Study On Electroless Copper Plating Technology Of SiO₂ Filled Epoxy Resin/PET Substrate

Ultra-thin stack packaging and flexible electronic interconnection technologies are based on fan out wafer level packaging which can meet the needs of consumer electronic products for thinness and miniaturization and have important application prospects in the field of intelligent electronic systems.Surface metallization of polymer materials for packaging is one of the key technologies for ultra-thin Po P packaging and flexible electronic interconnection to realize the subsequent interconnected circuit preparation,which has received extensive attention in the industry.The research hotspots include the electrical properties of the metallization layer and the adhesion between the coating and the substrate.Based on actual needs,this paper studies the deposition technology of electroless copper plating on the surfaces of SiO₂ filled epoxy resin substrate and PET substrate.SiO₂ filled epoxy resin substrate is an organic-inorganic composite material.The difference in surface morphology directly affects the adhesion between the electroless copper plating layer and the substrate.Surface treatment modification is the mainstream technology in the industry.In this experiment,the chemical micro-etching technology was used to discuss the change rule between the surface modification parameters of SiO₂filled epoxy resin substrate and the interface bonding force of the deposited copper layer.At the same time,by optimizing heat treatment process of modified substrate,wettability test of surface topography and roughness study,the optimal surface treatment parameters of SiO₂ filled epoxy resin substrate were optimized and the failure mechanism of copper plating layer and epoxy resin substrate was proposed,which established a theoretical basis for the application of chemical micro-etching technology in IC through-hole plastic sealing technology.The results indicate that a special ball-gap socket structure is formed on the surface when the surface treatment time is 15 min,which can significantly improve the adhesion of the interface.After electroless copper plating to achieve surface metallization,the substrate is thickened by electroplating and post-pattern production.Different plating layers are combined to form anti-stripping patterns and the anti-stripping patterns before and after heat treatment are subjected to anti-stripping tests.The test results show that heat treatment can increase the adhesion of 0.19 N/mm to 0.47 N/mm.Meanwhile,the interface failure mode change from cohesive failure and interface failure to pure cohesive failure.This technology is used to make the metal seed layer in the plastic-sealed through hole,the seed layer and the epoxy molding compound are well combined after 10 times of reflow soldering.To realize electroless copper plating on the surface of PET substrate,the substrate surface activation technology is one of the key technologies to obtain a good coating.In this work,the PET surface was grafted and modified by formulating palladium-based modified ink and catalyzed the deposition of copper after plasma activation treatment.The effects of air plasma treatment on the roughness,wettability and surface chemical state of the modified layer,as well as the electrical conductivity,fatigue resistance and interfacial bonding properties of the coating after chemical copper plating were investigated.The study find that the plasma treatment process not only reduce the Pd²⁺in the modified layer to metal palladium with catalytic properties and improved the wettability of the interface,but the network nanostructure generate on the surface increased the roughness of the interface,thereby improving the interface bonding.force.After 1 h of plating treatment,the resistivity of the deposited copper layer was 2.26×10^-6?·cm,and the interface bonding force between the copper plating layer and the PET substrate was 5 B.