Showing papers on "Electroplating published in 2008"

The effect of current density on the grain size of electrodeposited nanocrystalline nickel coatings

Abstract: The aim of this work was to investigate the effect of current density on the grain size of electrodeposited nickel coatings. For this purpose, nanocrystalline nickel coatings were deposited from a Watts bath containing 5 g/l sodium saccharin as an additive, by direct current electroplating at different current densities. X-ray diffraction analysis and modified Williamson–Hall relation were used to determine the average grains size of the coatings. The experimental results showed that the coating grains size decreased sharply by increasing the current density from 10 mA/cm 2 to 75 mA/cm 2 . Nanocrystalline nickel coating with average grain size smaller than 30 nm can be achieved at the current densities higher than 50 mA/cm 2 . Furthermore, a general and simple theoretical model based on atomistic theory of electrocrystallization has been made in order to find out the relationship between the grain size and current density. According to this model the variation of log (d) versus log (i) was linear which is in accordance with experimental results for the current densities lower than 75 mA/cm 2 .

Fabrication and actuation of ionic polymer metal composites patterned by combining electroplating with electroless plating

Abstract: The novel fabrication technique that patterns the multiple electrodes of the ionic polymer metal composite actuators was developed to mimic the swimming and flapping locomotion of a living thing. The developed method is to combine electroplating with the electroless chemical reduction using the patterned mask. The advantages of this fabrication method are that the initial compositing between the polymer and platinum particles can be assured by the chemical reduction method, and the thickness of each electrode can be controlled easily and rapidly by electroplating. By using the fabricated actuator with a multiple degree of freedom, the oscillatory and undulatory waves of the flexible membrane actuator was generated and a twisting motion was also realized to verify the possibility of mimicking the fish-like locomotion. Present results show that this novel method combining electroplating with electroless plating can be a promising technique to easily pattern multiple electrodes and to implement the biomimetic motion of the polymer actuators with good mechanical bending performance.

Undercut-free blm process for pb-free and pb-reduced c4

Abstract: A system and method for eliminating undercut when forming a C4 solder bump for BLM (Ball Limiting Metallurgy) and improving the C4 pitch. In the process, a barrier layer metal stack is deposited above a metal pad layer. A top layer of the barrier layer metals (e.g., Cu) is patterned by CMP with a bottom conductive layer of the barrier metal stack removed by etching. The diffusion barrier and C4 solder bump may be formed by electroless plating, in one embodiment, using a maskless technique, or by an electroplating techniques using a patterned mask. This allows the pitch of the C4 solder bumps to be reduced.

Influence of plating parameters and solution chemistry on the voiding propensity at electroplated copper–solder interface

Abstract: Interfacial voiding in solder joints formed with Sn–Ag–Cu solder alloys and electroplated Cu was examined as a function of the plating solution chemistry and parameters. Galvanostatic Cu plating of ~10 μm thick Cu films was performed in a commercially available plating solution, and in model generic plating solutions. Analysis of the current voltage behavior along with Secondary Ion Mass Spectrometry studies of organic impurity content of two plated and a wrought copper samples, yielded a conclusion that for certain chemistry solutions (e.g., H2SO4 + CuSO4 + Cl− + PEG) and current density ranges above 2.5 mA cm−2, organic impurities were incorporated into the growing Cu. Solder joints were produced with a variety of electroplated Cu samples. These joints were, then, annealed at a temperature of 175 °C for 1 week, cross sectioned and examined. In general, it was observed that interfacial voiding in laboratory electroplated Cu layers was qualitatively similar to the unexplained voiding observed in some industrially plated Cu products. More specifically, it was found that the propensity for voiding could be correlated with specific electroplating parameters that in turn were associated with significant incorporation of organic impurities in the Cu deposit.

Electrodeposition of tin: a simple approach

Abstract: Electroplating of tin from acidic plating solutions has been studied for more than one hundred years. The plating solutions contain various additives in addition to stannous ions, which make them complicated and difficult to control. In this work, a simple tin plating solution has been developed. The slightly acidic electrolyte contains only two components: tin (II) chloride and tri-ammonium citrate. It is environmentally benign, easy to prepare, easy to control and electrodeposition can be done at room temperature. Plating rates in excess of 20 μm/h at a current density of 10 mA/cm2 are attainable from solutions with 0.31–0.41 mol/L (75–100 g/L) of tri-ammonium citrate and 0.22 mol/L (50 g/L) of SnCl2·2H2O. The resultant deposits are dense with smooth morphology.

Hydrogen Bubbles and the Growth Morphology of Ramified Zinc by Electrodeposition

Abstract: Real-time X-ray microscopy was used to study the influence of hydrogen-bubble formation on the morphology of ramified zinc electrodeposit. The experimental results show that when intense hydrogen bubbling occurs at high potential, the morphology of the ramified zinc deposit changes from dense-branching to fern-shaped dendrite. The fern-shaped dendrite results in part from the constricted growth due to hydrogen bubbles but also from the highly concentrated electric field. The fern-shaped dendrite morphology was observed during the early stages of electroplating for both the potentiostatic and galvanostatic modes; however, the deposit plated in the galvanostatic mode densified via lateral growth during the later plating stages. This indicates that potentiostatic plating for which the hydrogen-bubble formation steadily occurs throughout the electrodeposition process is better than galvanostatic plating for fabricating fern-shaped deposits, which are ideal electrodes for Zn-air batteries due to the relatively large specific area. (C) 2008 The Electrochemical Society.

