China
Africa
Explore chapters and articles related to this topic
First-Level Packaging
Published in Mitel G. Pecht, Rakesh Agarwal, Patrick McCluskey, Terrance Dishongh, Sirus Javadpour, Rahul Mahajan, Electronic Packaging: Materials and Their Properties, 2017
Mitel G. Pecht, Rakesh Agarwal, Patrick McCluskey, Terrance Dishongh, Sirus Javadpour, Rahul Mahajan
Nickel has been widely used in power devices as a substitute for gold in various environments with no significant reliability problems. Nickel can be deposited from electroless boride or sulfamate solutions, with the low-stress films electroplated from sulfamate baths resulting in reliable bonds. Bonding to the die and the terminal is affected by many film-related factors, including surface finish, film hardness, film thickness, film preparation, and surface contamination. Nickel surfaces are prone to oxidation and should be bonded soon after being nickel-plated, chemically cleaned before bonding, and protected by an inert atmosphere (Harman 1989). Phosphide electroless nickel solutions that deposit films containing 6-8% of phosphorus can result in reliability and bondability problems.
Electroless Nickel-Phosphorus Deposits
Published in Fabienne Delaunois, Véronique Vitry, Luiza Bonin, Electroless Nickel Plating, 2019
Suman Kalyan Das, Prasanta Sahoo
Due to inherent advantages of the deposition process, namely uniform thickness, hardness and corrosion resistance, electroless nickel coatings are also used for deposition on complex shapes and large interior surfaces, for replacing expensive stainless steel vessels in some processing industries, for repairing or salvaging nickel-plated machine parts for improving the adhesion of enamels on steel and application in electronic industries as it is easily solderable.
Mass and heat transfer at a corrugated wall of a square stirred tank reactor and possible applications
Published in Experimental Heat Transfer, 2022
A. M. Teamah, S. A. Nosier, G. F. Malash, W. M. El-Maghlany, G. H. Sedahmed, M. H. Abdel-Aziz, A. S. Fathalla
A stirred tank reactor (cell) and an electrical circuit made up the experimental setup (Figures 1a and 1b). The cell was a square tank made of plexiglass with base measurements of 15 × 15 cm and a height of 25 cm. The anode was comprised of five closely spaced stainless steel screens with a mesh number of 20 and a 15 × 15 cm size. The cathode, which had a 45°Corrugation angle and was nickel-plated, was firmly attached to the tank wall. An agitator, consisting of a stainless steel shaft and revolving turbine impeller, was used to stir the tank. In order to prevent current leakage from the motor into the solution, a plastic sleeve was used to connect the motor and shaft together. The shaft was driven by a variable speed motor.
A comparative study between the effect of swirl flow and axial flow on the rate of diffusion controlled corrosion in a double tube heat exchanger
Published in Experimental Heat Transfer, 2022
S. Mustafa, M. H. Abdel-Aziz, G. H. Sedahmed, D. A. El-Gayar
The apparatus, which is shown schematically in Figure 2, consisted of a 27-liter plastic tank, 0.25 horsepower plastic centrifugal pump, and a vertical annular cell. The outer tube of the annulus that acted as an anode was made of stainless steel and has a diameter of 5 cm and a height of 40 cm. The stainless-steel anode was fixed to a circular plastic base via a stainless-steel flange that was bolted to the plastic base; a rubber gasket was placed between the flange and the plastic base to prevent solution leakage. The cathode was made of a nickel-plated copper cylinder of 2.5 cm diameter connected flush to a plastic cylinder of similar diameter. The total height of the anode and the plastic cylinder was 40 cm. Three cathodes with different active heights were used, namely: a cathode with an active length of 7 cm and a plastic part of 33 cm length, a cathode with an active length of 14 cm, and an inactive plastic length of 26 cm, the third cathode had an active length of 21 cm and an inactive plastic length of 19 cm. The cathode that constituted the inner cylinder of the annulus was fixed centrally in position by placing its lower end in a cylindrical cavity machined in the center of the plastic base. The top of the outer tube of the annulus was fitted with a plastic overflow weir. The annulus was fed with the solution by a tangential feed nozzle of 1.2 cm diameter at the lower end of the cell to generate swirl flow.
Zen and electrochemical surface finishing of materials
Published in Transactions of the IMF, 2021
The reduction of silver ions at the copper surface: is balanced by dissolution of copper from the substrate, forming cupric ions in solution: (b) galvanic corrosion at a defect in a noble metal coating on a base substrate, For example, a steel substrate may pit in an acid solution: with adjacent regions of the nickel plated surface supporting hydrogen evolution: The overall cell reaction is: (c) electroless deposition, e.g. nickel deposition from its ions: and oxidation of hypophosphite to orthophosphite ions in the bath: take place at open-circuit, as long as the surface of the workpiece remains autocatalytic, the overall reaction being reduction of nickel ions by hypophosphite ions to deposit nickel with orthophosphite ion and hydrogen ion formation: As indicated in (Figure 7(a)), the workpiece remains at open-circuit and acts as a mixed electrode, supporting both a cathodic and an anodic reaction.