POWER MILGOLD LIMITED.
SiC Power Device
Silver Sintering Solution
Key Technology of EV Power Device Chip Attaching, Sintering Nano Silver Paste
“The fact that the operating temperatures of SiC device packages now reach a scorching 225ºC, and the likes of Wolfspeed, ROHM, Infineon and GeneSiC have been busy pioneering new packaging structures to better handle the extreme switching speeds and temperatures.”
“At the same time, innovations, such as the use of copper connections and silver sintering joints instead of aluminium wire bonds and solder joints, have also emerged.”
Recently Tesla adopted silver sintering applied SiCpower module to Model 3
SiCPower Device
SiC is a next-generation material capable of high power and high temperature operation compared with Si, promising fast switching speed, and1/10 size can be possible based on the same performance as Si.
Die Attach for SiC
To achieve high voltage and power, high temperature operation is essential
Since sintered silver is very similar to bulk silver(melting point 960℃), robust strength is achieved.
On the other side that It is obvious that tin based solder’s melting point(mostly 170~230℃)is not high enough
To have high power applications, sintering silver is essential
Without the sintering, uncoupled void is always existed among particles. And it causes the rapid decrease of shear strength and thermal conductivity
For convenient and economical process, sintering condition must be mild
Sintering temperature of silver:
Bulk Silver : Over 950℃
Micro Size Silver : 550 ~ 700 ℃
Nano Size Silver 200 ~ 300 ℃
High sintering temperature→ Constraint on applications
To reduce sintering temperature, expensive equipment and risky process are needed → Pressure Assisted Sintering(5~20bar)
Poor material selection – no organic compounds for other components
Pressure-less Low Sintering Temperature Silver
General Information
Size : D50 -50nm
Synthesis method : wet type
Morphology : spherical
Color : Dark grey to black
Cured(150℃ X 30min+230℃ X 30min) adhesive properties (Film thickness: 100㎛)
Volume Resistivity: 6x 10-6Ω∙㎝
Thermal Conductivity:Over 200 W/m∙K Laser Flash Method
Nano Silver Capping Technology
Utilizing extremely low activating energy
→ Dispersion with low bonding energy
PMG capping technology allows that silver particles are maintained as nano-sized
Specially capped nanosilver can be sintered within 200℃ which is the world best performance
Capping is essentially required to prevent particle growing
At the same time, de-capping must be worked at Low temperature
