近年来由于表面安装技术(SMT)的发展以及SMT用的小面积、高密度、薄层化多层板的不断涌现,对传统的热风整平(HOT Air Levelling)工艺提出了严竣的挑战。 为此,在国外一些厂家已推出水溶性耐热预焊剂替代热风整平工艺,如日本四国化成和美...近年来由于表面安装技术(SMT)的发展以及SMT用的小面积、高密度、薄层化多层板的不断涌现,对传统的热风整平(HOT Air Levelling)工艺提出了严竣的挑战。 为此,在国外一些厂家已推出水溶性耐热预焊剂替代热风整平工艺,如日本四国化成和美国chemcut公司的Cu—coat A和Schercoat。它们优于早期的松香型和烷基咪唑型预焊剂,具有在高温下承受三次钎焊的功能,因而在新的印制板组装焊接技术上展示出广阔的前景。 本文作者最近对新型水溶性耐热预焊剂这一课题进行了探索,研制了以烷基苯并咪唑(Al-Kylbenzimidazole)为基的预焊剂,其护铜、耐热、可焊性能优良,对PCB行业生产和技术进步,具有良好的前景。展开更多
To date, few reports have been concerned with the physical properties of the liquid phases of imidazoles and benzimidazoles- potential starting materials for a great number of ionic liquids. Prior research has indicat...To date, few reports have been concerned with the physical properties of the liquid phases of imidazoles and benzimidazoles- potential starting materials for a great number of ionic liquids. Prior research has indicated that alkylimidazole solvents exhibit different, and potentially advantageous physical properties, when compared to corresponding imidazolium-based ionic liquids. Given that even the most fundamental physical properties of alkylimidazole solvents have only recently been reported, there is still a lack of data for other relevant imidazole derivatives, including benzimidazoles. In this work, we have synthesized a se- ries of eight 1-n-alkylbenzimidazoles, with chain lengths ranging from ethyl to dodecyl, all of which exist as neat liquids at ambient temperature. Their densities and viscosities have been determined as functions of both temperature and molecular weight. Alkylbenzimidazoles have been found to exhibit viscosities that are more similar to imidazolium-based ILs than al- kylimidazoles, owed to a large contribution to viscosity from the presence of a fused ring system. Solubilities of CO2 and SO2, two species of concern in the emission of coal-fired power generation, were determined for selected alkylbenzimidazoles to understand what effects a fused ring system might have on gas solubility. For both gases, alkylbenzimidazoles were deter- mined to experience physical, non-chemically reactive, interactions. The solubility of CO2 in alkylbenzimidazoles is 10%-30% less than observed for corresponding ILs and alkylimidazoles. 1-butylbenzimidazole was found to readily absorb at least 0.333 gram SO2 per gram at low pressure and ambient temperature, which could be readily desorbed under an N： flush, a behavior more similar to imidazolium-based ILs than alkylimidazoles. Thus, we find that as solvents for gas separations, benzimidazoles share characteristics with both ILs and alkylimidazoles.展开更多
基金supported by ION Engineering, LLCUnited States Department of Energy-National Energy Technology Laboratory(DE-FE00005799)the National Science Foundation Research Experiences for Undergraduates Program (EEC-1062705)
文摘To date, few reports have been concerned with the physical properties of the liquid phases of imidazoles and benzimidazoles- potential starting materials for a great number of ionic liquids. Prior research has indicated that alkylimidazole solvents exhibit different, and potentially advantageous physical properties, when compared to corresponding imidazolium-based ionic liquids. Given that even the most fundamental physical properties of alkylimidazole solvents have only recently been reported, there is still a lack of data for other relevant imidazole derivatives, including benzimidazoles. In this work, we have synthesized a se- ries of eight 1-n-alkylbenzimidazoles, with chain lengths ranging from ethyl to dodecyl, all of which exist as neat liquids at ambient temperature. Their densities and viscosities have been determined as functions of both temperature and molecular weight. Alkylbenzimidazoles have been found to exhibit viscosities that are more similar to imidazolium-based ILs than al- kylimidazoles, owed to a large contribution to viscosity from the presence of a fused ring system. Solubilities of CO2 and SO2, two species of concern in the emission of coal-fired power generation, were determined for selected alkylbenzimidazoles to understand what effects a fused ring system might have on gas solubility. For both gases, alkylbenzimidazoles were deter- mined to experience physical, non-chemically reactive, interactions. The solubility of CO2 in alkylbenzimidazoles is 10%-30% less than observed for corresponding ILs and alkylimidazoles. 1-butylbenzimidazole was found to readily absorb at least 0.333 gram SO2 per gram at low pressure and ambient temperature, which could be readily desorbed under an N： flush, a behavior more similar to imidazolium-based ILs than alkylimidazoles. Thus, we find that as solvents for gas separations, benzimidazoles share characteristics with both ILs and alkylimidazoles.
