CN113604164B - FPC photosensitive cover film for MiniLED - Google Patents

FPC photosensitive cover film for MiniLED Download PDF

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Publication number
CN113604164B
CN113604164B CN202110890201.3A CN202110890201A CN113604164B CN 113604164 B CN113604164 B CN 113604164B CN 202110890201 A CN202110890201 A CN 202110890201A CN 113604164 B CN113604164 B CN 113604164B
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photosensitive
fpc
miniled
layer
adhesive layer
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CN113604164A (en
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闫勇
高小君
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Kunshan Zhuoyue Lantian Electronic Technology Co ltd
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Suzhou Chengbang Dayi Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/04—Non-macromolecular additives inorganic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/25—Plastics; Metallised plastics based on macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/255—Polyesters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/40—Adhesives in the form of films or foils characterised by release liners
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
    • C09J2301/12—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers
    • C09J2301/122—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers the adhesive layer being present only on one side of the carrier, e.g. single-sided adhesive tape
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2433/00—Presence of (meth)acrylic polymer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2467/00—Presence of polyester
    • C09J2467/006—Presence of polyester in the substrate

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Non-Metallic Protective Coatings For Printed Circuits (AREA)
  • Materials For Photolithography (AREA)

Abstract

The invention provides an FPC photosensitive covering film for MiniLED, which is white and sequentially comprises the following components from bottom to top: the carrier layer and/or the release layer and the photosensitive adhesive layer have the contact surface roughness of 0.3-1 mu m, so that the following technical effects are realized: (1) In the FPC manufacturing procedure of the MiniLED, the white photosensitive covering film is used for replacing white ink, so that the printing and baking processes of the white ink are reduced, the process efficiency is improved, in addition, the defects that the white ink is easily influenced by the environment, such as impurities and foreign matters caused by the white ink or the environment, are also reduced, and the yield of the FPC of the MiniLED is improved; (2) The roughness of the contact surface between the carrier layer and/or the release layer of the white photosensitive covering film and the photosensitive adhesive layer is 0.3-1 μm, so that the roughness of the photosensitive adhesive layer is greatly increased, the binding force between the photosensitive adhesive layer and the related materials of the FPC of the MiniLED is greatly improved, and the defects or defects of layering, warping and the like of the FPC are avoided.

Description

FPC photosensitive cover film for MiniLED
Technical Field
The invention relates to the technical field of electronic materials, in particular to an FPC photosensitive cover film for a MiniLED.
Background
MiniLED, i.e., a mini light emitting diode, is much smaller than a normal LED, only 50-200 microns. Within the same large screen size, the unit area density of MiniLED is higher, and the unit size of light source is smaller, thus can bring higher luminance and controllable color gamut, the picture quality is more bright, can present more detailed display picture. In addition, miniLED also has the advantages of high protection, large visual angle, high PPI, high contrast, etc., and MiniLED is inevitably the mainstream display technology in the coming years.
In the preparation process of the MiniLED, on a Flexible Printed Circuit (FPC for short) used by the MiniLED, a white ink is adopted in a traditional process, and on one hand, the white ink requires two processes of printing and baking in the manufacturing process, so that the preparation efficiency is low, and in addition, the use of the white ink is influenced by foreign matters or impurities to reduce the yield of the MiniLED, so that a photosensitive cover film is urgently needed to replace the white ink so as to improve the FPC manufacturing efficiency for the MiniLED.
In view of this, development of a photosensitive cover film material of FPC for MiniLED has been made to solve the above problems.
Disclosure of Invention
The invention aims to disclose an FPC photosensitive cover film for a MiniLED, which replaces the existing white ink with a white photosensitive cover film, on one hand, the surface roughness of a photosensitive adhesive layer is increased through the roughness of a carrier layer and/or a release layer of the white photosensitive cover film, so that the binding force between the photosensitive adhesive layer and the related materials of the FPC is further increased, and on the other hand, the white photosensitive cover film is not yellowed through the improvement of the formula of the photosensitive adhesive layer of the white photosensitive cover film, so that the FPC stability of the MiniLED is improved.
In order to achieve the above object, the present invention provides a FPC photosensitive coverlay for MiniLED, the photosensitive coverlay is white and comprises, in order from bottom to top: the photosensitive adhesive layer comprises a carrier layer, a photosensitive adhesive layer and a release layer, wherein the roughness of the contact surface of the carrier layer and/or the release layer and the photosensitive adhesive layer is 0.3-1 mu m.
Preferably, the carrier layer is made of PET.
