Insulating heat-conducting glue, double-sided tape containing same, preparation method and application of insulating heat-conducting glue

Abstract

The invention provides insulating heat-conducting glue, an adhesive tape, a preparation method and application, and relates to the field of electronic materials. The adhesive tape comprises the following raw materials in parts by weight: 22-32 parts of methyl methacrylate, 60-70 parts of butyl acrylate, 0.8-1 part of azodiisobutyronitrile, 25-51 parts of boron nitride heat-conducting filler and 4-10 parts of acrylic acid, and the preparation method of the adhesive tape comprises the following steps: adding the heat-conducting filler into toluene, ultrasonically stirring for 10-20 minutes, and uniformly dispersing; and adding methyl methacrylate, butyl acrylate, acrylic acid and azodiisobutyronitrile, stirring at 60-90 DEG C for 5-10 minutes, reacting at 60-90 DEG C for 1-2 hours, keeping the temperature for 1-2 hours, and filtering to obtain the insulating heat-conducting glue. S2, coating the surface of a base material with the insulating heat-conducting glue in the step S2, and drying at 100-120 DEG C for 10-15 minutes to obtain a prefabricated adhesive tape; and carrying out hot pressing on the prefabricated adhesive tape at 120-150 DEG C and 3-5 MPa for 1-2 minutes to obtain the insulating heat-conducting double-sided adhesive tape. The insulating heat-conducting double-sided adhesive tape has excellent heat conductivity and insulativity, can be applied to an LED lamp backlight module, and improves the heat dissipation effect.

Description

Technical Field

[0001] The invention relates to the field of electronic materials, and in particular to an insulating thermally conductive adhesive, a double-sided adhesive tape containing the insulating thermally conductive adhesive, a preparation method and applications thereof. Background Art

[0002] Thermally conductive double-sided tape is a material with thermal conductivity and viscosity. It is widely used in the bonding and thermal conduction of heat sinks, processors, chips and other components of electronic products, the thermal conduction and fixation of LED lights, etc.

[0003] Patents CN102559089A and CN107057600A disclose a water-based acrylic thermally conductive double-sided tape and a method for making the same. The tape consists of an upper pressure-sensitive adhesive layer, a glass fiber fabric layer and a lower pressure-sensitive adhesive layer. The thermal conductivity reaches 1.18W / m·k and the peel strength reaches 26N / 25mm. The thermally conductive layer consists of a water-based high-temperature resistant acrylic pressure-sensitive adhesive, thermally conductive filler ceramic powder, aluminum nitride, boron nitride, dispersant and coupling agent. CN118271996A discloses a high thermally conductive double-sided tape for LED bonding, which consists of a release layer, a polyester film, and a double-sided acrylic thermally conductive adhesive layer. The thermally conductive adhesive layer includes an acrylic ester glue, a curing agent and a modified AlN thermally conductive powder. CN218232273U has developed an insulating thermally conductive tape, whose structure from bottom to top is a release film layer, a first thermally conductive adhesive layer, a copper foil layer, a second thermally conductive adhesive layer, a graphene film layer, and a thermally conductive silicone layer. Although there are copper foil and graphene conductive layers in the middle, the thermally conductive silicone layer can insulate and prevent leakage. CN117343654A discloses a thermally tackified thermally conductive tape, which is composed of a polyimide film, a thermally tackified thermally conductive adhesive layer and a release layer. The thermally tackified thermally conductive adhesive layer is composed of a composition composed of a tackifying resin, an acrylate active monomer, butyl rubber and a thermally conductive filler, a leveling agent, a coupling agent, an adhesive, a curing agent, a accelerator and a toughening agent, wherein the thermally conductive filler is selected from one or more of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, and silicon carbide. The resulting tape has a peeling force of 13.6-18.5N / 25mm and a thermal conductivity of 12-16W / m·K.

