High-performance electronic packaging adhesive based on graphene composite diamond micro-powder and preparation method of high-performance electronic packaging adhesive

Abstract

The invention relates to a high-performance electronic packaging adhesive based on graphene composite diamond micro-powder and a preparation method of the high-performance electronic packaging adhesive. By adding surface-modified graphene composite diamond micro-powder and a fumed silica dispersing agent into an epoxy resin system, an efficient heat-conducting grid is formed in a resin matrix, so that the heat-conducting effect is remarkably improved, the interface interaction between a heat-conducting filler and the resin matrix is synergistically and efficiently enhanced, and the compatibility is improved; the influence on the processability and the mechanical property of the resin matrix when a large amount of heat-conducting filler is conventionally added is avoided. In addition, a self-developed liquid nitrogen-phosphorus flame retardant and a toughening agent are added, so that the packaging adhesive has good flame retardance and toughness while high heat conductivity is ensured. The proportion range of the modified graphene composite diamond micropowder and fumed silica is determined by optimizing the formula, the addition amount of the heat-conducting filler in the packaging adhesive is reduced to the maximum extent, the reaction cost is effectively reduced, and meanwhile, the advantages of high heat conductivity, high flame retardance and good toughness of the packaging adhesive are synergistically realized. The packaging adhesive is suitable for the field of wider electronic packaging materials.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging adhesives, and particularly relates to a high-performance electronic packaging adhesive based on graphene composite diamond micropowder and a preparation method thereof. Background Art

[0002] The rapid development of the electronic information industry has promoted the trend of miniaturization and integration of electronic components, resulting in a sharp increase in the internal heat of devices. The service life and safety of chips are severely tested, and there is also a potential fire hazard. Therefore, the development of packaging adhesive materials with fast and efficient heat dissipation and good flame retardancy plays a key role in improving the working stability and service life of electronic products. Among them, epoxy resin packaging adhesives are considered to be one of the matrices of thermosetting packaging materials with the widest application prospects because of their strong bonding force, low curing shrinkage rate, simple preparation process, and excellent high-temperature resistance and electrical insulation properties.

[0003] At present, the application of epoxy resin packaging adhesives in the field of electronic devices has the following problems: 1. Their own thermal conductivity is low and they are extremely flammable, laying a safety hazard for "thermal runaway"; 2. When a large amount of heat-conducting powder materials and solid flame retardants are commonly added to improve the performance of the packaging adhesive, problems such as poor compatibility with the epoxy resin matrix and easy agglomeration and precipitation are likely to occur, resulting in an increase in viscosity and a deterioration in the construction fluidity. 3. During curing, epoxy resin is also prone to stress concentration due to the highly concentrated crosslinking density, leading to problems such as excessive hardness and cracking, which limits its application scope in the field of electronic components.

[0004] The thermal conductivity of diamond is as high as 2000 W / m·K, far higher than that of conventional heat-conducting materials such as gold, silver, copper, aluminum nitride, etc. It is an excellent heat-conducting filler. Diamond micropowder is usually a by-product in the production of diamond, with sufficient raw materials and low prices. However, the particle size of such materials is small, and a good filling structure cannot be formed with the organic epoxy resin colloid, thus affecting the construction of the heat-conducting grid and failing to achieve good thermal conductivity.

[0005] Therefore, it is urgent to modify diamond micropowder and explore the design of a new liquid flame retardant system to develop an epoxy resin packaging material with both high thermal conductivity and high flame retardancy and good toughness, and to achieve a balanced improvement of multiple properties, which has important practical significance for the upgrading and development of the electronic industry. Summary of the Invention

