A multi-led chip stacked light source package structure and a method for manufacturing the same

Abstract

The application belongs to the technical field of LED light source packaging structure, and particularly relates to a multi-LED chip stacked light source packaging structure and a preparation method thereof. Through the multi-LED chip stacked light source packaging structure design, multiple second LED chips are fixed on the upside of a first LED chip, and a fluorescent powder layer is arranged on the first LED chip and the second LED chips respectively, so that light of multiple different color temperatures can be mixed in the vertical direction to improve the light mixing effect. Through the arrangement of more than three LED chips and the adjustment of the light emitting brightness of different chips, light of different color temperatures can be formed through light mixing, and the light emitting chroma can be kept on the Planck locus through dimming to ensure the natural light emission and reduce the distortion of colors. Meanwhile, the packaging structure is provided with reflective glue around the LED chips to reflect the side light emission and enhance the central light emission, so that the light emission and light mixing of the multi-LED chips are further uniform.

Description

Technical Field

[0001] This invention belongs to the field of LED light source packaging structure technology, specifically relating to a light source packaging structure with multiple stacked LED chips and its preparation method. Background Technology

[0002] LED light sources are devices that emit light through light-emitting diodes (LEDs). An LED is a semiconductor material; when an electric current is applied, charge carriers recombine within the semiconductor material, releasing energy and producing visible light. LED light sources are characterized by high efficiency, long lifespan, low energy consumption, adjustable brightness, and rapid on / off operation, making them widely used in lighting, displays, and indicators. They are more energy-efficient and environmentally friendly than traditional light sources such as incandescent and fluorescent lamps, and can achieve a variety of colors and brightness levels, thus finding widespread application in indoor lighting, automotive lighting, television screens, and electronic device backlighting.

[0003] Different color temperatures of light sources can bring different lighting effects and give people different visual experiences. With the improvement of people's living standards, existing manufacturers have developed LED light sources with adjustable color temperature. Traditional adjustable color temperature LED light sources generally set two LED chips with different color temperatures (usually 2700K and 6500K) to mix the light, and control the brightness of the two LED chips respectively to achieve the adjustment of color temperature and brightness.

[0004] For example, Chinese utility model patent CN205428921U discloses a dual-color-temperature LED packaging structure that fixes two LED chips of different color temperatures onto the same substrate, enabling the generation of light with different color temperatures. However, the LED light source with this packaging structure mixes the light from the two color-temperature chips, and when adjusting the color temperature, the chromaticity of the light deviates from the Planck trajectory, resulting in a visual difference between the light and natural light, causing color distortion when used for illumination. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defect of unnatural light output caused by mixing light of two color temperatures in the existing adjustable color temperature LED light source, thereby providing a light source packaging structure of multiple LED chip stacks and its preparation method.

[0006] A light source packaging structure with multiple LED chips stacked includes a substrate, a phosphor layer, a reflective adhesive, a transparent adhesive, a first LED chip, and multiple second LED chips; Multiple pads are provided on the upper side of the substrate; The first LED chip is fixed to the upper side of the substrate, and the electrodes of the first LED chip are electrically connected to the pads; Multiple second LED chips are fixed on the upper side of the first LED chip, and the electrodes of the first LED chip are electrically connected to the pads; The reflective adhesive is fixed to the upper side of the substrate, surrounding the first LED chip, and the inner side is inclined to form a pit. The phosphor layer includes a first phosphor layer and a second phosphor layer; the first phosphor layer and the second LED chip cover the upper side of the first LED chip, and the first phosphor layer covers the upper side of the reflective adhesive; the second phosphor layer covers the upper side of the first phosphor layer and the second LED chip, and the second phosphor layer surrounds the first LED chip. The transparent adhesive fills the cavity formed by the first LED chip, the inner side of the reflective adhesive, and the first phosphor layer.

[0007] Furthermore, the first LED chip is a flip-chip LED chip.

[0008] Furthermore, the second LED chip is a standard LED chip.

[0009] Furthermore, the electrodes on the upper side of the second LED chip are electrically connected to the pads on the upper side of the substrate via gold wires.