[0004] CN114213982A discloses a substrate-free thermally conductive adhesive tape, which is composed of a first release layer, an adhesive layer, and a second release layer, wherein the adhesive layer comprises rosin-based epoxy acrylate prepolymer, isobornyl acrylate, 3-(1,1-difluoroallyl)quinoxaline-2-ol, bis(vinylsulfone)methane, methacrylic acid, quaternary ammonium salt-based calix[3]carbazole, isocyanate-modified thermally conductive filler, a catalyst, an initiator, and an organic solvent, wherein the thermally conductive filler is a mixture of nano-boronated silicon, nano-alumina, silicon micropowder, and graphene quantum dots, and the thermal conductivity of the obtained tape is about 1.5 W / m·K. CN103013378B discloses a nano-scale thermally conductive tape, which is composed of a high-temperature resistant polyacrylic acid adhesive, α-Al2O3, Al(OH)3, polyester cloth or glass fiber, and a reactant. The invention utilizes the mixing of nano-scale aluminum oxide and aluminum hydroxide and the densest crystal stacking to achieve a filling amount of more than 92%, and enables the material properties to reach a thermal conductivity of 3.5W / m·K and a viscosity of 2.0Kgf / 25mm. CN215975624U discloses a new multifunctional thermally conductive tape, including a tensile and anti-fault layer, an insulating layer, a waterproof layer, a heat-insulating layer, a fire-resistant layer, a heat-conducting acrylic adhesive layer, and an adhesive layer. CN113667429B has developed a UV-curable thermally conductive tape, which is composed of a photocurable resin, polyacrylate, thermally conductive filler (aluminum oxide, aluminum hydroxide, hexagonal boron nitride, silicon carbide), acrylic acid ester active monomer, photoinitiator, coupling agent, and leveling agent. The thermal conductivity of the tape is 1.5W / mK. After 5-30s of light reaction, the adhesive is cured, and the electronic components can be packaged. CN117820973A discloses a new type of fast heat dissipation thermally conductive double-sided tape, which is composed of a polyester film, a double-sided adhesive layer, a protective coating, and a release layer. The thermally conductive filler is ceramic thermally conductive, and the thermal conductivity of the tape is 0.4-1.2W / m·K. CN117210161A discloses a thermally conductive tape consisting of a substrate, a thermally conductive coating and a thermally conductive glue layer, wherein the thermally conductive coating consists of a thermally conductive filler, a resin, a curing agent and a flame retardant, and the glue layer consists of an acrylic glue, a thermally conductive filler and a curing agent, wherein the thermally conductive filler is one or more of aluminum oxide, boron nitride, magnesium oxide, zinc oxide, aluminum nitride and silicon carbide, and the thermal conductivity of the obtained tape is greater than 0.30 W / (m·K), and the initial viscosity is greater than 23 N / 25 mm.

[0005] There are two major problems with the existing technology. First, the thermal conductive tape is prepared with graphene, carbon nanotubes, etc. as thermal conductive fillers, which can achieve a very high thermal conductivity, even reaching more than 20W / m·K (CN116814180A, CN104178048B), but this thermal conductive tape often has no insulation performance, and it is difficult to prevent short circuits and electrical failures caused by current leakage in electronic components. Second, the thermal conductive tape is prepared with insulating materials such as boron nitride, aluminum nitride, and aluminum oxide as thermal conductive fillers. The thermal conductivity is relatively low, usually <1W / m·K, and too much thermal conductive powder will affect the viscosity of the tape. In addition, there is no relevant patent research on how to use the thermally conductive double-sided insulating tape in the backlight module. Summary of the invention

[0006] The invention aims to provide an insulating heat-conducting glue, which has a thermal conductivity of 1.17-1.65 W / (m·K) and has excellent thermal conductivity and insulation.

[0007] Another object of the present invention is to provide an insulating thermally conductive double-sided tape, which has a thermal conductivity of 1.17-1.65 W / (m·K) and a tape peeling force of 24.31-25.43 N / 25 mm, and has excellent thermal conductivity and insulation.

[0008] The third object of the present invention is to provide a method for preparing an insulating thermally conductive double-sided adhesive tape, which comprises coating thermally conductive glue on the surface of a substrate, drying and hot pressing, and the process is simple.

[0009] The fourth purpose of the present invention is to provide an application of an insulating thermally conductive glue or double-sided tape. By applying the glue or tape to the LED backlight module, the heat generated by the LED lamp board, LED light source and chip during operation can be evenly diffused to the backlight back panel made of a high thermal conductivity alloy material, thereby extending the service life of the LED lamp.

[0010] The present invention solves the technical problem by adopting the following technical solutions.

[0011] On the one hand, an embodiment of the present invention provides an insulating thermally conductive adhesive, which includes the following raw materials in parts by weight:

[0012] 22-32 parts of methyl methacrylate, 60-70 parts of butyl acrylate, 0.8-1 parts of azobisisobutyronitrile, 25-51 parts of boron nitride thermal conductive filler and 4-10 parts of acrylic acid.

[0013] In some embodiments of the present invention, the boron nitride thermal conductive filler includes, by weight, boron nitride powder of the following particle sizes: 0-10 parts of 2 μm boron nitride powder, 0-45 parts of 4 μm boron nitride powder, 0-45 parts of 8 μm boron nitride powder, 0-25 parts of 12 μm boron nitride powder, and 0-25 parts of 20 μm boron nitride powder.

