Au Coated Printed Circuit Board Current Collectors Using a Pulse Electroplating Method for Fuel Cell Applications

The effect of the Au coated printed circuit board (PCB) as a current collector on the performance of fuel cells is demonstrated. In this study, optimized pulse electroplating was introduced, which was found to be much more effective compared to the direct current (DC) plating for the PCB fabrication based on the passive area from the potentiodynamic polarization scan. Variable electrochemical parameters such as applied potential and frequency for the pulse electroplating method are controlled. Using the polarization tests, the corrosion behavior of the Au coated PCB layer was also observed. From these basic data, the coating methods and electrochemical parameters were systematically controlled to achieve efficient results for direct methanol fuel cells (DMFCs). The stability test for the cell operation indicates that the micro DMFC with the Au coated PCB substrate formed at a frequency of 10 Hz exhibited the highest stability and performance. As a result, the Au coated PCB substrate using pulse electroplating at 1.5 V and 1 kHz can be a promising current collector for portable DMFCs.

Pulse Electroplating of Ni–W Alloy for the Diffusion Barrier in Under Bump Metallurgy

Ni–W alloy was electroplated from citrate bath. The crack-free coatings were obtained using the pulse electroplating method. The surface hardness was increased up to 700 Hv and it is twice as high than that of the electroplated Ni. The surface hardness was increased as the content of W in the coating increased. However, the higher W contents made surface cracks and the surface hardness was decreased. Ni–W alloy made less intermetallic components (IMC) and the shear force of solder ball was increased as much as 20% compared with conventional Ni plating.

Pulse plated Sn-Cu solder coatings from stannate bath

Purpose The purpose of this paper is to investigate the influence of pulse plating current density on the morphology and solderability of Pb-free Sn-Cu solder coatings prepared from alkaline stannate baths. Design/methodology/approach Sn-Cu solder coatings were produced from a plating solution containing sodium stannate, copper stannate, sodium hydroxide and sorbitol additive on copper substrates. The pulse plating experiments were conducted in galvanostatic mode. The plating current density was varied from 5 to 25 mA/cm2, and the morphology of the coatings was studied. The solderability of the coatings was assessed by spread ratio measurement after reflowing the solder coatings at 250°C. Findings The composition control of eutectic solders is always a challenge in plating. The findings show that Sn-Cu coatings prepared by pulse plating are composed of tetragonal ß-Sn structure and Cu6Sn5 compounds irrespective of bath composition and conditions. The final coatings were very dense and smooth with nodular morphology. It was shown that a eutectic composition can be achieved if we apply a current density of ∼15-20 mA/cm2. The solderability studies suggest that solder coatings plated at and beyond 15 mA/cm2 are more suitable for solder finish applications. Originality/value The work presents key issues in pulse electroplating of Sn-Cu solder coatings from an alkaline bath. Possible strategies to control the eutectic Sn-Cu composition by plating process are recommended.

Study on Optimization Technology to Strengthen Ni-Based Composite Coating Electroplate Containing Nanodiamond

Ni-based composite coating containing nanodiamonds was deposited on the substrate of Q235A low-carbon steel in a traditional Watts solution, without any additive. The nanodiamond grains prepared by detonation synthesis were measured by Transmission electron microscope (TEM) and X-ray diffraction (XRD). The electrochemical behavior of Ni2+ ion in the composite bath including nanodiamonds was studied by linear sweep voltammetry experiments, and the morphology, elastic modulus, and hardness of Ni-based composite coating were characterized using Scanning Electron microscope (SEM) and the nano-indenter XP tester. Effects of the nanodiamond concentration in the bath, stirring speed, and the electroplate mode on the properties of Ni-based composite coating were investigated. The results show that the reduction of Ni2+ ion in the electroplating process increased initially, and then decreased as the nanodiamond concentration in the bath increased from 4 g/L to 16 g/L, irrespective of whether direct current (DC), single-pulse, or double-pulse electroplating mode was used. The highest over-potential could be obtained when the nanodiamond concentration in the bath was 8 g/L. Moreover, the hardness and elastic modulus of the composite coating prepared by the DC electroplating mode were 4.68 and 194.30 GPa, respectively. By using the same plating parameters, the coating prepared by the double-pulse electroplating mode showed better properties, with hardness and elastic modulus values of 5.22 and 197.38 GPa, respectively.

Effects of Pulse Electroplating Parameters on Return Loss (S11) and Surface Roughness of Silver Coatings

The highly conductive silver is widely used in the electronics industry, especially in microwave systems [1]. A silver-plated part will reduce loss at the highest microwave frequencies. In addition to this, it will carry extremely high current load. Surface roughness which distorts the propagation of electromagnetic waves is known to affect the uniformity of the current distribution of very good conductive metals such as silver [1]. The effects of duty cycle, frequency and average current density, which are pulsed silver-plating parameters, on the surface quality of coating have been investigated in this study. These effects have been examined by comparing the return loss (S11). S11 comparisons were made according to a reference gold plate. When S11 comparisons have been made, increasing return loss appears with increasing surface roughness. These effects have been characterized by SEM and XRD. [1] Balanis, C. A. (1989). Advanced Engineering Electromagnetics. John Wiley & Son 235th ECS Meeting Session: Industrial Electrochemistry and Electrochemical Engineering Division General Session 1Symposium: F01 - Industrial Electrochemistry and Electrochemical Engineering General SessionTechnical Interest Area: F - Electrochemical EngineeringDay: Wednesday, 29 May 2019

Reversed Pulse Plating of Silver-Cobalt for Connector Applications

The manuscript describes the use of anti-galling silver-cobalt alloy as a novel metallic contact finish for connector applications. The purpose of this work was to develop a cost-effective and cyanide-free and self-lubricated silver-cobalt alloy deposited using reversed pulse electrodeposition process for silver-based contact finishes in electrical contacts applications. The manuscript describes a novel silver-cobalt alloy deposited through reversed pulse-electroplating process that provides exceptionally low friction coefficient (similar to hard gold) and outstanding wear resistance compared to standard silver and any commercially available electroplated silver alloys such as silver-tin, silver palladium, silver antimony, silver-bismuth, silver-tellurium, and silver-tungsten.