Chang-Hyoung Lee

Ni full-filling into Al2O3/Al film with etched tunnels using a polyethylene glycol solution bath in electroless-plating

Ni/Al2O3/Al film was fabricated for a high performance capacitor using electrochemical etching, anodizing, and electroless-plating. The focus of this study was to form seamless and void-free Ni electrodes on Al2O3/Al with etched tunnels. The conventional deposition method of metal was limited to full-fill for the Al tunnel pits with a high aspect ratio, a depth of about 40 μm, and diameters of about 0.5–1 μm. Nevertheless, Ni filling in tunnel pits was achieved through electroless-plating for the first time, producing a seamless and void-free electrode. The authors used a polyethylene glycol solution bath to block the Pd on top of the tunnel prior to electroless-plating, which enabled the Ni to deposit preferentially at the bottom, leading to a filling from the bottom to the top. Finally, the capacitance density for the etched and Ni electroless plated films was 220 nF/cm2 while that for a film without any etch tunnel was 12.5 nF/cm2.

Reliability Evaluation for a Wet-Plated Electrode with a Al/Al2O3/Cu Insulated Metal Substrate

The heat sink in LED chips has been a major challenge for high-power LED module design. Elevated chip temperatures cause adverse effects on LED performance, lifetime, and color. An insulated metal substrate (IMS) is the commonly used substrate and has good thermal performance and low cost. This study used an aluminum IMS with good heat radiation efficiency to solve these problems. The most traditional IMS technique is electrochemical anodization. There are various methods to form electrical conductors on anodized aluminum. In this study, the anodization process was performed on an aluminum substrate using a phosphoric acid electrolyte to form the AAO layer. This investigation confirmed that electroless Ni-P plating for seed layers could be used to substitute for the Cu-sputtering process. Our evaluation of the reliability of the different thicknesses of aluminium anodic oxidation and the electro-plated Cu electrode revealed that the maximum peel strength was 1.6 kgf/cm and it was obtained at an anodizing time of 1000 minutes. The TCT, the solder shock test and the solderability test showed that the substrates were not delaminated. †(Received October 15, 2012)

Preparation and Characterization of (Ba0.8Sr0.2)TiO3–Al2O3 Composite Oxide for Thin Film Capacitor

Barium strontium titanate–alumina composites were fabricated using a sol–gel and anodizing process for high performance thin film capacitors and the properties of the films were studied. The (Ba0.8Sr0.2)TiO3 (BST) films were formed by spin coating and subsequent annealing at 150–550 °C. The respective annealed films were anodized in a neutral borate solution. The capacitance density increased with increasing annealing temperature up to 450 °C but decreased at 550 °C. The capacitance density was approximately 28.46% higher with the BST coating than without the BST layer.