Study Of A New Type Of Magnetic And Conductive Composite Filler And Characterization

A new type of magnetic and conductive composite filler was developed. Silver was chemically deposited to the Fe₃O₄ powder surface by the electroless plating technique,the preparation processes of the Ag-Fe₃O₄ composite filler were tried. Electroless plating silver to Fe₃O₄ powder in dextrose-silver-ammonia and formaldehyde-silver-ammonia solutions respectively under ultrasonic strring,was developed to prepare Ag-Fe₃O₄ composite filler. The affect conditions in terms of the bath composition,the PH value,the bath temperature,the reaction duration,the way of strring,the usage of Fe₃O₄ powder and the different additives on silver electroless plating on the Fe₃O₄ powder were studied. The morphology and composition of the Ag-Fe₃O₄ composite filler were characterized by Scanning Electron Microscopy (SEM) and EDS techniques. Its magnetism was characterized by VSM . The results showed that the conductivity of the composite filler with formaldehyde as reductant was better than that of dextrose and the yield of Ag-Fe₃O₄ composite filler using formaldehyde as reductant was higher than that of dextrose . The composite filler with high conductivity had the structure of core-shell,and the proportion of Ag to Fe was 55.17 to 37.84 per mol,the PH value was controlled within 10 to 12,the reaction duration were 80 minutes . The saturation magnetization of the composite filler was 20.61emu/g at 273K, the remanence was 7.07emu/g,the coercive force was 153Oe.A new kind of conductive adhesive was prepared from Ag-Fe₃O₄ composite filler and CYD-128 epoxy resin in the project. The triethanolamine as curing agent,acetone as thinner.The morphology of the conductive adhesive was characterized by Scanning Electron Microscopy (SEM). The relationship of volume resistivity of the conductive adhesive with the curing conditions were studied in terms of temperature, on the curing duration,the usage of Ag-Fe₃O₄ composite filler. The results showed that the curing temperature was 125℃,the curing duration two hours. The optimization bath composition was:2.0gram Ag-Fe₃O₄ composite filler , 0.6gram CYD-128 epoxy resin , 0.2gram triethanolamine and 0.1gram thinners. The volume resistivity of the conductive adhesive based Ag-Fe₃O₄ composite filler was 1.52×10^-3Ω.cm that was lower than the copper based conductive adhesive whose resistivity was 4.0×10^-3Ω.cm . Comparison with the copper base filler adhesive,Ag-Fe₃O₄ composite filler adhesive could avoid copper oxidation,cut down of the material cost compared with the copper filler adhesive. In addition,this conductive adhesive also had magnetism. The multifunctional conductive adhesive will have good market prospect for its advantages of good conductivity and magnetism with low material cost.