JP2015162505A - Substrate for mounting light-emitting element and light-emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for mounting a light-emitting element and the light-emitting device using the same, capable of enhancing light emission intensity.SOLUTION: A substrate for mounting a light emitting element includes a base substrate part 3 having a mounting surface 1 of a light-emitting element and a frame part 5 arranged so as to enclose the mounting surface 1 on the base substrate part 3, both of which are constituted of an alumina ceramic sintered compact. In the frame part 5, an inner wall surface 5a on the mounting surface 1 side is formed as a smooth surface and an outer wall surface 5b on the side opposite to the mounting surface 1 is formed as an uneven surface whose surface roughness is larger than that of the inner wall surface 5b. The light-emitting device includes a light-emitting element 10 in a mounting part 1 of the substrate for mounting the light emitting element.

Description

  The present invention relates to a light-emitting element mounting substrate and a light-emitting device using the same.

  In recent years, from the viewpoint of energy saving and environmental conservation, LCD televisions and backlights for liquid crystal screens and LEDs (Light Emission Diodes) for general household lighting have been developed. Light-emitting devices using LEDs as light-emitting elements are attracting attention because they have many excellent features, such as about 10 times the life of fluorescent lamps and incandescent bulbs, and about 1/10 of the electricity bill.

  Conventionally, this type of light-emitting device has a configuration in which LED-type light-emitting elements are mounted on various substrates, and the light-emitting elements are connected to electrode patterns formed on the various substrates by wire bonding or bump mounting. Yes.

  Among them, it has higher thermal conductivity and mechanical strength, superior heat resistance and durability than synthetic resins used for conventional light-emitting element mounting substrates, and does not deteriorate even when exposed to ultraviolet rays for a long time. For this reason, attention has been paid to a light-emitting element mounting substrate based on alumina ceramics (see, for example, Patent Document 1).

  However, as shown in FIG. 6, in the light emitting device having the conventional structure, when the light emitting element mounting substrate 101 is downsized and the thickness of the frame body portion 105 is reduced, the light 109 emitted from the light emitting element 107 is obtained. There is a problem that a part of the light passes through the frame body part 105 from the inner wall surface 105a to the outer wall surface 105b, and the light emission intensity decreases.

International Publication No. 2011/037185 Pamphlet

  Accordingly, an object of the present invention is to provide a light emitting element mounting substrate capable of increasing the light emission intensity and a light emitting device using the same.

  The substrate for mounting a light emitting element of the present invention is composed of a sintered body made of alumina ceramics, and has a base part having a mounting surface of the light emitting element, and a frame part arranged so as to surround the mounting surface on the base part The frame body portion includes an inner wall surface on the mounting surface side as a smooth surface, and an outer wall surface opposite to the mounting surface on a surface rougher than the inner wall surface. It is characterized by a rough uneven surface.

  The light emitting device of the present invention is characterized in that a light emitting element is provided in the mounting portion of the light emitting element mounting substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the light emitting element mounting substrate which can make luminous intensity high, and a light-emitting device using the same can be obtained.

(A) is a perspective view which shows typically an example of the light emitting element mounting substrate of this embodiment, (b) is the sectional view on the AA line of FIG. It is an example of the other light emitting element mounting board | substrate of this embodiment, and is a cross-sectional schematic diagram which shows that the continuous location of the mounting surface and an inner wall surface has comprised the curved surface. An example of the other light emitting element mounting board | substrate of this embodiment is shown, and it is a cross-sectional schematic diagram which shows that the mounting surface is dented in hook shape. It is a cross-sectional schematic diagram which shows the light-emitting device of this embodiment. It is a schematic diagram which shows the manufacturing process of the light emitting element mounting substrate of this embodiment. It is a cross-sectional schematic diagram which shows typically an example of the conventional light emitting element mounting substrate.

  FIG. 1A is a perspective view schematically showing an example of the light emitting element mounting substrate of the present embodiment, and FIG. 1B is a cross-sectional view taken along line AA of FIG.

