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In the present study, fully bio-based photocurable trifunctional benzoxazines derived from resveratrol were designed and characterized for multi-dimensional applications. The molecular structure was confirmed using ATR-FTIR and 1H-NMR spectral techniques. The curing temperature and thermal stability were thoroughly studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) respectively. Notably, in DSC analysis RE-dda exhibited the lowest curing temperature of 191 °C among the synthesised benzoxazines. All the synthesised polybenzoxazines exhibited good thermal stability and start degrading after 263°C. Under UV irradiation, intriguing photoisomerization phenomena was observed in the case of RE-ffa and RE-lee based benzoxazines. The photoluminescence behavior of the UV irradiated benzoxazines was studied using fluorescence spectroscopy and RE-oda displayed a Stokes shift value of 318. Further benzoxazines were reinforced with cashew nut shell cake ash (CNSA) with a view to attain a low value of dielectric constant and to enhance the thermal stability of the composites. An incorporation of 10 wt% CNSA contributes to a reduction in the value of dielectric constant to 1.66, accompanied with a minimal value of dielectric loss of 0.0017. Furthermore, the hydrophobic behavior of the polybenzoxazines, composites and poly(RE-ole) coated cotton fabric was evaluated using water contact angle measurement. Poly(RE-ole) exhibited an impressive water contact angle value of 146°. Moreover, poly(RE-ole) coated cotton fabric displayed enhanced value of water contact angle close to superhydrophobic value of 151°. Data obtained from different studies infer the developed benzoxazines can be considered for water repellent and microelectronics insulation applications. [ABSTRACT FROM AUTHOR]

Silica composites with low dielectric constants have broad application prospects in the fields of low dielectric and thermal insulation materials. However, silica composites still face challenges such as strong water absorption and strict storage conditions in practical applications. Modification of SiO2@quartz fiber composites was conducted with hydrophobic modifiers (hexamethyldisilazane HMDS, stearic acid, sodium dodecyl sulfate) to study the effects of type and mass fraction of hydrophobic modifiers on the hydrophobic and dielectric properties of the composites. The hydrophobic-modified composites were made into coaxial cables to study the effect of heat treatment on the performance of the cables. The results show that the 3% HMDS-modified composite have the best hydrophobic modification with contact angle of 151.6°, the lowest contact angle is 132.6° after 240 days of storage, and the dielectric constant is as low as 1.87 after 200 °C calcination. The hydrophobic-modified composites were made into coaxial communication cables, and the cables had a voltage standing wave ratio of 1.48, an attenuation value of 1.56 dB, and a characteristic impedance of 48 Ω. The hydrophobic-modified composite materials exhibit excellent cable performance, demonstrating potential application value in communication cables and other fields. [ABSTRACT FROM AUTHOR]

High-fidelity communication in extreme environments has attracted significant attention due to its potential applications in aerospace, polar, deep-sea exploration, fire rescue, and nuclear industries. Yet, challenges persist in constructing dielectric layers with both low dielectric constant and high-temperature stability in communication cables. Herein, low-dielectric inorganic composites utilizing pure silicon oxide (SiO 2) are employed as a substitute for conventional organic materials or their composites. By incorporating the in-situ growth of SiO 2 microspheres (m-SiO 2) on the quartz fiber structure, the composites exhibit a reduced dielectric constant while improving mechanical performance. The flexural stress of the m-SiO 2 @quartz fiber composites is twice as high as that of the composites prepared by the ex-situ synthesis method. Furthermore, the m-SiO 2 @quartz fiber composites display high-temperature resistance up to 800 °C with a mass loss less than 1 %. With 30 wt% of quartz fibers, 20 nm of m-SiO 2 , and 6 wt% of the foaming agent, the composites exhibit a dielectric constant of 1.95. Based on the low-dielectric m-SiO 2 @quartz fiber composites, the cable demonstrates a voltage standing wave ratio (VSWR) of 1.46, an attenuation of 1.22 dB, and a characteristic impedance of 48 Ω. [ABSTRACT FROM AUTHOR]

Excellent flame resistance is supposed to be taken into consideration for electronic packaging materials due to the spontaneous combustion of short circuits, except for good mechanical and dielectric properties. Herein, a hyperbranched polyborosiloxane (HPSiB) flame retardant was synthesized via a simple one‐pot transesterification as a multifunctional additive for cyanate ester (CE) resin. The HPSiB with many active terminals features good compatibility with the resin matrix, while catalyzing the curing reaction that conducts at a lower temperature. With as little as 2 wt% HPSiB incorporated, the HPSiB/bisphenol A cyanate ester (BADCy) resin achieves a UL‐94 V0 rating and 32.4% LOI value, and its peak heat release and total smoke production are simultaneously reduced. Its flexural strength and impact strength were significantly enhanced by 30.0% and 85.4%. Besides, the minimum values of dielectric constant and loss can reach 2.77 and 0.0024 at 10 GHz, which are, respectively, reduced by 7.9% and 88.5%. The integration of unique hyperbranched SiOB backbone of HPSiB with CE crosslinked network was responsible for the enhanced overall performance. This work paves a facile strategy to develop multifunctional flame retardant as a promising candidate for the high‐performance electronic packaging materials. Highlights: A novel hyperbranched polyborosiloxane flame retardant was synthesized.HPSiB shows good compatibility and catalyzes the curing reaction of CE resin.HPSiB/CE resin with significantly enhanced flame retardancy was obtained.Simultaneously high toughness and low dielectric loss were achieved.Hyperbranched structure containing SiOB chains led to the great enhancement. [ABSTRACT FROM AUTHOR]

Ceramic-based back covers are commercially utilized as a high-end option for the physical protection of mobile phones. Herein, an unprecedented composite structure consisting of a cordierite (2MgO.2Al 2 O 3 5SiO 2) glass–ceramic strengthened with yttria-stabilized zirconia (YSZ) fillers is introduced as a protective back cover, specifically for next-generation communication mobile phones additionally requiring a low dielectric constant at gigahertz frequencies. Crystallization sequence was rather complicated with the involvements of multiple crystalline phases, α- and μ-cordierite, tetragonal and monoclinic ZrO 2 , and ZrSiO 4 , depending on the glass and composite compositions. This unique approach effectively induced the best mechanical performance for the 10 wt% YSZ/glass–ceramic structure, despite the low sintering temperature of 1050 °C, with the highest Vickers hardness of ∼9.2 GPa and flexural strength of ∼196.8 MPa attained for the optimal composite. Although effective dielectric constant of the composites depended on the relative contents of the evolved crystalline phases, overall dielectric constant was kept low due to the utilization of cordierite glass as the main component. [ABSTRACT FROM AUTHOR]

