Light emitting element

Abstract

A light emitting element includes a substrate, a metal plating layer, and a light emitting chip. The substrate includes a top surface having an area A1. The metal plating layer is disposed on the top surface, and has a total area A2. The light emitting chip is disposed on the metal plating layer, and has a bottom area A3. An area ratio of (A2-A3) / A1 is between 35-50%, so that the aging discoloration speed of the metal plating layer meets the specification of the aging discoloration speed.

Description

Technical Field

[0001] This invention relates to a light-emitting element. Background Technology

[0002] Light-emitting diodes (LEDs) are light-emitting elements made of semiconductor materials that can convert electrical energy into light. They have advantages such as small size, high energy conversion efficiency, long lifespan, and energy saving, and are therefore widely used as light sources in various electronic devices.

[0003] Light-emitting diodes (LEDs) with metal reflective layers often fail to achieve optimal light extraction efficiency due to structural factors, or the reflectivity of the metal reflective layer decreases due to aging and discoloration, leading to a rapid decline in the overall brightness of the LED. Therefore, suppliers require various solutions to improve the light reflection efficiency of the metal reflective layer and slow down the rate of aging and discoloration. Summary of the Invention

[0004] This invention proposes an innovative light-emitting element and its manufacturing method, solving the problems of prior art.

[0005] In some embodiments of the present invention, a light-emitting element includes a substrate, a metal plating layer, and a light-emitting chip. The substrate includes a top surface with an area A1. The metal plating layer is disposed on the top surface and has a total area A2. The light-emitting chip is disposed on the metal plating layer and has a bottom area A3, wherein the area ratio of (A2-A3) / A1 is between 35% and 50%.

[0006] In some embodiments of the present invention, the light reflectivity of the metal coating is greater than that of the top surface.

[0007] In some embodiments of the present invention, the light reflectivity of the top surface is 80% to 85%.

[0008] In some embodiments of the present invention, the light reflectance of the metal coating is 90% to 99%.

[0009] In some embodiments of the present invention, the metal plating comprises gold, silver, copper or platinum.

[0010] 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.

[0011] 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.

[0012] In some embodiments of the present invention, the first light-reflecting layer has a thickness T1, and the second light-reflecting layer has a thickness T2, wherein T1 is less than T2.

[0013] In some embodiments of the present invention, the ratio of T1 / T2 is greater than or equal to 0.55.

[0014] In some embodiments of the present invention, the reflectivity of the first light-reflecting layer is less than that of the second light-reflecting layer.

[0015] In summary, this invention demonstrates a direct proportional relationship between the area of ​​the metal reflective layer and its aging and discoloration rate. Experiments have yielded an optimal area ratio range between the metal reflective layer and the top surface of the substrate, as well as the bottom area of ​​the light-emitting chip. This ensures that the aging and discoloration rate of the metal reflective layer meets the required specifications, while also meeting the requirements for light output power and pattern. Furthermore, the light-emitting chip features upper and lower reflective layers to enhance side light emission, allowing the light-emitting elements of this invention to be used in a smaller number of backlight modules in displays while maintaining the same light uniformity.

[0016] The above description will be given in detail below with reference to the embodiments, and a further explanation of the technical solution of the present invention will be provided. Attached Figure Description

[0017] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the accompanying drawings are described below:

[0018] Figure 1 This is a top view illustrating a light-emitting element according to some embodiments of the present invention;

[0019] Figure 2 This is a top view illustrating a light-emitting element according to a comparative example of the present invention;

[0020] Figure 3 This is a cross-sectional view illustrating a light-emitting element according to some embodiments of the present invention; and

[0021] Figure 4 This is a comparison diagram illustrating the simulated decay of the luminous lifetime of light-emitting elements according to some embodiments of the present invention.

[0022] [Symbol Explanation]

[0023] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the appended symbols are explained as follows:

[0024] 100: Light-emitting element

[0025] 102:Substrate

[0026] 102a: Top surface

[0027] 104: Metallic coating

[0028] 104a: Coating area

[0029] 104b: Coating area

[0030] 106: Light-emitting chip

[0031] 108a: First light-reflecting layer

[0032] 108b: Second light-reflecting layer

[0033] 110: Encapsulating adhesive material

[0034] 200: Light-emitting element

[0035] 202:Substrate

[0036] 202a: Top surface

[0037] 204: Metallic coating

[0038] 204a: Coating area

[0039] 204b: Coating area

[0040] 206: Light-emitting chip Detailed Implementation

[0041] To provide a more detailed and complete description of the invention, reference can be made to the accompanying drawings and the various embodiments described below, in which the same numbers represent the same or similar elements. Furthermore, well-known elements and steps are not described in the embodiments to avoid unnecessarily limiting the invention.

