Heat-conducting COB epoxy adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of epoxy resin adhesives, and particularly relates to a heat-conducting COB epoxy adhesive and a preparation method thereof. The flame-retardant coating is prepared from the following components in parts by weight: 30 to 40 parts of bisphenol F862 epoxy resin, 2 to 5 parts of ethylene glycol diglycidyl ether, 40 to 60 parts of aluminum nitride, 1 to 5 parts of antimony oxide, 0.5 to 2 parts of organic silicon defoaming agent, 0.01 to 0.1 part of ultramarine blue dye, 2 to 5 parts of fumed silica, 5 to 10 parts of methyl nadic anhydride and 0.5 to 2 parts of benzyl dimethylamine. According to the heat-conducting COB epoxy adhesive and the preparation method thereof, a step-by-step stirring mode is adopted, firstly, bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether are premixed, then an aluminum nitride raw material is added step by step, and different stirring speeds and time are set, so that all the raw materials are fully contacted and dispersed, and the mixing uniformity is improved; therefore, the phenomenon of material agglomeration caused by adding excessive filler at one time is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of epoxy adhesive, and particularly relates to a heat-conducting COB epoxy adhesive and a preparation method thereof. BACKGROUND

[0002] COB is also called chip on board packaging, that is, a semiconductor chip is attached and mounted on a printed circuit board, the electrical connection of the chip and the substrate is realized by a lead bonding method, and a resin, that is, an epoxy adhesive, is used for covering and wrapping to ensure reliability, in addition, the chip generates a large amount of heat in the process of operation, and the epoxy adhesive for covering and wrapping affects the heat dissipation efficiency, thereby causing the temperature of the chip to rise, and the chip runs in a high-temperature environment for a long time, which causes the aging speed to increase and the service life to decrease, and therefore a heat-conducting COB epoxy adhesive needs to be used.

[0003] A heat-conducting COB epoxy adhesive and a preparation method thereof are disclosed in Chinese patent CN102703012B, which is composed of the following raw materials in percentage of the total weight of the raw materials: 20-40% of epoxy resin, 2-10% of diluent, 25-73% of heat-conducting filler, 0-1% of coupling agent, 0-1% of dye, 0-1% of defoaming agent, 1-3% of thixotropic agent, 2-5% of curing agent and 1-3% of curing accelerator. The main technical point is to protect the functions of the chip in application, improve the operation speed, prolong the service life of the chip and make the operation of the chip more stable.

[0004] In summary, the preparation method of the existing heat-conducting COB epoxy adhesive is to add all the materials into a stirring machine at one time for stirring, without step-by-step stirring and stirring parameter setting in different stages, so that the agglomeration phenomenon and a large number of bubbles are easily generated due to the one-time addition of too much filler, the heat-conducting filler cannot be uniformly dispersed in the epoxy resin system, the formation of the heat-conducting network is affected, that is, the heat-conducting efficiency is affected, and the existence of a large number of bubbles reduces the compactness of the adhesive and affects the heat-conducting performance and mechanical properties. SUMMARY

[0005] In order to make up for the deficiencies of the prior art and solve at least one technical problem proposed in the background art.

[0006] The technical scheme adopted by the application to solve the technical problem is that the heat-conducting COB epoxy adhesive comprises the following components in parts by weight: 30-40 parts of bisphenol F862 epoxy resin, 2-5 parts of ethylene glycol diglycidyl ether, 40-60 parts of aluminum nitride, 1-5 parts of antimony oxide, 0.5-2 parts of silicone defoaming agent, 0.01-0.1 parts of ultramarine blue dye, 2-5 parts of fumed silica, 5-10 parts of methyl nadic anhydride and 0.5-2 parts of benzyl dimethylamine.

[0007] The application discloses a preparation method of a heat-conducting COB epoxy adhesive, and applies the heat-conducting COB epoxy adhesive. S1, selecting each raw material according to a set standard; S2, adding bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether into a double-row planetary stirrer with matched spiral stirring paddles, and stirring at 500-800 r / min for 15-20 minutes; S3, drying and screening the aluminum nitride, adding 30-40% of the total amount of the screened aluminum nitride into the stirrer, and stirring at 1000-1200 r / min for 30-40 minutes, then adding the remaining 60-70% of the aluminum nitride, antimony oxide and fumed silicon dioxide into the stirrer, and continuing to stir at the same speed for 40-60 minutes; S4, adding a silicone defoaming agent, stirring at 800-1000 r / min for 15-20 minutes to eliminate bubbles, and then adding ultramarine blue dye, and continuing to stir at the same speed for 10-15 minutes; S5, transferring the mixed material into a vacuum device, starting a vacuum pump to extract vacuum to-0.08 to-0.05 MPa, and maintaining the vacuum for 25-30 minutes; S6, adding methyl nadic anhydride and benzyldimethylamine, and stirring at 300-500 r / min for 10-15 minutes; S7, detecting the appearance, viscosity, thermal conductivity, curing time and shear strength of the obtained product, and sealing and packaging the qualified product for storage.

