Research On Grafting Technology And Metallization On Organic Substrate

Metalized organic polymer materials were widely used in all aspects of production because of its excellent performance such as electrical conductivity, thermal conductivity and easy formability. However, the bonding strength between organic polymer materials and surface metal layer was weak. Study on the pretreatment and metallization technology of organic polymer materials was the key to obtain excellent surface metal layer. Flexible polyimide(PI) film and rigid polyphenylene ether(PPE) board were selected as substrate materials. Basic research work on the surface modification and surface metallization of two kinds of organic substrates were carried out. The main research contents of this paper were as follows:Alkali A solution was used to the pretreatment of PI film. The changes of surface roughness, infiltration and functional groups of PI film before and after pretreatment had been studied. The results showed that the surface roughness of PI film was increased and the infiltration of the film was improved. The structure of the imides ring was opened due to the hydrolysis reaction. Sodium thiosulfate, potassium thiocyanate and thiourea were chosen as the grafting monomers of PI film. Infrared spectrum analysis showed that monomers could form chemical bonding on the surface of PI film, and the grafting modification of PI film could be realized. The grafting degree with increasing monomer concentration, grafting time and grafting temperature were studied when sodium thiosulfate chosen as the monomer. After optimization, the grafting concentration was 5 g/L, grafting time was 12 min and grafting temperature was 60°C.The pretreatment of PPE board had been studied. Methyl group on the benzene ring of the PPE board was oxidized to carboxyl after the oxidant M pretreatment. Polar groups of the surface increased and contact angle with water reduced through surface pretreatment. APTES and MPTES mixed coupling agent was carried out to modify PPE board. After grafting modification, the stretching vibration peak intensity of S-H, N-H and Si-O-H were slightly increased. PPE board was grafted by silane coupling agent successfully. The research of cure time and temperature showed that the proper time was 15 min and the temperature was 50°C for the grafting of PPE board.Electroless copper plating method was used to realize the surface metallization of PI film and PPE board. The morphology, composition and crystal structure of the metal layer were analyzed by SEM, EDS and XRD. The analysis showed that the metal layer was uniform and compact, with good coverage, less impurity and well crystallized. In addition, the electrical conductivity, thermal stability of the metalized substrates and the bonding properties between the metal layer and the substrates were studied. The results showed that the metalized PI film and PPE board had good electrical conductivity and thermal stability. Binding force test indicated that the average peel strength between metal layer and PI film was up to 6.0 N/cm, and the combination with PPE board was up to 5B standard.