A high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging, its preparation method and application

Abstract

This invention discloses a high thermal conductivity and microwave-absorbing carbon fiber composite material for semiconductor packaging, its preparation method, and its application, belonging to the field of semiconductor technology. The method includes the following steps: activating millimeter-long carbon fibers with concentrated nitric acid; modifying the activated carbon fibers with polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate to obtain modified carbon fibers; coating the surface of carbonyl iron with silica to obtain coated carbonyl iron; refluxing and modifying the coated carbonyl iron with 3-aminopropyltriethoxysilane to obtain modified carbonyl iron; and capping the hydroxyl groups. Polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane are mixed to form an organosilicon resin. The organosilicon resin, modified carbon fiber, and modified carbonyl iron are mixed and stirred to obtain an organosilicon resin mixture. The organosilicon resin mixture is extruded, with the extrusion head of the extruder having a circular orifice, to obtain organosilicon resin rods. The organosilicon resin rods are arranged neatly and extruded to obtain a blocky high thermal conductivity microwave-absorbing carbon fiber composite material. This preparation method improves the insulation, thermal conductivity, and microwave absorption properties of the material, meeting the performance requirements of high thermal conductivity microwave-absorbing materials for semiconductor packaging.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a high thermal conductivity microwave absorbing carbon fiber composite material for semiconductor packaging, its preparation method, and its application. Background Technology

[0002] Semiconductors are key components in industries such as microelectronics, power transmission, and information communication, and are widely used in new energy vehicles, smart grids, 5G communications, and big data centers, serving as a guarantee and support for China's modernization. Semiconductor chips require packaging and testing before they can be applied to various systems. Device performance is directly affected by chip packaging, making microwave absorbing materials with high thermal conductivity and high microwave absorption properties crucial for improving the overall performance of semiconductors. High thermal conductivity microwave absorbing carbon fiber composites possess excellent electrical properties and aging resistance, and also aid in packaging stress release, thus finding wide application in power module packaging. They effectively enhance packaging insulation performance, isolate moisture and dust, and ensure reliable and long-life operation of power chips and interconnect circuits. After packaging with high thermal conductivity microwave absorbing carbon fiber composites, the heat generated by the semiconductor chip during operation can be effectively released, while also providing good protection for the semiconductor chip. Currently, the market for high thermal conductivity microwave absorbing carbon fiber composites is mainly monopolized by large foreign companies, which are both core suppliers of raw materials and deep participants in downstream products. With the advancement of power semiconductor chips towards higher power and the development of SiC modules, higher demands are being placed on high thermal conductivity absorbing carbon fiber composite materials, primarily towards higher temperature and pressure resistance and greater reliability. However, currently used high thermal conductivity absorbing carbon fiber composite materials for encapsulating high-power semiconductor devices still face numerous technical bottlenecks in terms of high temperature resistance and pressure resistance. For example, regarding high temperature resistance, when devices are exposed to temperatures above 150°C for extended periods, high thermal conductivity absorbing carbon fiber composite materials are prone to yellowing, increased hardness, and even cracking, resulting in a complete loss of their protective function for the device. Therefore, improving the high-temperature resistance to yellowing and thermal stability of high thermal conductivity absorbing carbon fiber composite materials is crucial for optimizing semiconductor device performance.

[0003] Shenzhen Hongfucheng Shielding Materials Co., Ltd. published a patent application with application number 202010997295.X in 2020. This invention uses a wire-winding process, in which carbon fibers are first wound in a specific direction onto a frame, and then cured and shaped. While this process solves the technical problem of carbon fiber orientation to some extent, it has drawbacks such as complex process and stringent requirements for carbon fibers—it requires the use of long, uncut carbon fibers, resulting in high costs. Therefore, it is not suitable for the more economical scenario of preparing short carbon fibers.

