A method for fabricating a fan-out LED device package by film stretching combined with laser assistance

Abstract

The application discloses a fan-out LED device packaging method prepared by film stretching combined with laser assistance, and the packaging method comprises the following steps: providing a stretchable film with LED chips pasted thereon; stretching the stretchable film; transferring the LED chips to a temporary carrier; packaging the LED chips; identifying the electrode position of the LED chips by using a detection system; generating a circuit pattern, a device contour, an optimal cutting path and a defective device mark by a computer; uniformly forming a photoresist layer on the electrode surface; performing photoetching by using a laser to form a circuit photoetching channel; filling the circuit photoetching channel with conductive material to form a circuit; forming a protective layer on the circuit and exposing part of the circuit as a solder pad to realize electrical lead-out of the circuit. The application adopts the fan-out packaging technology, realizes redistribution of the LED chips by using the stretchable film, and precisely prepares the circuit by using the laser, so that the packaging method has the advantages of high packaging efficiency, good quality, low cost and high reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication. Background Technology

[0002] The LED was first invented in 1907. It is a special semiconductor that emits light when an electric current passes through it. Due to its advantages such as long lifespan, high luminous efficacy, good color rendering, energy saving and environmental friendliness, and short response time, LEDs have rapidly replaced traditional light sources in recent decades and are widely used in fields such as indication, display, lighting, and decoration, which has greatly improved people's lives.

[0003] Fan-out packaging technology first appeared in the IC industry in 2006. Its market size subsequently grew significantly, gradually gaining attention from engineers in the LED packaging field. Fan-out packaging technology increases the packaging area of ​​individual devices by redistributing the chip, followed by the fabrication of circuitry and pads, and finally, dicing to obtain individual devices. As an advanced packaging method, fan-out packaging eliminates the need for a substrate and frame, as well as wire bonding. Therefore, it not only improves packaging efficiency and reduces costs, but also offers advantages such as high integration, small size, low power consumption, and good electrical and thermal performance. However, traditional fan-out packaging requires a mask and demands high chip transfer precision, resulting in high cost, low efficiency, and low yield.

[0004] With the development of technology and the expansion of application fields, the packaging methods of LED devices have also undergone tremendous changes. Existing LED packaging methods include Lamp, SMD, COB, CSP, etc., but with the increasing demand for portable electronic products, people have also put forward higher requirements for their performance, size, cost, etc., so there is an urgent need to develop an advanced packaging technology to meet market demands. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the aforementioned technical problems in the prior art. Therefore, embodiments of the present invention provide a method for packaging fan-out LED devices using film stretching combined with laser-assisted fabrication, to address the problems of low LED packaging efficiency, high cost, low precision, poor heat dissipation, large size, and low yield in related technologies.

[0006] The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to an embodiment of the present invention is characterized by comprising the following steps:

[0007] S1: A stretchable film is provided, on which LED chips are attached;

[0008] S2: Stretch the stretchable film along at least one direction to increase the distance between adjacent LED chips, wherein the distance between the LED chips is greater in a specified direction than in other directions;

[0009] S3: Transfer the LED chip from the stretchable film to the first surface of the temporary carrier plate, the first surface of the temporary carrier plate being pre-coated with a temporary adhesive layer;

[0010] S4: The LED chip is encapsulated using encapsulation material to form at least one encapsulation layer;

[0011] S5: The detection system is used to accurately identify the electrode positions of the LED chip, and the computer generates circuit diagrams, device outlines, optimal cutting paths, and defective device location markers.

[0012] S6: A layer of photoresist is uniformly formed on the surface of the electrode and the encapsulation layer. The computer-controlled laser lithography equipment is used to perform photolithography on the photoresist surface, thereby exposing the electrode and forming a line photolithography track.

[0013] S7: The conductive material is used to fill the photolithographic traces of the circuit, and then the surface is cleaned to form the circuit.

[0014] S8: A protective layer is formed on the circuit and the encapsulation layer, and a portion of the circuit is exposed in the middle of the protective layer to serve as a solder pad, thereby realizing the electrical lead-out of the circuit;

[0015] S9: Cut the packaged LED chip according to the optimal cutting path mark to obtain an independent LED device, then remove the marked defective devices, and test and sort the independent LED devices. The independent LED device contains at least one LED chip.

[0016] In an optional or preferred embodiment, in step S1, the type of the LED chip is one or more of the following: upright chip, flip chip, and vertical chip.

[0017] In an optional or preferred embodiment, in step S2, the stretchable film is stretched and transferred multiple times to achieve a preset spacing between the LED chips.