[0006] In order to solve the problem of poor thermal conductivity caused by interface effects and uneven dispersion when diamond micropowder is directly used in electronic packaging adhesives, and to synergistically improve the flame retardancy and toughness of the packaging adhesive, the purpose of the present invention is to provide a high-performance electronic packaging adhesive based on graphene composite diamond micropowder and its preparation method. By modifying graphene on the surface of diamond micropowder and using a surfactant for modification treatment, and adding fumed silica as a dispersant, the "interface interaction" between the thermal conductive filler and the resin matrix is synergistically enhanced, and the compatibility is improved, thereby solving the influence of excessive addition of fillers on the processing performance and mechanical properties of the resin matrix. At the same time, a self-developed liquid nitrogen-phosphorus flame retardant and different types of toughening agents are added to ensure that the epoxy resin packaging adhesive has good flame retardancy and toughness while having high thermal conductivity. In addition, through formula exploration, the present invention determines a specific proportion range of modified graphene composite diamond micropowder and fumed silica, which not only minimizes the addition amount of thermal conductive fillers in the packaging adhesive, but also synergistically realizes the advantages of high thermal conductivity, high flame retardancy and good toughness of the packaging adhesive.

[0007] To achieve the above object, the present invention provides a high-performance electronic packaging adhesive based on graphene composite diamond micropowder, and the raw material components and their weight fraction ratios are as follows:

[0008] 80-100 parts of epoxy resin matrix;

[0009] 1-3 parts of graphene composite diamond micropowder thermal conductive filler;

[0010] 30-55 parts of fumed silica dispersant;

[0011] 2-7 parts of nitrogen and phosphorus containing liquid flame retardant;

[0012] 3-8 parts of toughening agent;

[0013] 3-150 parts of curing agent;

[0014] The raw material ratio should meet the following conditions: control the fraction ratio of the thermal conductive filler to the fumed silica in the components to be in the range of 1:(30-45);

[0015] The molecular structure of the nitrogen and phosphorus containing liquid flame retardant is as follows:

[0016]

[0017] Furthermore, the particle diameter of the diamond micropowder is between 0.2-2 μm.

[0018] Further, the graphene composite diamond micropowder is synthesized through the following steps: (1) The diamond micropowder is pickled to remove the surface ash layer and form carboxyl or hydroxyl groups on the surface, where the pickling solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 2:1; (2) The diamond micropowder and the graphene mixed solution are freeze-dried to form an aerogel; the mass ratio of the diamond micropowder to the graphene ranges from 1:(0.2 - 0.5).

[0019] Further, the particle size of the fumed silica is between 7 - 50 nm.

[0020] Further, the encapsulation glue matrix is at least one of hydrogenated bisphenol A epoxy resin, hydrogenated bisphenol F epoxy resin, and phenolic epoxy resin.

[0021] Further, the toughening agent is at least one of carboxyl-terminated nitrile rubber, isoprene rubber, polybutadiene rubber, and epoxidized polybutadiene.

[0022] Further, the curing agent is at least one of boron trifluoride monoethylamine, boron trifluoride-piperidine, boron trifluoride-aniline, boron trifluoride-triethylenetetramine, and dicyandiamide / 2-methylimidazole.

[0023] Further, a preparation method of a high-performance electronic encapsulation glue based on graphene composite diamond micropowder comprises the following steps:

[0024] (1) According to certain weight fractions, an epoxy resin matrix, a nitrogen / phosphorus-containing liquid flame retardant, fumed silica, and a toughening agent are added to a high-speed shear disperser for strong stirring, and then a thermally conductive filler modified with a surface modifier is added, and stirring and mixing are continued to obtain Component A;

[0025] (2) A curing agent is added to Component A obtained in step (1), and mechanical stirring and mixing are carried out uniformly to obtain Component B;

[0026] (3) Component B obtained in step (2) is poured into a self-made mold and placed in a vacuum drying oven for heat preservation and exhaust treatment, and then heated and cured, and finally cooled to room temperature to obtain an epoxy resin encapsulation glue material.

[0027] This high-performance electronic encapsulation glue synergistically enhances the thermal conductivity, flame retardancy, and toughness of the epoxy resin-based electronic encapsulation glue material by the graphene composite diamond micropowder thermally conductive filler, the self-developed nitrogen / phosphorus-containing liquid flame retardant, and the toughening agent.

[0028] Furthermore, the preparation method of a high-performance electronic packaging adhesive based on graphene composite diamond micropowder is characterized in that the surface modifier for modifying the heat-conducting powder in step (1) is at least one of silane coupling agents such as γ-glycidoxypropyltrimethoxysilane (KH560), γ-methacryloxypropyltrimethoxysilane (KH570), and bis(γ-triethoxysilylpropyl)tetrasulfide (CG-Si69).