[0004] The Zhuhai Modern Industry Innovation Research Institute of South China University of Technology published a patent application (application number 201910575761.2) in 2019. The process of this invention involves removing a composite membrane from a filter membrane, placing it in a mold under pressure, then placing it in a tube furnace, introducing a protective gas, heating it to 1000-1500℃ and holding it at that temperature, ultimately obtaining a magnetic carbon fiber graphene composite membrane. In this invention, the magnetic carbon fibers are parallelly distributed within the graphene sheets under the action of an external magnetic field, achieving a parallelism rate of 85%-95%. Although this method can achieve a high carbon fiber parallelism rate, the parallel processing requires high-temperature treatment under a protective atmosphere, which is not only complex but also energy-intensive.

[0005] In 2020, Shaanxi University of Science and Technology published a patent application with application number 202011492137.5. This patent designs uniformly distributed directional holes between the right end of the nozzle outlet and the nozzle itself to ensure highly oriented short-cut carbon fibers in the slurry flowing out of the directional holes. While this method can solve the problem of fiber inorientation during the molding process of traditional short-fiber reinforced ceramic matrix composites to some extent, ceramic materials have high viscosity, making it difficult for the oriented carbon fibers to distribute randomly after orientation; and for materials with lower viscosity, the orientation effect is difficult to guarantee. Furthermore, this patent does not provide orientation indicators, making it impossible to determine the orientation level of the carbon fibers.

[0006] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high thermal conductivity absorbing carbon fiber composite material for semiconductor packaging, its preparation method and application, aiming to solve the problems of low dielectric properties, poor yellowing resistance and thermal stability of existing high thermal conductivity absorbing carbon fiber composite materials for semiconductor packaging.

[0008] The technical solution of the present invention is as follows: A first aspect of the present invention provides a method for preparing a high thermal conductivity, microwave-absorbing carbon fiber composite material for semiconductor packaging, comprising the following steps: A. Provide carbon fibers in millimeter lengths and activate the carbon fibers using concentrated nitric acid; B. The activated carbon fibers were modified by using polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate to obtain modified carbon fibers. C. Provide carbonyl iron, and coat the surface of the carbonyl iron with silicon dioxide to obtain coated carbonyl iron; D. The coated carbonyl iron was modified by reflux using 3-aminopropyltriethoxysilane to obtain modified carbonyl iron; E. Mix hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated dimethylsiloxane and side-chain vinyl polydimethylsiloxane to form an organosilicon resin. F. Mix the organosilicon resin, the modified carbon fiber, and the modified carbonyl iron, and stir to obtain an organosilicon resin mixture; G. The silicone resin mixture is extruded through an extruder, wherein the extrusion head of the extruder is a round hole, to obtain silicone resin round rods; H. The silicone resin rods are arranged neatly and extruded to obtain a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

[0009] Optionally, step B specifically includes: mixing activated carbon fibers, deionized water, polyoxypropylene diamine, and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate, and mixing at 90°C. o The reaction was maintained at C for 2 hours, and then the modified carbon fiber was obtained by separation.

[0010] Optionally, step C specifically includes: Iron carbonyl is provided, and after being treated with hydrochloric acid, it is added to deionized water and stirred to form a turbid liquid; An alcohol solution is provided, the alcohol solution comprising alcohol, tetraethyl orthosilicate and 3-aminopropyltriethoxysilane; The turbid liquid was mixed with the alcohol solution, and the resulting solution was heated at 40°C. o C. The reaction was carried out under stirring for 3 hours, and then purified to obtain carbonyl iron with silica coating, namely the coated carbonyl iron.

[0011] Optionally, step D specifically includes: adding the coated carbonyl iron into a reflux reflux maker, then adding toluene and 3-aminopropyltriethoxysilane, and refluxing at 110°C for 6 hours to obtain modified carbonyl iron.

[0012] Optionally, in step E, hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane are mixed uniformly in a molar ratio of (0.2-0.4):(0.1-0.3):9:10.

[0013] Optionally, step F specifically includes: adding 10 kg of the organosilicon resin to a mixing tank, followed by sequentially adding 2-3 kg of the modified carbon fiber and 8-12 kg of the modified carbonyl iron to the mixing tank, and then mixing at 150 °C. o Stirring at C for 2 hours yields an organosilicon resin mixture.