[0010] Furthermore, the first LED chip and the plurality of second LED chips are electrically connected to the plurality of different pads respectively.

[0011] Furthermore, the reflective adhesive is inclined on the outside, and the inclined surface formed by the inclination is inclined upward.

[0012] Furthermore, the phosphor layer covers the outer side of the reflective adhesive and extends to the upper side of the substrate.

[0013] Furthermore, the first LED chip and the second LED chip have different emission color temperature values, and the emission colorimetric values ​​of the multiple second LED chips are different.

[0014] Furthermore, it also includes a lens, which is fixed to the upper side of the substrate and surrounds the first LED chip, the second LED chip, reflective adhesive, transparent adhesive and phosphor layer.

[0015] The fabrication method of the multi-LED chip stacked light source packaging structure described above includes the following steps: Step S1: Prepare a fluorescent film; Step S2: Cut the fluorescent film to form multiple first phosphor layers, and form an opening in each first phosphor layer corresponding to the size of each second LED chip; Step S3: Fix the first LED chip on the upper side of the substrate, apply the transparent adhesive to the upper side of the first LED chip and fix the first phosphor layer, and squeeze the first phosphor layer so that the transparent adhesive surrounds the first LED chip. Step S4: Fix the second LED chip in the opening of the first phosphor layer on the upper side of the first LED chip; Step S5: Fix the reflective adhesive to the upper side of the substrate, the reflective adhesive surrounding the first LED chip; Step S6: Cover the upper side of the first phosphor layer and the upper side of the second LED chip with a second phosphor layer; Step S7: Cut the substrate to form a single light source package structure.

[0016] Beneficial effects: 1. This invention utilizes a multi-LED chip stacked light source packaging structure design. Multiple second LED chips are fixed on top of a first LED chip, and phosphor layers are respectively applied to the first and second LED chips. This enables the mixing of light of various color temperatures in the vertical direction, enhancing the mixing effect. Furthermore, by using three or more LED chips and adjusting the brightness of each chip, not only can different color temperatures be achieved through light mixing, but the output color temperature can also be maintained on the Planck locus, ensuring natural light output and reducing color distortion. Simultaneously, reflective adhesive is applied around the LED chips to reflect side light and enhance center light output, further ensuring uniform light mixing across the multiple LED chips.

[0017] 2. By tilting the outer side of the reflective adhesive and covering the outer side of the reflective adhesive and the upper side of the substrate with a phosphor layer, the present invention can reflect light through the reflective adhesive and the substrate and excite more phosphor, thereby improving the luminous efficiency of the light source; by setting a lens on the upper side of the substrate, the light can be focused, further improving the light mixing effect. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 2 This is a top view of the overall structure of the present invention; Figure 3This is a schematic structural diagram of the preparation method of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Substrate; 21. First phosphor layer; 22. Second phosphor layer; 3. Reflective adhesive; 4. Transparent adhesive; 51. First LED chip; 52. Second LED chip; 6. Gold wire; 7. Lens. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0022] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0026] Example 1: Reference Figure 1 and Figure 2 As shown, this embodiment provides a light source packaging structure with multiple stacked LED chips, including a substrate 1, a phosphor layer, a reflective adhesive 3, a transparent adhesive 4, a first LED chip 51, and multiple second LED chips 52; multiple pads are provided on the upper side of the substrate 1; the first LED chip 51 is fixed to the upper side of the substrate 1, and the electrodes of the first LED chip 51 are electrically connected to the pads; multiple second LED chips 52 are fixed to the upper side of the first LED chip 51, and the electrodes of the first LED chip 51 are electrically connected to the pads; the reflective adhesive 3 is fixed to the upper side of the substrate 1, surrounding the first LED chip 51. The transparent adhesive 4 fills the cavity formed by the first LED chip 51, the inner side of which is inclined to form a pit; the phosphor layer includes a first phosphor layer 21 and a second phosphor layer 22; the first phosphor layer 21 and the second LED chip 52 cover the upper side of the first LED chip 51, and the first phosphor layer 21 covers the upper side of the reflective adhesive 3; the second phosphor layer 22 covers the upper side of the first phosphor layer 21 and the second LED chip 52, and the second phosphor layer 22 surrounds the periphery of the first LED chip 51; the transparent adhesive 4 fills the cavity formed by the first LED chip 51, the inner side of the reflective adhesive 3 and the first phosphor layer 21.

