The reliability of ENIG joint bonded by In-coated Cu sheet

To meet the increasing demand of the next-generation power conversion circuit on the high-power density, high operating temperature and miniaturization, many novel packaging methods have been investigation. Due to high remelting temperature and low cost transient liquid phase (TLP) bonding technology shows the great potential. In this paper, ENIG-finished Cu disks were bonded by In-coated Cu sheet through TLP bonding at 250°C and the shear test as well as fracture analysis during thermal aging was conducted. The bonded joint with the Cu
2
In, Au-In-Cu and Ni
2
In
3
IMC interface showed a strength of 19.85 MPa, although some defects could be observed. During thermal aging, the Cu
2
In and Ni
2
In
3
coarsened and the interface became more compact. It was very interesting that the shear strength of joint was increased by 81.21 after 1008 h thermal aging at 250°C. Although the fracture location was changed during thermal aging, the fracture surface always showed brittle characteristics.