Preferably, the preparation process of the carrier layer or the release layer comprises a calendering process of a calendering roller, wherein a plurality of protrusions are arranged on the surface of the calendering roller, and the surface roughness of the calendering roller is 0.3-1 μm.
Preferably, the protrusions are spherical and evenly distributed.
Preferably, the protrusion is in the shape of an elongated strip, and the direction of the elongated strip is non-directional.
Preferably, the protrusions are a combination of elongated and spherical.
Preferably, the support layer has a light transmission of greater than 95% and a thickness of 15 μm to 75 μm.
Preferably, the formula of the photosensitive adhesive layer comprises, by weight, 40-50 parts of acrylic resin, 10-15 parts of epoxy resin, 3-6 parts of curing agent, 0.5-2 parts of photoinitiator and 35-40 parts of titanium dioxide.
Preferably, the release layer is made of PET or PE, the release force between the release layer and the photosensitive adhesive layer is 10g/mm-100g/mm, and the thickness is 15 μm-75 μm.
Preferably, the curing agent is one or more of diaminodiphenyl sulfone, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, and the photoinitiator is one or more of photoinitiator TPO, photoinitiator 184 and photoinitiator 819.
Compared with the prior art, the invention has the beneficial effects that:
(1) In the FPC manufacturing process of the MiniLED, the white photosensitive covering film is used for replacing white ink, so that the printing and baking manufacturing processes of the white ink are reduced, the process efficiency is improved, in addition, the defects that the white ink is easily influenced by the environment, such as impurities and foreign matters caused by the white ink or the environment, are also reduced, and the FPC yield of the MiniLED is improved;
(2) The roughness of the contact surface between the carrier layer and/or the release layer of the white photosensitive cover film and the photosensitive adhesive layer is 0.3-1 μm, so that the roughness of the carrier layer and/or the release layer is greatly increased, the surface roughness of the photosensitive adhesive layer is greatly improved, the carrier layer and the release layer are removed in the FPC manufacturing process, the bonding force between the photosensitive adhesive layer and the FPC related materials is increased, and the defects such as layering, warping and the like of the FPC are avoided;
(3) The photosensitive adhesive layer of the white photosensitive covering film is made of colorless transparent resin and a non-yellowing curing agent, and a certain amount of titanium dioxide is added, so that the white photosensitive covering film is not yellowed on one hand, and has high reflectivity on the other hand, and the display effect of the MiniLED is better;
(4) Under the irradiation of ultraviolet light, carboxyl of acrylic resin of the photosensitive adhesive layer and free radicals of a photoinitiator are subjected to reaction curing reaction, so that the acrylic resin is completely cured, and the pores are smaller after the acrylic resin is cured, so that more LED chip openings can be arranged in the unit area of the photosensitive layer of the photosensitive cover film, the LED chip openings are reduced to 50 micrometers, the LED chips are arranged at the openings, and light is reflected through the photosensitive layer of the photosensitive cover film at the openings; when the opening of the LED chip is reduced to 50 micrometers, the LED chip can also be 50 micrometers in size, so that more LED chips are arranged in the unit area of the FPC of the MiniLED, the reflection effect of the MiniLED is better, and the MiniLED can be used for 4k and 8k high-definition display screens.
Drawings
FIG. 1 is a schematic cross-sectional view of a layered structure of a photosensitive cover film according to the present invention;
FIG. 2 is a schematic view of the surface of the calender roll showing the spherical protrusions of the present invention;
FIG. 3 is a schematic view of the elongated projections on the surface of a calender roll of the present invention;
FIG. 4 is a schematic view of the surface of the calendar roll showing the spherical protrusions and elongated protrusions of the present invention;
fig. 5 is a test result of the roughness and the bonding force of the carrier layer and the release layer according to the present invention.
Wherein, 1, a carrier layer; 2. a photosensitive adhesive layer; 3. and a release layer.
Detailed Description
The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplification of the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
Definition of terms:
acrylic resin: are a generic term for polymers of acrylic acid, methacrylic acid and derivatives thereof.
Epoxy resin: the material is a high temperature resistant material, can bear the high temperature of at least 300 ℃, and can be bisphenol A type epoxy resin or biphenyl type epoxy resin; the bisphenol A type epoxy resin is a substrate of the photosensitive adhesive layer, and has strong adhesion after curing, acid and alkali resistance, high mechanical strength, good electrical insulation and corrosion resistance; the biphenyl epoxy resin has the characteristics of low melt viscosity, excellent adhesion, low surface stress and small expansion coefficient after molding.
Curing agent: also called as hardener and curing agent, and the curing agent is added to enable the photosensitive adhesive layer to be cured on the carrier layer during exposure.