[0029] Furthermore, the preparation method of a high-performance electronic packaging adhesive based on graphene composite diamond micropowder is characterized in that the temperature of vacuum exhaust is 40-60°C, the exhaust time is 10-40 min, the curing temperature is 60-140°C, and the curing time is 2-10 h.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] The present invention uses surface-modified graphene composite diamond micropowder as a heat-conducting filler to cooperate with a fumed silica dispersant. By effectively improving the interfacial interaction between the heat-conducting filler and epoxy resin, it ensures that the packaging adhesive has good construction fluidity and effectively avoids the problem of poor compatibility with the organic matrix caused by adding a large amount of heat-conducting powder filler to increase the thermal conductivity. At the same time, the hydrophobic property of fumed silica assists the graphene composite diamond micropowder to form an efficient heat-conducting network in the epoxy resin matrix, enhancing the heat-conducting effect. The reduction in the usage amount of the heat-conducting filler can effectively reduce the production cost and is beneficial to improving the thermal conductivity and application range of the epoxy resin packaging adhesive. Secondly, silica can also play a synergistic flame-retardant role with a nitrogen / phosphorus-containing liquid flame retardant to jointly promote the formation of a high-strength and high-thermal-stability carbon protection layer, significantly improving the flame retardancy of the composite material; adding a green toughening modifier can effectively enhance the impact resistance of the epoxy resin packaging adhesive and avoid the cracking problem caused by the high hardness of the colloid due to a large crosslinking density.

[0032] (1) The production process of the present invention is simple and the production cost is low. The prepared epoxy resin packaging material has excellent thermal conductivity, flame retardancy, and good toughness. The thermal conductivity reaches 8.6 W / mK, and the flame retardancy meets the V-0 level flame retardant standard.

[0033] (2) The epoxy resin packaging material in the present invention has excellent uniformity and impact resistance. Detailed implementation manners

[0034] To make the present invention clearer and more definite, the following embodiments further illustrate the present invention in detail. It should be understood that the specific embodiments described herein are only used to explain the present invention and should not be construed as limiting the scope of the present invention. It should be noted that all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0035] In the following examples and comparative examples, diamond micropowder was purchased from Zhengzhou Huajing Diamond Co., Ltd., epoxy resin matrix material was purchased from Anhui Xinyuan Technology Co., Ltd., fumed silica, graphene, and curing agent were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the toughening agent was purchased from Shenzhen Masni Elastomer Co., Ltd. Reagents or instruments without indicating the manufacturer can be obtained as conventional products through commercial purchase.

[0036] Example 1

[0037] A preparation method of a high-performance electronic packaging adhesive based on graphene composite diamond micropowder is as follows:

[0038] (1) Modify the diamond micropowder

[0039] (a) First, add 100 parts of diamond micropowder with a particle size of 1 μm to 50 mL of a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 2:1, perform hydrothermal treatment at 100 °C for 2 h, cool to room temperature, wash with ultrapure water until the filtrate is neutral, and dry at 80 °C for 6 h to obtain pretreated diamond micropowder; then add 50 parts of diamond micropowder to an aqueous solution containing 15 parts of graphene, perform ultrasonic treatment for 10 min to make it evenly mixed, and treat in a freeze dryer for 12 - 24 h to obtain an aerogel.

[0040] (b) Pour 100 parts of the graphene composite diamond micropowder aerogel obtained in step (a) into a high-speed mixer, add 8 parts of the surface modifier sample in the form of a spray to the mixer under stirring, then raise the temperature to a fixed 80 °C and continue stirring for 1 h, and finally seal and store after baking at 120 °C for 2 h.