In order to meet the requirements of highly integrated and miniaturized electronic components, there is an urgent need for low dielectric materials with high mechanical properties and optical transparency in the field of microelectronics. In this study, a series of novel polyimide films (FPI) containing fluorenyl were prepared, and the effects of the fluorenyl content on the thermal, mechanical, and dielectric properties of the copolymerized films were investigated and discussed. The results demonstrate a significant decrease in the dielectric constant of the FPI films following the introduction of fluorenyl into polyimide (PI) chain segment. The FPI films also exhibited high mechanical properties, including tensile strengths between 92 and 106 MPa and elongation at break in the range of 8.4%–13.0%. Additionally, the introduction of the noncoplanar fluorenyl considerably improved the optical transparency and solubility of the FPI film. It is noteworthy that the FPI‐3 has the best dielectric properties, with a low dielectric constant of 2.61 at 10 MHz and shows low water absorption (0.49%). The results show that we have prepared a novel low dielectric PI material film with excellent mechanical properties and optical transparency by introducing fluorenyl into the PI chain segment. These FPI films with satisfactory properties may be good candidates for dielectric materials for electronic components. [ABSTRACT FROM AUTHOR]

This study investigates the effect of 1,2,3,4‐butane tetracarboxylic acid (BTCA) crosslinking treatment on the electrical properties of poly‐p‐phenylene terephthalate (PPTA)/cellulose insulation paper to prepare a novel composite insulation paper with low dielectric constant and good electrical performance. Three‐layer PPTA/cellulose composite paper crosslinked by BTCA under various conditions, composite paper without crosslinking, directly mixed composite paper, and conventional Kraft paper are prepared. The morphology and surface chemical composition of the paper samples are characterized. Dielectric, mechanical, and thermal properties are investigated. Results show that the BTCA concentration of 0.2 mol L−1 with a 180°C curing temperature is the relatively superior crosslinking condition to prepare a novel composite with low dielectric constant and good comprehensive performance. The dielectric constant and loss of the novel composite paper decrease to 3.21 and 0.392 at 50 Hz. The tensile strength of the BTCA crosslinked three‐layer PPTA/cellulose composite paper (thickness: 130 μm) has reached 10.01 kN m−1, increased by 41.6% than the directly mixed composite paper. The novel BTCA crosslinked composite paper also shows improved thermal stability. The BTCA crosslinking proves to be a promising method to improve the dielectric properties and electrical performance of the PPTA/cellulose composite paper. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive overview of the preparation methods for polyhedral oligomeric silsesquioxane (POSS) monomers and polymer/POSS nanocomposites. It focuses on the latest advancements in using POSS to design polymer nanocomposites with reduced dielectric constants. The study emphasizes exploring the potential of POSS, either alone or in combination with other materials, to decrease the dielectric constant and dielectric loss of various polymers, including polyimides, bismaleimide resins, poly(aryl ether)s, polybenzoxazines, benzocyclobutene resins, polyolefins, cyanate ester resins, and epoxy resins. In addition, the research investigates the impact of incorporating POSS on improving the thermal properties, mechanical properties, surface properties, and other aspects of these polymers. The entire study is divided into two parts, discussing systematically the role of POSS in reducing dielectric constants during the preparation of POSS composites using both physical blending and chemical synthesis methods. The goal of this research is to provide valuable strategies for designing a new generation of low dielectric constant materials suitable for large‐scale integrated circuits in the semiconductor materials domain. [ABSTRACT FROM AUTHOR]

The bifunctional phenol (BBC) was derived from a sustainable resource, viz., cardanol, which is utilized to prepare benzoxazines using five structurally different amines with paraformaldehyde through Mannich condensation. The molecular structure of the synthesized benzoxazines were confirmed by FTIR and 1H-NMR spectral analyses. The curing behavior of the benzoxazines was studied using DSC and among all the synthesized benzoxazines, BBC-imp exhibits lower curing temperature of 224 °C than that of others. The thermal stability of all the polybenzoxazines were analyzed using TGA and poly(BBC-a) was found to be better thermally stable than that of other polybenzoxazines. Poly(BBC-tfma) showed the highest value of water contact angle of 152° and the lowest value of dielectric constant of 4.50. All the synthesized BBC-based polybenzoxazines possess good anti-corrosion property with a protection efficiency of 99%. Data obtained from different studies suggest that the polybenzoxazines developed in the present work can be considered for possible use in the form of sealants, encapsulants, adhesives and coatings for microelectronics and other industrial applications for better performance. [ABSTRACT FROM AUTHOR]

Although polyimide films have a low dielectric constant, with the advent of the 5G era, the dielectric properties of the material are required to be further improved. Therein, we prepared controlled hollow mesoporous SiO2 nanomicrospheres by the hard template method to make mesoporous low dielectric polyimide films. The composite membrane exhibits better thermal stability, mechanical properties, and hydrophobicity compared to the pure membrane. Hollow mesoporous SiO2 dispersed in polyimide can reduce the inhomogeneity of charge distribution between molecules and reduce the interaction between polar chemical bonds and aromatic rings, thus improving the dielectric properties of the whole film. The minimum dielectric constant of the composite films was 2.80 when the hollow mesoporous SiO2 was added at 1.0%. These results fully indicate that the addition of hollow mesoporous SiO2 is beneficial to the multifaceted performance of the polyimide films. Highlights: Preparation of hollow mesoporous SiO2 microspheres by using different polystyrene microsphere solutions and TEOS ratios.Synthesis of composite films with different contents of hollow mesoporous SiO2 as functional fillers.The effect of hollow mesoporous SiO2 content on the mechanical properties and thermal stability of PI composite films was investigated.Addition of hollow mesoporous SiO2 reduces the dielectric constant of polyimide composite films. [ABSTRACT FROM AUTHOR]

Dielectric materials with superb thermal and electrical properties are highly desired for high-voltage electrical equipment and advanced electronics. Here, we propose a novel strategy to improve the performance of epoxy composites by employing boron nitride nanosheets (BNNSs) and γ-glycidyl ether oxypropyl sesimoxane (G-POSS) as functional fillers. The resultant ternary epoxy composites exhibit high electrical resistivity (1.63 × 1013 Ω·cm) and low dielectric loss (<0.01) due to the ultra-low dielectric constants of cage-structure of G-POSS. In addition, a high thermal conductivity of 0.3969 W·m−1·K−1 is achieved for the epoxy composites, which is 114.66% higher than that of pure epoxy resin. This can be attributed to the high aspect ratio and excellent thermally conductive characteristics of BNNSs, promoting phonon propagation in the composites. Moreover, the epoxy composite simultaneously possesses remarkable dynamic mechanical properties and thermal stability. It is believed that this work provides a universal strategy for designing and fabricating multifunctional composites using a combination of different functional fillers. [ABSTRACT FROM AUTHOR]

Abstract Epoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards.

