Abstract
This study selected 3 types of epoxy resin, including cresol novolac (E1), phenol novolac epoxy resin (E2),and bisphenol A (E3). Utlizing the glycidyl group of the epoxy resin, we synthesized resins with carboxyl acid and photoreactive functional group(E1-2,E2-2,E3-2). In order to enhance the photosensitive character, part of the carboxyl groups were reacted with GMA (Glycidyl Methacrylate) to obtain E1-3,E2-3,E3-3. Thus there are six synthetic resins and their structures were identified E3-3 by nuclear magnetic resonance spectroscopy (1H-NMR) and infrared spectroscopy (IR). photoresists were formulated with above synthetic resins, photoinitiator and photoreactive monomer and their exposure properties were also tested. It was found that E1-3,E2-3,and E3-3 exhibit better sensitivity than E1-2,E2-2,E3-2, while is the best. For PCB application, they all passed solder test,while E1-3 and E2-3 had better sensitivity than the corresponding commercial product.Methyl methacrylate, methacrylic acid, styrene and 2-hydroethyl methacrylate were used to synthesize a prepolymer with carboxylic acid group through free-radical polymerization(PMMSH). Glycidyl methacrylate was then added to react with carboxylic acid groups of PMMSH to form photosensitive copolymer PMMSHgG. Nuclear magnetic resonance and infrared were used to confirm the structures and functional group of the prepolymer and the copolymer while GPC was employed to determine the molecular weight. The sensitivity and resolution of the copolymers were obtained through characteristic exposure curve and SEM observation, respectively. PMMSHgG was also mixed with dry-peelable plastisol, acrylic acid monomer, and photoinitiator to form a photo-imageable dry-peelable plastisol. A suitable peelable composition without scum after UV exposure and post-baking was identified.Dianhydride monomer, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), and two diamine monomers, 4,4’-diamino-3,3’-biphenyldiol (HAB) and 2,4-diaminophenol dihydrochloride (DAP), were used to synthesize a series of poly(hydroxyl amic acid). Further functionalization by grafting acrylate groups yields the corresponding poly(acrylate amic acid) which could be used as a negative-tone photosensitive polyimide. The analysis of chemical composition and molecular weight of these poly(amic acid) determined by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy and gel permeation chromatography (GPC), respectively. It revealed that the molecular weight of the poly(hydrxoyl amic acid) increased with the molar content of HAB in the feedstock, because HAB exhibited higher polymerization reactivity than DAP. Moreover, the degree of grafting acrylate groups onto poly(hydroxyl amic acid) was determined by 1H-NMR spectroscopy. Photoresist was formulated by adding 2-benzyl-2-N,N- dimethylamino-1-(4-morpholinophenyl) butanone (IRG369) and isopropylthioxanthone (ITX) as photoinitiator, tetra(ethylene glycol) diacrylate (TEGDA) as a crosslinker and tribromomethyl phenyl sulfone (TBPS) as a photosensitizer. The photosensitive polyimide precursor exhibited a photosensitivity of 200mJ/cm2 and a contrast of 1.78. A pattern with a resolution of 10μm was observed in an optical micrograph after thermal imidization at 300oC.