The systematic search and design of phosphine ligands (PR(3)) and amine cocatalysts resulted in obtaining pentamethyl-cyclopentadienyl (Cp*) ruthenium(II) phosphine complexes [RuCp*Cl(PR(3))(2)], which are highly active and removable catalysts, for transition-metal-catalyzed living radical polymerization of methyl methacrylate (MMA). The catalysts are conveniently prepared in situ from a tetrameric precursor [RuCp*(mu(3)-Cl)](4) and a selected phosphine (PR(3)). The combination of the meta-tolyl phosphine [P(m-Tol)(3)] ligand and a primary diamine cocatalyst [NH(2)(CH(2))(6)NH(2)] provides a highly active catalytic system with precision control of the molecular weight of the polymer. The high activity enables a low catalyst dose and a high turn-over frequency without deteriorating the controllability. A hydrophilic amine cocatalyst (amino alcohol) in place of the diamine, further forms an active and removable catalyst; simple treatment with acidic water gave colorless polymers visually free from metal residues (>97 % removal; <64 ppm).
We found that positive-tone photosensitive polyimide (posi-PSPI) shows not to be compatible for electroless Ni/Au plating process which are used for Au micro bumping. In order to meet compatibility for the process, we improved chemical resistance of positive-tone photosensitive polyimide especially for electroless plating process. Changing of polyimide polymer structure is most effective to obtain chemical resistant for the electroless plating process. The obtained PSPI are useful for saving bumping process and reliable in forming pattern.
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