[0018] In optional or preferred embodiments, in step S3, the material of the temporary carrier plate is one of glass, metal, semiconductor, polymer, and ceramic; and the temporary adhesive layer is one of thermally degradable adhesive and photodegradable adhesive.

[0019] In an optional or preferred embodiment, in step S4, the encapsulation material is one or more of epoxy resin, silicone resin, polyimide, and ceramic.

[0020] In an optional or preferred embodiment, in step S4, the encapsulation material includes one or more functional particles with reflection, absorption, and conversion functions. The functional particles are one of titanium dioxide, zinc oxide, silicon dioxide, barium sulfate, aluminum oxide, zirconium dioxide, graphite, phosphor, metal particles, quantum dots, and perovskite.

[0021] In optional or preferred embodiments, in step S4, the encapsulation method for forming the encapsulation layer is one or more of compression molding, injection molding, liquid encapsulation, lamination, printing, and spin coating.

[0022] In optional or preferred embodiments, in step S7, the conductive material includes metallic and / or non-metallic materials. In this technical solution, the metallic material can be gold, silver, copper, aluminum, iron, nickel, platinum, tin, or their alloys. The non-metallic material can be a semiconductor material, a conductive polymer material, a carbon material, or a metal oxide material; the semiconductor material can be silicon or germanium; the conductive polymer material can be polyacetylene, polyaniline, polypyrrole, or polystyrene; the carbon material can be graphene, carbon nanotubes, or graphite; and the metal oxide material can be zinc oxide or indium gallium oxide.

[0023] In optional or preferred embodiments, the method for forming the circuit in step S7 includes one or more of the following processes: vapor deposition, sputtering, electroplating, electroless plating, and printing.

[0024] In an optional or preferred embodiment, in step S8, the pads are thickened to facilitate electrical connection with the outside world.

[0025] Based on the above technical solutions, the embodiments of the present invention have at least the following beneficial effects: The above technical solutions redistribute LED chips by using film stretching, eliminating the need for a cumbersome transfer process, reducing the precision requirements of fan-out packaging equipment, and ensuring high reliability; the laser has high precision and speed, and with the help of image recognition and computers, it is easy to achieve digital and intelligent production; no custom mask is required, saving costs and improving yield. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0027] Figure 1 This is a schematic diagram of the structure presented in step S1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure presented in step S2 of the present invention;

[0029] Figure 3This is a schematic diagram of the structure presented in step S3 of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure presented in step S4 of the present invention;

[0031] Figure 5 This is a schematic diagram of the structure presented in step S6 of the present invention;

[0032] Figure 6 and Figure 7 This is a schematic diagram of the structure presented in step S7 of the present invention;

[0033] Figure 8 This is a schematic diagram of the structure presented in step S8 of the present invention;

[0034] Figure 9 This is a schematic diagram of the structure after the pads are thickened in an embodiment of the present invention;

[0035] Figure 10 This is a bottom view of the LED chip after packaging in an embodiment of the present invention;

[0036] Figure 11 This is a schematic diagram of the structure presented in step S9 of the present invention.

[0037] Reference numerals: Stretchable film 100, LED chip 101, electrode 102, temporary carrier 200, temporary adhesive layer 201, encapsulation layer 300, first encapsulation layer 301, second encapsulation layer 302, photoresist 400, lithography track 401, conductive material 402, circuit 403, protective layer 404, solder pad 405, independent LED device 406. Detailed Implementation

[0038] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limiting this invention.

[0040] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0041] In the description of this invention, unless otherwise explicitly defined, terms such as "setting," "installing," and "connecting" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0042] Reference Figures 1 to 11 A method for packaging fan-out LED devices using film stretching combined with laser-assisted fabrication is presented, comprising the following steps:

[0043] S1, refer to Figure 1 A stretchable film 100 is provided, on which an LED chip 101 is attached.

[0044] The LED chip 101 can be one or more of the following types: upright chip, flip chip, and vertical chip. In this embodiment, all LED chips 101 are flip chips. The wavelengths of the light emitted by the LED chips 101 can be the same or different. In this embodiment, there are three types of LED chips 101: a red light chip with a wavelength of 625nm, a green light chip with a wavelength of 525nm, and a blue light chip with a wavelength of 470nm.

[0045] S2, refer to Figure 2 The stretchable film 100 is stretched along at least one direction to increase the distance between adjacent LED chips 101. The distance between LED chips 101 is greater in a specified direction than in other directions.

[0046] The LED chips 101 can be spaced at a preset distance by repeatedly stretching and transferring the stretchable film 100.

[0047] In a specific direction, the distance between the LED chips 101 is greater than in other directions. This is to reserve space for the fabrication of the fan-out line 403 and the pad 405 in subsequent steps.

