Borosilicate-nano aerogel composite low-dielectric glass fiber and preparation method thereof

Abstract

The invention discloses borosilicate-nano aerogel composite low-dielectric glass fibers and a preparation method thereof, and belongs to the technical field of electronic glass fibers, and through compounding and synergy of nano aerogel and low-polarity borosilicate glass, the dielectric constant is reduced to 2.8-3.2 (1MHz), and the signal transmission loss is remarkably reduced. The silane coupling agent modifies and improves the bonding strength and the tensile strength of the aerogel-glass interface. The dispersion particle size of the aerogel is reduced through ultrasonic dispersion ball-milling pretreatment, and brittle fracture caused by stress concentration is avoided. Compared with the traditional melting process, the sol-gel method combined with the stepped heat treatment has the advantages that the energy consumption is reduced by 60-65%, a glass fiber solution with ultralow dielectric and high reliability is provided for a new generation of high-frequency and high-speed electronic devices, and the method has remarkable industrial application value.

Description

Technical Field

[0001] This invention relates to the field of electronic glass fiber technology, and in particular to a borosilicate-nano aerogel composite glass fiber with ultra-low dielectric constant and high mechanical strength and its low-temperature integrated preparation method, which is suitable for 5G / 6G high-frequency communication substrates, spacecraft wave-transparent windows and flexible electronic devices. Background Technology

[0002] Electronic glass fiber is a fundamental raw material for industries such as electronics, information technology, and aerospace. It appears in almost every electronic component and is found in all sectors of the national economy and defense industry. Electronic glass fiber cloth, woven from electronic glass fiber, is an essential material for the copper clad laminate (CCL) and printed circuit board (PCB) industries. Its properties largely determine the electrical, mechanical, and dimensional stability of CCL and PCB.

[0003] Since the beginning of the 21st century, the rapid development of communication equipment and mobile terminals, along with the need for big data technology, has spurred the development of the fifth-generation (5G) communication industry. On the PCB circuit boards of 5G communication integrated circuits, if existing electronic-grade glass fiber is used, its relatively high dielectric constant (approximately 6 or 7) will severely reduce the electromagnetic signal transmission rate and lead to significant dielectric loss. This causes some of the signal to be converted into heat energy during transmission, reducing signal strength and ultimately limiting the switching speed and transmission efficiency of high-frequency electrical signals on the PCB, failing to meet the requirements of the next-generation electronic information technology industry.

[0004] Currently, the glass fibers used in 5G / 6G communication base stations mainly employ E-glass or low-dielectric modified D-glass. However, these materials have the following inherent defects: Insufficient dielectric properties: E-glass fiber has a dielectric constant ε>5.0 at 10GHz, and D-glass can reduce ε to 4.2-4.5 by introducing fluorides, but it still cannot meet the future terahertz band requirement of ε<3.5; Significant high-frequency loss: Due to the polarization relaxation of free oxygen ions in the glass network, the loss tangent tanδ of traditional glass fiber in the frequency band above 30GHz is >0.005, resulting in a signal transmission efficiency decrease of more than 15%; Compromise in mechanical properties: Some studies have reduced the dielectric constant by increasing the B2O3 content, but excessive B2O3 (>25%) will cause the glass network to become porous, and the bending strength will drop from 1200MPa to below 600MPa.

[0005] Silica aerogel is considered an ideal candidate material due to its ultra-low dielectric constant (ε=1.1-2.0), but its standalone fiberization has serious drawbacks: low mechanical strength: the flexural strength of pure aerogel fibers is generally <200MPa, and the brittleness index is as high as 3.5×10⁻⁶. 3 J / m3 It cannot meet the processing requirements of substrate materials; poor environmental stability: the nanoporous structure easily absorbs moisture, causing the dielectric loss tanδ to rise to above 0.01; high temperature preparation problem: the traditional glass fiber drawing process requires a temperature above 1200℃, while aerogels undergo skeleton sintering at >800℃, losing low dielectric properties.

[0006] Therefore, there is still a lack of ultra-low dielectric glass fibers that can be used at high frequencies, while maintaining dielectric properties and mechanical strength. Summary of the Invention

[0007] This invention addresses the problem that the dielectric properties of existing low-dielectric glass fibers cannot meet the requirements of next-generation electronic information and communication technologies, and provides a borosilicate-nano aerogel composite glass fiber with ultra-low dielectric constant and high mechanical strength, as well as its low-temperature integrated preparation method.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] The first objective of this invention is to provide a borosilicate-nanoaerogel composite low-dielectric glass fiber, comprising a borosilicate glass matrix and nanoaerogel particles dispersed therein; the borosilicate glass matrix has the following mass percentages: SiO2 55-75%, B2O3 15-25%; and the aerogel volume fraction is 10-30%.

