%0 Journal Article
%T Copper Corrosion by Atmospheric Pollutants in the Electronics Industry
%A Benjamin Valdez Salas
%A Michael Schorr Wiener
%A Roumen Zlatev Koytchev
%A Gustavo L¨®pez Badilla
%A Rogelio Ramos Irigoyen
%A Monica Carrillo Beltr¨¢n
%A Nicola Radnev Nedev
%A Mario Curiel Alvarez
%A Navor Rosas Gonzalez
%A Jose Mar¨ªa Bastidas Rull
%J ISRN Corrosion
%D 2013
%R 10.1155/2013/846405
%X Hydrogen sulphide (H2S) is considered one of the most corrosive atmospheric pollutants. It is a weak, diprotic, reducing acid, readily soluble in water and dispersed into the air by winds when emitted from natural, industrial, and anthropogenic sources. It is a pollutant with a high level of toxicity impairing human health and the environment quality. It attacks copper forming thin films of metallic sulphides or dendrite whiskers, which are cathodic to the metal substrate, enhancing corrosion. H2S is actively involved in microbially influenced corrosion (MIC) which develops in water, involving sulphur based bacteria, in oxidizing and reducing chemical reactions. H2S is found in concentrated geothermal brines, in the atmosphere of geothermal fields, and in municipal sewage systems. Other active atmospheric pollutants include SOX, NOX, and CO. This investigation reports on the effects of H2S on copper in microelectronic components of equipment and devices, with the formation of nonconductive films that lead to electrical failures. 1. Introduction The electronics industry is spread out worldwide; it is an important sector in the Mexican economy, representing 80% of industrial companies in the northwest of the country. Their assembly plants are located in three cities: Mexicali, an arid zone, Tijuana, an urban-industrial area, and Ensenada, a marine region on the Pacific Ocean coast, all belonging to the State of Baja California, near the Mexico-USA border. The electronics industry appeared in Mexico during the sixties with the manufacture of electronic products such as radios, audio record and play devices, and televisions. This industry designs and manufactures microelectronic components called microcontrol devices (MCD), integrated with microelectromechanical systems (MEMS). A study was conducted in the indoor areas of three electronics plants in these cities. Copper and its alloys are widely applied in the electric energy, electronics, and semiconductor industries because of their high electrical and thermal conductivity, ductility, and malleability. Copper is considered a noble metal; it resists attack by oxygen, although some air pollutants, such as H2S, change its surface properties, even at ambient temperature, forming a thin layer having completely different properties compared with the pure metal surface. This layer lowers catastrophically the adhesion of the soldering alloy or conductive resins and paste, provoking failures of the printed circuit board (PCB) of the microelectronic devices. Compounds such as geerite (Cu8S5) are formed on Cu in the
%U http://www.hindawi.com/journals/isrn.corrosion/2013/846405/