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The purpose of this paper is to present the results from work on a project aimed at evaluating six different copper alloy substrates coated with pure tin for tin whisker growth. The influence of intermetallic growth between the copper alloy substrate and the tin‐plating on the growth of tin whiskers has been investigated.

The experiment consisted of six substrates of different alloys of copper, plated with bright tin including copper beryllium, cartridge brass, phosphor bronze, Cu‐Ni‐Si “7025” and Cu‐Ni‐Sn “spinodal”. The samples were mechanically stressed and then subjected to temperature humidity storage conditions for 1,000 h. These samples were then evaluated for tin whisker growth and intermetallic layer thickness.

Of the six samples five showed tin whisker growth. For these samples the intermetallic layer thickness has little effect on tin whisker growth. Sample with Cu‐Ni‐Sn “spinodal” alloy substrate showed very low whisker density and comparatively lower maximum whisker length than the other tested substrate material.

More samples per condition should be evaluated to bolster the conclusions. For the sample without tin whisker growth, holes on the surface of the plating were observed. The holes in the plating provide an opportunity for stress relaxation after the plating process. Since stress in the plating layer is low, tin whiskers are not formed on the sample surface.

The paper details the tin whisker growth on six tin plated copper substrate samples. The intermetallic layer thickness for each copper alloy substrate is calculated. The relationship between the intermetallic layer thickness and tin whisker growth for the six substrates are discussed.

To permit multilayer ceramic capacitors to be soldered directly onto printed circuit boards and other components, the terminations are plated with a barrier layer (usually nickel) followed by either pure tin or a tin‐lead alloy. Pertinent properties of deposits and solutions are discussed and these include deposit thickness requirements, internal stress, solderability, effects of cross‐contamination, variations of tin‐lead composition with operating parameters and effluent treatment.

Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM printing technology cannot manufacture the mechanical parts that fully meet the requirements of high precision and strength. This paper aims to explore a new post-processing method for SLM 316L specimen, namely, using of the TiN/TiAlN multilayer coating fabricated by multi-arc ion plating on the surface of SLM specimens, for improving the performance of SLM specimens. The other purpose of this paper is compared the performances of the TiAlN/TiN multilayer coating machined specimen and the TiN/TiAlN multilayer coating SLM specimen.

The TiN/TiAlN multilayer coating is fabricated by multi-arc ion plating on the surface of 316L specimens. The surface morphology and selected mechanical properties of TiN/TiAlN multilayer coating plating on the SLM substrate specimen and the machined substrate specimen were studied in this paper. The analyzed properties included surface topography, micro hardness, the adhesion, the thickness and the wear resistance of TiN/TiAlN multilayer coating plating on the SLM substrate specimen and the machined substrate specimen.

The electron microscope images reveal that surface morphology of TiN/TiAlN multilayer coating plating on the SLM specimens is relatively flat, and there are some micro-particles in different sizes and pin holes dispersed on them. After TiN/TiAlN multilayer coating, the performances of SLM samples, such as micro hardness, the thickness and the wear resistance, were significantly improved. The micro hardness of TiN/TiAlN multilayer coating machined specimen is higher than that of TiN/TiAlN multilayer coating SLM specimen. However, the adhesion of TiN/TiAlN multilayer coating machined specimen is less than that of TiN/TiAlN multilayer coating SLM specimen.

The study provides a new post-processing method for SLM 316L specimen to improve the performance of SLM specimens and to enable SLM specimens to be applied in the field of precision mechanical transmission.

A novel tin electrodeposition chemistry and process has been developed at Bell Laboratories, Lucent Technologies, New Jersey, USA. This process produces smooth, satin bright tin deposits which have stable, large grain structures. The deposits contain very low organic content and, as a consequence, exhibit excellent ductility, solderability and reflowability. The chemistry is capable of operating at elevated temperatures over a wide range of current densities, and is, thus, applicable to rack, barrel and reel‐to‐reel operations. All chemical components, including breakdown products are fully analyzable with conventional analytical methods. Extensive bath life studies show that the deposit appearance and material properties, including grain structures, are stable in relation to the age of the electroplating chemistry. In addition, the grain refiners used are highly stable, and have few breakdown products as the chemistry ages. All these features imply a robust process which has been confirmed in various manufacturing environments. This tin electroplating process has been utilized in plating coatings for connectors, solder bumps, PWBs and components for semiconductor applications.

