Analysis To Oil Bleeds Of Elastomeric Thermal Silicone Conductive Pads

Oil bleed phenomenon is a serious problem of elastomeric thermal silicone conductive pads applied in electronic and electric industry.Oils bleed out from the elastomeric thermal silicone conductive pads,and cause the device surfaces to be contaminated.Because the oil bleeds can adhere the substances in the surrounding area.This affects the conductive ability of the devices and even causes many other serious problems.It is necessary for us to explore the components of bleeding oils and the effect of chemical parameters on oil bleeds in order if we want to solve this problem.Elastomeric thermal silicone conductive pads are generally prepared by two mixed parts.One is elastomeric silicone rubber,and the other is fillers which support effective thermal conductive property.In this paper,we mainly identified the components of bleeding oils and investigated the effect of chemical parameters of silicones on oil bleeds.We designed a simple silicone matrix model system,which included vinyl silicone,hydrosilicone,catalyst and inhibitor.We did not add inorganic fillers in this model system in order to simplify the oil bleeds.The components of bleeding oils from these vinyl silicone/hydrosilicone systems were analyzed by GPC and 1H NMR in order to identify the chemical components of the oils and infer the mechanism and process of oil bleeding.Four kinds of vinyl silicones and three kinds of hydrosilicones were involved in the article.The effect of silicones on density,crosslinking density and hardness of elastomeric thermal silicone pads were investigated firstly.The major contents of this research were to tesify the components of bleeding oils and explore the effect of chemical parameters of silicones on oil bleeds.The results demonstrated that the main components of oil bleeds were the uncrosslinked silicones in the cured resins,such as unreacted silicone materials,impurities without functional groups in original materials and macromolecular substances produced by the hydrosilylation reaction.In addition,high crosslinking density and high number-average molecular weight of residue vinyl silicones in cured resin benefited for low amount of oil bleeds.Meanwhile,low Si-H content of hydrosilicone at a certain degree could also reduce the amount of oil bleeds.In conclusion,the results in the research is helpful for us to know the oil bleed phenomenon and perfect the production of elastomeric thermal silicone conductive pads.