[0014] Optionally, in step G, the extrusion head of the extruder is a circular hole with a diameter of 0.5 mm.

[0015] Optionally, step H specifically includes: arranging the silicone resin rods neatly, and then... o C-shaped high thermal conductivity and microwave absorbing carbon fiber composite material is obtained by extrusion under C.

[0016] In a second aspect, the present invention provides a high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging, wherein the composite material is prepared by the method described herein.

[0017] A third aspect of the present invention provides an application of the high thermal conductivity and microwave absorbing carbon fiber composite material described herein in semiconductor packaging.

[0018] Beneficial effects: 1) By simultaneously adding carbon fiber and carbonyl iron to the silicone resin, the material possesses both excellent microwave absorption and thermal conductivity properties.

[0019] 2) Activation treatment with concentrated nitric acid is used to attach a large number of oxygen-containing functional groups to the surface of carbon fibers, thereby promoting the bonding between the carbon fiber surface and the oxygen-containing functional groups of the modifier.

[0020] This is because concentrated nitric acid has strong oxidizing properties and can partially oxidize carbon fibers under certain temperature and long-term reaction conditions, causing oxygen-containing functional groups to connect to the surface of the carbon fibers, which creates conditions for further activation and modification.

[0021] 3) The agglomeration problem of carbon fibers is effectively solved by using polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate for combined modification.

[0022] Polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate are rich in amino groups and polar sites, which can react with oxygen-containing functional groups on the surface of carbon fibers to form an organic coating layer, thereby effectively solving the problem of carbon fiber agglomeration.

[0023] 4) The dielectric properties of carbonyl iron can be effectively improved by coating the surface of carbonyl iron with silicon dioxide.

[0024] 5) 3-Aminopropyltriethoxysilane was used to modify carbonyl iron by reflux, which achieved a good modification effect on carbonyl iron and effectively solved the problem of carbonyl iron agglomeration.

[0025] 3-Aminopropyltriethoxysilane coats carbonyl iron, forming steric hindrance, thereby effectively preventing the aggregation of carbonyl iron.

[0026] 6) The round holes with matching apertures enable the carbon fibers to achieve good parallel alignment during the extrusion process; at the same time, there is no need to use large-scale equipment with electric or magnetic fields, and the safety risks of high-voltage electricity are also avoided.

[0027] 7) The stable silicon-oxygen bonds in silicone resins, when combined with darker colored composite materials, can effectively improve the material's resistance to yellowing and enhance its thermal stability. Detailed Implementation

[0028] This invention provides a high thermal conductivity, microwave-absorbing carbon fiber composite material for semiconductor packaging, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] Currently, there are still many technical problems with high thermal conductivity and microwave absorbing carbon fiber composite materials for potting high-power semiconductor devices in terms of high temperature resistance and pressure resistance. For example, it is difficult to simultaneously achieve good microwave absorption, thermal conductivity and certain insulation properties. The microwave absorbing material can have a negative impact on the orientation of carbon fibers. The high temperature resistance of carbon fibers after orientation is insufficient. When the device is stored at high temperature for a long time, the carbon fiber composite material is prone to yellowing, increased hardness or even cracking, and eventually loses its protective function for the device.

[0030] Therefore, the present invention provides a method for preparing a high thermal conductivity absorbing carbon fiber composite material for semiconductor packaging, aiming to solve the problems of low dielectric properties, poor resistance to yellowing, and poor thermal stability of existing high thermal conductivity absorbing carbon fiber composite materials for semiconductor packaging.

[0031] This invention addresses the problems of poor dielectric properties, insufficient resistance to yellowing, and inadequate thermal stability in high thermal conductivity carbon fiber composites used in semiconductor packaging by developing high-performance, high thermal conductivity carbon fiber absorbing composites. To further improve the high-temperature resistance and thermal stability of these composites, a carbon fiber orientation process and a more reliable resin are essential. The orientation of the carbon fibers imparts superior directional heat transfer properties, effectively dissipating heat into the surrounding air and extending the material's lifespan. However, the addition of microwave-absorbing materials to polymer materials can negatively impact the orientation of the carbon fibers; improper control of this can severely impair the overall performance of semiconductor devices.

