Ali Roshanghias

Printed SAW transponder package for rapid prototyping of electronic packages

A great deal of attention has been attracted to the additive manufacturing technique of 3D printing in rapid prototyping of electronic packages. This technique enables fast and reliable production of complex structures with arbitrary configurations and possesses several advantages over the conventional manufacturing methods, such as mechanical machining and laser cutting. In addition, 3D printed packages can be considered as a try-out for the assessment of customized design prior to mass production, which will significantly reduce the expensive machining costs and material waste. This study proposes an innovative approach to construct simple radio frequency identification (RFID) package by integrating a surface acoustic wave (SAW) transponder in a 3D printed housing. On that account, an acrylate-type plastic SAW transponder housing was 3D-printed, and the corresponding wireless antenna and contact pads were produced via ink-jet printing with a silver nanoparticle (NP) ink. The proper functionality of the silver tracks was obtained by sintering the printed NPs using a photonic curing device. A flip-chip configuration has been pursued for connecting the chip pads to the corresponding pads on the housing. The performance of the package has been tested with a wireless reading unit via antenna-bridge for SAW transponders.

LiNbO 3 die-attach with Au-Ge eutectic solders

Lithium niobate (LiNbO3) single crystals are used as a promising piezoelectric material for high temperature sensors owing to its superior electromechanical coefficients and high frequency operation. The selection of materials and techniques for LiNbO3 die-attach aiming for the service temperature up to 300 °C encounters many objectives and practical considerations, where the processing temperature should be kept below 450 °C due to the decomposition of the die. Among the few candidates of lead-free solders exist in this temperature range, gold-germanium (Au-12 wt. % Ge) eutectic solder has shown promising characteristics. Therefore, in the current study, LiNbO3 die-attach to Hastelloy substrate with this solder was investigated. The mechanical properties of the corresponding assemblies were examined by a die-shear tester and the reliability of the joints has been assessed after thermal aging and thermal shock treatments at 300 °C.