Photoinitiator (2): also called as photosensitizer or light curing agent, is a compound which absorbs energy with certain wavelength in an ultraviolet region (250 nm-420 nm) or a visible light region (400 nm-800 nm) to generate free radicals, cations and the like so as to cure the curing agent.
The photoinitiator 819: is an acylphosphine oxide photoinitiator, the chemical name of which is phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide, the Chinese name of which is photoinitiator 819.
Photoinitiator 184: the Chinese name is 1-hydroxycyclohexyl phenyl ketone, the chemical formula is C 13 H 16 O 2 White crystals, is a highly efficient free radical type I non-yellowing photoinitiator for UV polymerization of mono-or polyfunctional acrylate monomers and oligomers.
Photoinitiator TPO: the Chinese name is diphenyl- (2, 4, 6-trimethyl benzoyl) oxyphosphorus, and the chemical formula is C 22 H 21 O 2 P, high photocuring speed, photobleaching effect, suitability for deep curing and no yellowing of the coating.
The following describes a specific implementation process of the present invention by using a plurality of embodiments.
The first embodiment is as follows:
as shown in fig. 1, the FPC photosensitive coverlay for MiniLED is white, and sequentially includes, from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, carrier layer 1 with from type layer 3 with the contact surface roughness of sensitization glue film 2 is 0.3 mu m, the carrier layer is the PET material, carrier layer luminousness 95%, for thickness 15 mu m, carrier layer 1 and the preparation technology from type layer 3 include the calendering process of calendering roller, the surface of calendering roller sets up a plurality of archs, the surface roughness of calendering roller is 0.3 mu m, as shown in figure 2, the arch is globular and evenly distributed, and in this embodiment, the roughness is arithmetic mean value.
It should be further noted that calendering is one of the processes for forming PET or PE materials, and is to pass the plasticized thermoplastic material close to viscous flow temperature through a series of horizontal roll gaps rotating in opposite directions to subject the material to extrusion and stretching to form a sheet-like product with a certain thickness, width and smooth surface. In this embodiment, the lower roll surface of the calendering roll is provided with a plurality of uniformly distributed spherical protrusions, so that the roughness of the lower roll surface of the calendering roll is 0.3 μm, the spherical protrusions enable the surface of the PET or PE to form spherical pits, the roughness of the surface of the PET or PE is improved, the surface roughness of the photosensitive adhesive layer is also improved in the process of preparing the photosensitive cover film, the carrier layer and the release layer can be removed when the photosensitive cover film is used and the FPC is manufactured, and therefore the bonding force between the photosensitive adhesive layer and the related material of the FPC is improved, the related material of the FPC can be an FPC base material or a copper foil and the like, and the defects of layering, warping and the like of the FPC are avoided.
It is further noted that the formula of the photosensitive adhesive layer comprises, by weight, 50 parts of acrylic resin, 11 parts of epoxy resin, 3.5 parts of curing agent, 0.5 part of photoinitiator and 35 parts of titanium dioxide; from type layer material PET or PE, from the type layer with the sensitization glue film from the type power be 10g/mm, thickness 15 mu m, from the type layer as the protection film, when using the sensitization to cover the membrane, can tear off from the type layer.
In this embodiment, the acrylic resin is added as a solvent, and specifically, may be one or more of a full-acrylic resin, a styrene-acrylic resin, a silicone-acrylic resin, a vinyl acetate-acrylic resin, a fluorine-acrylic resin, or a tertiary acrylic resin, and may be mixed with acrylic resins having different polymerization degrees.
In this embodiment, all use biphenyl type epoxy for the sensitization glue film is more stable, is difficult to the crackle.
Acrylic resin, biphenyl type epoxy resin and the like are colorless transparent resins, so that the use of the acrylic resin and the biphenyl type epoxy resin does not affect the light transmittance of the photosensitive adhesive layer.
In this embodiment, the curing agent is one or a combination of more of diaminodiphenyl sulfone, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride, and after the curing agent is polymerized with the epoxy resin, the polymer formed does not yellow, for example, diaminodiphenyl sulfone does not have free amine, which avoids yellowing caused by direct polymerization of free amine with the epoxy resin, and tetrahydrophthalic anhydride and hexahydrophthalic anhydride do not have amino group, do not generate free amine, and do not have basic group of yellowing, so the photosensitive cover film of this embodiment does not yellow under long-time irradiation of the LED lamp, remains white, and ensures the reflection effect of MiniLED.
In this embodiment, the pigment, the filler and the flame retardant are all white titanium dioxide, which is an important inorganic chemical pigment, the main component is titanium dioxide, the pigment stability is good, and the titanium dioxide is used as the filler and the pigment, so that the finally formed photosensitive adhesive layer has high reflectivity to the LED light.
