Transfer film and its application

Abstract

The present invention provides a transfer film and its application, wherein the transfer film can be used for mass transfer of Mini LED and / or Micro LED. The transfer film of the present invention comprises a substrate and an acrylic adhesive layer and a debonding adhesive layer arranged on both sides of the substrate, and the debonding adhesive layer is used to bond with Mini LED and / or Micro LED. The transfer film of the present invention uses a debonding adhesive layer to achieve reversible adhesion to Mini LED and / or Micro LED, and the debonding adhesive layer can adhere to Mini LED and / or Micro LED with a size of less than 50 μm, which solves the problem that the vacuum suction device in the traditional process cannot effectively adsorb Mini LED and / or Micro LED with a size of less than 50 μm. At the same time, it is simple to use and low in cost, and does not require the addition of complex processes or expensive instruments. The debonding adhesive layer can be firmly adsorbed with Mini LED and / or Micro LED under normal conditions, but after the debonding treatment, the bonding force between the debonding adhesive layer and Mini LED and / or Micro LED is significantly reduced, so that the transfer film can be detached from Mini LED and / or Micro LED without taking away Mini LED and / or Micro LED.

Description

Technical Field

[0001] The present invention relates to the field of film structures, and in particular to a film for mass transfer of Mini LED and / or Micro LED and applications thereof. Background Art

[0002] Light Emitting Diode (LED) is a solid-state semiconductor chip that converts electrical energy into light energy. It is composed of P-type semiconductor and N-type semiconductor, which form a PN junction. When current passes through the PN junction, electrons are converted into photons and released. It has high luminous efficiency, which can reach 80lm / w or higher, and a lifespan of up to 100,000 hours. The LCD screen will not turn yellow after long-term use. It uses solid-state packaging and has good impact resistance. It works without flickering when using direct current. After using quantum technology, the color gamut range is greatly enhanced, the size is small, and the thickness of electronic equipment is effectively reduced. Currently, televisions, monitors, and mobile phones all use LED backlights. At the same time, LEDs are also widely used in various indications, displays, decorations, general lighting, and city night scenes.

[0003] Mini LED and Micro LED are both further improvements on existing LEDs. Mini LED is used in displays for smartphones, TVs, car monitors, and gaming laptops, while Micro LED can be used in wearable phones, smartphones, and car monitors, augmented reality / virtual reality products, wall and TV monitors, etc. The most obvious difference between Mini LED and Micro LED relative to LED is the size of a single LED. The size of LED is about 3mm, while the size of Mini LED and Micro LED is basically below 50μm. Therefore, more Mini LED or Micro LED is needed to form a backlight source. Therefore, traditional LED processing technology is increasingly difficult to meet the processing needs of Mini LED and Micro LED.

[0004] In the processing technology of LED, Mini LED and Micro LED, the packaging process seriously affects the yield rate of the product. In the packaging process, the step of transferring the LED chip from the substrate to the driver circuit board affects the accuracy of the single chip, and ultimately affects the yield rate of the product. The number of LEDs transferred at a time is very large. This process is called mass transfer. The efficiency and yield rate of mass transfer determine the economic value of the product. Conventional LEDs use vacuum suction to transfer mass in the packaging process, but because the vacuum tube can only reach about 80μm under the physical limit, and the size of Mini LED or Micro LED is basically less than 50μm, the technology of using vacuum tubes for mass transfer is no longer applicable in the era of Mini LED and Micro LED. Therefore, the mass transfer process is a huge bottleneck restricting the development of Mini LED and Micro LED.

[0005] Many companies have proposed solutions to improve the mass transfer process, such as using a transfer head with a bipolar structure to adsorb and release LEDs through electrostatic force; using a print head with an elastic mold to print the LED to a specified location; mixing magnetic materials before Micro LED cutting to adsorb and release them through electromagnetic absorption; using laser and ultraviolet irradiation on the gallium nitride sheet at the junction of the LED and the substrate to produce gallium metal and nitrogen to separate the LED from the substrate. The above methods all have certain positive effects, but there are also certain defects, such as lack of accuracy, low efficiency, expensive equipment, and increased production processes and costs. Summary of the invention

[0006] Based on the above problems, the first aspect of the present invention provides a transfer film, which can be used for mass transfer of Mini LED and Micro LED. It has the characteristics of good precision, high efficiency, and no need to add additional equipment and increase production process and cost.

