Polypropylene Pumps Assure Purity and Reliable Production at Hitachi

Although Hitachi has been assembling semiconductor memories and microprocessors in the Las Colinas area of Irving, Texas since 1978, it was not until 1989 that it expanded operations to include their first wafer fabrication capability outside of Japan. The new facility can now provide submicron products fully manufactured in the United States, for use in data communication equipment, office automation equipment, industrial equipment, and home appliances.

 

The Hitatchi commitment to quality is recognized worldwide. The plant at Irving incorporates the most advanced cleanroom designs and the most sophisticated test equipment. The wafer fabrication facility produces superior quality integrated circuits through the maintenance of an ultra-clean environment and the careful selec­tion of dependable equipment to assure continuous production. During the production process, integrated circuits are created by repeating a series of physical and chemical steps, building layer upon layer of micro-thin material on silicon wafers to produce high standard circuitry designs. The process involves the use of severely corrosive materials such as hydrochloric acid, hydro­fluoric acid, and various caustic solutions.

 

Soon after the initial installation, the Hitachi maintenance department reported continuous leakage from the thermoset pumps on the bulk hydrochloric acid storage tanks. The HCl is used for regeneration of mixed beds (de-ionized water) and pH control of the wastewater. The source of the problem was discovered to Although Hitachi has been assembling semiconductor memories and microprocessors in the Las Colinas area of Irving, Texas since 1978, it was not until 1989 that it expanded operations to include their first wafer fabrication capability outside of Japan. The new facility can now provide submicron products fully manufactured in the United States, for use in data communication equipment, office automation equipment, industrial equipment, and home appliances.

 

The Hitatchi commitment to quality is recognized worldwide. The plant at Irving incorporates the most advanced cleanroom designs and the most sophisticated test equipment. The wafer fabrication facility produces superior quality integrated circuits through the maintenance of an ultra-clean environment and the careful selec­tion of dependable equipment to assure continuous production. During the production process, integrated circuits are created by repeating a series of physical and chemical steps, building layer upon layer of micro-thin material on silicon wafers to produce high standard circuitry designs. The process involves the use of severely corrosive materials such as hydrochloric acid, hydro­fluoric acid, and various caustic solutions.

 

Soon after the initial installation, the Hitachi maintenance department reported continuous leakage from the thermoset pumps on the bulk hydrochloric acid storage tanks. The HCl is used for regeneration of mixed beds (de-ionized water) and pH control of the wastewater. The source of the problem was discovered to be a combination of the pump design and the materials of construc­tion. The FRP pumps were deteriorating under the aggressive ser­vice. During the start-up phase, capacity problems were noted with the waste dilute hydrofluoric acid pumps. The original flows were exceeded, and the pumps couldn’t keep up. All of those pumps had been supplied as part of the original equipment installation for the handling and treatment of wastewater.

 

When a thorough review of the pumping systems was completed, the decision was made to replace the thermoset pumps with Vanton heavy duty centrifugal polypropylene pumps. The pump design selected was one which limited all fluid contact to plastic components. Both casing and impeller are molded from polypropylene. The stainless steel shaft of the pump is sheathed in thick-sectioned PVDF (Kynar®) in the fluid contact area.

 

According to Paul W. LeMaire, Jr., Senior Facilities Engineer at Hitachi since installation of the new pumps the leakage and the capacity problems have disappeared. The thermoplastic pumps are completely inert to the hydrochloric and hydrofluoric acids. In addition, routine maintenance has been simplified because the pump design incorporates a wide-open seal area and sliding bearing which extends the selection of seal configuration and avoids misa­lignment problems.