Nanosolders allow for increased capabilities in the formation of soldered interconnections for heat-sensitive electronic packages. The desired characteristic of nanosolder is to have a low process temperature that does not damage base materials or components, while also having a high service temperature that allows the product to operate in harsh environments.
A robust nanosolder was developed that meets these objectives, and is inexpensive and easy to use in an assembly process. The nanosolder begins with a mixture of copper and silver nanoparticles in a toluene-based vehicle, that when heated to 150 °C, forms a 3D epitaxial copper core and silver shell structure. The silver shell acts as a protective coating, creating a solder that remains stable when in contact with air until the melting step occurs to form the joint. This approach eliminates the need for specialized equipment to inert the environment.
Unlike traditional lead-free solders, the finer structure of the nanosolder permits lower reflow processing temperatures, resulting in less thermal stress during processing. The nanosolder can enable further miniaturization of electronics by enabling the development of a broader range of products without the risk of thermal damage to heat-sensitive materials and components.
Potential applications for the nanosolder include microelectromechanical systems (MEMS), joining of carbon nanotube and additive manufactured materials and parts, and assembly of complex sensors and optoelectronic products.