Preparation And Properties Of Polyimide Paper-based Composites For Copper Clad Laminate

Printed Circuit Board is used in almost all electronic products,from high-end electronic products for aerospace electronics to common household appliances.Due to the development of the electronic information industry in the direction of high frequency and high speed,this forces printed circuit board must have many high quality characteristics,copper clad laminate as its core substrate,also need to have a variety of high quality and high technology characteristics.The advantages and disadvantages of dielectric properties,thermal properties,mechanical properties and other properties of copper clad laminate are important indicators to measure their application value.Good dielectric properties are helpful to reduce the high frequency and high speed signal transmission fluctuation and loss.Good thermal stability determines the use of copper clad laminate.It is essential for copper clad laminate to maintain size stability at a certain temperature for its wider application.Good mechanical properties can ensure that it is subjected to external forces and not easy to bend deformation.The traditional paper-based copper clad laminate has poor mechanical strength,poor thermal stability and unstable dielectric properties.The overall performance of the substrate can be improved by using high performance fiber paper.As an inorganic high-performance filler with low thermal expansion,good dielectric properties,low water absorption and wear resistance,silicon micro powder can be added to paper-based copper clad laminate to improve the performance and reduce the production cost,but the specific effect on the performance of copper clad laminate and the enhancement mechanism need to be further investigated.The research in this article is summarized below:Firstly,polyimide fiber paper was prepared by wet nonwoven technology using polyimide（PI）short-cut fiber and para-aramid（PPTA）pulp as raw materials to investigate the influence of different raw material ratios on the mechanical properties of the paper and to study the mechanical properties of PI fiber paper at different types and amounts of additives.The results show that:When PI cut fiber with length of 6 mm,size of 1.67 D and PPTA pulp with beating degree of 25.3°SR are used as raw materials,and the ratio of the two is 3:7,and the dispersive agent of polyvinyl oxide A1 is 0.06%and the dry strength agent of cationic polyacrylamide is 0.6%,PI fiber base paper tensile index is 34.56 N·m/g,tear index is 37.42m N·m²/g,tightness is 0.39 g/cm³.Secondly,in order to further determine the preparation process of copper clad laminate,the curing kinetics of PI resin for copper clad laminates were explored by using differential scanning calorimetry and the curing temperature profiles of PI resin at different heating rates were analyzed.The optimal curing temperature of the PI resin system was obtained by linear fitting to determine the temperature parameters in the preparation process of copper clad laminate.After that,the hot pressing pressure and hot pressing time were determined by hot pressing orthogonal experiments,and finally the optimal laminating process for PI paper-based copper clad laminates was obtained.The first stage was 89℃/30 min/10 MPa.The second stage was 131℃/60 min/15 MPa.The third stage was 166℃/30 min/15 MPa.Copper clad laminate with different reinforcement materials were prepared and tested under the same preparation process conditions.Finally,the dielectric constant（Dk）was 2.7,the dielectric loss（Df）was 0.003,the thermal decomposition temperature(T_d-5%)was 482℃,the coefficient of thermal expansion（CTE）was 4.73μm/（m·℃）,and the peel strength was 0.9 N/mm.Among them,the dielectric properties,thermal decomposition temperature and peel strength of PI paper-based copper clad laminate can meet the quality standards,but its coefficient of thermal expansion needs to be further improved.Based on the above conclusions,in order to further improve the coefficient of thermal expansion and mechanical properties of PI paper-based copper clad laminate,PDA@Si O₂/PI paper-based copper clad laminate was prepared by using polydopamine（PDA）modified silicon micropowder.The results show that the surface of silicon micropowder is coated with a thin layer of PDA coating by modification,which has more active groups on the surface.The dispersibility was improved while it was beneficial to improve the mechanical properties of PI filled fiber paper.When the filling amount is 30%,the Dk of PDA@Si O₂/PI paper-based copper clad laminate is 3.37,and Df is 0.0048,and T_d-5%is 343℃,and CTE is 2.98μm/（m·℃）,and bending strength is 253 MPa,and peeling strength is 1.13 N/mm.It has the advantages of excellent mechanical properties,dielectric properties,thermal stability and dimensional stability,and has a good application prospect.