New Industry Products

Toyochem Introduces Sintering Nano-Silver Pastes 

May 13, 2023 by Mike Falter

Toyochem introduces sintering nano-silver pastes engineered for power electronics bonding in automotive applications. 

Toyochem, the polymer materials division of Toyo Ink Group in Japan, introduced sintering nano-silver pastes specially engineered for power electronics bonding in automotive applications at PCIM Europe 2023 this week.  

The company has been innovating in the polymer design space for over 100 years, offering a range of polymers, adhesive tapes, marking films, and coatings for electronics manufacturing and industrial applications.


Developing polymer adhesives

Developing polymer adhesives. Image used courtesy of Toyochem


Thermal Conductive Silver Pastes for Component Bonding

For its nano-silver pastes, Toyochem uses proprietary nanoparticle design and dispersion technologies for a bonding material that is easy to print, has strong bonding characteristics, and is great at conducting heat to the environment with a typical thermoelectric conductivity of 300 W/m-K.

As an alternative to traditional solder, which requires full melting and reflow, sintering is the process by which materials are bonded through the application of high pressure and temperatures over time. Component bonding with silver sintered pastes is a good alternative to traditional solder pastes since they are lead-free, have a much higher lifetime, and have better thermal conductivity. 

Silver pastes can also operate at much higher temperatures than traditional solder materials. This is a critical feature for power-dense EV inverter and battery charging circuits typically constructed with high-voltage silicon carbide (SiC) and gallium nitride (GaN) switching components.  

SiC MOSFET placement with silver sintering material

SiC MOSFET placement with silver sintering material. Image used courtesy of Indium

Importance of Thermal Conductivity

Unlike an insulator, a good thermal conductor easily passes heat to the environment or other conductors like heat sinks. In auto electronics and other power-dense systems, silver pastes, with their high thermal conductivity, facilitate the flow of heat from power devices to adjacent materials (heat sinks, PCB, packaging materials, etc.), where excess heat can then be dissipated to the environment, all while maintaining a strong mechanical bond at the contact surface.  

Heat transfer can be described mathematically through Fourier’s Law of Thermal Conduction:

q = -k∇ T

Where q is the heat flux in W/m2 and ∇T is the temperature gradient across the material defined in units of K/m (kelvin per meter). With a little math, the thermal conductivity (k) can be derived with the units of W/m-K (watts per meter-kelvin).

So, for a given heat flux, or amount of heat passing through a material, a higher thermal conductivity reduces the temperature gradient with the external environment and prevents internal components from exceeding their thermal limits.   

Thermal conductivity of a material

Thermal conductivity of a material. Image used courtesy of C-THERM


Continued Innovation in Thermal Management 

As energy, e-mobility, and similar applications push to higher power density levels, expect to see continued innovations in thermal management, including more efficient power conversion systems, power devices that can operate at higher temperatures, and assembly materials with better thermal conduction properties, like nano-silver pastes.