Papers by Keyword: Polyimide

Paper TitlePage

Authors: Mun Seop Song, Chong Seung Yoon, Young Ho Kim
Abstract: Cu oxide nanoparticles were formed by reacting with Polyamic acid (PAA) with Cu during imidization. In this paper, we investigated the effect of holding time during curing on the Cu oxide nanoparticle formation. Cu thin films were deposited on SiO2/Si substrates by thermal evaporation. Polyamic acid was then spin-coated on the Cu thin film. The polyamic acid films were soft-baked at 135°C for 30 minutes and thermally cured at 350°C with various holding time in a nitrogen atmosphere. The size of the Cu2O nanoparticles formed in the polyimide (PI) matrix increased as the holding time increased. The size and distribution of Cu oxide particles were characterized using Transmission Electron Microscope (TEM). The degree of imidization of PI also increased proportional to the increase in holding time. The degree of PI imidization was analyzed by Infrared (IR) spectroscopy. Very uniform Cu2O particles less than 5 nm in size with particle density greater than 2×1012/cm2 were fabricated by controlling the holding time during curing.
Authors: Yang Yang, Di Yin, Xuan Wang, Fu Qiang Tian, Qing Quan Lei, Jing Shi, Rui Xiong
Abstract: Corona aging of 100CR polyimide (PI) film under bipolar pulse voltage was studied by using atomic force microscopy (AFM) and Confocal Raman microspectroscopy. AFM results show that the 100CR film near the breakdown hole is much rougher than the outside region. In the region away from the breakdown hole, no Raman shift is detected, but the intensity of all Raman peaks shows clearly decrease with the measuring region approaching more closely to the aging center. It is suggested that the damage of the PI film initiates from the surface in the presence of voids due to the partial discharge, and then gradually extends to interior, and these partial discharge cause progressive deterioration, and ultimately lead to the electrical breakdown of PI film with continuous aging.
Authors: Ming Yu Han, Yu Dong Feng, Yi Wang, Zhi Min Wang, Hu Wang, Kai Zhao, Xiao Mei Su, Miao Yang, Xue Lei Li
Abstract: CIGS thin film solar cells on polyimide substrate was a significant developmental direction of solar cells and fabricating high quality CIGS thin film in low temperature was its pivotal technology. The development of manufacturing the CIGS thin film solar cells on polyimide substrate in low temperature was described. The specific principle, manufacturing technique and application prospect were also involved. The problem should be solved in the future progress of CIGS thin film on polyimide substrate was illustrated.
Authors: Akira Ishida, Morio Sato
Abstract: Ti-Ni-Cu shape memory alloy (SMA) thin films were sputter-deposited on heated polyimide substrates. The (Ni,Cu) rich Ti-Ni-Cu films deposited at a substrate temperature of 543 K were found to possess a high martensitic transformation temperature above room temperature over a wide range of Cu content from 7 to 23 at%, which allows stable production of actuators that operate at room temperature. Additional deposition of a Cu film onto the Ti-Ni-Cu films facilitated the soldering of wires onto the actuators and also decreased the power consumption and response time of the actuator. The force of a polyimide/Ti-Ni-Cu SMA actuator could be increased merely by increasing the thickness of the polyimide film. An actuator composed of a 125 m thick polyimide film and an 8 m thick TiNiCu film was able to lift a 13.5 g weight. Furthermore, a Ti-Ni-Cu film could be pattern etched on a polyimide film to produce a circuit. The results indicate that a polyimide/SMA film actuator is a promising simple actuator that can be produced by simply cutting out an appropriately shaped piece with scissors or by punching and then connecting the two edges to a battery by soldering.
Authors: Luciano Arruda, Cristiano Coimbra, João Marco Andolfatto
Abstract: This work is related to reliability of strain measurement in flexible printed circuit boards (fPCBs) made with polyimide substrate. It was observed that the fPCBs are very sensitive to strain mounting stiffness. The indirect measurement method will be done employing High Speed Camera (HSP). The direct method will be formulated in two ways: 1) conventional strain gauge glued in an fPCBs; 2) printed strain gauge in a polyimide substrate. This paper will point out mistakes and show advantages when using different method to extract the deformation field of the selected area in a flexible thin film.
Authors: Jae Ho Lee
Abstract: As electronic devices are getting smaller and lighter, the density of copper lines on flexible printed circuit board (FPCB) is getting higher. Conventionally, subtractive method was used for copper line on a flexible films, however, as the line pitch is getting smaller, the lateral etching of copper cause serious problem. To replace the subtractive method, semi-additive method was used for fine pitch copper line fabrication. In semi additive process, sputtered layer for the electroplating copper was required. The feasibility of electroless plating to replace high cost sputtered copper seed layer was investigated. Electroless depositions of copper were conducted on different substrate to find optimum conditions of electroless copper plating. To find optimum conditions, the effects and selectivity of activation method on several substrates were also investigated. The adhesion strength between polyimide and copper was improved by treating the polyimide surface with butylamines. Pretreatment prior to electroless plating is very sensitive and surface dependent. Surface morphologies were investigated with FESEM.