[0027] This embodiment employs a multi-LED chip stacked light source packaging structure design. Multiple second LED chips 52 are fixed on the upper side of the first LED chip 51, and phosphor layers are respectively set on the first LED chip 51 and the second LED chip 52. This enables the mixing of light of various different color temperatures in the vertical direction, improving the mixing effect. Furthermore, by setting three or more LED chips and adjusting the luminous brightness of different chips, it is possible not only to achieve the mixing of light to form light of different color temperatures, but also to keep the color of the emitted light on the Planck locus, ensuring natural light emission and reducing color distortion. At the same time, this packaging structure sets reflective adhesive 3 around the LED chips, which can reflect the side light emission and enhance the center light emission, thereby further making the light emission and mixing of multiple LED chips more uniform.

[0028] Specifically, in this embodiment, two second LED chips 52 are provided, and the first LED chip 51 is a flip-chip LED chip, while the second LED chip 52 is a conventional LED chip. The first LED chip 51 is a flip-chip LED chip, which can be connected to the electrode at the bottom, uses a gold-wire-free process, and has sapphire crystal on the top, which has high strength so that die bonding on the top will not physically damage the chip, facilitates the stacking of its upper structure, and also has a high thermal conductivity, which facilitates heat dissipation of the chip above; the second LED chip 52 is a conventional LED chip, which can be connected to the top electrode through gold wire 6 and can dissipate heat directly through bottom contact.

[0029] In this embodiment, the electrode on the upper side of the second LED chip 52 is electrically connected to the pad on the upper side of the substrate 1 via gold wire 6; the electrode on the lower side of the first LED chip 51 is directly soldered to the pad on the upper side of the substrate 1.

[0030] The first LED chip 51 and multiple second LED chips 52 are electrically connected to multiple different pads, thereby enabling independent control of the power supply voltage of each first LED chip 51 and second LED chip 52, thus flexibly achieving color temperature and brightness adjustment. Specifically, pads are provided on the lower side of the substrate 1 corresponding to the upper side, and the positive and negative terminals of one first LED chip 51 and two second LED chips 52 are electrically connected to two pads at the bottom, facilitating electrical connection between the package structure and external devices. As a further improvement of this embodiment, a heat dissipation pad is also provided on the lower side of the substrate 1 to improve the heat dissipation performance of the package structure.

[0031] As a further improvement to this embodiment, the reflective adhesive 3 is inclined on its outer side, and the inclined surface formed is inclined upward. The phosphor layer covers the outer side of the reflective adhesive 3 and extends to the upper side of the substrate 1. By making the outer side of the reflective adhesive 3 inclined and covering the outer side of the reflective adhesive 3 and the upper side of the substrate 1 with the phosphor layer, the present invention can reflect light through the reflective adhesive 3 and the substrate 1, and excite more phosphor, thereby improving the luminous efficacy of the light source. As a further improvement to this embodiment, a lens 7 is also included. The lens 7 is fixed to the upper side of the substrate 1 and surrounds the first LED chip 51, the second LED chip 52, the reflective adhesive 3, the transparent adhesive 4, and the phosphor layer. By setting the lens 7 on the upper side of the substrate 1, light focusing is achieved, further improving the light mixing effect. In this embodiment, the lens 7 is a hemispherical lens with a smooth surface.

