CN115621399A - Light emitting element - Google Patents

Abstract

A light emitting device includes a substrate, a metal plating layer and a light emitting chip. The substrate includes a top surface having an area A1. The metal coating is arranged on the top surface and has a total area A2. The light emitting chip is arranged on the metal plating layer and is provided with a bottom area A3, wherein the area ratio of (A2-A3)/A1 is 35-50%, so that the aging and color changing speed of the metal plating layer meets the aging and color changing speed specification.

Description

Light emitting element

technical field

The invention relates to a light emitting element.

Background technique

Light Emitting Diode (LED) is a light-emitting element made of semiconductor materials, which can convert electrical energy into light. It has the advantages of small size, high energy conversion efficiency, long life, and power saving, so it is widely used in various electronic products. The light source of the device.

LEDs with metal reflective layers often fail to achieve better light extraction efficiency due to structural factors, or the reflectivity of the metal reflective layer decreases due to aging and discoloration, resulting in a rapid decline in the overall brightness of the LED. In view of this, suppliers need various solutions to improve the light reflection efficiency of the metal reflective layer and slow down the speed of aging and discoloration.

Contents of the invention

The present invention proposes an innovative light-emitting element and its manufacturing method to solve the problems of the prior art.

In some embodiments of the present invention, a light emitting device includes a substrate, a metal coating and a light emitting chip. The substrate includes a top surface, and the top surface has an area A1. The metal coating is disposed on the top surface, and the metal coating has a total area A2. The light-emitting chip is disposed on the metal coating, and the light-emitting chip has a bottom area A3, wherein the area ratio of (A2-A3)/A1 is between 35% and 50%.

In some embodiments of the invention, the light reflectance of the metal coating is greater than the light reflectance of the top surface.

In some embodiments of the present invention, the light reflectance of the top surface is 80%-85%.

In some embodiments of the present invention, the light reflectance of the metal coating is 90%-99%.

In some embodiments of the present invention, the metal plating layer includes gold, silver, copper or platinum.

In some embodiments of the present invention, the light-emitting element further includes a first light-reflecting layer located on the top surface of the light-emitting chip.

In some embodiments of the present invention, the light-emitting element further includes a second light-reflecting layer located between the light-emitting chip and the substrate.

In some embodiments of the present invention, the first light reflective layer has a thickness T1, the second light reflective layer has a thickness T2, and T1 is smaller than T2.

In some embodiments of the present invention, the ratio of T1/T2 is greater than or equal to 0.55.

In some embodiments of the present invention, the reflectivity of the first light reflective layer is smaller than the reflectivity of the second light reflective layer.

In summary, the area of the metal reflective layer found in the present invention has a proportional relationship with the speed of aging and discoloration, and the optimal area ratio range of the metal reflective layer to the top surface of the substrate and the bottom area of the light-emitting chip is obtained through experiments, which can make The aging discoloration speed of the metal reflective layer complies with the aging discoloration speed specification, and the power and light shape of the emitted light also meet the requirements. In addition, the light-emitting chip has an upper and a lower light-reflecting layer to increase side light emission, so that the light-emitting element of the present invention can be used in a backlight module of a display with a small number, while still maintaining the same light uniformity.

The above-mentioned description will be described in detail in the following embodiments, and a further explanation will be provided for the technical solution of the present invention.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present invention more comprehensible, the accompanying drawings are described as follows:

FIG. 1 is a top view illustrating a light emitting element according to some embodiments of the present invention;

2 is a top view illustrating a light-emitting element according to a comparative example of the present invention;

3 is a cross-sectional view illustrating a light emitting element according to some embodiments of the present invention; and

FIG. 4 is a graph showing the simulation comparison of light-emitting lifetime attenuation of light-emitting elements according to some embodiments of the present invention.

【Symbol Description】

In order to make the above-mentioned and other purposes, features, advantages and embodiments of the present invention more obvious and easy to understand, the description of the attached symbols is as follows:

100: light emitting element

102: Substrate

102a: top surface

104: metal coating

104a: Plating area

104b: Plating area

106:Light-emitting chip

108a: the first light reflection layer

108b: the second light reflection layer

110: Packaging glue

200: light emitting element

202: Substrate

202a: top surface

204: metal plating

204a: Plating area

204b: Plating area

206:Light-emitting chip

detailed description

In order to make the description of the present invention more detailed and complete, reference may be made to the attached drawings and various embodiments described below, and the same numbers in the drawings represent the same or similar elements. On the other hand, well-known elements and steps have not been described in the embodiments in order to avoid unnecessarily limiting the invention.

In the implementation and claims, the description involving "electrical connection" can generally refer to an element being indirectly electrically coupled to another element through other elements, or an element is directly electrically connected without passing through other elements to another component.

In the embodiments and claims, unless the article is specifically limited in the context, "a" and "the" can generally refer to a single or plural.

In order to improve the light reflection efficiency of metal reflective layers (such as metal coatings) and slow down the speed of aging and discoloration, the inventors of this case studied whether the area of the metal reflective layer is related to the speed of aging and discoloration, and found that the metal reflective layer There is indeed a proportional relationship between the size of the area and the speed of aging and discoloration. The following examples will detail this finding.