[0048] S3, refer to Figure 3 The LED chip 101 is transferred from the stretchable film 100 to the first surface of the temporary carrier 200, the first surface of which is pre-coated with a temporary adhesive layer 201.

[0049] The temporary carrier 200 is made of one of the following materials: glass, metal, semiconductor, polymer, or ceramic. In this embodiment, the temporary carrier 200 is made of glass because glass carriers are low in cost and have a relatively flat surface.

[0050] The temporary adhesive layer 201 is one of heat-loosening adhesive and light-loosening adhesive. In this embodiment, the temporary adhesive layer 201 is a light-loosening adhesive. By irradiating the temporary adhesive layer 201 with light of a specific wavelength, its adhesiveness can be lost. This method is simple, fast, and avoids direct contact.

[0051] S4, see reference Figure 4 The LED chip 101 is encapsulated using encapsulation materials to form at least one encapsulation layer 300.

[0052] The encapsulation material is one or more of epoxy resin, silicone resin, polyimide, and ceramic. In this embodiment, the encapsulation material is epoxy resin.

[0053] The encapsulation material includes one or more functional particles with reflective, absorbent, and conversion functions. These functional particles are selected from one of the following: titanium dioxide, zinc oxide, silicon dioxide, barium sulfate, aluminum oxide, zirconium dioxide, graphite, phosphor, metal particles, quantum dots, and perovskite. The above-mentioned functional particles are preferred embodiments and should not be construed as limiting the scope of protection of this invention. Those skilled in the art can use other functional particles, and the principle of equivalents applies; these should be considered to be included within the scope of protection of this invention. In this embodiment, the functional particle is titanium dioxide, meaning the encapsulation material uses titanium dioxide.

[0054] The encapsulation layer 300 can be a single layer or multiple layers. In this embodiment, the encapsulation layer 300 has a dual-layer structure, consisting of a first encapsulation layer 301 and a second encapsulation layer 302.

[0055] The encapsulation method for forming the encapsulation layer 300 is one or more of compression molding, injection molding, liquid encapsulation, lamination, printing, and spin coating. In this embodiment, the encapsulation method is lamination.

[0056] Separate the encapsulation layer 300 and the LED chip 101 from the temporary carrier board 200.

[0057] S5, the detection system is used to accurately identify the position of the electrode 102 of the LED chip 101, and the computer generates circuit diagrams, device outlines, optimal cutting paths and defective device location marks.

[0058] In some embodiments, the electrode 102 may be located on the same side of the LED chip 101 or on both sides thereof. If the electrode 102 is located on both sides of the LED chip 101, it is necessary to guide the electrode 102 to the same side in advance using methods such as laser drilling or wire drawing before proceeding with subsequent steps. In this embodiment, the electrode 102 is located on the same side of the LED chip 101.

[0059] S6, see reference Figure 5 A layer of photoresist 400 is uniformly formed on the surface of electrode 102 and encapsulation layer 300. A computer-controlled laser lithography device is used to perform photolithography on the surface of photoresist 400, thereby exposing electrode 102 and forming line photolithography track 401.

[0060] The photoresist 400 can be either a positive or negative photoresist. In this embodiment, the photoresist 400 is a positive photoresist.

[0061] S7, see reference Figure 6 Conductive material 402 is used to fill the photolithography path 401 of the circuit; refer to Figure 7 Then the surface is cleaned to form circuit 403.

[0062] The conductive material 402 is a metallic material or other conductive material. The conductive material 402 includes metallic and / or non-metallic materials. Metallic materials may be gold, silver, copper, aluminum, iron, nickel, platinum, tin, and their alloys. Non-metallic materials may be semiconductor materials, conductive polymer materials, carbon materials, or metal oxide materials; semiconductor materials may be silicon or germanium; conductive polymer materials may be polyacetylene, polyaniline, polypyrrole, or polystyrene; carbon materials may be graphene, carbon nanotubes, or graphite; and metal oxide materials may be zinc oxide or indium gallium oxide. In this embodiment, the conductive material 402 is copper.

[0063] The method for forming line 403 includes one or more of the following: vapor deposition, sputtering, electroplating, electroless plating, and printing. In this embodiment, sputtering is used to form line 403 because sputtered lines have a better quality.

[0064] In steps S6 and S7, photoresist is used followed by laser lithography, and then conductive material is used to fill and form the circuit. In some other embodiments, photoresist may not be required. After steps S1-S5, a layer of metal is first deposited on the electrode surface, and then a laser is used to melt the metal to form the circuit. This method does not require photoresist. In some other embodiments, laser may not be required. After steps S1-S5, a layer of photoresist is first spin-coated on the electrode surface, and then DMD technology is used to directly expose the circuit pattern to prepare the circuit. This type of circuit preparation method should also be considered an equivalent method of circuit etching in this invention.