[0007] The transfer film of the present invention comprises a substrate and an acrylic adhesive layer and a viscosity-reducing adhesive layer arranged on both sides of the substrate, and the viscosity-reducing adhesive layer is used for bonding with Mini LED and / or Micro LED.

[0008] Compared with the prior art, the transfer film of the present invention uses a debonding adhesive layer to achieve reversible adhesion to Mini LED and / or Micro LED. The debonding adhesive layer can adhere to Mini LED and / or Micro LED with a size less than 50 μm, solving the problem that the vacuum suction device in the traditional process cannot effectively adsorb Mini LED and / or Micro LED with a size less than 50 μm. At the same time, it is simple to use and low cost, and does not require the addition of complex processes or expensive instruments to increase production costs and reduce yields. The debonding adhesive layer can be firmly adsorbed with Mini LED and / or Micro LED under normal conditions, but after the debonding treatment, the bonding force between the debonding adhesive layer and Mini LED and / or Micro LED is significantly reduced, so that the transfer film can be detached from the Mini LED and / or Micro LED without taking away the Mini LED and / or Micro LED. The transfer film of the present invention is used to transfer a large amount of Mini LED and / or Micro LED, and the transfer yield is 99.9999%, and the accuracy of each Mini LED and / or Micro LED is controlled within ±0.5 μm.

[0009] Furthermore, the thickness of the substrate is 15-35 μm, which may be but not limited to 15 μm, 18 μm, 20 μm, 24 μm, 28 μm, 31 μm, and 35 μm; the thickness of the acrylic adhesive layer is 50-150 μm, which may be but not limited to 50 μm, 80 μm, 100 μm, 120 μm, and 150 μm; the thickness of the viscosity-reducing adhesive layer is 25-75 μm, which may be but not limited to 25 μm, 35 μm, 45 μm, 55 μm, and 75 μm. The materials of the substrate, acrylic adhesive layer and anti-viscosity adhesive layer are all elastic polymer materials. The thickness of these three layers will affect their elasticity and rigidity. At the same time, the thickness of the acrylic adhesive layer and the anti-viscosity adhesive layer will affect their adhesion and the stability of the adhered objects. The substrate, acrylic adhesive layer and anti-viscosity adhesive layer of the transfer film of the present application have appropriate thicknesses. Therefore, the transfer film of the present application has good elasticity so that it can be curled but not overly soft, and at the same time can firmly and stably adhere to Mini LED and / or Micro LED.

[0010] Furthermore, the viscosity-reducing adhesive layer may be, but is not limited to, a UV viscosity-reducing adhesive whose adhesive force is significantly reduced after ultraviolet light irradiation. The ultraviolet light generating device is cheap and easy to obtain, has high safety, and can achieve a large range and uniform irradiation surface. Therefore, using UV viscosity-reducing adhesive as the viscosity-reducing adhesive layer does not require the addition of expensive equipment, and can achieve safe and efficient production.

[0011] Further, the adhesive force of the anti-viscosity adhesive layer under normal conditions is 1-50N / 25mm, which may be, but not limited to, 1N / 25mm, 5N / 25mm, 10N / 25mm, 15N / 25mm, 25N / 25mm, 30N / 25mm, 35N / 25mm, 40N / 25mm and 50N / 25mm; the adhesive force of the anti-viscosity adhesive layer after the anti-viscosity treatment is 0-0.1N / 25mm, which may be, but not limited to, 0.01N / 25mm, 0.03N / 25mm, 0.05N / 25mm, 0.07N / 25mm and 0.1N / 25mm. The anti-viscosity adhesive layer under normal conditions can firmly adhere to the Mini LED and / or Micro LED, and the anti-viscosity adhesive layer after the anti-viscosity treatment can easily detach from the Mini LED and / or Micro LED without causing the Mini LED and / or Micro LED to leave the driver circuit board or be out of position.

[0012] Furthermore, the adhesive force of the acrylic adhesive layer is 10-30N / 25mm, which may be, but is not limited to, 10N / 25mm, 15N / 25mm, 20N / 25mm, 25N / 25mm and 30N / 25mm. The acrylic adhesive layer can firmly bond the substrate, and its adhesive force is greater than the adhesive force of the adhesive layer after the adhesive reduction treatment, so the transfer film after the adhesive reduction treatment can be separated from the Mini LED and / or Micro LED by applying force to the acrylic adhesive layer.

