Alumina fiber cloth and application thereof

Abstract

The invention provides alumina fiber cloth and application thereof. The alumina fiber cloth is composed of a plurality of alumina fiber filaments. The mass ratio of aluminum oxide in the aluminum oxide cellosilk is greater than or equal to 40%, and the balance is at least one of SiO2 and the like; the alumina fiber meets the following properties: (a) dielectric loss at 10GHz is less than or equal to 0.0015; (b) The weight bending stiffness per unit area in the warp direction is 0.0002 to 0.0015 gf * cm < 2 > / cm. The invention also provides application of the alumina fiber cloth in preparation of electronic equipment substrates. The alumina fiber cloth disclosed by the invention has excellent comprehensive performance, and an electronic material prepared from the alumina fiber cloth disclosed by the invention better meets the use requirements of the existing AI technology; in addition, due to excellent low dielectric loss, high dimensional stability and heat dissipation capability, the composite material can be used as an ideal reinforcing material of a key circuit substrate in a high-speed big data transmission optical module.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fibers, and particularly relates to an aluminum oxide fiber cloth and application thereof. BACKGROUND

[0002] With AI becoming the engine of the new round of technological revolution, AI products continue to expand from the cloud to the end side, accelerating the arrival of the era of "everything is AI". In this process, AI servers as key infrastructure bring significant value enhancement opportunities to the industry chain. Technically, AI servers have much higher requirements for printed circuit boards (PCB) than traditional servers, especially in high-frequency high-speed and high-power density scenarios, which put extremely strict requirements on the technical indicators of low loss (such as low dielectric loss Df and low dielectric constant Dk), high thermal conductivity, and low coefficient of thermal expansion (CTE) of PCB materials. Currently, the high-speed copper-clad board material used in AI server PCB has been upgraded to M7, M8, or even M9 level, and the core insulating materials of which mainly include E-Glass, Ne-Glass, Low-Dk Glass, D-Glass, etc.

[0003] To reduce the dielectric properties of insulating materials, the prior art usually uses low-loss glass fibers (such as Ne-Glass, Low-Dk Glass, D-Glass, etc.) to impregnate thermosetting resin and inorganic fillers to make a semi-cured sheet, which is then laminated with a metal foil to form a copper-clad board (CCL) and finally applied to PCB manufacturing.

[0004] However, the PCB materials based on the above-mentioned traditional glass fibers such as E-Glass, Ne-Glass, Low-Dk Glass, and D-Glass have obvious limitations in meeting the core needs of AI servers and other ultra-high flux PCBs: the key performance indicators such as low dielectric loss (Df), low dielectric constant (Dk), high thermal conductivity, and low CTE are still difficult to fully meet the stringent standards of the next generation of AI hardware.

[0005] A particularly prominent problem is that the CTE of existing PCB substrates is significantly different from that of high-performance AI chips. This mismatch generates a huge thermal expansion stress between materials during the chip mounting (SMT) process and when the chip is running at high load, which directly leads to reliability failure problems such as solder joint cracking, substrate warping, and even chip delamination, seriously affecting the yield and long-term stability of the product. Therefore, developing new high-performance reinforced fiber materials to fundamentally solve the above-mentioned bottlenecks has become an urgent need in the field. SUMMARY

[0006] To solve the above problems, first, the application provides an alumina fiber cloth, which has excellent comprehensive performance, including extremely low dielectric constant (Dk) and dielectric loss (Df), excellent thermal conductivity and extremely low and more matched thermal expansion coefficient (CTE) with chips, can effectively solve the core challenges of high-frequency high-speed signal integrity, heat dissipation efficiency and thermal mechanical reliability of AI server PCB, and with excellent low dielectric loss, high dimensional stability and heat dissipation capacity, becomes an ideal reinforcing material for key circuit substrate in high-speed big data transmission optical module.

[0007] The alumina fiber cloth is formed by a plurality of alumina fiber filaments, and the mass fraction of alumina (Al2O3) in the alumina fiber filaments is ≥40%, and the remaining components are at least one of SiO2, CaO, B2O3, MgO, K2O, Na2O and TiO2.

[0008] The alumina fiber filaments meet the following performance: (a) dielectric loss ≤0.0015 at 10 GHz; (b) unit area weight bending stiffness of the filament direction is 0.0002-0.0015 gf·cm 2 / cm.