[0008] Further, the liquid raw materials of the bisphenol F862 epoxy resin and the ethylene glycol diglycidyl ether selected in the S1 stage are stored in a special warehouse which is cool, dry and ventilated, and the raw materials are prevented from being directly irradiated by sunlight, the storage temperature is controlled to be 20-25 DEG C, the relative humidity is controlled to be 40-60%, and the aluminum nitride is stored in a sealed container.

[0009] Further, the bisphenol F862 epoxy resin is detected in terms of molecular weight and distribution by using a gel permeation chromatograph, and the viscosity is detected by using a rotary viscometer; the purity of the ethylene glycol diglycidyl ether, the aluminum nitride, the antimony oxide, the methyl nadic anhydride and the benzyldimethylamine is detected; the defoaming performance and stability of the silicone defoaming agent are detected; the chroma and tinting strength of the ultramarine blue dye are detected; and the specific surface area and pH value of the fumed silicon dioxide are detected.

[0010] Further, the adhesion materials on the stirring kettle wall and the stirring paddle are scraped off during the stirring in the S2 and S3 stages, and the length of the pause is determined according to actual cleaning requirements.

[0011] Further, the drying and screening process of the aluminum nitride is as follows: Drying in an oven at 110-120℃ for 2.5-3 hours to remove moisture, and then screening through a vibrating screen to remove oversized and undersized materials.

[0012] Further, the defoaming effect is detected by a combination of manual observation and a bubble counter, and the defoaming standard is that the number of bubbles detected by the bubble counter is reduced to a set value within a specified time, and no obvious bubbles are observed by the naked eye.

[0013] Further, the appearance of the S7 stage product is detected according to whether the adhesive is uniform, layered or precipitated; the viscosity is measured by a rotary viscometer; the thermal conductivity is measured by a laser thermal conductivity instrument; the curing time is tested according to the standard curing conditions; and the shear strength is tested by a universal material testing machine.

[0014] Further, the product container is sealed and detected by the bubble method in the S7 stage, and the detection method of the bubble method is that the packaged adhesive is immersed in water, a certain pressure is applied, and whether bubbles come out is observed.

[0015] Further, the storage temperature of the packaged adhesive is 20-25℃, the relative humidity is 40-60%, and the storage is light-proof.

[0016] The beneficial effects of the present application are as follows: 1. The step-by-step stirring method is adopted, the bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether are pre-mixed, the solid raw materials such as aluminum nitride are added in steps, and different stirring speeds and times are set, so that the raw materials are fully contacted and dispersed, and the uniformity of mixing is improved, thereby avoiding the material agglomeration phenomenon caused by adding too much filler at one time, and avoiding a large number of bubbles caused by adding too much material, and further ensuring the thermal conductivity of the adhesive; 2. The defoaming effect is detected by a combination of manual observation and a bubble counter, which can accurately determine whether the defoaming is up to standard, ensure that the bubbles in the adhesive are fully eliminated, and further improve the density of the adhesive, and through the detection of appearance, viscosity, thermal conductivity, curing time and shear strength, the quality of the adhesive can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be further described below with reference to the accompanying drawings.

[0018] Figure 1 A flow chart for preparing a thermal conductive COB epoxy adhesive. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0020] Please refer to Figure 1 , The present embodiment provides: A kind of heat-conducting COB epoxy adhesive, including the following components by weight: bisphenol F862 epoxy resin 30-40 parts, ethylene glycol diglycidyl ether 2-5 parts, aluminum nitride 40-60 parts, antimony oxide 1-5 parts, silicone defoaming agent 0.5-2 parts, ultramarine blue dye 0.01-0.1 parts, fumed silica 2-5 parts, methyl nadic anhydride 5-10 parts and benzyl dimethylamine 0.5-2 parts.

[0021] It needs to be specially pointed out that bisphenol F862 epoxy resin is the matrix resin of the adhesive, which has excellent bonding performance. It can form a firm chemical bond and physical adsorption with various materials in COB packaging (such as chips, substrates), provide reliable bonding strength, and ensure the stability and reliability of electronic components after packaging; ethylene glycol diglycidyl ether as a reactive diluent, not only can reduce the viscosity of the adhesive, improve the construction performance, but also can participate in the curing reaction, increase the crosslinking density, so as to improve the toughness and bonding performance of the adhesive to a certain extent, so that the adhesive can better adapt to the stress change in the packaging process; aluminum nitride has very high thermal conductivity, which is the main functional filler for heat conduction. It can form an effective heat conduction path inside the adhesive, so that heat can be quickly transferred to meet the heat dissipation needs of electronic components in COB packaging, prevent the performance degradation or damage of components due to overheating; methyl nadic anhydride as a curing agent, benzyl dimethylamine as an accelerator, both of which can be used together to accurately control the curing speed and curing degree of the adhesive, and at the same time can make the adhesive form a highly crosslinked three-dimensional network structure after curing, which has good chemical stability and thermal stability, so that it can maintain its performance unchanged during long-term use, ensuring the long-term reliability of COB packaging; silicone defoaming agent can effectively eliminate these bubbles to ensure that the adhesive forms a dense structure after curing, and at the same time, the dense structure not only helps to improve the thermal conductivity and mechanical properties of the adhesive, but also improves the appearance of the adhesive, making its surface more uniform and smooth; ultramarine blue dye can give the adhesive a specific color, which is convenient for appearance identification and quality control during production; the role of fumed silica: fumed silica can quickly increase the viscosity of the adhesive, prevent the adhesive from flowing and shifting, and at the same time, this thixotropy ensures the accuracy of the adhesive in the packaging position, improves the packaging precision, and ensures the tight and reliable connection between the electronic components and the substrate.