In the present embodiment, the photoinitiator is one or a combination of photoinitiators TPO, 184 and 819; the photoinitiator 819 is used as acylphosphine oxide, and the photoinitiator 819 hardly yellows after curing and under the condition of long-term light radiation, so that the photoinitiators can be used in occasions with strict requirements on yellowing; both the photoinitiator TPO and the photoinitiator 184 have the performance of not easily turning yellow after film formation, so that the photoinitiator selected in the embodiment cannot cause the light-sensitive covering film to turn yellow, thereby ensuring the reflection effect of the MiniLED.
Through this embodiment, realize following technological effect: (1) In the FPC manufacturing process of the MiniLED, the white photosensitive covering film is used for replacing white ink, so that the printing and baking manufacturing processes of the white ink are reduced, the process efficiency is improved, in addition, the defects that the white ink is easily influenced by the environment, such as impurities and foreign matters caused by the white ink or the environment, are also reduced, and the yield of the MiniLED is improved;
(2) The roughness of the contact surfaces of the carrier layer and the release layer of the white photosensitive cover film and the photosensitive adhesive layer is 0.3 mu m, so that the roughness of the carrier layer and the release layer is greatly increased, the surface roughness of the photosensitive adhesive layer is also improved in the process of preparing the photosensitive cover film, and the carrier layer and the release layer are removed in the process of manufacturing the FPC and using the photosensitive cover film, so that the binding force between the photosensitive adhesive layer and the related materials of the FPC is improved, and the defects of layering, warping and the like of the FPC are avoided;
(3) The photosensitive adhesive layer of the white photosensitive covering film adopts colorless transparent resin, a non-yellowing curing agent and a non-yellowing photoinitiator, and a certain amount of titanium dioxide is added, so that the titanium dioxide is not yellowed, the white photosensitive covering film is not yellowed on one hand, the reflectivity is high on the other hand, and the display effect of a MiniLED is better;
(4) Under the irradiation of ultraviolet light, carboxyl of acrylic resin of the photosensitive adhesive layer and free radicals of a photoinitiator are subjected to reaction curing reaction, so that the acrylic resin is completely cured, and the pores are smaller after the acrylic resin is cured, so that more LED chip openings can be arranged in a unit area of the photosensitive covering film, the LED chip openings are reduced to 50 micrometers, and each opening can be provided with one LED chip, so that more LED chips can be arranged in the unit area.
Example two:
the difference from the first embodiment is that the roughness of the contact surfaces of the carrier layer 1 and the release layer 3 and the photosensitive adhesive layer 2 is 0.5 μm, and the surface roughness of the calendering roller is 0.5 μm.
The technical solution disclosed in the second embodiment has the same components as those in the first embodiment, please refer to the description of the first embodiment, which is not repeated herein.
Example three:
the difference from the first embodiment is that the roughness of the contact surfaces of the carrier layer 1 and the release layer 3 with the photosensitive adhesive layer 2 is 1 μm, and the surface roughness of the calendering roller is 1 μm.
The technical solutions disclosed in the third embodiment and the first embodiment have the same components, and please refer to the description of the first embodiment, which will not be repeated herein.
Example four:
as shown in fig. 1, the FPC photosensitive coverlay for MiniLED is white, and includes, in order from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, carrier layer 1 with the contact surface roughness of sensitization glue film 2 is 0.3 mu m, the carrier layer is the PET material, carrier layer luminousness is 98%, for thickness 75 mu m, the preparation technology of carrier layer includes the calendering process of calendering roller, the surface of calendering roller sets up a plurality of archs, the surface roughness of calendering roller is 0.3 mu m, as shown in figure 2, the arch is globular and evenly distributed, and in this embodiment, the roughness is arithmetic mean.
It should be further noted that calendering is one of the processes for forming PET materials, and is to pass the plasticized thermoplastic plastics close to viscous flow temperature through a series of horizontal roller gaps rotating in opposite directions, so that the material is subjected to extrusion and stretching, and becomes a sheet-like product with a certain thickness, width and smooth surface. In the embodiment, the surface of the lower roller of the calendering roller is provided with a plurality of uniformly distributed spherical protrusions, so that the roughness of the surface of the lower roller of the calendering roller is 0.3 mu m, the spherical protrusions enable the surface of PET to form spherical pits, the roughness of the surface of PET is improved, the surface roughness of a photosensitive adhesive layer is also improved in the process of preparing the photosensitive cover film, and when an FPC (flexible printed circuit) is manufactured and the photosensitive cover film is used, the carrier layer can be removed, so that the bonding force between the photosensitive adhesive layer and related materials of the FPC is improved, the related materials of the FPC can be FPC base materials or copper foils and the like, and the defects or defects of layering, warping and the like of the FPC are avoided.
