Dispense Valve

Nordson EFD has developed a non-contact dispense valve for precision jetting of low viscosity flux onto solar cell bus bars. Operating at speeds up to 500Hz/sec, the Square WaveTM 745NC valve meets the photovoltaic industry's need to deposit continuous lines of microdots on the solder-coated metal ribbons that connect adjoining PV wafers. Flux removes oxidation and contamination to improve solar cell efficiency and power output. The valve's solenoid technology delivers a high-speed cycle rate that minimizes process variation for repeatable dot-to-dot consistency. A low actuation speed of 2 milliseconds prevents build-up of flux crystals on the valve's nozzle which could prevent the fluid from being deposited precisely on the bus bar. The pistons' material reduces friction and wear. Tests showed over 880 million cycles of use without any deterioration. Because of its non-contact design, the product never touches the delicate and brittle PV wafer; therefore, breakage and rejects are minimized. A special nozzle enables multiple orifice diameters from 100 - 175 microns so deposit sizes and volumes can be easily changed.