Synthesis And Properties Of 3,6-Bisiliconyl Substituted Benzocyclobutene And Their Polymers

With the rapid and vigorous development of 5G technology,the requirements for electronic devices are becoming more and more stringent.The research on low dielectric materials used in electronic interlayer media has also attracted the attention of researchers and scholars.Benzocyclobutene（BCB）has a unique molecular structure.Under the condition of heating,the four-membered ring can open to form active intermediates,and continue to react with the same intermediates or monomers containing unsaturated bonds to form a dense network of cured crosslinking,and the whole process does not need to add catalyst,there will be no small molecule release affect the processing technology and properties of resin.It has a symmetric structure,low molecular polarizability,and good film forming,water resistance and dielectric properties,which causes many scholars to join the study of BCB.Based on this,a series of 3,6-bissilyl substituted benzocyclobutene compounds were designed and synthesized in this paper.Their mostly contain Si-C bonds,C-C bonds and SiO-Si bonds with low polarity.Moreover,the 3,6-site substituted monomers have structural symmetry and lower overall molecular polarizability,which can effectively reduce the dielectric constant and dielectric loss of materials.The presence of benzene ring also provides a certain rigidity and mechanical properties for the resin.The monomer structure contains many BCB groups and olefinic bonds.Under the heating condition,multiple active thermal crosslinking sites occur cross-linking,which prevents molecular accumulation and distortion polarization to a certain extent,and further improves the dielectric and mechanical properties of the resin.In addition,in the synthesis of 3,6-bis-substituted benzocyclobutene substrates,we simplified the synthesis steps and adopted Birch reduction and oxidation reaction to directly obtain the target product in two steps,eliminating the long,complex and risky operation,saving costs and improving efficiency.1.The experimental process of synthesis of 3,6-bis（dimethylsilyl）benzocyclobutene（3,6-D（DMHS）BCB）by two-step method was introduced.Then,3,6-bis[（4-benzocyclobutene）ethylsilyl]benzocyclobutene（M1）was prepared by silohydroaddition reaction of 4-vinyl benzocyclobutene（4-VBCB）.At the same time,1,4-bis（dimethylsiliconyl）benzene（1,4-D（DMHS）B）was reacted with 4-VBCB to prepare 1,4-bis[（4-benzocyclobutenyl）ethylsiliconyl]benzene monomer（M2）.By contrast,how crosslinking density affects the properties of the resin was investigated.2.1-[（4-benzocyclobutenyl）vinyl]-1’-vinyl tetrameryldisiloxane（DVS-BCB）was synthesized by Heck reaction,and 3,6-D（DMHS）BCB monomer synthesized by 1,4-D（DMHS）B and two-step method was reacted with it respectively.3,6-bis[1-（4-benzocyclobutenyl）vinyl-1’-ethylsilyl] benzocyclobutene（M3）and 1,4-bis[1-（4-benzocyclobutenyl）vinyl-1’-ethylsilyl] benzene（M4）were obtained.These monomers contain both BCB groups and unsaturated double bonds,and have more active thermal crosslinking sites.The influence of crosslinking density on resin properties was further studied.3.3,6-bis（dimethylallylsilyl）benzocyclobutene（3,6-D（DMAS）BCB）monomer was successfully prepared by the reaction of dimethylallylchlorosilane with BCB in a two-step process,with a yield of 78%.On this basis,it reacted with 4-bromobenzocyclobutene（4-Br BCb）to form 3,6-bis [（4-benzocyclobutene）vinyl methylsilyl] benzocyclobutene monomer（M5）.The structure and properties of the resin were compared with those of DVSBCB resin with better comprehensive properties.To sum up,this paper provides a two-step method for the synthesis of bisiliconyl substituted benzocyclobutene compounds,and a series of monomers with symmetric structure are designed and synthesized,which have relatively excellent performance and have potential application value in the microelectronics industry and related fields.