High-density double-layer printed circuit board (PCB) inspection based on the eddy-current testing (ECT) technique is proposed in this paper. The ECT probe, which consisted of a planar meander exciting coil and spin-valve giant magnetoresistance (SV-GMR) sensor array, is used for this propose. Defects on both the top-and bottom-layer of the high-density double-layer PCB are examined by the ECT technique with scanning over either the top or bottom layer. The characteristics of the proposed ECT probe for high-density double-layer PCB inspection are studied. The inspection results of the high-density double-layer PCB model verify that applying the ECT technique enables identification of the defects of both the top and bottom layer with one-side scanning.Index Terms-Eddy-current testing (ECT), inspection, printed circuit board (PCB), spin-valve giant magnetoresistance (SV-GMR).
High modulus carbon fibers without surface treatment were incorporated into aluminum alloys by the squeeze casting process. The chemical interaction between fibers and matrix, and its effects on the composite strength and fracture morphology were investigated. The effects of alloying elements of Cu, Ca and Mg were also investigated.The strength and modulus of the composites are in good agreement with the values predicted by a simple rule of mixtures. It is found that the shear strength of the composites is improved by Mg and Ca additions to the matrix and by heat-treatment of the composites. The carbon diffused into the matrix in as cast Al-Mg and Al-Ca alloy matrix composites. The shear fracture path is through the fiber-matrix interface in pure aluminum and Al-Cu matrices, and is through the interface region containing alloying elements in Al-Mg and Al-Ca alloy matrices.
Multifilament type silicon-carbide fiber-reinforced aluminum alloys and a new type of fiber composite, in which whiskers or particulates are distributed among continuous fibers, were prepared by squeeze casting. The mechanical properties and fracture behaviour of the composites were investigated.The hybrid composites were superior in the strength to the conventional fiber composites. The tensile strength of the composite with hybrid reinforcements of fibers and fine particulates coincided with the strength predicted from the simple rule of mixture. The effect of the addition of whiskers or particulates is to maintain fiber separation during composite fabrication, followed by inhibition of the direct fiber contact in the composites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.