Source: https://patents.google.com/patent/US20090122554A1/en
Timestamp: 2019-02-18 23:41:28
Document Index: 682453230

Matched Legal Cases: ['arts 6', 'art\n29', 'art\n50', 'art 29', 'art 29', 'art 49', 'art 49', 'art 52', 'art 53', 'art 52', 'art 52']

US20090122554A1 - Light-emitting element mounting substrate and manufacturing method thereof, light-emitting element module and manufacturing method thereof, display device, lighting device, and traffic light - Google Patents
US20090122554A1
US20090122554A1 US12/325,113 US32511308A US2009122554A1 US 20090122554 A1 US20090122554 A1 US 20090122554A1 US 32511308 A US32511308 A US 32511308A US 2009122554 A1 US2009122554 A1 US 2009122554A1
US12/325,113
US7866853B2 (en
2004-11-19 Priority to JP2004-336132 priority Critical
2004-11-19 Priority to JP2004336132A priority patent/JP4037404B2/en
2006-05-31 Priority to PCT/JP2006/310897 priority patent/WO2007138695A1/en
2009-01-16 Assigned to FUJIKURA LTD. reassignment FUJIKURA LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ITO, MASANORI, OHASHI, MASAKAZU, URUGA, KEN-ICHI
2009-05-14 Publication of US20090122554A1 publication Critical patent/US20090122554A1/en
2011-01-11 Publication of US7866853B2 publication Critical patent/US7866853B2/en
With respect to light-emitting element modules which mount and package light-emitting elements such as LEDs, a surface-mount type package structure like that shown in FIG. 10 has heretofore been used when attempting to miniaturize the packaging structure. In this light-emitting element module, a concave portion is provided in a substrate 3 composed of resin or ceramic, two positive/negative electrodes 4, 4 are arranged on the bottom face of the concave portion, and a light-emitting element 1 is electrically connected and fixed to one of the electrodes 4 via conductive paste or the like. The top side of the light-emitting element 1 is electrically connected to the other electrode 4 by a wire bonding 2 such as gold wire. These electrodes 4, 4 extend to the exterior of the substrate, After mounting the light-emitting element 1, the concave portion is filled with a sealing resin 5 of high optical transmittance such as epoxy resin, and the sealing resin 5 is cured to seal the light-emitting element 1. Particularly in the case of white LEDs, a blue LED is used as the light-emitting element, and a blue-excited yellow-emitting fluorescent material is mixed into sealing resin which is similarly used to fill the reflective concave portion,
As a conventional structure of this LED unit, one may adopt a structure in which numerous bullet type LEDs are mounted onto an electronic substrate, or a form in which numerous surface-mount type LEDs are mounted. To manufacture this unit it is necessary to adopt a process wherein the bullet type or surface-amount type LEDs are fabricated, and electrically connected by soldering or the like to an electronic substrate on which an electronic circuit pattern that suits their needs has been prepared, Accordingly, it is necessary to have a two-stage production process pertaining to the bullet type or surface-mount type LEDs and the LED units in which they are assembled.
In light of these demands, as shown in FIG. 11, a structure has come to predominate in which a substrate is provided with a heat dissipation metal board 8 such as aluminum board or copper board and an insulating layer 7 provided on the board 8. The LED unit shown in FIG. 11 adopts a structure wherein the insulating layer 7 is provided on the heat dissipation metal board 8, multiple electrodes 4 are provided on the insulating layer 7, light-emitting elements 1 are provided on these electrodes 4, the top side of t respective light-emitting element 1 is electrically connected to the adjacent electrode by a wire bonding 2, a reflective board 6 which has multiple holes having sloped parts 6 a is placed so that the respective light-emitting element 1 is positioned at the center of the hole, and the light-emitting elements 1 are scaled by filling the respective holes with sealing resin 5 and then curing the sealing resin 5. FIG. 12 is a plan view of the state where the light-emitting elements 1 are mounted on the substrate, This structure is disclosed, for example, in Patent Document 2.
1, A light-emitting element is mounted on an electrode in a reflective cup of a substrate by using silver paste or, when the electrode material of the light-emitting element is AuSn or the like, by a so-called eutectic soldering—a connection in which heat and vibration are imparted—resulting in electrical continuity, Furthermore, the light-emitting element is connected to a counter electrode by a wire bonding. With respect to light-emitting elements having electrodes on only one side, two positive/negative electrodes are both subjected to wire bonding. Furthermore, with respect to light-emitting elements having electrodes on only one side, it is also possible to connect by flip-chip packaging via bumps composed of gold or the like arranged on top of the electrodes.