The rapid development of integrated circuits puts forward higher requirements for low dielectric constant polymers. In this study, two fluorinated benzoxazine monomers, bis‐(3,4‐dihydro‐3‐(4‐fluoro‐3‐(trifluoromethyl)phenyl)‐2H‐1,3‐benzoxazine)isopropane (BA‐ftfa) and bis‐(3,4‐dihydro‐3‐(4‐fluoro‐3‐(trifluoromethyl)phenyl)‐2H‐1,3‐benzoxazine)isoperfluoropropane (BAF‐ftfa), were successfully synthesized. Differential scanning calorimeter (DSC) was used to monitor the thermal curing behaviors of the monomers and their mixtures. Five groups of polybenzoxazine samples with different fluorine content (25% ~ 35%) were obtained by copolymerizing the two monomers with different mass ratios. The effects of fluorine content on dielectric properties were investigated and the results show that PBAF‐ftfa with the highest fluorine content has the lowest dielectric constant of 2.53 at 1 MHz. Furthermore, the results of thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) show that all polymers possess excellent thermal stability and exhibit high glass transition temperatures over than 180°C. [ABSTRACT FROM AUTHOR]

The synthesis of a low dielectric constant polyimide (PI) with a polyhedral oligomeric silsesquioxane (POSS) cross-linked structure is presented. A non-planar conjugated diamine monomer (FSNH2) with two -CH=CH2 reactive groups was first synthesised in a two-step process, and then two polyimides were synthesized by PSS-Octavinyl (OVPOSS) substituted, FSNH2 and dianhydride. OVPOSS cross-linked polyimides have good thermal stability and low dielectric constant. 6FDA-FSNH2-OVPOSS(6FPI-3) can reach a minimum dielectric constant of 2.08 (108 Hz) and a dielectric loss of 0.008 (108 Hz). In addition, the cross-linked structure of the OVPOSS and polyimide chains prevents the agglomeration of OVPOSS to a certain extent and improves the tensile strength and elongation at break of the polyimides, which has great application potential in large-scale integrated circuits. [ABSTRACT FROM AUTHOR]

Epoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards. [ABSTRACT FROM AUTHOR]

Cobalt (Co) is proposed to replace copper (Cu) as a conductor in the back-end-of-line (BEOL) interconnects of integrated circuits. In this study, the electric characteristics and reliability of the integration of Co with various dielectric films (SiO2, dense, and porous low-k SiOCH films) under thermal and electrical stress were compared. Thermal annealing repaired sputtering-Co-deposition-induced damage to the dielectric film but reduced the breakdown field and time-dependence-dielectric-breakdown (TDDB) times due to the diffusion of Co atoms. After annealing, the SiO2 film had the largest reductions in the breakdown field, TDDB failure time, and electric field acceleration factor, indicating that the diffusion of Co atoms dominates in the oxygen-rich surface. Under electrical stress, the drift of Co atoms favors the porous low-k film with the assistance of porosity. As a result, a barrier is required for Co metallization. To achieve barrier-free or barrier-less processing in Co metallization, the dense low-k film is the best option to integrate with Co. [ABSTRACT FROM AUTHOR]

The objective of this study is to prepare a new poly(aryl ether ketone) (PAEK) with low dielectric constant, high transparency and heat resistance by introducing fluorine atoms and phenolphthalein (PHPH) groups into the polymer backbone. The chemical structure of PAEK random copolymers was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR) and X-ray diffraction (XRD),, and the molecular weight of PAEK was determined by gel permeation chromatography (GPC). It is found that these random copolymers are soluble in common organic solvents, especially low boiling point solvents, such as CHCl3, tetrahydrofuran (THF) and dimethylacetamide (DMAc). Transparent, uniform and flexible films were prepared by casting from DMAc solvent. The PAEK copolymers exhibit high glass transition temperature (163–220 °C by differential scanning calorimetry (DSC) and 168–227 °C by dynamic mechanical analysis (DMA)) and thermal stability with 5% weight loss temperatures of 461–525 °C. The PAEK films show good mechanical properties with tensile strengths of 50–62 MPa. The dielectric constant (k) is only 2.31–3.08, and the loss tangent is only 0.003–0.009 at 1 MHz. All films exhibit excellent optical transparency, their UV cutoff wavelength is shorter than 386 nm, and the transmittance at 450 nm is higher than 80%.

Dielectric composites with low dielectric constants (ε), low dielectric loss (tan δ), and excellent thermal-mechanical stability are highly desired for high signal transmission speed and high device integration. Polytetrafluoroethylene (PTFE) based composites exhibit tremendous potential due to the outstanding dielectric properties and high-frequency stability of PTFE. However, achieving PTFE-based dielectric composites with thermal-mechanical stability and low dielectric constant is challenging. Herein, we develop a glass fiber/polytetrafluoroethylene (GF/PTFE) composite for high-frequency communication applications with a designed skeleton structure. By the paper-making process, the glass fiber can be dispersed in random directions to set up a skeleton with the PTFE matrix entering the space in the fiber network. The modification of GF was also carried out to low down the dielectric loss of the composite. Benefiting from the supporting effect of the skeleton structure and surface modification, the thermal-mechanical stable dielectric composite was achieved with a low dielectric constant, and dielectric loss remained (m-GF content = 15 wt%, ε = 2.326 and tan δ = 5.24 × 10−3 at 30 GHz, xy-CTE = 29 ppm/°C and z-CTE = 47 ppm/°C). Moreover, the composites also have good dielectric constant frequency stability and thermal conductivity. Thus, this work provided an effective way to tailor the structure of functional composites with disordered fiber fillers. [ABSTRACT FROM AUTHOR]

