The device produced by IC planar process only shows in 2D, therefore, many applications may be limited. When adopted the micro hinge and self-assembly of surface micro machining technology, 3D micro structure is coming true. Even though , it¡¦s hard to applied on micro fan this kind of producing continuous steps, further problem is waiting to solve. The traditional micro fan technology using surface tension power of the solder ball to carry out the purpose of self-assembly. Currently the diameter of solder ball smaller than 100£gm is fairly difficult, using photosensitive polyimide to form a elastic joint replaces the solder ball, that slashes micro fan size. Therefore PI has very good property resisting organic solvent, hence it¡¦s quiet suitable for using wet release, so that to achieve the purpose of cost down, process integrated and reducing the complex of process. Through the experiment, the optimal recipe has been done. Micro blade has raising to 45¢X, blade area can reach 200£gm¡Ñ200£gm, yield is over 50%. After observation, the key process is reflow temperature of polyimide thin film being micro structure joint, reflow temperature over 405¢J will result in thin film shrinking strongly, and that is unable to raise blade successfully.

Stuttgart, Univ., Diss., 2003.

µL

1x8 optical power splitters on silicon substrate were successfully fabricated based on polyimide channel waveguides structure. The 1x8 power splitter was first designed by bean propagation method. The device was fabricated using polyimide provided by Eternal chemistry. The TE propagation loss of the waveguide is 1.4dB with a index contrast of 0.73%. However, the waveguide is not able to support low-loss propagation of TM polarized light. The chip size of the 1x8 power splitter is 17mm x 3mm. After fabrication, the optical characteristics of the splitter were measured.

Polyimide/clay nanocomposites were synthesized via two processes. The one-step process is a polymer-diffusion process, and the two-step process is a monomer-diffusion/in-situ polymerization process. Effect of clay loading, surfactant, solvent-release, and clays on the structural formation and properties of the hybrids were studied. XRD (X-ray-diffractometer), TEM (transmission electron microscopy), FTIR (Fourier-transform infrared spectroscopy), DLS (dynamic light scattering), TGA (thermo-gravimetric analyzer), TMA (thermo-mechanical analyzer), DMA (dynamic mechanical analyzer), and GPA (gas permeability analyzer) were used for the characterization of the clays and composites. For the effect of clay-loading, it is found that the threshold of clay loading capable of efficiently improving the properties of polyimide (PI) matrix, should be larger than 0.08 ~ 0.31 wt% for the clay with aspect ratio of 200 ~ 50, as judged by the calculation of classical excluded volume argument. For the effect of surfactant, a thermally stable organoclay of 1-methyl-3-octyl-imidazolium chloride modified montmorillonite (8M) displayed the degradation temperature at maximum rate (Td.max) 91 0C higher than that of dodecyl-amine hydrochloride modified montmorillonite (12M). For PI8M hybrid with 5 wt% clay loading, the T10% Loss and Td.max increased 4 0C and 15 0C respectively as compared to that of the neat PI. Besides, two organoclays with improved affinity to solvent NMP (N-methyl-2-pyrrolidone) 18M {octadecylmethyl-bispolyoxylene [15] ammonium chloride modified montmorillonite} and 30B (Methyltallow-bis-2-hydroxyethyl ammonium ion modified montmorillonite) were used to prepare PI/clay nanocomposites. The relative oxygen permeation rate decreased to 0.5 upon the incorporation of these organoclays of 1 wt%, displaying superior improvement on the gas barrier property of polyimide. For the solvent-release effect, the intercalation behavior of the structural formation of PI/clay nanocomposites was studied. The reduction of d-spacing (~1.30 nm) of clay exists in PI/clay nanocomposites even with the case of 1 wt% clay-loading as characterized by XRD and TEM observation. An opposite argument was presented about the explanation to the contraction in galleries of clay with d001~1.30 nm for PI/clay nanocomposites, after the examination of PAA/clay, organoclay/NMP, organoclay, and pristine clay subjected to a specific heating process. We suggest this phenomenon cannot be ascribed to a poly(amic acid) monolayer adopts a flattened conformation is intercalated in the gallery upon thermal elimination of the solvent. And found it is irrelevant to the intercalation of PAA or PI molecules, but is primarily in consequence of the out-flow NMP together with the out-bound surfactants molecules, partial degradation of surfactants, and the re-aggregation of clays induced by the increasing concentration (volume fraction) of clays upon evaporation of NMP. For the effect of different methods of preparation, PI/clay nanocomposites prepared by monomer-diffusion into non-reactive clay (M) process show the higher relative oxygen permeation rate of 0.1, and Td.max of 11 0C as compared to that of hybrids synthesized by polymer-diffusion process. For the effect of different clays, properties of PI/clay nanocomposites prepared by a reactive layered silicic acid of hydrogen-magadiite (H) and nonreactive clay of montmorillonite were studied. The latter displayed a higher Td.max of 7 0C, and the lower relative oxygen permeation rate of 0.07 as compared to the former, demonstrating the better improvement on thermal, and gas barrier properties.

