Effects of Joining Conditions on Joint Strength of Cu/Cu Joint Using Cu Nanoparticle Paste

Abstract

High-temperature bonding, or joining, is a key technology for electronic component assembly and other hightemperature applications. Recently, focusing on the sintering behavior of nanoparticles, the joining process using a nanoparticle paste has been proposed as an alternative to soldering for high-temperature applications. In this study, Cu nanoparticle paste was used to join two Cu discs, and the effect of joining conditions on the joint strength of the Cu-to-Cu joint was investigated. Joining using Cu nanoparticle paste was successfully achieved, but the effect of joining conditions such as heating temperature and joining atmosphere on joint strength of the Cu-to-Cu joint was significant.

Microscale Ag particle paste for sintered joints in high-power devices

“…When the nanoparticles are heated, sintering takes place between them, producing a bulk-state bonded layer. The sintering behavior of metal nanoparticles such as Ag and Cu has been exploited to write electronic circuits and join components to substrates [5][6][7][8][9]. For example, Ide et al [5] achieved Cu-to-Cu joining using Ag metallo-organic nanoparticles at a low bonding temperature (300 °C) and a bonding pressure of 1 or 5 MPa; the shear strength of the resulting joints was 25-40 MPa.…”

Joining of Pure Copper Using Cu Nanoparticles Derived from CuO Paste

“…It has been reported that the ECM tolerance can be improved by using a composite paste made by adding Au and Pd particles to a Ag 2 O paste. 16) Moreover, a bonding process using Cu nanoparticles has been researched 17,18) because it is known that the ECM tolerance of Cu is higher than that of Ag. However, once again these bonding materials still do not reduce the cost to a level sufficient for widespread commercial use.…”

Shear strength of Cu-to-Cu joints using mixed Ag particle paste

“…For example, Au-, Zn-and Bi-based alloys have been investigated, but their widespread use is unlikely because of their inferior properties and high costs [2][3][4][5][6][7][8][9] . New joining process using thin films and sintering process using metal particles have also been proposed as solder alternatives [10][11][12][13][14][15] . Especially the sintering behavior of metallic nanoparticles has been exploited to write electronic circuits and join components to a substrate.…”

“…Bonding was believed to occur because of the large surface energy contributed by the nanoscale particles. As Cu-to-Cu bonding using a nanoscale copper particle paste, Nishikawa et al 13) reported that the effect of joining conditions on the shear strength of Cu-to-Cu joints using a nanoscale copper particle paste was investigated and joints that were bonded at 400 ºC for 300 s under a joining pressure of 15 MPa showed high shear strength around 40 MPa. However, there are some drawbacks of bonding process using nanoscale particle pastes; for example, it is difficult to produce suitable nanoscale particle pastes for the processing and the residual organic materials after the joining process can induce unexpectedly large gaps and voids in the joint area 16,17) .…”