ISA Standard 71.04: Changes Required for Protection of Today's Process Control Equipment

Corrosion-induced failures remain frequent in electronics products used in industrial environments. The International Society for Automation (ISA) Standard 71.04-1985 provides a classification system using corrosion (or reactivity) monitoring to determine the corrosive potential of an environment towards electronic equipment. Changes to electronic equipment mandated by the European Union directive 2002/95/EC “on the Restriction of the use of certain Hazardous Substances in electrical and electronic equipment” (RoHS) required the elimination of lead in electronic equipment. Recent research has shown that printed circuit boards made using lead-free materials can be more susceptible to corrosion than their tin/lead counterparts. Now even environments previously considered relatively benign concerning electronics corrosion are experiencing serious problems as a direct result of RoHS compliance. With the passage of a number of RoHS regulations and the switch to lead-free finishes on printed circuit boards, many are now questioning whether this type of environmental monitoring is adequate. Reactivity monitoring now needs to provide a more complete environmental assessment than the monitoring techniques described in ISA Standard 71.04. This standard is long overdue for a major revision to address issues described for and since the implementation of RoHS. This paper will discuss changes that have been proposed for the current vision and what changes may be anticipated in future revisions.