[0009] Preferably, the mass fraction of alumina in the alumina fiber filaments is 50%-100%; more preferably, the mass fraction of alumina in the alumina fiber filaments is 90%-100%; most preferably, the mass fraction of alumina in the alumina fiber filaments is 99.6%-100%. In the alumina fiber filaments used in the application, alumina (Al2O3) is the main material component, and the mass fraction thereof needs to be ≥40%. By using such alumina fiber filaments, the dielectric properties of the obtained alumina fiber cloth can be improved.

[0010] Preferably, the alumina fiber filaments are surface treated, and the surface treatment agent of the surface treatment contains one or more silane coupling agents; starting from the fact that it is not easy to hinder the reaction of alumina fiber filaments with resin, more preferably, the silane coupling agent is non-ionic and has at least one functional group of vinyl, methacryloyloxy or acryloyloxy; most preferably, the silane coupling agent has at least one methacryloyloxy or acryloyloxy. By the above surface treatment agent containing a silane coupling agent, the reaction of alumina fiber filaments with resin is not hindered, and the heat resistance and reliability of the printed circuit board are improved.

[0011] Preferably, the surface treatment further comprises acid-base etching treatment: acid treatment with a hydrochloric acid or sulfuric acid solution having a concentration of 1-60% by mass / volume for 0.1-10 hours to form a micron-scale roughness; or alkali treatment with a sodium hydroxide solution having a concentration of 1-60% by mass / volume for 0.1-10 hours to form a flaky nanostructure layer. The alumina fiber filaments are subjected to acid-base etching treatment, and the interfacial bonding strength is increased by 1-60%. Note that the acid-base concentration and treatment time are selected to avoid loss of fiber strength.

[0012] Preferably, the surface treatment further comprises plasma treatment. High-energy ion bombardment of the surface of the alumina fiber filaments achieves both physical and chemical modification, increases the surface roughness of the alumina fiber filaments, forms a mechanical interlocking structure, and enhances the chemical bonding strength with the resin.

[0013] Preferably, the average filament diameter of the alumina fiber filaments is 2.5-9.0 μm. When the filament diameter of the alumina fiber filaments is less than 2.5 μm, the breaking strength of the filaments is low, and the obtained alumina fiber cloth is prone to produce fluff. When the filament diameter of the alumina fiber filaments exceeds 9.0 μm, the mass of the alumina fiber filaments is large, and it is difficult to transport and process the alumina fiber filaments.

[0014] Preferably, the warp filament density and the weft filament density of the alumina fiber cloth are independently 10-150 filaments / inch; more preferably, the warp filament density and the weft filament density of the alumina fiber cloth are independently 30-100 filaments / inch.

[0015] Preferably, the unit area weight of the alumina fiber cloth is 8-250 g / m 2 ; more preferably, the unit area weight of the alumina fiber cloth is 8-80 g / m 2 ; most preferably, the unit area weight of the alumina fiber cloth is 8-50 g / m 2 .

[0016] Preferably, the thickness of the alumina fiber cloth is 200 μm or less; more preferably, the thickness of the alumina fiber cloth is 100 μm or less; most preferably, the thickness of the alumina fiber cloth is 50 μm or less.

[0017] Preferably, the coefficient of variation of the unit area weight (g / m 2 ) of the alumina fiber cloth is 5% or less. Thus, on the basis of being able to inhibit variation in the unit area weight, the alumina fiber cloth also has excellent dielectric properties (e.g., low dielectric loss, low dielectric constant).

[0018] Preferably, the alumina fiber cloth is woven by weaving the alumina fiber yarns as warp and weft, and the weaving can be plain weave, basket weave, satin weave, twill weave, or the like. More preferably, the weaving is plain weave.

[0019] Secondly, the present application provides the use of the above alumina fiber cloth in the preparation of electronic device substrates.

[0020] Thirdly, the present application provides a prepreg comprising the above alumina fiber cloth, a base resin, and an inorganic filler. The alumina fiber cloth is impregnated in the base resin, and the prepreg thus obtained has few voids.

[0021] The base resin comprises at least one of a thermosetting resin and a thermoplastic resin, and can further comprise other resins; preferably, the base resin is a thermosetting resin.