In this study, we extend the rigidity and resonance of benzobisthiazole for the application as second-order nonlinear optics. A novel nonlinear optical polyimide (NLO-PI) containing side-chained benzobisthiazole- based chromophore has been synthesized. A hydroxyl- containing PI (W2) was prepared using direct thermal imidization of 4,4'-diamino-4"- hydroxytriphenylmethane(DHTM) and 4,4¡¦-(hexafluoroisopropylidene) diphthalic anhydride; the benzobisthiazole-based chromophore was then prepared using 2,5-diamino-1,4- benzenedithiol dihydrochloride as the starting monomer. The final NLO-PI was obtained by the Mitsunobu reaction via ether linkage between W2 and the chromophores. This ether linkage is expected to provide chain flexibility for better orientation under electric field during poling. The C=C bonds inside the chromophores also provide more orientation probabilities and conjugation length. Formation of benzobisthiazole-based chromophore and the corresponding NLO-PI was evidenced by FTIR and UV-vis spectra. TGA reveal a thermal decomposition temperature as high as 350oC, respectively. The electrooptic coefficient of the NLO-PI at a wavelength of 830nm was found to be r33=9.75 pm/V.

Based on a series of study to improve the electrooptic coefficient (r33) of nonlinear optical polyimides (NLO-PI) containing benzobisthiazole- based chromophores in our lab, this work concentrated on the modification of the benzobisthiazole-based chromophore VIII (r33 = 6.62 pm/V). At first, a hydroxyl-containing polyimide was first synthesized by using dianhydride and diamine as reactants via thermal imidization and the benzobisthiazole-based chromophores were synthesized by using DABDT as the starting monomer. The NLO precursors were obtained by the Mitsunobu reaction via ether linkage between PI and chromophore; it was then cured at 300¢J to result in the final NLO-PI. The benzobisthiazole-based chromophore of VIII was modified with an insertion of the ethoxy group between the NLO moiety and the main PI backbone to get the NLO-V-1. This method makes the chromophore easier to orient under the electric field during poling; thus a higher r33 (7.4 pm/V) is ensured. NLO-V-2 is another modified sample which had a phenyldiazene group inserted into the chromophore of VIII to increase the conjugated length; this results in a red shifts from 390 nm (VIII) to 484 nm in UV-abs spectrum but the r33 (5.8 pm/V) has only a slight improvement.

