EOS from soldering irons connected to faulty 120VAC receptacles

Certain types of 120 VAC receptacles used in circuit card assembly production areas were discovered to have intermittently faulty grounding contacts. These receptacles have been in use in a number of facilities and are likely to be found throughout the industry. Soldering irons connected to a faulty ground can impart EOS to devices being assembled, and failures have been clearly identified to have been caused by exposure to open-grounded irons. This paper reports on work we have done to 1) determine the receptacle problem, 2) measure and model the EOS, and 3) assess device susceptibility and damage risk.