Embedded Planar Power Inductor in an Organic Interposer for Package-Level DC Power Grid

To realize the basic technology of a package-level dc power grid for the next generation power delivery to large scale integrated circuits (LSIs), two types of planar spiral inductors embedded in an organic interposer, for several tens of megahertz switching power supply integrated in LSI package, have been proposed. One is a Zn-Fe ferrite core spiral inductor, and another is a hybrid core spiral inductor, with quasi closed magnetic circuit consisting of the bottom Zn-Fe ferrite core and top carbonyl-iron/epoxy composite core. In this paper, the two types of planar spiral inductors have been fabricated and evaluated. From the experimental results, it was found that the hybrid core planar spiral inductor exhibited higher Q-factor and larger rating dc current than the Zn-Fe ferrite core inductor.ArticleIEEE TRANSACTIONS ON MAGNETICS. 50(11):8401304 (2014)journal articl

Intramolecular Hydrogen Atom Transfer Hydroarylation of Alkenes toward δ-Lactams Using Cobalt-Photoredox Dual Catalysis

Intramolecular hydroarylation of alkenes through hydrogen atom transfer (HAT) represents a robust method to prepare benzo-fused heterocycles. However, the reported methods have limitations in a variety of accessible cyclic scaffolds. Here we report a dual cobalt- and photoredox-catalyzed HAT hydroarylation of alkenes that is characterized by higher efficiency in the synthesis of a δ-lactam compared to established protocols. The proposed mechanism is supported by experiments and DFT calculations

Silane- and peroxide-free hydrogen atom transfer hydrogenation using ascorbic acid and cobalt-photoredox dual catalysis

Hydrogen atom transfer (HAT) hydrogenation has recently emerged as an indispensable method for the chemoselective reduction of unactivated alkenes. However, the hitherto reported systems basically require stoichiometric amounts of silanes and peroxides, which prevents wider applications, especially with respect to sustainability and safety concerns. Herein, we report a silane- and peroxide-free HAT hydrogenation using a combined cobalt/photoredox catalysis and ascorbic acid (vitamin C) as a sole stoichiometric reactant. A cobalt salophen complex is identified as the optimal cocatalyst for this environmentally benign HAT hydrogenation in aqueous media, which exhibits high functional-group tolerance. In addition to its applicability in the late-stage hydrogenation of amino-acid derivatives and drug molecules, this method offers unique advantage in direct transformation of unprotected sugar derivatives and allows the HAT hydrogenation of unprotected C-glycoside in higher yield compared to previously reported HAT hydrogenation protocols. The proposed mechanism is supported by experimental and theoretical studies

Embedded Planar Power Inductor in an Organic Interposer for Package-Level DC Power Grid

To realize the basic technology of a package-level dc power grid for the next generation power delivery to large scale integrated circuits (LSIs), two types of planar spiral inductors embedded in an organic interposer, for several tens of megahertz switching power supply integrated in LSI package, have been proposed. One is a Zn-Fe ferrite core spiral inductor, and another is a hybrid core spiral inductor, with quasi closed magnetic circuit consisting of the bottom Zn-Fe ferrite core and top carbonyl-iron/epoxy composite core. In this paper, the two types of planar spiral inductors have been fabricated and evaluated. From the experimental results, it was found that the hybrid core planar spiral inductor exhibited higher Q-factor and larger rating dc current than the Zn-Fe ferrite core inductor.ArticleIEEE TRANSACTIONS ON MAGNETICS. 50(11):8401304 (2014)journal articl