[0032] Specifically, this invention provides a method for preparing a high thermal conductivity, microwave-absorbing carbon fiber composite material for semiconductor packaging, comprising the following steps: A. Provide carbon fibers in millimeter lengths and activate the carbon fibers using concentrated nitric acid; B. The activated carbon fibers were modified by using polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate to obtain modified carbon fibers. C. Provide carbonyl iron, and coat the surface of the carbonyl iron with silicon dioxide to obtain coated carbonyl iron; D. The coated carbonyl iron was modified by reflux using 3-aminopropyltriethoxysilane to obtain modified carbonyl iron; E. Mix hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane and side-chain vinyl polydimethylsiloxane to form an organosilicon resin. F. Mix the organosilicon resin, the modified carbon fiber, and the modified carbonyl iron, and stir to obtain an organosilicon resin mixture; G. The silicone resin mixture is extruded through an extruder, wherein the extrusion head of the extruder is a round hole, to obtain silicone resin round rods; H. The silicone resin rods are arranged neatly and extruded to obtain a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

[0033] The main technical advantages of this embodiment are as follows: 1) Oriented carbon fibers enable rapid heat transfer, giving the composite material excellent thermal conductivity.

[0034] 2) Carbonyl iron has good microwave absorption properties, which gives the composite material good microwave absorption properties.

[0035] 3) Carbonyl iron is coated with silica, and carbon fibers are also coated with organic matter, which improves the insulation performance of the composite material to a certain extent.

[0036] 4) The round holes with matching apertures enable the carbon fibers to achieve good parallel alignment during the extrusion process.

[0037] 5) The stable silicon-oxygen bonds in silicone resin, combined with the darker color of silicone resin, effectively improve the problems of insufficient resistance to yellowing and low thermal stability of the material.

[0038] In one embodiment, step A specifically includes: placing the carbon fiber in concentrated nitric acid with a mass fraction of 68% and soaking it at 80°C for 3-4 hours.

[0039] In one embodiment, step B specifically includes: mixing activated carbon fibers, deionized water, polyoxypropylene diamine, and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate, and mixing at 90°C. oThe reaction was maintained at C for 2 hours, and then the modified carbon fiber was obtained by separation.

[0040] The activated carbon fiber, deionized water, polyoxypropylene diamine, and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-hexafluorophosphate oxide can be added in the following proportions: for every 5-10 kg of activated carbon fiber, there are 150 kg of deionized water, 20 kg of polyoxypropylene diamine, and 20 g of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-hexafluorophosphate oxide.

[0041] The separation process may include: cooling the system to room temperature after the reaction is complete, and then performing pressure filtration on the cooled system to separate the solid and liquid phases to obtain modified carbon fibers.

[0042] In one implementation, step C specifically includes: Iron carbonyl is provided, and after being treated with hydrochloric acid, it is added to deionized water and stirred to form a turbid liquid; An alcohol solution is provided, the alcohol solution comprising alcohol, tetraethyl orthosilicate and 3-aminopropyltriethoxysilane; The turbid liquid was mixed with the alcohol solution, and the resulting solution was heated at 40°C. o C. The reaction was carried out under stirring for 3 hours, and then purified to obtain carbonyl iron with silica coating, namely the coated carbonyl iron.

[0043] The carbonyl iron can be powdered carbonyl iron, and the average particle size of the powdered carbonyl iron can be 7 μm.

[0044] The process of treating the carbonyl iron with hydrochloric acid may include: reacting the carbonyl iron with 0.02M hydrochloric acid under ultrasonic conditions for 5 minutes, followed by rinsing with deionized water.

[0045] The alcohol solution can be prepared by dissolving tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) in alcohol (i.e., ethanol), wherein the volume ratio of APTES:TEOS:ethanol is 1:3:2400, and stirring continuously to form the alcohol solution.

[0046] The volume ratio of the turbid liquid to the alcohol solution can be 1:4.

