Size And Property Control Of Laser Micro-cladding Electronic Pastes On Organic Polymer Substrates

Direct writing technology is an intelligent manufacturing technology which is maskless,high-flexibility,raw material-saving,and with wide application range of substrates.It is of great significance in sample manufacturing,small batch manufacturing,and medium-scale production.In this thesis,basing on the technologies of micropen direct writing and laser micro-cladding of traditional thick-film electronic paste,conductive and resistive material layers were fabricated on heat-sensitive epoxy fiberglass substrates,respectively.In addition,a polyimide?PI?dielectric layer was fabricated on aluminum alloy substrate,and conductive patterns were fabricated on the surface of the PI layer.The effects of processing parameters of the micropen and laser on the sizes and properties of these additive material layers were investigated in detail.First,the effect of the processing parameters of micropen direct writing on the direct-writing line size was explored.Through orthogonal experiment,it was found that the diameter of micropen tip and direct-writing velocity were the main factors of affecting the line width and thickness.Basing on this,the effect of direct-writing overlapping on the direct-writing film thickness and surface roughness was exploited.It showed that the direct-writing film with high flatness could be obtained when the center distance between two lines was 60%-80%of the width of the single line.A PI precursor paste suitable for micropen direct writing was prepared,and the PI dielectric layer with a pattern area of 60 mm×60 mm and a thickness of more than 0.2 mm was prepared on the aluminum alloy substrate by multi-layer direct writing and on-line thermal treatment of intermediate pre-curing and final curing.The adhesion strength between the PI layer and the aluminum alloy substrate was higher than 10 MPa?Next,the effects of pre-set film thickness and laser processing parameter on the width,surface morphology and property of the conductive lines prepared by laser micro-cladding were studied.When the damage threshold temperature of the substrate increased,the critical laser power density of over-burning increased,resulting in the closer bonding between the conductive particles and the higher conductivity of film.In the condition of good adhesion strength,the volume resistivity of the silver films prepared on epoxy fiberglass substrate,PI and ceramic substrate were 26.8×10^-8??m,21.7×10^-8??m,7.1×10^-8??m,respectively.Slight damage of laser to the epoxy fiberglass substrate contributed to improve the adhesion strength.Lastly,basing on thermal analysis,scanning electron microscopy?SEM?analysis,etc.,considering the applied laser,paste composition and type,and substrate,it was found that the bad adhesion strength between the laser micro-cladding ruthenium oxide layer and epoxy fiberglass substrate resulted from the high content of the glass components in the ruthenium oxide paste and the overhigh melting point of ruthenium oxide.In summary,by the dry manufacturing of laser micro-cladding traditional thick-film electronic paste,the conductive patterns with controllable size and property were fabricated on the heat-sensitive polymer substrates.This was a beneficial attempt to manufacture electronic circuit and micro strip antenna by dry technology.