New positive-type photosensitive polyimide: poly(hydroxyimide) with diazonaphthoquinone

A positive working photosensitive polyimide based on polyhydroxyimide (PHI) and 2,3,4-tris[1-oxo-2-diazonaphthoquinone-4-sulfonyloxy] benzophenone (D4SB) as a photoreactive compound has been developed. The PHI was prepared by the ring-opening polyaddition of 4,4′-hexafluoroisopropylidenebis(phthalic anhydride) (6FDA), 4,4′-diamino-4″-hydroxytriphenylmethane (DHTM), and 4,4′-oxydianiline (ODA), followed by thermal cyclization in refluxing xylene. The PHI film showed excellent transparency to UV light. The photosensitive polyimide containing 30 wt% of D4SB showed a sensitivity of 250 mJ/cm² and a contrast of 5.2 when it was exposed to 436 nm light followed by developing with a 1% aqueous tetramethylammonium hydroxide (TMAH) solution at 35°C.     

Effects of reactive end-capper on mechanical properties of chemical amplified photosensitive polyimide

Photosensitive polyimide (PSPI) was synthesized and characterized to replace the conventional polyimide buffer layer because direct patterning with PSPI could reduce the processing procedure to the half. Since PSPI should be dissolved in alkaline aqueous solution and have good mechanical properties after imidization, low molecular weight of PSPI was synthesized with reactive end-capper, which could extend the chain length of PSPI during imidization. Therefore norbornene end-capped PSPI precursor was synthesized with various 5-norbornene-2,3-dicarboxylic anhydride (NDA) content.Although molecular weight of PSPI decrease with increasing NDA content, the elongation at break and the glass transition temperature (T_g) of PSPI films imidized at 300 °C increased with increasing NDA content. On the other hand, elongation at break of PSPI films imidized at 350 °C decreased but T_g of those increased with increasing NDA content. Above T_g, thermal expansion coefficient decreased dramatically by introducing NDA end-capper. From mechanical and thermal properties of PSPI, it appears that low molecular weight of PSPI can be chain-extended and crosslinked during imidization.     

A novel negative photoinitiator-free photosensitive polyimide

A novel negative photoinitiator-free photosensitive polyimide (PFPS-PI) was synthesized through introducing the photosensitive 4,4-bis[(4-amino)thiophenyl] benzophenone (BATPB) into backbone chain and methyl acrylate group into side-chain of the polyimide, respectively. Photosensitive properties study revealed its good photolithographic properties, with a resolution about 5 μm and a sensitivity of 150 mJ/cm².     

Synthesis and characterization of novel negative-working aqueous base developable photosensitive polyimide precursors

Through molecular designing, three poly(amic esters) (PAEs) have been synthesized from pyromellitic dianhydride (PMDA), 2,2′-bis-(3-amino-4-hydroxyphenyl) hexafluoropropane (BisAPAF), 4,4′-diaminodiphenyl ether (4,4′-ODA) and 2-hydroxyethyl methacrylate (HEMA). Due to the introduction of photosensitive acrylate groups and aqueous base soluble phenolic hydroxyl groups in the backbone, these poly(amic esters) can be used as the precursors of negative-working, aqueous base developable photosensitive polyimides (PSPIs). These poly(amic esters) were prepared by direct polymerization by using phenyl phosphonic dichloride (PPD) as an activator. The inherent viscosities of these polymers were 0.20 (dL/g). Their structures were characterized by Fourier transform infrared spectroscopy (FTIR) and ¹H NMR. In order to improve the photolithographic performance of these PSPIs, different photosensitizers, photoinitiators and a crosslinker have been added in the PSPI formulations. Among them, the Michler's ketone (MK)/tribromomethyl phenyl sulfone (TBPS) system gave the best results. Using a 2.38 wt% aqueous TMAH solution as a developer, patterns with a resolution of 10 μm were obtained from these PSPI formulations. In addition, the effects of the molecular structure of the precursors and the concentration of developer on the photosensitivity of the PSPI formulations were also discussed.     