[0042] In the embodiments and claims, the description of “electrical connection” can refer to an element being indirectly electrically coupled to another element through other elements, or an element being directly electrically connected to another element without needing to go through other elements.

[0043] In the embodiments and claims, unless otherwise specified in the text, “a” and “the” may refer to a single or multiple entities.

[0044] To improve the light reflection efficiency of a metal reflective layer (such as a metal coating) and slow down the rate of aging and discoloration, the inventors of this invention investigated whether the area of ​​the metal reflective layer was related to its aging and discoloration rate. Experimental results showed that the area of ​​the metal reflective layer is indeed directly proportional to its aging and discoloration rate. The following embodiments will detail this finding.

[0045] Please refer to the following at the same time Figure 1 , 2 , Figure 1 This is a top view illustrating a light-emitting element 100 according to some embodiments of the present invention. Figure 2This is a top view illustrating a light-emitting element 200 according to a comparative example of the present invention. The light-emitting element 100 includes a substrate 102, a metal plating layer 104, and a light-emitting chip 106. In some embodiments of the present invention, the metal plating layer 104 comprises gold (Au), silver (Ag), copper (Cu), platinum (Pt), or a combination thereof. In other embodiments of the present invention, the metal plating layer 104 comprises aluminum (Al), indium (In), ruthenium (Ru), tin (Sn), zinc (Zn), titanium (Ti), lead (Pb), nickel (Ni), chromium (Cr), magnesium (Mg), palladium (Pd), or a combination 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 having 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 plating regions 104a and 104b that are insulated from and separated from each other. The metal plating layer 104 has a total area A2 (i.e., the combined area of ​​plating regions 104a and 104b). The light-emitting chip 106 is disposed on the larger plating region 104b, and the two electrodes of the light-emitting chip 106 are electrically connected to the plating regions 104a and 104b respectively (e.g., electrically connected to the plating regions respectively by means of wire bonding). The light-emitting chip 106 has a bottom area A3.

[0046] The light-emitting element 200 also has a similar configuration to the light-emitting element 100. Specifically, the light-emitting element 200 includes a substrate 202, a metal plating layer 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 plating layer 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, which 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 plating regions 204a and 204b that are insulated from and separated from each other. The metal plating layer 204 has a total area A2 (i.e., the combined area of ​​plating regions 204a and 204b). The light-emitting chip 206 is disposed on the larger plating region 204b, and the two electrodes of the light-emitting chip 206 are electrically connected to the plating regions 204a and 204b respectively (e.g., electrically connected to the plating regions respectively by means of wire bonding). The light-emitting chip 206 has a bottom area A3.

[0047] The metal plating (104, 204) is used to provide better light reflectivity, thereby improving the overall light output power of the light-emitting element. Therefore, the light reflectivity of the metal plating (104, 204) needs to be greater than that of the top surface (102a, 202a) of the substrate. In some embodiments of the present invention, the light reflectivity of the top surface (102a, 202a) of the substrate is 80% to 85%. In some embodiments of the present invention, the light reflectivity of the metal plating (104, 204) is 90% to 99%.

[0048] In the light-emitting element 200, the area ratio of area A2 to area A1 is greater than or equal to 60%, for example, the area ratio of Comparative Example C1 is 68%. In the light-emitting element 100, the area ratio of area A2 to area A1 is between 40% and 55%, for example, the area ratio of area A2 to area A1 in Example E1 is 30%; the area ratio of area A2 to area A1 in Example E2 is 35%; the area ratio of area A2 to area A1 in Example E3 is 40%; the area ratio of area A2 to area A1 in Example E4 is 45%; and the area ratio of area A2 to area A1 in Example E5 is 55%.

[0049] Please refer to Figure 4 The diagram illustrates a comparison of simulated luminous lifetimes of light-emitting elements according to some embodiments of the present invention. By conducting simulated luminous lifetime experiments on Comparative Example C1 and Examples E4-E5, the results can be obtained. Figure 4 The three curves in the simulated luminous lifetime comparison chart of the light-emitting elements are shown. In Examples E1 to E3, the area A2 / area A1 ratio is less than or equal to 40%. Because the small area of ​​the metal plating layer cannot provide sufficient area to reflect the light emitted by the light-emitting chip 106, it cannot meet the overall brightness requirements and is therefore not included in the evaluation of the luminous lifetime simulation experiment. Figure 4 It can be seen that Comparative Example C1, operating at 85℃ / 60mA, experienced a light output power degradation of over 50% in less than 10,000 hours, failing to meet the aging and discoloration rate specifications. Example E5, operating at 85℃ / 60mA, only experienced a light output power degradation of over 50% after more than 10,000 hours, meeting the aging and discoloration rate specifications. Example E4 also operated at 85℃ / 60mA for over 10,000 hours before experiencing a light output power degradation of over 50%, meeting the aging and discoloration rate specifications. The metal plating of Example E4 exhibited a slower aging and discoloration rate than the metal plating of Example E5. This suggests that a smaller ratio of the metal plating area to the top surface area of ​​the substrate can indeed slow down the aging and discoloration rate. The inventors of this invention conclude that the aging and discoloration rate is related to the area of ​​the metal plating. Specifically, a larger metal plating area absorbs more light energy emitted by the light-emitting chip, thus accelerating the overall aging and discoloration rate and consequently reducing light reflectivity.

