Preparation and properties of glass cloth‐reinforced polyimide composites with improved impact toughness for microelectronics packaging substrates

A series of glass cloth‐reinforced thermosetting polyimide composites (EG/HTPI) were prepared from E‐glass cloth (EG) and polyimide matrix resins. The polyimide resins were derived from 1,4‐bis(4‐amino‐2‐ trifluoromethyl‐phenoxy)benzene, p‐phenylenediamine, diethyl ester of 3,3′,4,4′‐benzophenonetetracarboxylic acid, and monoethyl ester of cis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid. Based on the rheological properties of the B‐staged polyimide resins, the optimized molding cycles were designed to fabricate the EG/HTPI laminates and the copper‐clad laminates (Cu/EG/HTPI). Experimental results indicated that the EG/HTPI composites exhibited high thermal stability and outstanding mechanical properties. They had flexural strength of >534 MPa, flexural modulus of >20.0 GPa, and impact toughness of >46.9 kJ/m². The EG/HTPI composites also showed good electrical and dielectric properties. Moreover, the EG/HTPI laminates exhibited peel strength of ～ 1.2 N/mm and great isothermal stability at 288°C for 60 min, showing good potential for application in high density packaging substrates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites

New novel fire‐resistant and heat‐resistant cyclotriphosphazene‐containing polyimide resins were prepared in situ by the polymerization of (p‐aminophenoxy)(phenoxy)cyclotriphosphazenes with 3,3′,4,4′‐benzophenonetetracarboxylic acid or 3,3′,4,4′‐diphenylsulfonetetracarboxylic acid and a crosslink agent, 5‐norbornene‐2,3‐dicarboxylic acid and were used as polymer matrix compositing with a woven carbon fiber to prepare nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites. The thermal stability, flame retardance, morphology of the surface fracture, and some physical properties of the composites were investigated by thermogravimetric analysis, scanning electron microscopy, and a material testing system, respectively. The composites had good thermal stability, flame retardance, and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 810–818, 2003     

Tribological behavior of short‐fiber‐reinforced polyimide composites under dry‐sliding and water‐lubricated conditions

Polyimide composites reinforced with short‐cut fibers such as carbon, glass, and quartz fibers were fabricated by the polymerization of monomer reactants process. The mechanical properties of the composites with different fiber contents were evaluated. The friction and wear properties of the polyimide and its composites were investigated under dry‐sliding and water‐lubricated conditions. The results indicated that the short‐carbon‐fiber‐reinforced polyimide composites had better tensile and flexural strengths and improved tribological properties in comparison with glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. The incorporation of short carbon fibers into the polyimide contributed to decreases in the friction coefficient and wear rate under both dry and water‐lubricated conditions and especially under water lubrication because of the boundary lubrication effect of water. The polyimide and its composites were characterized by plastic deformation, microcracking, and spalling under both dry and water‐lubricated conditions, which were significantly abated under the water‐lubricated condition. The glass and quartz fibers were easily abraded and broken; the broken fibers transferred to the mating metal surface and increased the surface roughness of mating stainless steel, which led to the wear rate increasing for the glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Novel low‐dielectric‐constant copolyimide thin films composed with SiO2 hollow spheres

A series of copolyimide/SiO₂ hollow sphere thin films were prepared successfully based on bis[3,5‐dimethyl‐4‐(4‐aminophenoxy)phenyl]methane and 9,9‐bis(4‐(4‐aminophenoxy)phenyl)fluorene (molar ratio = 3 : 1) as diamine, and 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride) as dianhydride, with different wt % SiO₂ hollow sphere powder with particle size 500 nm. Some films possessed excellent dielectric properties, with ultralow dielectric constants of 1.8 at 1 MHz. The structures and properties of the thin films were measured with Fourier transform infrared spectra, scanning electron microscope, thermogravimetric analysis, and dynamic mechanical thermal analysis. The polyimide (PI) films exhibited glass‐transition temperatures in the range of 209– 273°C and possessed initial thermal decomposition temperature reaching up to 413–477°C in air and 418–472°C in nitrogen. Meanwhile, the composite films were also exhibited good mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Low‐viscosity and soluble phthalonitrile resin with improved thermostability for organic wave‐transparent composites