There is an increasing demand for polyimide (PI) with excellent mechanical properties, good heat resistance, and low dielectric constant in integrated circuits and advanced packaging. Based on this, we report a strategy of tailoring the PI via fluorinated nanofillers modification to improve its mechanical properties, heat resistance, hydrophobicity, and reduce its dielectric constant. Specifically, different fluorinated nanofiller, including fluorinated graphene (FG), fluorinated carbon nanotubes (FCNT), fluorinated carbon black (FCB), and fluorinated graphene quantum dots (FGQD) were introduced into PI matrix to prepared composite films by a simple method of in‐situ polymerization, and the effect of different nanofillers on the properties of polyimide was systematically investigated. The results showed that the introduction of fluorinated nanofillers significantly improved the comprehensive performance of the composite films, especially the FGQD. FGQD/PI composite film with 0.5 wt% FGQD exhibits superior tensile strength (145.8 MPa), Young's modulus (2.83 GPa) and elongation at break (45.4%) the best comprehensive performance which are 10.0%, 19.4%, and 32.0% of those of pure PI, respectively. Most importantly, the FGQD/PI composite film shows decreased dielectric constant (from 3.38 to 2.93) at 1 MHz improved hydrophobicity and excellent heat resistance. The FGQD/PI composite film exhibits excellent comprehensive performance, thereby showing the potential in the future development of advanced packaging and microelectronics industry. [ABSTRACT FROM AUTHOR]

Composite silica-based glasses were synthesized with varying concentrations of Er3+ by sol-gel route. The presence of alkali sodium ions reoriented the silica tetrahedra, eventually forming the cristobalite phase in the glasses. The addition of Er3+ reduces the crystallite size from 23.8 nm to 6.9 nm, while retaining the fractional ceramic attribute for effectuating mechanical stability and ductility. Band gap energy increases with Er3+ doping by the principles of the Burstein-Moss shift, increasing transmittance to 90% in the glasses. The density of the glasses increases with erbium content, with a subsequent increase in ionic bonding as validated by the metallization criterion. Judd OFelt (JO) parameters were evaluated from the oscillator strengths of absorption transitions, identifying decreasing covalency in the glass systems. Broad bandwidth and lifetime of 79.9 nm and 6.2 ms respectively were obtained for near-infrared (NIR) transmission at 1.47 μm, suitable for an S-band telecommunication window. The material has potential red lasing performance corresponding to the transition: 4 F 9 / 2 → 4 I 15 / 2 . Low dielectric constants and decreasing activation energy of the glass material at higher frequencies, as derived from Arrhenius plots, is suggestive of a cost-effective inter-layer dielectric substrate for microwave signal propagation. This could be favorably capitalized for micro-fabrication in integrated electronic industries, employing the Low-Temperature Co-fired Ceramic (LTCC) technology as a strategic alternative to the ceramic substrates devised otherwise using high sintering temperatures. [ABSTRACT FROM AUTHOR]

Because of the increase in the transmission voltage levels, the demand for insulation reliability of power transformers has increasingly become critical. Cellulose insulating paper is the main insulating component of power transformers. To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size, reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired. Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties, renewability, biodegradability and abundance. The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification. This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers. All the mentioned methods are analyzed in this study. Finally, some recommendations for future modified cellulose insulating paper research and applications are proposed. This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future. [ABSTRACT FROM AUTHOR]

To develop plasma-resistant glass materials suitable for semiconductor etching processes, we introduced alkaline earth oxides (ROs) into a Li2O–Al2O3–SiO2 (LAS) glass. Analysis of glass properties with respect to the additives revealed that among the analyzed materials, the LAS material in which Li2O was partially replaced by MgO (MLAS) exhibited the most favorable characteristics, including a low dielectric constant (6.3) and thermal expansion coefficient (2.302 × 10−6/°C). The high performance of MLAS is attributed to the high ionic field strength of Mg2+ ions, which restricts the movement of Li+ ions under the influence of electric fields and thermal vibrations at elevated temperatures. When exposed to CF4/O2/Ar plasma, the etching speed of RO-doped glasses decreased compared with that of quartz and LAS glass, primarily owing to the generation of a high-sublimation-point fluoride layer on the surface. Herein, MLAS demonstrated the slowest etching speed, indicating exceptional plasma resistance. X-ray photoelectron spectroscopy analysis conducted immediately after plasma etching revealed that the oxidation-to-fluorination ratio of Li was the lowest for MLAS. This observation suggests that the presence of Mg2+ ions in the plasma discharge inhibits the migration of Li+ ions toward the surface, thereby contributing to the excellent plasma resistance of MLAS. [ABSTRACT FROM AUTHOR]

The (Al 1- x B x) 2 Mo 3 O 12 ceramics with double phases were prepared by solid-phase sintering method at the temperature from 725 to 800 °C for LTCC application. Through XRD pattern and Rietveld refinement analysis, it was confirmed that the (Al 1- x B x) 2 Mo 3 O 12 composition consists of the coexistence of double phase (the monoclinic structure of the P 2 1 / a space group and the orthorhombic structure of the Pnca space group), and the orthorhombic phase was increased with boron substitution. The microwave dielectric properties of the (Al 1- x B x) 2 Mo 3 O 12 ceramic series were impacted by double-phase formation (crystal structure ratio), which increases the densification and grain uniformity. With the boron substitution, the (Al 1- x B x) 2 Mo 3 O 12 ceramic series demonstrate outstanding microwave dielectric properties (ε r = 4.04, Q × f = 35870 GHz @ 15 GHz, τ ƒ = 4.2 ppm/°C) with high relative density (ρ rel ≈ 98.84%) and thermal conductivity κ = 0.88 W/m.K for x = 0.3 at 775 °C, indicate that it is a promising candidate for LTCC substrate material. [ABSTRACT FROM AUTHOR]

A series of epoxy resins containing various trifluoromethyl groups were synthesized and thermally cured with diaminodiphenylmethane (DDM) and aminophenyl sulfone (DDS). All epoxy resins exhibited excellent thermal stability with the glass transition temperatures of above 128 °C and 5% weight loss temperatures of above 300 °C. DDS-cured epoxy resins possessed higher thermal stability than that of DDM-cured epoxy resins, while DDM-cured epoxy resins showed better mechanical, dielectric, and hydrophobic properties. Additionally, DDM-cured epoxy resins with different locations and numbers of trifluoromethyl groups showed flexural strength in the range of 95.55~152.36 MPa, flexural modulus in the range of 1.71~2.65 GPa, dielectric constant in the range of 2.55~3.05, and water absorption in the range of 0.49~0.95%. These results indicate that the incorporation of trifluoromethyl pendant groups into epoxy resins can be a valid strategy to improve the dielectric and hydrophobic performance. [ABSTRACT FROM AUTHOR]

