Packaging structure of multiple LED chips

Abstract

The utility model discloses a packaging structure of a plurality of LED chips. The packaging structure comprises a packaging substrate, a plurality of LED chips, a first reflection glue layer, a second reflection glue layer and a light-transmitting glue layer. A packaging area is planned on the surface of the packaging substrate, the plurality of LED chips and the first reflective glue layer are arranged on the packaging area, the LED chips are arranged at intervals, and the first reflective glue layer fills the area except the LED chips and covers the side walls of the LED chips; the light-transmitting glue layer is arranged on the first reflecting glue layer and the LED chip; the second reflective adhesive layer is arranged around the packaging area, and the top surface is flush with the top surface of the light-transmitting adhesive layer. Through the combined action of the first reflection glue layer and the second reflection glue layer, the reflection brightening effect is improved, and the higher light emitting efficiency is achieved under the same power consumption condition.

Description

Technical Field

[0001] This utility model belongs to the technical field of semiconductor packaging, specifically relating to a packaging structure for multiple LED chips. Background Technology

[0002] LED (Light Emitting Diode) packaging technology is a method of isolating and protecting LED chips from the external environment, while also increasing light output, dissipating heat, and ensuring electrical connectivity. LED packaging forms include DIP (Dual In-line Package), SMD (Surface Mount Device) packaging, and CSP (Chip-Scale Package). Continuous advancements in LED packaging technology have driven the development of LED technology, leading to its widespread application in lighting, displays, backlighting, and testing. With changing market demands, LED packaging is also evolving towards higher integration, smaller size, and better performance.

[0003] In traditional chip-level packaging, the back of the light-emitting chip is fixedly connected to the packaging substrate, and the surface is covered with a transparent packaging material. Light is emitted from the front and four sides. The light concentration from the front is poor, and the brightness of the product mainly depends on the performance of the LED chip itself, which is difficult to improve further. Moreover, when multiple chips are integrated on the same packaging substrate, the side light sources between the chips interfere with each other, reducing their performance. Utility Model Content

[0004] This invention addresses the shortcomings of existing technologies by providing an LED packaging structure.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A multi-LED chip packaging structure includes a packaging substrate, multiple LED chips, a first reflective adhesive layer, a second reflective adhesive layer, and a light-transmitting adhesive layer. A packaging area is planned on the surface of the packaging substrate. The multiple LED chips and the first reflective adhesive layer are disposed on the packaging area, wherein the LED chips are spaced apart, and the first reflective adhesive layer fills the area outside the LED chips and covers the sidewalls of each LED chip. The light-transmitting adhesive layer is disposed on the first reflective adhesive layer and the LED chips. The second reflective adhesive layer is disposed around the packaging area, and its top surface is flush with the top surface of the light-transmitting adhesive layer.

[0007] Optionally, the height of the first reflective adhesive layer is not higher than the top surface of the LED chip.

[0008] Optionally, the height of the first reflective adhesive layer gradually decreases from the top edge of the LED chip outwards, and the lowest point of the height of the first reflective adhesive layer filling the gap between adjacent LED chips is located in the interval.

[0009] Optionally, the height of the first reflective adhesive layer gradually decreases from the top edge of the LED chip outwards, and the lowest point of the first reflective adhesive layer, which fills the space between the LED chip and the second reflective adhesive layer, is located at the position where it contacts the second reflective adhesive layer.

[0010] Optionally, the width of the second reflective adhesive layer is 20–200 μm.

[0011] Optionally, the edge of the second reflective adhesive layer is flush with the edge of the encapsulation substrate.

[0012] Optionally, both the first and second reflective adhesive layers are white adhesives with a reflectivity of ≥95%.

[0013] Optionally, the plurality of LED chips have different emission wavelengths.

[0014] Optionally, the plurality of LED chips include green LED chips, red LED chips, and infrared LED chips.

[0015] Optionally, the LED chip is a conventional chip or a flip chip, electrically connected to the packaging substrate via top wire bonding or bottom pad bonding.

[0016] The beneficial effects of this utility model are as follows:

[0017] In the multi-LED chip packaging structure, the light is ultimately focused towards the center of the top surface through the combined action of the first and second reflective adhesive layers, which improves the reflection and brightness enhancement effect and achieves higher light output efficiency under the same power consumption conditions. When applied to the integration of LED chips with different emission wavelengths, it reduces mutual interference between LED chips. It can be formed through large-scale manufacturing processes, with high production efficiency and strong controllability.

[0018] Other features and beneficial effects of this invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this invention. Attached Figure Description

[0019] Figure 1 A cross-sectional schematic diagram of the packaging structure of the multi-LED chip in the embodiment;

[0020] Figure 2 This is a top view of the packaging structure of the multi-LED chip as an example (the light-transmitting adhesive layer is not shown in the figure);

[0021] Figure 3 This is a schematic diagram of the optical path of the multi-LED chip packaging structure in an embodiment.

