The Preparation And Properties Of Silver-Coated Copper Powder Conductive Paste For Film Switch

This work aims to prepare low temperature curing silk screen conductive paste for film switches by using low cost silver-coated copper powder instead of silver powder.Firstly,the granular copper powder is prepared into a chip powder by a ball milling process,and the copper powder is used as a silver-coated substrate,and the coating is performed by a chemical replacement reduction method to obtain a silver-coated copper powder.Then,the powder was subjected to surface modification to obtain a powder having good dispersibility,which was prepared into a conductive paste,and the properties of the conductive paste were tested.On this basis,by comparing with the performance of silver conductive paste,the problems in the application of silver-coated copper conductive paste are summarized.Further,in response to these problems,combined with the characteristics of the silver-coated copper powder,the performance of conductive paste is improved by adjusting the composition of the carrier resin.A low-cost conductive paste using silver-coated copper powder as a main conductive filler was prepared.The study found that the specific surface area and oil absorption of silver-coated copper powder are quite different from those of silver powder.Since the dispersion characteristics of the silver-coated copper powder in the conductive paste are different from those of the silver powder,the rheological properties and printing characteristics of the conductive paste using silver-coated copper powder as a conductive filler are different from those of the conductive silver paste.In order to improve the performance of the silver-coated copper conductive paste,based on the characteristics of the silver-coated copper powder and the silver powder,the silvercoated copper powder mixed with pure silver powder is used as the conductive filler,by appropriately increasing the solvent content and reducing the fumed silica,and introduced PVB resin with better adhesion and toughness to build a composite resin carrier with PVB/P(VCVAc),a new type of silver-coated copper conductive paste was developed.When the mass ratio of the silver-coated copper powder to the pure silver powder is 1:1,the square resistance of the new silver-coated copper conductive paste is 28m?/?@mil;adhesion can reach 5B;hardness is 3H;the rate of change of resistance after heat aging and damp heat aging is less than 15%;storage ? 60 days.And it can meet practical application needs.Due to the use of low-cost silver-coated copper powder,the conductive paste has a 32% reduction in material cost compared to silver conductive paste.