[0010] Preferably, the nano-aerogel is a silica aerogel or a silicon carbide aerogel, with an average pore size of 10-50 nm, a porosity ≥80%, and a density ≤0.1 g / cm³. 3 .

[0011] The second objective of this invention is to provide a method for preparing borosilicate-nano aerogel composite low-dielectric glass fibers, specifically including the following steps:

[0012] (1) Aerogel pretreatment: The aerogel was ultrasonically treated, dried and then ball-milled;

[0013] (2) Preparation of borosilicate sol: Tetraethyl orthosilicate and trimethyl borate were dissolved in ethanol solution, and the pH was adjusted with hydrochloric acid to form borosilicate sol;

[0014] (3) Composite dispersion: The pretreated aerogel and silane coupling agent are added to the sol and ultrasonically dispersed;

[0015] (4) Spinning and forming: Fiber filaments are prepared by centrifugal spinning;

[0016] (5) Step-by-step heat treatment: The fiber filaments in step (4) are heat-treated in stages to remove solvent, gel-transform and dynamically sinter to obtain composite fibers.

[0017] Preferably, the ultrasonic treatment in step (1) involves immersion in a 5-15% H2O2 solution for 1-3 hours.

[0018] Preferably, in step (2), ethyl silicate and trimethyl borate are mixed at a ratio of 60-75 wt%: 15-25 wt%.

[0019] Preferably, in step (2), the hydrochloric acid is used to adjust the pH range to 2.5-3.5, the reaction temperature is 50-70℃, and the aging time is 12-36h.

[0020] Preferably, the amount of pretreated aerogel added in step (3) is 10-30 vol%, and the amount of silane coupling agent is 1-5 wt%; the silane coupling agent is at least one of γ-aminopropyltriethoxysilane (KH-550) or γ-glycidoxypropyltrimethoxysilane (KH-560).

[0021] Preferably, the ultrasonic dispersion step in step (3) is performed with an ultrasonic power of 30-50 kHz and a dispersion time of 60-120 min.

[0022] Preferably, the rotation speed of the centrifugal spinning in step (4) is 2000-5000 rpm.

[0023] Preferably, the specific steps of the stepped heat treatment in step (5) are as follows: solvent removal stage: vacuum drying at 40-60℃ for 2-4 hours, and atmospheric pressure drying at 80-100℃ for 1-3 hours; gel conversion stage: 300-400℃ for 2-4 hours; sintering stage: heating at 3-8℃ / min to 600-700℃ and holding for 0.5-2 hours, and then cooling at 2-5℃ / min to 500-600℃ and holding for 0.5-1 hours.

[0024] Beneficial effects

[0025] This invention achieves synergistic optimization of dielectric and mechanical properties through innovative material design and low-temperature integrated process, successfully overcoming the long-standing contradiction of "low dielectric - high brittleness" in the field of low dielectric materials. Through the composite synergy of nano-aerogel and low-polarity borosilicate glass, the dielectric constant is reduced to 2.8-3.2 (1MHz), which is 53-59% lower than that of traditional E-glass fiber (ε≈6.8), meeting the stringent requirements of 5G / 6G communication for substrate materials with ε<3.5.

[0026] Silane coupling agent modification enhances the aerogel-glass interface bonding strength to 1.4-1.8 GPa and tensile strength to 1.8-2.2 GPa. Ultrasonic dispersion combined with ball milling pretreatment ensures aerogel particle size ≤200 nm, preventing brittle fracture caused by stress concentration. The sol-gel method combined with stepped heat treatment (up to 700℃) reduces energy consumption by 60-65% compared to traditional melting processes (>1500℃), providing a glass fiber solution with ultra-low dielectric and high reliability for next-generation high-frequency and high-speed electronic devices, demonstrating significant industrial application value. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments thereof.

[0028] Example 1

[0029] A borosilicate-nano aerogel composite low dielectric glass fiber

[0030] The specific preparation steps are as follows:

[0031] 1. Aerogel pretreatment: Commercial SiO2 aerogel (porosity 92%) was treated with 10% H2O2 for 1.5 h and then ball-milled to D50 = 180 nm.

[0032] 2. Sol preparation: Tetraethyl orthosilicate:trimethyl borate = 70:20 (wt%), ethanol solvent, pH = 3.2

[0033] 3. Composite dispersion: Add 25 vol% pretreated aerogel and 3 wt% KH-560, and disperse by ultrasonication at 40 kHz for 75 min.

[0034] 4. Spinning and drying: Centrifugal spinning (4000 rpm), gradient drying: 50℃ / -0.08MPa×3h→90℃×1.5h.

[0035] 5. Stage heat treatment: 80℃ / 2h→350℃ / 1h→650℃ / 2h (N2 protection, heating rate 5℃ / min).

