JP2012099555A - Light-emitting device for backlight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device for a backlight having a good heat dissipation property and an excellent long-term durability, which can be manufactured at a low cost.SOLUTION: The light-emitting device for a backlight comprises: a deformed cross section plate of copper or copper alloy having convex and concave portions, and a thermal conductivity of 150 W/(mK) or larger with its surface covered with one selected from a group consisting of Sn plating, Ni plating, Ag plating, and Ag-Sn alloy plating, which have degrees of brilliance of 80-110%; a plurality of light-emitting elements directly mounted on the bottom face of the concave portion of the deformed cross section plate; cathode and anode patterning circuits formed on the bottom face of the concave portion; a wiring line for connecting between the light-emitting elements in series, a wiring line for connecting the first element of the series-connected light-emitting elements to the anode patterning circuit, and a wiring line for connecting the last light-emitting element to the cathode patterning circuit; and a transparent resin for sealing the concave portion to cover the plurality of light-emitting elements.

Description

  The present invention relates to a backlight light-emitting device, and more particularly to a COB-type backlight light-emitting device excellent in durability and heat dissipation.

  As a COB type backlight device, one that directly mounts a plurality of LED elements on a resin substrate is known. In this type of backlight device, a glass epoxy resin (thermal conductivity: 0.2 to 0.3 W / mK) is used as a substrate, and an electrode pattern made of a conductive metal is formed on the substrate. In a display device using a backlight device, since a display portion is provided to face the mounting surface of the LED element of the substrate, it is necessary to reflect light incident from the LED element to the substrate side on the substrate. Therefore, the substrate surface is generally covered with a white resin solder resist layer to increase the reflectance of the substrate surface. However, the COB type backlight device using a resin substrate has a low thermal conductivity of the substrate, and the heat generated in the LED element is likely to be trapped in the device. There was a risk of yellowing.

In addition, an LED display device in which a transparent conductive film made of ITO is formed on a transparent glass substrate has been proposed. With this LED display device, the LED chip mounting portion and the metallized portion on the substrate side can be kept transparent. However, since such a LED display device has a transparent substrate, the light emitted from the LED element is transmitted through the substrate and is opposed to the mounting surface of the substrate. It is impossible to irradiate light accurately to the part, and the performance as a backlight device tends to be lowered.

  As these measures, there is the following patent document as a backlight device capable of improving the thermal conductivity of a substrate and suppressing deterioration during long-term use and a display device equipped with the backlight device.

  In Patent Document 1, the substrate on which each LED element is mounted is made of glass, and heat generated in each LED element is efficiently dissipated from the substrate, and each LED element is made reflective by making the glass reflective. The heat conductivity of the substrate is improved by preventing the light emitted from the substrate from being transmitted through the substrate, and irradiating the display portion facing the LED element mounting surface of the substrate accurately. Disclosed is a backlight device capable of suppressing deterioration during use and a display device including the backlight device.

  In Patent Document 2, in an LED package in which a plurality of LED chips are mounted in a recess having a side surface and a bottom surface formed of a resin and / or a conductive metal, and the recess is sealed with a translucent resin, A low-cost LED package that reduces output loss in a 3-in-1 package or a multi-chip package, in which a barrier separating each LED chip is integrally formed of the same resin or the same conductive metal as the bottom surface It is disclosed.

  Patent Document 3 discloses an LED light-emitting device in which the surface of the silver plating in the LED chip housing recess is not easily oxidized or sulfided and has good heat dissipation. A printed circuit board with an opening having a predetermined conductive pattern formed on the upper surface and an area for die-bonding the LED chip is affixed on a base anodized on an aluminum plate, and a base located at the opening of the printed board. The LED chip is die-bonded with a transparent paste on the base, the upper electrode of the LED chip and the conductive pattern formed on the printed circuit board are wire-bonded with a gold wire, and the outer peripheral surface of the printed circuit board covers the LED chip Attach a case with a lens made of silicone resin having a sealing resin injection hole to the part, and inject a sealing resin made of rubber / gel silicone resin from the sealing resin injection hole provided in the case with lens to attach the LED chip. Manufactured by sealing.