The formula of the photosensitive adhesive layer comprises, by weight, 40 parts of acrylic resin, 15 parts of epoxy resin, 3 parts of curing agent, 2 parts of photoinitiator and 40 parts of titanium dioxide; from type layer material PET or PE, from the type layer with the sensitization glue film from the type power be 100g/mm, thickness 75 mu m, from the type layer as the protection film, when using the sensitization to cover the membrane, can tear off from the type layer.
In this embodiment, the acrylic resin is added by a solvent, and specifically may be one or more of a full-acrylic resin, a styrene-acrylic resin, a silicone-acrylic resin, a vinyl-acrylic resin, a fluoro-acrylic resin, or a t-acrylic resin, and further, acrylic resins having different polymerization degrees may be used in combination.
In this embodiment, all biphenyl type epoxy resin is used, so that the photosensitive adhesive layer is more stable and is not easy to crack.
Since acrylic resin, biphenyl type epoxy resin, and the like are colorless transparent resins, the use of acrylic resin, bisphenol a type epoxy resin, biphenyl type epoxy resin does not affect the light transmittance of the photosensitive layer.
In this embodiment, the curing agent is one or a combination of more of diaminodiphenyl sulfone, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, and after the curing agent is polymerized with the epoxy resin, the formed polymer does not yellow, for example, diaminodiphenyl sulfone does not have free amine, so that yellowing caused by direct polymerization of free amine with the epoxy resin is avoided, and tetrahydrophthalic anhydride and hexahydrophthalic anhydride do not have amino group, do not generate free amine, and do not have basic group of yellowing, so that the photosensitive cover film of this embodiment does not yellow under long-time irradiation of LED lamps, remains white, and ensures the reflection effect of MiniLED.
In this embodiment, the pigment, the filler and the flame retardant are all white titanium dioxide, which is an important inorganic chemical pigment, the main component is titanium dioxide, the pigment stability is good, and the titanium dioxide is used as the filler and the pigment, so that the finally formed photosensitive adhesive layer has high reflectivity to the LED light.
In the present embodiment, the photoinitiator is one or a combination of photoinitiators TPO, 184 and 819; the photoinitiator 819 is used as an acylphosphine oxide, and the photoinitiator 819 hardly undergoes yellowing after curing and under the condition of long-term light irradiation, so that the photoinitiators can be used in occasions with strict requirements on yellowing; both the photoinitiator TPO and the photoinitiator 184 have the performance of not easily turning yellow after film forming, so that the photoinitiator selected by the embodiment cannot cause the photosensitive covering film to turn yellow, thereby ensuring the reflection effect of the MiniLED.
Through this embodiment, realize following technological effect: (1) In the FPC process of the MiniLED, the white photosensitive covering film is used for replacing white ink, so that the printing and baking processes of the white ink are reduced, the process efficiency is improved, in addition, the defects that the white ink is easily influenced by the environment, such as impurities and foreign matters caused by the white ink or the environment, are also reduced, and the yield of the MiniLED is improved;
(2) The roughness of the contact surface of the carrier layer of the white photosensitive covering film and the photosensitive adhesive layer is 0.3 mu m, so that the roughness of the carrier layer is greatly increased, the surface roughness of the photosensitive adhesive layer is also improved in the process of preparing the photosensitive covering film, and the carrier layer and the release layer are removed in the process of manufacturing the FPC and using the photosensitive covering film, so that the binding force between the photosensitive adhesive layer and the related materials of the FPC is improved, and the defects of layering, warping and the like of the FPC are avoided;
(3) The photosensitive adhesive layer of the white photosensitive covering film adopts colorless transparent resin, a non-yellowing curing agent and a non-yellowing photoinitiator, and a certain amount of titanium dioxide is added, so that the titanium dioxide is not yellowed, the white photosensitive covering film is not yellowed on one hand, and the reflectivity is high on the other hand, and the display effect of a MiniLED is better;
(4) Under the irradiation of ultraviolet light, carboxyl of acrylic resin of the photosensitive adhesive layer and free radicals of a photoinitiator are subjected to reaction curing reaction, so that the acrylic resin is completely cured, and the pores are smaller after the acrylic resin is cured, so that more LED chip openings can be arranged in a unit area of the photosensitive covering film, the LED chip openings are reduced to 50 micrometers, and each opening can be provided with one LED chip, so that more LED chips can be arranged in the unit area.