[0032] The first LED chip 51 and the second LED chip 52 have different emission color temperatures, and the emission chromaticity values ​​of the multiple second LED chips 52 are different. In this embodiment, the first LED chip 51 is a warm-colored LED chip, and the second LED chip 52 is a cool-colored LED chip. Preferably, the emission color temperature of the first LED chip 51 is 2700K, the emission color temperature of both second LED chips 52 is 6500K, and in the CIE 1931 color space chromaticity diagram, after passing through the corresponding phosphor layer, the emission chromaticity of the first LED chip 51 and one of the second LED chips 52 both fall on the Planck locus, while the emission chromaticity of the other second LED chip 52 falls above the Planck locus and is in a greenish position. Therefore, this light source packaging structure can provide a continuous light source output with color temperatures ranging from 2700K to 6500K on the Planck locus; when a 2700K color temperature output is required, the first LED chip 51 is lit; when a 6500K color temperature output is required, the first second LED chip 52 is lit; when a color temperature output between 2700K and 6500K is required, the brightness of the three LED chips is adjusted to mix the light and achieve the output.

[0033] In other embodiments of the present invention, after passing through the corresponding phosphor layer, the emitted chromaticity of the three LED chips does not fall on the Planck locus, and the emitted chromaticity of the three LED chips is different on the same side of the Planck locus, thereby adjusting the brightness of the three LED chips can achieve mixed light output with different color temperatures and brightness on the Planck locus.

[0034] As a preferred embodiment, the reflective adhesive 3 has a height of 100-180 μm, and the reflective adhesive 3 forms an angle of 30-60 degrees with the periphery of the first LED chip 51.

[0035] In this embodiment, the bottom of the second LED chip 52 is silver-plated, thereby preventing the light emitted by the first LED chip 51 from passing through the second LED chip 52 to excite the second phosphor layer 22, and preventing the light emitted by the second LED chip 52 from passing through the first LED chip 51 and being reflected by the reflective adhesive 3 or the substrate 1 to excite the first phosphor layer 21. This allows the first LED chip 51 and the second LED chip 52 to independently excite their respective phosphor layers, improving the reliability of light mixing. Furthermore, the silver plating enables reflection from both sides, preventing a reduction in luminous efficiency.

[0036] Example 2: Reference Figure 3 As shown, this embodiment provides a method for fabricating a multi-LED chip stacked light source packaging structure as described above, including the following steps: Step S1: Prepare a fluorescent film; The fluorescent film is prepared by coating fluorescent adhesive. In this embodiment, the thickness of the fluorescent film is 100 μm.

[0037] Step S2: Cut the fluorescent film to form a plurality of first phosphor layers 21, each first phosphor layer 21 having an opening corresponding to the size of each second LED chip 52; specifically, the fluorescent film is coated onto a cutting film, the surface adhesion of the cutting film being 20-200gf / 25mm; the fluorescent film is laser-cut, and the opening portion corresponding to the size of each second LED chip 52 is eliminated by laser in a diagonal manner; the fluorescent film is physically cut to form the first phosphor layers 21, so that each first phosphor layer 21 has the number of openings of the second LED chip 52 in each packaging structure.

[0038] Step S3: Fix the first LED chip 51 to the upper side of the substrate 1, apply the transparent adhesive 4 to the upper side of the first LED chip 51 and fix the first phosphor layer 21, and squeeze the first phosphor layer 21 so that the transparent adhesive 4 surrounds the first LED chip 51. Specifically, fix the first LED chip 51 to the upper side of the substrate 1 by flux reflow soldering eutectic technology or a eutectic machine, apply the transparent adhesive 4 to the upper side of the first LED chip 51, press the first phosphor layer 21 onto the transparent adhesive 4, so that the transparent adhesive 4 wraps around the side of the first LED chip 51 and forms a downward-sloping surface. The transparent adhesive 4 is transparent silicone.

[0039] Step S4: Fix the second LED chip 52 in the opening of the first phosphor layer 21 on the upper side of the first LED chip 51; specifically, it also includes wire bonding, using the gold wire 6 to connect the top electrode of the second LED chip 52 and the corresponding electrode on the upper side of the substrate 1.

[0040] Step S5: Fix the reflective adhesive 3 on the upper side of the substrate 1. The reflective adhesive 3 surrounds the first LED chip 51. The reflective adhesive 3 is white adhesive, and the inner and outer sides of the reflective adhesive 3 form inclined surfaces, with the upper side connected to the first phosphor layer 21.

