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Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70‐95°C to give a suitable deposition rate. This is becoming problematic in industry due to the rising price of energy and is a major contribution to production costs. Previous studies have noted beneficial effects of ultrasonic irradiation upon electroless plating processes and it has been reported that sonication can increase the plating rate and produce changes to the chemical and physical properties of the deposited coating. The purpose of this paper is to reduce the operating temperature of an electroless nickel bath by introducing ultrasound to the process.

The deposition rate of an electroless nickel solution was determined by two techniques. In the first method, test coupons were plated in an electroless nickel solution at temperatures ranging from 50‐90°C and the plating rate was calculated by weight gain. In the second approach the mixed potential (and hence the current density at the mixed potential) was determined by electrochemical analysis of the anodic and cathodic reactions. In both cases the plating rate was found with and without the application of an ultrasonic field (20 kHz). The electroless nickel deposits obtained in the plating tests were also analysed to determine the phosphorus content, microhardness and brightness.

The plating rates under ultrasonic agitation were always higher than under “silent” conditions. Most importantly, considering the objectives of this study, the deposition rate under sonication at 70°C was significantly higher than that found with mechanical agitation at 90°C. In addition, the results indicated that the deposits produced in an ultrasonic field had consistently lower phosphorus content, higher microhardness and were brighter than those prepared in an electroless nickel bath that was not sonicated.

Although previous work has been performed on the effect of ultrasound on electroless plating, all these studies have been carried out at the normal operating temperature of the electroless process. In this paper, ultrasound has been applied at temperatures well below those normally used in electroless nickel deposition to determine whether sonication can enable low temperature electroless plating.

This paper aims to investigate the layer of material deposited on a sample of acrylic resin by electroless nickel plating process. Acrylic resin is a popular material in rapid prototyping (RP) which uses the additive manufacturing technique to build prototypes for visual inspection, assembly, etc. Metallization of the RP materials can extend application envelop of RP techniques, as they can be used in decorative or functional applications.

Unlike electroless nickel plating on a metal substrate, the plating process for an acrylic resin substrate is different, as there is no metal ion for the auto-catalytic electroless reaction. Pre-treatment processes are performed on an acrylic resin sample to initiate electroless nickel plating. The morphology, chemical composition and structure of the layer deposited on the sample are examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction.

The investigation shows that a nickel phosphorous alloy layer is plated on to the substrate surface of the acrylic resin sample.

Plating a layer of nickel phosphorous alloy layer on an acrylic resin RP material can widen the application of RP technology. An application of nickel plated acrylic resin sample to rapid tooling for low-volume production plastic parts is presented.

Trials have been performed to assess the practicability of the electroless nickel plating method applied to textile fabrics with various fabric constructions including polyester woven fabrics and polyester meshes. The effect of electroless nickel plating on different polyester fabric constructions had been studied. The results displayed that the nickel could be successfully plated on various fabric structures. In this study, it was found that fabric constructions can influence the appearance of electroless nickel-plated fabrics and generate different metallic effects. Fabric structure is considered to be a very important factor for determining the desired appearances of electroless nickel-plated fabrics. Moreover, electroless nickel plating is able to simulate the metallic effects of hard metal products on non-conductive fabrics with soft handle. Such findings could give inspiration to designers to design fabrics with different brilliant textures.

Austenitic stainless steels (ASS) have inadequate resistance to stress corrosion cracking (SCC). There are several ways to minimise the risk of SCC. One method is to increase the nickel content of the ASS. Electroless and electroplated costings were applied to ASS, Type 304, in order to produce a thin layer of nickel on its surface. Also during the present study, a SCC test was carried out at constant load in a tensile‐testing machine. The results showed that a thin layer of austenitic phase that had a high concentration of nickel and chromium was produced. This layer had good corrosion resistance compared to that of the base material and contained lower concentrations of Cr and Ni. The results obtained in these experiments reveal that austenitic steel to which the electroless coating process had been applied showed improved resistance to SCC, due to the presence of precipitates of the hard phase, Ni₃P, which retarded localised breakdown of the oxide film.

A problem exists with electroless nickel/immersion gold (E.Ni/I.Au) board surface finish on some pads, on some boards, that causes the solder joint to separate from the nickel surface, causing an open circuit. The solder joint cracks and separates when put under stress or when it experiences a shock. An ITRI (Interconnect Technology Research Institute) project to investigate this E.Ni/I.Au problem was initiated about a year‐and‐a‐half ago. Since the electroless nickel/immersion gold board finish performs satisfactorily most of the time, a 24 variable experiment was developed to investigate which parts of the chemical matrix are satisfactory to use and which need to be avoided. This paper describes some of the activities that have occurred on the ITRI consortium, from the design of the test vehicle to building hundreds of BGA assemblies, then pulling those BGA assemblies apart and inspecting the results.