[0022] The thermosetting resin includes, but is not limited to, the following:

[0023] (a) an epoxy resin, which is cured by reacting 1) a compound having an epoxy group, with 2) a compound having at least one functional group selected from the group consisting of an amino group, a phenolic group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, and a hydroxyl group;

[0024] (b) a radical polymerization type curing resin, which is cured by reacting a compound having at least one functional group selected from the group consisting of an allyl group, a methacrylic acid group, and an acrylic acid group;

[0025] (c) a maleimide triazine resin, which is cured by reacting a compound having a cyanate group with a compound having a maleimide group;

[0026] (d) a thermally curable polyimide resin, which is cured by reacting a maleimide compound with an amine compound;

[0027] (e) a benzoxazine resin, which is crosslinked and cured by heating a compound having a benzoxazine ring.

[0028] It should be noted that, in the preparation of the (a) epoxy resin, the compounds can be reacted in the absence of a catalyst, or a catalyst having a reaction catalytic ability, such as an imidazole compound, a tertiary amine compound, a urea compound, and a phosphorus compound, can be added to the compounds to be reacted. In addition, in the preparation of the (b) radical polymerization type curing resin, a thermal decomposition type catalyst or a photodecomposition type catalyst can be used as a reaction initiator.

[0029] The thermoplastic resin includes, but is not limited to, at least one of polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, polyamide-imide, and fluororesin. The thermoplastic resin has sufficient radical reactivity and is more suitable as an insulating material for a printed circuit board for high-speed communication. Preferably, the thermoplastic resin is polyphenylene ether or modified polyphenylene ether.

[0030] The inorganic filler includes, but is not limited to, at least one of aluminum nitride, boron nitride, silicon nitride, aluminum hydroxide, zirconium oxide, calcium carbonate, aluminum oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silicon dioxide, talc, glass short fiber, aluminum borate, silicon carbide.

[0031] The prepreg is prepared by impregnating or coating the base resin and the inorganic filler on the alumina fiber cloth and drying.

[0032] Fourthly, the present application provides a copper-clad plate prepared by combining the above prepreg with a metal foil.

[0033] Fifthly, the present application provides a printed circuit board comprising the above copper-clad plate. The printed circuit board can be formed by patterning the outer metal of the copper-clad plate, or by patterning the outer metal of the copper-clad plate and then laminating and hot-pressing the prepreg and the metal foil.

[0034] Sixthly, the present application provides an integrated circuit comprising the above printed circuit board.

[0035] Seventhly, the present application provides an electronic device comprising the above printed circuit board.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1. The alumina fiber cloth of the present application has excellent comprehensive performance, including extremely low dielectric constant (Dk) and dielectric loss (Df), excellent thermal conductivity, and extremely low and more chip-matched thermal expansion coefficient (Z-CTE), which can effectively solve the core challenges of high-frequency high-speed signal integrity, heat dissipation efficiency, and thermal mechanical reliability of AI server PCB. The electronic material prepared from the alumina fiber cloth of the present application has good local glass transition temperature (Tg), thermal expansion coefficient (Z-CTE), heat resistance, electrical properties, electrical properties after moisture absorption, dimensional stability, processability, etc., especially the CTE stability and loss characteristics, which make it more meet the use requirements of existing AI technology.

[0038] 2、In addition, the alumina fiber of the present application has excellent low dielectric loss, high dimensional stability and heat dissipation capacity, and can also be used as an ideal reinforcing material for a key circuit substrate in a high-speed large data transmission optical module, thereby meeting the stringent requirements of the optical communication field for low loss and high stability of signals. DETAILED DESCRIPTION

[0039] The present application will be further described in conjunction with specific examples, which are not intended to limit the present application, but to illustrate the present application. The experimental methods used in the following examples are not specifically described, and the experimental methods not specifically described in the examples are generally performed under conventional conditions. The materials and reagents used in the following examples are commercially available unless otherwise specified.

[0040] EXAMPLE

[0041] The alumina fiber is woven into an alumina fiber cloth, the mass fraction of alumina (Al2O3) in the alumina fiber yarn is ≥40%, and the remaining components are at least one of SiO2, CaO, B2O3, MgO, K2O, Na2O and TiO2; the alumina fiber yarn satisfies the following properties: (a) dielectric loss ≤0.0015 at 10 GHz; (b) unit area weight bending stiffness in the yarn direction is 0.0002-0.0015 gf·cm 2 / cm; the average filament diameter of the alumina fiber yarn is 2.5-9.0 μm.

