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
References
[1]
B. Valdez, M. Schorr, M. Quintero et al., “Corrosion and scaling at Cerro Prieto geothermal field,” Anti-Corrosion Methods and Materials, vol. 56, no. 1, pp. 28–34, 2009.
[2]
L. Veleva, B. Valdez, G. Lopez, L. Vargas, and J. Flores, “Atmospheric corrosion of electro-electronics metals in urban desert simulated indoor environment,” Corrosion Engineering Science and Technology, vol. 43, no. 2, pp. 149–155, 2008.
[3]
J. F. Flores and S. B. Valdez, “Cabina de simulación de corrosion para la industria electrónica en interior,” Ingenieros, vol. 6, no. 21, 2003 (Spanish).
[4]
ASTM, “Standard practice for conducting atmospheric corrosion test on metals,” ASTM G50-76, ASTM, West Conshohocken, Pa, USA, 2003.
[5]
G. Lopez, B. Valdez, and M. Schorr, “Spectroscopy analysis of corrosion in the electronics industry influenced by Santa Ana Winds in marine environments of Mexico,” in Indoor and Outdoor Air Pollution, INTECH, 2011.
[6]
“Corrosion of metals and alloys. Classification of low corrosivity of indoor atmospheres: determination and estimation attack in indoor atmospheres,” ISO 11844-1, ISO, Geneva, Switzerland, 2005.
[7]
“Corrosion of metals and alloys. Classification of low corrosivity of indoor atmospheres: determination and estimation of indoor corrosivity,” ISO 11844-2, ISO, Geneva, Switzerland, 2006.
[8]
A. Moncmanova, Environmental Deterioration of Materials, WIT Press, 2007.
[9]
L. B. Gustavo, Caracterización de la corrosión en materiales metálicos de la industria electrónica en Mexicali, B.C. [Tesis de doctorado], UABC, Instituto de Ingeniería, Mexicali, México, 2008.
[10]
G. López, H. Tiznado, G. Soto, W. de la Cruz, B. Valdez, and R. M. Schorr Zlatev, “Corrosión de dispositivos electrónicos por contaminación atmosférica en interiores de plantas de ambientes áridos y marinos,” Revista Nova Scientia, vol. 3, no. 1, 2010.
[11]
G. López, H. Tiznado, G. S. Herrera et al., “Use of AES in corrosion of copper connectors of electronic devices and equipments in arid and marine environments,” Anti-Corrosion Methods and Materials, vol. 58, no. 6, pp. 331–336, 2011.
[12]
M. Reid, J. Punch, C. Ryan et al., “Microstructural development of copper sulfide on copper exposed to humid H2S,” Journal of the Electrochemical Society, vol. 154, no. 4, pp. C209–C214, 2007.
[13]
B. Valdez, M. Schorr, R. Zlatev et al., “Corrosion control in industry,” in Environment and Industrial Corrosion, Practical and Theoretical Aspects, INTECH, 2012.
[14]
S. B. Valdez, W. M. Schorr, B. G. Lopez et al., “H2S pollution and its effect on corrosion of electronic components,” in Air Quality-New Perspective, INTECH, 2012.
[15]
B. G. Lopez, S. B. Valdez, W. M. Schorr, and G. C. Navarro, “Microscopy and spectroscopy of MEMS used in the electronic industry of Baja California region Mexico,” in Air Quality-New Perspective, INTECH, 2012.
[16]
B. G. Lopez, S. B. Valdez, K. R. Zlatev, P. J. Flores, B. M. Carrillo, and W. M. Schorr, “Corrosion of metals at indoor conditions in the electronics manufacturing industry,” Anti-Corrosion Methods and Materials, vol. 54, no. 6, pp. 354–359, 2007.
[17]
J. Smith, Z. Qin, F. King, L. Werme, and D. W. Shoesmith, “Sulfide film formation on copper under electrochemical and natural corrosion conditions,” Corrosion, vol. 63, no. 2, pp. 135–144, 2007.
[18]
K. Demirkan, G. E. Derkits Jr., D. A. Fleming et al., “Corrosion of Cu under highly corrosive environments,” Journal of the Electrochemical Society, vol. 157, no. 1, pp. C30–C35, 2010.