[0022] Figure 4This is a schematic diagram illustrating the fabrication process of the multi-LED chip packaging structure in an embodiment.

[0023] Figure 5 This is a cross-sectional schematic diagram of the packaging structure of a multi-LED chip in the first comparative example;

[0024] Figure 6 This is a cross-sectional schematic diagram of the packaging structure of a multi-LED chip, as shown in the second comparative example. Detailed Implementation

[0025] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate understanding of the present invention, and their specific proportions can be adjusted according to design requirements. The vertical relationships of relative elements and the definitions of front / back in the graphics described herein should be understood by those skilled in the art to refer to the relative positions of the components; therefore, they can all be flipped to present the same component, and all of this should fall within the scope disclosed in this specification.

[0026] refer to Figure 1 and Figure 2 An embodiment of a multi-LED chip packaging structure includes a packaging substrate 1, multiple LED chips (two LED chips 2a and 2b are used as an example in the figure), a first reflective adhesive layer 3, a second reflective adhesive layer 4, and a light-transmitting adhesive layer 5. The surface of the packaging substrate 1 is planned with a packaging region A. The LED chips 2a and 2b and the first reflective adhesive layer 3 are disposed on the packaging region A, wherein the LED chips 2a and 2b are spaced apart. The first reflective adhesive layer 3 fills the area outside the LED chips 2a and 2b in the packaging region A and covers the sidewalls of the LED chips 2a and 2b, so that the LED chips 2a and 2b are surrounded by the first reflective adhesive layer 3. The light-transmitting adhesive layer 5 is disposed on the first reflective adhesive layer 3 and the LED chips 2a and 2b. The second reflective adhesive layer 4 is disposed around the packaging region A and its top surface is flush with the top surface of the light-transmitting adhesive layer 5, forming a double reflective layer structure.

[0027] Specifically, the height of the first reflective adhesive layer 3 is no higher than the top surface of LED chips 2a and 2b, and it must cover all sides of LED chips 2a and 2b. In actual installation, for LED chips 2a and 2b with the same or different heights, the interval between them is adjusted to ensure that the height of the first reflective adhesive layer 3 gradually decreases outward from the top edge of LED chips 2a and 2b, and the lowest point 31 of the first reflective adhesive layer 3 filling the space between LED chips 2a and 2b is located in the interval between them. Between LED chips 2a and 2b and the second reflective adhesive layer 4, the height of the first reflective adhesive layer 3 gradually decreases outward from the top edge of LED chips 2a and 2b, with the lowest point 32 located at the position where it connects with the second reflective adhesive layer 4. This ensures that the adhesive does not overflow onto the front surface of LED chips 2a and 2b while still achieving the desired side light emission effect.

[0028] The encapsulation area A is preferably located in the middle of the encapsulation substrate 1. The second reflective adhesive layer 4 surrounds the encapsulation area A to form a ring-shaped dam, the edge of which is flush with the edge of the encapsulation substrate 1. The width d of the ring is preferably 20 to 200 μm.

[0029] Both the first reflective adhesive layer 3 and the second reflective adhesive layer 4 are white adhesives with a reflectivity ≥95%. The white adhesive is any white adhesive disclosed in the prior art, such as white silicone resin, or a mixture of transparent encapsulant and 3%–5% white reflective powder, etc., and is not limited thereto. The light-transmitting adhesive layer 5 is a transparent encapsulant.

[0030] refer to Figure 3 With the above-mentioned double reflective layer, the light emitted by LED chips 2a and 2b can be reflected from the top surface by the first reflective adhesive layer 3. The optical fiber that diverges outward from the top surface is blocked by the second reflective adhesive layer 4, and the light is finally focused towards the center of the top surface by the combined effect of the second reflective adhesive layer 4 and the first reflective adhesive layer 3, which improves the reflection and brightening effect and achieves higher light output efficiency under the same power consumption conditions.

[0031] The aforementioned multi-LED chip packaging structure can be mass-produced during manufacturing, as described above. Figure 4 The LED chip can be a top-mounted or flip-chip, electrically connected to the packaging substrate via top wire bonding or bottom pad bonding. When using wire bonding, the bottom surface can be fixed to the packaging substrate surface with die-attach adhesive. Then, a first reflective adhesive layer is applied to the surface of the packaging substrate outside the chip, followed by a transparent adhesive layer. The transparent adhesive layer is cut to create a secondary encapsulation channel, forming a second reflective adhesive layer. After grinding to remove the second reflective adhesive layer from the transparent adhesive layer, individual products are cut to form the package structure. The cut is located at the center of the channel, resulting in a structure where the second reflective adhesive layer surrounds the outer layer, with the top surface flush with the transparent adhesive layer and the edges flush with the substrate edges. Transparent die-attach adhesive can be used, and the packaging substrate PAD plating is a silver plating layer, which can further improve bottom light reflection below the chip.