[0022] The application discloses a preparation method of a heat-conducting COB epoxy adhesive. S1, selecting each raw material according to a set standard; S2, adding bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether into a double-planetary mixer with a spiral paddle, and stirring at 500-800 r / min for 15-20 minutes; S3, drying and screening the aluminum nitride, adding 30-40% of the total amount of the aluminum nitride after screening into the mixer, and stirring at 1000-1200 r / min for 30-40 minutes, then adding the remaining 60-70% of the aluminum nitride, antimony oxide and fumed silicon dioxide into the mixer, and continuing to stir at the same speed for 40-60 minutes; S4, adding a silicone defoaming agent, and stirring at 800-1000 r / min for 15-20 minutes to eliminate bubbles, then adding ultramarine blue dye, and continuing to stir at the same speed for 10-15 minutes; S5, transferring the mixed material into a vacuum device, starting a vacuum pump to extract vacuum to-0.08 to-0.05 MPa, and maintaining the vacuum for 25-30 minutes; S6, adding methyl nadic anhydride and benzyldimethylamine, and stirring at 300-500 r / min for 10-15 minutes; S7, detecting the appearance, viscosity, thermal conductivity, curing time and shear strength of the obtained product, and sealing and packaging the qualified product for storage.

[0023] The liquid raw materials of the bisphenol F862 epoxy resin and the ethylene glycol diglycidyl ether are stored in a special warehouse which is cool, dry and ventilated, and is avoided from being directly irradiated by sunlight, the storage temperature is controlled to be 20-25 DEG C, the relative humidity is controlled to be 40-60%, and the aluminum nitride is stored in a sealed container.

[0024] The bisphenol F862 epoxy resin is detected in terms of molecular weight and distribution by using a gel permeation chromatograph, and viscosity is measured by using a rotary viscometer; the purity of the ethylene glycol diglycidyl ether, the aluminum nitride, the antimony oxide, the methyl nadic anhydride and the benzyldimethylamine is detected, the defoaming performance and stability of the silicone defoaming agent are detected, the chroma and tinting strength of the ultramarine blue dye are detected, and the specific surface area and pH value of the fumed silicon dioxide are detected.

[0025] The adhesion materials on the stirring kettle wall and the stirring paddle are scraped off during the stirring in the stages S2 and S3, and the scraping-off time is determined according to actual cleaning requirements.

[0026] The drying and screening process of the aluminum nitride is as follows: Drying in an oven at 110-120℃ for 2.5-3 hours to remove moisture, and then screening through a vibrating screen to remove oversized and undersized materials.

[0027] The defoaming effect is detected by a combination of manual observation and bubble counting instrument, and the defoaming standard is that the number of bubbles detected by the bubble counting instrument is reduced to a set value within a specified time, and no obvious bubbles are observed by naked eye.

[0028] The appearance of the product in S7 stage is detected according to whether the adhesive is uniform, layered or precipitated; the viscosity is measured by a rotational viscometer; the thermal conductivity is measured by a laser thermal conductivity instrument; the curing time is tested according to the standard curing conditions; and the shear strength is tested by a universal material testing machine.

[0029] The product container is sealed and detected by the bubble method in S7 stage. The detection method of the bubble method is to immerse the packaged adhesive into water, apply a certain pressure, and observe whether bubbles come out.

[0030] The storage temperature of the packaged adhesive is 20-25℃, the relative humidity is 40-60%, and the storage is in the dark.

[0031] Example 1: A kind of heat-conducting COB epoxy adhesive, including the following components by weight: bisphenol F862 epoxy resin 30 parts, ethylene glycol diglycidyl ether 2 parts, aluminum nitride 40 parts, antimony oxide 1 part, silicone defoamer 0.5 parts, ultramarine blue dye 0.01 parts, fumed silica 2 parts, methyl nadic anhydride 5 parts and benzyl dimethylamine 0.5 parts.

