JP5119610B2 - Light emitting diode - Google Patents

Description

  The present invention relates to a light emitting diode using a semiconductor light emitting element, and more particularly to a light emitting diode capable of high output and excellent in heat resistance and electrostatic withstand voltage.

  Light emitting diodes (hereinafter referred to as LEDs) using semiconductor light emitting elements are widely used in light sources for liquid crystal backlights such as mobile phones, flashlights, and the like. In particular, in recent years, light output has been advanced, and application to various lighting devices such as indoor lighting and car headlights is also being put into practical use.

  Such an LED has a structure in which a lead terminal for energization is provided in a package on which a semiconductor light emitting element is mounted, and is further sealed with a resin or the like to protect the semiconductor light emitting element or wire. It is common. As the package, a resin package that is easy to process and excellent in productivity is mainly used. However, problems such as color change with light or heat from the semiconductor light emitting element at high output are likely to occur. Therefore, the durability of the semiconductor light emitting device has become a problem, for example, the semiconductor light emitting device has become unusable although the lifetime has not yet been exhausted.

  In order to solve such a problem, a light emitting diode using a ceramic package or a metal package is also known. These may be limited in shape as compared to resin, or may be difficult to process, but they are suitable for high-power LEDs because of excellent durability against heat and light.

  However, since the ceramic package is a sintered body, it has a property that light is easily transmitted as compared with a resin package having the same thickness. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-356344, a structure in which light is not leaked to the outside by providing a metal layer on a resin package has been studied.

JP 2004-356344 A

  As described above, by providing a metal layer in the ceramic package, light from the semiconductor light emitting element can be reflected well and efficiently emitted to the outside, but the adhesion between the metal and the resin is not good, Problems of peeling such as the sealing resin being easily peeled off easily occur. If a gap is generated between the package and the sealing resin, moisture or the like easily enters from the portion, which may cause discoloration / deterioration of an internal semiconductor light emitting element, a wire, a metal layer, and the like. In particular, the metal layer may be colored due to deterioration to cause problems such as a change in emission color and a decrease in luminance. Furthermore, when a fluorescent member is included in the sealing resin, the optical path may be caused when the peeling of the sealing resin causes deterioration of the fluorescent member or when another member such as an air layer is present at the interface due to the peeling. Problems such as a shift in color tone due to a change in length or a change in output over time may occur.

  In addition, although the metal package does not transmit light from the package itself, it has low adhesion to the sealing resin. Occurs.

  Accordingly, an object of the present invention is to provide a light emitting diode that uses a ceramic package or a metal package and has high brightness and is not easily deteriorated.

In order to achieve the above object, a light emitting diode according to the present invention includes a ceramic package having a recess having a side surface and a bottom surface and having an upper surface as an opening, and the side surface of the recess is made of ceramic. A light-emitting device in which an element is placed and a recess is filled with a sealing member, and has a glass layer continuous from the side surface to the upper surface of the recess, the glass layer containing a pigment, and the upper glass layer Protrudes from the upper surface of the package.

  Thereby, the color purity of the luminescent color can be improved.

  The pigment preferably contains at least two kinds of pigments having different chromaticities. This makes it possible to express a color that is difficult to express with light in a full-color display or the like.

  Moreover, it is preferable that the upper surface around the opening part of a recessed part is colored black, or the black member is distribute | arranged to the package. Thereby, contrast can be improved.

  The package is preferably made of ceramic. Thereby, it is possible to suppress the light from being transmitted from the side surface of the concave portion of the package and to improve the color purity of the emitted color.

  With the light emitting diode according to the present invention, it is possible to obtain a light emitting diode which is high in output and hardly deteriorates and has excellent color purity. Furthermore, it can be set as the light emitting diode which can improve contrast, such as a display.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the light emitting diode for embodying the technical idea of the present invention, and the present invention does not limit the light emitting diode to the following.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. Hereinafter, the light emitting diode according to the present embodiment will be described with reference to the drawings.

