| With the development of miniaturization and thinness of electronic devices,the problem of warping and thermal expansion coefficient mismatch caused by high temperature connection becomes more and more serious.For conductive adhesive with low curing temperature can be connected to fine structure,it has attracted more and more attention.Traditional conductive adhesive is usually silver conductive adhesive,which has the disadvantage of high cost and easy electrochemical migration.Although using silver adds to the cost,copper is easy to be copper oxide,which greatly limits its application scope.Therefore,the use of silver coated copper material can not only reduce costs,but also reduce the oxidation of copper and its electrochemical migration resistance can be improved,the silver-coated copper powder preparation process is not mature,the uniformity of cladding layer is not certain.So this paper aiming at the synthetic process of silver-coated copper powder,comes up with two-step preparation of silver and copper clad granules,and applies silver copper clad granules preparation of conductive paste and conductive adhesive,the final preparation for UHF RFID tags.To solve the problem of incomplete coating of silver-coated copper powder,a two-step method was proposed to prepare silver-coated copper particles.The influences of different reducing agents,like glucose,dispersants and reaction temperature on the silver coating layer were investigated,and an innovative method was proposed to treat the seed layer with ammonia water to obtain a more uniform coating with smaller silver particles,with the second step reaction following.Based on two-step appearance as the gray,silver-coated copper powder preparation after tablet has 0.198 m?/? sheet resistance.Thermogravimetric analysis showed that the antioxidant capacity of silver coated copper powder prepared by two-step method was greatly improved.To solve the problem of high cost and easy electrochemical migration of traditional silver paste,silver-coated copper conductive paste was prepared.The differences in the properties of conductive pastes prepared by different adhesive phases of water system,alcohol system and resin system were investigated.And this paper also studied the influence of additives,conductive filler content and curing temperature on conductive paste.Finally identified the best prescription for conductive paste,through the wire mesh screen printing machine printing,cured at150 ? environment and the conductive films had the adhesion of 5B,3H hardness,192 m?/? sheet resistance and the resolution of the 20 microns.The results show that the electromigration resistance of silver-coated copper powder prepared by the twostep method is much better than that of silver powder.For the traditional silver conductive adhesive is high cost and easy electrochemical migration,the silver-coated copper conductive adhesive was prepared.In order to get the optimum fesin system,this paper investigated the curing and storage properties of different epoxy resins combined with different curing agents Through exploring the conductive filler content on the properties of conductive adhesive,determined to 65 wt.% of conductive powder content in the preparation of anisotropic conductive adhesive,which had 953 m? contact resistance,and the shear performance of 15.63 MPa.In this paper,the silver coated copper conductive paste was used to prepare RFID tag antenna,and the silver coated copper conductive adhesive was used as the binder of RFID tag chip and antenna to prepare UHF RFID tag.The RFID tag had a reading distance of about 4 m in the frequency range of 860MHz?980 MHz,and had a prospect of application in wireless sensor,automatic charging,public transportation,book management and other aspects. |
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