With the advent of the 5 G era, advanced packaging applications such as wafer-level fan-out packaging have emerged thanks to efforts to reduce signal loss and increase signal transmission rates. As one of the key materials employed in telecommunication devices, the interlayer dielectric material directly affects signal transmission and device reliability. Among them, polyimide (PI) has become an important interlayer dielectric material because of its excellent comprehensive properties. However, in order to meet the needs high-frequency and high-speed circuits for 5 G networks, it will be necessary to further reduce the dielectric constant and dielectric loss of PI. PI is widely used as a flexible dielectric material due to its excellent electrical insulation properties (dielectric constant ≈ 3.0–4.0, dielectric loss ≈ 0.02), mechanical properties, and thermal resistance. However, further reduction in the dielectric constant will be needed in order for PI-based materials to better meet the current high integration development needs of the microelectronics industry. This article starts from strategies to prepare low dielectric PI that have been developed in the last decade, based on a more systematic and inductive analysis, and prospects the development potential of low dielectric PI.

Dielectric materials with superb thermal and electrical properties are highly desired for high-voltage electrical equipment and advanced electronics. Here, we propose a novel strategy to improve the performance of epoxy composites by employing boron nitride nanosheets (BNNSs) and γ-glycidyl ether oxypropyl sesimoxane (G-POSS) as functional fillers. The resultant ternary epoxy composites exhibit high electrical resistivity (1.63 × 1013 Ω·cm) and low dielectric loss (−1·K−1 is achieved for the epoxy composites, which is 114.66% higher than that of pure epoxy resin. This can be attributed to the high aspect ratio and excellent thermally conductive characteristics of BNNSs, promoting phonon propagation in the composites. Moreover, the epoxy composite simultaneously possesses remarkable dynamic mechanical properties and thermal stability. It is believed that this work provides a universal strategy for designing and fabricating multifunctional composites using a combination of different functional fillers.

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In the rapidly growing area of high-frequency communications, polyimide films with ultralow dielectric constant and dielectric loss, adequate insulating strength, and recyclability are in high demand. Using a synthesized soluble fluorinated polyimide, a series of recyclable porous dielectric films with varying porosities were fabricated in this study through nonsolvent-induced phase separation. By manipulating the mass ratio of the binary solvent used to dissolve the polyimide, the shape, size, and size distribution of the pores generated throughout the polyimide matrix can be accurately regulated. The porosity and average pore size of the as-prepared porous films were adjustable between 71% and 33% and between 9.31 and 1.00 μm, respectively, which resulted in a variable dielectric constant of 1.51–2.42 (100 kHz) and electrical breakdown strength of 30.3–119.7 kV/mm. The porous sPI film with a porosity rate of 48% displayed a low dielectric constant of 2.48 at 10 GHz. Coupled with their superior thermal stability, mechanical characteristics, and recyclability, these porous polyimide films are highly promising for constructing high-frequency microelectronic devices. [ABSTRACT FROM AUTHOR]

Fluoropolymers find applications in heat‐resistant cables, chemical‐resistant linings, electronic components, cladding materials, and weather‐resistant films. Therefore, it is imperative to improve their temperature resistance level and dielectric properties. In this study, a series of new fluorinated epoxy‐phthalonitrile resins with different mass ratios were prepared by adding phthalonitrile to the epoxy resin matrix, followed by a two‐step reaction of the amine with the epoxy resin at low temperature, and then by the reaction of the nitrile with the epoxy resin and the nitrile group at high temperature. The thermal stability and thermal oxidation stability of the cured products were improved; the initial decomposition temperature for 5% weight loss in air was 375.3°C, indicating good heat resistance performance. In addition, the glass transition temperature and storage modulus of the fluorinated epoxy‐phthalonitrile resins cured products increased with an increase in phthalonitrile content. The storage modulus remained above 1500 MPa until 150°C. The glass transition temperature of fluorinated epoxy‐phthalonitrile resins (at a mass ratio of 5:5) was 180°C, much higher than that of the epoxy resin (which was 140°C). Moreover, the dielectric constant of fluorinated phthalonitrile‐epoxy resin (5:5 mass ratio) was 2.01, which was 39.63% lower than that of fluorinated epoxy resin. The thermoset matrix has potential applications in the fabrication of a variety of low dielectric constant composites for electronic device related industries. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modified polyimides (MPIs) show great potential towards 5G communication applications, due to its excellent thermal stability, mechanical property and chemical stability as compared to most of polymers. Introducing fluoride groups or porous structure is favorable to ultra-low dielectric constant (Dk) and dielectric loss (Df). However, the cost of the fluorinated MPIs is high and their synthetic processes are complicated, and porous MPIs suffer poor mechanical properties. Also, increasing the fraction of free volume is a very effective way to lower Dk through introducing more ultra-low-Dk air component. However, most of this kind of MPIs lag far behind the fluorinated MPIs and the porous MPIs in terms of ultra-low Df, hindering the application of MPIs in high-speed communication devices. Thus, it is highly desirable to develop intrinsic ultra-low-Dk/Df MPIs at high frequency with less fluoric groups and nonporous structure. Herein, we introduce a facile and effective strategy to lower Dk and Df through introducing rigid and large sterically hindered aromatic groups into MPIs. On the one hand, their large steric hindrance effect leads to low Dk by increasing intrinsic free volume. On the other hand, the resulting highly stiff polymer chain and strong intermolecular interaction are favorable to reduce Df by inhibiting dipole orientations. Based on this strategy, the spirobifluorene groups are preferred. The as-prepared MPIs show excellent dielectric performance with low Dk of 2.74–2.76 and low Df of 0.00599 at 10 GHz, to some extent, exceeding the multiple fluorinated MPI with Dk/Df of 2.67/0.00663 at 10 GHz. [ABSTRACT FROM AUTHOR]

