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82 SMT Magazine • December 2015 by robert Voigt DDM noVASTAR SmT QUIcK TIPS Selecting a Wave Soldering System, Part 2 ColuMn In the last column, we introduced the vari- ous types of through-hole (or thru-hole) solder- ing techniques, which include: 1. Manual 2. Dip 3. Drag 4. Wave 5. Selective While manual soldering is still in practice today, it is usually not found in a production environment because it involves highly skilled and labor intensive work producing very low numbers of boards. Dip and drag were intro- duced many years ago as lower cost alternatives to wave soldering, but have become outdated forms with the advent of more affordable and highly accurate wave systems. Today, wave soldering is the most common and most efficient form of through-hole sol- dering available. It involves a solder pot large enough to handle the width of the largest boards you expect to process. By pumping hot solder through a nozzle in a way that the bot- tom of the board surface encounters the wave caused by the nozzle, the resultant hot solder waterfall creates a single point of contact across all the connection joints on the board, elimi- nating any potential bridging. The system usu- ally integrates a fluxing station, a pre-heat sta- tion, and a wave station in a conveyorized sys- tem, using fingers or pallet-type board mounts. Wave soldering is a time-tested technique, but there are many variations of systems to look for depending on your needs. In all of them, three operations are involved: 1. Applying the flux 2. Applying pre-heat to activate the flux 3. Applying solder The first step in selecting a wave system is to identify the largest board size (length x width) the machine will be expected to process. This will determine the machine size and, just as im-