Please refer to FIGS. 1 and 2 at the same time. FIG. 1 is a top view of a light emitting device 100 according to some embodiments of the present invention, and FIG. 2 is a top view of a light emitting device 200 according to a comparative example of the present invention. A light emitting device 100 includes a substrate 102 , a metal coating 104 and a light emitting chip 106 . In some embodiments of the present invention, the metal plating layer 104 includes gold (Au), silver (Ag), copper (Cu), platinum (Pt) or combinations thereof. In other embodiments of the present invention, the metal coating 104 includes aluminum (Al), indium (In), ruthenium (Ru), tin (Sn), zinc (Zn), titanium (Ti), lead (Pb), nickel ( Ni), chromium (Cr), magnesium (Mg), palladium (Pd), or combinations thereof. In some embodiments of the present invention, the light emitting chip 106 may be a light emitting diode chip, such as a red diode chip, a green diode chip or a blue diode chip. The substrate 102 includes a top surface 102a, and the top surface 102a has an area A1. The metal plating layer 104 is disposed on the top surface 102a. In some embodiments of the present invention, the metal plating layer 104 includes a plating layer region 104 a and a plating layer region 104 b that are insulated from each other. The metal plating layer 104 has a total area A2 (ie, the total area of the plating layer region 104 a and the plating layer region 104 b ). The light-emitting chip 106 is disposed on the larger plated area 104b, and the two electrodes of the light-emitting chip 106 are electrically connected to the plated area 104a and the plated area 104b respectively (for example, they are electrically connected to the plated area by using metal wires). The light emitting chip 106 has a bottom area A3.

The light emitting element 200 also has a configuration similar to the light emitting element 100 . Specifically, the light emitting device 200 includes a substrate 202 , a metal coating 204 and a light emitting chip 206 . In some embodiments of the present invention, the metal plating layer 204 includes gold (Au), silver (Ag), copper (Cu), platinum (Pt) or combinations thereof. In other embodiments of the present invention, the metal coating 204 includes aluminum (Al), indium (In), ruthenium (Ru), tin (Sn), zinc (Zn), titanium (Ti), lead (Pb), nickel ( Ni), chromium (Cr), magnesium (Mg), palladium (Pd), or combinations thereof. In some embodiments of the present invention, the light emitting chip 206 may be a light emitting diode chip, such as a red diode chip, a green diode chip or a blue diode chip. The substrate 202 includes a top surface 202a, and the top surface 202a has an area A1. The metal plating layer 204 is disposed on the top surface 202a. In some embodiments of the present invention, the metal plating layer 204 includes a plating layer region 204 a and a plating layer region 204 b that are insulated from each other. The metal plating layer 204 has a total area A2 (ie, the total area of the plating layer region 204 a and the plating layer region 204 b ). The light-emitting chip 206 is disposed on the larger plated area 204b, and the two electrodes of the light-emitting chip 206 are electrically connected to the plated area 204a and the plated area 204b respectively (for example, they are electrically connected to the plated area by using metal wires). The light emitting chip 206 has a bottom area A3.

The metal coating (104, 204) is used to provide better light reflectivity, so as to increase the overall light output power of the light-emitting element, so the light reflectivity of the metal coating (104, 204) needs to be greater than that of the light on the top surface of the substrate (102a, 202a) Reflectivity. In some embodiments of the present invention, the light reflectance of the top surface (102a, 202a) of the substrate is 80%-85%. In some embodiments of the present invention, the light reflectance of the metal coating (104, 204) is 90%-99%.

In the light-emitting element 200, the area ratio of the area A2/area A1 is greater than or equal to 60%, for example, the area ratio of the comparative example C1 is equal to 68%. In the light-emitting element 100, the area ratio of area A2/area A1 is between 40% and 55%, for example, the ratio of area A2/area A1 in embodiment E1 is 30%; the ratio of area A2/area A1 in embodiment E2 is 35%; the ratio of area A2/area A1 of embodiment E3 is 40%; the ratio of area A2/area A1 of embodiment E4 is 45%; the ratio of area A2/area A1 of embodiment E5 is 55%.

Please refer to FIG. 4 , which shows a comparison chart of simulated luminous lifetimes of light-emitting elements according to some embodiments of the present invention. The above-mentioned Comparative Example C1 and Examples E4-E5 are used for the simulation experiment of the luminous lifetime, and the three curves of the simulated luminous lifetime comparison graph of the light-emitting element shown in FIG. 4 can be obtained. The ratios of the area A2/area A1 of the embodiments E1-E3 are all less than or equal to 40%, because the metal coating with a small area cannot provide enough area to reflect the light emitted by the light-emitting chip 106, and cannot meet the requirements of the overall brightness, so they are not included. Evaluation of luminescence lifetime simulation experiments. It can be seen from Figure 4 that the light output power of Comparative Example C1 is attenuated by more than 50% when it operates at 85°C/60mA for less than 10,000 hours, which does not meet the standard of aging discoloration speed. Example E5 operates at 85°C/60mA for more than 10,000 hours when the light output power decays by more than 50%, which meets the aging discoloration speed specification. Example E4 is also operated at 85°C/60mA for more than 10,000 hours of luminous power to attenuate more than 50%, which meets the aging discoloration speed specification. The metal coating of embodiment E4 has slower aging discoloration speed than the metal coating of embodiment E5. Therefore, it is speculated that the smaller ratio of the area of the metal coating to the area of the top surface of the substrate can indeed slow down the rate of aging and discoloration. The inventors of this case concluded that the speed of aging and discoloration should be related to the area of the metal coating. Specifically, the larger the area of the metal coating, the more light energy emitted by the light-emitting chip is absorbed, so the overall aging and discoloration speed is accelerated, thereby reducing the light reflectivity.

