TW201424056A - Light-emitting device - Google Patents

Abstract

This invention provides a light-emitting device that is able to reduce the amount of light taken into a coating film and improve the efficiency to take out light output from a LED chip even if a coating film is provided to prevent oxidation or vulcanization of a metal film. To this end, the light-emitting device comprises a substrate 1, a metal film 2 formed on the surface of the substrate 1, a LED chip 4 provided on the metal film 2 and a coating film 3 formed on the metal film. The coating film 3 has a through hole 31 which penetrates in the direction of the film thickness and in which the LED chip 4 is placed. The through hole 31 is larger than the LED chip 4 in a plane view, and a gap between the outer periphery of the LED chip 4 and the inner periphery of the through hole 3 is formed.

Description

Illuminating device

The present invention relates to a light-emitting device comprising: a substrate; a metal film formed on a surface of the substrate; and an LED chip disposed on the metal film.

Conventionally, there has been known a light-emitting device in which a metal film that reflects light is formed on a substrate and an LED chip is placed on the metal film, so that light emitted from the LED chip, for example, light emitted toward the substrate side is returned. The desired light illuminates the side.

However, in such a light-emitting device, when the metal film is in contact with the outside air, it gradually oxidizes or vulcanizes and turns black. Therefore, the reflectance of the metal film is lowered, and it is difficult for the light emitted from the LED chip to be reflected toward the light-irradiated side. The extraction efficiency of light is reduced.

Therefore, in order to solve such a problem, a light-emitting device 100A shown in Fig. 6(a) in which a glass film having gas barrier properties is provided in order to prevent contact between the outside air and the metal film 2A has been proposed. 3A covers the metal film 2A, and the LED wafer 4A is placed on the glass film 3A (see Patent Document 1). Further, the component symbol 6A is a light-transmitting resin layer, and generally has a refractive index lower than that of the glass film 3A.

However, in the manner of the light-emitting device 100A, the LED chip 4A is placed on the glass film 3A, and the light emitted from the LED chip 4A toward the metal film 2A side is incident on the glass film 3A, and is incident. Most of the light rays are repeatedly reflected in the glass film 3A due to the relationship between the refractive index of the glass film 3A and the light-transmitting resin layer 6A, and cannot be extracted to the light-emitting side. That is, although the light-emitting device 100A can prevent the change of the metal film 2A over time, since there is light introduced into the glass film 3A, there is a problem that the extraction efficiency of light is lowered. In addition, since the LED wafer 4A is placed on the glass film 3A having less thermal conductivity than the metal, the heat generated by the LED wafer 4A does not dissipate heat to the substrate 1A side, and it is difficult to obtain desired performance.

Further, a light-emitting device 100B shown in FIG. 6(b) is proposed, in which the LED chip 4B is placed on the metal film 2B, and the metal film 2B and the LED are covered by the glass film 3B. Both of the wafers 4B prevent changes in the metal film 2B over time (refer to Patent Document 2). Further, the component code 6B is a light-transmitting resin layer similar to the above, and has a refractive index lower than that of the glass film 3B.

However, in the manner of the light-emitting device 100B, the metal film 2B and the LED wafer 4B are covered with the glass film 3B. Since the thermal expansion rates of the metal film 2B and the glass film 3B are different, the amount of thermal deformation is different, so that the LED chip 4B is applied. Heating stress. Also, since such thermal stress is applied, the LED wafer 4B is cracked and its light-emitting characteristics are changed.

[First technical literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-34487

Patent Document 2: JP-A-2009-33107

The present invention is to solve the above problems in one place, and an object of the invention is to provide a light-emitting device which can prevent oxidation and vulcanization of a metal film by plating, and can reduce the amount of light emitted from the LED wafer into the coating film to enhance light. The extraction efficiency and the prevention of heat dissipation of the LED wafer due to the plating film and the deterioration of the characteristics of the LED wafer due to thermal deformation of the respective constituent members can be prevented.