  In Patent Document 4, as a structure and manufacturing method for improving the heat dissipation and manufacturing cost of a semiconductor package, a semiconductor is die-bonded to a part of a metal substrate, a semiconductor electrode is bonded to another part, and both parts are divided. However, there is disclosed a structure in which the metal substrates are connected to each other by a sealing resin and both portions of the metal substrate are also electrode terminals. A large number of semiconductors are die-bonded at predetermined positions on the collective metal substrate, each electrode of the semiconductor and another predetermined position on the metal plate are wire-bonded, and a resin for sealing the semiconductor is filled over the entire surface of the substrate, and After being cured, each predetermined region and each other predetermined region of the collective metal substrate are manufactured by performing a process of dividing the collective metal substrate and the seal resin for each device by separating and separating the collective metal substrate and the seal resin for each device. .

JP 2009-170847 A JP 2008-41699 A Japanese Patent Laid-Open No. 2007-129053 Japanese Unexamined Patent Publication No. 2000-77725

The backlight device disclosed in the above-mentioned patent document cannot be said to have sufficient heat dissipation and durability, and the manufacturing cost is not low.
The present invention provides a light-emitting device for a backlight that is excellent in heat dissipation and excellent in durability during long-term use and at a low manufacturing cost.

As a result of intensive studies, the present inventors have found that the following matters are important in order to provide an inexpensive backlight light-emitting device with excellent heat dissipation and durability during long-term use and at a low manufacturing cost. It was.
(1) To improve the thermal conductivity, a copper or copper alloy plate having a thermal conductivity of 150 W / (m · K) or more is used as a substrate on which the LED chip is directly mounted.
(2) To improve the durability, particularly the durability of the reflective layer sealed with resin, the surface of the copper or copper alloy plate as the reflective layer has high durability and heat resistance, and a glossiness of 80 to 110%. A kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag—Sn alloy plating is applied.
(3) In order to simplify the structure and reduce the manufacturing cost and accurately irradiate the display part with light, the reflective part is not formed later on the substrate with a resin or the like, but an unevenness is formed on one side of the copper or copper alloy plate. The reflective portion is integrally formed as a deformed cross-sectional shape, and the surface thereof is subjected to a kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag—Sn alloy plating with a glossiness of 80 to 110%. It is necessary to directly mount a plurality of light emitting elements on the bottom surface of the concave portion, use the side surface of the concave portion as a reflecting portion, and seal the inside of the concave portion with a transparent resin. Furthermore, the flat plate portion on the back side of the copper or copper alloy deformed cross-section plate is directly bonded or screwed to the backlight device fixing portion in the electronic device portion and used as a light emitting device for the backlight, so that handling becomes very easy. .

  That is, the light emitting device for backlight according to the present invention is provided with a kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag—Sn alloy plating having a glossiness of 80 to 110% on the surface. A copper or copper alloy irregular cross-section plate having a convex / concave portion having a thermal conductivity of 150 W / (m · K) or more, a plurality of light-emitting elements mounted directly on the bottom surface of the concave portion of the irregular cross-section plate, and the concave portion The cathode patterning circuit and the anode patterning circuit formed on the bottom surface of the substrate, the wiring for connecting the plurality of light emitting elements in series, and the head element of the plurality of light emitting elements connected in series are connected to the anode patterning circuit. A wiring for connecting the wiring and the terminal element to the cathode patterning circuit, and a transparent resin for sealing the inside of the recess so as to cover the plurality of light emitting elements. Characterized in that made the.

In the present invention, the plating applied to the surface of the copper or copper alloy cross-section strip is from the group consisting of Sn plating, Ni plating, Ag plating, and Ag-Sn alloy plating from the viewpoint of heat resistance and sulfidation resistance to the resin. It is a kind of selected plating, and its glossiness is 80 to 110% from the viewpoint of reflectance. When the glossiness is less than 80%, the reflection effect is insufficient, and when it exceeds 110%, the reflection effect is saturated and wasted. The thickness of the plating is preferably 0.2 to 3.0 μm. If the thickness is less than 0.2 μm, the heat resistance and sulfidation resistance are insufficient, and if it exceeds 3.0 μm, the effect is saturated and expensive Ag is used, which is expensive. It becomes useless.
Further, if the thermal conductivity of the copper or copper alloy cross section is less than 150 W / (m · K), the effect is not sufficient. However, increasing to 350 W / (m · K) is useless from the viewpoint of manufacturing cost, and is practically preferably 160 to 300 W / (m · K).

