Fluorescent diaphragm and preparation method thereof, and light-emitting device and packaging method thereof

Abstract

The invention provides a fluorescent diaphragm and a preparation method thereof, and a light-emitting device and a packaging method thereof, and the fluorescent diaphragm comprises a fluorescent glue layer which is provided with a first upper surface and a first lower surface, the fluorescent glue layer is formed on the surface of a light-emitting surface of a blue light LED chip, and the first lower surface is configured to be close to the light-emitting surface; the fluorescent glue layer emits white light under the excitation of the blue light LED chip; the functional adhesive layer is provided with a second upper surface and a second lower surface, the functional adhesive layer is formed on the surface of the fluorescent adhesive layer, and the fluorescent adhesive layer on the second lower surface is arranged close to the first upper surface of the fluorescent adhesive layer; and the surface roughness of the second upper surface of the functional adhesive layer is smaller than that of the first lower surface of the fluorescent adhesive layer. By changing the preparation sequence of the film layers, the surface of the functional adhesive layer is directly formed on the supporting film in the preparation process of the fluorescent film, the surface roughness of the surface is reduced, the adsorption force between a suction nozzle and the surface of the functional adhesive layer in the fluorescent film during subsequent packaging is increased, and the functional adhesive layer is smoothly transferred to the surface of an LED chip for packaging.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a fluorescent film and a preparation method thereof, a light-emitting device and a packaging method thereof. Background Art

[0002] When encapsulating LED chips, the commonly used method in the related art is to use a negative pressure nozzle to suck up the fluorescent film that has been cured and cut into appropriate sizes and transfer it to the corresponding LED chip surface. In some applications, since a single layer of fluorescent film cannot fully meet the luminous performance requirements of the product, a functional glue layer needs to be further formed on the surface of the original fluorescent glue layer to achieve the purpose of reducing blue light power and increasing luminous brightness.

[0003] For double-layer fluorescent film, the fluorescent adhesive layer usually needs to contact the light-emitting surface of the LED chip to be packaged. Therefore, during the packaging process, the suction nozzle contacts the surface of the functional adhesive layer in the fluorescent film. The process of the suction nozzle sucking the fluorescent adhesive layer is as follows: the double-layer fluorescent film to be packaged is placed on the surface of the peeling film with the functional adhesive layer surface facing up; the suction nozzle contacts the surface of the functional adhesive layer from above, and the vacuum pump starts to extract the air in the suction nozzle to form a negative pressure. The external atmospheric pressure will apply pressure to the suction nozzle to generate adsorption force on the fluorescent film. After many experiments and analyses, the R&D personnel found that: for the double-layer fluorescent film obtained by the traditional preparation process of preparing the fluorescent adhesive layer first and then the functional adhesive layer, there will be a problem that after one side of the fluorescent film is bonded to the surface of the peeling film, the fluorescent adhesive layer cannot be separated from the surface of the peeling film by adsorbing it by the suction nozzle, resulting in the inability to be used for LED chip packaging. Summary of the invention

[0004] In order to overcome the above shortcomings, the present invention provides a fluorescent film and a preparation method thereof, a light-emitting device and a packaging method thereof, so that the surface roughness of the second upper surface of the functional adhesive layer of the double-layer fluorescent film is smaller than the surface roughness of the first lower surface of the fluorescent adhesive layer, which is conducive to adsorption by a negative pressure suction nozzle and can be normally applied to the surface of the LED chip for packaging.

[0005] On the one hand, the present invention provides a fluorescent film, including: a fluorescent glue layer, having a first upper surface and a first lower surface, the fluorescent glue layer is formed on the light-emitting surface of a blue light LED chip, and the first lower surface is arranged close to the light-emitting surface; the fluorescent glue layer emits white light under the excitation of the blue light LED chip; a functional glue layer, having a second upper surface and a second lower surface, the functional glue layer is formed on the surface of the fluorescent glue layer, and the second lower surface fluorescent glue layer is arranged close to the first upper surface of the fluorescent glue layer; the surface roughness of the second upper surface of the functional glue layer is less than the surface roughness of the first lower surface of the fluorescent glue layer.

[0006] On the other hand, the present invention provides a light-emitting device, comprising: a blue light LED chip, the blue light LED chip having a light-emitting top, a light-emitting side and an electrode side opposite to the light-emitting top; a fluorescent film as mentioned above, wherein the first lower surface of the fluorescent glue layer in the fluorescent film is mounted close to the light-emitting top of the blue light LED chip.

[0007] In another aspect, the present invention provides a method for preparing a fluorescent film, comprising the following steps: A functional adhesive layer of a first thickness is formed on the surface of the support film by scraping glue, and baked into a semi-cured state; the functional adhesive layer has a second upper surface and a second lower surface, and the second upper surface is a side surface close to the support film; The fluorescent powder and the silica gel are uniformly mixed, and a fluorescent glue layer of a second thickness is further formed on the surface of the functional glue layer by scraping glue, and baked to a completely solidified state; the fluorescent glue layer has a first upper surface and a first lower surface, and the first upper surface is a side surface close to the functional glue layer; the fluorescent glue layer emits white light under the excitation of the blue light LED chip; The surface roughness of the second upper surface of the functional adhesive layer is smaller than the surface roughness of the first lower surface of the fluorescent adhesive layer.