That is, the light-emitting device of the present invention includes: a substrate; a metal film formed on a surface of the substrate; an LED chip disposed on the metal film; and a plating film formed on the metal film; and the plating film is formed The through hole penetrates the film thickness direction and is internally disposed with the LED chip; in a plan view, the through hole is formed larger than the LED chip, and between the outer peripheral surface of the LED chip and the inner peripheral surface of the through hole A gap is formed.

In addition, as for the above-mentioned metal film, for example, there is a person who can reflect light, and the coating film may be, for example, light transmissive or gas barrier. In this case, since a gap is formed between the outer peripheral surface of the LED chip and the inner peripheral surface of the through hole, there is no plating film in the vicinity of the periphery of the LED wafer, and therefore most of the light emitted from the LED chip toward the metal film side is not incident. To the coating, and reflect on the metal film. Therefore, the proportion of light incident on the plating film can be reduced, and the light is not enclosed in the plating film.

Therefore, the coating can be coated with a metal film to prevent the change of the metal film over time, and the amount of light introduced into the coating film can be reduced, and the light extraction efficiency can be improved.

Further, since the LED chip is not directly disposed on the metal film, heat generated in the LED wafer is efficiently dissipated to the substrate side via the metal film. Therefore, it is possible to prevent the performance of the LED chip from being lowered due to the temperature rise of the LED chip.

Moreover, since the LED wafer is not in contact with the plating film by the gap between the LED wafer and the through hole, the LED wafer is only affected by the thermal deformation of the metal film. Therefore, since many members having different amounts of thermal deformation are in contact with the LED wafer, excessive thermal stress is not applied to the LED wafer, and cracking and luminescence characteristics of the LED wafer can be prevented from being changed.

In order to make the gas barrier property high and to prevent oxidation and vulcanization of the metal film by the plating film as described above, the coating film may be a glass film.

In order to protect the LED chip, a light transmissive resin layer coated on the plating film and the LED wafer may be further provided.

When the light-transmitting resin layer is provided, it is difficult to introduce the light emitted from the LED wafer into the plating film, and the light extraction efficiency is not lowered. For example, the refractive index of the plating film is made to be smaller than that of the light-transmitting resin layer. The rate is even greater.

Further, the size of the gap may be determined by reducing the amount of light incident on the plating film and preventing oxidation and vulcanization of the metal film, and the size of the balance between the two may not be limited thereto, but may be, for example, 5 μm. Above 500 μm. When the gap is less than 5 μm, the proportion of light incident on the plating film cannot be sufficiently reduced. On the other hand, when the gap exceeds 500 μm, the oxidation and vulcanization of the metal film are prevented from becoming insufficient. Among them, in some cases, the gap is 5 μm or more, and the LED chip is also dry and difficult to mount with the plating film, so the gap is preferably 50 μm or more.

According to the light-emitting device of the present invention, since a gap is formed between the outer peripheral surface of the LED wafer disposed in the through hole of the plating film and the inner peripheral surface of the through hole, it is difficult to introduce light emitted from the LED wafer into the plating film. It can prevent the light extraction efficiency caused by the coating from being lowered. Further, since the LED wafer is directly placed on the metal film, heat dissipation of the LED chip can be efficiently performed, and performance degradation due to an increase in temperature of the LED wafer is less likely to occur. Further, the LED chip is only affected by the thermal deformation of the metal film by the gap, and is less likely to cause thermal stress such as cracking of the LED wafer due to a difference in the amount of thermal deformation of the member contacting the LED chip. .

Further, since the metal film is coated with the plating film other than the installation place of the LED chip, it is possible to prevent discoloration due to oxidation and vulcanization of the metal film, and it is difficult to reduce the reflectance due to discoloration and to extract light. Reduced efficiency.

