JP6297935B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device having a light emitting element such as a light emitting diode.

  Conventionally, as an example of a light-emitting device in which a light-emitting element is hermetically accommodated, an insulating base made of ceramics such as an aluminum oxide sintered body, having a recess on the upper surface, and the light-emitting element mounted on the bottom surface of the recess; Some have a metal frame joined to the upper surface of the insulating substrate via a seal ring, and a transparent lid joined to the upper surface of the metal frame via a low-melting glass (see Patent Document 1). reference).

  However, when the transparent lid and the metal frame are joined with a low melting point glass or the like, the joining strength of the low melting point glass is low, so the thickness is thick and the rigidity is high so that no stress is applied to the bonding surface of the low melting point glass. There was a tendency to use metal frames.

  Therefore, in order to reduce the size of the light emitting device, a light emitting device having a configuration in which a transparent lid is bonded to the upper surface of an insulating base via a resin material has been considered.

JP 2004-253638 A

  However, since the resin material deteriorates when the resin is irradiated with ultraviolet rays generated by the light emitting element, it is difficult to maintain the sealing performance of the light emitting device.

A light-emitting device according to an aspect of the present invention includes an insulating base having a recess on the upper surface, a light-emitting element that emits ultraviolet light provided on the bottom surface of the recess, and a light-shielding film on the outer periphery of the lower surface. A transparent lid provided on the upper surface of the insulating base so as to close the recess, and the light shielding film of the transparent lid and the upper surface of the insulating base are joined by a resin material. The inner end of the resin material is located outside the inner side surface of the recess, and the inner end of the light shielding film is located inside the inner end of the resin material. It is characterized by.

In the light emitting device according to one aspect of the present invention, the light shielding film of the transparent lid and the upper surface of the insulating base are joined by a resin material, and the inner end of the resin material is outside the inner surface of the recess. Therefore, the ultraviolet ray generated by the light emitting element is not easily hit by the resin material, and the ultraviolet ray generated by the light emitting element and reflected by the upper surface of the transparent lid is shielded by the light shielding film and is reflected. It is possible to prevent the ultraviolet light from hitting the upper surface and the inner end of the resin material and to prevent the resin material from deteriorating. Therefore, the sealing property of the light emitting device can be maintained.

(A) has shown the top view of the light-emitting device in embodiment of this invention, (b) has shown the longitudinal cross-sectional view in AA of the light-emitting device shown by (a). (A) has shown the enlarged view of the part shown with the code | symbol B in the light-emitting device shown by FIG.1 (b), (b) is an expanded sectional view which shows the other example of (a). The broken line in (b) represents ultraviolet rays. (A), (b) is an expanded sectional view which shows the other example of Fig.2 (a). (A), (b) is an expanded sectional view which shows the other example of Fig.2 (a).

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1A and 1B, a light emitting device according to an embodiment of the present invention is bonded to an insulating substrate 1, a light emitting element 2 mounted on the insulating substrate 1, and the insulating substrate 1. The transparent lid 3 is included. Hereinafter, the insulating substrate 1 may be referred to as the substrate 1.

  1A and 1B, the light emitting device is provided in a virtual xyz space, and for the sake of convenience, the upward direction is the positive direction of the virtual z axis.

  The insulating base 1 is provided with a wiring conductor (not shown) inside or on the surface thereof.

  The insulating substrate 1 is made of, for example, a ceramic material and has a recess 11a on the upper surface. For example, when the insulating substrate 1 is made of a ceramic material, it is integrally formed by firing. In FIG. 1A, the concave portion 11a has a two-stage structure, and a second-stage concave portion narrower than the first step is formed at the bottom of the first-stage concave portion. The light-emitting element 2 is mounted on. Since the side surface of the second-stage concave portion is an inclined surface, the light emitted from the light emitting element 2 in the lateral direction is emitted upward, and the luminous efficiency in the upward direction is increased. It is preferable that the concave portion is formed narrow because the light source approaches the point light source and the optical design becomes easy.

  Further, the entire side surface of the recess 11a may be an inclined surface. Also in this case, there is an effect that the luminous efficiency in the upward direction is increased.

When the insulating substrate 1 is made of, for example, a ceramic material, examples thereof include an aluminum oxide (alumina: Al ₂ O ₃ ) sintered body, an aluminum nitride (AlN) sintered body, and the like. On the insulator 11, the above-described wiring conductor is formed.

