Improvement on defect detection performance of PCB inspection based on ECT technique with multi-SV-GMR sensor

金沢大学環日本海域環境研究センター生体機能計測研究部門This paper describes the improvement on the defect detection performance of printed circuit board (PCB) inspection based on the eddy-current testing (ECT) technique with the multispin-valve giant magnetoresistance (SV-GMR) sensor. To obtain the ECT signal in the same scanning line, SV-GMR sensors are mounted on the exciting coil in the same column parallel with the scanning direction. Harmonic analysis based on the Fourier transform is used to analyze the signal from the SV-GMR sensor in order to increase scanning speed. Then signal averaging is applied to the ECT signal in order to improve the signal-to-noise ratio. Experimental results are performed to verify the inspection performance. © 2007 IEEE

Bare PCB inspection system with SV-GMR sensor eddy-current testing probe

金沢大学環日本海域環境研究センター生体機能計測研究部門This paper describes bare printed circuit board (PCB) inspection based on eddy-current testing (ECT) technique with high scanning speed. A high-frequency ECT probe composed of a meander coil as an exciting coil and the spin-valve giant magnetoresistance (SV-GMR) sensor was fabricated and is proposed. The ECT probe was designed based on crack inspection over flat surface, especially suitable for microdefect detection on high-density bare PCB. The ECT signal detected by the SV-GMR sensor was acquired by high-speed A/D converter for applying the signal processing based on digital technique. Harmonic analysis based on Fourier transform was used to analyze the ECT signal at fundamental frequency in order to increase inspection speed and this technique allowed the ECT probe to scan bare PCB, with high sampling frequency and with high-spatial resolution inspection. Experimental results verified the possibility and the performance of the proposed PCB inspection system based on ECT technique. © 2007 IEEE

Application of Giant Magnetoresistive Sensor for Nondestructive Evaluation

金沢大学環日本海域環境研究センター生体機能計測研究部門This paper describes the applications of spin-valve type giant magnetoresistance sensor (GMR) for nondestructive evaluation. One is the eddy-current testing (ECT) probe which enables us to inspect micro defect and to detect micro conductors. The proposed ECT probe was applied to the inspection of bare printed circuit board and the recognition of micro solder bead for IC surface mounting package. Another is the measurement of the density of magnetic fluid injected in living body for the hyperthermia treatment. For this purpose, the needle type GMR probe was developed. The experimental results verify the possibility of the proposed system. © 2006 IEEE

Conductive microbead array detection based on eddy-current testing using SV-GMR sensor and helmhlotz coil exciter

金沢大学環日本海域環境研究センター生体機能計測研究部

Conductive Microbead Array Detection Based on Eddy-Current Testing Using SV-GMR Sensor and Helmholtz Coil Exciter

This paper describes the detection of both single and array conductive microbead (PbSn) by using a spin-valve giant magnetoresistance (SV-GMR) as a sensor and the Helmholtz coil as an exciter based on eddy-current testing (ECT). Experiments were performed to detect a single and array conductive microbead, with three models. Each model consists of 4 x 4 microbeads but the microbead diameter and pitch were slightly different for each array. The microbead radius was 125 μm and the pitch was 500 μm. The ECT method was used to estimate the position of the centers of the microbeads and the error in the measurement was plotted on a plane. A good level of position resolution has been achieved and the signals were quite clear

Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO3_3

First-principles density functional calculations are performed within the local density approximation to study the electronic properties of SrZrO$_3$, an insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as well as the generic 3d-perovskite SrTiO$_3$, which is also a d^0-insulator and cubic above 105 K, for comparison reasons. The energy bands, density of states and charge density distributions are obtained and a detailed comparison between their band structures is presented. The results are discussed also in terms of the existing data in the literature for both oxides.Comment: 5 pages, 2 figure

Estimation of Low-Concentration Magnetic Fluid Density with GMR Sensor

This paper describes a new application of a spin-valve type giant magnetoresistance sensor in the biomedical field. The hyperthermia treatment, based on the hysteresis loss of magnetite under external ac fields, requires determination of the content density of magnetite injected inside the body to control the heat capacity. We propose a low-invasive methodology to estimate the density of magnetite by measuring magnetic fields inside the cavity. For this purpose, we investigated the relationship between the density of magnetite and the magnetic fields, and developed a needle-type magnetic probe with a giant magnetoresistance sensor for low-invasive measurement. The experimental results demonstrate the possibility of estimating the low-concentration density of magnetite injected into the body. © 2008 American Institute of Physics