1, 1A‧‧‧ substrate

2, 2A, 2B, 2C‧‧‧ metal film

3, 3A, 3B‧‧ ‧ coating

3C‧‧‧glass film

4, 4A, 4B, 4C‧‧‧ LED chips

6, 6A, 6B, 6C‧‧‧Transparent resin layer

11‧‧‧ hole

31‧‧‧through holes

51‧‧‧ cathode

52‧‧‧Anode

100, 100A, 100B, 100C‧‧‧ illuminating devices

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic top plan view of a light-emitting device according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a light-emitting device in the same embodiment.

Fig. 3 is a view showing a simulation result in the conventional light-emitting device shown in Fig. 6(a).

Fig. 4 is a view showing a simulation result in the light-emitting device of the embodiment.

Fig. 5 is a view showing a simulation result when there is no gap between the LED wafer and the glass film.

6(a) to 6(b) are schematic cross-sectional views showing the configuration of a conventional light-emitting device.

[Preferred form of implementing the invention]

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a plan view of a light-emitting device 100 of the present embodiment, and Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1. In addition, the dimension in the thickness direction in FIG. 2 is increased in size in order to facilitate understanding, and is different from the actual ratio.

As shown in FIGS. 1 and 2, the light-emitting device 100 of the present embodiment includes a substrate 1; a metal film 2 formed on the surface of the substrate 1; an LED chip 4 provided on the metal film 2; and a glass film (coating film) 3 is formed to cover substantially the entire region of the metal film 2, and the light transmissive resin layer 6 is coated on the glass film 3 and the LED wafer 4. Further, in the light-emitting device 100 of the present embodiment, the glass film 3 is not provided on the LED wafer 4 and around the LED wafer 4.

The following sections are explained below.

The substrate 1 is formed, for example, of a ceramic material, and as shown in FIG. 1, the panel portion has a substantially square shape. A central portion of the surface of the substrate 1 is formed with a recess, that is, a hole 11, and an anode 52 and a cathode 51 which are connected to the LED chips 4 by wiring are provided at the bottom.

The metal film 2 is formed of a silver (Ag) film which is coated on the surface of the hole 11 and reflects light emitted from the LED chip 4 toward the substrate 1 side to return to the light irradiation side. As shown in FIG. 2, the metal film 2 is formed to cover all of the side surface and the bottom surface of the hole 11. In the present embodiment, the metal film 2 is formed of silver. However, as long as it is a metal such as copper, aluminum, gold, tungsten, iron, or nickel, or various alloys, the light emitted from the LED chip 4 is effectively applied. The material properties of the reflection can be.

The glass film 3 is made of glass having a refractive index higher than that of the light-transmitting resin layer 6, and has light transmissivity and gas barrier properties, and prevents the metal film 2 from coming into contact with the outside air to be oxidized or vulcanized. Further, as shown in FIG. 1, the glass film 3 is formed on the bottom surface of the hole 11 so as to have a through hole 31 in a portion where the LED chip 4 is mounted. Further, an electrode exposure hole is also formed in a portion where the anode 52 and the cathode 51 are provided.

As shown in FIGS. 1 and 2, the through hole 31 is formed to be larger than the LED chip 4 in plan view, and the LED wafer 4 is disposed substantially at the center thereof. Therefore, the through hole 31 is separated from the LED wafer 4 by a predetermined distance, and a gap is formed between the inner peripheral surface of the through hole 31 and the outer peripheral surface of the LED wafer 4, and the two are not in contact with each other. Therefore, the portion of the through hole 31 is exposed to the LED film 4 and the metal film 2 therearound. Further, the gap portion is filled with the light transmissive resin layer 6 described above.

The size of the aforementioned gap may be, for example, 5 μm or more and 500 μm or less. When the gap is small, the proportion of light incident on the glass film 3 can not be sufficiently reduced. On the other hand, if the gap is large, the oxidation and vulcanization of the metal film 2 are insufficient. Therefore, when the gap is 5 μm or more and 500 μm or less, the proportion of light incident on the glass film 3 can be reduced, the extraction efficiency of light can be improved, and the oxidation and vulcanization of the metal film 2 can be sufficiently prevented. In some cases, even if the gap is 5 μm or more, the LED wafer 4 is dry and difficult to mount with the glass film 3, so the gap is preferably 50 μm or more.