[0047] In one embodiment, step D specifically includes: adding the coated carbonyl iron into a reflux reflux maker, then adding toluene and 3-aminopropyltriethoxysilane, and refluxing at 110°C for 6 hours to obtain modified carbonyl iron.

[0048] The coated carbonyl iron and 3-aminopropyltriethoxysilane can be added in the following ratio: 45 kg of coated carbonyl iron powder corresponds to 45 L of 3-aminopropyltriethoxysilane.

[0049] In one embodiment, in step E, hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated dimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane are mixed uniformly in a molar ratio of (0.2-0.4):(0.1-0.3):9:10.

[0050] In one embodiment, step F specifically includes: adding 10 kg of the organosilicon resin to a mixing tank, followed by sequentially adding 2-3 kg of the modified carbon fiber and 8-12 kg of the modified carbonyl iron to the mixing tank, and then heating at 150 °C. o Stirring at C for 2 hours yields an organosilicon resin mixture.

[0051] In one embodiment, in step G, the extrusion head of the extruder is a circular hole with a diameter of 0.5 mm to ensure that the carbon fibers are arranged vertically.

[0052] In one embodiment, step H specifically includes: arranging the silicone resin rods neatly, and then... o C-shaped high thermal conductivity and microwave absorbing carbon fiber composite material is obtained by extrusion under C.

[0053] This invention provides a high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging, which is prepared by the method described above.

[0054] This invention provides an application of the high thermal conductivity and microwave absorbing carbon fiber composite material described above in semiconductor packaging.

[0055] The present invention will now be described in detail through several specific embodiments.

[0056] Example 1 1) Wash the carbon fibers, which are in the millimeter range in length, with clean water; 2) The above carbon fibers were placed in concentrated nitric acid with a mass fraction of 68% and soaked at 80°C for 3 hours; 3) Remove the carbon fiber and wash it with clean water; 4) Add 5 kg of carbon fiber to 150 kg of deionized water, along with 20 kg of polyoxypropylene diamine and 20 g of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate. Heat at 90 °C. o The reaction was maintained at C for 2 hours, and then cooled to room temperature. 5) After cooling, the system is filtered to separate the solid and liquid components. The separated modified carbon fibers are then placed in storage tank A for later use. 6) React 5 kg of carbonyl iron powder (average particle size 7 μm) with 0.02 M hydrochloric acid solution under ultrasonic conditions for 5 min, and then rinse 3 times with deionized water; 7) Add 50 kg of deionized water and stir continuously until it becomes cloudy, forming a turbid liquid; 8) Dissolve tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) in 400L of alcohol (i.e., ethanol), wherein the volume ratio of APTES:TEOS:ethanol is 1:3:2400, and stir continuously to form an alcohol solution. 9) Pour the above turbid liquid into the alcohol solution, with a volume ratio of turbid liquid to alcohol solution of 1:4; 10) Then place the mixed solution in a constant temperature environment, stirring constantly, at 40°C. o The reaction was maintained at C for 3 hours. 11) Filter using a fine-mesh filter cloth, then dry, grind, wash, and dry again to form coated carbonyl iron powder; 12) Add 45 kg of coated carbonyl iron powder to a 1000 L capacity reflux reflux maker, then add 300 L of toluene and 45 LAPTES, and reflux at 110 °C for 6 hours to form modified carbonyl iron powder. 13) Use a small-pore filter cloth to filter the modified carbonyl iron powder; 14) Wash the modified carbonyl iron powder with toluene and ethanol respectively, and then dry it; 15) Place the dried modified carbonyl iron powder into storage tank B; 16) The four polymers, namely hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane, are mixed evenly in a molar ratio of 0.2:0.1:9:10 to form silicone resin C. 17) Add 10 kg of silicone resin C to the mixing tank, then add 2 kg of modified carbon fiber from storage tank A and 8 kg of modified carbonyl iron powder from storage tank B in sequence, heat to 150°C and stir continuously. 18) The silicone resin mixture in the mixing tank is extruded through an extruder. The extrusion head of the extruder is a round hole with a diameter of 0.5 mm to ensure that the carbon fibers are vertically aligned. 19) Arrange the extruded silicone resin rods neatly; 20) The neatly arranged silicone resin rods are heated again to 100°C. o C, and extruded to form a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