High thermal performance packaging for optoelectronics devices

Abstract: A light emitting module comprises a light emitting device (LED) mounted on a high thermal dissipation sub-mount (500), which performs the traditionally function of heat spread and the first part of the heat sinking. The sub-mount is a grown metal that is formed by an electroplating, electroforming, electrodeposition or electroless plating process, thereby minimising thermal resistance at this stage. An electrically insulating and thermally conducting layer (502) is at least partially disposed across the interface between the grown semiconductor layers of the light emitting device (512) and the formed metal layers of the sub-mount (500) to further improve the electrical isolation of the light emitting device from the grown sub- mount. The top surface of the LED is protected from electroplating or electroforming by a wax or polymer or other removable material on a temporary substrate, mould or mandrel, which can be removed after plating, thereby releasing the LED module for subsequent processing.

Process for through silicon via filling

Abstract: A semiconductor electroplating process deposits copper into the through silicon via hole to completely fill the through silicon via in a substantially void free is disclosed. The through silicon via may be more than about 3 micrometers in diameter and more that about 20 micrometers deep. High copper concentration and low acidity electroplating solution is used for deposition copper into the through silicon vias.

Study on the characteristics of Ni–W–P composite coatings containing nano-SiO2 and nano-CeO2 particles

Abstract: The aim of this research work was to co-deposit nano-SiO2 and nano-CeO2 particles into the Ni–W–P alloy coating in order to improve the surface properties further. Ni–W–P–SiO2–CeO2 composite coatings were prepared by co-deposition of nickel, tungsten, phosphorus, nano-SiO2 and nano-CeO2 particles on the surface of 15 steel from the electroplating bath which nano-SiO2 and nano-CeO2 particles were suspended by high speed mechanical stirring. The characteristics of the composite coatings were assessed by micro hardness test, Taber Abrader test, scanning electron microscopy and X-ray diffraction. The results obtained in this study indicate that the nano-SiO2 and nano-CeO2 particles were dispersed evenly within the Ni–W–P alloy coating and the bonding between the matrix metal and nano-SiO2 and nano-CeO2 particles is compact. That the co-deposition of nickel, tungsten, phosphorus, nano-SiO2 and nano-CeO2 particles leads to uniform Ni–W–P–SiO2–CeO2 composite coatings possessing better micro hardness and abrasion resistance properties when heat-treated at 400 °C for 3 h. In addition, that nano-CeO2 and nano-SiO2 particles can increase the thermal stability of Ni–W–P alloy coating at high temperature.

Inkjet printing of passive microwave circuitry

Abstract: Inkjet printing technology was utilized to fabricate transmission lines on a glass substrate. 50 micron resolution was realized using 10 pL drop volumes on a Corning 7740 glass substrate. This can be further improved by applying other methods as described in this paper. The conductivity of the sintered silver structures were 1/6 that of bulk silver after sintering at a temperature much lower than the melting point of bulk silver. A comparison of the DC resistance of the sintered silver shows that it can be a match for electroplated and etched copper. Printed Coplanar lines demonstrated losses of 1.62 dB/cm at 10 GHZ and 2.65 dB/cm at 20 GHz.

Method of Chrome Plating Magnesium and Magnesium Alloys

Abstract: A process for chrome plating magnesium and its alloys. The process uses a combination of electroless nickel plating, a multi-stage copper coating transition system and multiple layers of electrodeposited nickel to form a corrosion resistant system of substantial impermeability and interlayer adherence suitable for direct chromium electroplating.

Fabrication and Optimization of a Nanoporous Platinum Electrode and a Non-enzymatic Glucose Micro-sensor on Silicon.

Abstract: In this paper, optimal conditions for fabrication of nanoporous platinum (Pt) were investigated in order to use it as a sensitive sensing electrode for silicon CMOS integrable non-enzymatic glucose micro-sensor applications. Applied charges, voltages, and temperatures were varied during the electroplating of Pt into the formed nonionic surfactant C16EO8 nano-scaled molds in order to fabricate nanoporous Pt electrodes with large surface roughness factor (RF), uniformity, and reproducibility. The fabricated nanoporous Pt electrodes were characterized using atomic force microscopy (AFM) and electrochemical cyclic voltammograms. Optimal electroplating conditions were determined to be an applied charge of 35 mC/mm2, a voltage of -0.12 V, and a temperature of 25 °C, respectively. The optimized nanoporous Pt electrode had an electrochemical RF of 375 and excellent reproducibility. The optimized nanoporous Pt electrode was applied to fabricate non-enzymatic glucose micro-sensor with three electrode systems. The fabricated sensor had a size of 3 mm x 3 mm, air gap of 10 µm, working electrode (WE) area of 4.4 mm2, and sensitivity of 37.5 µA•L/mmol•cm2. In addition, it showed large detection range from 0.05 to 30 mmolL-1 and stable recovery responsive to the step changes in glucose concentration.

Method and apparatus for producing conductive material

Abstract: A photosensitive film, which has a transparent support and a silver salt emulsion layer containing a silver salt formed thereon, is exposed and developed to form a metallic silver portion. The base material to be plated is electrified in an electrolytic solution free of plating substances, using the metallic silver portion as a cathode. Then, the electrified base material is subjected to an electroless plating treatment to form a first plated layer only on the metallic silver portion. The base material is subjected to an electroplating treatment to form a second plated layer on the first plated layer, further form a third plated layer on the second plated layer.