[0036] Example 2

[0037] A borosilicate-nano aerogel composite low dielectric glass fiber

[0038] The specific preparation steps are as follows:

[0039] 1. Aerogel pretreatment: Commercial SiO2 aerogel (porosity 92%) was treated with 10% H2O2 for 1.5 h and then ball-milled to D50 = 180 nm.

[0040] 2. Sol preparation: Tetraethyl orthosilicate:trimethyl borate = 70:20 (wt%), ethanol solvent, pH = 3.2

[0041] 3. Composite dispersion: Add 30 vol% pretreated aerogel and 3 wt% KH-560, and disperse by ultrasonication at 40 kHz for 75 min.

[0042] 4. Spinning and drying: Centrifugal spinning (4000 rpm), gradient drying: 50℃ / -0.08MPa×3h→90℃×1.5h.

[0043] 5. Stage heat treatment: 80℃ / 2h→350℃ / 1h→650℃ / 2h (N2 protection, heating rate 5℃ / min).

[0044] Example 3

[0045] A borosilicate-nano aerogel composite low dielectric glass fiber

[0046] The specific preparation steps are as follows:

[0047] 1. Aerogel pretreatment: Commercial SiO2 aerogel (porosity 92%) was treated with 10% H2O2 for 1.5 h and then ball-milled to D50 = 180 nm.

[0048] 2. Sol preparation: Tetraethyl orthosilicate:trimethyl borate = 70:20 (wt%), ethanol solvent, pH = 3.2

[0049] 3. Composite dispersion: Add 15 vol% pretreated aerogel and 3 wt% KH-560, and disperse by ultrasonication at 40 kHz for 75 min.

[0050] 4. Spinning and drying: Centrifugal spinning (4000 rpm), gradient drying: 50℃ / -0.08MPa×3h→90℃×1.5h.

[0051] 5. Stage heat treatment: 80℃ / 2h→350℃ / 1h→650℃ / 2h (N2 protection, heating rate 5℃ / min).

[0052] Comparative Example 1

[0053] A low-dielectric glass fiber is prepared using a traditional melt-processing method. The specific steps are as follows:

[0054] 1. Place quartz sand, calcined boric acid, and sodium carbonate in a ball mill jar; use alumina grinding balls with a ball-to-material ratio of 2:1, rotate at 150 rpm, and mix for 4 hours;

[0055] 2. High-temperature melting: Load the mixture into a crucible with a bulk density of 1.2-1.5 g / cm³. 3 ;

[0056] Phased warming:

[0057] Room temperature → 800℃ (5℃ / min), keep warm for 1 hour (sodium carbonate decomposes);

[0058] 800℃→1450℃ (3℃ / min), hold for 2h (initial melting);

[0059] 1450℃→1550℃ (2℃ / min), hold for 4h (complete homogenization);

[0060] 3. Clarification and homogenization: Insert a platinum stirrer and stir at 30 rpm for 30 minutes; introduce argon gas for bubbling (flow rate 0.5 L / min) to remove air bubbles; let stand for 1 hour to homogenize the glass melt (bubble content ≤ 5 / cm). 3 ).

[0061] 4. Wire drawing: A graphite rod is dipped into molten glass and drawn to form initial fibers; Wire drawing speed: 2500 m / min; Cooling method: Forced air cooling (wind speed 10 m / s, temperature 25℃);

[0062] Comparative Example 2

[0063] A borosilicate-nano aerogel composite low-dielectric glass fiber differs from Example 1 in that the aerogel was not activated by H2O2 and ball-milled (original D50 = 1.2 μm), while other parameters are the same as in Example 1.

[0064] The specific preparation steps are as follows:

[0065] 1. Sol preparation: Tetraethyl orthosilicate:trimethyl borate = 70:20 (wt%), ethanol solvent, pH = 3.2

[0066] 2. Composite dispersion: Add 30 vol% pretreated aerogel and 3 wt% KH-560, and disperse by ultrasonication at 40 kHz for 75 min.

[0067] 3. Spinning and drying: Centrifugal spinning (4000 rpm), gradient drying: 50℃ / -0.08MPa×3h→90℃×1.5h.

[0068] 4. Stage heat treatment: 80℃ / 2h → 350℃ / 1h → 650℃ / 2h (N2 protection, heating rate 5℃ / min).

[0069] The performance of the low dielectric glass fibers prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and the results are shown in the table below.

[0070] in,

[0071] Dielectric property testing:

[0072] Agilent 4294A Precision Impedance Analyzer (40Hz-110MHz) (ASTM D150-18)

[0073] Mechanical property testing: Universal testing machine testing (ASTM D638)

[0074] Porosity testing: Micromeritics AutoPore IV 9500 mercury porosimeter (ASTM D4404-18)

[0075]

[0076] As can be seen from the comparison of Examples 1-3, with the increase of the aerogel ratio, the porosity increases, which leads to a decrease in dielectric constant, but the interface defects increase, resulting in a decrease in tensile strength.

