SMT007 Magazine

SMT-Dec2015

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84 SMT Magazine • December 2015 portantly, its cost, from a benchtop unit han- dling 8" boards (starting in the $10,000 range), up to free-standing machines with capacities up to 24" using a very large solder pot (costing as much as $80,000 or more). The larger sizes will also accommodate much more solder, which also contributes to the cost of ownership. A larger system provides greater flexibility. It can not only handle larger boards, but it can also handle multiple smaller boards conveyed side-by-side to increase throughput. A prospec- tive buyer may consider production throughput by calculating number of boards through a to- tal cycle time from start to finish varying from 2.5–4 minutes from flux to solder. Features of wave solder There are two types of wave: • Laminar wave produces a very smooth laminar flow of solder much like a waterfall. This is the most widely used type. • Turbulent wave sends solder up into the board with a highly turbulent wave used for thru-hole components such as pins with long legs that are fairly closely positioned, and for denser components. The turbulent wave helps to wick off (pull solder from the component's stem into the component joint) excess solder to reduce icicles or bridging. Some machines are available with dual pots that can be used independently or together on the same board. SMD components are often processed in a turbulent wave machine. How a wave system works Based on the machine's control system, a wave is created by a high pressure chamber pushing solder out through the solder noz- zle. A chamber holds the nozzle, pump mo- tor that drives an impeller inside the pressure chamber. The conveyor that holds the board attacks the wave at a 7° angle, and makes contact on sMT QuiCk TiPs SeLecTInG A WAVe SoLDerInG SySTem, PArT 2 Figure 1: Turbulent wave (left) and laminar wave (right) in same system.

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