| In order to satisfy the requirements of the electronic products to the development of smaller, thinner, lighter, higher reliability direction, high density interconnect printed circuit boards have been developed rapidly since the1990s. It represents the developing direction of current printed circuit boards, since it introduces blind or buried via in conventional printed circuit boards and can produce a thin, multi-layer, stable, high density interconnect printed circuit boards.High density interconnect printed circuit boards are usually manufactured by the method of building-up, which uses a double or four-layers key core as the base, and then build-up conductive and insulating layer as outer layers in order to ultimately achieve multilayer structure. The inner layer circuit is connected by common via and plating through holes, and the production of via has been one of the core problems in high density interconnect printed circuit boards. Typically, the production methods of micro via include:laser drilling, light-induced etching and plasma etching. More than90%of micro blind holes on the circuit boards are made by CO2laser drilling so far, which open a window by chemical etching first, then the resin is removed after it is ablated by the heat from the infrared wavelength of CO2laser, thus the micro via is formed. It is the most commonly-used means of producing blind and buried via because of its high precision, stable process and mature technology, however, the large investment in equipment of laser drilling and the low efficiency are the most serious problems. In this paper, a polymer has been studied, which not only can light-induced imaging, but also can become a permanent insulating material to form circuit board inner layer. This paper is divided into two parts:(1)2-diazo-l-naphthoquinone-5-sulfonyl chloride (hereinafter abbreviated as2,1,5-sulfonyl chloride) and the phenolic resin for presensitized plate were used as raw materials to built up, and the formulation, the methods of exposure and development were explored. The optimum conditions were studied by the influence factors such as solid content, ratio of photosensitive agent and resin, exposure time. The optimum reaction conditions were:the solid content was20%; the ratio of photosensitive agent and resin was1:3; the exposure time was8min.(2) The photosensitive epoxy resin was synthesized from E-44epoxy resin and2,1,5-sulfonyl chloride as raw materials by esterification reaction, then the structure of target product was characterized by FT-IR. Different types of curing agents were chosen to uniformly mix with synthetic product, then the mixtures were coated on the copper clad laminate until resin film was formed, finally the resin in exposed areas was selectively removed by alkali lye after it was selectively exposed by UV exposure machine. The thickness of the resin film was tested after curing and the cured product was detected by thermal analysis. The optimum reaction conditions were studied by the effect of solvents, temperature, time, molar ratio of reactants on the yields. The optimum reaction conditions were:the solvent was1,2-dichloroethane; the reaction temperature was50℃for5h, the ratio of E-44epoxy resin:2,1,5-sulfonyl chloride: triethylamine was1:2.2:2.6(molar ratio). The optimum conditions were studied by the effect of different curing agents, exposure intensity, developing conditions on the developing efficiency. The optimum reaction conditions were:the curing agent was phenolic resin2123; the amount of curing agent was5%; exposure energy was400mJ/cm2; developing condition was2%NaOH mixed solution (deionized water: ethanol:acetone=9:0.5:0.5). The average thickness of the resin film was δ=15.6μm and the decomposition temperature was about226℃. |
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