On the other hand, when undertaking to directly mount light-emitting elements onto the substrate without providing reflective cups, as shown in FIG. 15, one may also conceive of a method where electrodes 12 are disposed on a flat substrate 11, light emitting elements 9 and wire bondings 10 are mounted onto the electrodes 12 by the same method described above, and sealing resin 13 is molded by a molding method such as transfer molding such that the light-emitting elements 9 and wire bondings 10 are subjected to resin sealing. However, with this method, it is difficult to dispose the sealing resin 13 in accurate positions due to problems such as the dimensional tolerance of the substrate. Furthermore, in the case of white LEDs, as fluorescent material is intermixed with the sealing resin 13, when the form of the sealing resin 13 is unstable, variations arise in he distance pertaining to the passage of the light emitted from the light-emitting elements 9 through the interior of the sealing resin 13 containing fluorescent material, thereby becoming difficult to control the color as required.
Conventional multilayered aluminum substrates and aluminum nitride substrates have sufficient heat dissipation properties, but in order to fabricate the reflective cup shape, it is necessary to further stack a reflective-cup-forming base material on the substrate in the aforementioned manner. When particular emphasis is placed on heat dissipation properties, it goes without saying that it is appropriate to use metal as the material for configuring the substrate from the standpoint of thermal conductivity, but when metal is used in the substrate, it also has properties of electrical conductivity, resulting in the necessity of performing insulating treatment between the electrode and the base material, This insulating sheet also constitutes an element in the laminar structure, further complicating the structure.
The present invention was made in view of the above circumstances, and has an object of providing a light-emitting element mounting substrate which has excellent optical extraction efficiency from a light-emitting element and which can be produced at low cost, and its manufacturing method, a light-emitting element module which mounts and packages a light-emitting clement on the substrate and its manufacturing method, and a display device, lighting device and traffic light which use this light-emitting element module.
In order to achieve the aforementioned objectives, the present invention provides a light-emitting element mounting substrate which includes: a core metal provided with a reflective cup which reflects light emitted from a mounted light-emitting element in a prescribed direction; and an enamel layer having a thickness within a range of 50 μm to 200 μm, and provided on a surface of the core metal,
In the method of manufacturing a light-emitting element module of the present invention, it is preferable to seal the light-emitting element by resin which is intermixed with fluorescent material
FIG. 3 is a plan view which shows the first embodiment of the enameled substrate of the present invention,
20,30,40 light-emitting element module
21,31,41 enameled substrate (light-emitting element mounting substrate)
22,32,42 core metal
23,33,43 enamel layer
24,34,44 light-emitting element
25,35,45 wire bonding
26,36,46 sealing resin
27,37,47 electrode
28,38,48,51,56,60 reflective cup
29 a, 39 a, 49 a, 52,57 bottom part
29 b, 39 b, 49 b, 53,58 sloped part
50,54,59 groove
The material of the enamel layer 23 disposed on the surface of this core metal 22 can be selected for use from among materials primarily composed of glass which are conventionally used to form enamel layers on metal surfaces, In the present invention, the thickness range of the enamel layer 23 disposed on the surface of the core metal 22 is 50 μm to 200 μm. When the thickness of the enamel layer 23 is less than 50 μm, there is a possibility of occurrence of cracking in the enamel layer at the time of baking onto the surface of the core metal 22, and so exposure of the internal metal core to the outside, resulting in occurring a decline in insulating performance as well as a decline in the long-term reliability of the substrate due to oxidation and the like of the core metal 22. When the thickness of the enamel layer 23 exceeds 200 μm, the possibility of cracking in the enamel layer likewise arises, and Evermore there is the problem that the enamel layer tends to collect at the circumferential edge of the bottom part 29 a during baking, with the result that the light-emitting element 24 is not able to be mounted on the bottom part 29 a due to a reduction in mounting space. In the present invention, by forming an enamel layer 23 with a thickness range of 50 μm to 200 μm on the surface of the core metal 22, it is possible to form a uniform enamel layer 23 which obtains excellent insulating performance and which is free of cracks. Moreover, with an enamel layer 23 of this thickness, the shape of the underlying core metal 22 can be reproduced as is, and the shapes of the reflective cups 28 formed in the core metal 22 can also be reproduced as is in the enamel layer 23.