[0032] A heat-conducting COB epoxy adhesive preparation method applied to a heat-conducting COB epoxy adhesive, including the following steps: S1, selecting each raw material according to the set standard; S2, adding bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether into a double-planetary mixer with a matching spiral paddle, and stirring at 500 rpm for 15 minutes; S3, drying and screening the aluminum nitride, and adding 30% of the total amount of aluminum nitride after screening into the mixer, and stirring at 1000-1200 rpm for 30 minutes, then adding the remaining 70% aluminum nitride, antimony oxide and fumed silica, and continuing to stir at the same speed for 60 minutes; S4, add silicone defoamer, stir at 800 rpm for 15 minutes to eliminate bubbles, and then add ultramarine blue dye, continue to stir at the same speed for 10 minutes; S5, transfer the mixed material to a vacuum device, start the vacuum pump to vacuum to-0.08 MPa, and the vacuum time is 25 minutes; S6, after adding methyl nadic anhydride and benzyl dimethylamine, stirring at 300 rpm for 10 minutes; S7, the obtained product was detected for appearance, viscosity, thermal conductivity, curing time and shear strength, and the qualified product was sealed and stored.

[0033] The liquid raw materials of bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether selected in S1 stage were stored in a special warehouse with shade, dryness and ventilation, avoiding direct sunlight, and the storage temperature was controlled at 20-25°C and the relative humidity was controlled at 40-60%. The aluminum nitride was stored in a sealed container.

[0034] For bisphenol F862 epoxy resin, the molecular weight and distribution were determined by gel permeation chromatography, and the viscosity was measured by rotary viscometer; the purity of ethylene glycol diglycidyl ether, aluminum nitride, antimony oxide, methyl nadic anhydride and benzyl dimethylamine was detected, and the defoaming performance and stability of silicone defoaming agent were detected; the color and coloring power of ultramarine blue dye were detected; the specific surface area and pH value of fumed silica were detected.

[0035] During stirring in S2 and S3 stages, the attached materials on the stirring kettle wall and stirring paddle were scraped off, and the length of the pause was determined according to the actual cleaning requirement.

[0036] The drying and screening process of aluminum nitride is as follows: Drying in an oven at 110°C for 2.5 hours to remove water, and then screening by a vibrating screen to remove oversized and undersized materials.

[0037] The defoaming effect was detected by artificial observation combined with bubble counting instrument, and the defoaming standard was that the number of bubbles detected by bubble counting instrument was reduced to below the set value within the specified time, and no obvious bubbles were observed by naked eye.

[0038] The detection of product appearance in S7 stage was based on whether the adhesive was uniform, layered or precipitated; the viscosity was measured by rotary viscometer; the thermal conductivity was measured by laser thermal conductivity instrument; the curing time was tested according to the standard curing condition; and the shear strength was tested by universal material testing machine.

[0039] In S7 stage, the product container was detected for sealing by bubble method, and the detection method of bubble method was that the packaged adhesive was immersed in water, a certain pressure was applied, and whether bubbles came out was observed.

[0040] The storage temperature of packaged adhesive was 20°C, the relative humidity was 40%, and the storage was in the dark.

[0041] Example 2: A thermally conductive COB epoxy adhesive comprises the following components, in parts by weight: 40 parts of bisphenol F862 epoxy resin, 5 parts of ethylene glycol diglycidyl ether, 60 parts of aluminum nitride, 5 parts of antimony oxide, 2 parts of silicone defoamer, 0.1 parts of ultramarine blue dye, 5 parts of fumed silica, 10 parts of methyl nadic anhydride, and 2 parts of benzyldimethylamine.

[0042] A method for preparing a thermally conductive COB epoxy adhesive, which is applied to a thermally conductive COB epoxy adhesive, comprises the following steps: S1. Select raw materials that meet the quality standards according to the set standards; S2. Add bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether into a double planetary mixer equipped with a twist paddle and stir at 800 rpm for 20 minutes; S3, drying and sieving the aluminum nitride, and adding 40% of the total amount of aluminum nitride after sieving to a blender, and stirring at a stirring speed of 1200 rpm for 40 minutes, and then adding the remaining 60% of the aluminum nitride, antimony oxide, and fumed silica, and continuing to stir at the same speed for 60 minutes; S4, adding silicone defoamer, stirring at 1000 rpm for 20 minutes to eliminate bubbles, adding ultramarine blue dye after sufficient defoaming, and continuing to stir at the same speed for 15 minutes; S5. Transfer the mixed materials to a vacuum device and start the vacuum pump to 0.05 MPa for 30 minutes. S6. After adding nadic methyl anhydride and benzyldimethylamine, stir at 500 rpm for 10-15 minutes; S7. The obtained product is tested for appearance, viscosity, thermal conductivity, curing time and shear strength, and qualified products are sealed and packaged for storage.

[0043] Bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether liquid raw materials are stored in a cool, dry, ventilated dedicated warehouse, avoiding direct sunlight. The storage temperature is controlled at 25°C and the relative humidity is controlled at 60%. Aluminum nitride is stored in a sealed container.