If the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, it is suitable as a raw material powder of alumina (Al ₂ O ₃ ) and silica (SiO ₂ ), calcia (CaO), magnesia (MgO), or the like. An organic solvent and a solvent are added and mixed to form a slurry, which is formed into a sheet shape by a known doctor blade method or calendar roll method or the like to obtain a ceramic green sheet (hereinafter also referred to as a green sheet).

  Next, a conductor paste layer serving as a wiring conductor is formed to a thickness of about 10 μm to 20 μm at a predetermined position of the green sheet by screen printing or the like.

  The conductor paste is produced by kneading a metal powder having a high melting point such as tungsten (W), molybdenum (Mo), or molybdenum-manganese (Mo-Mn) alloy with an appropriate resin binder and solvent.

  Next, through holes to be the concave portions 11a are formed at predetermined positions of the green sheet by appropriate punching, and these green sheets are laminated and pressure-bonded as necessary to produce a laminated body. A large number of mother substrates are produced by firing at a high temperature.

When the insulating substrate 1 is made of an aluminum oxide sintered body, it is difficult to warp due to its high mechanical strength and has an appropriate thermal conductivity, so that the heat generated by the light emitting element 2 is transferred to the outside. It becomes easy to dissipate and is preferable in terms of mechanical strength, thermal conductivity and cost.

  The light emitting element 2 is, for example, a light emitting diode element, and emits light having a wavelength in the ultraviolet region (UV region), for example. The light emitting element 2 is provided on the bottom surface of the recess. The light emitting element 2 is electrically connected to the wiring conductor of the insulating base 1 described above at the bottom surface of the recess.

  As shown in FIG. 1 and FIG. 2A, the transparent lid 3 is provided with a light shielding film 5 on the outer peripheral portion of the lower surface, and the upper surface of the insulating substrate 1 so as to close the recess of the insulating substrate 1. Is provided.

As a material of the transparent lid 3, a glass material, quartz glass, or the like is used. Insulating substrates such as BK7 (manufactured by HOYA, linear thermal expansion coefficient is approximately 7.5 × 10 ⁻⁶ / ° C.), D263 (manufactured by Schott, linear thermal expansion coefficient is approximately 7.2 × 10 ⁻⁶ / ° C.) It is preferable to use a material having a thermal expansion coefficient close to 4 because the selection range of the resin material 4 to be bonded to the insulating substrate 1 is widened.

  In addition, in the light emitting device used in the wavelength range of 250 to 270 nm, which is a wavelength range used for sterilization, among ultraviolet rays, the transmittance is low when a glass material is used as the transparent lid 3. Therefore, it is preferable to use quartz glass, quartz crystal, and sapphire glass for the transparent lid 3. Further, in the case of the same thickness, quartz glass is more preferable because it has a deep ultraviolet transmittance higher than that of quartz or sapphire glass.

When the quartz glass transparent lid 3 is used for the insulating base 1 of the aluminum oxide sintered body, the thermal expansion coefficient of the aluminum oxide sintered body is generally about 7.2 × 10 ⁻⁶ / ° C. Yes,
Since the thermal expansion coefficient of quartz glass is as small as about 0.58 × 10 ⁻⁶ / ° C., the thermal stress applied to the resin material 4 is increased. Therefore, it is preferable to use the resin material 4 having a Young's modulus of less than 3 GPa. In this case, the stress due to the difference in thermal expansion between the insulating base 4 and the transparent lid 3 on the resin material 4 can be relaxed.

  The transparent lid 3 can be formed into a rectangular shape by using conventionally known dicing, laser cutting, or the like.

  In the figure, the corner portion is not chamfered, but by making each edge portion a C surface or an R surface, cracks from microcracks due to processing of the transparent lid 3 can be reduced. it can.

  As shown in FIG. 1, the light shielding film 5 is provided on the outer peripheral portion of the lower surface of the transparent lid 3. The light shielding film 5 may be made of any material that can shield ultraviolet rays, and examples thereof include CrO—Cr—CrO. The light shielding film 5 is formed by performing sputtering or the like on the transparent lid 3.

