Improved sinterability of particles to substrates by surface modifications on substrate metallization

Sintering under pressure has been in the forefront of the research and development over the past decade as an alternative to high temperature soldering and die-attach bonding for high temperature electronics. However, high bonding pressure is a deterrent to mass industrialization due to the high costs involved in the design of special tooling and complex process control parameters. Further, it can cause device cracking, especially while working with sensitive high power optoelectronics devices (e.g. high power light emitting diodes). Therefore, alternatives to enhance sinterability are highly requested. Substrate metallization is observed to play an important role while sintering. An innovative low cost method to have nanostructured surface modifications on the substrates is realized and presented here. The method is applied to enhance sinterability of Cu particles to substrate. Shear tests on samples with surface modified substrates are promising with results of ca. 25 MPa, which is 24% better than sintering on unmodified bare Cu substrate. Sintering was enabled by in-house developed hybrid Cu paste under pressureless sintering conditions of 300°C, for 60 min, and under N2 atmosphere.