Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review <s> (c) Electrodeposition Technology <s> We have developed a cheap and simple trilayer printed circuit board (PCB)-based technology, adapted for the fabrication of fluxgate magnetic sensors. The two outer layers of the PCB stack comprise the electrical windings of the fluxgate, while the inner layer is made of patterned amorphous magnetic core with extremely high relative magnetic permeability (µr100,000). The output voltage and the sensitivity of the fluxgate devices have been studied as a function of the external field and of the geometry of the magnetic core. We have found a relatively high sensitivity of 18 V/T at an excitation current frequency of 10 kHz. The results obtained clearly show the potential of this miniaturised fluxgate device for application as a magnetic field sensor. Keywords: Fluxgate sensor; Sensitivity; High permeability; Compass; Vitrovac®; Printed circuit board (PCB) <s> BIB001 </s> Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review <s> (c) Electrodeposition Technology <s> Abstract Micromachined electronic compass integrating two-axis micro-fluxgate sensors was investigated. These sensors were perpendicularly aligned to measure the magnitude of X- and Y-axis magnetic fields, respectively and each of them was composed of rectangular-ring shaped magnetic core, solenoid excitation (49 turns), and pick-up (46 turns) coils. Excitation and pick-up coil patterns, which were formed opposite to each other, wound the magnetic core alternately to improve the sensitivity. In order to induce magnetic anisotropy, the magnetic core(Ni0.81Fe0.19 permalloy) was electroplated under the external magnetic field of 2000 G The fabricated core has dc effective permeability of ∼1250 and has the characteristics to be easily saturated due to the low coercive field of ∼0.1 Oe and closed magnetic path for the excitation field. The size of each micro-fluxgate sensor excluding pad region was about 2.6 mm ×1.7 mm. The fabricated two-axis micro-fluxgate sensors have excellent linear response over the range of −100 to +100 μT with 210 V/T sensitivity at the excitation condition of 2.8 VP–P and 1.2 MHz square wave. The power consumption was estimated to be ∼8.5 mW and perming effect was suppressed below 1.7 μT for the magnetic field shock of 60 G. <s> BIB002
Another technology combines PCB technology with the electrodeposition of Co-P alloys BIB002 . This system has, among others, the great advantage of avoiding the use of glue to adhere the core to the device. For example, the device developed by Dezuari et al. BIB001 is based upon various one and double faced plates in which the tracks are obtained by means of photolithography. This method allows to produce fluxgates with a maximum sensitivity of 160 V/T with a flow between 300 mA and 10 kHz.