[0042] The alumina fiber yarn is surface treated, and the surface treatment agent of the surface treatment contains one or more silane coupling agents.

[0043] The surface treatment further includes acid and alkali etching treatment: acid treatment with a hydrochloric acid or sulfuric acid solution having a concentration of 1-60% by mass for 0.1-10 h to form a micron-level roughness; or alkali treatment with a sodium hydroxide solution having a concentration of 1-60% by mass for 0.1-10 h to form a sheet-like nanostructure layer.

[0044] The surface treatment further includes plasma treatment.

[0045] The warp density and weft density of the alumina fiber cloth are independently 10-150 yarns / inch. The unit area weight of the alumina fiber cloth is 8-250 g / m 2 . The thickness of the alumina fiber cloth is 200 μm or less. The coefficient of variation of the unit area weight (g / m2) of the alumina fiber cloth is 5% or less. The alumina fiber cloth is woven by weaving the alumina fiber yarn as warp and weft, and the weaving can be plain weave, basket weave, satin weave, twill weave, etc.

[0046] The prepreg is prepared by coating a base resin, an inorganic filler on the alumina fiber cloth, and drying. The base resin includes at least one of a thermosetting resin and a thermoplastic resin, and can further include other resins.

[0047] Thermosetting epoxy resin source: 50 parts by mass of biphenyl type epoxy resin (Mitsubishi Chemical NC-3000), 30 parts by mass of phenolic epoxy resin (DIC N-865), 20 parts by mass of cyanate ester resin (Lonza PT-30) were added to a reaction kettle, stirred and mixed at 80°C for 30 minutes; 0.5 parts by mass of 2-ethyl-4-methylimidazole (2E4MZ) was added, and stirring was continued at 60°C for 20 minutes; spherical silica (Admatec SO-E2, average particle size 0.5 μm) was treated with a high-speed disperser at 3000 rpm for 1 hour to remove agglomeration, to obtain a thermosetting epoxy resin.

[0048] Thermoplastic resin source: poly 2,6-dimethyl-1,4-phenylene ether (Asahi Kasei Corporation, XYRON S201A)

[0049] The copper-clad plates of Examples 1-13 and Comparative Examples 1-7 were prepared by laminating the prepregs prepared in Examples 1-13 and Comparative Examples 1-7 with metal foils.

[0050] The printed circuit boards of Examples 1-13 and Comparative Examples 1-7 were prepared by patterning the outer metal of the copper-clad plates of Examples 1-13 and Comparative Examples 1-7.

[0051] The printed circuit boards of Examples 1-13 and Comparative Examples 1-7 were used to prepare circuit substrates for AI servers and circuit substrates for large data transmission optical modules, respectively.

[0052] The circuit substrates for AI servers were used to produce AI servers.

[0053] The circuit substrates for large data transmission optical modules were used to produce large data transmission optical modules.

[0054] The specific components, amounts, processing methods and conditions in Examples 1-13 are shown in Table 1.

[0055]

[0056]

[0057]

[0058]

[0059] Comparative Example

[0060] The specific components and their amounts, treatment methods and condition parameters in Comparative Examples 1-7 are shown in Table 2.

[0061] Table 2

[0062]

[0063]

[0064] Effect Examples

[0065] The alumina fiber cloth, prepreg, copper-clad plate, and printed circuit board prepared in Examples 1-13 and Comparative Examples 1-7 were subjected to the following performance tests.

[0066] 1. Glass transition temperature (Tg) test

[0067] The laminated board for evaluation was subjected to etching to remove the copper foils on both sides thereof, and the resulting cladless board was subjected to measurement of glass transition temperature (Tg) using a thermomechanical analyzer (TMA). The test specification for glass transition temperature was IPC-TM-650.2.4.24C of The Institute for Interconnecting and Packaging Electronic Circuits (IPC).

[0068] 2. Measurement of coefficient of thermal expansion (Z-CTE)

[0069] The coefficient of thermal expansion (z-CTE) in the Z-axis direction (thickness direction) of the completely cured thermosetting resin composition was measured using a thermomechanical analyzer (TMA). The test was performed as follows: a 5 mm x 5 mm x 1.5 mm completely cured thermosetting resin composition was prepared as a test sample, and a thermomechanical analysis was performed on the test sample in the expansion / compression mode under conditions of a starting temperature of 30°C, an ending temperature of 330°C, a temperature increase rate of 10°C / min, and a load of 0.05 Newton (N), and the thermal expansion amount per 1°C in the temperature range of 30°C to 330°C was measured and averaged. The z-CTE was expressed in units of (ppm / °C).