[0041] (2) Preparation of epoxy resin packaging adhesive

[0042] (a) Add 100 parts of hydrogenated bisphenol A epoxy resin, 6 parts of nitrogen / phosphorus-containing liquid flame retardant, 40 parts of nano-fumed silica, and 5 parts of polybutadiene rubber to a high-speed shear disperser for strong stirring, then add 2 parts of graphene composite diamond micropowder thermal conductive filler modified by KH570, and continue stirring and mixing to obtain component A;

[0043] (b) Add 10 parts of boron trifluoride - piperidine curing agent to component A obtained in step (1), stir and mix evenly to obtain component B;

[0044] (c) Pour Component B into a self-made mold and then place it in a vacuum drying oven for heat preservation and exhaust treatment at 50 °C for 30 min, then raise the temperature to 90 °C for curing treatment for 4 h, and finally cool it to room temperature to obtain the epoxy resin encapsulation adhesive material.

[0045] Example 2

[0046] The difference from Example 1 is that the addition amount of graphene when preparing the graphene composite diamond micropowder in step (1) is changed to 20 parts, and the others are the same as in Example 1.

[0047] Example 3

[0048] The difference from Example 1 is that the addition amount of the graphene composite diamond micropowder surface-modified by KH570 in step (2) is changed to 3 parts, and the others are the same as in Example 1.

[0049] Example 4

[0050] The difference from Example 1 is that the graphene composite diamond micropowder surface-modified by KH570 in step (2) is changed to diamond micropowder, and the others are the same as in Example 1.

[0051] Example 5

[0052] The difference from Example 1 is that the addition amount of fumed silica in step (2) is changed to 50 parts, and the addition amount of the graphene composite diamond micropowder surface-modified by KH570 is changed to 2.5 parts, and the others are the same as in Example 1.

[0053] Example 6

[0054] The difference from Example 1 is that the addition amount of the graphene composite diamond micropowder surface-modified by KH570 in step (2) is changed to 1 part, the addition amount of the nitrogen / phosphorus liquid flame retardant is changed to 5 parts, and the addition amount of polybutadiene rubber is changed to 8 parts, and the others are the same as in Example 1.

[0055] Example 7

[0056] The difference from Example 1 is that the addition amount of the nitrogen / phosphorus-containing liquid flame retardant in step (2) is changed to 7 parts, and the others are the same as in Example 1.

[0057] Example 8

[0058] The difference from Example 1 is that the addition amount of fumed silica in step (2) is changed to 55 parts, and the others are the same as in Example 1.

[0059] Control Example 1

[0060] The difference from Example 1 is that in step (2), no flame retardant is added, and the others are the same as in Example 1.

[0061] Comparative Example 2

[0062] The difference from Example 1 is that in step (2), no heat-conducting filler is added, and the others are the same as in Example 1.

[0063] Comparative Example 3

[0064] The difference from Example 1 is that in step (2), no toughening agent is added, and the others are the same as in Example 1.

[0065] Comparative Example 4

[0066] The difference from Example 1 is that in step (2), no fumed silica is added, and the others are the same as in Example 1.

[0067] Thermal conductivity test: The thermal conductivity of the encapsulant is tested according to ASTM D5470 standard;

[0068] Flame retardancy test: The vertical burning test meets the test requirements of V-0 level according to UL-94 standard on a CZF-2 type vertical burning tester. The limiting oxygen index is tested using an HC-2 type oxygen index meter according to GB / T 2406-2008.

[0069] Mechanical property test: The tensile strength and elongation at break are tested using a tensile testing machine according to the method of GB / T 528-2009, and the tensile rate is set at 200 mm / min.

[0070]

[0071] It can be seen from the above various examples, comparative examples and the corresponding performance test analysis tables that the epoxy resin encapsulant prepared by adding modified graphene composite diamond micropowder has a relatively high thermal conductivity, and the greater the addition amount of the modified graphene composite diamond micropowder, the better the thermal conductivity of the epoxy resin encapsulant, which is more conducive to rapid heat dissipation and expands the application range of electronic packaging materials. The addition of fumed silica dispersant can synergistically enhance the thermal conductivity of the modified graphene composite diamond micropowder and the flame retardancy of the encapsulant. When the epoxy resin encapsulant prepared by adding a self-developed nitrogen / phosphorus-containing liquid flame retardant can reach the flame retardant V-0 grade, and the increase in the addition amount of the flame retardant is beneficial to improving the combustion resistance of the encapsulant. The addition of epoxidized polybutadiene as a toughening agent significantly increases the tensile strength and elongation at break of the epoxy resin encapsulant, which is beneficial to improving the impact resistance and the cracking problem caused by excessive hardness.