[0013] Furthermore, the surfaces of the acrylic adhesive layer and the viscosity-reducing adhesive layer are respectively covered with release film layers. The release film layer can protect the acrylic adhesive layer and the viscosity-reducing adhesive layer, and facilitates the storage of the transfer film.

[0014] Furthermore, the release film layer is a PET release film, which has a low adhesive force when in contact with the acrylic adhesive layer and the viscosity-reducing adhesive layer, and can therefore be easily detached for use.

[0015] Furthermore, the transfer film can be rolled into a coil or unfolded and cut into sheets, which is beneficial to the storage of the transfer film. The materials thereof can all be flexible materials, including materials of the substrate, the viscosity-reducing adhesive layer and the acrylic adhesive layer.

[0016] A second aspect of the present invention provides an application of a transfer film, specifically, realizing mass transfer of Mini LED and / or Micro LED through the transfer film of the present application.

[0017] Compared with the prior art, the application of the transfer film of the present invention utilizes the characteristics of the transfer film's higher adhesion under normal conditions and significantly reduced adhesion after viscosity reduction to achieve reversible adhesion to Mini LED and / or Micro LED, solving the problem of poor adsorption effect of Mini LED and / or Micro LED in the vacuum adsorption step in the prior art.

[0018] Further, the application of the transfer film of the present invention can be carried out by the following steps in sequence:

[0019] S11: Cut the transfer film into sheets as required, and arrange the Mini LEDs and / or Micro LEDs on the substrate as required to obtain an LED assembly;

[0020] S12: bonding the transfer film to the LED assembly;

[0021] S13: Separating the transfer film bonded with the Mini LED and / or Micro LED from the substrate;

[0022] S14: transferring the transferred film to a driving circuit board, so that the Mini LED and / or Micro LED is attached to the driving circuit board to form an intermediate structure;

[0023] S15: performing a de-viscosity treatment on the intermediate structure so that the Mini LED and / or Micro LED is detached from the transfer film to achieve mass transfer of Micro LED and / or Mini LED.

[0024] The above steps use the transfer film of the present invention to achieve mass transfer of Mini LED and / or Micro LED, with good yield, high efficiency, simple equipment and steps, and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the transfer film of the present invention.

[0026] Figure 2 The figure is a schematic diagram of the application process of the transfer film of the present invention.

[0027] Component number description

[0028] 100-transfer film; 1-substrate; 2-reducing adhesive layer; 3-acrylic adhesive layer; 4-release film layer; 5-substrate; 6-LED assembly; 61-Mini LED and / or Micro LED; 7-driving circuit board; 8-intermediate structure DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be described more comprehensively with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings, but the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive, rather than to limit the scope of protection of the present invention.

[0030] like Figure 1 As shown, the transfer film 100 of the present invention includes a substrate 1, a UV anti-viscosity adhesive layer 2 and an acrylic adhesive layer 3 arranged on both sides of the substrate 1, and a release film layer 4 arranged outside the UV anti-viscosity adhesive layer 2 and the acrylic adhesive layer 3. In addition, the thickness of the substrate is 20μm, the thickness of the acrylic adhesive layer is 100μm, the thickness of the anti-viscosity adhesive layer is 50μm, and the adhesive force of the acrylic adhesive layer is 15N / 25mm. When the transfer film 100 is used, it is first cut into a suitable shape according to customer needs, so that it can meet the needs of different products. The UV anti-viscosity adhesive layer 2 can significantly reduce the adhesive force under the irradiation of ultraviolet light. Under normal conditions, the adhesive force of the UV anti-viscosity adhesive layer 2 is 10N / 25mm, and the adhesive force of the anti-viscosity adhesive layer 2 after the anti-viscosity treatment is 0.04N / mm. The UV anti-viscosity adhesive layer 2 has obvious advantages over laser curing adhesive. For example, the existing ultraviolet light generating equipment can easily obtain a large and uniform ultraviolet light emitting surface, so that a large range of UV anti-viscosity adhesive layer 2 can be uniformly treated for anti-viscosity. The laser generator has a smaller emitting surface, resulting in lower efficiency, and the cost and danger of the ultraviolet generator are significantly lower than the laser generator. Therefore, the use of the UV anti-viscosity adhesive layer 2 can achieve high-efficiency, high-yield, low-cost and low-risk mass transfer. There are two release film layers 4, which are respectively located on the outside of the anti-viscosity adhesive layer 2 and the acrylic adhesive layer 3. The release film layer 4 has a low bonding force when in contact with the anti-viscosity adhesive layer 2 or the acrylic adhesive layer 3, and a PET release film or the like can be used.