High processing viscosity and poor solubility limit the application of heterocyclic polymers for fabricating organic wave‐transparent composites for aerospace applications. In this paper, a novel resin, poly(phthalazinone ether bisphenol fluorene) encapped with phthalonitrile (PPEBF‐Ph), was synthesized and used as the matrix. Biphenol‐based phthalonitrile monomer BP‐Ph was also synthesized and blended with PPEBF‐Ph to further lower the processing viscosity. Solubility tests showed that the resin was soluble in dimethylformamide, N,N‐dimethyl acetamide, N‐methylpyrrolidone, dimethyl sulfoxide, chloroform, and other solvents. Differential scanning calorimetry and rheological studies revealed that the mixed resins exhibited low processing viscosity and a wide processing window below the gel temperature. Thermogravimetric analysis indicated that the cured resins were stable below 510–530 °C under nitrogen atmosphere after 6 h of curing (decreased by 40–60% compared with previous reports on phthalonitrile resin). In air, the char yields of the resins reached 20–30% when heated at 800 °C. The composites were reinforced by a quartz fiber cloth and exhibited a dielectric constant of 2.94–3.27 in an electromagnetic field with frequency ranging from 8 to 18 GHz. Retention of the bending modulus exceeded 70% at 400 °C according to dynamic mechanical analysis, indicating excellent mechanical stability was obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45976.     

Fiber Reinforced Polyimide Aerogel Composites with High Mechanical Strength for High Temperature Insulation

Glass fiber/polyimide aerogel composites are prepared by adding glass fiber mat to a polyimide sol derived from diamine, 4,4′‐oxydianiline, p‐phenylene diamine, and dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride. The fiber felt acts as a skeleton for support and shaping, reduces aerogel shrinkage during the preparation process, and improves the mechanical strength and thermal stability of the composite materials. These composites possess a mesoporous structure with densities as low as 0.143–0.177 g cm^?3, with the glass fiber functioning to improve the overall mechanical properties of the polyimide aerogel, which results in its Young's modulus increasing from 42.7 to 113.5 MPa. These composites are found to retain their structure after heating at 500 °C, in contrast to pure aerogels which decompose into shrunken ball‐like structures. These composites maintain their thermal stability in air and N₂ atmospheres, exhibiting a low thermal conductivity range of 0.023 to 0.029 W m^?1 K^?1 at room temperature and 0.057to 0.082 W m^?1 K^?1 at 500 °C. The high mechanical strengths, excellent thermal stabilities, and low thermal conductivities of these aerogel composites should ensure that they are potentially useful materials for insulation applications at high temperature.     

Bisphenol containing novel polyimides/glass fiber composites

A new diamine was synthesized using bisphenol‐A and p‐amino benzoic acid. Polyimides I and II were prepared with the diamine and pyromellitic dianhydride/3,3′,4,4′ benzophenone tetracarboxylic acid dianhydride. Bismaleimide (BMI) was synthesized using the same diamine and maleic anhydride. The prepared diamine and polyimides were characterized using FTIR. Thermo gravimetric analysis was used to study the thermal properties of synthesized polyimides and BMI. Woven glass fabric/unidirectional glass fiber‐polyimide/BMI composites were made and their properties (fiber volume fraction, density, tensile, flexural, impact, and hardness) were studied and compared with a few representative carbon fiber polyimide, carbon fiber–epoxy, and glass fiber–epoxy composites. The prepared composites were subjected to thermal aging and moisture absorption and their effects on tensile and flexural properties were studied. POLYM. COMPOS., 28: 372–380, 2007. © 2007 Society of Plastics Engineers     

Synthesis and characterization of polyimide–silica nanocomposites using novel fluorine‐modified silica nanoparticles

Polyimide–silica nanocomposites were synthesized with 4,4′‐oxydianiline, 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride), and fluorine‐modified silica nanoparticles. Fluorinated precursors such as 4″,4?‐(hexafluoroisopropylidene)bis(4‐phenoxyaniline) (6FBPA) and 4,4′‐(hexafluoroisopropylindene)diphenol (BISAF) were employed to modify the surface of the silica nanoparticles. The microstructures and thermal, mechanical, and dielectric properties of the polyimide–silica nanocomposites were investigated. An improvement in the thermal stability and storage modulus of the polyimide nanocomposites due to the addition of the modified silica nanoparticles was observed. The microstructures of the polyimide–silica nanocomposites containing 6FBPA‐modified silica exhibited more uniformity than those of the nanocomposites containing BISAF‐modified silica. The dielectric constants of the polyimide were considerably reduced by the incorporation of pristine silica or 6FBPA‐modified silica but not BISAF‐modified silica. The addition of a modifier with higher fluorine contents did not ensure a lower dielectric constant. The uniformity of the silica distribution, manipulated by the reactivity of the modifier, played an important role in the reduction of the dielectric constant. Using 6FBPA‐modified silica nanoparticles demonstrated an effective way of synthesizing low‐dielectric‐constant polyimide–silica nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 882–890, 2007     