[0070] 3. Tearing strength test

[0071] The tearing strength refers to the adhesion of a metal foil to a prepreg subjected to hot press lamination, and a 1 / 8-inch wide copper foil (0.5 ounce) was vertically torn from the surface of the board, and the strength of the adhesion was expressed in terms of the amount of force required. The unit of the tearing strength was pound force / inch (lbf / in).

[0072] 4. Heat resistance test

[0073] According to the IPC-TM-650 2.4.24.1 specification, the metal foil laminate was immersed in a 288°C tin furnace, and the time (s) required for the board to explode was recorded.

[0074] 5. Dimensional stability test

[0075] Four prepreg layers were laminated to prepare the sample to be tested. According to the IPC-TM-650 2.4.24.5 specification, the coefficient of thermal expansion (CTE) a1 of the sample to be tested at a temperature below Tg and the coefficient of thermal expansion change rate (total z-CTE) in the Z-axis direction were measured using a thermal mechanical analyzer (TMA). a1 was measured in the temperature range of 50°C to 120°C, and the unit was ppm / °C. The total z-CTE was measured in the temperature range of 50°C to 260°C, and the unit was %.

[0076] 6. Warpage test

[0077] According to the IPC TM-650-2.4.22 specification, the metal foil laminate was single-sided etched, the warpage phenomenon of the laminate was observed, and the warpage rate (%) was calculated.

[0078] 7. Filling test

[0079] The resin flow was tested. A prepreg was provided by impregnating a 1037 glass fiber cloth with a resin composition. The prepreg was laminated in the order of steel plate / copper foil / prepreg / patterned steel plate / copper foil / steel plate, and then placed in a press. After hot pressing at a temperature of 210±5°C, a surface pressure of 39 kg, and a temperature rise rate of 2.5°C / min for 120 min, the patterned steel plate was removed and cooled to room temperature. The ratio of the total number of filled holes was calculated: (total number of filled holes / total number of holes) x 100%.

[0080] 8. Flame resistance test

[0081] Using the UL 94V: Vertical Burning Test Method, the metal foil laminate was fixed in a vertical position and burned with a Bunsen burner. The self-extinguishing and combustion-supporting properties were compared. The ranking of flame resistance was: VO > V1 > V2.

[0082] 9. Measurement of dielectric constant (Dk) and dielectric loss (Df)

[0083] The dielectric constant (Dk) and dielectric loss factor (Df) were calculated using a split post dielectric resonator (SPDR) at a working frequency of 10 GHz according to the IPC-TM-650 2.5.5.13 specification. The resin content (Rc) of the prepreg used for testing was 55%.

[0084] 10. Measurement of dielectric constant (Dk) and dielectric loss (Df) after moisture absorption

[0085] The dielectric constant (Dk) and dielectric loss factor (Df) after moisture absorption were measured using the aforementioned methods after 5 hours of standing at 121 °C and 2 atmospheres of pressure using a pressure cooker test.

[0086] The performance test results of the aluminum oxide fiber cloth, prepreg, copper-clad plate, and printed circuit board prepared in Examples 1-13 are shown in Table 3.

[0087]

[0088]

[0089]

[0090] The effect data of Example 1 demonstrates its great advantages as an AI server PCB substrate reinforcing material: the extremely low Z-CTE (38 ppm / °C) can match the chip and reduce thermal stress; the low Df (0.0018) meets the high-speed signal transmission; the high Tg (185 °C) and excellent heat resistance (> 120 s) guarantee the reliability; the low warpage (0.05%) and high glue filling (99%) reflect the excellent processing stability.

[0091] The above Examples 1-13 and Comparative Examples 1-7 prove that: when the mass fraction of aluminum oxide in the aluminum oxide fiber yarn is less than 40%, the obtained aluminum oxide fiber cloth does not have the characteristics of low CTE, low loss, and high reliability (Comparative Example 1); when the Df of the aluminum oxide fiber yarn is ≤0.0015, the signal integrity of the final circuit board at high frequency is ensured (Comparative Example 2); when the yarn direction unit area weight bending stiffness of the aluminum oxide fiber yarn is 0.0002-0.0015 gf·cm 2 / cm, the processing and the flatness of the final product are balanced in the best parameter range (Comparative Examples 3 and 4); when the average filament diameter of the aluminum oxide fiber yarn is less than 2.5 or greater than 9.0 μm, the processing of the fiber cloth and the reliability of the final composite material will be negatively affected (Comparative Examples 5 and 6); when the unit area weight (g / m 2) of 5% or less is one of the important conditions for ensuring the production of high performance, high consistency of industrial products (Comparative Example 7).