[0014] BN powder (boron nitride powder) of different particle sizes is used as a thermal conductive filler. In the glue, the boron nitride powder of different particle sizes is cross-linked with methyl methacrylate, butyl acrylate and acrylic acid to form a denser network structure. The large-sized BN can cooperate with methyl methacrylate, butyl acrylate and acrylic acid to wrap the small-sized BN, thereby forming a continuous and dense network thermal conductive structure in both the horizontal and vertical directions, forming a continuous thermal conductive path. When in use, heat can be timely conducted through the BN thermal conductive filler in the thermal conductive glue and the continuous thermal conductive path formed by BN thermal conductive fillers of different particle sizes; compared with thermal conductive fillers of a single particle size, it cannot form a continuous thermal conductive path in the glue. When conducting heat, it will accumulate in the polymer glue due to the breakage of the thermal conductive path, resulting in a low thermal conductivity coefficient.

[0015] In some embodiments of the present invention, the following raw materials are included by weight: 24 parts of methyl methacrylate, 70 parts of butyl acrylate, 1 part of azobisisobutyronitrile, 6 parts of acrylic acid, 20 parts of 4μm boron nitride powder, and 25 parts of 8μm boron nitride powder. The thermal conductivity of the thermally conductive adhesive is 1.65W / (m·K), and the thermally conductive double-sided tape made with the adhesive has a tape peeling force of 24.86N / 25mm.

[0016] On the other hand, an embodiment of the present invention provides an insulating thermally conductive double-sided tape, comprising an upper protective film, an upper glue layer, a substrate, a lower glue layer and a lower protective film arranged in sequence from top to bottom, and the upper glue layer and the lower glue layer are both made of the above-mentioned insulating thermally conductive glue.

[0017] In some embodiments of the present invention, the substrate is one of a polyimide film, a polyethylene terephthalate film and a glass fiber film.

[0018] In some embodiments of the present invention, the upper protective film and the lower protective film are both anti-adhesion heavy-duty or light-duty release films, specifically, one of fluorine release films or white glassine release papers.

[0019] In a third aspect, an embodiment of the present invention provides a method for preparing an insulating thermally conductive double-sided tape, comprising the following steps:

[0020] S1, adding thermal conductive filler to toluene, stirring ultrasonically for 5-20 minutes, and dispersing evenly;

[0021] S2, adding methyl methacrylate, butyl acrylate, acrylic acid and azobisisobutyronitrile, stirring at 60-90° C. for 5-10 min, reacting at 60-90° C. for 1-2 h, then keeping warm for 1-2 h, filtering, and obtaining the insulating thermal conductive glue;

[0022] S3, coating the insulating thermal conductive glue of step S2 on the surface of the substrate, and drying at 100-120° C. for 10-15 minutes to obtain a prefabricated tape;

[0023] S4, hot pressing the prefabricated tape at 120-150° C. and 3-5 MPa for 1-2 min to obtain the insulating and thermally conductive double-sided tape.

[0024] In some embodiments of the present invention, in step S2, the reaction is carried out at 75° C. for 2 hours, then kept at 80° C. for 1 hour, and filtered through a 300-mesh filter.

[0025] In some embodiments of the present invention, in step S3, drying is performed at 120° C. for 10 minutes.

[0026] In some embodiments of the present invention, in step S4, hot pressing is performed at 150° C. and 3 MPa for 1 min.

[0027] In a fourth aspect, an embodiment of the present invention provides an application of an insulating thermally conductive glue and / or an insulating thermally conductive double-sided tape on an LED backlight module.

[0028] In some embodiments of the present invention, an LED backlight module includes a backlight back panel, a second thermally conductive double-sided tape, a reflective plate, a first thermally conductive double-sided tape, an LED light board, a first thermally conductive glue, a diffusion plate, a second thermally conductive glue, a brightness enhancement film, a dual brightness enhancement film, an upper diffusion film, a glue frame, and an FPC flexible circuit board connected to the LED light board, and the FPC flexible circuit board is adhered to the backlight back panel via a third thermally conductive double-sided tape.