  1A is a perspective view of a light emitting diode 100 according to the present embodiment, FIG. 1B is a plan view of FIG. 1A viewed from the light emitting surface (upper surface) side, and FIG. 1C is a cross-sectional view taken along the line XX ′ of FIG. It is sectional drawing. The package 101 of this embodiment is made of ceramic, and a cathode mark 107 is provided on the upper surface of the package, so that the polarity can be discriminated. And it has the recessed part which has a side surface and a bottom face and has an upper surface as an opening part, and is arrange | positioned so that the electrically-conductive member 102 may be exposed to the bottom face of a recessed part. The conductive member 102 is also exposed on the back surface of the package and is provided so as to be continuous inside the package. Thereby, it functions as a conductor wiring of the semiconductor light emitting element 103 mounted on the package. The semiconductor light emitting device 103 and the Zener diode 108 are fixed on the conductive member by a joining member such as resin or metal paste, and the semiconductor electrode and the z electrode of the Zener diode are electrically connected to the conductive member by the wire 104. is doing. Further, a sealing member 105 such as a resin is provided inside the recess so as to cover them. And the package of this form has the glass layer 106 in the side surface of a recessed part, This glass layer 106 contains the pigment, It is characterized by the above-mentioned.

  In the present invention, the color purity can be improved by including a pigment in the glass layer on the side surface of the concave portion. For example, when a semiconductor light emitting element capable of emitting blue light is used, the color purity at the time of light emission can be improved by using a blue pigment.

  Further, by providing the glass layer 106 on the side surface of the recess, light transmission can be suppressed and light can be efficiently reflected as compared with the case where the ceramic is exposed. Further, since the pigment is contained in the glass layer, the wettability of the side surface of the concave portion can be made higher than that of glass alone, so that the adhesion with the sealing member 105 provided in the concave portion is improved. Therefore, it is possible to prevent moisture and the like from entering and hardly change with time.

Hereinafter, each configuration of the present invention will be described.
(Pigment)
Various pigment materials can be selected according to the purpose. For example, examples of the red pigment include those containing CdSe, Fe ₂ O ₃ , MnAl, SnCr, Au, and the like as components. As the green pigment, it can be mentioned those containing such _Cr 3 _O 4, TiO ₂ as a component. Examples of the blue pigment include those containing CoAl ₂ O ₄ , CoO, Co ₂ SnO _{4, and the} like as components. A yellow pigment can also be used to improve the color purity of yellow, which is one of the three primary colors. These can be used by mixing them with the red, blue and green pigments. Examples of the yellow pigment include those containing PbCrO ₄ , CdS, FeO (OH) and the like as components.

  The pigment is synthesized in a gas phase, a liquid phase, or a solid phase so as to have a desired composition, and finally obtained by firing at a high temperature. Thereafter, a desired particle size is obtained through a pulverization step, and any particle size can be selected. It is preferably 2 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less. When the particle diameter of the pigment is smaller than the film thickness of the glass layer, the flatness is improved, and therefore, it is possible to suppress a decrease in light collecting property due to the inclination of the side wall of the package recess. Further, when the pigment particle size is larger than the film thickness of the glass layer, the scattering property can be improved. Further, since the pigment protrudes from the glass layer, the contact area with the sealing member is increased, and an anchor effect (also referred to as a throwing effect or a fastener effect) is also obtained, so that the adhesion with the sealing member can be improved. it can. Thereby, it can be set as the light emitting diode excellent in reliability.

  The particle size distribution of the pigment is preferably small, and thereby, chromaticity unevenness can be reduced. You may classify as needed. Further, the mixing amount may be an amount that can be uniformly mixed as a whole, and can be appropriately selected in consideration of the chromaticity and particle size of the pigment, the emission wavelength from the light emitting element, and the like.

(Glass layer)
The glass layer is preferably provided up to at least a position higher than the height of the semiconductor light emitting element among the side surfaces of the recess. For example, as shown in FIG. Can be provided. Thereby, when attaching members, such as a lens, a filter, and a mask, to the uppermost part, the effect that it becomes easy to position is acquired. Alternatively, as shown in FIG. 1C, the glass layer 106a can be provided not only on the side surface of the recess but also on the upper surface of the package. Thus, by providing a glass layer so that it may continue from the side surface of a recessed part and may cover two surfaces, the adhesiveness of a glass layer and a package can be improved and it can be made hard to peel. Furthermore, the glass layer can be provided not only on the side surface of the recess but also on the bottom surface of the recess. In that case, it is possible to provide a glass layer only in a desired region by masking the mounting region such as a semiconductor light emitting element and a Zener diode and the bonding region of the conductive wire and removing the mask after forming the glass layer. It becomes. Alternatively, a glass layer having a desired shape can be formed in advance with a transfer sheet or the like. Thus, by providing a glass layer not only on the side but also on the bottom, color purity can be further improved.

  In FIG. 1, one type of semiconductor light-emitting element is mounted. For example, when one semiconductor light-emitting element capable of emitting red, blue, and green is mounted one by one, a region close to each of the semiconductor light-emitting elements is mounted. A pigment having a color tone corresponding to the luminescent color can be provided on the side surface. By doing in this way, each color purity can be improved.