Modification of negative auto‐photosensitive polyimide

This article describes the preparation of a kind of auto‐photosensitive polyimide (PSPI) that contains organo‐silicone moiety in its main chain. A group of novel auto‐photosensitive polyimides were prepared based on the aromatic diamine monomers and 3,3′,5,5′‐benzophenontetracarboxylic dianhydride (BTDA) by the method of solution polycondensation at room temperature and imidized at a high temperature. The properties of PSPIs, such as ultraviolet (UV) absorption, electric and adhesion properties, and moisture absorption, were characterized by UV analysis, a dielectric constant detector, and so on. The relationship between the structure and properties of PSPIs is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 943–947, 2000     

Novel positive‐type photosensitive polyimide with low dielectric constant

A novel positive‐type photosensitive polyimide (PSPI) with a low dielectric constant was developed. The PSPI system was composed of soluble block PI (Bco‐PI) with a hydroxy group and diazonaphthoquinone as a photoreactive compound. The base Bco‐PI was prepared by a direct one‐pot polycondensation of 2,2‐bis(3‐amino‐4‐hydroxy‐phenylhexafluoropropane), 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane, and cyclohexanetetracarboxylic dianhydride in the presence of a γ‐valerolactone and pyridine catalyst system using N‐methyl‐2‐pyrrolidone as the solvent. The film of Bco‐PI was colorless and transparent, both important factors for a PSPI. Photosensitive soluble block PI (Bco‐PI), containing 20 wt % ester of 2,3,4‐trihydroxybenzophenone with 1,2‐naphthoquinone‐(2)‐diazide‐5‐sulfonic acid (NT200), showed a sensitivity of 350 mJ/cm² and a contrast of 1.20 when it was exposed to UV light, followed by development with 5% tetramethylammonium hydroxide aqueous solution at room temperature. The estimated optical dielectric constants of the PIs with and without NT200 were 2.68 and 2.75, respectively. These values were significantly lower than those of conventional aromatic PIs, such as Kapton film (50EN). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 15–21, 2005     

Synthesis and characterization of low‐dielectric photosensitive polyimide/silica hybrid materials

Photosensitive polyimide/silica hybrid materials were synthesized by reaction between 4,4′‐hexafluoroisopropylidene diphthalic anhydride (6FDA) and 4,4′‐oxydianiline. The intrachain chemical bonding and the interchain hydrogen bonding between the polyimide and silica moieties were increased by the incorporation of 2‐(dimethylamino) ethyl acrylate and 3‐aminopropyl trimetho xysilane, respectively. The photoinitiator was bis(2,4,6‐trimethyl benzoyl) phenylphosphine oxide (Irgacure‐819). The various coupling agents were utilized included tetrakis (allyloxy) silane (TAL). Most silica hybrid films showed better volume shrinkage and temperature resistance. The cooperation of octavinyl POSS, as the coupling agent, can lower dielectric constant (k) down to 2.48 but with the poorer volume shrinkage and temperature resistance than the other silica hybrid films. The addition of tetramethyl orthosilicate and 3‐methacryloxy propyltrimethoxysilane with silica content of 5.6 wt % can reduce k down to 2.26 but with worse volume shrinkage than the incorporation with TAL. The TAL hybrid film with degree of polymerization of 25 showed the best properties that optimized photolithography, dielectric constant (k = 3.81), volume shrinkage, and temperature resistance (Td5% = 378°C) with only 0.22 wt % silica content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A chemically amplified positive-working photosensitive polyimide based on a blend of poly(amic acid ethoxymethyl ester) and poly(amic acid)

We prepared a novel chemically amplified photosensitive polyimide based on a blend of poly(amic acid ethoxymethyl ester) (PAAE) and poly(amic acid); this blend produces polyimide (PI) films with improved mechanical properties after imidization with photoacid generator (PAG). PAAE and poly(amic acid) were end-capped with 5-norbornene-2,3-dicarboxylic dianhydride and 2,3-dimethyl maleic anhydride, respectively, to lower their molecular weights without compromising the properties of the resulting PI films. As a result of the blending of these PI precursors, the mechanical properties of the PI films were found to be less affected by the strong acid generated from the PAG than PI films fabricated by imidization of PAAE alone. The relatively high solubility of the blended PI precursor film in basic aqueous solutions was found to be effectively controlled by the use of a high-temperature post-exposure bake process to partially imidize the end-capped PAA. It was found that a 10-μm-thick film of the PSPI precursor system containing 13 wt% PAGs exhibits a sensitivity (D⁰) of 700 mJ/cm² when developed with 2.38 wt% aqueous tetramethyl ammonium hydroxide solution at room temperature. A fine positive pattern was fabricated in a 12 μm thick film with 1000 mJ/cm² of i-line exposure. The resultant PI film was also found to exhibit excellent mechanical and thermal properties, which are critical to its practical use as a stress buffer layer in semiconductor packaging.     