When a certain film is light in the ultraviolet region (with a wavelength of 200 nm to 300 nm) and the transmittance in the transmission region without the film is 100%, the transmittance of the film portion is less than 1% (preferably 0.1%). The film may be determined as the light shielding film 5 in the ultraviolet region.

  In the measurement of the transmittance of ultraviolet rays, a set jig having a hole through which light is transmitted is disposed only in the region where the light shielding film 5 is formed at the measurement site of the spectrophotometer, and the light shielding film 5 is formed. The transmittance is measured so that the measurement light does not enter other areas.

As shown in FIG. 1, the light shielding film 5 of the transparent lid 3 and the upper surface of the insulating base 1 are made of a resin material 4.
The inner end portion of the resin material 4 is located outside the inner surface of the recess 11a. For example, an epoxy resin may be used as the resin material 4.

  Further, as described above, in order to reduce the Young's modulus of the resin material 4 to less than 3 GPa, for example, a filler added to the epoxy resin to be used is added as an organic material powder having a small Young's modulus, and a known curing agent is added to the epoxy resin. A cured resin may be used. Such organic material powders include silicone rubber, silicone resin, polyethylene resin, methacrylic resin, crosslinked methacrylic resin, polystyrene resin, crosslinked polystyrene resin, ethylene-acrylic copolymer, polyethyl methacrylate resin, butyl acrylate resin, urethane. Soft fine particles such as resin are preferred.

  Further, as in the example shown in FIGS. 1 and 2, a light shielding film 5 is provided on the entire upper surface of the resin material 4. Thereby, it is possible to prevent the reflected ultraviolet light from hitting the upper surface of the resin material 4. Thereby, deterioration of the upper surface of the resin material 4 can be prevented.

  In the example shown in FIG. 2, only a cross section is shown, but the light shielding film 5 is formed in an annular shape as shown in FIG. 1, and covers the upper surface of the resin material 4 over the entire circumference of the recess 11a. ing. In this case, it is possible to prevent the reflected ultraviolet light from hitting the upper surface of the resin material 4 over the entire circumference of the recess 11a.

  If the resin paste used as the resin material 4 is formed on the upper surface of the insulating substrate 1 by screen printing, the transparent lid 3 is placed on the upper surface of the insulating substrate 1, kept at a predetermined temperature, and the resin paste is solidified. Good. Thereby, the transparent lid 3 and the insulating base 1 are bonded.

  Further, the resin paste that becomes the resin material 4 may be applied to the lower surface of the transparent lid 3 instead of the upper surface of the insulating substrate 1.

  The resin material 4 is generally deteriorated by ultraviolet rays generated by the light emitting element 2, but as described above, the inner end portion of the resin material 4 is located outside the inner side surface of the recess 11a. The ultraviolet rays generated by the light emitting element 2 do not directly hit the inner end of the resin material 4, and the light shielding film 5 of the transparent lid 3 and the upper surface of the insulating base are joined by the resin material 4. In addition, since the resin material 4 is covered with the light shielding film 5, the ultraviolet light generated by the light emitting element 2 and reflected by the upper surface of the transparent lid 3 is shielded by the light shielding film 5. It can prevent hitting the upper surface of the material 4 and can prevent the resin material 4 from deteriorating.

  Further, as in the example shown in FIG. 2A, the inner end of the light shielding film 5 is located on the inner side of the inner end of the resin material 4, so that the reflected ultraviolet rays are reflected by the resin material. It is possible to prevent the inner end of 4 from hitting diagonally. Thereby, deterioration of the edge part inside the resin material 4 can be prevented.

  Further, as in the example shown in FIG. 2B, the inner end of the light shielding film 5 is located on the outer side of the inner side surface of the recess 11a and is further on the inner side than the inner end of the resin material 4. Preferably it is located. In this case, as in FIG. 2A, the inner end of the light shielding film 5 is located on the inner side of the inner end of the resin material 4. Since the inner end of the light shielding film 5 is located outside the inner surface of the recess 11a as compared with FIG. It is possible to prevent the light emitted from the light emitting element 2a from being blocked by the light shielding film 5, and to allow good external irradiation.

2A and 2B, it is preferable that the outer end portion of the light shielding film 5 is positioned outside the outer end portion of the resin material 4. Accordingly, it is possible to prevent the ultraviolet rays from the outside and the ultraviolet rays irradiated by the light emitting element 2a and reflected from the outside of the light emitting device from being hit from the outside at the outer end portion of the resin material 4. Accordingly, it is possible to further prevent the deterioration of the outer end portion of the resin material 4.

