406 ... protective members 107, 407 ... reflective members 210 ... reflective layers 310, 410 ... light shielding members 411 ... -Translucent adhesive 501 containing a fluorescent substance-Lens part 502-LED chip 503-Conductive wire 504-Conductive adhesive 505-External electrode

Claims (6)

In a light emitting device having an LED chip bonded by a translucent adhesive on a support having a concave portion,
The light-emitting device, wherein the support is a light-transmitting support, and the light-transmitting adhesive contains a fluorescent substance.   The light emitting device according to claim 1, wherein the translucent support has a first recess for accommodating the LED chip, and has the recess at the bottom of the first recess.   An external electrode provided on the light-transmitting support, and an electrode of the LED chip on a surface side opposite to a surface in contact with the light-transmitting adhesive, wherein the external electrode and the electrode are formed of a conductive wire. The light emitting device according to claim 1, wherein the light emitting device is connected.   The light emitting device according to claim 3, further comprising a protection member that protects the LED chip and the conductive wire.   A light-transmitting support having a plurality of recesses; and a plurality of the LED chips bonded to the plurality of recesses by the light-transmitting adhesive, respectively, and the plurality of LED chips are disposed in at least one of the plurality of recesses. The light emitting device according to any one of claims 1 to 4, wherein the translucent adhesive contains a fluorescent substance. The light emitting device according to claim 5, wherein at least one light shielding portion is formed between adjacent LED chips in the translucent support.

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