One challenge in the high‐performance dielectric material of polyimide (PI) is to obtain the excellent comprehensive properties at low curing temperature for advanced IC package. In this work, 6‐aminoquinoline (AQL) is introduced through covalent bonds for end capping to obtain a low‐temperature curable PI at first. The results demonstrate that with very limited introduce (2.76%) of AQL, the imidization index could reach as high as 1.01 at 200°C. Then, fluorinated nano carbon (FC) is further introduced resulting in the fluorinated nano carbon/polyimide (FCPI) composites, which effectively reduces the dielectric constant (1 wt%, 2.75 @ 1 MHz). Besides, the as‐prepared FCPIs also possess excellent thermal property of which FCPI‐0.3 exhibited the 5% weight loss temperature of 540°C and the glass transition temperature is also as high as 385°C. Furthermore, the tensile strength of the film is 127 MPa, the elongation at break is around 15.82%, and the Youngs' modulus is about 3.10 GPa proving the superior mechanical property. As a result, the successful preparation of the FCPI nanocomposites not only possess low‐temperature curing and low‐dielectric performance but also exhibit excellent thermal and mechanical properties, which shows a wide range of application prospects in the field of microelectronics for the advanced electronic package. [ABSTRACT FROM AUTHOR]

MSO4 (M = Ca, Sr, Ba) ceramics with relative densities exceeding 96% were prepared by solid‐state sintering at low sintering temperatures of 625–875°C, and their structures and microwave dielectric properties at 10–19 GHz were characterized. MSO4 ceramics crystallized in orthorhombic symmetry with the space groups of Amma for CaSO4 and Pnma for SrSO4 and BaSO4. The optimal microwave dielectric properties were obtained with εr = 5.85, Qf = 57 000 GHz, τf,W = −98.8 ppm/°C for CaSO4, εr = 10.95, Qf = 15 500 GHz, τf,W = 101.6 ppm/°C for SrSO4, and εr = 9.42, Qf = 38 200 GHz, τf,W = −4.7 ppm/°C for BaSO4. The increased εr and τf,W while decreased Qf value in the order of CaSO4, BaSO4, and SrSO4 were attributed to the enhanced rattling effect of M2+. Besides, the temperature dependence of τf was weak for CaSO4 and BaSO4, whereas much stronger for SrSO4. As most low‐εr microwave dielectric ceramics are of large negative τf, the near‐zero τf of BaSO4 and positive τf of SrSO4 are rare, indicating they are potential candidates for millimeter‐wave communication as a temperature‐stable dielectric ceramic and a compensator for tuning negative τf to near‐zero, respectively. [ABSTRACT FROM AUTHOR]

In this paper, SrY0.15Ce0.85O2.925 ceramic materials were prepared by a solid-phase reaction method, and their phase composition, structure, sintering characteristics and microwave dielectric properties were investigated by XRD, SEM and microwave vector network analyzer. As the sintering temperature was 1 450 ℃, the SrY0.15Ce0.85O2.925 ceramics exhibited the optimized comprehensive performances with bulk density of 5.2 g/cm³, relative density of 92.7%, Q×f =21 503 GHz, εr=23.83 and τf=-46.43 ppm/℃, indicating that the SrY0.15Ce0.85O2.925 ceramics are the alternative material for the preparation of modern mobile communication devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Low-dielectric materials have found broad applications in microelectronics but are limited by poor mechanical properties and thermal conductivity. In this study, a class of nanocomposite films based on fluorinated graphene (FG) was developed by replacing the traditional polymer matrix with a 3D interconnected poly-(p-phenylene benzobisoxazole) (PBO) nanofiber network. The FG nanosheets are uniformly distributed in the porous network of PBO nanofibers (PBONF) and stacked orderly to form a nacre-like layered structure while paving effective thermal conduction paths. Ultimately, the strong interfacial bonding and efficient synergy between FG and PBONF endow the composite films with unparalleled tensile properties (strength and modulus up to 295.4 MPa and 7.79 GPa, respectively) and folding endurance (no drop in tensile properties after 1000 folds), ultralow dielectric constant (as low as 1.71), and excellent thermal conductivity (12.13 W m–1 K–1). In addition, these FG/PBONF composite films also exhibit an ultrahigh thermal stability (5% weight loss temperature higher than 540 °C), which makes them promising for the heat dissipation of high-power electronic devices in extreme environments. [ABSTRACT FROM AUTHOR]

High-performance composites with a resin matrix are urgently required for electronic packaging due to their low dielectric constant, outstanding high temperature resistance, excellent corrosion resistance, light weight and easy molding. In this work, hollow-glass-microsphere (HGM)-filled fluorinated-phthalonitrile (PBDP) composites, with filler contents ranging from 0 to 35.0 vol.%, were prepared in order to modify the dielectric properties of the phthalonitrile. Scanning electron microscopy (SEM) observations indicate that the modified HGM particles were uniformly dispersed in the matrix. The PBDP/27.5HGM-NH2 composite demonstrates a low dielectric constant of 1.85 at 12 GHz. The 5% thermogravimetric temperature (T5) of composites with silanized HGM filler (481–486 °C) is higher than the minimum packaging-material requirements (450 °C). In addition, the heat-resistance index (THRI) of PBDP/HGM-NH2 composites reached as high as 268 °C. the storage modulus of PBDP/HGM-NH2 composites were significantly increased to 1283 MPa at 400 °C, an increase by 50%, in comparison to that of PBDP phthalonitrile resin (857 MPa). The excellent dielectric and thermal properties of the present composites may pave a way for comprehensive applications in electronic packaging and thermal management for energy systems. [ABSTRACT FROM AUTHOR]

In this study, a novel diamine monomer containing ester and phenyl moieties, 1,2-diphenylethane-1,2-diyl bis(4-aminobenzoate) (1,2-DPEDBA), was synthesized through a three-step reaction. Using this diamine, a novel polyimide (PI) film was prepared with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) as a counter dianhydride through a typical two-step chemical imidization. For comparison, poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA-ODA PI) was also synthesized via thermal imidization. The resulting 6-FDA-DPEDBA PI film was not only soluble in common polar solvents with high boiling points, such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF), but also soluble in common low-boiling-point polar solvents, such as chloroform (CHCl3) and dichloromethane (CH2Cl2), at room temperature. The resulting novel PI showed a 5% weight loss temperature (T5d) at 360 °C under a nitrogen atmosphere. The resulting PI film was colorless and transparent with a transmittance of 87.1% in the visible light region ranging from 400 to 760 nm. The water absorption of the novel PI film was of 1.78%. The PI film also possessed a good moisture barrier and hydrophobicity. Furthermore, the resulting PI film displayed a low dielectric constant of 2.17 at 106 Hz at room temperature. In conclusion, the novel PI film exhibited much better optical transparency, lower moisture absorption, and a lower dielectric constant as well as better solubility than the PMDA-ODA PI film, which is insoluble in any solvent, although its thermal stability is not better than that of PMDA-ODA PI. [ABSTRACT FROM AUTHOR]