Example five:
the difference from the fourth embodiment is that the roughness of the contact surface of the carrier layer 1 and the photosensitive adhesive layer 2 is 0.5 μm, and the surface roughness of the calendering roller is 0.5 μm.
The technical solutions disclosed in the fifth embodiment and the fourth embodiment have the same components, please refer to the description of the fourth embodiment, and details are not repeated herein.
Example six:
the difference from the fourth embodiment is that the roughness of the contact surface of the support layer 1 and the photosensitive glue layer 2 is 1 μm, and the surface roughness of the calendering roller is 1 μm.
The technical solutions disclosed in the sixth embodiment and the fourth embodiment have the same parts, please refer to the description of the fourth embodiment, and details are not repeated herein.
Example seven:
as shown in fig. 1, the FPC photosensitive coverlay for MiniLED is white, and sequentially includes, from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, from type layer 3 with sensitization glue film 2's contact surface roughness is 0.3 mu m, the carrier layer is the PET material, the carrier layer luminousness is 97%, for thickness 75 mu m, the preparation technology from type layer 3 includes the calendering process of calendering roller, the surface of calendering roller sets up a plurality of archs, the surface roughness of calendering roller is 0.3 mu m, as shown in figure 2, the arch is globular and evenly distributed, and in this embodiment, the roughness is arithmetic mean value.
It should be further noted that calendering is one of the processes for forming PET or PE materials, and is to pass the plasticized thermoplastic plastics close to viscous flow temperature through a series of horizontal roller gaps rotating in opposite directions to subject the material to extrusion and stretching, so as to form a sheet-like product with a certain thickness, width and smooth surface. In this embodiment, the lower roll surface of the calendering roll is provided with a plurality of uniformly distributed spherical protrusions, so that the roughness of the lower roll surface of the calendering roll is 0.3 μm, the spherical protrusions enable the surface of the PET or PE to form spherical pits, the roughness of the surface of the PET or PE is improved, the surface roughness of the photosensitive adhesive layer is also improved in the process of preparing the photosensitive cover film, the carrier layer can be removed when the photosensitive cover film is used for manufacturing an FPC (flexible printed circuit), and therefore the bonding force between the photosensitive adhesive layer and related materials of the FPC is improved, the related materials of the FPC can be an FPC base material or a copper foil and the like, and defects or defects of layering, warping and the like of the FPC are avoided.
The formula of the photosensitive adhesive layer comprises, by weight, 45 parts of acrylic resin, 12.5 parts of epoxy resin, 3.5 parts of a curing agent, 2 parts of a photoinitiator and 37 parts of titanium dioxide; from type layer material PET or PE, from the type layer with the sensitization glue film from the type power for 50g/mm, thickness 50 mu m, from the type layer as the protection film, when using the sensitization to cover the membrane, can tear off from the type layer.
In this embodiment, the acrylic resin is added as a solvent, and specifically, may be one or more of a full-acrylic resin, a styrene-acrylic resin, a silicone-acrylic resin, a vinyl acetate-acrylic resin, a fluorine-acrylic resin, or a tertiary acrylic resin, and may be mixed with acrylic resins having different polymerization degrees.
In this embodiment, all use biphenyl type epoxy for the sensitization glue film is more stable, is difficult to the crackle.
Since acrylic resin, biphenyl type epoxy resin, and the like are colorless transparent resins, the use of acrylic resin, bisphenol a type epoxy resin, biphenyl type epoxy resin does not affect the light transmittance of the photosensitive adhesive layer.
In this embodiment, the curing agent is one or a combination of more of diaminodiphenyl sulfone, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride, and after the curing agent is polymerized with the epoxy resin, the polymer formed does not yellow, for example, diaminodiphenyl sulfone does not have free amine, which avoids yellowing caused by direct polymerization of free amine with the epoxy resin, and tetrahydrophthalic anhydride and hexahydrophthalic anhydride do not have amino group, do not generate free amine, and do not have basic group of yellowing, so the photosensitive cover film of this embodiment does not yellow under long-time irradiation of the LED lamp, remains white, and ensures the reflection effect of MiniLED.
In this embodiment, the pigment, the filler and the flame retardant are all white titanium dioxide, which is an important inorganic chemical pigment, the main component is titanium dioxide, the pigment stability is good, and the titanium dioxide is used as the filler and the pigment, so that the finally formed photosensitive adhesive layer has high reflectivity to the LED light.
