Circuits Assembly - September 2008 - (Page 56)

Equipment Advances SEHO’s Go Soldering Line T he GoReflow 1.8 and GoReflow 2.3 automatic reflow soldering ovens have five and seven heating zones, respectively, and heating zone lengths of 72.8" and 92.5", respectively, and are suited for small-to-medium-sized production. Designed for soldering in ambient atmosphere, the systems afford a high volume of circulated process gas, generated with axial fans, and adapted slot nozzles to ensure homogeneous heat distribution over the complete transport width. The heat transfer rate to the assemblies permits lower oven set temperatures. To reduce maintenance, a flux management system with stainless steel filter is integrated in the peak and cooling area. Flux residues are collected in a PE bottle, making disposal easy and environmentally friendly. Conveyor options include belt, chain with or without center-board support, or a combination of belt and chain. Comes with upto-date control unit for quick programming and may be integrated into a fully automated production line. The GoSelective light selective soldering machine is compact and designed for standalone operation with manual infeed and outfeed of assemblies. During the process, the assembly remains on its position, while the workstations (fluxer unit, preheater and soldering unit, which are mounted on a high-precision axis system), successively approach the solder joints. This permits flexible processing of assemblies up to 500 x 500 mm with reproducible results. Features a micro drop jet fluxer said to precisely define volumes, thus permitting a defined spray pattern with minimum overspray. Processes all conventional flux types. The preheat area comes with halogen emitters to support solvent evaporation and board preheat. Designed for miniwave soldering processes, with a variety of quick-change solder nozzles, suitable for dip and drag soldering processes. Nozzle options include coated, said to be nearly maintenance-free, and uncoated, for processing extremely small grid spacings. Comes with local nitrogen inertion, control unit and a high-precision axis control. Features fiducial recognition and correction function. Programming requires only the x and y coordinates of the components to be soldered to be entered and filed. An online teach system with camera is optional. Available from SEHO, seho.de. n Figure 1. The GoReflow oven includes process gas cleaning with environment-friendly solution to dispose of condensates. Figure 2. The GoSelective light’s micro drop jet fluxer precisely defines volumes and minimizes overspray. Continued from pg. 55 By using the AS22 column of Dionex and modifying the eluent to get great separation, we have solved the co-elution problems from the AS4A-SC and AS18 columns on sulfate and all the WOA, and sulfate from bromide. By using ROSE testing on a production floor, large changes can be seen and investigated. Periodically we have seen high ROSE readings, but as a general rule, boards pass with good ROSE readings. By looking at localized pockets of contamination on the assembly in critical circuit areas and entrapment locations, we can control a cleaning or selective wave soldering process. It is the pocket of contamination causing leakage and corrosion problems in the field and during ESS testing, so a process controlled with tools designed to look at contamination in different areas provides the best understanding of process and residue effects. n 56 Circuits Assembly SEPTEMBER 2008 circuitsassembly.com http://seho.de http://circuitsassembly.com

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Circuits Assembly - September 2008 Contents Caveat Lector Industry News Market Watch Talking Heads Focus on Business Global Sourcing On the Forefront Screen Printing Better Manufacturing Reflow Soldering with a SnCu Eutectic Pb-Free Alloy Improving OEE in High Mix Facilities Effectively Managing RF Design in Utility Metering Applications Solder Joint Reliability of Different BGAs Reworked Using Low Melting Point Pb-Free Alloys Tech Tips Wave Soldering Pb-Free Lessons Learned Materials World Process Doctor Equipment Advances Product Spotlight Ad Index Assembly Insider Technical Abstracts

Circuits Assembly - September 2008

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