Preparation And Properties Of Polyimide Films With Low Dielectric Constant

With the rapid development of today’s society and the entry of the information age,people’s requirements for information transmission speed continue to increase.5G communication has gradually been integrated into people’s production and life,which requires various intelligent devices to be more inclined towards low dielectric and low energy consumption,Therefore,advanced electronic sealing technology came into being,and polyimide（PI）was widely used as interlayer dielectric material due to its excellent performance.The dielectric constant of traditional polyimide is about 3.2～4.0.80%of China’s high-performance polyimide films depend on imports and are increasingly limited in today’s environment,Therefore,it is urgent to further reduce the dielectric constant of polyimide and improve its various properties.This article aims to conduct research work around reducing dielectric constant,reducing dielectric loss,and balancing various performance.The main content of this paper includes the following three parts.（1）Twelve polyimides with different structures were constructed by simulation,The polyimides with different structures in the highest energy occupying molecular orbital E_HOMO,Energy of lowest unoccupied molecular orbital E_LUMO、The energy difference between the highest occupied molecule and the lowest unoccupied molecular orbitalΔE_{（HOMO-LUMO）}、The maximum net negative charge of atoms in a molecule q^-、Solubility parametersδ、Free Volume FFV,End Distance/Free Volume（EED/FFV）and other aspects have explored the impact on dielectric properties,laying the foundation for the next step of conducting experiments.Through theoretical simulation,the dielectric constant of polyimide was reduced from 3.7 to 2.7,and the introduction of tert butyl greatly improved the dielectric property of polyimide,which provided a basis for the next experiment and confirmed the feasibility of introducing tert butyl to reduce the dielectric constant.（2）Preparation and properties of traditional pyromellitic anhydride polyimide films.The polyimide film was prepared by the reaction of 4.4’-diaminodiphenyl ether（ODA）and pyromellitic anhydride（PMDA）with traditional methods,In the experiment,the best reaction process（preparation method,solvent selection,reaction temperature,etc.）for preparing polyimide film was explored,and the thermal,mechanical and dielectric properties of the film were measured,The experiment shows that the traditional pyromellitic anhydride type polyimide film prepared has good dielectric and thermodynamic properties,and the film prepared is uniform with dielectric constant between 3.6 and 3.9,which provides an experimental basis for the next step of introducing tert butyl into the monomer to synthesize polyimide.（3）Preparation and properties of tert butyl pyromellitic anhydride polyimide films.Through simulation,it can be concluded that the introduction of tert butyl can effectively reduce the dielectric constant.Therefore,this chapter combines the actual synthesis of diamine monomers containing tert butyl,and conducts polymerization reactions with four types of anhydrides（phthalic anhydride（PMDA）,3,3’,4,4’-biphenylenetetracarboxylic anhydride（BPDA）,4,4’-biphenyl ether dianhydride（ODPA）,3,3’,4,4’-benzophenone tetracarboxylic anhydride（BTDA））according to the optimal experimental conditions obtained above.Measure the heat resistance,mechanical properties,dielectric properties,etc.of the new type of thin film prepared.The experimental results show that the four new polyimide films have good heat resistance,mechanical properties and dielectric properties,and the dielectric constant is about 3.0,which is basically consistent with the simulation results.