Low temperature thermo compression bonding with printed intermediate bonding layers

The paper describes capabilities of additive material transfer technologies Aerosol Jet Printing (AJP), Stencil Printing (STP) and Screen Printing (SP) based on nano particle inks with the purpose of intermediate bond layer manufacturing for Chip-to-Chip, Chip-to-Wafer and wafer level bonding. For realization of these applications, the deposition process and the related material morphology, the bonding with nano particle based intermediate bonding layer (IBL) as well as the characterization methods are described. AJP was used to deposit silver (Ag) as IBL to bond copper (Cu) and gold (Au) metallized wafers. Stencil printed Au nano particle IBL layers were used to bond Au metallized wafers. The interface between nano particles and substrate were investigated. For bonding result evaluation, bonding frames and occurring bonding interfaces were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and focused ion beam (FIB). Mechanical properties were qualified using compression shear tests and tensile tests.