CORROSION OF PARTS USED FOR MICROELECTRON ICS APPLICATIONS

Manifestations of corrosion on parts used in microelectronics occur fo r different reasons and are frequently described in literature. They a re not only caused by operational circumstances but are also favoured by the production process. Investigations have been carried out to asc ertain the cause of the failure of several circuit boards used in the operation electronics of the preparation unit for kitchen waste water. During microscopic and electromicroscopic observations of failed circ uit boards, different corrosion types have been found, mainly on the s urface of a commonly used Sn-Pb-alloy. Hence, potentiostatic and free- corrosion experiments under laboratory conditions have been performed using the employed Sn-Pb-alloy. In order to simulate the increased con centration of harmful substances at the surface of the boards, the med ium used contained a high percentage of the substances found in the su rroundings of the unit. From the measured values of current density fo r different potentials and the observed corrosion on the sample's surf ace; conclusions as to the reported failure of the electrical operatio n system have been made. During the experiments under laboratory condi tions, manifestations of corrosion similar to those found on the surfa ce of the failed circuit boards have been observed. Based on these res ults, it seems likely that pitting and selective corrosion of the Sn-P b-alloy led to the failure of the investigated circuit boards and, the refore, of the operation electronics.