  The light emitting element mounting substrate of the present embodiment includes a base portion 3 having a mounting surface 1 for mounting a light emitting element, and a frame body portion 5 disposed so as to surround the mounting surface 1. Both the base body portion 3 and the frame body portion 5 are made of a sintered body made of alumina ceramics. Further, in this light emitting element mounting substrate, when the mounting surface 1 side of the frame 5 is the inner wall surface 5a and the surface opposite to the mounting surface 1 is the outer wall surface 5b, the inner wall surface 5a is a smooth surface. In addition, the outer wall surface 5b is an uneven surface having a rougher surface roughness than the inner wall surface 5a.

  According to the light emitting element mounting substrate of the present embodiment, the inner wall surface 5a of the frame body portion 5 is a smooth surface with small unevenness, and the outer wall surface 5b opposite to the inner wall surface 5a is an uneven surface with large surface roughness. Therefore, the inner wall surface 5a becomes the surface of the mirror, and the outer wall surface 5b, which is the back surface of the mirror, acts as if it is a silver film surface of the mirror, so that the light emitted in the frame 5 is reflected by the inner wall surface 5a. It becomes easy and the emitted light intensity can be raised in the frame 5. As a result, even if a glass film or a metal film is not formed on the inner wall surface 5a of the frame body part 5, a light emitting element mounting substrate having a light emission intensity equivalent to these can be obtained.

  In addition, since the light emitting element mounting substrate is made of alumina ceramics and has high mechanical strength such as the base portion 3 and the frame portion 5 constituting the substrate, the base portion 3 and the frame portion 5 have a high mechanical strength. Even if the thickness is reduced, it also has a surface that is less likely to be chipped or cracked. For this reason, since the transmission of light can be suppressed even if the thickness of the frame body portion 5 is thin, it is possible to maintain high reflection characteristics as a light emitting element mounting substrate.

  In this embodiment, being made of alumina ceramics means containing 90% by mass or more of alumina. Moreover, a smooth surface means that whose surface roughness is 0.5 μm or less, and an uneven surface means that whose surface roughness is 1.0 μm or more. That is, it is desirable that the smooth surface and the uneven surface have a difference of 0.5 μm or more in surface roughness. The surface roughness of the inner wall surface 5a and the outer wall surface 5b of the frame 5 can be obtained by measuring a piece obtained by cutting the light emitting element mounting substrate using a laser displacement meter.

  Further, in the light emitting element mounting substrate of the present embodiment, the irregular surface is formed to extend not only to the outer wall surface 5b of the frame body part 5 but also to the upper surface side of the frame body part 5 except for the inner wall surface 5a of the frame body part 5. May be. Thereby, the reflection characteristic of the light in the frame part 5 can be improved.

  Moreover, in the light emitting element mounting substrate of this embodiment, it is desirable that the corner portions C of the base body portion 3 and the frame body portion 5 are rounded. When the corner C is rounded in the light emitting element mounting substrate, it is possible to reduce chips and cracks that are likely to occur when the substrate is handled and hit against an object.

  FIG. 2 shows an example of another light emitting element mounting substrate according to this embodiment, and is a schematic cross-sectional view showing that a continuous portion between the mounting surface 1 and the inner wall surface 5a forms a curved surface.

  In the light emitting element mounting substrate according to the present embodiment, it is desirable that a continuous portion between the mounting surface 1 of the base portion 3 and the inner wall surface 5a of the frame portion 5 forms a curved surface. When the light-emitting element mounting substrate is viewed in a longitudinal section, the continuous portion of the mounting surface 1 and the inner wall surface 5a is not a curved surface, and the mounting surface 1 and the inner wall surface 5a are in contact with each other at a predetermined angle. In the case of a structure having a bent surface, the reflection of light around the bent surface is partially weakened.