[0044] For bisphenol F862 epoxy resin, the molecular weight and distribution were determined by gel permeation chromatography, and the viscosity was measured using a rotational viscometer. The purity of ethylene glycol diglycidyl ether, aluminum nitride, antimony oxide, methyl nadic anhydride, and benzyldimethylamine was tested, and the defoaming performance and stability of the silicone defoamer were tested. The chroma and tinting strength of ultramarine blue dye were tested. The specific surface area and pH value of fumed silica were tested.

[0045] During the S2 and S3 stages, the device is paused during stirring to scrape off the attached materials on the wall of the stirring tank and the stirring paddle. The pause duration is determined according to the actual cleaning needs.

[0046] The dry screening process of aluminum nitride is as follows: Drying in an oven at 110-120℃ for 3 hours to remove moisture, and then screening by a vibrating screen to remove oversized and undersized materials.

[0047] The defoaming effect is detected by a combination of manual observation and bubble counting instrument, and the defoaming standard is that the number of bubbles detected by the bubble counting instrument is reduced to below the set value within the specified time, and no obvious bubbles are observed by naked eye.

[0048] The appearance of the product in S7 stage is detected according to whether the adhesive is uniform, layered or precipitated; the viscosity is measured by a rotational viscometer; the thermal conductivity is measured by a laser thermal conductivity instrument; the curing time is tested according to the standard curing conditions; and the shear strength is tested by a universal material testing machine.

[0049] The sealing of the product container in S7 stage is detected by the bubble method, and the detection method of the bubble method is to immerse the packaged adhesive into water and apply a certain pressure to observe whether bubbles come out.

[0050] The storage temperature of the packaged adhesive is 25℃, the relative humidity is 60%, and the storage is in the dark.

[0051] Example 3: A kind of heat-conducting COB epoxy adhesive, including the following components by weight: bisphenol F862 epoxy resin 35 parts, ethylene glycol diglycidyl ether 3 parts, aluminum nitride 50 parts, antimony oxide 3 parts, silicone defoamer 1 part, ultramarine blue dye 0.1 part, fumed silica 3 parts, methyl nadic anhydride 8 parts and benzyl dimethylamine 1 part.

[0052] A heat-conducting COB epoxy adhesive preparation method applied to a heat-conducting COB epoxy adhesive, including the following steps: S1, selecting each raw material with quality indicators meeting the set standards for standby; S2, adding bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether to a double-planetary mixer with matching spiral paddles, and stirring at 600 revolutions per minute for 17 minutes; S3, drying and screening aluminum nitride, and adding 35% of the total amount of aluminum nitride after screening to the mixer, and stirring at 1500 revolutions per minute for 35 minutes, then adding the remaining 65% of aluminum nitride, antimony oxide and fumed silica, and continuing to stir at the same speed for 50 minutes; S4, adding silicone defoamer, stirring at 900 revolutions per minute for 17 minutes to eliminate bubbles, and then adding ultramarine blue dye, and continuing to stir at the same speed for 12 minutes; S5, transfer the mixed material to the vacuum equipment, start the vacuum pump to vacuum to 0.06 MPa, the vacuum time is 27 minutes; S6, after adding methyl nadic anhydride and benzyl dimethylamine, stirring at 400 rpm for 12 minutes; S7, the appearance, viscosity, thermal conductivity, curing time and shear strength of the obtained product are detected, and the qualified product is sealed and packaged for storage.

[0053] The liquid raw materials of bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether are stored in a special warehouse with cool, dry and ventilated conditions, avoiding direct sunlight, and the storage temperature is controlled at 23°C and the relative humidity is controlled at 40-60%. Aluminum nitride is stored in a sealed container.

[0054] For bisphenol F862 epoxy resin, the molecular weight and distribution are determined by gel permeation chromatography, and the viscosity is measured by a rotary viscometer; the purity of ethylene glycol diglycidyl ether, aluminum nitride, antimony oxide, methyl nadic anhydride and benzyl dimethylamine is detected, and the defoaming performance and stability of the silicone defoaming agent are detected; the color and coloring power of the ultramarine blue dye are detected; the specific surface area and pH value of fumed silica are detected.

[0055] The S2 and S3 stages pause the device during stirring to remove the attached material on the stirring kettle wall and stirring paddle, and the pause time is determined according to the actual cleaning needs.

[0056] The drying and screening process of aluminum nitride is as follows: Dry in an oven at 115°C for 2.7 hours to remove moisture, then screen through a vibrating screen to remove oversized and undersized materials.

[0057] The defoaming effect is detected by a combination of manual observation and bubble counter, and the defoaming standard is that the number of bubbles detected by the bubble counter is reduced to below the set value within the specified time, and no obvious bubbles are observed by the naked eye.

[0058] The appearance of the product in S7 stage is detected according to whether the adhesive is uniform, layered or precipitated; the viscosity is measured by a rotary viscometer; the thermal conductivity is measured by a laser thermal conductivity instrument; the curing time is tested according to the standard curing conditions; and the shear strength is tested by a universal material testing machine.

