Experimental study on the effect of wire bonding by Cu electroplating on GMI stability of Co‐based amorphous wires

Abstract

In order to study the effect of wire bonding by Cu electroplating on giant magneto‐impedance (GMI) stability of microwires for potential sensor application. The electroplated microstructure was observed by scanning electron microscopy (SEM) and GMI was studied by a precision impedance analyzer placed in a magnetically shielded space. Experimental results indicated that after electroplating at a current intensity of 395.0 A/dm2 holding for 60 s with a two‐terminal electroplated length of 4 mm of the microwire, the Cu layer with a homogeneous and compact granular structure has higher adhesive strength between the wire and the Cu layer, better wettability between wire and SAC, lower contact resistance and coefficient of thermal expansion (CTE). Consequently, the wire bonding by Cu electroplating could enhance the conductivity and impedance stability under different applied field. It can, therefore, be concluded that the wire bonding by a Cu electroplating technique is suitable for electronic packaging for sensor applications.

Optimization of GMI properties by AC Joule annealing in melt‐extracted Co‐rich amorphous wires for sensor applications

“…Impedance measurements were performed using an Agilent 4294A precision impedance analyzer at 40 Hz–110 MHz . The GMI ratio, Δ Z / Z 0 , is defined as and the field sensitivity ξ of GMI is expressed as where Z( H ex ) is the impedance under external field, H ex (≤4.25 Oe), applied by a solenoid. Z ( H 0 ) is the initial impedance at 0 Oe.…”

The disparate impact of two types of GMI effect definition on DC Joule-heating annealed Co-based microwires

“…Recently, melt-extracted amorphous microwires have attracted much attention due to their various potential industrial applications, especially as giant magneto-impedance (GMI) sensor elements for detecting weak magnetic elds. [1][2][3][4] Compared with other fabrication techniques including rotating-water and glasscovered spinning, melt-extracted microwires without a glasscovered coating exhibit a higher cooling rate, which results in better mechanical and magnetic properties, such as superior so magnetic properties and large fracture strengths. This excellent performance makes melt-extracted microwires more suitable for applications in electronic packages and magnetic sensors, especially in GMI sensor elements.…”

Multiangle combined magnetic‐field annealing of Co‐based amorphous microwires for sensor applications

“…Amorphous magnetic microwires have recently attracted much attention from the research community because of their potential industrial applications, especially their utilization as GMI sensor elements to detect weak magnetic fields 1–5. Generally, as‐cast wires have a large‐tonnage residual stress, to influence their GMI performance and magnetic properties.…”