[0057] Example 2 1) Wash the carbon fibers, which are in the millimeter range in length, with clean water; 2) The above carbon fibers were placed in concentrated nitric acid with a mass fraction of 68% and soaked at 80°C for 3 hours; 3) Remove the carbon fiber and wash it with clean water; 4) Add 7 kg of carbon fiber to 150 kg of deionized water, along with 20 kg of polyoxypropylene diamine and 20 g of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate. Heat at 90 °C. o The reaction was maintained at C for 2 hours, and then cooled to room temperature. 5) After cooling, the system is filtered to separate the solid and liquid components. The separated modified carbon fibers are then placed in storage tank A for later use. 6) React 7 kg of carbonyl iron powder (average particle size 7 μm) with 0.02 M hydrochloric acid solution under ultrasonic conditions for 5 min, and then rinse 3 times with deionized water; 7) Add 50g of deionized water and stir constantly until it becomes cloudy, forming a turbid liquid; 8) Dissolve tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) in 400L of alcohol (i.e., ethanol), wherein the volume ratio of APTES:TEOS:ethanol is 1:3:2400, and stir continuously to form an alcohol solution. 9) Pour the above turbid liquid into the alcohol solution, with a volume ratio of turbid liquid to alcohol solution of 1:4; 10) Then place the mixed solution in a constant temperature environment, stirring constantly, at 40°C. o The reaction was maintained at C for 3 hours. 11) Filter using a fine-mesh filter cloth, then dry, grind, wash, and dry again to form coated carbonyl iron powder; 12) Add 45 kg of coated carbonyl iron powder to a 1000 L capacity reflux reflux maker, then add 300 L of toluene and 45 LAPTES, and reflux at 110 °C for 6 hours to form modified carbonyl iron powder. 13) Use a small-pore filter cloth to filter the modified carbonyl iron powder; 14) Wash the modified carbonyl iron powder with toluene and ethanol respectively, and then dry it; 15) Place the dried modified carbonyl iron powder into storage tank B; 16) The four polymers, namely hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane, are mixed evenly in a molar ratio of 0.3:0.2:9:10 to form silicone resin C; 17) Add 10 kg of silicone resin C to the mixing tank, then add 3 kg of modified carbon fiber from storage tank A and 10 kg of modified carbonyl iron powder from storage tank B in sequence, heat to 150°C and stir continuously. 18) The silicone resin mixture in the mixing tank is extruded through an extruder. The extrusion head of the extruder is a round hole with a diameter of 0.5 mm to ensure that the carbon fibers are vertically aligned. 19) Arrange the extruded silicone resin rods neatly; 20) The neatly arranged silicone resin rods are heated again to 100°C. o C, and extruded to form a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