[0059] The product container is sealed and detected by the bubble method in S7 stage, and the detection method of the bubble method is to immerse the packaged adhesive into water and apply a certain pressure to observe whether bubbles come out.

[0060] The storage temperature of the packaged adhesive is 23°C, the relative humidity is 50%, and the storage is in the dark.

[0061] Embodiment 4: A heat-conducting COB epoxy adhesive comprises the following components by weight: bisphenol F862 epoxy resin 37 parts, ethylene glycol diglycidyl ether 4 parts, aluminum nitride 52 parts, antimony oxide 4 parts, silicone defoaming agent 1.2 parts, ultramarine blue dye 0.01 parts, fumed silica 4 parts, methyl nadic anhydride 9 parts, and benzyldimethylamine 2 parts.

[0062] A heat-conducting COB epoxy adhesive preparation method applied to the heat-conducting COB epoxy adhesive, comprising the following steps: S1, selecting each raw material according to the set standard; S2, adding bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether to a double-planetary mixer with a mixing paddle, and stirring at 690 rpm for 18 minutes; S3, drying and sieving the aluminum nitride, and adding 39% of the total amount of aluminum nitride after sieving to the mixer and stirring at 1200 rpm for 39 minutes, then adding the remaining 69% of the aluminum nitride, antimony oxide and fumed silica, and continuing to stir at the same speed for 59 minutes; S4, adding silicone defoaming agent and stirring at 999 rpm for 17 minutes to eliminate bubbles, and then adding ultramarine blue dye and continuing to stir at the same speed for 12 minutes; S5, transferring the mixed material to a vacuum device, starting the vacuum pump to vacuum to 0.05 MPa, and the vacuum time is 26 minutes; S6, after adding methyl nadic anhydride and benzyldimethylamine, stirring at 480 rpm for 11 minutes; S7, the obtained product is detected for appearance, viscosity, thermal conductivity, curing time and shear strength, and the qualified products are sealed and packaged for storage.

[0063] The liquid raw materials of bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether are stored in a special warehouse that is cool, dry and ventilated, avoiding direct sunlight, and the storage temperature is controlled at 21℃ and the relative humidity is controlled at 40-60%, and the aluminum nitride is stored in a sealed container.

[0064] For bisphenol F862 epoxy resin, the molecular weight and distribution are determined by gel permeation chromatography, and the viscosity is measured by a rotary viscometer; the purity of ethylene glycol diglycidyl ether, aluminum nitride, antimony oxide, methyl nadic anhydride and benzyldimethylamine is detected, the defoaming performance and stability of silicone defoaming agent are detected, the color and coloring power of ultramarine blue dye are detected, and the specific surface area and pH value of fumed silica are detected.

[0065] S2 and S3 stages pause the device during stirring to scrape off the attached material on the stirring tank wall and stirring paddle, and the pause duration is determined according to the actual cleaning requirement.

[0066] The dry screening process of aluminum nitride is as follows: Drying in an oven at 110-120℃ for 2.9 hours to remove moisture, and then screening through a vibrating screen to remove oversized and undersized materials.

[0067] The defoaming effect is detected by a combination of manual observation and bubble counting instrument, and the defoaming standard is that the number of bubbles detected by the bubble counting instrument is reduced to below the set value within the specified time, and no obvious bubbles are observed by naked eye.

[0068] The appearance of the product in S7 stage is detected according to whether the adhesive is uniform, layered or precipitated; the viscosity is measured by a rotary viscometer; the thermal conductivity is measured by a laser thermal conductivity instrument; the curing time is tested according to the standard curing conditions; and the shear strength is tested by a universal material testing machine.

[0069] The product container is sealed and detected by the bubble method in S7 stage. The detection method of the bubble method is to immerse the packaged adhesive into water and apply a certain pressure to observe whether bubbles come out.

[0070] The packaged adhesive is stored at a temperature of 23℃ and a relative humidity of 52%, and is stored in the dark.