Preparation and characterization of polyimide/modified layered double hydroxide nanocomposites

Polyimide (PI)/modified layered double hydroxide (m‐LDH) nanocomposites were prepared in this study. For this work, m‐LDHs were prepared from layered double hydroxides (LDHs) through an anionic exchange reaction with pyromellitic dianhydride (PMDA), succinic acid or terephthalic acid. PMDA and 4,4′‐oxydianiline were used to make the poly(amic acid) precursor for PI. X‐ray diffraction and transmission electron microscopy measurements confirmed that the PMDA‐modified LDH (PMH) and terephthalic acid‐modified LDH (TMH) were well dispersed in the PI matrix. For the succinic acid‐modified LDH, some of the LDH was intercalated with the succinic acid molecules but most maintained its original structure. Thus, the PI/PMH and PI/TMH nanocomposites exhibited improved mechanical, thermal and electrical properties compared to pure PI. The PMH has aromatic groups and is expected to have better π–π interactions with the PI chains than the other m‐LDHs. Thus, the PI/PMH nanocomposites exhibited the best properties among the nanocomposites investigated. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of a positive‐working,aqueous‐base‐developable photosensitive polyimide precursor

A positive‐working, aqueous‐base‐developable photosensitive polyimide precursor based on poly(amic ester)‐bearing phenolic hydroxyl groups and a diazonaphthoquinone photosensitive compound was developed. The poly(amic ester) was prepared from a direct polymerization of 2,2′‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and bis(n‐butyl)ester of pyromellitic acid in the presence of phenylphosphonic dichloride as an activator. Subsequently, the thermal imidization of the poly(amic ester) precursor at 300°C produced the corresponding polyimide. The inherent viscosity of the precursor polymer was 0.23 dL/g. The cyclized polyimide showed a glass‐transition temperature at 356°C and a 5% weight loss at 474°C in nitrogen. The structures of the precursor polymer and the fully cyclized polymer were characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. The photosensitive polyimide precursor containing 25 wt % diazonaphthoquinone photoactive compound showed a sensitivity of 150 mJ/cm² and a contrast of 1.65 in a 3 μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 10 μm was obtained from this composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 352–358, 2002     

A positive‐working photosensitive polyimide based on thermal cross‐linking and acidolytic cleavage

A novel positive‐working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three‐component PSPI was synthesized from 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane through ring‐opening polymerization and subsequent thermal cyclization. 2,2′‐bis(4‐(2‐(vinyloxy)ethoxy)phenyl)propane (BPA‐DEVE) was used as a vinylether compound and diphenyliodonium 5‐hydroxynaphthalene‐1‐sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA‐DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA‐DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 μm in a 3.7‐μm‐thick film was obtained from the three‐component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of diazonaphthoquinone groups on photosensitive coating

Diazonaphthoquinone (DNQ)‐novolak photosensitive materials are important in lithography. DNQ groups play an important role in the photosensitive coating. However, there are no reports on the relationship between content of DNQ groups and properties of the coating. The properties include alkali resistance, isopropanol resistance, and abrasion resistance, the key factors in lithography. The experimental results show proper content of DNQ groups can ensure higher sensitivity, finer resolution, and better abrasion resistance in lithography. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Structure–property relationship of polyimide fibers containing ether groups