Based on the results summarized above, the area of the metal coating 104 irradiated by the light emitted by the light-emitting chip has a strong correlation with the overall aging and discoloration speed, and the metal coating directly below the light-emitting chip cannot be directly irradiated by the light emitted by the light-emitting chip, so It should be deducted when calculating the area ratio. In some embodiments of the present invention, the ratio of (the total area A2 of the metal coating - the bottom area A3 of the light-emitting chip)/the area A1 of the top surface of the substrate is between 35% and 50% through the simulation verification of the embodiment, which can make the light emitting chip After more than 10,000 hours, the light output power will decay by more than 50% (under the operating condition of 85°C/60mA), which meets the specification of aging and discoloration speed.

Please refer to FIG. 3 , which shows a cross-sectional view of a light-emitting device according to some embodiments of the present invention, for example, a cross-sectional view along the section line 3 - 3 in FIG. 1 . In some embodiments of the present invention, the light-emitting element further includes a first light-reflecting layer 108a located on the top surface of the light-emitting chip 106, and the first light-reflecting layer 108a has a thickness T1. In some embodiments of the present invention, the light-emitting device further includes a second light-reflecting layer 108b located between the light-emitting chip 106 and the substrate 102, and the second light-reflecting layer has a thickness T2. More specifically, the second light reflection layer 108b is located between the light emitting chip 106 and the coating area 104a. The light-emitting element further includes an encapsulating adhesive 110 to integrally seal the light-emitting chip 106 , the first light-reflecting layer 108 a and the second light-reflecting layer 108 b on the top surface 102 a of the substrate 102 . In some embodiments of the present invention, the thickness T1 is smaller than the thickness T2, and the ratio of T1/T2 is greater than or equal to 0.55. In some embodiments of the present invention, the first light reflective layer 108 a has a reflectivity greater than 80% when the peak value of the wavelength of the incident light is in the range of 400-600 nanometers. The reflectance of the first light reflection layer 108a is smaller than the reflectance of the second light reflection layer 108b. In some embodiments of the present invention, the first light reflection layer 108a and the second light reflection layer 108b have the above-mentioned two light reflection layers. It is suitable for the light-emitting element in the backlight module of the display.

The area of the metal reflective layer found in the present invention has a proportional relationship with the speed of aging and discoloration, and the optimal area ratio range of the metal reflective layer to the top surface of the substrate and the bottom area of the light-emitting chip is obtained through experiments, which can make the aging of the metal reflective layer The speed of discoloration conforms to the specification of aging discoloration speed, and the power and shape of the light can also meet the requirements. In addition, the light-emitting chip has an upper and a lower light-reflecting layer to increase side light emission, so that the light-emitting element of the present invention can be used in a backlight module of a display with a small number, while still maintaining the same light uniformity.

Although the present invention has been disclosed above in terms of implementation, it is not intended to limit the present invention. Any skilled person may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection should be based on the scope defined by the appended claims.

Claims (10)

1. A light-emitting element, comprising:

a substrate including a top surface having an area A1;

a metal coating disposed on the top surface, the metal coating having a total area A2; and

a light emitting chip disposed on the metal plating layer, wherein the light emitting chip has a bottom area A3, and the area ratio of (A2-A3)/A1 is 35-50%.

2. The light-emitting element according to claim 1, wherein the metal plating layer has a light reflectance greater than that of the top surface.

3. The light-emitting element according to claim 1, wherein the top surface has a light reflectance of 80% to 85%.

4. The light-emitting element according to claim 1, wherein the metal plating layer has a light reflectance of 90% to 99%.

5. The light-emitting element according to claim 1, wherein the metal plating layer comprises gold, silver, copper, or platinum.

6. The light-emitting element according to claim 1, further comprising a first light-reflecting layer on a top surface of the light-emitting chip.

7. The light-emitting device according to claim 6, further comprising a second light-reflecting layer between the light-emitting chip and the substrate.

8. The light-emitting device according to claim 7, wherein the first reflector layer has a thickness T1, the second reflector layer has a thickness T2, and T1 is less than T2.

9. The light-emitting element according to claim 8, wherein a ratio of T1/T2 is 0.55 or more.

10. The light-emitting device according to claim 7, wherein a reflectivity of the first reflector layer is less than a reflectivity of the second reflector layer.

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