Further, the through hole 31 and the electrode exposure hole may be formed by, for example, performing a glass coating on the entire region on the metal film 2, and then mounting the aforementioned LED wafer 4 by etching or the like. The glass is removed where the anode 52 and the cathode 51 are disposed.

Thus, the aforementioned glass film 3 is coated with the aforementioned gold other than the periphery of the aforementioned LED wafer 4. Since the film 2 is prevented from coming into contact with the outside air, discoloration due to oxidation and vulcanization of the metal film 2 is less likely to occur, and the extraction efficiency of light from the LED chip 4 is not easily lowered. In other words, the light-emitting device 100 of the present embodiment is less prone to change over time, and can maintain a predetermined performance for a long period of time.

In addition, since a gap is formed between the inner circumferential surface of the through hole 31 of the glass film 3 and the outer circumferential surface of the LED wafer 4, light rays emitted from the LED chip 4 toward the substrate 1 side are not easily introduced as will be described later. To the glass film 3.

Therefore, the change of the metal film 2 over time by the glass film 3 can be made, and the light extraction efficiency is higher than conventionally.

Further, in the related art, a material having a large difference in thermal expansion coefficient between glass and metal is in contact with the upper and lower surfaces of the LED wafer 4, and excessive thermal stress is applied to the LED wafer 4 to cause cracks or the like. In the present embodiment, the LED wafer is used. 4 is only affected by the thermal deformation of the metal film 2 by the aforementioned gap, and the problem as described above does not occur. Further, since the LED wafer 4 is directly placed on the metal film 2, heat can be efficiently radiated to the substrate 1 side by the metal film 2. By such a matter, it is possible to prevent the light-emitting characteristics of the LED wafer 4 from being changed due to heat.

Further, in the present embodiment, the LED wafer 4 is covered with the light-transmitting resin layer 6, and the light-transmitting resin layer 6 is filled in the gap. Since the light-transmitting resin layer 6 is softer than glass, it is transparent. The resin layer 6 is not easy to apply thermal stress to the LED wafer 4, and further, even if it is applied, it is rather slight. Therefore, there is no problem that the light transmissive resin layer 6 applies thermal stress to the LED wafer 4 such as glass.

Finally, the LED chip 4 is disposed in the through hole 31, and the glass film 3 is separated from the LED chip 4, thereby improving light extraction efficiency.

Fig. 3 is a view showing a simulation result of a ray trajectory emitted from the LED chip 4A toward the substrate 1A side in the conventional light-emitting device 100A shown in Fig. 6(a). 4 is a simulation diagram showing a ray trajectory emitted from the LED chip 4 toward the substrate 1 side in the light-emitting device 100 of the embodiment. fruit. In addition, FIG. 5 shows that the LED wafer 4C is disposed in the through hole of the glass film 3C, and when the inner peripheral surface of the through hole is in contact with the outer peripheral surface of the LED chip 4C, the trajectory of the light emitted from the LED chip 4C toward the substrate side is shown. Simulation results. Further, in terms of the simulation conditions, the refractive indices of the glass films 3A, 3, and 3C, the translucent resin layers 6A, 6, and 6C and the LED chips 4A, 4, and 4C were set to 1.5, 1.4, and 1.7, respectively.

As shown in FIG. 3, when the LED chip 4A is placed on the glass film 3A, the light emitted from the LED chip 4A toward the substrate 1A is incident on the glass film 3A, and most of the incident light is due to the glass. The relationship between the refractive index of the film 3A and the translucent resin layer 6A is repeatedly reflected in the glass film 3A, and it becomes impossible to extract to the light irradiation side. That is, in the prior art, the amount of light introduced into the glass film 3A is lost, and the light extraction efficiency is lowered.

