A Pennsylvania based circuit board manufacturer uses Electronics Grade Water to wash and rinse their finished product prior to final testing, packaging and shipping. The use of ASTM Type E-2 Water with a resistivity of greater than 17.5 megohms/cm2 and a total organic carbon (TOC) content of less than 50 ppb provides this customer with excellent results.
The feedwater to the Electronics Grade Water System comes from an on-site well. The raw well water first passes through an ultraviolet disinfection unit for a 99.9% inactivation of water borne bacteria. Following is a 1.0 micron absolute filter then an alternating duplex water softening system designed to remove calcium and magnesium hardness from the water for protection of the reverse osmosis membranes. The reverse osmosis unit removes approximately 98-99% of the dissolved mineral salts from the water enroute to a 300 gallon sanitary storage tank. A stainless steel multistage pump directs the water through another (2) deionizers in a series arrangement, through another 254nm ultraviolet disinfection unit and through a 0.1 micron absolute final filter just prior to being distributed to the wash / rinse line.
Since installation of the system in 2016, the measured rejection rate of product has decreased from a high of 20% to a low of 4.5%. Naturally the higher yield of successful boards reduces rework and increases the customer’s profitability.