Abstract Physical chemistry and microstructure of polyimide / clay nanocomposites were investigated in this study. Diffusion of diamine monomers into the clay gallery prior to polymerization was carefully controlled in order to demonstrate the physical constraint during the formation of the nanocomposites. In addition, diamines with different chemical reactivity were employed to show the effect of chemical reaction on the resultant composites. The microstructure and morphology were identified with X-ray diffraction (XRD) and transmission electron microscopy (TEM), while thermal gravimetric analysis (TGA) was performed to demonstrate the thermal stability of the composites. XRD and TEM results indicate that the final properties and microstructure of the PI / clay nanocomposites were profoundly affected by both the diffusion and chemical reactivity of the monomers prior to the formation of polyamic acid and the subsequent thermal imidization had almost no effect. It should be emphasized that diffusion and chemical reactivity of the monomers are highly competitive. An exfoliated or intercalated nanocomposites can be formed only with a low-reactivity diamine and long enough diffusion time; this ensures polymerization was taken place within the clay gallery. On the other hand, a PI / clay blend is formed with insufficient diffusion time and high diamine reactivity. Under this circumstance, nearly all monomers were captured outside the clay gallery and a homo-polyimide was formed independent of clay. These results were consistent with observations from TGA. The maximum degradation temperature (Td) of the nanocomposite increased with increasing diffusion time; Td of the nanocomposites with low-reactivity 1,3-phenylenediamine was 30oC greater than the nanocomposites with high-reactivity 4,4¡¦-oxydianiline.

Abstract Organically modified montmorillonite by a long chain alkylammonium surfactant was used to prepare polyimide/clay nanocomposites in this study. Several attempts were made in an effort to achieve fully exfoliated nanocomposites. These included the one-step method, two-step method and in-situ polymerization method. At the same time, the effects of polyimide structures and clay contents were studied. Two dianhydrides and two diamines were used to prepare polyimide/clay nanocomposites via the two-step method. The polyimide/clay nanocomposites with various clay contents from 1.5 ~ 10 wt % were prepared via the two-step method too. The structure of polyimides and the dispersion level of clay were identified by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). Thermogravimetric analysis (TGA) was performed to demonstrate the thermal stability of the nanocomposites. TGA and XRD results indicate the surfactants are intercalated into the layers of clay. FTIR results indicate the all polyimides in the nanocomposites are formed successfully. XRD results indicate the BPDA-ODA/clay nanocomposite within 3 % by weight of clay via the two-step method is shown to have the best dispersion level of clay. These results are consistent with observations from TGA. The temperature at 10 % by weight loss of the nanocomposite is 31 ¢J greater than that of pure BPDA-ODA. The formation mechanism of polyimide/clay nanocomposites via the two-step method can be described by three distinct steps. A polyamic acid/clay mixture with an exfoliated morphology is first formed. A portion of solvents and intercalated surfactants are then either degraded or expelled from the clay gallery under thermal imidization, resulting in a reduced gallery height of 1.32 nm. On the other hand, portion of the clay layers show an exfoliated morphology due to the effective surfactant and polyimide molecules. As a result, a partially exfoliated polyimide/clay nanocomposite is obtained.

Abstract A series of polyimide/silica hybrid composites have been synthesized by simultaneous polycondensation of the organic polyimide (PI) phase and the sol-gel reactions (hydrolysis and condensation) of the inorganic silica phase. Sol-gel parameters such as pH value, solvent, water/Si ratio, were systematically varied so that their effect on the microstructure of silica could be explored. Emphasis has been placed on the interactions between the organic and the inorganic phases by FTIR with the introduction of two coupling agents, i.e., g-glycidyloxypropyl- trimethoxysilane (GOPTMS) and 3-amino-propyltriethoxysilane (ATPES). Thermal and electrical properties of the hybrid composites were examined by TGA, DSC, and AC impedance and the morphology by SEM; these properties were correlated to their synthesis chemistry. FTIR results indicate complete imidization of PI, not affected by the presence of the catalyst, solvent ethanol, and silica particles of the inorganic phase. The hybrid films with lower silica content give higher transparency. TGA results indicate ~ 25 ¢Jincrease of decomposition temperature for the hybrid composites compared to the neat PI; it shows a minimum when pH = 4. The thermal stability of the APTES system is generally better than the GOPTMS system. SEM results indicate that maximum particle size is obtained for the system with pH = 4. AC impedance results indicate that dielectric constant increases with the silica particle size and the silica content. The coupling agents help to reduce the silica particle size (~ 100 nm for GOPTMS, ~ 200 nm for ATPES, and > 400 nm with no coupling agent) and to distribute evenly the silica particles in the PI matrix.