[0029] The various parts of the backlight module are connected to each other in a fitted form. The plastic frame is used to fix and protect the various layers of materials in the backlight module, and also plays a role in shading. The front and back sides of the upper diffusion film and the diffusion plate are coated with nanoparticles that scatter light on their surfaces, so that the light can be evenly scattered when passing through the diffusion film. The dual brightness enhancement film (DBEF) is a multi-layer optical film that can reflect the "S light" blocked by the liquid crystal panel, and recycle and re-project the "P light" and "S light", thereby recycling 40% of the "S light" and improving the efficiency of light utilization by polarizing the backlight. The brightness enhancement film (BEF) uses its internal micro-prism structure to continuously recycle the light under the action of the prism structure, thereby achieving the effect of axial brightness enhancement. The LED light board is a white light LED surface light source, which is responsible for the generation and emission of backlight and is driven by the backlight driver chip on the FPC flexible circuit board. The reflector is used to reflect the leakage light of the LED light board back to the light output direction of the backlight module, thereby improving the utilization rate of light. The backlight backplane is a die-cast aluminum alloy or magnesium alloy structure, which provides structural support for the entire backlight module. The thermal conductive glue or thermal conductive double-sided tape of the present invention is set at 5 locations in the entire LED backlight module. Thermal conductive glue is used to bond between the brightness enhancement film and the diffuser plate, and between the diffuser plate and the LED light board, so that heat can be dissipated from all sides of the film material. Thermal conductive double-sided tape is set under the LED light board, under the FPC flexible circuit board, and above the backlight backplane, so that the heat of the LED light source and chip on the LED light board and the FPC flexible circuit board can be evenly diffused to the backlight backplane made of a high thermal conductivity alloy material during operation. In addition to heat dissipation, the thermal conductive double-sided tape is also used for the bonding and fixation of various components.

[0030] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0031] The insulating thermally conductive glue provided by the present invention uses boron nitride as a thermally conductive filler, so that the glue has excellent thermal conductivity and insulation, and the thermal conductivity coefficient is 1.17-1.65W / (m·K). Compared with the existing boron nitride thermally conductive glue, the thermal conductivity coefficient is significantly improved, and the thermal conductive effect is excellent.

[0032] The insulating thermally conductive double-sided tape provided by the present invention uses insulating thermally conductive glue as a main thermally conductive material and is coated on the surface of a substrate. The thermal conductivity of the double-sided tape is 1.17-1.65 W / (m·K), the tape peeling force is 24.31-25.43 N / 25 mm, the viscosity is moderate, and the application range is wide.

[0033] The glue and double-sided tape provided by the present invention are applied to the LED backlight module, which can play an excellent insulation and heat conduction effect, so that the heat generated by the LED lamp board, LED light source and chip during operation can be evenly diffused to the backlight back panel made of alloy material with high thermal conductivity, thereby extending the service life of the LED lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 A schematic diagram of the structure of the insulating and thermally conductive double-sided adhesive tape provided in an embodiment of the present invention;

[0036] Figure 2 A process diagram for preparing the insulating and thermally conductive double-sided adhesive tape provided in Example 1 of the present invention;

[0037] Figure 3 This is a schematic diagram of an explosion in an LED backlight module;

[0038] Figure 4 The effect of BN powder with different particle sizes on thermal conductivity;

[0039] Figure 5 The effect of BN powder with different particle sizes on the peeling force;

[0040] Figure 6 The influence of different input ratios of BN thermal conductive filler on thermal conductivity;

[0041] Figure 7 The effect of different input ratios of BN thermal conductive filler on the peeling force;

[0042] Figure 8 The influence of different types of thermal conductive fillers on thermal conductivity;

[0043] Fig. 9 The effect of different types of thermal conductive fillers on the peeling force;

[0044] Icon: 1-upper protective film, 2-upper glue layer, 3-substrate, 4-lower glue layer, 5-lower protective film, 7-glue frame, 8-upper diffusion film, 9-dual brightness enhancement film, 10-brightness enhancement film, 11-second thermal conductive glue, 12-diffusion plate, 13-first thermal conductive glue, 14-LED light board, 15-first thermal conductive double-sided tape, 16-reflection plate, 17-second thermal conductive double-sided tape, 18-backlight backplane, 19-FPC flexible circuit board, 20-third thermal conductive double-sided tape. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0046] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0047] On the one hand, an embodiment of the present invention provides an insulating thermally conductive adhesive, which includes the following raw materials in parts by weight:

[0048] 22-32 parts of methyl methacrylate, 60-70 parts of butyl acrylate, 0.8-1 parts of azobisisobutyronitrile, 25-51 parts of boron nitride thermal conductive filler and 4-10 parts of acrylic acid.

[0049] In some embodiments of the present invention, the boron nitride thermal conductive filler includes, by weight, boron nitride powder of the following particle sizes: 0-10 parts of 2 μm boron nitride powder, 0-45 parts of 4 μm boron nitride powder, 0-45 parts of 8 μm boron nitride powder, 0-25 parts of 12 μm boron nitride powder, and 0-25 parts of 20 μm boron nitride powder.

