Autumn in the Tees Valley, and a sharp change in the weather after a mild October brought down the leaves in great drifts. Overlooking the river, the Devonport Hotel in the village of Middleton One Row, to the east of Darlington, County Durham in the north-east of England, was venue for the Institute of Circuit Technology's Darlington Evening Seminar on November 3, 2009. An enthusiastic audience, and speakers from as far afield as Japan, Germany, Scotland and Cumbria, gathered to share the latest knowledge on high-speed laminates and advanced conductor finishes.

First to speak was Andreas Gross, from Umicore Galvanotechnic in Germany, with a presentation on multifunctional electroless nickel-palladium-gold finishes for soldering and wire-bonding applications. Comparing alternative processes based on either immersion palladium or electroless palladium as the barrier layer between nickel and gold, he demonstrated that even a very thin palladium layer was effective in maintaining solderability after ageing by preventing nickel diffusion to the surface.

Because of its neutral operating pH, electroless palladium chemistry was less corrosive of the nickel interface than its acidic immersion counterpart during the deposition process. However, except in conditions of extreme thermal stress, electroless nickel immersion palladium immersion gold was a cost-effective and easy-to-operate multifunctional finish which had been customer-approved for mass production in Europe.

Examining in detail the technology of the electroless palladium process, Hiroshi Otake, from Uyemura in Japan, described an innovation which had overcome some limitations of traditional chemistry and offered significant improvements in uniformity of deposition rate, bath stability and adhesion of palladium to nickel. Uyemura had developed an additive which stabilised the palladium chelate and substantially reduced the decline of deposition rate with time. Bath stability was improved, especially at extreme conditions of bath loading. A notable characteristic of the modified chemistry was its ability to promote good adhesion of the palladium deposit even if the electroless nickel surface had deliberately been allowed to oxidise between process stages.

George Wheadon, European Technical Service Specialist for Park Electrochemical, gave the first of the two laminate presentations, introducing a newly-developed low-loss material, branded Mercurywave 9350, which offered a cost-effective alternative to PTFE for radio frequency and microwave applications. Using fine-weave E-glass fabric and a 66% ratio of oxide-filled resin, loss tangent had been reduced to 0.004 at a dielectric constant of 3.5. No special facilities were required to process and fabricate the material.