In the present embodiment, the photoinitiator is one or more of a combination of a photoinitiator TPO, a photoinitiator 184 and a photoinitiator 819; the photoinitiator 819 is used as acylphosphine oxide, and the photoinitiator 819 hardly yellows after curing and under the condition of long-term light radiation, so that the photoinitiators can be used in occasions with strict requirements on yellowing; both the photoinitiator TPO and the photoinitiator 184 have the performance of not easily turning yellow after film forming, so that the photoinitiator selected by the embodiment cannot cause the photosensitive covering film to turn yellow, thereby ensuring the reflection effect of the MiniLED.
Through this embodiment, realize following technological effect: (1) In the FPC process of the MiniLED, the white photosensitive covering film is used for replacing white ink, so that the printing and baking processes of the white ink are reduced, the process efficiency is improved, in addition, the defects that the white ink is easily influenced by the environment, such as impurities and foreign matters caused by the white ink or the environment, are also reduced, and the yield of the MiniLED is improved;
(2) The roughness of the contact surface of the carrier layer of the white photosensitive covering film and the photosensitive adhesive layer is 0.3 mu m, so that the roughness of the release layer is greatly increased, the surface roughness of the photosensitive adhesive layer is also improved in the process of preparing the photosensitive covering film, the carrier layer and the release layer can be removed in the process of manufacturing the FPC and using the photosensitive covering film, the binding force between the photosensitive adhesive layer and the FPC related materials is improved, the defects such as layering and warping of the FPC are avoided, in addition, the roughness of the carrier layer is 0.3 mu m, more diffuse reflection of the whole white photosensitive covering film is realized, and the light of a MiniLED is softer;
(3) The photosensitive adhesive layer of the white photosensitive covering film adopts colorless transparent resin, a non-yellowing curing agent and a non-yellowing photoinitiator, and a certain amount of titanium dioxide is added, so that the titanium dioxide is not yellowed, the white photosensitive covering film is not yellowed on one hand, and the reflectivity is high on the other hand, and the display effect of a MiniLED is better;
(4) Under the irradiation of ultraviolet light, carboxyl of acrylic resin of the photosensitive adhesive layer and free radicals of a photoinitiator are subjected to reaction curing reaction, so that the acrylic resin is completely cured, and the aperture is smaller after the acrylic resin is cured, so that more LED chip openings can be arranged in a unit area of the photosensitive covering film, the LED chip openings are reduced to 50 micrometers, each opening can be provided with one LED chip, and more LED chips can be arranged in the unit area.
Example eight:
the difference from the seventh embodiment is that the roughness of the contact surface of the release layer 3 and the photosensitive adhesive layer 2 is 0.5 μm, and the surface roughness of the calendering roller is 0.5 μm.
The technical solution disclosed in the eighth embodiment has the same components as those in the seventh embodiment, please refer to the description of the seventh embodiment, which will not be repeated herein.
Example nine:
the difference from the seventh embodiment is that the roughness of the contact surface of the release layer 3 and the photosensitive glue layer 2 is 1 μm, and the surface roughness of the calendering roll is 1 μm.
The technical solutions disclosed in the ninth embodiment and the seventh embodiment have the same parts, and please refer to the description of the seventh embodiment, which will not be repeated herein.
Comparative example 1
The difference from the first, second and third embodiments is that the white ink is still used in the first embodiment, rather than the photosensitive cover film, during the FPC process of MiniLED.
Comparative example No. two
The difference from the first embodiment, the second embodiment and the third embodiment is that the FPC photosensitive coverlay for MiniLED of the second embodiment is white, and comprises, from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, carrier layer 1 with from type layer 3 with the contact surface roughness of sensitization glue film 2 is 0.05 mu m, the carrier layer is the PET material, is PET from the type layer.
Comparative example No. three
The differences from the first embodiment, the second embodiment and the third embodiment are that the photosensitive coverlay for the FPC for the MiniLED of the third embodiment is white, and sequentially comprises from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, carrier layer 1 with from type layer 3 and the contact surface roughness of sensitization glue film 2 is 0.08 mu m, the carrier layer is the PET material, is PET from the type layer.
Comparative example No. four
The differences from the first embodiment, the second embodiment and the third embodiment are that the photosensitive coverlay for the FPC for the MiniLED of the fourth embodiment is white, and sequentially comprises from bottom to top: carrier layer 1, sensitization glue film 2 and from type layer 3, carrier layer 1 with from type layer 3 with the contact surface roughness of sensitization glue film 2 is 0.1 mu m, the carrier layer is the PET material, is PET from the type layer.