[0050] BN powder (boron nitride powder) of different particle sizes is used as a thermal conductive filler. In the glue, the boron nitride powder of different particle sizes is cross-linked with methyl methacrylate, butyl acrylate and acrylic acid to form a denser network structure. The large-sized BN can cooperate with methyl methacrylate, butyl acrylate and acrylic acid to wrap the small-sized BN, thereby forming a continuous and dense network thermal conductive structure in both the horizontal and vertical directions, forming a continuous thermal conductive path. When in use, heat can be timely conducted through the BN thermal conductive filler in the thermal conductive glue and the continuous thermal conductive path formed by BN thermal conductive fillers of different particle sizes; compared with thermal conductive fillers of a single particle size, it cannot form a continuous thermal conductive path in the glue. When conducting heat, it will accumulate in the polymer glue due to the breakage of the thermal conductive path, resulting in a low thermal conductivity coefficient.

[0051] On the other hand, an embodiment of the present invention provides an insulating thermally conductive double-sided tape, comprising an upper protective film 1, an upper glue layer 2, a substrate 3, a lower glue layer 4 and a lower protective film 5 arranged in sequence from top to bottom, and the upper glue layer 2 and the lower glue layer 4 are both made of the above-mentioned insulating thermally conductive glue.

[0052] In some embodiments of the present invention, the substrate is one of a polyimide film, a polyethylene terephthalate film and a glass fiber film.

[0053] In some embodiments of the present invention, the upper protective film and the lower protective film are both anti-adhesion heavy-duty or light-duty release films, specifically, one of fluorine release films or white glassine release papers.

[0054] In a third aspect, an embodiment of the present invention provides a method for preparing an insulating thermally conductive double-sided tape, comprising the following steps:

[0055] S1, adding thermal conductive filler to toluene, stirring ultrasonically for 5-20 minutes, and dispersing evenly;

[0056] S2, adding methyl methacrylate, butyl acrylate, acrylic acid and azobisisobutyronitrile, stirring at 60-90° C. for 5-10 min, reacting at 60-90° C. for 1-2 h, then keeping warm for 1-2 h, filtering, and obtaining the insulating thermal conductive glue;

[0057] S3, coating the insulating thermal conductive glue of step S2 on the surface of the substrate, and drying at 100-120° C. for 10-15 minutes to obtain a prefabricated tape;

[0058] S4, hot pressing the prefabricated tape at 120-150° C. and 3-5 MPa for 1-2 min to obtain the insulating and thermally conductive double-sided tape.

[0059] In a fourth aspect, an embodiment of the present invention provides an application of an insulating thermally conductive glue and / or an insulating thermally conductive double-sided tape on an LED backlight module.

[0060] In some embodiments of the present invention, an LED backlight module includes a backlight back panel 18, a second thermally conductive double-sided tape 17, a reflective plate 16, a first thermally conductive double-sided tape 15, an LED light board 14, a first thermally conductive glue 13, a diffusion plate 12, a second thermally conductive glue 11, a brightness enhancement film 10, a dual brightness enhancement film 9, an upper diffusion film 8, a glue frame 7, and an FPC flexible circuit board 19 connected to the LED light board 14, and the FPC flexible circuit board 19 is adhered to the backlight back panel 18 through a third thermally conductive double-sided tape 20.

[0061] The various parts of the backlight module are connected to each other in a fitted form. The rubber frame 7 is used to fix and protect the various layers of materials in the backlight module, and also plays a role in shading. The front and back surfaces of the upper diffusion film 8 and the diffusion plate 12 are coated with nanoparticles that scatter light on their surfaces, so that the light can be evenly scattered when passing through the diffusion film. The dual brightness enhancement film (DBEF) 9 is a multi-layer optical film that can reflect the "S light" blocked by the liquid crystal panel, and recycle and re-project the "P light" and "S light", thereby recycling 40% of the "S light" and at the same time improving the efficiency of light utilization by polarizing the backlight. The brightness enhancement film (BEF) 10 uses its internal micro-prism structure to continuously recycle the light under the action of the prism structure, thereby achieving the effect of axial brightness enhancement. The LED light board 14 is a white light LED surface light source, which is responsible for the generation and emission of the backlight and is driven by the backlight driver chip on the FPC flexible circuit board 19. The reflector 16 is used to reflect the leaked light of the LED light board 14 back to the light emitting direction of the backlight module, thereby improving the utilization rate of light. The backlight back panel 18 is a die-cast aluminum alloy or magnesium alloy structure, which provides structural support for the entire backlight module. The thermal conductive glue or thermal conductive double-sided tape of the present invention is arranged at 5 locations in the entire LED backlight module. Thermal conductive glue is used to bond the surrounding positions between the brightness enhancement film 10 and the diffuser plate 12, and between the diffuser plate 12 and the LED light board 14, so that heat can be dissipated from all around the film material. Thermal conductive double-sided tape is arranged under the LED light board 14, under the FPC flexible circuit board 19, and above the backlight back panel 18, so that the heat dissipation of the LED light source and chip on the LED light board 14 and the FPC flexible circuit board 19 during operation can be evenly diffused to the backlight back panel 18 made of an alloy material with high thermal conductivity. In addition to heat dissipation, the thermal conductive double-sided tape is also used for bonding and fixing between various components.

