Liquid Metal Based Low Resistance Interconnect Technology

Abstract

There is an increasing desire for interconnect technologies that provide low contact resistance, shorter electrical path and enable pin count scaling without the need for complex loading mechanisms. Ball grid array (BGA) technologies provide some of these benefits but add the complexity of surface mount challenges, especially on large form factor packages. Furthermore, customers value the flexibility of late and separable attach capability that sockets provide. Sockets, however come with a higher contact resistance and the required compression force drives significant cost and complexity to the loading mechanism. A liquid metal-based socket interconnect technology is introduced that offers BGA like performance with the benefits of a traditional socket. The liquid metal being studied is a gallium based eutectic alloy with a low melting point. The measured contact resistance is the lowest amongst available socket technologies and is equivalent to a permanently soldered down connection. The paper describes a process to manufacture a liquid metal interconnect and electrical characteristics of such an interconnect. This technology is in its infancy with insufficient data on field reliability risks or potential failure mechanisms when used as an interconnect. However, traditional evaluation techniques are less relevant for this novel interconnect and new methodologies are introduced to evaluate this technology.