  Furthermore, in the light emitting device for backlight of the present invention, the copper alloy deformed cross-sectional plate is Fe; 1.5 to 2.6 mass%, P; 0.008 to 0.15 mass%, and Zn; 0.01 to 0 0.5% by mass, the balance being composed of Cu and inevitable impurities, the composition having an arithmetic average roughness Ra of 0.02-0.05 μm, and a maximum height Rz of 0.20-0. The ratio Rq / Rz of the root mean square roughness Rq to the maximum height Rz is 0.10 to 0.25.

The copper alloy irregular cross-section plate having this composition and surface roughness has an excellent balance of heat resistance, durability and heat dissipation, and by using this, the mechanical strength at high temperature is increased and the backlight device has Heat dissipation is improved.
Moreover, in order to improve the intensity | strength of a copper alloy irregular cross-section board, in addition to this composition, Ni; 0.003-0.5 mass% and / or Sn; You may contain 0.003-0.5 mass%. .
The arithmetic average roughness Ra of the surface is 0.02 to 0.05 μm, the maximum height Rz is 0.20 to 0.40 μm, and the ratio Rq / of the root mean square roughness Rq to the maximum height Rz When Rz is 0.10 to 0.25, the contact thermal resistance with the LED mounted directly on the surface is reduced, and the heat dissipation is further increased. If Ra is less than 0.02 μm, Rz is less than 0.20 μm, or Rq / Rz is less than 0.10, the effect is saturated, and a special surface treatment is required for manufacturing, which increases costs and is useless. When Ra exceeds 0.05 μm, Rz exceeds 0.40 μm, or Rq / Rz exceeds 0.25, the effect is insufficient.

  Furthermore, the electronic or electrical equipment using the liquid crystal of the present invention is characterized in that the backlight light emitting device of the present invention is directly fixed to the backlight light emitting device fixing portion in the device by bonding or screwing.

  In the light emitting device for backlight according to the present invention, the back side of the copper or copper alloy deformed cross section plate is a flat plate portion, and this flat plate portion is directly bonded to the backlight device fixing portion in the electronic or electric equipment portion using liquid crystal. Alternatively, by screwing, it can be easily mounted without a complicated mounting mechanism.

  According to the present invention, it is possible to provide a light-emitting device for a backlight having good heat dissipation and excellent durability during long-term use and at a low manufacturing cost.

It is a perspective view of the light emitting device for backlight of the present invention.

An embodiment of a light emitting device for backlight according to the present invention will be described with reference to FIG.
The light emitting device for backlight 1 of the present invention has a surface on which a kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag—Sn alloy plating with a glossiness of 80 to 110% is applied. A copper or copper alloy modified cross-section plate 2 having a convex and concave portion having a thermal conductivity of 150 W / (m · K) or more, and a plurality of components mounted directly (COB) on the bottom surface of the concave portion 3 of the copper or copper alloy modified cross-sectional plate 2 A plurality of light emitting elements 4, 4 a, 4 b, a cathode patterning circuit 5 b and an anode patterning circuit 5 a formed on the inner bottom surface of the recess 3, a wiring 6 for connecting a plurality of light emitting elements 4, 4 a, 4 b in series, A wiring 7a for connecting the leading element 4a of the plurality of light emitting elements connected in series to the anode patterning circuit 5a and a wiring for connecting the terminal element 4b to the cathode patterning 5b circuit. 7b and a plurality of light emitting elements 4, 4a, comprised of a transparent resin 8 which seals the inside recess 3 so as to cover the 4b. The cathode patterning circuit 5b and the anode patterning circuit 5a are connected to a power source (not shown).

  From the viewpoint of heat dissipation, the copper or copper alloy that is the material of the copper or copper alloy modified cross-section plate 2 preferably has a thermal conductivity of 160 to 300 W / (m · K), heat resistance, durability, From the viewpoint of balance of heat dissipation, it contains Fe; 1.5 to 2.6% by mass, P; 0.008 to 0.15% by mass, and Zn; 0.01 to 0.5% by mass, with the balance being It has a composition composed of Cu and inevitable impurities, has an arithmetic average roughness Ra of 0.02 to 0.05 μm, a maximum height Rz of 0.20 to 0.40 μm, and a root mean square roughness Rq. The ratio Rq / Rz of the maximum height Rz is preferably 0.10 to 0.25. Moreover, in order to improve intensity | strength, in addition to this composition, you may contain Ni; 0.003-0.5 mass% and / or Sn; 0.003-0.5 mass%.