  Further, when the continuous portion between the mounting surface 1 and the inner wall surface 5a is a bent surface, stress is applied to the base body portion 3 and the frame body portion 5 when the substrate is handled in a mounting process or when the substrate is assembled to a mother board or the like. When it is applied, the stress tends to concentrate on the joint portion of the base portion 3 and the frame portion 5. For this reason, cracks are likely to occur starting from the vicinity of the intersection between the base portion 3 and the frame portion 5.

  On the other hand, when the continuous part of the mounting surface 1 and the inner wall surface 5a forms a curved surface, the resistance against the stress applied to the frame body part 5 increases in the mounting process or the like, and the base body part 3 and the frame body Generation of cracks and chips starting from the vicinity of the intersection with the portion 5 can be reduced. In this case, it is desirable that the radius of the curved surface from the inner wall surface 5 a of the frame body portion 5 to the mounting surface 1 of the base body portion 3 is 20 μm or more. This is because, if the radius of the curved surface formed by the inner wall surface 5a of the frame body portion 5 and the mounting surface 1 of the base body portion 3 is less than 20 μm, the effect of preventing cracks is not sufficient because it is close to a bent state.

  FIG. 3 shows an example of another light emitting element mounting substrate according to the present embodiment, and is a schematic cross-sectional view showing that the mounting surface is recessed in a bowl shape. The structure in which the light emitting element mounting substrate of this embodiment is further changed locally will be described. The mounting surface 1 is preferably recessed in a bowl shape. In the light emitting element mounting substrate described above, the continuous portion of the mounting surface 1 and the inner wall surface 5a has a curved surface. In addition, the mounting surface 1 is recessed in a bowl shape, When the surface extending from the wall surface 5a to the central region of the mounting surface 1 has a curved surface and a concave shape, the area of the mounting surface 1 becomes larger than when the mounting surface 1 is a flat surface. 5 can increase the light reflection surface, so that the light emission intensity can be increased as the light emitting element mounting substrate. Even in this case, the surface of the base portion 3 opposite to the mounting surface 1 can mount and connect the light emitting element mounting substrate to a mother board, a metal base or the like at a uniform height, thereby obtaining high mounting reliability. It is desirable that it is planar because it can be used.

  In addition, the base body portion 3 and the frame body portion 5 in the present embodiment may be colored in a color tone such as black, dark blue, and gray as long as the light reflection characteristics (light emission intensity) can be maintained.

  In the light emitting element mounting substrate of the present embodiment, for example, as shown in FIG. 1A, the frame body portion 5 is formed such that the inner wall surface 5a has a larger opening diameter on the upper side. It is desirable. When the inner wall surface 5a of the frame body part 5 has the above structure, light can be widely reflected from the opening 5o of the mortar-shaped frame body part 5.

  FIG. 4 is a schematic cross-sectional view showing the light emitting device of this embodiment. The light emitting device of this embodiment is characterized in that a light emitting element 10 is provided on the mounting surface 1 of the light emitting element mounting substrate described above. In this light emitting device, the frame portion 5 of the light emitting element mounting substrate constituting the light emitting device has an inner wall surface 5a on the mounting surface 1 side as a smooth surface, and an outer wall surface 5b opposite to the mounting surface 1 from the inner wall surface 5a. Is also an uneven surface with a rough surface. With such a configuration, even when the inner wall surface 5b of the frame body part 5 does not have a light reflection film such as a glass film or a metal film, it exhibits high light emission.

  In addition, the light emitting element mounting substrate of this embodiment is provided with a conductor layer for connecting to the light emitting element or an external power source on the surface or inside thereof as necessary.

  Next, a method for manufacturing the light emitting element mounting substrate and the light emitting device of the present embodiment will be described. FIG. 5 is a schematic view showing a manufacturing process of the light emitting element mounting substrate of the present embodiment.

