Upgrading your existing wave soldering machine with an external spray fluxer, new preheat modules, solder pot retrofit kit and titanium solder pot liner significantly reduces the cost of converting to lead-free wave soldering. This is actually true when applying an upgrade strategy to a used wave machine. It provides effective lead-free performance at a fraction of the cost of a new piece of equipment. Upgrading not only reduces capital outlay, but also reduces your lead-time, since upgrades can be added in less time then the delivery and installation of a new machine. An additional benefit is that operators will have a shorter learning curve resulting in a smoother transition to implementing lead free wave soldering.



Implementing lead-free wave soldering involves more than replacing one solder alloy with another because no ?drop-in? replacement strategy exists. A common notion is that one can simply switch from tin-lead (SnPb) to lead-free by dropping lead-free solder into an existing wave machine. Another general misunderstanding is that you need to buy a new wave machine for lead-free processing. Neither of these tactics is correct because there are alternative ways to minimize the cost of implementing lead-free wave soldering. For lead-free wave soldering to be successful in a production environment, necessary changes to the entire process must be considered. The majority of lead-free solder alloys possess good solder ability but exhibit decreased wetting characteristics compared to tin lead solders. Since wetting is a critical factor affected by solder temperature, contact time, flux, use of nitrogen and wave configuration, changes are required that will affect the majority of machine parameters.

Introducing lead-free wave soldering generally involves two major process changes because lead-free alloys have a significantly higher tin content than tin lead solder and require higher processing temperatures. Many products will be converted to lead-free over a gradual phase-in; however, numerous manufacturers are forging ahead by making their wave soldering machines lead-free compatible now.

Process Parameters

Because the wetting characteristics of lead free alloys tend to be less than tin-lead solder, using good flux chemistry is critical. Additionally, the higher temperatures needed for lead-free soldering require a flux chemistry that can withstand preheat temperatures up to 130'C and liquid us solder temperatures as high as 280'C for up to 3 seconds. VOC-free, water-based flux is generally recommended since they meet these higher temperature requirements. Often an existing wave solder machine may need upgrading with a newer spray fluxer to be suitable for processing VOC, water-based fluxes. An ultrasonic or nozzle type spray fluxer works best since the flux droplet size can be controlled and a continuous and uniform spray pattern can be applied across the entire PCB. This is essential since it is important to achieve the smallest possible droplet size with VOC-free fluxes to obtain good through whole penetration.