  The arithmetic average roughness Ra of the surface is 0.02 to 0.05 μm, the maximum height Rz is 0.20 to 0.40 μm, and the ratio Rq / Rz of the root mean square roughness Rq to the maximum height Rz is When it is 0.10 to 0.25, the contact thermal resistance with the LED directly mounted on the surface is reduced, and the heat dissipation is further increased. If Ra is less than 0.02 μm, Rz is less than 0.20 μm, or Rq / Rz is less than 0.10, the effect is saturated, and a special surface treatment is required for manufacturing, which increases the manufacturing cost and is useless. . When Ra exceeds 0.05 μm, Rz exceeds 0.40 μm, or Rq / Rz exceeds 0.25, the effect is insufficient.

A kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag-Sn alloy plating applied to the surface of the copper or copper alloy deformed cross-section plate 2 is heat resistant and sulfide resistant to resin. From the viewpoint, the thickness is 0.2 to 3.0 μm, and from the viewpoint of reflectance, the glossiness is 80 to 110%. When the glossiness is less than 80%, the reflection effect is insufficient, and when it exceeds 110%, the reflection effect is saturated and wasted. When the plating thickness is less than 0.2 μm, the heat resistance and sulfidation resistance are insufficient, and when it exceeds 3.0 μm, the effect is saturated and the cost is wasted.
Further, the plating is particularly preferably an Ag—Sn alloy plating in view of resistance to sulfidation, and considering the cost, durability, and heat resistance, the plating may be a two-layer or three-layer plating having an underlayer. preferable.

Next, the light emitting device 1 for backlight using Ag—Sn alloy plating having a base layer will be described.
Three layers are formed on the surface of the deformed cross-section plate 2 formed by rolling a copper or copper alloy flat plate into which a thick section and a thin section are aligned in the width direction and then annealing and finishing and rolling into a predetermined shape. In the case of plating, Ni plating, Cu plating, and Sn plating are performed in order, and after reflow treatment, the oxide film on the surface is removed by an electrochemical reduction method, and Ag strike plating using a cyanide compound on the surface Ag—Sn alloy plating is applied by the method. When the base layer is a two-layer plating, Ni plating is unnecessary.
In this case, the Sn metal surface of the Sn plating layer is exposed by reducing and completely removing the oxide film of the Sn plating layer in a weak alkaline electrolyte by an electrochemical reduction method, and the next Ag plating is adhered. be able to. Moreover, the mutual diffusion of Ag and Sn can be ensured by performing the alloying treatment after the Ag plating.
The conditions for Ag strike plating are as shown in Table 1.

Here, if the concentration of potassium potassium cyanide is less than 1 g / L, a desired area coverage cannot be obtained for the Sn plating layer, and if it exceeds 8 g / L, the Ag plating surface becomes rough. 1-8 g / L is preferable.
The alloying treatment conditions after Ag strike plating are as shown in Table 2.

By this alloying treatment, Ag on the surface and Sn under the surface are diffused and alloyed to form an Ag ₃ Sn alloy layer on the surface.
Moreover, in order to increase the durability against sulfidation of the resin used for sealing, it is preferable to form a transparent tin oxide film of 5 to 20 nm on the surface of the Ag ₃ Sn alloy layer.
By the above plating method, the copper or copper alloy modified cross-sectional plate 2 having the Ni plating layer, the Cu—Sn alloy layer, and the Ag—Sn alloy plating layer is completed, and the outermost Ag—Sn alloy plating layer is The glossiness is 80 to 110%. Thereby, the internal side surface 11 of the recessed part 3 of the copper or copper alloy modified cross-section board 2 acts as a good reflector having durability and heat resistance, and forms an excellent backlight device.
Further, such plating may not be applied to the back surface 9, the side surface 10, and the convex surface 12 of the copper or copper alloy modified cross-section plate 2.