[0032] In the aforementioned multi-LED chip packaging structure, the LED chips can have the same or different emission wavelengths. In one embodiment, the LED chip package for a detection unit in portable wearable devices such as watches and wristbands includes a red LED chip, an infrared LED chip, and a green LED chip, where the red / infrared light is used for blood oxygen testing and the green light is used for heart rate measurement. The aforementioned dual-reflective layer effectively avoids mutual interference between light rays, improves their respective light emission efficiency, and thus improves detection accuracy with lower energy consumption.

[0033] The first comparative example differs from the above embodiments in that, as Figure 5 As shown, it does not have a first reflective adhesive layer. Under the same conditions, the brightness comparison of LED chips with different emission wavelengths in the above embodiments and this comparative example is shown in the table below:

[0034]

[0035] As can be seen, compared with the encapsulation structure without the first reflective adhesive layer, the brightness of LED chips with different emission wavelengths in the encapsulation structure of the embodiment is significantly improved.

[0036] The second comparative example differs from the above embodiment in that, as Figure 6 As shown, it does not have a second reflective adhesive layer. Under the same conditions, the brightness comparison of LED chips with different emission wavelengths in the above embodiments and this comparative example is shown in the table below:

[0037]

[0038] As can be seen, compared with the encapsulation structure without a second reflective adhesive layer, the brightness of LED chips with different emission wavelengths in the encapsulation structure of the embodiment is significantly improved.

[0039] The third comparative example differs from the above embodiments in that its first reflective adhesive layer overflows onto the top surface of the chip, or the amount of adhesive is too small to completely cover the encapsulation area A. Under the same conditions, the brightness comparison of LED chips with different emission wavelengths in the above embodiments and this comparative example is shown in the table below:

[0040]

[0041] The embodiment effectively enhances the luminous brightness of LED chips with various emission wavelengths by combining the first and second reflective adhesive layers.

[0042] The above embodiments are only used to further illustrate a multi-LED chip packaging structure of the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-LED chip packaging structure, characterized in that: The package includes a packaging substrate, multiple LED chips, a first reflective adhesive layer, a second reflective adhesive layer, and a light-transmitting adhesive layer. The surface of the packaging substrate is planned with a packaging area. Multiple LED chips and the first reflective adhesive layer are disposed on the packaging area, wherein the LED chips are spaced apart. The first reflective adhesive layer fills the area outside the LED chips and covers the sidewalls of each LED chip. The light-transmitting adhesive layer is disposed on the first reflective adhesive layer and the LED chips. The second reflective adhesive layer is disposed around the packaging area and its top surface is flush with the top surface of the light-transmitting adhesive layer.

2. The multi-LED chip packaging structure according to claim 1, characterized in that: The height of the first reflective adhesive layer is not higher than the top surface of the LED chip.

3. The multi-LED chip packaging structure according to claim 2, characterized in that: The height of the first reflective adhesive layer gradually decreases from the top edge of the LED chip outwards, and the lowest point of the height of the first reflective adhesive layer filling the gap between adjacent LED chips is located in the gap.

4. The multi-LED chip packaging structure according to claim 2, characterized in that: The height of the first reflective adhesive layer gradually decreases from the top edge of the LED chip outwards, and the lowest point of the first reflective adhesive layer, which fills the space between the LED chip and the second reflective adhesive layer, is located at the position where it connects with the second reflective adhesive layer.

5. The multi-LED chip packaging structure according to claim 1, characterized in that: The width of the second reflective adhesive layer is 20–200 μm.

6. The multi-LED chip packaging structure according to claim 1, characterized in that: The edge of the second reflective adhesive layer is flush with the edge of the encapsulation substrate.

7. The multi-LED chip packaging structure according to claim 1, characterized in that: Both the first and second reflective adhesive layers are white adhesive, and the reflectivity of the white adhesive is ≥95%.

8. The multi-LED chip packaging structure according to claim 1, characterized in that: The multiple LED chips have different emission wavelengths.

9. The multi-LED chip packaging structure according to claim 8, characterized in that: The plurality of LED chips include green LED chips, red LED chips, and infrared LED chips.

10. The multi-LED chip packaging structure according to claim 1, characterized in that: The LED chip is either a standard chip or a flip chip, and is electrically connected to the packaging substrate via top wire bonding or bottom pad bonding.

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