On the other hand, in the light-emitting device 100 of the present embodiment, since the glass film 3 does not exist in the vicinity of the periphery of the LED wafer 4, the amount of the gap is set to be emitted from the LED chip 4 toward the substrate 1 as shown in FIG. The light is reflected by the metal film 2 toward the light-irradiating side, and only a small amount of light is incident on the glass film 3. Therefore, it is understood that the amount of light repeatedly reflected in the glass film 3 due to the relationship between the refractive index of the glass film 3 and the light-transmitting resin layer 6 is small, and there is almost no light introduced into the glass film 3. In other words, in the light-emitting device 100 of the present embodiment, since the light incident on the glass film 3 itself can be reduced, the amount of light repeatedly reflected in the glass film 3 is of course reduced, and the light extraction efficiency can be improved.

Further, unlike the present embodiment, when the glass film 3C is brought into contact with the LED chip 4C without forming a gap between the inner peripheral surface of the through hole and the outer peripheral surface of the LED chip 4C (light-emitting device 100C), as shown in FIG. 5 As shown in the above, the light emitted from the vicinity of the periphery of the LED chip 4C is partially incident on the glass film 3C in the same manner as the light-emitting device 100A, and most of the incident light is refracted by the glass film 3C and the light-transmitting resin layer 6C. The reflection is repeated in the glass film 3C in relation to the rate. Therefore, even if a gap is not provided between the inner circumferential surface of the through hole and the outer circumferential surface of the LED wafer 4C, light loss due to the glass film 3C occurs, and the light extraction efficiency is lowered.

On the contrary, the mode of the light-emitting device 100 of the present embodiment is adopted in the through hole 31. A gap is formed between the inner peripheral surface and the outer peripheral surface of the LED wafer 4, and the amount of light introduced into the glass film 3 is first reduced, and it is found that the light extraction efficiency can be improved even when the glass film 3 is provided.

Other embodiments will be described below

In the above embodiment, the glass film is set as a plating film, and other materials having gas barrier properties may be formed as a plating film. Further, in terms of the composition of the glass, any material may be used as long as it is less likely to cause cracks or the like. In short, the metal film may be any material that can prevent external air contact and light transmissive properties for a long period of time.

Further, the shape of the LED chip, the wavelength of the emitted light, and the like are not particularly limited, and the present invention can be constituted by various LED chips. Further, a plurality of LED chips may be disposed in the holes instead of arranging one LED chip in the holes as in the above embodiment.

Further, in the above example, a person having a property of reflecting light is used as the metal film, and a person having light transmissivity and gas barrier property is used as the plating film, but it is not limited thereto, and the metal film or the plating film may not be used. Nature.

Further, various modifications or combinations of embodiments may be made without departing from the spirit and scope of the invention.

[Industry Utilization]

The present invention can utilize a light-emitting device which has a small change over time and a high light extraction efficiency.

1‧‧‧Substrate

2‧‧‧Metal film

3‧‧‧ coating

4‧‧‧LED chip

6‧‧‧Transparent resin layer

11‧‧‧ hole

31‧‧‧through holes

100‧‧‧Lighting device

Claims (4)

A light-emitting device, comprising: a substrate; a metal film formed on a surface of the substrate; an LED chip disposed on the metal film; and a plating film formed on the metal film; and the plating film is formed with: a through hole The LED chip is disposed inside the film thickness direction of the plating film; the through hole is formed to be larger than the LED chip in a plan view, and the outer peripheral surface of the LED chip and the inner peripheral surface of the through hole are formed There is a gap formed between them. The light-emitting device of claim 1, wherein the coating film is a glass film. The light-emitting device of claim 1, further comprising a light-transmitting resin layer covering the plating film and the LED wafer. The light-emitting device of claim 3, wherein the coating has a refractive index greater than a refractive index of the light-transmitting resin layer.