High‐performance bismaleimide resin film for resin film infusion

A novel high‐performance resin film, coded 4508B, suitable for the resin film infusion (RFI) process, was developed. It was prepared from 4,4′‐bismaleimidodiphenylmethane (BDM), o,o′‐diallylbisphenol A (BA), polyethersulfone (PES), and polyimide (PI). The resin and its composite, reinforced by glass fiber cloth, were prepared and characterized in detail. The results showed that the resin film was stable at room temperature, its infusion temperature was 120°C, and the pot life was more than 60 min. In addition, the cured resin and the composite prepared by the RFI process had good thermal and mechanical properties and hot‐wet resistance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2918–2922, 2001     

Properties and application of polyimide‐based composites by blending surface functionalized boron nitride nanoplates

Ball milling was used to decrease the particle size of boron nitride (BN) nanoplates and to form more silylated functionalization of their surface. Such functionalized BN nanoplates enhanced their homogeneous dispersion in polyimide (PI) matrix. Thermal conductivities, thermal stabilities, and dielectric properties were characterized to investigate the particular effects on the performance of PI‐based composites with functionalized BN nanoplates. When the concentration of functionalized BN nanoplates increased to 50 wt %, thermal conductivity of the composite increased up to 1.583 W m^?1 K^?1, and the temperature of final thermal decomposition was improved to 600°C. An increasing trend was found in the dielectric constant of the composites while the dielectric loss decreased with the increase in the fraction. An appropriate fraction of functionalized BN nanoplates in PI‐based composites were necessary to meet the requirement of withstanding drilling forces for the interconnecting through holes of flexible circuits. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41889.     

Effects of some PVC‐grafted maleic anhydrides (PVC‐g‐MAs) on the morphology,and the mechanical and thermal properties of (alfa fiber)‐reinforced PVC composites

This work studied the poly(vinyl chloride) (PVC) chemically modified with maleic anhydride (MA) through reactions in solution, using benzoyl peroxide as an initiator. Quantities of the grafted MA were determined by the titration of carboxylic acid groups derived from the anhydride functions. Estimation of the grafted MA level was also performed by using IR absorbance ratio. Increases in reaction time led to higher levels of grafted MA. The effects of three different PVCs grafted with maleic anhydride (PVC‐g‐MAs) types on the morphological, mechanical, and thermal properties of PVC/alfa (fiber) composites were examined. The interfacial properties between fiber and PVC were improved after the addition of PVC‐g‐MA, as was evident from SEM morphology study. Enhancements of the mechanical properties and thermal stability of the PVC‐g‐MA‐treated composites were strongly dependent on the amount of MA grafts. J. VINYL ADDIT. TECHNOL., 19:225–232, 2013. © 2013 Society of Plastics Engineers     

Synthesis and characterization of organosoluble polyfluorinated polyimides derived from 3,3′,5,5′‐tetrafluoro‐4,4′‐diaminodiphenylmethane and various aromatic dianhydrides

A polyfluorinated aromatic diamine, 3,3′, 5,5′‐tetrafluoro‐4,4′‐diaminodiphenylmethane (TFDAM), was synthesized and characterized. A series of polyimides, PI‐1–PI‐4, were prepared by reacting the diamine with four aromatic dianhydrides via a one‐step high‐temperature polycondensation procedure. The obtained polyimide resin had moderate inherent viscosity (0.56–0.68 dL/g) and excellent solubility in common organic solvents. The polyimide films exhibited good thermal stability, with an initial thermal decomposition temperature of 555°C–621°C, a 10% weight loss temperature of 560°C–636°C, and a glass‐transition temperature of 280°C–326°C. Flexible and tough polyimide films showed good tensile properties, with tensile strength of 121–138 MPa, elongation at break of 9%–12%, and tensile modulus of 2.2–2.9 GPa. The polyimide films were good dielectric materials, and surface and volume resistance were on the order of a magnitude of 10¹⁴ and 10¹⁵ Ω cm, respectively. The dielectric constant of the films was below 3.0 at 1 MHz. The polyfluorinated films showed good transparency in the visible‐light region, with a cutoff wavelength as low as 302 nm and transmittance higher than 70% at 450 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1442–1449, 2007     