[0008] In another aspect, the present invention provides a method for preparing a light-emitting device, comprising the following steps: The whole fluorescent film obtained by the above preparation method is transferred to the surface of the first peeling film and cut, the first lower surface of the fluorescent adhesive layer is adhered to the surface of the first peeling film, and the second upper surface of the functional adhesive layer is away from the first peeling film; The entire fluorescent film sheet after cutting is transferred to the surface of the blue film for film expansion operation, the second upper surface of the functional adhesive layer is adhered to the surface of the blue film, and the first lower surface of the fluorescent adhesive layer is away from the blue film; Transferring the entire fluorescent film sheet after film expansion to the surface of the second peeling film, wherein the first lower surface of the fluorescent adhesive layer adheres to the surface of the first peeling film, and the second upper surface of the functional adhesive layer is away from the second peeling film; The cut fluorescent adhesive layer is transferred and mounted on the light-emitting surface of the blue LED chip by adsorbing the second upper surface of the functional adhesive layer with a suction nozzle; the first lower surface of the fluorescent adhesive layer is arranged close to the light-emitting surface.

[0009] For the double-layer fluorescent film, under the normal preparation process, the surface roughness of the fluorescent film in contact with the suction nozzle is greater than the roughness of the surface in contact with the stripping film at the bottom, which makes it easy for the fluorescent film to form a strong adhesion with the stripping film at the bottom, while the adsorption force formed with the suction nozzle is smaller. The adsorption force formed by the suction nozzle on the fluorescent film is less than the sum of the adhesion between the film layer of the fluorescent film in contact with the stripping film and the gravity of the fluorescent film itself, which is insufficient to remove the fluorescent film from the surface of the stripping film. Therefore, the present invention prepares the functional adhesive layer first and then prepares the fluorescent adhesive layer on the surface thereof, so that the surface of the functional adhesive layer is directly formed on the supporting film during the preparation of the fluorescent film, which is beneficial to reducing the surface roughness of the surface, forming a smooth and flat surface, and increasing the adsorption force between the suction nozzle and the surface of the functional adhesive layer in the fluorescent film during subsequent packaging, so as to smoothly transfer it to the surface of the LED chip for packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the structure of a fluorescent film in one embodiment of the present invention; Figure 2 It is a schematic diagram of a structure for forming a functional adhesive layer in one embodiment of the present invention; Figure 3 It is a schematic diagram of a structure for forming a fluorescent glue layer in one embodiment of the present invention; Figure 4 A schematic diagram of the structure of cutting a fluorescent film sheet in one embodiment of the present invention; Figure 5 It is a structural schematic diagram of expanding a fluorescent film in one embodiment of the present invention; Figure 6 It is a schematic diagram of the structure of using a suction nozzle to suck up a fluorescent film in one embodiment of the present invention.

[0011] Reference numerals: 10-fluorescent film, 11-fluorescent adhesive layer, 111-first upper surface, 112-first lower surface, 12-functional adhesive layer, 121-second upper surface, 122-second lower surface, 20-support film, 30-first peeling film, 40-blue film, 50-second peeling film, 60-nozzle. DETAILED DESCRIPTION

[0012] In order to more clearly illustrate the implementation cases of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings and other implementation methods can be obtained based on these drawings without creative work.

[0013] In the traditional preparation method, due to the functional requirements of the product, such as reducing blue light, increasing brightness, etc., a functional adhesive layer is generally further prepared on the original fluorescent adhesive layer. The original fluorescent adhesive layer is usually doped with specific phosphors to achieve the excitation of the LED chip to emit light at a wavelength to form a specified color temperature and color rendering index; for example, in one example, in order to excite the blue light LED chip with a light output band of 440nm-460nm to form white light, the fluorescent adhesive layer contains yellow phosphor (YAG, yttrium aluminum garnet). In some other embodiments, the fluorescent adhesive layer includes yellow phosphor, green phosphor and red phosphor. In addition, the type and proportion of phosphor and silica gel in the first fluorescent adhesive layer can be adjusted according to the specific situation to adapt to different color rendering index and color temperature requirements, such as for color rendering. For scenes with higher index requirements (CRI>90), the types of phosphors can be appropriately increased, green phosphors and red phosphors can be added to the yellow phosphors, or a mixture of blue phosphors, green phosphors and red phosphors can be used, or even more color phosphors can be mixed together to increase the spectral composition of white light and more accurately display the true color of objects; for scenes with lower color temperature requirements (CCT<4200K), the phosphor mass fraction in the phosphor glue layer can generally be appropriately increased, and the phosphor mass fraction in the phosphor glue layer can be appropriately reduced in scenes with higher color temperature requirements (CCT>4200K). In this way, the types and proportions of phosphors can be adjusted based on the requirements of color temperature and color rendering index to meet the quality of white light.

[0014] The functional adhesive layer is used to meet special needs of the product in addition to the requirements for color temperature and color rendering index. For example, in one example, the functional adhesive layer includes monochrome phosphors and silica gel with a peak wavelength range of 470nm-500nm. The phosphors and silica gel are uniformly mixed in a certain mass ratio and then solidified. The layer is arranged on the surface of the fluorescent adhesive layer away from the light-emitting surface of the chip. After the fluorescent adhesive layer excites the light emitted by the blue light chip into white light, the monochrome phosphors in the functional adhesive layer further absorb the blue light that is harmful to the human body and convert it into cyan light (peak wavelength range of 470nm-500nm) that is harmless to the human body, thereby achieving the effect of reducing the intensity of the blue light.