The copolyimide (co‐PI) fibers with outstanding mechanical properties were prepared by a two‐step wet‐spinning method, derived from the design of combining 4,4′‐oxydianiline (ODA) with the rigid 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)/p‐phenylenediamine (p‐PDA) backbone. The mechanical properties of PI fibers were drastically improved with the optimum tensile strength of 2.53 GPa at a p‐PDA/ODA molar ratio of 5/5, which was approximately 3.7 times the tensile strength of BPDA/p‐PDA PI fibers. Two‐dimensional wide‐angle X‐ray diffraction indicated that the highly oriented structures were formed in the fibers. Two‐dimensional small‐angle X‐ray scattering revealed the existence of the needle‐shaped microvoids aligned parallel to the fiber axis, and the introduction of ODA led to the reduction in the size of the microvoids. As a result, the significantly improved mechanical properties of PI fibers were mainly attributed to the gradually formed homogeneous structures. The co‐PI fibers also exhibited excellent thermal stabilities of up to 563°C in nitrogen and 536°C in air for a 5% weight loss and glass transition temperatures above 279°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42474.     

含氰基聚酰亚胺薄膜的制备及其热分解动力学

以4-[3,5-双(4-氨基苯氧基)苯氧基]邻苯二甲腈和3,3′,4,4′-联苯四甲酸二酐为原料,经聚酰胺酸热酰亚胺化制备含氰基的聚酰亚胺(CN-BP-PI)薄膜。采用傅里叶变换红外光谱、热重分析、差示扫描量热法对CN-BP-PI薄膜进行了分析。采用动态热重法研究了CN-BP-PI的分解动力学,用积分法结合常见固相热分解反应动力学函数来判断热分解的动力学函数。由Ozawa,KAS,Kissinger,Achar,Coats-Redfern,MacCallum-Tanner,van Krevelen方程求热分解反应的动力学参数。转化率为0.2~0.8时所得CN-BP-PI在氮气中热分解反应的表观活化能为119.68~215.61 kJ/mol,平均活化能为136.35 kJ/mol,指前因子平均值为8.52×107 s-1。     

New polyimide nanocomposites based on silicate type nanotubes: Dispersion, processing and properties

Novel magnesium hydrosilicate [Mg₃Si₂O₅(OH)₄] nanotubes (SNTs) were synthesized and used as fillers for polyimide nanocomposites. New polymer nanocomposites containing SNTs and polyimide matrices such as PMDA-ODA (denoted by PI_PAA-PM) and Ultem^®-1000 were prepared with SNT concentrations ≤12 vol% (or ∼20 wt%) to yield new materials with improvements in stiffness, strength and barrier properties. It was found that the SNT particles can be readily dispersed homogeneously in the polyimide matrices by using a special solvent mixing/casting method (PI_PAA-PM films) and melt-blending method (Ultem^®-1000 thermoplastic nanocomposites) at elevated temperatures that are well below the thermal degradation temperature of the SNT particles.The PI_PAA-PM/SNT and ULTEM^®-1000/SNT nanocomposites exhibited significant improvements in mechanical properties with increasing SNT concentrations, as well as adequate strain to failure (or ductility). Dielectric and gas barrier measurements of the polyimide nanocomposites revealed a reduction in the dielectric constant and improvements in the gas barrier properties as a function of the SNT concentration. The gas barrier behavior was found to be consistent with the Nielsen's equation and the expansion approximation equation reported by Fredrickson and Shaqfeh. Because of their facile synthesis and desirable properties for a number of applications in protective coatings and films for microelectronic applications and flammability reduction, these polyimide nanocomposites are expected to be excellent model systems for exploring mechanisms of reduction in dielectric constant of polyimides filled with hollow nanoscale inorganic tubes, a very important and desirable characteristic in microelectronic applications.     

Synthesis and properties of optically active substituted polyacetylenes having carboxyl and/or amino groups

Polyacetylenes having carboxyl and/or amino groups in the side chain were synthesized by the polymerization of N-(2-propynyloxycarbonyl)-l-alanine (1) and l-alanine N-propargylamide (2) catalyzed with a rhodium cation complex. Poly(1_0.5-co-2_0.5) exhibited a larger CD signal than the homopolymers. The polymer mixtures obtained by the polymerization of 1 in the presence of poly(2), and those obtained by the polymerization of 2 in the presence of poly(1) showed specific rotations larger than calculated. The polymerization of propargylamine in the presence of poly(1) did not exhibit significant effect, while the polymer mixtures obtained by the polymerization of propiolic acid in the presence of poly(2) exhibited [α]_D of positive sign, although poly(2) alone exhibited [α]_D of negative sign.     