Tin and tin/zinc plating is used to protect many copper, brass, and mild steel components of electrical switchgear, and to improve solderability. A new automatic plant is used by Yorkshire Switchgear Ltd.

The technological development and characteristics of an innovative process and composition for immersion plating and fusing of a solderable tin/lead deposit over copper are discussed. The process offers a viable alternative to hot air solder levelling, electrodeposition/selective stripping, or inhibitor coatings for maintaining solderability of printed wiring boards. A flat, uniform solderable tin/lead coating on all feature surfaces and edges is achieved. A number of important benefits are derived. The ability to coat any copper surface uniformly, including fine pitch features, is substantially enhanced. Solderability is improved because of a thick, flat, co‐planar and uniform tin/lead deposit on all copper surfaces. Typical thickness and composition of the fused alloy are 150 to 300 microinches (4 to 8 microns) and 65 to 75% tin.

The corrosion resistance of tin‐cadmium alloys, together with a novel method of applying coatings, is leading to new outlets for tin in the automotive industry. Engineers in this industry are adopting light‐weight metal construction wherever possible in an effort to reduce fuel consumption and hence diminish pollution levels. Aluminium has successfully replaced steel in many non‐structural applications such as the wing, wheel housings trim and door sills, but there have been problems in finding suitable fastener materials. Zinc‐coated steel fasteners lack durability and there is danger of bimetallic corrosion between steel and aluminium once the zinc coating has worn. In many cases this problem has been overcome by using tin‐cadmium coatings, which have a longer life and have minimal electrolytic corrosion action with aluminium. The coatings are being regularly used by major automotive manufacturers in the USA and are applied by a mechanical plating technique.

This paper aims to present the results of a 32-year-old laboratory study of whisker growth from tin electrodeposits that was originally undertaken to gain an increased understanding of the phenomenon of tin whisker growth.

Whisker growth was evaluated using electroplated C-rings (both stressed and un-stressed) that were stored throughout in a desiccator at room temperature. Analysis has recently been undertaken to evaluate whisker growth and intermetallic growth after 32 years of storage. Scanning electron microscopy analysis has been performed to investigate whisker length and, using polished cross-sections, the morphology, thickness and type of intermetallic formation.

Normal tin-plated deposits on brass and steel with a copper barrier layer nucleated whiskers within five months, and in each case, these grew to lengths between 1 and 4.5 mm. For normal tin electroplated onto brass, a one- or two-month nucleation period was needed before whiskers developed. They reached a maximum length of about 1.5 mm after six months, and little or no further growth occurred during the subsequent 32 years. Very few whiskers grew on the tin-plated steel samples and no intermetallic formation was observed. None of the fused tin plating samples nucleated whiskers during the 32-year period.

Knowledge about vintage whiskers is important to take steps to increase the resiliency of space missions. Similarly, such knowledge is important to engineers engaged in products reaching their nominal end-of-life, but where, for reasons of economy, these products cannot be replaced.

This study represents a unique insight into whisker growth and intermetallic formation over an extremely long time period.

The use of lead in electronics assembly operations has come under scrutiny due to health and environmental concerns associated with lead exposure. Lead is one of the most useful metals in modern industry; however, lead has the dubious distinction of being one of the most toxic of metals. Increasingly restrictive government regulations on the use of lead are hastening the search for feasible alternatives to tin‐lead solder alloys. From an electronics assembly standpoint, there is a desire to replace lead bearing HASL (hot air solder levelling) coatings with a metallic, lead‐free alternative. To answer these needs, Motorola have developed a lead‐free, immersion plating technology for the surface finish of PCB printed circuit board bond pads. The Motorola development work has focused on the metallurgical system of tin‐bismuth, which is a simple eutectic system similar to that of tin‐lead, featuring a minimal number of phases and a wide operating window.

The increase in printed wiring boards exhibiting de‐wetting characteristics after the fusing of electroplated tin/lead coatings prompted this investigation. Although it became clear during the course of the investigation that the development of the resist was a contributing factor to de‐wetting, it was shown that the sulphate ion concentration of the final rinse before tin/lead plating was the major cause of de‐wetting.