[0015] However, the fluorescent film prepared by the traditional preparation process (first scraping glue to prepare the fluorescent glue layer and then scraping glue on the surface of the fluorescent glue layer to form a functional glue layer) has a problem that when the cut double-layer fluorescent film is sucked and mounted on the light-emitting surface of the LED chip, the suction nozzle that sucks the fluorescent film cannot remove the fluorescent film from the peeling film, resulting in inability to be used. The R&D personnel analyzed this phenomenon and found that: since the working principle of the suction nozzle is based on the difference in atmospheric pressure, when the adsorption device generates negative pressure, the pressure difference between the suction nozzle and the surface of the suction object will cause the suction object to be adsorbed on the surface of the suction nozzle. Specifically, when the suction nozzle is attached to the surface of the suction object, a closed space is formed inside the suction nozzle, and the air between the suction nozzle and the surface of the suction object is extracted, generating negative pressure. Due to the effect of atmospheric pressure, the suction object will be pushed to the surface of the suction nozzle by the atmospheric pressure and thus adsorbed on it. In addition, the flatness of the surface of the suction object will also affect the suction effect of the suction nozzle. If the surface flatness is poor or uneven, it will affect the degree of sealing between the suction nozzle and the surface of the suction object, resulting in poor adsorption effect. Therefore, the present invention improves the traditional preparation process so that the surface roughness of the second upper surface of the functional adhesive layer in the obtained fluorescent film is less than the surface roughness of the first lower surface of the fluorescent adhesive layer, that is, the surface of the functional adhesive layer that is subsequently used to be acted upon by the suction nozzle has a relatively flat and smooth surface, and when the suction nozzle used in the same traditional process is used for adsorption, the absorption and transfer of the double-layer fluorescent film can be smoothly achieved. It should be understood that in the fluorescent film obtained by the preparation method provided by the present invention, the surface roughness of the second upper surface of the functional adhesive layer exposed to the outside will be further less than the surface roughness of the upper surface of the functional adhesive layer exposed to the outside in the fluorescent film prepared by the traditional preparation process. Since the second upper surface of the functional adhesive layer in the fluorescent film prepared by the present invention has a relatively flat and smooth surface, it can be better used than the fluorescent film prepared by the traditional preparation process (preparing the fluorescent adhesive layer first, and then preparing the functional adhesive layer), and there will be no problem that the suction nozzle cannot remove it from the surface of the peeling film.

[0016] The specific contents of the plan are as follows: One embodiment of the present invention is a fluorescent film, comprising: a fluorescent glue layer, having a first upper surface and a first lower surface, the fluorescent glue layer is formed on the light-emitting surface of a blue light LED chip, and the first lower surface is arranged close to the light-emitting surface; the fluorescent glue layer emits white light under the excitation of the blue light LED chip; a functional glue layer, having a second upper surface and a second lower surface, the functional glue layer is formed on the surface of the fluorescent glue layer, and the fluorescent glue layer on the second lower surface is arranged close to the first upper surface of the fluorescent glue layer; the surface roughness of the second upper surface of the functional glue layer is less than the surface roughness of the first lower surface of the fluorescent glue layer.

[0017] The fluorescent film has two layers of structure, namely, a fluorescent glue layer and a functional glue layer. Usually, the two layers have the same shape and size. The fluorescent glue layer is made of fluorescent powder and silica gel, and the functional glue layer is also made of silica gel, which may be doped with at least one color of fluorescent powder or reflective particles. When it is applied to the LED chip, Figure 1 As shown, the fluorescent glue layer 11 is located in the lower layer, the first lower surface 112 directly contacts the light emitting surface of the blue light LED chip, the first upper surface 111 faces upward, and the functional glue layer 12 is located in the upper layer, the second lower surface 122 directly contacts the first upper surface 111, and the second upper surface 121 faces upward; the second lower surface of the functional glue layer and the first upper surface of the fluorescent glue layer are located on the same horizontal plane, contact each other and are tightly adhered together inside the fluorescent film, and for the entire fluorescent film, only the first lower surface 112 of the fluorescent glue layer and the second upper surface 121 of the functional glue layer are in contact with the external environment; wherein, the first lower surface of the fluorescent glue layer contacts and is adhered to the light emitting surface of the blue light LED chip through packaging, and the second upper surface of the functional glue layer is used to be absorbed in the packaging The suction nozzle is adsorbed, therefore, the surface roughness of the second upper surface plays an important role in the adsorption effect. According to the above, the better the flatness of the second upper surface, the more conducive it is to generate a larger adsorption force. The surface roughness of the second upper surface of the functional adhesive layer in this embodiment is less than the surface roughness of the first lower surface of the fluorescent adhesive layer. Therefore, when the suction nozzle acts on the second upper surface, the adsorption force generated is greater than the sum of the gravity of the fluorescent film itself and the adhesion force between the first lower surface of the fluorescent adhesive layer in the fluorescent film and the bottom peeling film. The fluorescent film can be easily sucked up from the original peeling film surface and transferred to the light-emitting surface of the blue LED chip. After the adsorption force of the suction nozzle is released, the relatively rougher first lower surface of the fluorescent adhesive layer is adhered to the light-emitting surface of the blue LED chip.

