Dissipation Coefficient And Conductive Behavior Of Liquid Metal Polymer Composites

Although current anisotropic conductive adhesives(ACAs)have achieved great success in electronic industry,the design of ACAs has followed similar mechanisms and protocols for more than 40 years with a couple of challenges limiting their broad and advanced applications,such as complicate operating techniques,high processing temperature/pressure and limited functionalities.Attributed by the unique mechanical and electrical properties,functional blends of liquid metals(LMs)and polymers have received lots of attention.The deformation of LM-polymer materials under extreme force to create electrical conductivity has built many electronic applications.However,the fundamental understanding of the relationship among polymer networks,LM deformation,and electrical conductivity remains too opaque to have a general principle for further advanced LM-polymer electronics.In this paper,liquid metals(LMs)as conductive and flowing fillers in polymers provide a new generation of ACA(LMACA).In this work,a series of liquid metal-polymers with different glass transition temperatures(T_g)were prepared by physically blending liquid metal with epoxy resin E-51,ecoflex rubber,vytaflex polyurethane,and PDMS rubber.This work discovered that the energy dissipation of polymer matrix plays a determinative role in controlling the electrical behaviors of LM-polymers.When the energy dissipation coefficient of liquid metal-polymer is than 40%,the external pressure successfully disrupts high energy dissipated(HED)polymer networks and cracks LM fillers to provide anisotropic conductivity along pressure direction while insulated in planar directions.However,this transition in conduction behavior does not occur in liquid metal-polymers with energy dissipation coefficients below 31%.In addition,this thesis prepared a liquid metal-polyimide anisotropic conductive material with the same function on the basis of liquid metal-epoxy polymer.LM-epoxy resin exhibits the unique‘curing-first’character,which achieves the‘printing action’for customized circuits after adhesion.Meanwhile,liquid metal-epoxy resin and liquid metal-polyimide can achieve electrical response under bending force response,so they are particularly suitable for application in flexible electronic products.The preliminary LMACAs fulfilled the requirement of electronic engineering as traditional ACAs and were successfully utilized in practical integrated circuit boards.