Magnetic composite electroplating for depositing micromagnets

• Published in: Journal of microelectromechanical systems Vol. 15; no. 2; pp. 330 - 337
• Main Authors: Shan Guan, Nelson, B.J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Atoms & subatomic particles; Barium; Barium compounds; Coercive force; composite electoplating; Composite materials; Deposition; Dispersion; Electrolytes; Electroplating; Exact sciences and technology; Ferrites; Ferromagnetic materials; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Iron alloys; Magnetic analysis; Magnetic films; Magnetic particles; Magnetic properties; magnetics; Mechanical instruments, equipment and techniques; microactuators; micromagnetics; Micromechanical devices and systems; Particulate composites; Physics; Studies; Thin films; Actuators; Metals; Ferromagnetic materials; Microactuators; Dispersion reinforced material; X-ray spectroscopy; micromagnetics; Experimental study; Electroplating; Thin films; Magnetic alloy; Magnetic particles; Composite materials; Composite coating; composite electoplating; Electrodeposition; Magnetic materials; Microelectromechanical device; magnetics; Magnetic properties
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2005.863707

This paper reports a novel magnetic composite materials deposition technique called magnetic composite electroplating (MCE). Thin films and micromagnets arrays of a composite matrix consisting of magnetic particles and a ferromagnetic alloy have been fabricated based on this technique. In a typical MCE process, magnetic particles are electrochemically and mechanically embedded into electroplated ferromagnetic thin films to form a magnetic particle-alloy composite. The magnetic particle selected is a barium ferrite magnet (BaFe/sub 12/O/sub 19/) and the ferromagnetic matrix is a pulse-reverse electroplated CoNiP alloy. The particle embedded fraction (w.t. %) directly affects magnetic properties and is experimentally determined by its energy dispersive spectrum (EDS). Various factors including electrolyte particle concentration, applied current, electrolyte pH, and the presence of cationic surfactants affecting the particle embedded fraction are experimentally investigated. Arrays of BaFe/sub 12/O/sub 19/-CoNiP magnets with a variety of dimensions and features as small as 8/spl mu/m have been realized by MCE. Experimental analysis shows that the composite exhibits magnetic properties, such as a high coercivity (H/sub c/) of up to 1.75/spl times/10/sup 5/ A/m, particularly well suited for MEMS actuators.