[0018] It should be emphasized that the functional adhesive layer itself is a functional structure for enhancing the luminous performance of the fluorescent film, wherein at least one color of fluorescent powder is doped to convert part of the wavelength of the excited white light, etc. In other embodiments, the fluorescent powder may not be doped, but reflective particles (such as TiO 2 etc.), to improve the uniformity of light output, etc.; that is, the functional adhesive layer itself is a structure for improving the luminous performance. In other words, this embodiment adopts a method of changing the preparation order to adjust the surface physical state of the functional adhesive layer, reduce its surface roughness, and increase its adsorption force when it is acted on by the suction nozzle, so that it can be smoothly absorbed and transferred.

[0019] Another embodiment of the present invention is a light-emitting device, comprising: a blue light LED chip, the blue light LED chip having a light-emitting top, a light-emitting side and an electrode side opposite to the light-emitting top; the above-mentioned fluorescent film, wherein the first lower surface of the fluorescent glue layer in the fluorescent film is mounted close to the light-emitting top of the blue light LED chip.

[0020] The light-emitting surface is the light-emitting surface of the blue LED chip. When the fluorescent film is pasted on the light-emitting surface, it is necessary to ensure that the fluorescent glue layer in the fluorescent film is in direct contact with the light-emitting surface, rather than the functional glue layer being in contact with the light-emitting surface. In this way, the light emitted from the light-emitting surface of the blue LED chip can better excite the fluorescent powder inside the fluorescent glue layer in the fluorescent film to emit white light, and further enter the functional glue layer to optimize the white light. Therefore, when the above-mentioned fluorescent film is applied to the light-emitting device, the fluorescent glue layer is located in the lower layer, and the functional glue layer is located in the upper layer, that is, the first lower surface of the fluorescent glue layer is in contact with the light-emitting surface of the blue LED chip through packaging and pasted together, and the second upper surface of the functional glue layer is placed upward. In other embodiments, the light-emitting device may also include a high-reflectivity white glue (TiO doped in the silica gel) at least surrounding the light-emitting side of the LED chip. 2 The high reflectivity particles can be used to make it have high reflectivity and reflect the light emitted from the side of the LED chip back), etc. It can be adjusted according to the actual application and is not specifically limited here.

[0021] Another embodiment of the present invention provides a method for preparing a fluorescent film, comprising the following steps: S01 forms a functional adhesive layer of a first thickness on the surface of the support film by scraping glue, and bakes it into a semi-cured state; the functional adhesive layer has a second upper surface and a second lower surface, and the second upper surface is a side surface close to the support film.

[0022] The support film referred to here serves to provide a support platform. Its surface is smooth and non-sticky, which makes it easy to separate the final fluorescent film from the support film after it is formed. It can be a release film, etc. The specific preparation process includes: first weighing a certain mass ratio of silica gel and auxiliary particles, the auxiliary particles can be fluorescent powder or reflective particles of a certain color, etc., and evenly stirring and mixing; then transferring the stirred material to the surface of the support film, using the scraper of the film making machine to act on the stirred material, and obtaining a functional adhesive layer of a certain thickness on the surface of the support film; finally, baking it under certain conditions to a semi-cured state (the surface is still sticky, but it has become adhesive and will not flow). Compared with the conditions for making ordinary fluorescent films fully cured, semi-curing is usually achieved by reducing the baking time or lowering the baking temperature. At this time, if Figure 2As shown, the second upper surface 121 (i.e., the surface at the bottom) in the functional adhesive layer 12 is directly in contact with the surface of the support film 20 at the bottom. Since the scraper exerts force on the functional adhesive layer, it is beneficial for the surface (second upper surface) at the bottom to form a closer contact with the support film, while the surface (second lower surface 122) on the other side forms a plane due to the free flow of the fluidity of the liquid after scraping, and there are also auxiliary particles in the functional adhesive layer, which leads to a larger roughness of the free-flowing plane. Therefore, the surface on the side of the functional adhesive layer that contacts the release film has a relatively smaller roughness, that is, the surface (second upper surface) at the bottom of the functional adhesive layer is smoother and flatter, while the surface (second lower surface) on the opposite side is a little rougher. The greater roughness of the second lower surface of the functional adhesive layer is beneficial to the subsequent attachment and adhesion of the fluorescent adhesive layer on its surface; through this control, not only can a relatively smoother second upper surface of the functional adhesive layer be obtained to facilitate suction by the suction nozzle, but it is also beneficial for the fluorescent adhesive layer to be more firmly adhered to the second lower surface of the functional adhesive layer.

