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86 SMT Magazine • December 2015 Spray flux is contained in a high-pressure chamber which eliminates evaporation or deg- radation. However, spray systems are much more expensive, they're difficult to set up, and require daily maintenance. They also involve a higher learning curve because it needs to be customized for each different board configura- tion. Preheat systems Flux requires activation by heating, so any wave system requires a preheat station enclosed in a conveyorized chamber, where preheat tem- peratures reach 140°C–175°C. Both the compo- robert Voigt is vp of global sales at DDM novastar inc. To reach voigt, click here. sMT QuiCk TiPs SeLecTInG A WAVe SoLDerInG SySTem, PArT 2 nents and the board are pre-heated to eliminate thermal shock during the wave. Typical preheat technologies are: • Infrared (IR), which produces very robust heat • Convection, which applies more even heating Many preheaters are available with a com- bination. Convection is typically used in a no- clean flux environment, which provides a dry surface and eliminates post-solder cleaning. There are many variables in every system, so it's very important to discuss your needs with a vendor partner to determine what's best for your situation. check references Remember to consult a variety of machine providers, talk to the manufacturers themselves if possible, and get references to contact before making a purchase. An important consideration for a complex machine such as a wave soldering system is factory support, specifically training, software, upgrades and spare parts. Next time: Board handling methods. SmT Figure 4: Spray fluxer. Figure 5: Example of preheaters in a wave solder system.