Protection against corrosion of wire bonds in different environment by glob topping

High reliability in electronics has to be guaranteed at worse environmental conditions. At the same time the tendency to smaller dimensions holds an. Under these circumstances the protection against corrosion plays an importa nt role. Methods of accelerated testing are presented for COB devices under glob top. The degradation mechanisms under the influence of temperature an d humidity are investigated. There are always different mechanisms superimp osing. Galvanic corrosion and crevice corrosion is only working at high hum idity levels and the existence of free ions. High temperature leads to the formation of intermetallics. Thermal shock is connected with mechanical str ess. Both may initiate the formation of cracks. It can be stated that as a result of a careful selection of materials and technology a sufficient reli ability level is reached.