[0023] The auxiliary particles can be phosphors of a certain color, which are excited by the light emitted by the chip to other colors, and can be used to change the emission wavelength, improve the spectrum, absorb blue light, etc. In one example, weigh silica gel with a mass of M1 and 5%-10% M1 mass of monochrome phosphor, and stir evenly and degas in vacuum. Place the stirred material on the support film, set the scraper height, scrape out a functional adhesive layer of a certain thickness (thickness less than 60µm), and bake the film at a temperature of 130°C for 0.5h to make it in a semi-cured state, that is, it loses a certain fluidity but the surface is not completely cured to form a functional adhesive layer. That is, at least one color of phosphor is evenly mixed with silica gel to form a functional adhesive layer of the first thickness on the surface of the support film, and then baked to a semi-cured state. The functional adhesive layer finally obtained is doped with at least one color of phosphor. At this time, the functional adhesive layer is in a semi-cured state and will not flow like a liquid substance, but it will not be as hard as a fully cured substance. The surface of the substance in this state shows a certain viscosity, which is conducive to the subsequent bonding with the fluorescent adhesive layer and avoids baking after curing to affect the properties of the functional adhesive layer, such as changing its chemical properties, causing shrinkage or deformation, etc. In another example, the auxiliary particles are TiO 2 The present embodiment does not impose any specific restrictions on the composition of the auxiliary particles of the reflective particles, as long as they can help improve the luminous performance in the fluorescent film.

[0024] S02 uniformly mixes the fluorescent powder and the silica gel, further forms a fluorescent glue layer of a second thickness on the surface of the functional glue layer by scraping glue, and bakes it to a fully cured state; the fluorescent glue layer has a first upper surface and a first lower surface, and the first upper surface is a side surface close to the functional glue layer; the fluorescent glue layer emits white light under the excitation of the blue light LED chip.

[0025] The surface roughness of the second upper surface of the functional adhesive layer is less than the surface roughness of the first lower surface of the fluorescent adhesive layer. The functional adhesive layer in the previous step and the supporting film at the bottom are placed on the work surface of the film making machine (the supporting film faces downward), the mixture of the fluorescent powder and the silica gel is transferred to the surface of the functional adhesive layer, and the scraper of the film making machine is used to act on the mixture to obtain a fluorescent adhesive layer of a certain thickness on the surface of the functional adhesive layer; and then completely cured under certain conditions to obtain a double-layer fluorescent film. At this time, if Figure 3 As shown, due to the force of the scraper, the first upper surface 111 of the fluorescent glue layer 11 (i.e., the bottom of the fluorescent glue layer) is tightly attached to the surface of the functional glue layer 12 (i.e., the second lower surface 122) (the first upper surface of the fluorescent glue layer and the second lower surface of the functional glue layer overlap), and the contact surface of the functional glue layer and the support film (the second upper surface 121) is also squeezed and stressed, which is conducive to making the second upper surface of the functional glue layer more flat and smooth, and further reducing the roughness. The first lower surface 112 of the fluorescent glue layer (i.e., the top of the fluorescent glue layer) does not have any external support or platform. After scraping the glue, the fluidity of the liquid flows freely to form a plane, and the fluorescent powder in the fluorescent glue layer will also cause the free-flowing plane to have a larger roughness. Therefore, its roughness after curing is relatively larger, that is, the surface roughness of the first lower surface of the fluorescent glue layer is greater than the surface roughness of the second upper surface of the functional glue layer.

[0026] In this embodiment, during the preparation process, the functional adhesive layer is directly formed on the surface of the support film by scraping glue, and the fluorescent adhesive layer is also formed on the surface of the functional adhesive layer by scraping glue, and is formed after the functional adhesive layer, that is, during the preparation process, the surface (second upper surface) where the functional adhesive layer contacts the support film is repeatedly subjected to downward extrusion external force, which is beneficial to reducing the roughness of the surface where the functional adhesive layer contacts the support film; this surface (second upper surface) has a relatively smaller surface roughness than the surface on the other side of the functional adhesive layer (second lower surface) and the surface of the fluorescent adhesive layer (including the first upper surface and the first lower surface), and when it is subsequently adsorbed by the suction nozzle, it can generate a larger adsorption force, which is greater than the sum of the gravity of the fluorescent film itself and the bonding force between the first lower surface of the fluorescent adhesive layer in the fluorescent film and the bottom peeling film, thereby realizing the transfer and application of the fluorescent film. The fluorescent film provided in this embodiment forms the fluorescent adhesive layer after the functional adhesive layer by simply changing the process sequence. Without changing any material, performance, etc. of the original fluorescent film, the surface of the functional adhesive layer for contacting the suction nozzle in the obtained double-layer fluorescent film is smoother and flatter, which effectively enhances the adsorption force, thereby successfully solving the problem that the fluorescent film cannot be sucked and transferred by the suction nozzle in the traditional process.

[0027] Another embodiment of the present invention provides a packaging method for a light emitting device, comprising the following steps: S01: transferring the entire fluorescent film obtained by the above preparation method to the surface of the first peeling film and cutting it; the first lower surface of the fluorescent adhesive layer adheres to the surface of the first peeling film, and the second upper surface of the functional adhesive layer is away from the first peeling film.

[0028] Since the area of ​​the double-layer film is usually much larger than that of a single LED chip, it needs to be further cut to a size suitable for the light-emitting surface of the LED chip, and the cut fluorescent film is adapted to the light-emitting surface of the blue LED chip: for fluorescent films with higher hardness (such as fluorescent films made of phenyl silicone), they need to be transferred to another sticky first peeling film surface for cutting to prevent the fluorescent film from breaking during the cutting process; for fluorescent films with lower hardness (such as fluorescent films made of methyl silicone), they have a certain toughness and are not easy to break during the cutting process, so they can be cut directly on the support film surface without transfer.