  The glass layer as described above may not have the same film thickness over the entire region. For example, as shown in FIG. 1C (a), the glass layer 106a provided to extend on the upper surface of the package is away from the recess. Therefore, the film thickness can be reduced. By doing in this way, since the upper surface of the package is not a flat surface but only a portion of the glass layer 106a is projected, the ball feeder (part feeder) in the work process such as sorting (classification), taping, and packing is used. At the time of conveyance, the area in contact with the apparatus is very small with the glass layer 106a, so that the contact resistance is small and the conveyance property is improved. In addition, when recognizing an image in the work process, the light illuminated on the glass layer is reflected in the same shape as the opening (ring shape in FIG. 1A), so that the contrast is increased and the identification becomes easy.

  Further, as shown in FIG. 1C (b), the film thickness can be increased in the vicinity of the interface with the bottom surface of the recess. As a result, air bubbles are less likely to be mixed between the package and the glass layer, and the adhesion of the glass layer can be improved, thereby making it easier to prevent intrusion of moisture and the like.

  As shown in FIG. 3A, the uppermost ceramic layer 301a of the laminated ceramic package is provided with a protruding portion 301a-1 that protrudes to the inside of the recess, and is also provided on the end surface and the lower surface of the protruding portion. can do. By doing so, as shown in FIG. 3A (a), the film thickness of the glass layer 306c formed in the vicinity of the interface between the uppermost ceramic layer 301a and the ceramic layer 301b below it is set to other regions. Can be thicker. This portion is prone to structural problems such as bubbles that tend to enter when sealing resin or the like is filled. However, a thick glass layer 306 is provided to fill a narrow region on the lower surface of the protrusion 301a-1. As a result, bubbles can be prevented from entering when the sealing resin is filled. When bubbles enter, light may be irregularly reflected and variations in optical characteristics may occur, but such a problem can be avoided.

  As will be described later, the glass layer may be provided before firing the ceramic package and fired together with the package, or may be provided in the recessed portion of the package after firing. In the case of firing together with the package, the pigment contained in the glass layer needs to be able to withstand the firing temperature, and a pigment that has a desired color after firing is used. In addition, as a method for providing the glass layer, in the case of a ceramic package, a generally known method such as spray coating, print coating, thermal transfer, or the like can be used before and after firing. In addition, as a method of providing a glass layer before baking, it demonstrates with the formation method of the following packages. Further, in the case of a metal package, it can be provided on the metal constituting the side surface of the recess by a method such as spray coating, printing coating, or transfer. Alternatively, the glass layer can be formed as a separate member from the metal package and bonded to the package. For example, pigment-containing glass can be easily formed by forming a cylindrical shape and bonding it to a metal package.

  The specific material of the glass layer can be appropriately selected as desired, but when it is formed before firing the ceramic package, a material that can withstand the firing temperature is preferable. In addition to the pigment, a flux or the like may be added. For example, when using a pigment that does not easily develop a desired color at a high temperature, it can be obtained by adding Pb and lowering the melting point.

(package)
The package of this embodiment can be made into a package with high heat resistance by using ceramic as a material for the insulating member. The ceramic is preferably, for example, alumina, aluminum nitride, mullite, silicon carbide, or silicon nitride. Specifically, 90 to 96% by weight of the raw material powder is alumina, and 4 to 10% by weight of clay, talc, magnesia, calcia, silica and the like are added as sintering aids and sintered in a temperature range of 1500 to 1700 ° C. 40-60% by weight of the sintered ceramic and raw material powder is alumina, and 60-40% by weight of borosilicate glass, cordierite, forsterite, mullite, etc. are added as a sintering aid in the temperature range of 800-1200 ° C. A sintered ceramic substrate can be used. In addition, by using aluminum nitride as a ceramic material, a support with high heat dissipation and high flatness of a mounting surface on which a semiconductor element is disposed can be obtained. Since the flatness of the mounting surface is high, the mounting accuracy of the semiconductor light emitting element can be improved.

  A ceramic green sheet obtained by molding a ceramic powder and a material obtained by mixing a binder resin into a sheet shape is laminated and fired to obtain a package having a desired shape. At this time, by forming and stacking through holes of various sizes on the ceramic green sheet, a package having a recess can be obtained. The metal underlayer disposed in such a package is fired by applying a conductive paste containing fine particles of a refractory metal such as tungsten or molybdenum in a predetermined pattern at an unfired ceramic green sheet stage. Can be obtained. Furthermore, after firing the ceramic green sheet, nickel, gold, or silver can be plated in order on the pre-formed base layer to form a metal member or conductive member disposed in the recess. It is preferable to arrange silver having a high reflectance with respect to light from the semiconductor light emitting element on the outermost surface.