[0041] Step S6: Cover the upper side of the first phosphor layer 21 and the upper side of the second LED chip 52 with a second phosphor layer 22; specifically, a pre-prepared diluted mixture of phosphor and silicone is sprayed by a powder spraying device to form the second phosphor layer 22, which covers the upper side of the second LED chip 52, the upper side of the first phosphor layer 21, the outer side of the reflective adhesive 3, and the upper side of the substrate 1 that is covered.

[0042] Step S7: Cut the substrate 1 to form a single light source package structure. Before cutting the substrate 1, a molding process is also included to mold a lens 7 on the substrate 1. The lens 7 surrounds the first LED chip 51, the second LED chip 52, the reflective adhesive 3, the transparent adhesive 4, and the phosphor layer.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A light source packaging structure with multiple stacked LED chips, characterized in that, It includes a substrate (1), a phosphor layer, a reflective adhesive (3), a transparent adhesive (4), a first LED chip (51), and multiple second LED chips (52). Multiple pads are provided on the upper side of the substrate (1); The first LED chip (51) is fixed on the upper side of the substrate (1), and the electrodes of the first LED chip (51) are electrically connected to the pads; Multiple second LED chips (52) are fixed on the upper side of the first LED chip (51), and the electrodes of the first LED chip (51) are electrically connected to the pads; The reflective adhesive (3) is fixed to the upper side of the substrate (1), surrounds the first LED chip (51) around its perimeter, and is inclined on the inner side to form a pit. The phosphor layer includes a first phosphor layer (21) and a second phosphor layer (22); the first phosphor layer (21) and the second LED chip (52) cover the upper side of the first LED chip (51), and the first phosphor layer (21) covers the upper side of the reflective adhesive (3); the second phosphor layer (22) covers the upper side of the first phosphor layer (21) and the second LED chip (52), and the second phosphor layer (22) surrounds the first LED chip (51) on all sides; The transparent adhesive (4) fills the cavity formed by the first LED chip (51), the inner side of the reflective adhesive (3), and the first phosphor layer (21).

2. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The first LED chip (51) is a flip-chip LED chip.

3. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The second LED chip (52) is a standard LED chip.

4. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The electrode on the upper side of the second LED chip (52) is electrically connected to the pad on the upper side of the substrate (1) via a gold wire (6).

5. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The first LED chip (51) and a plurality of second LED chips (52) are electrically connected to a plurality of different pads.

6. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The reflective adhesive (3) is inclined on the outside, and the inclined surface is inclined upward.

7. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The phosphor layer covers the outer side of the reflective adhesive (3) and extends to the upper side of the substrate (1).

8. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, The first LED chip (51) and the second LED chip (52) have different emission color temperature values, and the emission color values ​​of multiple second LED chips (52) are different.

9. The light source packaging structure of multi-LED chip stacking according to claim 1, characterized in that, It also includes a lens (7), which is fixed to the upper side of the substrate (1) and surrounds the first LED chip (51), the second LED chip (52), the reflective adhesive (3), the transparent adhesive (4) and the phosphor layer.

10. The method for fabricating a multi-LED chip stacked light source packaging structure as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: Prepare a fluorescent film; Step S2: Cut the fluorescent film to form a plurality of first phosphor layers (21), and form an opening in each first phosphor layer (21) corresponding to the size of each second LED chip (52); Step S3: Fix the first LED chip (51) on the upper side of the substrate (1), set the transparent adhesive (4) on the upper side of the first LED chip (51) and fix the first phosphor layer (21), squeeze the first phosphor layer (21) so that the transparent adhesive (4) surrounds the first LED chip (51); Step S4: Fix the second LED chip (52) in the opening of the first phosphor layer (21) on the upper side of the first LED chip (51). Step S5: Fix the reflective adhesive (3) on the upper side of the substrate (1), and the reflective adhesive (3) surrounds the first LED chip (51); Step S6: Cover the upper side of the first phosphor layer (21) and the upper side of the second LED chip (52) with a second phosphor layer (22); Step S7: Cut the substrate (1) to form a single light source packaging structure.

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