[0029] The first peeling film has a certain degree of stickiness, and can be released under special conditions, such as high temperature foaming film (released under high temperature), UV film (released by UV light), etc. When the fluorescent film is transferred from the surface of the support film to the surface of the first peeling film, the stickiness of the first peeling film can be used to stick the fluorescent film to achieve flip transfer of the fluorescent film. The state of the fluorescent film on the support film is: the second upper surface of the functional adhesive layer is facing downward and in contact with the surface of the support film, and the first lower surface of the fluorescent adhesive layer is placed upward; after the first lower surface of the fluorescent adhesive layer is stuck with the first peeling film, it is flipped and placed on a platform, such as Figure 4 As shown, at this time, the state of the fluorescent film on the first peeling film 30 is: the fluorescent adhesive layer 11 is at the bottom, and its first lower surface 112 is facing downward and in contact with the surface of the first peeling film, and the functional adhesive layer 12 is at the top, and its second upper surface 121 is facing upward. Then the whole piece of fluorescent film is cut, and the cutting depth is at least the thickness of the whole fluorescent film. The size and shape of the cutting are designed according to the light-emitting surface of the LED chip. If the light-emitting surface of the LED chip is square, the fluorescent film can be cut in a grid pattern. If the light-emitting surface of the LED chip is circular, the fluorescent film is cut into multiple independent circles. This embodiment does not limit this. The cutting method can be laser cutting or blade cutting; usually, it depends on the purpose of the fluorescent film: if the fluorescent film needs to be prepared into a special pattern, such as for a vertical chip or a normal chip, since there are electrodes on the light-emitting surface, it is necessary to remove the electrodes before sticking the fluorescent film on the light-emitting surface, and it cannot be formed by blade cutting, then laser cutting is required; if the fluorescent film needs to be cut into regular shapes that can be divided by a blade, such as squares, polygons, etc., then blade cutting can be used.

[0030] S04: transferring the entire cut fluorescent film sheet to the surface of the blue film for film expansion operation; the second upper surface of the functional adhesive layer adheres to the surface of the blue film, and the first lower surface of the fluorescent adhesive layer is away from the blue film.

[0031] After cutting, the stickiness of the first peeling film is released under specific conditions. The specific conditions here are different for different types of first peeling films; for example, if the first peeling film used is a high-temperature foaming film, the stickiness can be released by heating the cut fluorescent film; if the first peeling film used is a UV film, the stickiness can be released by irradiating the cut fluorescent film with UV light. This embodiment does not limit this. It is worth noting that when blade cutting is used, in order to protect the accuracy of the blade from being affected by the stickiness of the peeling film, before cutting, the area on the surface of the peeling film where no fluorescent film is formed is also released. Therefore, when blade cutting is used, UV film is usually required. UV light can be irradiated to the area where no fluorescent film is formed to release the stickiness, and then the blade cutting step is performed. Since the high-temperature foaming film can only be heated as a whole to release the stickiness of the entire surface, it cannot target a certain area. It is not suitable for blade cutting and is usually used in laser cutting. After the first peeling film is released, the fluorescent film on its surface is easily transferred by the blue film. Figure 5 As shown, the state of the fluorescent film 10 on the blue film 40 is: the functional adhesive layer 12 is at the bottom, and its second upper surface 121 is facing downward and in contact with the surface of the blue film, and the fluorescent adhesive layer 11 is at the top, and its first lower surface 112 is facing upward, which is the same as on the surface of the support film. Due to the good ductility of the blue film, as the blue film is expanded, the distance between the small pieces of fluorescent film 10 cut and separated on its surface is gradually enlarged to prevent mutual adhesion, which is convenient for subsequent transfer to the corresponding LED chip surface.

[0032] S05 transfers the entire fluorescent film sheet after expansion to the surface of the second peeling film, with the first lower surface of the fluorescent adhesive layer adhering to the surface of the first peeling film, and the second upper surface of the functional adhesive layer away from the second peeling film. During the preparation of the double-layer fluorescent film sheet, after two flips of the cutting and expansion process, the second upper surface of the functional adhesive layer is facing downward and in contact with the blue film; because the fluorescent adhesive layer in the double-layer fluorescent film sheet needs to directly contact the surface of the LED chip to function, before the fluorescent film sheet is sucked and transferred, it is necessary to flip it again through the second peeling film so that the second upper surface of the functional adhesive layer is facing upward, which is convenient for the suction nozzle to contact and suck. When transferring the fluorescent film sheet from the surface of the blue film to the surface of the second peeling film, the viscosity of the second peeling film can be used to stick the fluorescent film sheet to achieve the flipping transfer of the fluorescent film sheet. After flipping, such as Figure 6As shown, the state of the fluorescent film on the second stripping film 50 is: the fluorescent adhesive layer 11 is at the bottom, and its first lower surface 112 is facing downward and in contact with the surface of the first stripping film, and the functional adhesive layer 12 is at the top, and its second upper surface 121 is placed upward. The whole fluorescent film referred to here refers to the fluorescent film obtained through a preparation process during the preparation process, and the cutting and film expansion procedures have been completed. However, after the film expansion, the area occupied by the whole fluorescent film is much larger than the table of the machine. Therefore, the second stripping film can only transfer a part of it at a time. The fluorescent film transferred at a time can be half or 1 / 4 of the whole fluorescent film, etc., which can be determined according to the actual situation. It should be understood that before the absorption transfer, the fluorescent film can be turned over any number of times to perform other operations, as long as the second upper surface of the functional adhesive layer is facing upward during the absorption transfer, and the second stripping film used at this time should be able to release the stickiness, which can be a high-temperature foaming film or a UV film, etc., to facilitate the subsequent separation of the fluorescent film from the second stripping film.