  As described above, the package made of ceramic can be formed by forming the conductive member on a previously fired ceramic plate, in addition to integrally forming the conductive member and the insulating portion.

  Here, a manufacturing method for forming the glass layer before firing the ceramic package will be described with reference to FIG. FIG. 3B is a cross-sectional view showing the ceramic green sheets 301a, 302b, 301c, and 301d to be laminated. Except for the lowermost ceramic green sheet 301d that becomes the bottom of the recess, through holes are formed to form the recess. Yes. And glass layer 306a ', 306b', 306c 'is provided in the end surface of the ceramic green sheet used as a side surface of a recessed part, respectively. In order to provide a glass layer on such an end face, the glass layer can be obtained by a method of sucking from below the ceramic green sheet after screen printing. The pigmented ceramic sheet thus obtained is laminated as shown in FIG. 3C to form a laminated structure 300 ′, and then fired to obtain a package 300 as shown in FIG. 3D. In the stage before firing, each glass layer has a shape as separated as shown in FIG. 3C, but the glass layers softened by the heat during firing are fused to have a smooth surface as shown in FIG. 3D. Become.

  In FIG. 3A, the uppermost ceramic layer 301a has a protruding portion 301a-1, but in order to provide a glass layer also on the lower surface of the protruding portion, a ceramic green sheet 301a is formed like the glass layer 306a in FIG. 3B. It can be obtained by extending from the upper surface to the lower surface. In order to provide the glass layer up to the lower surface side of the ceramic green sheet, it can be easily obtained by adjusting the above-mentioned suction conditions.

  In addition, as the metal package, materials such as aluminum, nickel, kovar, iron, and a clad product (a laminate of dissimilar metals. For example, iron + copper) can be used.

(Black member)
FIG. 4 shows a light emitting diode in which a black member 409 is provided on the upper surface of the ceramic package 101 shown in FIG. 1B. The black member is not only provided on the upper surface of the package, but the package itself may be black. The black member is preferably pure black for improving the contrast, but any other black color can be used. Specifically, chromium oxide, zirconium oxide, titanium oxide, or the like can be used. These black member raw materials can be provided by mixing in a ceramic sheet before firing, printing, transferring, or applying after firing. By providing such a black member, contrast of a display or the like can be improved. At this time, when a transfer sheet or the like is used, the glass layer 106a also protrudes from the upper surface of the package as shown in FIG. Is reflected in the same shape as the opening (ring shape in FIG. 1A), so that the contrast is increased and identification becomes easy. For this reason, positioning accuracy at the time of mounting or transfer sheet pasting is improved, and displacement of the transfer sheet in the lateral direction can be suppressed during softening during firing.

(Semiconductor light emitting device)
Examples of the semiconductor light emitting device in this embodiment include those using various semiconductors such as ZnSe and GaN. However, when a light emitting diode having a fluorescent material is used, a short wavelength capable of efficiently exciting the fluorescent material emits light. possible nitride semiconductor _{(in X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is preferably exemplified. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition to such a light-emitting element, a light-receiving element, a protective element (for example, a Zener diode or a capacitor) that protects these semiconductor elements from destruction due to overvoltage, or a combination thereof can also be used.

  As shown in FIG. 1, in the semiconductor light emitting device, the p electrode and the n electrode of the semiconductor light emitting device are connected to the conductive member of the package using wires. This is an example when the substrate of the semiconductor light emitting device is insulative. However, when a conductive substrate is used, it is connected to one of the electrodes using a wire, and the conductive substrate is connected with a conductive adhesive member. It connects with the conductive member of a package. In FIG. 1B, the Zener diode is joined on the conductive member with a conductive adhesive member. In addition, when an insulating substrate is used, the electrode formation surface (semiconductor layer side) faces down, and the conductive wiring of the support is electrically and mechanically connected via a conductive material called bump (for example, gold or solder). Can be connected to. In addition, they can be connected via an auxiliary member called a submount.

  The adhesive member for fixing the semiconductor light emitting element to the package is, for example, a conductive adhesive such as gold paste or silver paste, or at least selected from Au, Ag, Bi, Cu, In, Pb, Sn, and Zn. A eutectic material containing one kind (for example, Au—Sn) or a brazing material containing at least one kind selected from Au and Ag can be used. By using an adhesive containing such a metal material, the electrode disposed on the back surface of the semiconductor element and the conductor wiring of the support are electrically connected, or heat dissipation from the semiconductor element is improved. be able to. In addition, a translucent resin such as an epoxy resin or a silicone resin can be used. In FIG. 1, the semiconductor light emitting element is provided on the conductive member, but it may be bonded to a package other than the conductive member, that is, the package.