A plurality of light emitting elements 4, 4 a, 4 b are directly mounted on the bottom surface of the concave portion 3 of the copper alloy modified cross-section plate 2 on which the Ag—Sn alloy plating is applied. In this case, Au—Sn solder is vapor-deposited on the surface of the light emitting elements 4, 4 a, 4 b in contact with the bottom surface of the recess 3, and heated at a temperature of 240 to 310 ° C. while being pressed, whereby the Ag—Sn alloy plating layer A ternary Au—Ag—Sn alloy layer is formed between them, and the light emitting element 4 is firmly mounted.
In order to obtain an Au—Ag—Sn alloy layer having no defects such as voids and high bonding strength, it is preferable to set the heating temperature to 240 ° C. or higher. Even if the heating temperature exceeds 310 ° C., no further improvement in bonding strength cannot be expected, and thermal stress increases, which is not preferable.

The anode patterning circuit 5a and the cathode patterning circuit 5b are bonded to the bottom surface of the concave portion 3 of the copper or copper alloy deformed cross-section plate 2 with Ag—Sn alloy plating applied to the surface with an insulating adhesive tape or an adhesive resin. Also. From the viewpoint of durability and heat resistance, the anode patterning circuit 5a and the cathode patterning circuit 5b are preferably formed on a copper strip having Ag or Ag—Sn alloy plating applied to the surface thereof.
A plurality of light emitting elements 4, 4 a, 4 b are connected in series by wiring (gold wire) 6, and the light emitting elements 4 a, 4 b at the end are connected to the patterning circuits 5 a, 5 b by wiring 7 a, 7 b (gold wire). Is done. The patterning circuits 5a and 5b are connected to a power source by wiring (not shown).

  Further, the inside of the recess 3 is sealed with a transparent resin 8 so as to cover the plurality of light emitting elements 4, 4a, 4b. The material of the transparent resin 8 is not particularly limited, but a silicone resin is preferable in consideration of transparency, durability, heat resistance, and the like.

  Such a backlight light emitting device 1 of the present invention is such that the flat portion of the back surface 9 is directly joined to the backlight device fixing portion (not shown) in the electronic device portion by an adhesive or screw fixing holes formed at both ends. 13 is used by directly joining via 13.

  Trade name of Mitsubishi Shindoh Co., Ltd., MAX251C (Cu; 95% by mass or more, Ni; 1.3 to 2.7% by mass, Si; 0.2 to 0.8% by mass, Sn; 0.2 to 0 0.8% by mass, Zn: 0.5-1.5% by mass, the balance being inevitable impurities), TAMAC194 (Cu: 97% by mass or more, Fe: 2.1-2.6% by mass, P: 0.015 Using a copper alloy flat plate of 0.15% by mass, Zn: 0.05-0.20% by mass, the balance being inevitable impurities), a deformed cross-sectional plate in which a thick part and a thin part are aligned in the width direction by rolling 1 is manufactured and annealed, and then finish-rolled. The dimensions shown in FIG. 1 are as follows: length L: 100 mm, overall width W: 20 mm, recess bottom width W1: 15 mm, overall height H: 10 mm, to recess bottom Height H1: 5 mm, angle θ between the bottom surface of the recess and the inner side surface; surface roughness shown in Tables 3 and 4 at 75 ° Each of the irregular cross-sectional plates was prepared. Table 3 shows the results using MAX251, and Table 4 shows the results using TAMAC194.

Next, after cleaning the surface of the irregular cross-section plate, Cu plating and Sn plating are performed in this order, and the reflow treatment is performed by heating to form a Cu-Sn alloy layer and a two-layer plating in which an Sn plating layer is formed thereon An odd-shaped cross-section plate was prepared, and the Sn plating surface was removed from the Sn plating layer in the electrolytic solution by an electrochemical reduction method, and the film thickness was changed under the conditions shown in Table 1. Ag-Sn alloy having a plating thickness and glossiness shown in Tables 3 and 4 after being subjected to Ag strike plating and subjected to alloying and discoloration prevention treatment in an aqueous solution containing a benzothiazole compound under the conditions shown in Table 2. Each modified cross-section board having a layer on the surface was produced.
Next, an LED chip made by CREE (length 0.9 mm × width 0.9 mm × height 200 μm for bonding to the bottom surface) is formed on the bottom surface of the concave portion of the deformed cross-section plate subjected to the Ag—Sn alloy plating. Three pieces (Au—Sn solder deposited) were arranged in series at intervals of 6 mm, heated at a temperature of 240 to 310 ° C. while being pressed, and directly joined to the bottom surface of the recess.

