Gold flash termination introduced to eliminate tin whiskering

Knowles Novacap has expanded its termination offerings to now include gold-plated terminations. Conventional termination is normally tin/lead, but lead has been banned by the RoHS directive. However, pure tin-plated terminations can allow tin whiskers to grow from surfaces and can cause electrical short-circuits and failures. To help eliminate this problem of tin 'whiskering' the company has developed a gold-flash termination for conductive epoxy or gold/indium solder attachment for its high-performance MLC capacitors. Tin whiskers are microscopic single-crystal metal fibres, thinner than a human hair, capable of bridging great distances between leads on electronic components, and creating short-circuits and failures. They are caused by deposit stress, such as heat, to pure tin plated components and are almost invisible to the eye, needing magnification and special lighting to be seen. However, failures that they can cause represent a clear and present danger especially to Hi-Rel applications such as medical implantable devices and defence equipment. Novacap's gold termination consists of a 5 micro-inch minimum gold flash over a nickel barrier and is defined by the use of a NG in the part number ordering code. It can be specified for both their PME and high-capacitance BME product lines. To further strengthen the company's' commitment to alternate termination offerings other 'hard to find' terminations, such as tin/lead can still be specified, says the company.