[0058] Example 3 1) Wash the carbon fibers, which are in the millimeter range in length, with clean water; 2) The above carbon fibers were placed in concentrated nitric acid with a mass fraction of 68% and soaked at 80°C for 3 hours; 3) Remove the carbon fiber and wash it with clean water; 4) Add 10 kg of carbon fiber to 150 kg of deionized water, along with 20 kg of polyoxypropylene diamine and 20 g of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate. Heat at 90 °C. o The reaction was maintained at C for 2 hours, and then cooled to room temperature. 5) After cooling, the system is filtered to separate the solid and liquid components. The separated modified carbon fibers are then placed in storage tank A for later use. 6) React 10 kg of carbonyl iron powder (average particle size 7 μm) with 0.02 M hydrochloric acid solution under ultrasonic conditions for 5 min, then rinse 3 times with deionized water. 7) Add 50 kg of deionized water and stir continuously until it becomes cloudy, forming a turbid liquid; 8) Dissolve tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) in 400L of alcohol (i.e., ethanol), wherein the volume ratio of APTES:TEOS:ethanol is 1:3:2400, and stir continuously to form an alcohol solution. 9) Pour the above turbid liquid into the alcohol solution, with a volume ratio of turbid liquid to alcohol solution of 1:4; 10) Then place the mixed solution in a constant temperature environment, stirring constantly, at 40°C. o The reaction was maintained at C for 3 hours. 11) Filter using a fine-mesh filter cloth, then dry, grind, wash, and dry again to form coated carbonyl iron powder; 12) Add 45 kg of coated carbonyl iron powder to a 1000 L capacity reflux reflux maker, then add 300 L of toluene and 45 LAPTES, and reflux at 110 °C for 6 hours to form modified carbonyl iron powder. 13) Use a small-pore filter cloth to filter the modified carbonyl iron powder; 14) Wash the modified carbonyl iron powder with toluene and ethanol respectively, and then dry it; 15) Place the dried modified carbonyl iron powder into storage tank B; 16) The four polymers, namely hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane, are mixed evenly in a molar ratio of 0.4:0.3:9:10 to form silicone resin C; 17) Add 10 kg of silicone resin C to the mixing tank, then add 3 kg of modified carbon fiber from storage tank A and 12 kg of modified carbonyl iron powder from storage tank B in sequence, heat to 150°C and stir continuously. 18) The silicone resin mixture in the mixing tank is extruded through an extruder. The extrusion head of the extruder is a round hole with a diameter of 0.5 mm to ensure that the carbon fibers are vertically aligned. 19) Arrange the extruded silicone resin rods neatly; 20) The neatly arranged silicone resin rods are heated again to 100°C. o C, and extruded to form a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

[0059] Comparative Example 1 It is basically the same as Example 1, except that: 2) Place the above carbon fibers in 50% concentrated nitric acid and soak them at 70°C for 3 hours; 4) Add 5 kg of carbon fiber to 150 kg of deionized water, along with 15 kg of polyoxypropylene diamine and 10 g of 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate. Heat at 80 °C. o The reaction was maintained at C for 2 hours, and then cooled to room temperature.

[0060] Comparative Example 2 It is basically the same as Example 1, except that: 8) Dissolve tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) in 400L of alcohol (i.e., ethanol), wherein the volume ratio of APTES:TEOS:ethanol is 0.5:1:2400, and stir continuously to form an alcohol solution.

[0061] The high thermal conductivity and microwave absorbing carbon fiber composite materials for semiconductor packaging prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0062] The yellowing resistance test was conducted according to GB / T 23983-2009 "Determination of Yellowing Resistance of Wood Coatings". A UVA-340 lamp was used to simulate solar ultraviolet radiation. Under conditions of 60℃±3℃, irradiance of 0.68W / m², and dryness without condensation, the carbon fiber composite material was continuously exposed to light for 168 hours. The yellowing resistance level was assessed by the color difference change (ΔE). The smaller the color difference value, the better the yellowing resistance.

[0063] Among them, the rubber aging performance test is based on GB / T 3512-2014 "Accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber in hot air". The hardness change is measured in a low air flow environment, and the tensile strength change is tested after aging at 120℃ for 70 hours.

[0064] As shown in Table 1, compared with Comparative Examples 1-2, the carbon fiber composite materials prepared in Examples 1-3 of this invention possess superior thermal conductivity and microwave absorption properties, and also exhibit a higher compression ratio and less change in tensile strength. The carbon fiber composite materials prepared in Examples 1-3 of this invention also possess excellent resistance to yellowing.

[0065] Table 1 Comprehensive properties of carbon fiber composites

[0066] In summary, the present invention provides a high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging, its preparation method and application. By simultaneously adding carbon fiber and carbonyl iron to organosilicon resin, the material possesses both good microwave absorption and thermal conductivity properties. The concentrated nitric acid activation treatment causes a large number of oxygen-containing functional groups to adhere to the carbon fiber surface, thereby promoting the bonding between the functional groups of the carbon fiber surface and the modifier. The co-modification of carbon fiber with polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate effectively solves the agglomeration problem of carbon fiber; coating the surface of carbonyl iron with silica effectively improves the dielectric properties of carbonyl iron; reflow modification of carbonyl iron with 3-aminopropyltriethoxysilane achieves good modification effect and effectively solves the agglomeration problem of carbonyl iron; the round pores with suitable pore size enable the carbon fiber to achieve good parallel alignment during extrusion; at the same time, it eliminates the need for large-scale equipment such as electric or magnetic fields and avoids the safety risks of high-voltage electricity; the stable silicon-oxygen bonds in the organosilicon resin, combined with the darker-colored composite material, can effectively improve the material's resistance to yellowing and enhance its thermal stability.