Next, the cathode and anode patterning circuit (copper strip whose surface is plated) is applied to the insulating adhesive tape on the bottom surface where the LED chip in the concave portion of the deformed cross-section plate plated with Ag-Sn alloy is not bonded. The electrodes of the LED chips on both ends arranged in series and the cathode and anode patterning circuits were bonded with gold wires. Each LED chip was also bonded with a gold wire.
Next, it is sealed and cured with a silicone resin manufactured by Shin-Etsu Chemical Co., Ltd. so as to completely cover the inside of the recess where the LED chip is directly mounted, and Examples 1 to 6 and Examples 11 to 16, The backlight light emitting devices shown in Comparative Examples 1 to 4 and Comparative Examples 11 to 14 were produced.

The cathode patterning circuit and the anode patterning circuit of the backlight light emitting device thus manufactured were energized to measure heat dissipation and durability. The measurement results are shown in Tables 3 and 4.
For heat dissipation, the light emitting device is attached to an aluminum plate (200 mm long, 65 mm wide, 0.8 mm thick) imitating the backlight housing with adhesive resin, energized for 1000 hours, and then the voltage per element. 3.3V and a current of 350 mA were loaded to emit light, and the element temperature (junction temperature Tj) was measured with an infrared thermography (TH9100 manufactured by NEC Saneisha).
Durability was measured by measuring the luminance after conducting an acceleration test, energizing for 1000 hours in an atmosphere of 85 ° C./85% RH, and calculating the rate of decrease in luminance relative to the initial luminance. The luminance was measured with a luminance meter (CS-100A manufactured by Konica Minolta Sensing).

From the results of Tables 3 and 4, the backlight light-emitting device of the present invention has good heat dissipation and durability during long-term use, in particular, excellent durability of the resin-sealed reflective layer, resulting in lower brightness. I find it difficult.
Further, since the structure of the backlight device of the present invention is simplified, the manufacturing cost is low, and the backlight device can be easily used by directly bonding or screwing to the backlight device fixing portion in the electronic device section.

  As mentioned above, although the manufacturing method of embodiment of this invention was demonstrated, this invention is not limited to this description, A various change can be added in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Light-emitting device for backlights 2 Copper or copper alloy irregular cross-section board 3 Recessed copper or copper alloy irregular cross-section board 4, 4a, 4b Light emitting element 5a Anode patterning circuit 5b Cathode patterning circuit 6, 7a, 7b Wiring 8 Transparent resin

Claims (3)

  A thermal conductivity of 150 W / (m · K) on the surface of which a kind of plating selected from the group consisting of Sn plating, Ni plating, Ag plating, and Ag—Sn alloy plating with a glossiness of 80 to 110% is applied. The copper or copper alloy irregular cross-sectional plate having the convex and concave portions as described above, a plurality of light emitting elements mounted directly on the bottom surface of the concave portion of the irregular cross-sectional plate, the cathode patterning circuit and the anode patterning formed on the bottom surface of the concave portion A circuit, a wiring for connecting the plurality of light emitting elements in series, a wiring for connecting the head element of the plurality of light emitting elements connected in series to the anode patterning circuit, and a terminal element for connecting to the cathode patterning circuit For a backlight comprising a wiring and a transparent resin for sealing the inside of the recess so as to cover the plurality of light emitting elements Light equipment.   The copper alloy deformed cross-section plate contains Fe; 1.5 to 2.6% by mass, P; 0.008 to 0.15% by mass and Zn; 0.01 to 0.5% by mass, with the balance being Cu and It has a composition consisting of inevitable impurities, has a surface arithmetic average roughness Ra of 0.02 to 0.05 μm, a maximum height Rz of 0.20 to 0.40 μm, and a root mean square roughness Rq and a maximum The light emitting device for backlight according to claim 1, wherein the ratio Rq / Rz of the height Rz is 0.10 to 0.25.   An electronic device using liquid crystal, characterized in that the backlight light emitting device according to any one of claims 1 to 2 is directly fixed to a backlight light emitting device fixing portion in a device by bonding or screwing. Or electrical equipment.

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