[0065] S8, refer to Figure 8 A protective layer 404 is formed on the circuit 403 and the encapsulation layer 300, and a portion of the circuit is exposed in the middle of the protective layer 404 to serve as a pad 405, thereby realizing the electrical lead-out of the circuit 403.

[0066] In other preferred embodiments, refer to Figure 9 The 405 pad is thickened to facilitate electrical connection with the external environment. This is understandable. Figure 8 The pad 405 shown can be used as an electrical connection point. Figure 9 The pad 405 shown is another embodiment, which can be thickened to facilitate electrical connection with the outside world. The thickening can be achieved through one or more of the following processes: vapor deposition, sputtering, electroplating, electroless plating, and printing.

[0067] Line 403 can be a single layer or multiple layers. In this embodiment, line 403 is a single layer.

[0068] like Figure 10 As shown, this is a bottom view of the LED chip 101 after packaging. Due to the unevenness of the stretchable film 100 when it is stretched, the position of the LED chip 101 is also randomly distributed. If the traditional mask exposure method is still used to prepare the circuit 403, the yield will be greatly reduced. However, the laser-assisted method can improve both the processing accuracy and processing speed at the same time.

[0069] S9, see reference Figure 11 The packaged LED chips are cut according to the optimal cutting path marking to obtain individual LED devices. Then, the marked defective devices are rejected, and the individual LED devices are tested and sorted. Each individual LED device contains at least one LED chip.

[0070] In this embodiment, each independent LED device 406 includes one LED chip each of red, green and blue colors to achieve full-color illumination.

[0071] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for packaging fan-out LED devices using film stretching combined with laser-assisted fabrication, characterized in that, Includes the following steps: S1, a stretchable film is provided, on which LED chips are attached; S2, stretch the stretchable film along at least one direction to increase the distance between adjacent LED chips, wherein the distance between the LED chips is greater in a specified direction than in other directions; S3, the LED chip is transferred from the stretchable film to the first surface of the temporary carrier plate, the first surface of the temporary carrier plate being pre-coated with a temporary adhesive layer; S4, The LED chip is encapsulated using encapsulation material to form at least one encapsulation layer; S5, The detection system is used to accurately identify the electrode positions of the LED chip, and the computer generates circuit diagrams, device outlines, optimal cutting paths and defective device location marks; S6, a layer of photoresist is uniformly formed on the surface of the electrode and the encapsulation layer, and the computer-controlled laser lithography equipment is used to perform photolithography on the surface of the photoresist, thereby exposing the electrode and forming a line photolithography track; S7, The conductive material is used to fill the photolithographic traces of the circuit, and then the surface is cleaned to form the circuit; S8, a protective layer is formed on the circuit and the encapsulation layer, and a portion of the circuit is exposed in the middle of the protective layer to serve as a solder pad, thereby realizing the electrical lead-out of the circuit; S9. The packaged LED chip is cut according to the optimal cutting path mark to obtain an independent LED device. Then, the marked defective devices are removed, and the independent LED devices are tested and sorted. The independent LED device contains at least one LED chip.

2. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S1, the type of LED chip is one or more of the following: upright chip, flip chip, and vertical chip.

3. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S2, the stretchable film is stretched and transferred multiple times to achieve a preset spacing between the LED chips.

4. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S3, the temporary carrier plate is made of one of glass, metal, semiconductor, polymer, or ceramic; and the temporary adhesive layer is one of thermally degradable adhesive or optically degradable adhesive.

5. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S4, the encapsulation material is one or more of epoxy resin, silicone resin, polyimide, and ceramic.

6. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S4, the encapsulation material includes one or more functional particles with reflection, absorption, and conversion functions. The functional particles are one of titanium dioxide, zinc oxide, silicon dioxide, barium sulfate, aluminum oxide, zirconium dioxide, graphite, phosphor, metal particles, quantum dots, and perovskite.

7. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S4, the encapsulation method for forming the encapsulation layer is one or more of compression molding, injection molding, liquid encapsulation, lamination, printing, and spin coating.

8. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S7, the conductive material includes metallic materials and / or non-metallic materials.

9. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S7, the method for forming the circuit includes one or more of the following processes: vapor deposition, sputtering, electroplating, electroless plating, and printing.

10. The packaging method for fan-out LED devices prepared by film stretching combined with laser-assisted fabrication according to claim 1, characterized in that: In step S8, the pads are thickened to facilitate electrical connection with the outside world.

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