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A-Line Heats up Reflow
December 31, 1969 |Estimated reading time: 2 minutes
The Senju nitrogen reflow (SNR) series ovens use high-power, high-efficiency heating methods to minimize ΔT on the most complex board assemblies, while reducing the waste of expensive nitrogen. The company’s ECO-Tronics directive demands that new designs look for any and all ways to reduce the effects of electronics manufacturing on the environment.
By Derek Daily, Senju Comtek
Senju Metal Industry Co, Ltd (SMIC) of Japan is displaying our latest innovations in reflow soldering at the IPC Midwest show in September. The Senju nitrogen reflow (SNR) series ovens use high-power, high-efficiency heating methods to minimize ΔT on the most complex board assemblies, while reducing the waste of expensive nitrogen. SNR ovens also may be optioned with flux collection technologies, using our fume-density control system.
SNR reflow systems include high-power circulation fans in combination with a proprietary flow nozzle design to minimize temperature fluctuation greatly. The heated zones’ nozzle design, in the form of a zig-zag pattern, controls circulation more effectively than previous linear flow designs. Cooler air is returned more rapidly throughout the entire heated chamber area, rather than directed further away to an outer return channel. In this case, the cooler air may be recirculated more rapidly and at a higher velocity. Tunnels typically measure 350 mm in length per zone. The later SNR designs are capable of heated air flow 2.5 to 3× the previous flow rates. Development of these newer systems has reduced ΔT on Senju’s test PCb by an average of 30%. Using 250 mm heater fans and rated to withstand over 10 years of operation even when exceeding typical lead-free temperature ranges, the SNR ovens’ heated zones are robust and efficient.
Senju’s internal ECO-Tronics directive demands that new designs look for any and all ways to reduce the effects of electronics manufacturing on the environment. Senju’s equipment design teams continue to improve flux collection systems and electrical efficiency in all models. Relative electrical current use continues to drop when compared to previous generations of our equipment. For cooling, the SNR systems use a variety of elaborate ducting and condensation filters to remove the greatest amount of exhausted flux fumes. Cooling zones typically are 600-mm long. Senju examined a number of methods to achieve the best collection, including trapping, condensing, and catalyzing the fumes. More than 12 m3/min of suction is achieved with the fume extraction system. Filters also are exchanged easily, allowing cleaning in a short amount of manufacturing downtime. In the end, a new combination of factors has improved greatly upon previous systems, with a 50% increase in the amount of flux fumes being collected.
Nitrogen concentration consistency across all zones remains unaffected by this high-volume fume removal system. The SNR-825, for example, is capable of maintaining less than a 20-ppm difference in O2 concentration from PCB entrance through PCB exit, when running at a low N2 flow rate and with a target O2 concentration of 100 ppm. Low O2 ppm concentration may be reached within 15 minutes of a new profile setting. O2 levels may have preset limits hardwired into the oven upon request. This system ensures the best wetting ability possible during the reflow soldering stage.
SMIC SNR reflow ovens are available worldwide with UL or CE certification. Ovens include 6- to 10-zone heating; 1 to 4 independent cooling zones are available. PCB dimensions of 24" or wider and over 2" in height are accommodated. Visit Senju Comtek’s booth to learn more about the SNR oven and features at the IPC Midwest show.
Derek Daily, GM sales and technical support, Senju Comtek (USA), may be contacted at 20300 Stevens Creek Blvd, Cupertino, Calif 95014; (408) 446-7866; ddaily@senjucomtek.com; www.senju.com.