Studies immersion gold over electroless nickel, immersion gold over electroless palladium, immersion gold over electroless palladium over electroless nickel, immersion gold over immersion silver and immersion silver. In the palladium finishes, two palladium thicknesses were evaluated: 10‐12μin. and 18‐20μin. Multiple plating chemistry suppliers provided plated test vehicles. HASL and OSP test vehicles were included as control samples. In total, 14 finishes were evaluated in the test matrix. The test vehicle was a daisy chain of zero ohm 1,206 chip resistors that could be monitored individually. Test vehicles were assembled using 63Sn/37Pb eutectic solder paste on an automated assembly line. The thermal cycle range was ‐40°C to 125°C with 30‐minute transition times and 15 minutes at each extreme in a single chamber air system. For each test matrix cell, 120 zero ohm resistors (40 from three boards) were continuously monitored for electrical failure (>100ohms). In addition, resistors were sheared from test vehicles and the shear force at failure was recorded. A decrease in shear force did occur with thermal cycling due to crack initiation and growth in the solder joints. Solder joint cracks have also been examined.

The aim of this paper is to detail the changes needed to ensure compatibility of printed‐circuit board (PCB) surface finishes with the use of lead‐free solders and in lead‐free assembly processes.

The paper describes the various popular solderable surface finishes that are currently available. It then reviews them in terms of the required adaptations necessary to meet the requirements of the Restriction of Hazardous Substance (RoHS) Directive and to ensure compliance, whilst meeting the performance needs of the product.

Some of the available and popular finishes, such as organic solderability preservatives and tin require modifications while, others including silver, direct immersion gold and electroless nickel immersion gold are transitioning well into the world of lead‐free. Electroless nickel, electroless palladium, immersion gold is one finish that performs better with lead‐free assembly than it did with conventional eutectic solder‐based approaches.

The paper provides a concise overview of the implications for specific surface finishes when making choices for use with lead‐free and RoHS compliant PCB soldering and assembly.

The paper aims to use aluminium alloy to substitute steel as the main material of ultra-precision hydro-static bearing system for an ultra-precision plastic electronics production system to lower the manufacturing cost. The total cost of diamond turning and nickel-based electroless coating of an aluminium alloy bearing is expected to be less than the cost of manufacturing a stainless steel bearing.

The paper used a large amount of theoretical calculation to obtain optimal specifications of the bearing system. ANSYS modelling was selected to simulate the deflection of the bearing shaft under high oil pressure. Hundreds of measurements were conducted after the bearing had been manufactured.

The paper provides industrial application insights on using aluminium alloy with a high-quality nickle-based electroless coating as a successful substitution of stainless steel. This created a more economic hydro-static bearing system.

Because of the time limit, different rotational speed tests shall be conducted in the future.

The paper provides implications for the application of nickel-based electroless coating to improve the surface property and bending strength of aluminium alloy, as well as classifying ultra-precision diamond turning as an economic finishing process.

This paper has identified the importance of aluminium alloy with a nickel-based electroless coating as the substitution of stainless steel in a precision hydro-static bearing system.

This paper describes the tests performed to evaluate the solder capillary action which occurs within a gap between two solderable surfaces during soldering. The goal was to determine the optimal gap distance for maximum capillary flow in the attainment of hermetic solder joints capable of withstanding extreme temperature cycles and various mechanical shocks. One of the test conditions was arranged so that the gap thicknesses would vary while the width of the gaps remained constant. In a second condition, the gap thicknesses remained constant while the gap widths varied. Three plating designs were evaluated. They were nickel plating; nickel overplated with gold; and nickel, copper intermediate, with tin overplate. The capillary action of all three plating combinations deposited onto aluminium specimens, with the gap configurations previously described, was evaluated. The capillary results were measured with X‐ray and microstructural data. End use solder joint designs were determined from the capillary results. These designs are shown and they include the best plating design for the application. In addition, an unexpected result was obtained that is useful for testing the solderability of all finishes—the Configured Capillary Solderability Test.

Printed circuit boards (PCBs) requiring component attachment, whether leaded or surface mount technology, must have the exposed copper land areas coated with a protective finish. This protective coating must not inhibit solderability and at the same time must act as a barrier for preventing the copper from oxidizing and the inevitable assembly problems that would ensue for the end‐user. Globally, the predominant surface finish in the PCB industry is hot air solder levelling (HASL). Driven by the adoption of solder mask over bare copper, HASL was developed as a reliable method of applying solder to the copper surfaces after solder mask. During HASL, a thin layer of solder is deposited onto the exposed copper by passing the boards through a hot, molten wave (or pot) of solder and subsequently blowing the excess solder from the boards using high velocity hot air. This process has been increasingly under scrutiny due to environmental and safety issues (hazardous waste, lead exposure, etc.), technological limitations (fine‐pitch device assembly) and equipment maintenance cost. This paper reviews the major alternative surface finishes being currently deployed and additionally seeks to give an overall assessment of the broader environmental aspects of such finishes.