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Pete Starkey Reports: ICT 40th Annual Symposium

Demë Mulaj of Nelco gave an interesting view on the changing needs of OEM companies and the need for new materials, but for reasons of commercial confidentiality preferred that the details of his presentation were not published.

ICT Chairman Professor Martin Goosey was optimistic that the reporting of his presentation would be free from ironically amusing typographical errors, as he gave an update on the TSB-funded STOWURC project, “Recovery of Copper from PCB Manufacturing Processes using Crab Shells,” describing the development of a sustainable process of using waste products from the seafood industry to recover metals from PCB manufacturing effluent. Chitin, a natural component of the shells of crustaceans, had the ability to adsorb heavy metals from dilute solution, and a simple chemical modification of chitin, by alkaline deacetylation to form chitosan, significantly improved the efficiency of adsorption.

Professor Goosey summarised the results of initial experiments. The effects on adsorption rates of parameters such as temperature, pH, initial concentration, rate of mixing, and specific metal ions had been studied, over a range of chitosan parameters including the amount of adsorbant, the degree of deacetylation, and the particle size. It was possible to reduce copper concentration in effluent to the 0.1 ppm level. Having captured the metal, it was possible to desorb it with sulphuric acid and recover it by straightforward electroplating. A key issue was the residual adsorption efficiency of the chitosan after stripping of copper. There was a tendency for absorption ability to decrease with each cycle, and conditions were being optimised to minimise the effect. There were additional opportunities to optimise the chitosan adsorption process for metals other than copper in the general metal finishing industry, as well as recovering rare metals, including platinum, palladium, rhodium, osmium, iridium, mercury, and gold, from low-concentration solutions.

Specialist in chemical process applications of ultrasound, ICT Deputy Chairman Dr. Andy Cobley reported progress on two collaborative projects: Susonence and Mesmoproc. Susonence was a three-year, multi-partner project aimed at producing industrial scale ultrasonic equipment for sustainable surface modification in metal finishing and printed circuit manufacture. The objectives of the project were to reduce the use of toxic and hazardous chemicals, and at the same time to minimise waste and reduce energy and water consumption.

Initially, two applications for ultrasonic technology in PCB manufacture had been identified: low temperature, reduced strength permanganate desmearing, and persulphate etching, and extensive laboratory work had been carried out. Field trials in an ultrasonic pilot line at Merlin Circuit Technology had demonstrated that a 50% reduction in permanganate concentration, a 10ºC drop in temperature and a 76% reduction in process time could be achieved, with freedom from interconnection defects and hole-wall pullaway. Pilot trials on persulphate etching were due to start second week in June 2014.

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