  First, as shown in FIG. 5 (a), a green sheet 21 for forming the base portion 3 and the frame portion 5 is prepared, and this is projected on one surface as shown in FIG. 5 (b). The green sheet 21 is pressed by a mold having the part 23. Thus, a molded body 27 in which the portion corresponding to the convex portion 23 becomes the concave portion 25 can be formed. In this case, it is desirable that the surface roughness of the convex portion 23 in contact with the green sheet 21 of the mold used in the pressing process is 0.5 μm or less. Further, the mold may be an integral type having convex portions 23 at a plurality of locations.

  Next, as shown in FIG. 5C, the mother body 31 having a plurality of recesses 25 (corresponding to the openings 5o) is formed by firing the molded body 27 under a predetermined temperature condition.

  Next, as shown in FIG. 5D, snap grooves 33 are formed on the surface between the recesses 25 of the mother substrate 31. Although the groove 33 depends on the thickness of the mother substrate 31, it is desirable to form the groove 33 at a ratio of 5 to 20 when the thickness of the mother substrate 31 is 100. For example, when the thickness of the mother substrate 31 is 0.7 mm, the depth of the groove 33 is preferably 0.035 to 0.140 mm. If the depth of the groove 33 is set so as to have the above ratio and dimensions, the frame portion 5 and the base portion 3 can be rounded at the corners C, resulting in cracks and chipping. Can be suppressed. For the processing of the groove 33, it is preferable to use laser processing for the purpose of reducing the surface roughness. If the breakability is poor, a similar groove 33 may be provided at a position facing the groove 33 of the mother substrate 31.

  Next, as shown in FIG. 5 (e), the mother substrate 31 is split or mechanically broken along the groove 33 so that the broken portion is pressed by the convex portion 23 of the mold. The surface roughness is larger than the surface and the surface of the groove 33 processed by laser processing. Thereby, the light emitting element mounting substrate shown in FIGS. 1A and 1B can be obtained (FIG. 5F).

  In addition, the shape where the continuous location of the mounting surface 1 of the base | substrate part 3 of the light emitting element mounting substrate and the inner wall face 5a of the frame body part 5 forms the curved surface, or the shape in which the mounting surface 1 is dented in bowl shape. Can be produced by changing the shape of the mold.

  After mixing 90% by mass of alumina powder and 10% by mass of glass powder, 19% by mass of acrylic binder as organic binder, 3% by mass of paraffin wax as wax, and toluene as organic solvent were mixed. After preparing the slurry, a green sheet having an average thickness of 0.5 mm was prepared by a doctor blade method.

  Next, using the metal mold | die which has a convex part, it heat-pressed at the temperature of 80 degreeC, and then baked for 1 hour at the temperature of 1300-1500 degreeC in air | atmosphere, and produced the mother board | substrate. The concave portions formed in the fired mother substrate each had a mortar shape in which the inner wall surface of the portion surrounding the mounting surface increased the opening diameter upward.

Next, grooves were formed by laser processing between the recesses of the manufactured mother substrate, and then divided into individual pieces by hand to obtain a light emitting element mounting substrate. Among the laser processed samples, Sample No. No. No. No. 5 processed with a laser output of 60% was used. In all the samples other than 2, the upper surface of the frame portion was rounded. For the groove processing by laser processing, sample no. 2 to 4 are only on the frame body side.
About 5-7, both the base | substrate part side and the frame part side were performed. The depth of each groove was about 0.03 mm. In this case, sample no. As for 2-4, the uneven surface was formed in the outer wall surface except the upper surface vicinity of the frame part. Sample No. In 5-7, the uneven surface was formed in the central region of the outer wall surface.

  The obtained light emitting element mounting substrate had a planar area of 3 mm × 3 mm and a thickness of the frame body (thickness at the height of the mounting portion on the surface of the base body) was 0.25 mm. The thickness of the area of the mounting surface of the base body was 0.15 mm.

  First, the obtained light emitting element mounting substrate was cut, and the surface roughness of the inner wall surface and the outer wall surface of the frame portion was measured using a laser displacement meter.

