Research On The Bonding Effect Of Copper Circuit And Liquid Crystal Polymer Lamination Of High Frequency Flexible Printed Circuit

With the growing development of high-frequency flexible printed circuits,the liquid crystal polymer material has caused significant concerns in the industry and academic properties due to its superior dielectric properties.However,due to their stable physical and chemical performance with the metal combinations.The problem of poor peel strength limits its application.Further developing performance of excellent highfrequency flexible electronic devices challenged.This thesis developed a new process in the field of flexible printed copper circuits and liquid crystal polymer lamination.This developed process can effectively reduce product thickness compared to current methods in industry and can reduce lamination temperature compared to previous studies.In this thesis,the peel strength test results of the final multi-layer board samples after different plasma treatment processes and copper surface oxidation and surface coating silane processes were tested by a peel strength tester,and the effect of different process conditions on the peel strength of the final samples was explored.The optimal manufacturing process conditions are determined as follows: the optimal plasma processing power is 6 k W,the processing time is 30 min,and the gas used in the processing is 100% pure oxygen.The optimal processing conditions for immersion in the solution for oxidation are: the solution temperature was 100 °C and the treatment time was 120 s.In this thesis,scanning electron microscopy and 3D laser co-polymerization microscopy were used to explore the surface morphology characteristics of liquid crystal polymers and copper under different treatment conditions.The effect of oxygen plasma treatment on the surface of the liquid crystal polymer is to improve the hydrophilicity of the surface.The main result of copper surface oxidation is cuprous oxide,which provides conditions for the combination of silanes.This study also explored the lamination process conditions in the high-temperature hot pressing process,and analyzed different lamination times,lamination temperatures,whether to pre-press,the type of protective film used,and whether to bake the finished product after lamination.The influence of the final flexible multilayer board on the peel strength of the sample,the optimal lamination conditions were determined as the lamination time of 300 s,the lamination temperature of 180 ℃,and the pre-pressing for10 s,and the high-temperature release film was used as the protective film for lamination..At the same time,in this thesis,the samples before and after the peel strength test were analyzed by scanning electron microscopy,and it was found that when the peel strength reached the maximum,the tear occurred inside the liquid crystal polymer,and the product reliability was good;It is found that the thickness of the copper surface oxide layer and the silane intermediate layer after lamination is about 100-200 nm.The process proposed in this thesis simplifies the process steps while ensuring the reliability of the peel strength of the product.The thickness of the final product has been improved,and the peel strength exceeds the standard for industrial applications.