[0062] The sources of the raw materials used in the examples and comparative examples are shown in Table 1:

[0063] Table 1 Source of raw materials

[0064]

[0065] Example 1

[0066] Prepare insulating thermal conductive glue and double-sided tape according to the following ratio:

[0067] 24 parts of methyl methacrylate, 70 parts of butyl acrylate, 6 parts of acrylic acid, 1 part of azobisisobutyronitrile (AIBN), 20 parts of BN thermal conductive filler with a particle size of 4 μm, 25 parts of BN thermal conductive filler with a particle size of 8 μm, and 100 parts of toluene.

[0068] Weigh the thermal conductive filler according to the mass ratio, stir it with toluene ultrasonically for 5 minutes to disperse it evenly, then add methyl methacrylate, butyl acrylate, acrylic acid and AIBN, heat and stir it at 75℃ for 5 minutes, react at 75℃ for 2 hours, then keep it at 80℃ for 1 hour, filter it with a 300-mesh filter to obtain thermal conductive glue. Coat the thermal conductive glue on both sides of the PI film, dry it at 120℃ for 10 minutes, and finally hot press it at 150℃ and 3MPa for 1 minute to obtain a thermal conductive double-sided tape. After testing, the thermal conductivity of the thermal conductive tape is 1.65W / (m·K), and the tape peeling force is 24.86N / 25mm.

[0069] The obtained thermally conductive glue and thermally conductive double-sided tape are used for making LED backlight modules.

[0070] Example 2

[0071] Prepare insulating thermal conductive glue and double-sided tape according to the following ratio:

[0072] 32 parts of methyl methacrylate, 60 parts of butyl acrylate, 10 parts of acrylic acid, 0.8 parts of azobisisobutyronitrile (AIBN), 25 parts of BN thermal conductive filler with a particle size of 4 μm, 25 parts of BN thermal conductive filler with a particle size of 8 μm, and 100 parts of toluene.

[0073] The preparation method of the thermal conductive glue and the thermal conductive double-sided tape is the same as that of Example 1.

[0074] Example 3

[0075] Prepare insulating thermal conductive glue and double-sided tape according to the following ratio:

[0076] 22 parts of methyl methacrylate, 65 parts of butyl acrylate, 8 parts of acrylic acid, 0.9 parts of azobisisobutyronitrile (AIBN), 2 parts of 2μm boron nitride powder, 15 parts of BN thermal conductive filler with a particle size of 4μm, 10 parts of BN thermal conductive filler with a particle size of 8μm, 10 parts of 12μm boron nitride powder, 5 parts of 20μm boron nitride powder, and 100 parts of toluene.

[0077] The preparation method of the thermal conductive glue and the thermal conductive double-sided tape is the same as that of Example 1.

[0078] Example 4

[0079] Prepare insulating thermal conductive glue and double-sided tape according to the following ratio:

[0080] 24 parts of methyl methacrylate, 70 parts of butyl acrylate, 6 parts of acrylic acid, 1 part of azobisisobutyronitrile (AIBN), 5 parts of 2μm boron nitride powder, 15 parts of BN thermal conductive filler with a particle size of 4μm, 15 parts of BN thermal conductive filler with a particle size of 8μm, 5 parts of 12μm boron nitride powder, 5 parts of 20μm boron nitride powder, and 100 parts of toluene.

[0081] The preparation method of the thermal conductive glue and the thermal conductive double-sided tape is the same as that of Example 1.

[0082] Example 5

[0083] Prepare insulating thermal conductive glue and double-sided tape according to the following ratio:

[0084] 24 parts of methyl methacrylate, 70 parts of butyl acrylate, 6 parts of acrylic acid, 1 part of azobisisobutyronitrile (AIBN), 2 parts of 2μm boron nitride powder, 10 parts of BN thermal conductive filler with a particle size of 4μm, 10 parts of BN thermal conductive filler with a particle size of 8μm, 2 parts of 12μm boron nitride powder, 1 part of 20μm boron nitride powder, and 100 parts of toluene.