[0067] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a high thermal conductivity, microwave-absorbing carbon fiber composite material for semiconductor packaging, characterized in that, Includes the following steps: A. Provide carbon fibers in millimeter lengths and activate the carbon fibers using concentrated nitric acid; B. The activated carbon fibers were modified by using polyoxypropylene diamine and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate to obtain modified carbon fibers. C. Provide carbonyl iron, and coat the surface of the carbonyl iron with silicon dioxide to obtain coated carbonyl iron; D. The coated carbonyl iron was modified by reflux using 3-aminopropyltriethoxysilane to obtain modified carbonyl iron; E. Mix hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane and side-chain vinyl polydimethylsiloxane to form an organosilicon resin. F. Mix the organosilicon resin, the modified carbon fiber, and the modified carbonyl iron, and stir to obtain an organosilicon resin mixture; G. The silicone resin mixture is extruded through an extruder, wherein the extrusion head of the extruder is a round hole, to obtain silicone resin round rods; H. The silicone resin rods are arranged neatly and extruded to obtain a blocky high thermal conductivity and microwave absorbing carbon fiber composite material.

2. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, Step B specifically includes: mixing activated carbon fibers, deionized water, polyoxypropylene diamine, and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridine-3-oxyhexafluorophosphate, and heating at 90°C. o The reaction was maintained at C for 2 hours, and then the modified carbon fiber was obtained by separation.

3. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, Step C specifically includes: Iron carbonyl is provided, and after being treated with hydrochloric acid, it is added to deionized water and stirred to form a turbid liquid; An alcohol solution is provided, the alcohol solution comprising alcohol, tetraethyl orthosilicate and 3-aminopropyltriethoxysilane; The turbid liquid was mixed with the alcohol solution, and the resulting solution was heated at 40°C. o C. The reaction was carried out under stirring for 3 hours, and then purified to obtain carbonyl iron with silica coating, namely the coated carbonyl iron.

4. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, Step D specifically includes: adding the coated carbonyl iron into a reflux reflux maker, then adding toluene and 3-aminopropyltriethoxysilane, and refluxing at 110°C for 6 hours to obtain modified carbonyl iron.

5. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, In step E, hydroxyl-terminated polydimethylsiloxane, side-chain polyhydrogen-terminated polydimethylsiloxane, single-terminated hydrogen-terminated polydimethylsiloxane, and side-chain vinyl polydimethylsiloxane are mixed evenly in a molar ratio of (0.2-0.4):(0.1-0.3):9:

10.

6. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, Step F specifically includes: adding 10 kg of the organosilicon resin to a mixing tank, followed by sequentially adding 2-3 kg of the modified carbon fiber and 8-12 kg of the modified carbonyl iron to the mixing tank, and then heating at 150 °C. o Stirring at C for 2 hours yields an organosilicon resin mixture.

7. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, In step G, the extrusion head of the extruder is a circular hole with a diameter of 0.5 mm.

8. The method for preparing the high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging according to claim 1, characterized in that, Step H specifically includes: arranging the silicone resin rods neatly, and then... o C-shaped high thermal conductivity and microwave absorbing carbon fiber composite material is obtained by extrusion under C.

9. A high thermal conductivity, microwave-absorbing carbon fiber composite material for semiconductor packaging, characterized in that, It is prepared by the method of any one of claims 1-8 for preparing high thermal conductivity and microwave absorbing carbon fiber composite material for semiconductor packaging.

10. The application of the high thermal conductivity and microwave absorbing carbon fiber composite material of claim 9 in semiconductor packaging.

Images