Novel fluorine-containing polyimides were synthesized through copolymerization by using 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) and 4,4′-(4,4′-isopropydenediphenox-y) bis-(phthalic anhydride) (BPADA) as dianhydrides and 4,4′-oxydianiline (ODA) and 2,2 - Bis [4-(4-aminophenoxy)phenyl]-hexafluoropropanane (HFBAPP) as diamines. Noncoplanar structure, flexible ether bond, and trifluoromethyl give the polyimide good thermoplastic, solubility, and heat resistance. The glass transition temperatures of polyimide films are 232.5°C∼262.2°C, the 5% weight loss temperatures are 521.5°C∼531.0°C, and the residual mass is more than 50% as heating to 800°C. With the increase of HFBAPP content in diamine, the dielectric constant of the material decreases from 3.21 to 2.78, and the dielectric loss decreases from 0.00962 to 0.00687 at 1 MHz, which greatly improves the dielectric properties of the material. [ABSTRACT FROM AUTHOR]

Polycarbonate/Polypropylene (PC/PP) alloy is a typical thermodynamically incompatible system. In this work, ethylene‐methyl acrylate copolymer (EMA), methoxamine hydrochloride‐grafted POE (POE‐g‐MAH), ethylene‐butyl acrylate‐glycidyl methacrylate copolymer (EAY), a self‐made compatibilizer (PPM‐g‐GMA) of a mixture of glycidyl methacrylate grafted PP (PP‐g‐GMA) and glycidyl methacrylate‐grafted POE (POE‐g‐GMA) were selected as compatibilizer to prepare PC/PP alloys with the mass ratio of 65:30. Systematical studies of compatibilizer type, content and its effects on microstructure, mechanical properties, dielectric properties, dielectric properties and dynamic rheological properties have been carried out in this PC/PP alloys. The results demonstrated that all the compatibilizers in this article resulted in an effective improvement of the compatibility of PC/PP alloys, and the self‐made compatibilizer of PPM‐g‐GMA exhibited a significant improvement over the other three compatibilizers in notched izod impact strength, tensile strength, and bending strength. In addition, a relative low dielectric constants and dielectric losses under 2.5 GHz electric field could be obtained with the assistance of POE‐g‐MAH and PPM‐g‐GMA, indicating its possible application in dielectric materials. [ABSTRACT FROM AUTHOR]

The synthesis of transparent fluorinated polystyrene siloxanes with good thermostability and dielectric properties. [Display omitted] • Three silicone monomers were prepared by Piers-Rubinsztajn reaction. • The obtained polystyrene siloxanes exhibit good and stable dielectric properties. • All polystyrene siloxanes show high thermostability and good transparency. Three silicone monomers were prepared by Piers-Rubinsztajn reaction which catalyzed condensation reaction of hydrosilane and alkoxysilane under mild conditions. Due to the thermo-crosslink reaction of styrene groups with vinyl of siloxane, the obtained polystyrene siloxanes (P1 - P3) showed high thermostability with the 5 % weight loss temperature (T 5d) of above 440 °C and the residue at 1000 °C of over 40 %. Thanks to the introduce of trifluoromethyl with large free volume, P3 exhibited low dielectric constant (D k) of 2.45 and ultralow dielectric loss (D f) of 3.41 × 10−3 at high frequency of 10 GHz. Meanwhile, P1 - P3 remained stable dielectric properties after being soaked in boiling water for 72 h. In particularly, all polymers exhibited good transparency with transmittance of 90% varying from 500 nm to 1000 nm. These materials can meet the requirements of matrix materials or packaging resins used in high-frequency communication equipment. [ABSTRACT FROM AUTHOR]

[Display omitted] • The three novel quinoxaline-based PAEs have been successfully prepared. • PAE films exhibit ultra-low D k (2.45–2.87) and D f (0.0019–0.0057) at high frequency. • PAEs show excellent hydrophobic, solubility and thermal properties. With the rapid growth of 5G communication technology, low-dielectric materials can decrease the loss of the signal during transmission. Hence, there is an urgent need to develop high-performance materials with low dielectric constant (D k) and dielectric loss (D f) at high frequency. In this study, we propose a strategy that combines bulk rigid quinoxaline structure and low polarizability trifluoromethyl group to prepare poly (aryl ether)s (PAEs) with low D k and D f at high frequencies. The effect of methyl substituents on the properties of PAEs was focuses on investigated. Accordingly, three difluoro-monomers containing quinoxaline structures were designed and prepared and novel quinoxaline-based PAEs with different numbers of methyl substituents were synthesized by nucleophilic condensation reactions with the bisphenol monomer hexafluorobisphenol A (BP6F). Test results that the resultant PAEs exhibited excellent thermal and solubility properties, with 5 % thermal decomposition temperatures (T d5%) in the range of 500−515 °C and glass transition temperatures (T g) reaching 225 °C. Furthermore, these PAE films show outstanding optical transparency, with cut-off wavelengths of 398−400 nm and above 87 % transmission at 800 nm. Most importantly, the novel PAE films possess ultra-low D k and D f , with the lowest values reaching 2.45 and 0.0024 at 10 GHz and maintain low water absorption (0.53–0.63 %). The excellent properties of novel quinoxaline-based PAEs provide its application potential in the field of high-frequency communications. [ABSTRACT FROM AUTHOR]

To develop plasma-resistant glass materials suitable for semiconductor etching processes, we introduced alkaline earth oxides (ROs) into a Li2O–Al2O3–SiO2 (LAS) glass. Analysis of glass properties with respect to the additives revealed that among the analyzed materials, the LAS material in which Li2O was partially replaced by MgO (MLAS) exhibited the most favorable characteristics, including a low dielectric constant (6.3) and thermal expansion coefficient (2.302 × 10−6/°C). The high performance of MLAS is attributed to the high ionic field strength of Mg2+ ions, which restricts the movement of Li+ ions under the influence of electric fields and thermal vibrations at elevated temperatures. When exposed to CF4/O2/Ar plasma, the etching speed of RO-doped glasses decreased compared with that of quartz and LAS glass, primarily owing to the generation of a high-sublimation-point fluoride layer on the surface. Herein, MLAS demonstrated the slowest etching speed, indicating exceptional plasma resistance. X-ray photoelectron spectroscopy analysis conducted immediately after plasma etching revealed that the oxidation-to-fluorination ratio of Li was the lowest for MLAS. This observation suggests that the presence of Mg2+ ions in the plasma discharge inhibits the migration of Li+ ions toward the surface, thereby contributing to the excellent plasma resistance of MLAS.