[0071] Table 1: From Table 1: The amount of bisphenol F862 epoxy resin is varied between 30-40 parts. Bisphenol F862 epoxy resin is the base resin of the adhesive. Increasing its amount appropriately can improve the bonding strength and mechanical properties of the adhesive, so that the adhesive forms a more firm bond with the materials in COB packaging, and improves the reliability of the packaging. The amount of ethylene glycol diglycidyl ether is varied between 2-5 parts. As an active diluent, increasing its amount appropriately can reduce the viscosity of the adhesive and improve the workability, and may also improve the toughness of the adhesive. The amount of aluminum nitride is varied between 40-60 parts. As the main functional filler for heat conduction, increasing its amount appropriately can significantly improve the thermal conductivity of the adhesive, and better meet the heat dissipation requirements of electronic components in COB packaging. The amount of antimony oxide is varied between 1-5 parts. Increasing its amount appropriately may help to improve the thermal conductivity and flame retardant properties of the adhesive. The amount of silicone defoaming agent is varied between 1-5 parts. Increasing its amount appropriately can more effectively eliminate bubbles in the adhesive, and improve the compactness and appearance quality of the adhesive. The amount of ultramarine blue dye varies between 0.01 and 0.1 parts. The ultramarine blue dye is mainly used to impart a specific color to the adhesive, facilitating appearance recognition and quality control during the production process. Increasing the amount of ultramarine blue dye appropriately can make the color more vibrant and uniform. The amount of fumed silica varies between 0.5 and 2 parts. Fumed silica is used to impart good thixotropic properties to the adhesive. Increasing the amount of fumed silica appropriately can improve the resistance to flow and displacement of the adhesive, ensuring the accuracy of the adhesive in the packaging position. The amount of methyl nadic anhydride varies between 5 and 10 parts. Methyl nadic anhydride is used as a curing agent. The amount of methyl nadic anhydride varies between 0.5 and 2 parts, and benzyl dimethylamine is used as an accelerator. The combination of the two controls the curing speed and degree of the adhesive. Increasing their amounts appropriately can accelerate the curing speed, improve the curing degree, make the adhesive form a more stable cross-linked structure, and thus improve the chemical stability and thermal stability of the adhesive.

[0072] The stirring time of the first step of the step-by-step stirring varies between 30 and 40 minutes, and the total amount varies between 30 and 40%. The stirring time of the second step varies between 40 and 60 minutes, and the total amount varies between 30 and 40%. Increasing the stirring time appropriately can improve the uniformity of mixing, and increasing the amount of material appropriately can improve the efficiency of mixing. The vacuum regulation air pressure varies between -0.08 and 0.05 MPa, and the time varies between 25 and 30 minutes. Increasing the time and regulation air pressure appropriately can facilitate the elimination of small bubbles and improve the density of the adhesive.

[0073] Comparative Example 1: Compared with Example 1, the amount of bisphenol F862 epoxy resin was increased to 50 parts, and the proportions of other raw materials were similar to those of Example 1. The preparation process was the same as that of Example 1.

[0074] Comparative Example 2: Compared with Example 2, the amount of aluminum nitride was reduced to 30 parts, and the proportions of other raw materials were similar to those of Example 2. The preparation process was the same as that of Example 2.

[0075] Comparative Example 3: Using the raw material ratio of Example 3, the step-by-step stirring and feeding operation was replaced by a one-time feeding and stirring operation, and the other preparation processes were the same as those of Example 3.

[0076] Comparative Example 4: Using the raw material ratio of Example 4, the drying and screening operations of aluminum nitride were cancelled, and the other preparation processes were the same as those of Example 4.

[0077] Table 2: From Table 2, it can be seen that: The raw material ratio exceeds the critical value (Comparative Example 1) Bisphenol F 862 epoxy resin is the matrix that bears the bonding strength in the adhesive, and its content increases from 30-40 parts to 50 parts, which leads to too large viscosity, which is not conducive to construction.

[0078] The raw material ratio is lower than the critical value (Comparative Example 2) Aluminum nitride is the key filler in the adhesive that bears the heat conduction function, and its content decreases from 40-60 parts to 30 parts, which makes the originally formed heat conduction network of aluminum nitride particles become sparse, and the heat transfer efficiency in the adhesive is greatly reduced. In the COB packaging, the heat generated by the electronic components cannot be dissipated in time, which will cause the temperature of the components to rise, thereby affecting their performance and service life, and at the same time, problems such as slow running speed of the components, signal distortion, and even damage may occur; The necessity of step-by-step stirring and feeding (Comparative Example 3) Replace the step-by-step stirring and feeding operation with a one-time feeding operation, i.e., add all the raw materials to the stirrer at the same time. Due to the large difference in physical properties (such as density, particle size, viscosity, etc.) of the raw materials, uniform mixing cannot be achieved in a short time. For example, solid fillers such as aluminum nitride may agglomerate during stirring, resulting in local concentration that is too high or too low, affecting the overall performance of the adhesive. Secondly, uneven mixing will lead to uneven distribution of heat-conducting fillers such as aluminum nitride in the adhesive, and the formation of an effective heat-conducting path, i.e., some areas may have too much heat-conducting filler, while some areas have too little, which hinders the heat transfer in the adhesive and reduces the heat-conducting performance of the adhesive. At the same time, uneven mixing may also cause stress concentration points in the adhesive, affecting its mechanical properties and stability. Moreover, one-time feeding operation may generate more air bubbles during stirring; The necessity of drying and screening operations on aluminum nitride (Comparative Example 4) If the drying and screening operations are not performed on the aluminum nitride, moisture will remain on the surface or inside the aluminum nitride particles, and the moisture will generate pores during the curing process of the adhesive, which will destroy the continuity of the heat conduction path and reduce the heat conduction performance of the adhesive. In addition, the moisture will react with other components in the adhesive, affecting the chemical stability and heat conduction performance of the adhesive. In addition, the aluminum nitride that has not been screened may contain particles that are too large or too small. The particles that are too large are difficult to disperse uniformly in the adhesive and are prone to form agglomerates, affecting the flowability and construction performance of the adhesive and hindering the heat transfer. The particles that are too small may increase the viscosity of the adhesive, which is not conducive to stirring and construction. In addition, the particles that are too small are more likely to be oxidized, affecting the heat conduction performance. In addition, the presence of moisture and agglomerates will also affect the curing process and performance of the adhesive after curing. That is, the moisture may cause incomplete curing reaction, resulting in unreacted components, reducing the mechanical properties and chemical stability of the adhesive. The agglomerates may form stress concentration points in the adhesive, making the adhesive prone to cracking or damage when subjected to external force, affecting the reliability of the COB packaging.