Polyimide–polydimethylsiloxane copolymers for low‐dielectric‐constant and moisture‐resistance applications

Novel, randomly coupled, soluble, segmented polyimide–polydimethylsiloxane (PI–PDMS) copolymers were prepared from aminoalkyl‐terminated polydimethylsiloxane (At–PDMS), 4,4′‐oxydianiline diamine, pyromellitic dianhydride, and 4,4′‐diphenylmethane diisocyanate (MDI). When At–PDMS was introduced into the polyimide chain, the polyimide copolymers exhibited lower dielectric constants and better moisture resistance and mechanical properties. The reductions in the dielectric constant of the PI–PDMS copolymers could be attributed to the incorporation of polydimethylsiloxane (PDMS) into the polyimide chain and the nanopores in the film generated by carbon dioxide evolvement during the reaction. The lowest dielectric constant was 2.58 with 25 wt % PDMS and 5 wt % MDI. In addition, the water contact angles of the resultant copolymers increased from 51 to 109° when the contents of PDMS increased from 0 to 25 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fiber hybrid polyimide‐based composites reinforced with carbon fiber and poly‐p‐phenylene benzobisthiazole fiber: Tribological behaviors under sea water lubrication

Fiber hybrid polyimide‐based (PI‐based) composites reinforced with carbon fiber (CF) and poly‐p‐phenylene benzobisthiazole (PBO) fiber of different volume fractions were fabricated by means of hot press molding technique, and their mechanical properties and tribological behaviors under sea water lubrication were systematically investigated in relation to the synergism of CF and PBO fiber. Results showed that the incorporation of CF or PBO fiber improved the tensile strength, hardness, and wear resistance of PI. More importantly, because of the synergistic enhancement effect between CF and PBO fiber on PI matrix, the combination of 10%CF and 5%PBO fiber reinforced PI‐based composite had the best mechanical and tribological properties, showing promising application in ocean environment. POLYM. COMPOS., 37:1650–1658, 2016. © 2014 Society of Plastics Engineers     

Novel colloidal nanofiber electrolytes from PVA‐organoclay/poly(MA‐alt‐MVE), and their NaOH and Ag‐carrying polymer complexes

Novel multifunctional polymer nanofiber electrolytes with covalence crosslinked structures from various solution blends of reactive intercalated poly(vinyl alcohol)/octadecylamine montmorillonite (as a matrix polymer), poly(maleic anhydride‐alt‐methyl vinyl ether) (as a partner polymer) and their NaOH‐absorbing and Ag‐carrying polymer complexes were fabricated via electrospinning. Chemical, physical, morphological, and electrical properties of nanofiber structures were investigated by FTIR, XRD, SEM, and electrical analysis methods. Ag precursors in fiber composites significantly improved phase separation processing, fiber morphologies, diameter distributions, and electrical properties of the fibers. In situ generation of Ag nanoparticles and their distribution on nanofiber surfaces during fiber formation occurred via complex formation between silver cations and electronegative functional groups from both matrix and partner polymers as stabilizing/reducing agents. Electrical resistance and conductivity strongly depended on matrix/partner polymer ratios and absorption time of NaOH solution on nanofibers. Addition of NaOH changed the electrical properties of fiber structures from almost dielectric state to excellent conductivity form. The fabricated unique nanofiber electrolytes are promising candidates for applications in power and fuel cell nanotechnology, electrochemical, and bioengineering processes as reactive semiconductive platforms. POLYM. ENG. SCI., 56:204–213, 2016. © 2015 Society of Plastics Engineers     

Sulfonyl‐Containing Polyimide Dielectrics with Advanced Heat Resistance and Dielectric Properties for High‐Temperature Capacitor Applications

Polymer dielectrics, with advanced dielectric properties and heat resistance, are critical for high‐temperature capacitors in various applications. However, the high performance of heat resistance and dielectric properties are quite difficult to achieve all together due to their mutual implication. Here, by intensively investigating the correlation between molecular structure and properties, polyimide dielectrics with i) enhanced dielectric constant by introducing sulfonyl group, ii) low dissipation factor by introducing flexible linkage, and iii) high T_g (glass transition temperature) by retaining an aromatic structure, are obtained. The sulfonyl‐containing polyimides with different flexible linkages exhibit simultaneously a high dielectric constant (4.50–5.98), low dissipation factor (0.00298–0.00426), and outstanding breakdown strength (most above 500 MV m^?1), as well as superior heat resistance (T_g : 244–304 °C). Specifically, the polyimide (SPI‐1) with sulfonyl group in diamine moiety and para‐para linkage shows stable dielectric properties up to 150 °C, and the discharged energy density and charge–discharge efficiency can be as high as 7.04 J cm^?3 and 91.3% at 500 MV m^?1, respectively.     

