Preparation Of Polyimide/Silver Composite Film Based On In-situ Chemical Plating

Polyimide is one of the best comprehensive performance of polymer materials,and its stabilities,electrical properties,thermal properties,and so on are better than most other kind of materials.Polyimide films are the first commercial products of polyimide.In addition to its traditional application in the field of electrical insulation,polyimide has now been applied to the printed circuit board.By modifying the surface of the polyimide by alkaline solution,chemical bonds can be formed between the polyimide and metal,thereby preparing a composite film of polyimide and metal,but the method of metal surface in-situ package on polyimide has not been reported,yet.In this paper,the composite film can be prepared at the same time reducing the metal layer,forming a layer of nanometer-sized thickness polyimide layer,and thus play a self-encapsulated metal effect.Here,50?m polyimide films produced by Korea SKC Company was used to study the length of etching time,the length of ion exchange time,the length of heat reduction time and the basic strength of thermal reduction solution.The final experimental results show that the polyimide film needs to be etched in 4 mol/L KOH solution for 15-20 min,and the time of ion exchange is more than 30 min in 1 mol/L Ag NO₃solution,and when the volume ratio of ethylene glycol and triethylamine is 15:1 in the thermal reduction solution,with 5 min of the thermal reduction time,the Ag/PI composite film has the smallest surface resistance and the resistance is 1-2?,and the properties are the most balanced.The PI/Ag/PI composite thin film can be prepared by dissolving the saturated PAAS in the thermal reduction solution to form a solution.In this paper,PI/Ag/PI composite films were mainly characterized,the results of X-ray diffraction(XRD)show that the main components of the composite films are polyimide and silver,and the diffraction peak of silver is sharp,indicating that silver is mainly in the form of crystals;XPS shows that the composition of the surface of the films are polymer and elemental silver,and it illustrates the experiment successfully reduce Ag⁺ions to elemental Ag;and the RAS indicates that the main functional groups of the surface polymer are in accordance with the main functional groups of the polyimide,that is,the surface layer is a polyimide layer.Then morphology characterization of the composite film can be seen substantially layered structure,wherein the thickness of the metal layer is 200-300 nm,in line with morphology of expectations.In the part of characterization,the electrical and thermal properties of the composite films were characterized respectively.The surface resistance of the films could reach 10⁵-10⁶?and the surface insulation properties were good.And in the thermal stability characterization,the composite films do not decompose below 450?.The weight loss rate of the two kind of composite films was94.50%and 95.03%,respectively,and the content of Ag was about 3.52%and4.01%.At the same time,peeling strength is up to 0.05-0.12 N/mm.The method of preparing thin films can provide theoretical basis and process base for multi-layer space wiring,and has important value in enhancing the inter-laminar strength of composite materials,thin film self-assembly technology and the preparation of complex circuits.