[0092] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the scope of protection of the present application.

Claims

1. An alumina fiber cloth, characterized in that, It is composed of several alumina fiber filaments; the mass percentage of alumina (Al2O3) in the alumina fiber filaments is ≥40%, and the remaining components are at least one of SiO2, CaO, B2O3, MgO, K2O, Na2O, and TiO2; The alumina fiber filaments meet the following properties: (a) dielectric loss ≤ 0.0015 at 10 GHz; (b) bending stiffness per unit area weight in the warp direction is 0.0002~0.0015 gf·cm. 2 / cm.

2. The alumina fiber cloth according to claim 1, characterized in that, Includes at least one of the following (1)-(3): (1) The mass percentage of alumina in the alumina fiber is 50% to 100%; (2) The alumina fiber is surface treated, and the surface treatment agent contains one or more silane coupling agents. (3) The average diameter of the alumina fiber is 2.5 to 9.0 μm.

3. The alumina fiber cloth according to claim 2, characterized in that, Includes at least one of the following items (1)-(4): (1) The mass percentage of alumina in the alumina fiber is 90% to 100%; (2) The silane coupling agent is nonionic and has at least one functional group selected from vinyl, methacryloxy or acryloyloxy; (3) The surface treatment also includes acid and alkali etching: acid treatment with hydrochloric acid or sulfuric acid solution with a concentration of 1% to 60% by mass volume for 0.1 to 10 hours to form micron-level roughness; or alkali treatment with sodium hydroxide solution with a concentration of 1% to 60% by mass volume for 0.1 to 10 hours to form a sheet-like nanostructure layer. (4) The surface treatment also includes plasma treatment.

4. The alumina fiber cloth according to claim 3, characterized in that, Includes at least one of the following (1)-(2): (1) The mass percentage of alumina in the alumina fiber is 99.6% to 100%; (2) The silane coupling agent has at least one methacryloyloxy group or acryloyloxy group.

5. The alumina fiber cloth according to claim 1, characterized in that, Includes at least one of the following (1)-(5): (1) The warp and weft density of the alumina fiber cloth are independently 10 to 150 threads / inch; (2) The unit area weight of the alumina fiber cloth is 8-250 g / m². 2 ; (3) The thickness of the alumina fiber cloth is less than 200 μm; (4) The coefficient of variation of the unit area weight of the alumina fiber cloth is less than 5%; (5) The alumina fiber cloth is woven by using the alumina fiber filaments as warp and weft filaments. The weaving is to weave the alumina fiber cloth into plain weave, basket weave, satin weave, twill weave and other weaving structures.

6. The alumina fiber cloth according to claim 5, characterized in that, Includes at least one of the following (1)-(4): (1) The warp density and weft density of the alumina fiber cloth are independently 30 to 100 threads / inch; (2) The unit area weight of the alumina fiber cloth is 8-80 g / m². 2 ; (3) The thickness of the alumina fiber cloth is less than 100 μm; (4) The weaving is to weave the alumina fiber cloth into a plain weave structure.

7. A semi-cured sheet, characterized in that, The alumina fiber cloth, the base resin, and the inorganic filler according to any one of claims 1-6, further comprising at least one of the following (1)-(2): (1) The base resin includes at least one of thermosetting resin and thermoplastic resin; (2) The inorganic filler includes, but is not limited to, at least one of aluminum nitride, boron nitride, silicon nitride, aluminum hydroxide, zirconium oxide, calcium carbonate, aluminum oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silicon dioxide, talc, glass short fiber, aluminum borate, and silicon carbide.

8. A copper-clad laminate, characterized in that, It is prepared by combining the prepreg of claim 7 with a metal foil.

9. A printed circuit board, characterized in that, It includes the copper-clad laminate of claim 8.

10. An integrated circuit, characterized in that, It includes the printed circuit board of claim 9.

11. An electronic device, characterized in that, It includes the printed circuit board of claim 9.

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