Through the comparison test of the bonding force between the carrier layer of the FPC photosensitive cover film for the MiniLED and related materials of the FPC, the specific test result is shown in FIG. 5 under the condition that the same FPC base material A (specifically, a polyimide film, the contact surface roughness is 0.1 μm) and copper foil are selected, and as can be seen from the test result of FIG. 5, the bonding force between the photosensitive adhesive layer and the FPC base material A and the copper foil is larger as the roughness of the carrier layer and the release layer is increased, and when the roughness of the carrier layer and the roughness of the release layer are respectively 0.3 μm, 0.5 μm and 1 μm, the bonding force between the photosensitive adhesive layer and the FPC base material A and the copper foil is increased, and the increase value is 0.8N/cm-8.6N/cm; in the aspect of reflectivity, the reflectivity of the photosensitive covering film to light of the LED is increased along with the increase of the roughness of the carrier layer and the release layer, and when the roughness of the carrier layer and the roughness of the release layer are respectively 0.3 mu m, 0.5 mu m and 1 mu m, the reflectivity of the first comparative example, the second comparative example, the third comparative example and the fourth comparative example are increased, and the increase range is 2-5.7%; in terms of yellowing index of 1 year, in the first to ninth examples, the second comparative example, the third comparative example and the fourth comparative example, since the photosensitive adhesive layer adopts acrylic resin, epoxy resin, curing agent and photoinitiator which do not cause yellowing, the yellowing index Δ Yi of the photosensitive covering film in 1 year of use is 0 grade, namely, no yellowing occurs basically, and in the first comparative example, white ink is adopted as the reflecting layer of the LED lamp light, and the yellowing index Δ Yi of the reflecting layer in 1 year of use is 1 grade.

Claims (9)

1. A FPC sensitization covers membrane for MiniLED, its characterized in that, the sensitization covers the membrane and is white, includes from bottom to top in proper order: the photosensitive adhesive comprises a carrier layer, a photosensitive adhesive layer and a release layer, wherein the roughness of the contact surfaces of the carrier layer and the release layer with the photosensitive adhesive layer is 0.3-1 μm, and the roughness of the surface of the photosensitive adhesive layer is 0.3-1 μm;
the formula of the photosensitive adhesive layer comprises, by weight, 40-50 parts of acrylic resin, 10-15 parts of epoxy resin, 3-6 parts of curing agent, 0.5-2 parts of photoinitiator and 35-40 parts of titanium dioxide.
2. The FPC photosensitive coverlay for MiniLED of claim 1, wherein the carrier layer is PET.
3. The FPC photosensitive coverlay for MiniLED of claim 2, wherein the preparation process of the carrier layer or the release layer comprises a calendering process of a calendering roller, a plurality of protrusions are arranged on the surface of the calendering roller, and the surface roughness of the calendering roller is 0.3-1 μm.
4. The FPC photosensitive coverlay for MiniLED of claim 3, wherein the protrusions are spherical and uniformly distributed.
5. The FPC photosensitive coverlay for MiniLED of claim 3, wherein the protrusions are elongated, and the direction of the elongated shape is non-directional.
6. The FPC photosensitive cover film for MiniLED according to claim 3, wherein said protrusions are a combination of long strips and balls.
7. The FPC photosensitive coverlay for MiniLED of claim 1-6, wherein the carrier layer has a light transmittance of greater than 95% and a thickness of 15 μm-75 μm.
8. The FPC photosensitive coverlay for MiniLED of claim 1-6, wherein the release layer is made of PET or PE, the release force between the release layer and the photosensitive adhesive layer is 10g/mm-100g/mm, and the thickness is 15 μm-75 μm.
9. The FPC photosensitive coverlay for MiniLED of claim 8, wherein the curing agent is one or more combination of diaminodiphenyl sulfone, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, and the photoinitiator is one or more combination of photoinitiator TPO, photoinitiator 184 and photoinitiator 819.
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JP3522127B2 (en) * 1998-11-17 2004-04-26 日立化成工業株式会社 Photosensitive film and lamination method thereof
JP5485083B2 (en) * 2010-08-31 2014-05-07 日東電工株式会社 Thermosetting adhesive tape or sheet
TWM543773U (en) * 2017-01-26 2017-06-21 長興材料工業股份有限公司 Photosensitive dry film
TWI634003B (en) * 2017-01-26 2018-09-01 長興材料工業股份有限公司 Photosensitive dry film and uses of the same
CN107172804B (en) * 2017-07-11 2023-12-26 昆山倬跃蓝天电子科技有限公司 Photosensitive covering film and product
CN107360667A (en) * 2017-07-11 2017-11-17 苏州城邦达力材料科技有限公司 A kind of photosensitive cover layer and preparation method thereof
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CN111650811B (en) * 2020-06-18 2024-01-26 上海孚赛特新材料股份有限公司 White photosensitive film and preparation method and application thereof

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