Facile modifications of polyimide via chloromethylation: II. Synthesis and characterization of thermocurable transparent polyimide having methylene acrylate side groups

From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry     

A novel positive‐type photosensitive polyimide having excellent transparency based on soluble block copolyimide with hydroxyl group and diazonaphthoquintone

A novel positive‐type photosensitive polyimide having excellent transparency based on soluble block copolyimide (Bco‐PI) with hydroxyl group and diazonaphthoquinone (DNQ) as a photoreactive compound was developed. The base Bco‐PI A was prepared by a direct one‐pot polycondensation of cyclohexanetetracarboxylic dianhydride (H‐PMDA), 2,2‐bis(3‐amino‐4‐hydroxyphenylhexafluoropropane) (Bis‐AP‐AF), and bis(4‐(3‐aminophenoxy)phenyl)sulfone (m‐BAPS) in the presence of a γ‐valerolactone and pyridine catalyst system by using dipolar aprotic solvent such as N‐methyl‐2‐pyrrolidone (NMP).The wholly aromatic polyimides have strong absorptions in the visible regions, because of their change–transfer complex formation. On the other hand, alicyclic dianhydride, H‐PMDA, contributed to the resulting Bco‐PI film with colorlessness and transparency, which are the important factors for a photosensitive polyimide. Photosensitive Bco‐PI, containing 20 wt % 1,2‐naphthoqiunonediazide‐5‐sulfonic acid p‐cresol ester (PC5), showed a sensitivity of 250 mJ/cm² and a contrast of 2.56 when it was exposed to UV light, followed by development with 5% tetramethylammonium hydroxide (TMAH) aqueous solution at room temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1619–1624, 2005     

High thermal stable thermoplastic-thermosetting polyimide film by use of asymmetric dianhydride (a-BPDA)

In order to obtain thermoplastic (before curing) and thermosetting (after curing) polyimides with high T_g for adhesive film, we prepared novel polyimides having phenylethynyl group in the side chain (44% of concentration of curing group) from asymmetric 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), 3,4′-oxydianiline (3,4′-ODA) or 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB) or 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB), and 2,4-diamino-1-(4-phenylethynylphenoxy)benzene (mPDAp). Among three kinds of polymer, uncured polyimide of a-BPDA/1,3,4-APB; mPDAp had rather high T_g (265 °C, DMA) and thermoplasticity (E′ drop>10³ at T_g). After curing reaction of phenylethynyl group, the T_g of the polyimide was increased dramatically (364 °C, DMA). The polyimide derived from 1,3,4-APB having less concentration of curing group (20%) was also prepared to improve further film flexibility and toughness.     

Synthesis of copolyesters having tertiary amine groups or zwitterion moieties in the main chain

Copolyesters having tertiary amine groups or zwitterion moieties in the main chain were prepared from terephthaloyl chloride (TPC) and mixtures of bisphenol A and aliphatic diols such as N-ethyldiethanolamine (EDA), N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) and N,N-bis(2-hydroxyethyl)glycine (BHG) by a liquid/solid biphase polycondensation in trimethyl phosphate (TMP) as well as a water phase/organic phase interfacial polycondensation. The composition of copolymers obtained by the biphase polycondensation is close to that of the feeds. The nucleophilicity of hydroxyl groups of these aliphatic diols is increased in TMP and the solvent TMP participates in the reaction. In the water phase/organic phase interfacial polycondensation, the copolyester (P1) from EDA has a higher aliphatic diol residue content than P2 and P3 from BES and BHG, because the self-nucleophilic catalysis of the tertiary amine groups of the resulting polymer occurs in the organic phase. The copolyesters (P2 and P3) having pendant hydrophilic groups contain very few aliphatic diol residues because the self-nucleophilic catalysis of the tertiary amine groups takes place in the water phase and the extensive hydrolysis of the intermediate occurs, which results from TPC with the tertiary amine groups during the reaction.