Front Cover: Experimental study on the effect of wire bonding by Cu electroplating on GMI stability of Co-based amorphous wires (Phys. Status Solidi A 3/2011)
Jing-Shun Liu, Jian-Fei Sun, Da-Wei Xing, Xiang Xue, Shu-Ling Zhang, Huan Wang and Xiao-Dong Wang
Article first published online: 8 MAR 2011 | DOI: 10.1002/pssa.201190007
The image on the front cover refers to the article by Jing-Shun Liu et al. (pp. 530–534). It shows the giant magneto-impedance (GMI) output stability of Co-based amorphous wires with nonelectroplated and Cu electroplated wire bonding at the wire ends, measured by a precision impedance analyzer placed in magnetically shielded space (MSS). The wire bonding by nonelectroplating (top image) displays an inhomogeneous variation region (IVR), whereas Cu electroplating (bottom image) could enhance greatly the GMI output stability and conductivity under different applied fields. Here, the excellent bondability, wettability and the coefficient of thermal expansion (CTE) of wire weld spots could reduce the emission of radio-frequency noise signal and the disturbance by stray capacity. Thus destabilization and concussion resulting from contact instability of the wire-bonding ends can effectively be suppressed at relatively high frequency (MHz). It can therefore be concluded that wire bonding by the Cu electroplating technique is suitable for electronic packaging in sensor applications.