[0085] The preparation method of the thermal conductive glue and the thermal conductive double-sided tape is the same as that of Example 1.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that a BN thermal conductive filler with a single particle size is used to prepare the thermally conductive glue and the thermally conductive double-sided tape. Specifically, BN powders of 2 μm, 4 μm, 8 μm, 12 μm, and 20 μm, and a BN suspension with a particle size of 5 μm are selected as fillers. The remaining raw material ratios and preparation methods are the same as those in Example 1, and 6 types of thermally conductive double-sided tapes are obtained.

[0088] Comparative Example 2

[0089] The difference from Example 1 is that different proportions of BN thermal conductive filler are added to prepare thermal conductive glue and thermal conductive double-sided tape. The proportions of each raw material are shown in Table 2, and the preparation method of thermal conductive glue and thermal conductive double-sided tape is the same as that of Example 1.

[0090] Table 2 Raw material ratio

[0091] A B C D E F G H J K Methyl methacrylate(g) 24 24 24 24 24 24 24 24 24 24 Butyl acrylate(g) 70 70 70 70 70 70 70 70 70 70 Acrylic acid(g) 6 6 6 6 6 6 6 6 6 6 Azobisisobutyronitrile (g) 1 1 1 1 1 1 1 1 1 1 Thermally conductive filler(g) 5.05 10.1 15.15 20.2 25.25 30.3 35.35 40.4 45.45 50.5 Thermal conductive filler ratio (%) 5 10 15 20 25 30 35 40 45 50

[0092] in,

[0093]

[0094] The thermal conductive filler is a mixture of 4 μm BN powder and 8 μm BN powder in a mass ratio of 4:5.

[0095] Comparative Example 3

[0096] Based on the raw material ratio provided in Example 1, equal amounts of AlN powder, silicon carbide powder, Al2O3 powder, multi-walled carbon nanotubes, carbon powder, and graphene are used as thermal conductive fillers to replace the BN powder in Example 1. The preparation method of the thermal conductive glue and the thermal conductive double-sided tape is the same as that in Example 1.

[0097] Experimental example

[0098] The thermal conductivity and peeling force of the thermally conductive double-sided tapes prepared in Examples 1-5 and Comparative Examples 1-3 were tested by using a vertical thermal conductivity meter according to the ASTM D5470 standard test method and a viscosity tester according to the GB / T2792-2014 standard test method for 180° peeling force. The thermal conductivity test step was to cut a 25mm×25mm sample for testing, and wipe the upper and lower surfaces with alcohol, apply thermal conductive silicone grease to the hot end and the cold end, press the heating end and the cooling end together, set the pressure to 40psi, the temperature to 80°C, and the time to 20min. After the test was completed, read and record the data. The viscosity test step was to horizontally attach a test sample of 300mm×25mm to a steel plate, roll back and forth three times with 2±0.05kg (one time for each back and forth), roll at a speed of 300mm / min, and let stand for 20min, then use a peeling device to perform a 180° peeling test at a speed of 300±10mm / min, and record the read value. The results are shown in Table 3 and Figure 4-9 shown.

[0099] Table 3 Thermally conductive tape properties of Examples 1-5

[0100]

[0101] from Figure 4 and 5 It can be concluded that BN powder thermal conductive fillers of different particle sizes have little effect on the thermal conductivity of the tape, but the thermal conductivity of the tape obtained by BN suspension is not as good as the tape obtained by using BN powder. If the particle size of BN is too large (≥12μm) or too small (≤2μm), the viscosity of the thermal conductive tape will be significantly reduced. When the particle size of BN powder thermal conductive filler is 4-8μm (single particle size), the viscosity and thermal conductivity of the thermal conductive tape can be guaranteed, the thermal conductivity coefficient is 1.17-1.33W / (m·K), and the tape peeling force is 24.31-25.43N / 25mm. Figure 4 and Examples 1-5, Figure 6 The comparison shows that the thermal conductivity of the tape obtained by using mixed particle size thermal conductive filler is better than that of the tape obtained by using single particle size thermal conductive filler.

[0102] from Figure 6 and 7 It can be concluded that with the increase of the proportion of BN thermal conductive filler (mixed particle size of 4 and 8 μm, mass ratio 4:5), the thermal conductivity of the thermal conductive tape gradually increases, but the viscosity gradually decreases. The optimal BN thermal conductive filler proportion is about 40-45%, and the corresponding thermal conductivity is 1.48-1.65W / (m·K), and the tape peeling force is 20.5-24.5N / 25mm.

