Gold-plated capacitor termination meet specialist needs

February 24, 2015 // By Graham Prophet
Capacitor maker Knowles, for its MLC (multi-layer ceramic) brand 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.

Pure tin-plated terminations allow tin whiskers to grow from surfaces and can cause short-circuits and failures. To help eliminate this problem of tin ‘whiskering’ Novacap has developed a gold flash termination for conductive epoxy or gold/indium solder attachment.

Tin whiskers are microscopic single-crystal metal fibers, thinner than a human hair, capable of bridging great distances between leads on 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, Knowles adds, failures that they can cause represent a real danger especially to Hi-Rel applications such as medical implantable devices and military 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. The company is also able to supply other “hard to find” terminations, such as Tin/Lead, which is desired or required for many military applications, where it can still be specified.