[0050] Based on the above conclusions, the area of ​​the metal plating 104 irradiated by the light emitted by the light-emitting chip is strongly correlated with the overall aging and discoloration rate. However, the metal plating directly beneath the light-emitting chip cannot be directly irradiated by the light emitted by the chip, so it should be deducted when calculating the area ratio. In some embodiments of this invention, simulation verification shows that the ratio of (total area of ​​the metal plating A2 - bottom area of ​​the light-emitting chip A3) / top surface area of ​​the substrate A1 is between 35% and 50%. This ensures that the emitted light power only decreases by more than 50% after more than 10,000 hours of illumination (under operating conditions of 85℃ / 60mA), which meets the specifications for aging and discoloration rate.

[0051] Please refer to Figure 3 It illustrates a cross-sectional view of a light-emitting element according to some embodiments of the present invention, for example, along... Figure 1 The cross-sectional view is shown in section line 3-3. 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, the first light-reflecting layer 108a having a thickness T1. In some embodiments of the present invention, the light-emitting element 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 having a thickness T2. More specifically, the second light-reflecting layer 108b is located between the light-emitting chip 106 and the plating region 104a. The light-emitting element further includes an encapsulating adhesive 110 that seals the light-emitting chip 106, the first light-reflecting layer 108a, and the second light-reflecting layer 108b integrally onto the top surface 102a of the substrate 102. In some embodiments of the present invention, the thickness T1 is less 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-reflecting layer 108a has a reflectivity greater than 80% when the peak value of the incident light wavelength is between 400 and 600 nanometers. The reflectivity of the first light-reflecting layer 108a is less than that of the second light-reflecting layer 108b. In some embodiments of the present invention, the light emitted by the light-emitting element having the first light-reflecting layer 108a and the second light-reflecting layer 108b has a large divergence angle and can have a good light pattern, making it suitable as a light-emitting element in the backlight module of a display.

[0052] The present invention discovers a direct proportional relationship between the area of ​​the metal reflective layer and its aging and discoloration rate. Experiments have yielded an optimal area ratio range between the metal reflective layer and the top surface of the substrate, and the bottom area of ​​the light-emitting chip. This ensures that the aging and discoloration rate of the metal reflective layer meets the required specifications, and that the emitted light power and pattern also meet the requirements. Furthermore, the light-emitting chip has upper and lower reflective layers to increase side light emission, allowing the light-emitting elements of the present invention to be used in a smaller number of backlight modules of displays while still maintaining the same light uniformity.

[0053] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the appended claims.

Claims

1. A light-emitting element, characterized in that, Include: A substrate includes a top surface having an area A1; A metal coating is disposed on the top surface, the metal coating having a total area A2, wherein the metal coating is not in contact with the periphery of the top surface, the light reflectivity of the metal coating is greater than the light reflectivity of the top surface, and the metal coating includes a first coating region and a second coating region that are insulated from each other; and A light-emitting chip is disposed on the second plating area of ​​the metal plating layer, which has a larger area. The light-emitting chip has a bottom area A3, wherein the area ratio of (A2-A3) / A1 is between 35% and 50%.

2. The light-emitting element according to claim 1, characterized in that, The light reflectance of the top surface is 80%–85%.

3. The light-emitting element according to claim 1, characterized in that, The light reflectance of this metal coating is 90%–99%.

4. The light-emitting element according to claim 1, characterized in that, The metal plating contains gold, silver, copper, or platinum.

5. The light-emitting element according to claim 1, characterized in that, It also includes a first light-reflecting layer located on the top surface of the light-emitting chip.

6. The light-emitting element according to claim 5, characterized in that, It also includes a second light-reflecting layer located between the light-emitting chip and the substrate.

7. The light-emitting element according to claim 6, characterized in that, The first light-reflecting layer has a thickness T1, and the second light-reflecting layer has a thickness T2, where T1 is less than T2.

8. The light-emitting element according to claim 7, characterized in that, The ratio of T1 / T2 is greater than or equal to 0.

55.

9. The light-emitting element according to claim 6, characterized in that, The reflectivity of the first light-reflecting layer is less than that of the second light-reflecting layer.

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