[0079] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0080] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A thermally conductive COB epoxy adhesive, characterized in that: The invention comprises the following components in parts by weight: 30-40 parts of bisphenol F862 epoxy resin, 2-5 parts of ethylene glycol diglycidyl ether, 40-60 parts of aluminum nitride, 1-5 parts of antimony oxide, 0.5-2 parts of organosilicon defoaming agent, 0.01-0.1 parts of ultramarine blue dye, 2-5 parts of fumed silica, 5-10 parts of methyl nadic anhydride and 0.5-2 parts of benzyldimethylamine.

2. A method for preparing a thermally conductive COB epoxy adhesive, applied to the thermally conductive COB epoxy adhesive according to claim 1, characterized in that: The following steps are involved: S1. Select raw materials that meet the quality standards according to the set standards; S2. Add bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether into a double planetary mixer equipped with a twist paddle and stir at 500-800 rpm for 15-20 minutes; S3, drying and screening the aluminum nitride, adding 30-40% of the total amount of aluminum nitride after screening into a blender, and stirring at a stirring speed of 1000-1200 rpm for 30-40 minutes, and then adding the remaining 60-70% of the aluminum nitride, antimony oxide, and fumed silica, and continuing to stir at the same speed for 40-60 minutes; S4. Add silicone defoamer and stir at 800-1000 rpm for 15-20 minutes to eliminate bubbles. After sufficient defoaming, add ultramarine blue dye and continue stirring at the same speed for 10-15 minutes. S5. Transfer the mixed materials to a vacuum device and start the vacuum pump to evacuate to -0.08-0.05 MPa for 25-30 minutes. S6. After adding nadic methyl anhydride and benzyldimethylamine, stirring at a speed of 300-500 rpm for 10-15 minutes; S7. The obtained product is tested for appearance, viscosity, thermal conductivity, curing time and shear strength, and qualified products are sealed and packaged for storage.

3. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The bisphenol F862 epoxy resin and ethylene glycol diglycidyl ether liquid raw materials selected in the S1 stage are stored in a cool, dry, ventilated dedicated warehouse, avoiding direct sunlight. The storage temperature is controlled at 20-25° C. and the relative humidity is controlled at 40-60%. The aluminum nitride is stored in a sealed container.

4. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: For bisphenol F862 epoxy resin, the molecular weight and distribution were determined by gel permeation chromatography, and the viscosity was measured using a rotational viscometer. The purity of ethylene glycol diglycidyl ether, aluminum nitride, antimony oxide, methyl nadic anhydride, and benzyldimethylamine was tested, and the defoaming performance and stability of the silicone defoamer were tested. The chroma and tinting strength of ultramarine blue dye were tested; the specific surface area and pH value of fumed silica were tested.

5. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: In the S2 and S3 stages, the device is paused during stirring to scrape off the attached materials on the wall of the stirring tank and the stirring paddle. The pause duration is determined according to actual cleaning needs.

6. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The drying and screening process of aluminum nitride is as follows: Dry in an oven at 110-120°C for 2.5-3 hours to remove moisture, then screen through a vibrating screen to remove oversized and undersized materials.

7. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The defoaming effect is detected by combining manual observation with a bubble counter. The defoaming standard is that the number of bubbles detected by the bubble counter is reduced to below the set value within the specified time, and there are no obvious bubbles when observed with the naked eye.

8. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The appearance of the product in the S7 stage is tested by observing whether the adhesive is uniform, stratified, or precipitated; the viscosity is measured using a rotational viscometer; Thermal conductivity is measured using a laser thermal conductivity meter; curing time is tested according to standard curing conditions; The shear strength was tested using a universal material testing machine.

9. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The S7 stage uses the bubble method to test the sealing of the product container. The bubble method is to immerse the packaged adhesive in water, apply a certain pressure, and observe whether bubbles emerge.

10. The method for preparing a thermally conductive COB epoxy adhesive according to claim 2, wherein: The packaged adhesive is stored at a temperature of 20-25° C. and a relative humidity of 40-60%, and is stored away from light.

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