A Low-Temperature Bonding Process Using Mixed Cu–Ag Nanoparticles

Abstract

A low-temperature bonding process to form joints with high strength and ionic migration resistance using mixed Cu-Ag nanoparticles was studied. Although it was difficult to obtain strong joints using Cu nanoparticles, with the addition of Ag nanoparticles to the Cu nanoparticles the bonding strength of the Cu-to-Cu joints increased. The joints formed by the mixed Cu-Ag nanoparticles at 350°C exhibited a high bonding strength of $50 MPa. Counterelectrodes made of the mixed Cu-Ag nanoparticles had four times higher ionic migration resistance compared with counterelectrodes made only of Ag nanoparticles.

A Low-Temperature Pressureless Bonding Process Using a Trimodal Mixture System of Ag Nanoparticles

“…It is difficult to obtain a dense sintered Ag layer without the bonding pressure. 1,2 The mean bonding strength of the Cu-to-Cu disc joints was clearly improved when using the mixture system of Ag nanoparticles, as shown in Fig. 3.…”

“…[6][7][8][9] The organic layer on the Ag nanoparticles was the same as for the Ag nanoparticles used in our previous study. 2,6 The mean diameter of the Ag nanoparticles was 20.2 nm (small nanoparticles: NP S ), 58.5 nm (medium nanoparticles: NP M ), and 168.0 nm (large nanoparticles: NP L ), respectively. The size and shape of these Ag nanoparticles were relatively uniform, as shown in Fig.…”

“…[1][2][3][4][5] Nanoparticles of various materials such as Ag and Cu have been evaluated as bonding materials because of their lower melting points than their bulk counterparts. The authors proposed a synthesis method for mass production of organically capped nanoparticles.…”

“…The bonding process is controlled by the features of the metallic nanoparticles, such as their size and the decomposition temperature of the organic layer. 1,2 To date, no studies have reported the concept of a bonding process using a mixture system of nanoparticles to increase the packing rate. In this study, a lowtemperature pressureless bonding process using a trimodal mixture system of Ag nanoparticles is investigated.…”

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.…”