There are no particular limitations on the light-emitting elements 24, and semiconductor light-emitting elements such as LEDs and laser diodes (LDs) may be suitably used. There are also no particular limitations on the emission color of the light-emitting elements 24 used in the present invention—blue, green, red or other emission colors are acceptable. Furthermore, one may use white LEDs which combine semiconductor elements of blue emission color composed of nitride compound semiconductors and fluorescent material (e.g., yttrium-aluminum-garnet fluorescent material activated by cerium) which absorbs the light of the blue color at least in part and which conducts wavelength conversion to light of the visible spectrum. With respect to the multiple light-emitting elements 24 mounted in rows on the enameled substrate 21, LEDs or the like of the same emission color may be used—for example, in applications pertaining to traffic lights, etc.—or LEDs or the like of different emission colors may be sequentially or randomly arranged and used as display devices. Furthermore, display devices using LEDs may be configured by sequentially or randomly arranging numerous blue LEDs, green LEDs and red LEDs on top of the enameled substrate 21 of large area Moreover, one may configure planar lighting devices of large area by using white LEDs as the light-emitting elements 24 and mounting the numerous white LEDs in vertical and horizontal rows on a large enameled substrate 21.
When fabricating the enameled substrate 41 which has the reflective cups 48, enamel material is applied to the core metal 42, and the enamel layer 43 is fixed to the surface of the core metal 42 by baking. When baking, there is a possibility that the glass material may temporarily melt and run prior to baking, resulting in rounding of the circumferential edge of the bottom part of the cup. Depending on the circumstances, this may make it impossible to secure a smooth plane for mounting the light-emitting element 44, In the present embodiment, an enameled substrate 41 having a groove 50 disposed around the circumferential edge of the bottom part 49 a is used, with the result that glass material collects in the groove of the circumferential edge of the bottom part, and the remainder of the bottom pat 49 a can be maintained in a flat state. The portion of the bottom part 49 a apart from where the groove 50 is disposed is the portion for mounting the light-emitting element 44. By giving it an appropriate area, it is possible to preserve a flat portion for mounting the light-emitting element.
FIG. 6 is a figure which shows one example of a grooved reflective cup, In this illustration, a reflective cup 51 adopts a configuration in which a groove 54 is formed between a bottom part 52 and a sloped part 53, and a protrusion 55 is disposed at the circumferential edge of the bottom part 52. With this suture, in addition to providing the groove 54, the protrusion 55 is disposed at the circumferential edge of the bottom part 52, thereby making it possible to prevent melted glass from running into the groove 54.
Based on the results of Table 2, in reference example 2, the light-emitting elements were unable to be mounted in 2 out of 9 places. As to the reason, upon observation of the sectional profile, it would seem that the form of the substrate at the circumferential edge of the bottom face 62 of the concave portion had adopted a rounded form as shown in FIG. 9, thereby reducing the flat region which enables mounting of the light-emitting element. As to the cause of adoption of this for, it would seem that when the enamel layer underwent baking, the glass powder of the raw material melted, ran, and collected, With an enamel layer of a thickness of 200 μm or less, a sufficient region is secured for mounting of a light-emitting element.
a core metal provided with a reflective cup which reflects light emitted from a mounted light-emitting element in a prescribed direction; and
an enamel layer having a thickness within a range of 50 μm to 200 μm, and provided on a surface of the core metal.
forming a reflective cup which reflects light emitted from a mounted light-emitting element in a prescribed direction, at a predetermined position on a core metal; and
subsequently applying and baking enamel material on a surface of the core metal, to form an enamel layer which has a thickness within a range of 50 μm to 200 μm on the surface of the core metal.
forming a light-emitting element mounting substrate by forming a reflective cup which reflects light emitted from a mounted light-emitting element in a prescribed direction, at a predetermined position on a core metal, and subsequently applying and baking enamel material on a surface of the core metal, to form an enamel layer which has a thickness within a range of 50 μm to 200 μm on the surface of the core metal;
US12/325,113 2004-11-19 2008-11-28 Light-emitting element mounting substrate and manufacturing method thereof, light-emitting element module and manufacturing method thereof, display device, lighting device, and traffic light Active 2026-08-09 US7866853B2 (en)
US7866853B2 US7866853B2 (en) 2011-01-11
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