Characterization, Prevention and Removal of Particulate Matter on Printed Circuit Boards

摘要

Particulate matter contamination is known to become wet and therefore ionically conductive and corrosive if the humidity in the environment rises above the deliquescence relative humidity (DRH) of the particulate matter. In wet condition, particulate matter can electrically bridge closely spaced features on printed circuit boards (PCBs), leading to their electrical failure. Failures attributed to particulate matter have even been observed in data centers where the gaseous contamination levels are low enough to meet the ANSI/ISA-71.04-2013 G1 severity level. The combination of miniaturization of electronic components, the reduction of feature spacing on PCBs and the loosening of the data center temperature and humidity envelope to save energy is making electronic hardware more prone to failure due to particulate matter. The characterization of particulate matter on PCBs is challenging because of the small amount of particulate matter available for analysis. The objective of this paper is to develop and describe a practical, routine means of measuring the DRH of minute quantities of particulate matter (1 mg or less) found on PCBs. Data center particle filtration schemes and means of removing the particulate matter from PCBs will also be presented.