Authors: Shu Wang Duo, Mi Mi Song, Ting Zhi Liu, Chang Yuan Hu, Mei Shuan Li
Abstract: A novel polyimide (PI) hybrid nanocomposite containing polyhedral oligomeric silsesquioxane (POSS) had been prepared by copolymerization of octa(aminophenyl)silsesquioxane (OAP-POSS), 4,4’ -oxydianiline (ODA), and pyromellitic dianhydride (PMDA). The AO resistance of these POSS/PI hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces have been characterized by X-ray photoelectron spectroscopy and FTIR. The XPS data indicate that the carbon content of the near-surface region is decreased from 63.6 to 19.3 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increase after AO exposure. The data reveal the formation of a passive inorganic SiO2 layer on the POSS/PI hybrid films during the AO exposure, which serves as a protective barrier preventing further degradation of the underlying polymer with increased exposure to the AO flux. SEM images showed that the surface of the 10 wt% POSS/PI became much less rough than that of the pristine polyimide. The AO resistance of the POSS/PI hybrid films is up to several tenfold than that of the pristine polyimide.
Authors: Shu Wang Duo, Mi Mi Song, Ting Zhi Liu, Mei Shuan Li
Abstract: To improve the AO erosion resistance of siloxane coating, the Si ion implantation with nominal dosage of 7×1016 ions/cm2 in siloxane coatings on the polyimide substrate was carried out by using the plasma immersion ion implanter. The Si implanted siloxane coatings before and after AO exposure in the ground-based AO simulation facility were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). The results of mass measurement shown that, in initial stage of AO exposure the implanted sample had a small mass change, and then was stabilized. The erosion yield of the implanted siloxane coating decreased by a factor of more than two orders of magnitude compared with that of the polyimide film, and decreased by a factor of more than an order of magnitude than that of unimplanted siloxane coatings. The results through SEM and XPS indicated that a continuous high-quality protective SiO2 surface layer was formed on the implanted siloxane coatings after the AO exposure. It can prevent further degradation of the underlying polymer with increased exposure to the AO flux and provide high-quality erosion protection for these materials. The Si implanted materials have a markedly increased erosion resistance than unimplanted siloxane coatings in AO environment.
Authors: Gai Zhao, Qi Hua Wang, Irina Hussainova, Qing Jun Ding
Abstract: Polyimide (PI) composites have been widely used in a space science due to extraordinary properties, such as excellent mechanical and electrical properties, good thermal stability and chemical inertness, as well as high wear resistance. However, atomic oxygen (AO), as one of the main radiated constituents in low earth orbit, had an important influence on the structrural and tribological properties of the polyimide matrix. To investigate the mechanism of AO erosion on polyimide, MoS2/Al2O3/PI composites were fabricated by means of a hot-press molding technique and irradiated by AO in a ground-based simulation system. The chemical composition change of the irradiated surface was examined by X-ray photoelectron spectroscopy (XPS). Then, the friction and sliding wear behavior against GCr15 steel balls were evaluated in a ground-based simulation facility using ball-on-disk tribology test rig. The worn morphologies and radiated surfaces of the materials were observed by Scanning electron microscope (SEM) to reveal the wear mechanism. Experimental analysis indicated that oxidation induced by AO irradiation and degradation of PI molecular chains on the composite’ surface results in change in chemical composition and formation of “carpet-like” structures. Affected layer, gradually formed during the process of irradiation, plays an important role for wear performance of the materials increasing friction coefficient and wear rate. Incorporation of Al2O3 nanofibers and MoS2 nanoparticles is shown to be favourable for AO resistance, which is helpful for improvement in wear resistance of the PI.
Authors: Xing Zhao, Jin Hua Yin, Rong Jin, Jin Yu Dong
Abstract: Polymer/TiO2 nanocomposite films have good mechanical, electrical and thermal property, which are applied to electrical engineering and microelectronic technique field extensively. Nano-TiO2 has bigger permittivity and better absorption ultraviolet. The PI/TiO2-PI-PI/TiO2 three layer composite films (30mm) with different content and interlayer thickness were prepared via in-situ dispersion polymerization in this paper. And the films with A (5mm), B (10mm) and C (15mm) interlayer PI thickness are divided into three different series. The results show that inorganic TiO2 nanoparticles are well dispersed in the polymer matrices. And the structures of three layers are obvious. The doped nanoparticles don’t affect the imidization of PI matrix in composite films. The time-to-breakdown of all series films increases with the TiO2 content increasing, in which the B series films possess the best performance. Besides, the B series films with 4% doping content are tested with the longest time-to-breakdown, which is three times more than that of pure PI. After corona aging, there are lots of TiO2-particles with the ability of absorbing UV accumulated on the surface of films, playing the role in shielding electric field, which is one factor resulting in improvement of corona-resistance in the composite films.
Showing 21 to 30 of 154 Paper Titles