  Further, an LED element is mounted on the mounting surface of the obtained light emitting element mounting substrate, and this light emitting element is connected to a power source with a conductive wire, and the light emitting intensity of the light emitting element mounting substrate of the comparative example (sample No. 1) is 100. The emission intensity ratio of each sample was calculated as%.

  Further, the obtained light emitting element mounting substrate was subjected to a drop test, and the state of damage of the light emitting element mounting substrate was observed. The damaged state after the drop test is that, for example, in the observation at a magnification of 20 to 50, scratches or chips were found at the corners of the light emitting element mounting substrate. Moreover, the crack which generate | occur | produced in the interface of a base | substrate part and a frame part was also confirmed. The drop test was performed using the natural drop test method of JIS C0044-1995. In this case, the height of the drop was 1 m, and the number of drops was two. The number of samples was 20.

  As a comparative example, two green sheets having a thickness of 0.3 mm are prepared, one of which is used for the frame body, and the opening portion is punched out using a mold, and then the second green sheet The laminated body was produced by stacking on a sheet and applying pressure and heating for integration. Next, this laminate was cut with a cutter so that the individual pieces became a light emitting element mounting substrate after firing, and fired under the same conditions as described above, and the same evaluation was performed. In the vicinity of the upper surface of the frame portion of this sample, the surface when the laminate was cut was left as it was, and the surface was square.

  In Table 1, the construction method using a mold having convex portions was described as pressure molding, and the construction method for producing a sample of a comparative example was described as laminate molding. In addition, a shape in which a continuous portion between the mounting surface and the inner wall surface forms a curved surface is described as a curved surface, and a shape in which the mounting surface and the inner wall surface are in contact with each other with a predetermined angle is described as a corner.

  As can be seen from Table 1, the sample No. 1 has a smooth surface on the inner wall surface of the frame and an uneven surface on the outer wall surface. In Nos. 2 to 7, the emission intensity ratio when the sample of the comparative example (sample No. 1) was 100 was 113 or more. In addition, these samples can be confirmed as damage to the corners of the substrate at 1 or less of 20 pieces, and the number of cracks seen at the interface between the base portion and the frame portion is 2 or less of 20 pieces. It was.

  Among these samples, the samples (samples Nos. 3, 4, 6, and 7) having a curved portion at the continuous portion between the mounting surface and the inner wall surface have an emission intensity ratio of 114 or more, and the base portion and the frame portion. The number of cracks observed at the interface was 1 or less out of 20.

  In addition, the sample No. with the mounting surface recessed in a bowl shape. In Nos. 4 and 7, there was no sample in which a crack occurred at the interface between the base portion and the frame portion.

1... Mounting surface 3. ····· Light emitting element 21 ······ Green sheet 23 ··· Convex portion 25 ··· Concavity portion 27 ··· Molded body 31 ··· Mother board 33 ・ ・ ・ ・ ・ ・ Groove

Claims (6)

  A substrate for light emitting element mounting, which is composed of a sintered body made of alumina ceramics and includes a base portion having a mounting surface for the light emitting element and a frame portion disposed on the base portion so as to surround the mounting surface. The frame portion has an inner wall surface on the mounting surface side as a smooth surface, and an outer wall surface opposite to the mounting surface as an uneven surface having a surface roughness rougher than that of the inner wall surface. A light-emitting element mounting substrate.   The light emitting element mounting substrate according to claim 1, wherein a continuous portion between the mounting surface and the inner wall surface forms a curved surface.   The light emitting element mounting substrate according to claim 1, wherein corners of the base portion and the frame portion are rounded.   The light emitting element mounting substrate according to any one of claims 1 to 3, wherein the frame body portion is formed such that the inner wall surface has an opening diameter larger on the upper side.   The light-emitting element mounting substrate according to claim 1, wherein the mounting surface is recessed in a bowl shape.   A light emitting device comprising a light emitting element on the mounting surface of the light emitting element mounting substrate according to claim 1.

Images