[0031] like Figure 2 As shown, the process S100 of the transfer film application method of the present invention comprises the following steps:

[0032] S11: Cut the transfer film 100 into sheets as required, and arrange the Mini LED and / or Micro LED 61 on the substrate 5 as required to obtain an LED assembly 6, with the end of the LED assembly 6 to be bonded to the transfer film 100 facing upward, and the end of the LED assembly 6 to be bonded to the driver circuit board 7 facing downward. As a method, a corresponding number of positioning grooves may be provided on the substrate 5, and each Mini LED and / or Micro LED 61 is positioned in the positioning groove to obtain an assembly 6;

[0033] S12: removing the release layer 4 on the transfer film 100 facing the LED assembly 6, and bonding the transfer film 100 to the LED assembly 6 from above the LED assembly 6 to prevent the Mini LED and / or Micro LED 61 in the LED assembly 6 from being displaced;

[0034] S13: Separate the transfer film 100 bonded with the Mini LED and / or Micro LED 61 from the substrate 5, and check whether the Mini LED and / or Micro LED 61 is fully adhered;

[0035] S14: moving the transfer film 100 bonded with the Mini LED and / or Micro LED 61 to the top of the driving circuit board 7, aligning each Mini LED and / or Micro LED 61 with the circuit on the driving circuit board 7, and then laminating the Mini LED and / or Micro LED 61 with the driving circuit board 7 to form an intermediate structure 8. Usually, the lamination of the Mini LED and / or Micro LED 61 with the driving circuit board 7 is achieved by welding;

[0036] S15: Perform a viscosity reduction treatment on the intermediate structure 8, that is, perform a viscosity reduction treatment on the UV viscosity reduction adhesive layer 2 on the transfer film 100, so that the Mini LED and / or Micro LED 61 is separated from the transfer film 100 to achieve a mass transfer of the Mini LED and / or Micro LED 61, and finally check whether there are Mini LEDs and / or Micro LEDs 61 that are not attached to the driving circuit board 7. After the UV viscosity reduction adhesive layer 2 on the transfer film 100 is subjected to a viscosity reduction treatment, the transfer film 100 can be separated from the Mini LED and / or Micro LED 61, or the Mini LED and / or Micro LED 61 and the transfer film 100 can be separated by adsorption, adhesion, etc.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. Transfer film, used for mass transfer of Mini LED and / or Micro LED, characterized in that: It comprises a substrate and an acrylic adhesive layer and a debonding adhesive layer arranged on both sides of the substrate, the debonding adhesive layer is used to bond with the Mini LED and / or the MicroLED, the material of the debonding adhesive layer is UV debonding adhesive, the adhesive force of the debonding adhesive layer is 1-50N / 25mm under normal conditions, the adhesive force of the debonding adhesive layer after debonding treatment is 0-0.1N / 25mm, the debonding treatment is carried out under ultraviolet light, and the adhesive force of the acrylic adhesive layer is 10-30N / 25mm.

2. The transfer film according to claim 1, characterized in that The thickness of the substrate is 15-35 μm, the thickness of the acrylic adhesive layer is 50-150 μm, and the thickness of the viscosity-reducing adhesive layer is 25-75 μm.

3. The transfer film according to claim 1, characterized in that The surfaces of the acrylic adhesive layer and the viscosity-reducing adhesive layer are respectively covered with release film layers.

4. The transfer film according to claim 3, characterized in that The release film layer is a PET release film.

5. The transfer film according to claim 1, characterized in that It can be rolled into a roll or unrolled and cut into sheets.

6. An application of a transfer film, characterized in that: Use the transfer film described in any one of claims 1-5 to achieve mass transfer of the Mini LED and / or the Micro LED.

7. The use of the transfer film according to claim 6, characterized in that: It includes the following steps in sequence: S11: Cutting the transfer film into sheets as required, and arranging the Mini LEDs and / or the Micro LEDs on a substrate as required to obtain an LED assembly; S12: bonding the transfer film to the LED assembly; S13: Separating the transfer film bonded with the Mini LED and / or the Micro LED from the substrate; S14: transferring the transfer film to a driving circuit board, so that the Mini LED and / or the Micro LED is attached to the driving circuit board to form an intermediate structure; S15: performing a de-viscosity treatment on the intermediate structure so that the Mini LED and / or the Micro LED are detached from the transfer film to achieve mass transfer of the Micro LED and / or the Mini LED.

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