  Moreover, it is preferable that the antireflection film 6 is provided on the lower surface of the transparent lid 3 as in the example shown in FIG. In this case, since it is possible to prevent the ultraviolet rays generated by the light emitting element 2 from being reflected on the lower surface of the transparent lid 3, the ultraviolet rays reflected by the lower surface of the transparent lid 3 are the inner end of the resin material 4. It can prevent hitting the part. Accordingly, it is possible to further prevent the deterioration of the inner end portion of the resin material 4.

  When the antireflection film 6 is provided on the lower surface of the transparent lid 3, the antireflection film 6 may be provided on the lower surface of the light shielding film 5 as in the example shown in FIG. In this case, the light shielding film 5 of the transparent lid 3 and the upper surface of the insulating substrate 1 are bonded via the resin material 4 and the antireflection film 6 sandwiched between the resin material 4 and the light shielding film 5. The Rukoto.

  Moreover, it is preferable that the antireflection film 6 is provided on the upper surface of the transparent lid 3 as in the example shown in FIG. In this case, since it is possible to prevent the ultraviolet rays generated by the light emitting element 2 from being reflected on the upper surface of the transparent lid 3, the ultraviolet rays reflected on the upper surface of the transparent lid 3 are the inner edges of the resin material 4. It is possible to further prevent hitting the part or the upper surface. Accordingly, it is possible to further prevent disassembly / discoloration of the upper surface or inner end of the resin material 4.

As a specific example of the antireflection film 6, for example, a film in which Al ₂ O ₃ , ZrO ₂ , and MgF ₂ are sequentially laminated from the transparent lid 3 side is used.

  Moreover, it is preferable that the convex part 12 is provided in the outer peripheral part of the upper surface of the insulation base | substrate 1 like the example shown to Fig.4 (a). In this case, it is possible to prevent ultraviolet rays coming from the outside of the light emitting device from hitting the outer end of the resin material 4 from an oblique direction. Therefore, decomposition / discoloration of the outer end of the resin material 4 can be further prevented.

  In addition, in the example shown in FIG. 4, although only the cross section is shown, the convex part 12 is formed in an annular shape like the resin material 4 shown in FIG. 1A, and extends over the entire circumference of the concave part 11a. Preferably it is formed. In this case, it is possible to prevent the ultraviolet rays coming from the outside of the light emitting device from hitting the outer end of the resin material 4 obliquely over the entire circumference of the outer periphery of the recess 11a. Therefore, decomposition / discoloration of the outer end of the resin material 4 can be further prevented.

  Further, as in the example shown in FIG. 4B, the upper surface of the insulating base 1 is preferably inclined so as to become lower from the inside toward the outside. In this case, since the gap between the insulating base 1 and the transparent lid 3 is reduced on the inner surface side of the insulating base 1, it is possible to prevent the ultraviolet rays from the light emitting element 2 a from hitting the inner end of the resin material 4. Can do. Therefore, decomposition / discoloration of the inner end of the resin material 4 can be further prevented.

DESCRIPTION OF SYMBOLS 1 Insulation base | substrate 2 Light emitting element 3 Transparent cover body 4 Resin material 5 Light shielding film

Claims (4)

An insulating substrate having a recess on the upper surface;
A light emitting element that emits ultraviolet rays , provided on the bottom surface of the recess;
A light shielding film is provided on the outer peripheral portion of the lower surface, and a transparent lid provided on the upper surface of the insulating base so as to close the concave portion,
The light shielding film of the transparent lid and the upper surface of the insulating base are joined with a resin material,
The inner end of the resin material is located outside the inner surface of the recess ,
An inner end of the light shielding film is located on an inner side than an inner end of the resin material . The end of the outer side of the light shielding film, the light-emitting device according to claim 1, characterized in that located on the outer side than the end portion of the outer side of the resin material.   The inner end of the light shielding film is located outside the inner surface of the recess.
  The light-emitting device according to claim 1 or 2. The light emitting device according to any one of claims 1 to 3, wherein an antireflection film is provided on at least one of an upper surface or a lower surface of the transparent lid.

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