[0077] A comparison of Example 1 and Comparative Example 1 reveals that the dielectric constant of Example 1 is reduced by 55.1%, demonstrating that the composite of nano-aerogel and borosilicate glass significantly reduces the dielectric response. Traditional molten fibers have higher strength (3.4 GPa) due to their dense structure, but the mechanical properties of the present invention are significantly better than those of porous materials at the same dielectric level (ε≈3.0).

[0078] A comparison of Example 1 and Comparative Example 2 reveals that the interfacial bonding reinforcement increased the tensile strength by 133%. In Comparative Example 2, the untreated aerogel was unevenly dispersed, resulting in a 18.2% decrease in porosity and an 18.7% increase in dielectric constant.

[0079] As can be seen from the above embodiments and comparative examples, the borosilicate-nano aerogel composite low-dielectric glass fiber provided by this invention has a dielectric constant reduced by more than 55%, and its tensile strength is significantly higher than that of similar porous materials. The gradient drying + dynamic sintering process significantly lowers the industrialization threshold while ensuring performance. Aerogel pretreatment is the key to controlling dispersion uniformity and interfacial bonding. This invention successfully overcomes the long-standing contradiction of "low dielectric - high brittleness" in the field of low-dielectric materials, providing a glass fiber solution with both ultra-low dielectric and high reliability for next-generation high-frequency and high-speed electronic devices, and possesses significant industrial application value.

[0080] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] The above description is merely the preferred embodiment of the present invention. It should be noted that, for those skilled in the art, various modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the principle of the present invention, and these modifications or substitutions can also achieve the technical effects of the present invention, and should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for preparing borosilicate-nano aerogel composite low-dielectric glass fiber, specifically comprising the following steps: (1) Aerogel pretreatment: The nano-aerogel was ultrasonically treated, dried and then ball-milled; (2) Preparation of borosilicate sol: Tetraethyl orthosilicate and trimethyl borate were dissolved in ethanol solution, and the pH was adjusted with hydrochloric acid to form borosilicate sol; (3) Composite dispersion: The pretreated aerogel and silane coupling agent are added to the sol and ultrasonically dispersed; (4) Spinning and forming: Fiber filaments are prepared by centrifugal spinning; (5) Step-by-step heat treatment: The fiber filaments in step (4) are heat-treated in stages to remove solvent, gel-transform and dynamically sinter to obtain composite fibers.

2. The preparation method according to claim 1, characterized in that, The nano-aerogel is a silica aerogel or a silicon carbide aerogel, with an average pore size of 10-50 nm, a porosity ≥80%, and a density ≤0.1 g / cm³. 3 .

3. The preparation method according to claim 1, characterized in that, The ultrasonic treatment in step (1) involves immersion in a 5-15% H2O2 solution for 1-3 hours.

4. The preparation method according to claim 1, characterized in that, In step (2), ethyl silicate and trimethyl borate are mixed at a ratio of 60-75 wt% to 15-25 wt%; the hydrochloric acid is used to adjust the pH range to 2.5-3.5, the reaction temperature is 50-70℃, and the aging time is 12-36 h.

5. The preparation method according to claim 1, characterized in that, The amount of pretreated aerogel added in step (3) is 10-30 vol%, and the amount of silane coupling agent is 1-5 wt%. The silane coupling agent is at least one of γ-aminopropyltriethoxysilane (KH-550) or γ-glycidoxypropyltrimethoxysilane (KH-560).

6. The preparation method according to claim 1, characterized in that, The ultrasonic dispersion step in step (3) is performed with an ultrasonic power of 30-50 kHz and a dispersion time of 60-120 min.

7. The preparation method according to claim 1, characterized in that, The specific steps of the stepped heat treatment in step (5) are as follows: solvent removal stage: vacuum drying at 40-60℃ for 2-4 hours, and atmospheric pressure drying at 80-100℃ for 1-3 hours; gel conversion stage: 300-400℃ for 2-4 hours; sintering stage: heating at 3-8℃ / min to 600-700℃ and holding for 0.5-2 hours, and then cooling at 2-5℃ / min to 500-600℃ and holding for 0.5-1 hours.

8. The borosilicate-nano-aerogel composite low-dielectric glass fiber prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It includes a borosilicate glass matrix and nano-aerogel particles dispersed therein; the borosilicate glass matrix has the following mass percentages: SiO2 55-75%, B2O3 15-25%; and the aerogel volume fraction is 10-30%.

9. The application of the borosilicate-nano aerogel composite low dielectric glass fiber as described in claim 8 in high-frequency communication substrates.

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