Preparation and the properties of PMR‐type polyimide composites with aluminum nitride

A new polyimide composite was developed relying on the concept of in situ polymerization of monomer reactants polyimide. High thermal conductive, low dielectric constant and dielectric loss, and thermal‐stable composites were successfully demonstrated by incorporating aluminum nitride powder into the polyimide. The weight percent of aluminum nitride was up to 80%. The thermal and dielectric properties follow the classic composite theories. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3913–3917, 2003     

Effect of monomer composition on properties of copolyimides derived from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride/4,4′‐oxydianiline/1,3‐bis (4‐aminophenoxy)benzene

A series of uncontrolled molecular weight homopolyimides and copolyimides based on 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA)/4,4′‐oxydianiline (4,4′‐ODA)/1,3‐bis(4‐aminophenoxy)benzene (TPER) were synthesized. All the polyimides displayed excellent thermal stability and mechanical properties, as evidenced by dynamic thermogravimetric analysis and tensile properties testing. A singular glass transition temperature (T_g) was found for each composite from either differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA), but the values determined from tan δ of DMA were much different from those determined from DSC and storage modulus (E′) of DMA. The Fox equation was used to estimate the random T_g values. Some composites exhibited re‐crystallization after quenching from the melt; upon heating, multi‐melting behavior was observed after isothermal crystallization at different temperatures. The equilibrium melting temperature was estimated using the Hoffman‐Weeks method. Additionally, DMA was conducted to obtain E′ and tan δ. Optical properties were strongly dependent on the monomer composition as evidenced by UV‐visible spectra. X‐ray diffraction was used to interpret the crystal structure. All the results indicated that composites with TPER composition ≥ 70% were dominated by the TPER/s‐BPDA polyimide phase, and ≤40% by the 4,4′‐ODA/s‐BPDA polyimide phase. When the ratio between the two diamines was close to 1:1, the properties of the copolyimides were very irregular, which means a complicated internal structure. Copyright © 2011 Society of Chemical Industry     

Influence of chemical structure of polyimide prepolymer on rheo‐mechanical properties of polyimide foam composites

A study is reported of the effect of varying chemical composition of foam polyimide prepolymers (H‐complex) on the structure and properties of foam polyimide resins and their composites with aromatic polyimide fiber felt. The melt rheological behavior of the H‐complex was found to be strongly dependent on its chemical composition and structure reorganization in the melt which is akin to mesophasic structural transition states in liquid crystal polymers. Changing the diamine part of the H‐complex from 4,4‐methylene dianiline to 1,3‐diaminobenzene led to decreased steady shear viscosity at temperatures and shear rates ranging between 95° and 105°C and 0.01 and 1 s⁻¹, respectively. Additionally, changing the dialkyl moiety from dimethyl to diethyl in 3,3′,4,4′‐benzophenonetetracarboxylic dialkyl ester (precursor to the H‐complex) increased gelation time of the H‐complex, enhancing processibility of the foam polyimide composites. The results indicate that novel, lightweight foam polyimide composites with enhanced thermomechanical properties for beneficial uses can be prepared through chemical modification of the H‐complex prior to its thermal imidization in the presence of the aromatic polyimide fiber felt.     

Long jute fiber‐reinforced polypropylene composite: Effects of jute fiber bundle and glass fiber hybridization

Two types of long jute fiber pellet consisting of twisted‐jute yarn (LFT‐JF/PP) and untwisted‐jute yarn (UT‐JF/PP) pellets are used to prepare jute fiber–reinforced polypropylene (JF/PP) composites. The mechanical properties of both long fiber composites are compared with that of re‐pelletized pellet (RP‐JF/PP) of LFT‐JF/PP pellet, which is re‐compounded by extrusion compounding. High stiffness and high impact strength of JF/PP composites are as a result of using long fiber. However, the longer fiber bundle consequently affects the distribution of jute fiber. The incorporation of 10 wt % glass fibers is found to improve mechanical properties of JF/PP composites. Increasing mechanical properties of hybrid composites is dependent on the type of JF/PP pellets, which directly affect the fiber length and fiber orientation of glass fiber within hybrid composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41819.