[0103] from Figure 8 and 9 It can be concluded that each thermally conductive filler has little effect on the viscosity of the tape, and the tape peeling force is around 22-25N / 25mm. In terms of thermal conductivity, AlN and BN powder thermal conductive fillers have little effect on the thermal conductivity of the tape, and the thermal conductivity of silicon carbide and Al2O3 powder as thermal conductive fillers is not as good as BN powder. Although the thermal conductivity coefficient of the thermally conductive double-sided tape obtained when using multi-walled carbon nanotubes, carbon powder, graphene and other carbon-based materials as thermally conductive fillers is relatively high (>10W / (m·K)), but because carbon-based materials also have conductive properties, they cannot be insulated in backlight module applications. In actual applications, the current on the LED light board and the flexible circuit board will be conducted through the conductive carbon-based materials on the thermally conductive double-sided tape, which may cause short circuits and electrical failures due to current leakage, and will also cause electrostatic interference and safety hazards.

[0104] In summary, the thermally conductive glue and thermally conductive tape provided in the embodiments of the present invention have excellent thermal conductivity and insulation properties and can be used for bonding and heat dissipation of LED backlight modules.

[0105] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. An insulating thermally conductive glue, characterized in that: The following raw materials are included by weight: 22-32 parts of methyl methacrylate, 60-70 parts of butyl acrylate, 0.8-1 parts of azobisisobutyronitrile, 25-51 parts of boron nitride thermal conductive filler and 4-10 parts of acrylic acid.

2. The insulating thermally conductive glue according to claim 1, characterized in that: The boron nitride thermal conductive filler includes boron nitride powders of the following particle sizes by weight: 0-10 parts of 2 μm boron nitride powder, 0-45 parts of 4 μm boron nitride powder, 0-45 parts of 8 μm boron nitride powder, 0-25 parts of 12 μm boron nitride powder, and 0-25 parts of 20 μm boron nitride powder.

3. The insulating thermally conductive glue according to claim 2, characterized in that: The following raw materials are included by weight: 24 parts of methyl methacrylate, 70 parts of butyl acrylate, 1 part of azobisisobutyronitrile, 6 parts of acrylic acid, 20 parts of 4μm boron nitride powder, and 25 parts of 8μm boron nitride powder.

4. An insulating thermally conductive double-sided tape, characterized in that: It comprises an upper protective film, an upper glue layer, a substrate, a lower glue layer and a lower protective film which are arranged in sequence from top to bottom, and the upper glue layer and the lower glue layer are both made of the insulating thermal conductive glue according to any one of claims 1-3.

5. The insulating and thermally conductive double-sided tape according to claim 4, characterized in that: The substrate is one of a polyimide film, a polyethylene terephthalate film and a glass fiber film.

6. A method for preparing the insulating thermally conductive double-sided tape as claimed in claim 4, characterized in that: The following steps are involved: S1, adding boron nitride thermal conductive filler to toluene, stirring ultrasonically for 5-20 minutes, and dispersing evenly; S2, adding methyl methacrylate, butyl acrylate, acrylic acid and azobisisobutyronitrile, stirring at 60-90° C. for 5-10 min, reacting at 60-90° C. for 1-2 h, then keeping warm for 1-2 h, filtering, and obtaining the insulating thermal conductive glue; S3, coating the insulating thermal conductive glue of step S2 on the surface of the substrate, and drying at 100-120° C. for 10-15 minutes to obtain a prefabricated tape; S4, hot pressing the prefabricated tape at 120-150° C. and 3-5 MPa for 1-2 min to obtain the insulating and thermally conductive double-sided tape.

7. The method for preparing the insulating thermally conductive double-sided tape according to claim 6, characterized in that: In the step S2, the reaction is carried out at 75° C. for 2 hours, and then kept at 80° C. for 1 hour, and filtered through a 300-mesh filter.

8. The method for preparing the insulating thermally conductive double-sided tape according to claim 6, characterized in that: In the step S3, drying is performed at 120° C. for 10 minutes.

9. The method for preparing the insulating thermally conductive double-sided tape according to claim 6, characterized in that: In the step S4, hot pressing is performed at 150° C. and 3 MPa for 1 minute.

10. Use of the insulating thermally conductive glue according to any one of claims 1 to 3 and / or the insulating thermally conductive double-sided adhesive tape according to any one of claims 4 to 9 in an LED backlight module.

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