Migration of Sintered Nanosilver Die-Attach Material on Alumina Substrate Between 250 $^{\circ}\hbox{C}$ and 400 $^{ \circ}\hbox{C}$ in Dry Air

Investigation of Post-Etch Copper Residue on Direct Bonded Copper (DBC) Substrates

“…The activation energy of migration could drop below 0.77 eV at high temperatures, 20 a value lower than that of silver. 22 Secondly, copper is easily oxidized at high temperatures. More attention needs to be paid to the copper residue issue in the future.…”

“…An indication that copper is even more susceptible to migration than silver was thereby confirmed. 20,22 The low activation energy of migration is the reason why copper could migrate through Ni, Au, or Ag surface. 26 So, silver electrodes do not prevent migration of copper residue, and this is why we use them in our study here.…”

“…The black dendrites had been confirmed as silver by EDS in our previous work. 22,27 To identify the yellowish dendrites, we used scanning electron microscopy (SEM) and EDS.…”

“…So it is possible for copper to be ionized, shifted between electrodes, and deposited into copper at the other electrode. 22 Since copper residue can migrate between conductors at 400°C and 50 V/mm with the protection of silver, it could become a reliability issue in DBC applications, especially at high temperatures. First, the copper dendrites could lower the surface resistivity of alumina.…”

Are Sintered Silver Joints Ready for Use as Interconnect Material in Microelectronic Packaging?

“…34,35 As shown in the Ellingham diagram, silver oxides are thermally unstable, and they can easily reduce to metallic Ag at temperatures above 250°C to allow sintering to occur. 36 In the presence of oxygen, Ag atoms diffuse to neighboring Ag atoms at temperatures as low as 184°C for the initiation of sintering. 37 The typical sizes of these Ag fillers ranges from 0.1 to 10 lm 34,35 and up to a maximum of 18 lm.…”