[0072] In summary, the high-performance electronic packaging adhesive based on graphene composite diamond micropowder provided by the present invention effectively solves the problem of poor compatibility between the resin matrix and the thermal conductive filler in the existing method of improving the thermal conductivity of the epoxy resin matrix by adding a large amount of thermal conductive fillers. It synergistically uses fumed silica dispersant to further improve the thermal conductivity of the graphene composite diamond micropowder and assist the liquid flame retardant to enhance the flame retardant performance of the packaging adhesive, making the packaging adhesive applicable to a wider field of electronic packaging materials.

Claims

1. A high-performance electronic packaging adhesive based on graphene composite diamond micropowder, characterized in that, The raw material components and their weight fraction ratios are as follows: 80 - 100 parts of epoxy resin matrix; 1 - 3 parts of graphene composite diamond micropowder thermal conductive filler; 30 - 55 parts of fumed silica dispersant; 2 - 7 parts of nitrogen and phosphorus containing liquid flame retardant; 3 - 8 parts of toughening agent; 3 - 15 parts of curing agent; The raw material ratio should meet the following conditions: control the ratio range of the thermal conductive filler to fumed silica in the components to be 1:(30 - 45); The molecular structure of the nitrogen and phosphorus containing liquid flame retardant is as follows:

2. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, wherein Among them, the particle diameter of the diamond micropowder is between 0.2 - 2 μm.

3. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, wherein, Among them, the graphene composite diamond micropowder is synthesized through the following steps: (1) Pickle the diamond micropowder to remove the surface ash layer and form carboxyl or hydroxyl groups on the surface. Among them, the pickling solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 2:1; (2) Freeze-dry the mixed solution of diamond micropowder and graphene to form an aerogel; the mass ratio range of diamond micropowder to graphene is 1:(0.2 - 0.5).

4. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, wherein, Among them, the particle size of the fumed silica is between 7 - 50 nm.

5. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, wherein, Among them, the encapsulant matrix is at least one of hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, and phenolic epoxy resin.

6. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, characterized in that, Among them, the toughening agent is at least one of carboxyl-terminated nitrile rubber, isoprene rubber, polybutadiene rubber, and epoxidized polybutadiene.

7. The high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 1, wherein Among them, the curing agent is at least one of boron trifluoride monoethylamine, boron trifluoride-piperidine, boron trifluoride-aniline, boron trifluoride-triethylenetetramine, and dicyandiamide / 2-methylimidazole.

8. The preparation method of the high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to any one of claims 1 to 7, characterized in that, It includes the following steps: (1) Add the epoxy resin matrix, nitrogen / phosphorus containing liquid flame retardant, fumed silica, and toughening agent according to certain weight fractions into a high-speed shear disperser for strong stirring, and then add the surface-modified thermal conductive filler, and continue to stir and mix to obtain Component A; (2) Add the curing agent to the Component A obtained in step (1), and mechanically stir and mix evenly to obtain Component B; (3) Pour the Component B obtained in step (2) into a self-made mold, place it in a vacuum drying oven for heat preservation and exhaust treatment, then heat up for curing, and finally cool to room temperature to obtain the epoxy resin encapsulant material.

9. The preparation method of a high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 8, wherein, The surface modifier for modifying the thermal conductive powder in step (1) is at least one of silane coupling agents such as γ-glycidoxypropyltrimethoxysilane (KH560), γ-methacryloxypropyltrimethoxysilane (KH570), and bis(γ-triethoxysilylpropyl)tetrasulfide (CG-Si69).

10. The preparation method of a high-performance electronic packaging adhesive based on graphene composite diamond micropowder according to claim 8, characterized in that, The temperature for vacuum exhaust is 40 - 60 °C, the exhaust time is 10 - 40 min, the curing temperature is 60 - 140 °C, and the curing time is 2 - 10 h.

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