[0033] S06: The cut fluorescent adhesive layer is transferred and mounted on the light-emitting surface of the blue LED chip by adsorbing the second upper surface of the functional adhesive layer through a suction nozzle; the first lower surface of the fluorescent adhesive layer is arranged close to the light-emitting surface.

[0034] After releasing the adhesiveness of the second release film, Figure 6 As shown, the suction nozzle 60 acts on the second upper surface of the functional adhesive layer. Since the surface roughness of the second upper surface of the functional adhesive layer is smaller than that of the first lower surface of the fluorescent adhesive layer, it is conducive to generating a stronger adsorption force. The adsorption force is greater than the sum of the gravity of the fluorescent film itself and the adhesive force between the first lower surface of the fluorescent adhesive layer in the fluorescent film and the bottom second peeling film, thereby sucking the fluorescent film off the second peeling film and transferring it to the light-emitting surface of the blue light LED chip. The method of removing the stickiness of the second peeling film is different for different types of second peeling films; for example, the second peeling film used is a high-temperature foaming film, and the stickiness can be removed by heating it; the second peeling film used is a UV film, and the stickiness can be removed by irradiating it with UV light. This embodiment does not limit this. The suction nozzle approaches the second upper surface of the functional adhesive layer of the fluorescent film from above, and after forming a close contact with the surface of the functional adhesive layer, the suction force is formed by negative pressure to remove the fluorescent film from the second peeling film after the stickiness is removed. The suction nozzle keeps negative pressure during the process of transferring the fluorescent film to prevent the fluorescent film from falling off; until the suction nozzle reaches the position corresponding to the surface of the LED chip, the negative pressure provided to the suction nozzle is stopped, the adsorption force disappears, and the fluorescent film is attached to the surface of the LED chip. In addition, after the fluorescent film is attached, the packaging process may also include placing white glue around the LED chip to prevent light from emitting from the side; and forming a lens on the light emitting surface to focus the light emission angle, etc.; this embodiment does not limit this.

[0035] When the above fluorescent film is encapsulated on the blue LED chip of the flip-chip structure, the first peeling film usually used in the process of cutting the fluorescent film is a UV film, and the second peeling film used after the film expansion is a high-temperature foaming film. The flip-chip LED chip has a light-emitting top, a light-emitting side, and an electrode side opposite to the light-emitting top. The electrode is located on the other side opposite to the light-emitting surface, and the light-emitting surface is mostly regular in shape. Therefore, the fluorescent film can be cut by a blade. In order to protect the accuracy of the blade from being affected by the viscosity of the first peeling film, after the entire fluorescent film is transferred to the surface of the first peeling film, before cutting, it also includes the operation of removing the viscosity of the area on the surface of the first peeling film where the fluorescent film is not formed. Therefore, when the blade cutting method is adopted, UV film is usually required. UV light can be irradiated to the area where the fluorescent film is not formed to remove the viscosity, and then the blade cutting step is performed; when the blade is cut, it is planned according to the shape and size of the light-emitting surface of the blue LED chip, so that the small piece of fluorescent film after cutting is adapted to the light-emitting surface. Since the high-temperature foaming film can only be heated as a whole to remove the viscosity of the entire surface, it cannot be targeted at a certain area and is not suitable for blade cutting. The second peeling film is a high-temperature foaming film. After the adhesiveness is released at high temperature, the fluorescent film can be transferred to the light-emitting surface of the blue light LED chip of the corresponding flip-chip structure through a suction nozzle.

[0036] When the above fluorescent film is packaged for a blue LED chip with a vertical structure or a normal structure, the first stripping film used in the process of cutting the fluorescent film is usually a high-temperature foaming film, and the second stripping film used after the film expansion is also a high-temperature foaming film. The electrode of the vertical structure or the normal structure is located on the surface of the light-emitting surface. Regardless of whether the light-emitting surface is a regular shape, the position of the electrode will affect the shape of the fluorescent film. The fluorescent film used needs to remove the position of the electrode, so it is necessary to use laser cutting to process the fluorescent film, and the first stripping film used in cutting usually needs to use a high-temperature foaming film. When laser cutting the fluorescent film on the first stripping film, a laser is used to punch holes in the fluorescent film at a preset position on the surface of the first stripping film (i.e., the position of the electrode on the light-emitting surface of each LED chip), and then the shape and size of the light-emitting surface of the blue LED chip are planned, and the entire fluorescent film after punching is also cut by laser, so that the small piece of fluorescent film after cutting is adapted to the light-emitting surface, and each cut fluorescent film includes a through hole matching the position of the electrode on the surface of the blue LED chip. Usually, there is an electrode on the light-emitting surface of a vertical chip, and the fluorescent film used also has a through hole formed at the position of the electrode; there are two electrodes on the light-emitting surface of a positive chip, and the fluorescent film used has through holes formed at the positions of the two electrodes respectively. The second peeling film is a high-temperature foaming film. After the high temperature releases the viscosity, the fluorescent film can be transferred to the light-emitting surface of the blue light LED chip of the corresponding flip-chip structure through a suction nozzle. It should be understood that the number or position and shape of the through holes formed in the fluorescent film in this process are determined by the structure of the LED chip, and the electrode position on the light-emitting surface of the LED chip is exposed by cutting or forming through holes on the surface of the fluorescent film. For example, in an application, if the surface of the light-emitting surface of the LED chip is configured with three electrodes, three through holes are formed on the surface of the fluorescent film; if the surface of the light-emitting surface of the LED chip is formed with a long strip electrode, the corresponding position on the surface of the fluorescent film is cut and removed.