Colorless and transparent polymer films and sheets with good high-temperature resistance and low dielectric constant (low-Dk) and low dissipation factors (low-Df) features are highly desired in advanced optoelectronic integrated circuits (OEIC) fabrications. In the current work, a series of semi-alicyclic polyimide (PI) powders were first prepared by the onestep high-temperature polycondensation of an alicyclic dianhydride, hydrogenated 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (HBPDA) and aromatic diamines which were beneficial for endowing the derived PI films with low-Dk features, including 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) for PI-1, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BDAF) for PI-2, and 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene (BAOFL) for PI-3. Then, the derived PI powders were fabricated into colorless films and light-colored sheets, respectively. The freestanding flexible and tough PI films showed excellent optical transparency with the ultraviolet (UV) cutoff wavelength (λcut) lower than 300 nm, the optical transmittance higher than 85% at the wavelength of 400 nm, yellow indices (b*) lower than 1.0, and haze values lower than 1.2%. The hot-processed PI sheets also exhibited light colors. The PI films and sheets showed good thermal stability with the glass transition temperatures (Tg) higher than 220 °C. More importantly, the derived semi-alicyclic PI sheets showed Dk and Df values as low as 2.56 and 0.008 at 1 MHz, respectively.

The advent of high frequency communication era presents new challenges for further development of dielectric polymer materials. In the field of communication, efficient signal transmission is critical. The lower the dielectric constant of the dielectric material used, the lower the signal delay and the higher the signal fidelity. The preparation of polymer materials with low dielectric constant or reduce the dielectric constant of polymer materials becomes a key research topic. Summarizing past progress and providing perspective, this paper primarily discusses the intrinsic low dielectric polymers, fluorine doped low dielectric polymers, and microporous low dielectric polymers, while predicting the research trend of low dielectric materials. [ABSTRACT FROM AUTHOR]

The (F-SBA-15) dispersed aliphatic chain containing polybenzoxazine nanocomposite coating materials having better corrosion resistance property has been developed. The new aliphatic chain containing polybenzoxazines is synthesized from n-octylamine, bisphenol-A and paraformaldehyde involving mannich condensation reaction. The structure of polymer and monomer was examined with the help of proton magnetic resonance1NMR spectroscopy and Fourier transform IR spectroscopy. The polybenzoxazine composites were prepared n-octylamine, bisphenol-A and paraformaldehyde and using varying percentages (1, 5, 10 wt%) of GPTMS functionalized mesoporous silica (F-SBA-15) through in situ polymerization process. The polybenzoxazine nanocomposites were characterized using X-ray powder diffraction and scanning electron microscopy. In addition Surface treated (F-SBA-15) dispersed polybenzoxazine nanocomposites has been prepared and studied for their N2 adsorption/desorption, water contact angle, dielectric behavior and anticorrosive properties. The polymer nanocomposites subjected to the highest water contact angle noted at 115° was attained for 10 wt% (F-SBA-15). The value of dielectric constant for neat, 1, 5, 10 wt% (F-SBA-15) incorporated polymer nanocomposites was noted as 4.7, 3.8, 2.9, and 2.1, respectively. The corrosion resistant capacity of BZ/(F-SBA-15), on mild steel specimens, was noticeably higher than that of conventional polybenzoxazine due to the hydrophobic aliphatic chain segments and porous structure of (F-SBA-15). [ABSTRACT FROM AUTHOR]

Poly(aryl ether) materials are used in a wide range of applications in the communications and microelectronics fields for their outstanding mechanical and dielectric properties. In order to further improve the comprehensive performance, this work reports a series of cross-linkable poly(aryl ether)s (UCL-PAEn) containing trifluoroisopropyl and perfluorobiphenyl structures using 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2'-diallyl bisphenol A, and perfluorobiphenyl as starting materials. Their chemical structures and the effect of changes in the allyl content on the properties are thoroughly investigated. Owing to the introduction of fluorine atoms and cross-linked networks, the cross-linked poly(aryl ether) films present low dielectric constants ( D k = 1.93-2.24 at 1 MHz), low water absorption (0.14% -0.25%), and hydrophobic film surfaces (94.3-99.4°). Additionally, because of the presence of cross-linked networks, the CL-PAEn films exhibit superior thermal stability, with the 5% weight loss temperatures all above 445 °C and the maximum thermal decomposition rate temperatures all above 550 °C. The cross-linked films also demonstrate excellent mechanical properties, with tensile strength in the range of 57.1 -146.7 MPa and tensile modulus in the range of 1.8 GPa-4.5 GPa.

The sintering and dielectric properties of (1 − x)Li2Mg0.95Co0.05SiO4 + xTiO2 ceramics created by the solid state reaction method were investigated. X-ray diffraction and energy-dispersive X-ray spectroscopy were used to obtain phase composition of the ceramics, and scanning electron microscopy was used to observe their microstructure. A network analyzer was used to measure dielectric properties, while mechanical, simultaneous-thermal, and dynamic mechanical analyzers were used to obtain mechanical and chemical properties. Li2Mg0.95Co0.05SiO4 (LMCS) and TiO2 co-exist in the composite system. TiO2 addition resulted in decreasing grain size and crystallite size, increasing starting temperature of shrinkage, increasing activation energy, and increasing elasticity and stiffness. A 4%/volume addition of TiO2 and sintering at 1075 °C changed the LMCS τf to 1.57 ppm/°C and resulted in dielectric properties of εr = 6.33 and Q × f = 17,000 GHz (16 GHz) with a relative density equals to 96.13%.

A series of epoxy resins containing various trifluoromethyl groups were synthesized and thermally cured with diaminodiphenylmethane (DDM) and aminophenyl sulfone (DDS). All epoxy resins exhibited excellent thermal stability with the glass transition temperatures of above 128 °C and 5% weight loss temperatures of above 300 °C. DDS-cured epoxy resins possessed higher thermal stability than that of DDM-cured epoxy resins, while DDM-cured epoxy resins showed better mechanical, dielectric, and hydrophobic properties. Additionally, DDM-cured epoxy resins with different locations and numbers of trifluoromethyl groups showed flexural strength in the range of 95.55~152.36 MPa, flexural modulus in the range of 1.71~2.65 GPa, dielectric constant in the range of 2.55~3.05, and water absorption in the range of 0.49~0.95%. These results indicate that the incorporation of trifluoromethyl pendant groups into epoxy resins can be a valid strategy to improve the dielectric and hydrophobic performance.