Selectively Metalization Of Nickel And Micropattern Construction On Polymer Surfaces

The rapid development of advanced science and technology is closely related to theconstruction of fine microstructures. And the construction of micro-patterns ontomaterial surfaces has great potential of development and broad prospect ofapplications in many fields such as integrated circuits, micro-electro-mechanicalsystems, biochips and tissue engineering. As flexible substrates, polymer materialsare equipped with excellent performances，low cost, light weight and could be easilyprocessed. Now polymer materials have been widely concerned in micro-circuitsubstrate applications. However, the inertness of polymer surfaces makes it becomesa difficult problem to increase the binding force between the substrate surfaces andmetal. Furthermore, the strength of interfacial bonding directly influences theperformance and service life of the products. Generally, in the traditionalmicroelectronic processing, people enhanced interfacial mechanical binding byincreasing the surface roughness of substrates, thus increasing the adhesion. However,it would make the preparation of micro-circuits more difficult. Moreover, it putsforward higher requirements for the selectivity of metal deposition on the surface torealize the refinement of surface patterns. Therefore, it is of great importance to find anovel and effect surface modification and micro-processing technology, in order torealize the miniaturization and refinement of micro-patterns construction ontosubstrate surfaces, improve the fidelity of micro-patterns, enhance the interfacialbinding force and the selectivity of metal deposition at the same time.This paper selects the polymer material PET as substrates. At first, the UVradiation technology is used for surface modification on PET substrates, thusintroducing hydrophilic groups. Then APTES monolayers are self-assembled onto thesubstrate surfaces, providing the substrate surfaces with amino groups. And UVlithography is used to regionally adjust the property of surfaces through photomasks.Finally, selective deposition of nickel on surface modified PET substrates is carriedout through electroless nickel plating technology, thus constructing nickelmicro-patterns. The specific contents are as follows:1. The inert nature of PET substrates are successfully activated through UVradiation technology, introducing reactive hydrophilic groups onto surfaces, so as to realize the self-assembly of PET surfaces. It provides the surfaces with amino groupsand lays a foundation for increasing the adhesion between substrate surfaces andnickel layer. Static water contact angle tests show: after ultraviolet irradiation, thehydrophilic property of PET substrate surfaces enhanced; After self-assembly ofAPTES monolayers, the water contact angle of surfaces rise.The results of colorreaction of ninhydrine and XPS tests show that the self-assembly of APTESmonolayers on PET substrates is successfully realized.2. Nickel layers obtained from the optimized formula and processingparameters have the best glossness and the highest adhesion. Moreover, the stabilityof bath solution is good and the deposition rate of nickel is high. The optimumformula of plating solution and processing parameters of electroless nickel platingwith the control variate method: hexahydrate (nickel sulfate)20g/L, sodiumhypophosphite (reducing agent)140g/L, sodium citrate (complexing agent)10g/L,ammonia (pH regulator)30mL/L; bath temperature is50°C, and plating time is5.5min.3. The accurate control of selective nickel deposition onto PET surfaces issuccessfully realized through the VUV etching technique, and nickel micro-patternsare successfully constructed onto the PET substrates. The results of opticalmicroscope and SEM tests show: the lines and boundaries in nickel micro-patterns areclear and the micro-patterns are provided with good brightness, high resolution andgood fidelity; nickel particles within the nickel deposition regions are of uniformsizes; and the average diameter of the particles is approximately20nm.Through the methods and technologies in this paper, nickel micro-patterns can besuccessfully constructed on polymer PET substrates. And the micro-patterns areequipped with excellent comprehensive performances. It makes the design andprocessing of micro-circuits and biological sensors become possible. Furthermore, itlays a foundation for the rapid development of integrated circuits,micro-electro-mechanical systems, biochips, tissue engineering and other fields.