[0037] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A fluorescent film, characterized in that: include: A fluorescent glue layer having a first upper surface and a first lower surface, wherein the fluorescent glue layer is formed on the light emitting surface of the blue light LED chip, and the first lower surface is disposed close to the light emitting surface; The fluorescent glue layer emits white light under the excitation of the blue light LED chip; A functional adhesive layer having a second upper surface and a second lower surface, wherein the functional adhesive layer is formed on the surface of the fluorescent adhesive layer, and the fluorescent adhesive layer on the second lower surface is disposed close to the first upper surface of the fluorescent adhesive layer; The surface roughness of the second upper surface of the functional adhesive layer is smaller than the surface roughness of the first lower surface of the fluorescent adhesive layer.

2. The fluorescent film according to claim 1, characterized in that: The functional adhesive layer is doped with fluorescent powder of at least one color.

3. A light emitting device, characterized in that: The light emitting device comprises: A blue LED chip, wherein the blue LED chip has a light-emitting top surface, a light-emitting side surface, and an electrode side surface opposite to the light-emitting top surface; The fluorescent film as claimed in claim 1 or 2, wherein the first lower surface of the fluorescent glue layer in the fluorescent film is mounted close to the light-emitting upper surface of the blue light LED chip.

4. A method for preparing a fluorescent film, characterized in that: The following steps are involved: A functional adhesive layer of a first thickness is formed on the surface of the support film by scraping glue, and baked into a semi-cured state; the functional adhesive layer has a second upper surface and a second lower surface, and the second upper surface is a side surface close to the support film; The fluorescent powder and the silica gel are uniformly mixed, and a fluorescent glue layer of a second thickness is further formed on the surface of the functional glue layer by scraping glue, and baked to a completely solidified state; the fluorescent glue layer has a first upper surface and a first lower surface, and the first upper surface is a side surface close to the functional glue layer; the fluorescent glue layer emits white light under the excitation of the blue light LED chip; The surface roughness of the second upper surface of the functional adhesive layer is smaller than the surface roughness of the first lower surface of the fluorescent adhesive layer.

5. The method for preparing the fluorescent film according to claim 4, characterized in that: The functional adhesive layer is doped with fluorescent powder of at least one color; The method of forming a functional adhesive layer of a first thickness on the surface of the support film by scraping glue and baking it to a semi-cured state includes: uniformly mixing at least one color of fluorescent powder with silica gel to form a functional adhesive layer of a first thickness on the surface of the support film, and baking it to a semi-cured state.

6. A packaging method for a light emitting device, characterized in that: The following steps are involved: Transferring the entire fluorescent film sheet prepared in claim 5 to the surface of the first peeling film and cutting it, wherein the first lower surface of the fluorescent adhesive layer adheres to the surface of the first peeling film, and the second upper surface of the functional adhesive layer is away from the first peeling film; The entire fluorescent film sheet after cutting is transferred to the surface of the blue film for film expansion operation, the second upper surface of the functional adhesive layer is adhered to the surface of the blue film, and the first lower surface of the fluorescent adhesive layer is away from the blue film; Transferring the entire fluorescent film sheet after film expansion to the surface of the second peeling film, wherein the first lower surface of the fluorescent adhesive layer adheres to the surface of the first peeling film, and the second upper surface of the functional adhesive layer is away from the second peeling film; The cut fluorescent adhesive layer is transferred and mounted on the light-emitting surface of the blue LED chip by adsorbing the second upper surface of the functional adhesive layer with a suction nozzle; the first lower surface of the fluorescent adhesive layer is arranged close to the light-emitting surface.

7. The packaging method according to claim 6, characterized in that: The first stripping film is a UV film, and the second stripping film is a high-temperature foaming film.

8. The packaging method according to claim 7, characterized in that: In the process of transferring the entire fluorescent film sheet prepared in claim 5 to the surface of the first peeling film and cutting it, a blade is used to cut the entire fluorescent film sheet on the surface of the first peeling film, and the cut fluorescent film sheet is adapted to the light-emitting surface of the blue light LED chip.

9. The packaging method according to claim 6, characterized in that: The first peeling film and the second peeling film are both high-temperature foaming films.

10. The packaging method according to claim 9, characterized in that: The step of transferring the entire fluorescent film sheet prepared in claim 5 to the surface of the first peeling film and cutting the film comprises: Using laser to perform a hole punching operation at a preset position on the surface of the first peeling film; The whole fluorescent film after punching is cut by laser, and the cut fluorescent film is adapted to the light-emitting surface of the blue light LED chip, and each cut fluorescent film includes a through hole matching the position of the electrode on the surface of the blue light LED chip.

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