(Sealing member)
The sealing member 105 in this embodiment is a member that protects a semiconductor light emitting element element or wire placed in the recess from dust, moisture, external force, or the like. Examples of the material for the sealing member include silicone resin, epoxy resin, and urea resin. The sealing member can contain various materials such as a colorant, a light stabilizer, and a fluorescent material as desired. Specifically, colorants such as pigments and dyes are included for the purpose of cutting unnecessary wavelengths according to the light emission wavelength and light reception wavelength of the semiconductor light emitting element.

  The filling amount of the sealing member may be an amount that covers a protective element such as a semiconductor light emitting element or a Zener diode, a conductive wire, or the like. In FIG. 1, the sealing member 105 is filled until it reaches the lower surface of the uppermost layer of the laminated ceramic package. However, the sealing member can be filled up to the uppermost layer of the ceramic layer. In particular, by controlling the height of the glass layer formed on the upper surface of the package, the sealing member can be made difficult to flow out, the amount of the sealing member can be easily controlled, and the optical characteristics are stabilized. Furthermore, since the flat surface on the upper surface of the sealing member can be enlarged, the light distribution characteristics can be easily controlled.

  The fluorescent material that can be contained in the sealing member is for converting light of the semiconductor light emitting element, and converting the light from the light emitting element to a longer wavelength is more efficient than converting the light to a shorter wavelength. . When the light from the light-emitting element is high-energy short-wavelength visible light, an yttrium-aluminum-garnet-based phosphor (hereinafter referred to as “YAG: Ce”), which is a kind of aluminum oxide-based phosphor, is preferably used. Used. The YAG: Ce phosphor absorbs a part of the blue light from the LED chip depending on its content and emits a yellow light that is a complementary color. Therefore, a high output light emitting diode that emits a white mixed light is used. It can be formed relatively easily.

  The light emitting diode according to the present invention has high light extraction efficiency and high color purity. Therefore, more brilliant light emission can be obtained. Further, since the black color purity that cannot be expressed by light in a display device capable of full color display can be improved, the display device can be used as a display device having excellent color reproducibility.

FIG. 1A is a perspective view showing a light emitting diode according to the present invention. FIG. 1B is a plan view of the light emitting diode of FIG. 1A. 1C is a cross-sectional view taken along the line X-X ′ of the light emitting diode of FIG. 1B. 1C (a) and 1C (b) are partial enlarged views of FIG. 1C. FIG. 2 is a cross-sectional view showing a light emitting diode according to the present invention. FIG. 3A is a cross-sectional view showing a light emitting diode according to the present invention. FIG. 3A (a) is a partially enlarged view of FIG. 3A. FIG. 3B is a cross-sectional view for explaining the manufacturing process of FIG. 3A. FIG. 3C is a cross-sectional view for explaining the manufacturing process of FIG. 3A and is a cross-sectional view after stacking the layers in FIG. 3B. 3D is a cross-sectional view for explaining the manufacturing process of FIG. 3A, and is a cross-sectional view after sintering in FIG. 3C. FIG. 4 is a plan view showing a light emitting diode according to the present invention.

Explanation of symbols

100, 200, 300, 400... Light emitting diode 101, 301... Package 301 ′... Laminated structure 301a, 301b, 301c, 301d. Layer protrusions 301a ′, 301b ′, 301c ′, 301d ′,..., Ceramic green sheet 102, conductive member 103, semiconductor light emitting element 104, conductive wire 105, sealing member 106 106a, 106b, 206, 306 ... Glass layers 306a ', 306b', 306c '... Glass layer 107 before firing 107 ... Cathode mark 108 ... Zener diode

Claims (3)

A ceramic package having a recess having a side surface and a bottom surface and having an upper surface as an opening, and a light emitting device in which a semiconductor light emitting element is mounted on the bottom surface of the recess, and a sealing member is filled in the recess,
Side surface of the concave portion is a ceramic having a glass layer which is continuous from the side surface to the upper surface, the glass layer contains a pigment, the glass layer of the top surface is characterized by protruding from the package top surface Light emitting diode.   The light emitting diode according to claim 1, wherein the pigment includes at least two types of pigments having different chromaticities.   3. The light-emitting diode according to claim 1, wherein the package has a black upper surface around the opening of the concave portion or a black member. 4.

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