“Initially we purchased the machine to support a project that had a requirement to connect a printed circuit board assembly (PCBA) with a through-hole connector in a recessed plastic enclosure. That design would have been difficult to process using our standard solder wave. However, as we looked at the capabilities this equipment provides we decided to increase the range of projects we use it for,” said Maurice Hellebuyck, Firstronic’s engineering manager. “It solves an issue that many regional electronics manufacturing services (EMS) providers face: dropping demand for mixed technology processing.”
The challenge is the operating cost and limited flexibility of traditional wave solder equipment. Firstronic’s standard wave solder has a 1500 lb. solder bath compared with two 25-lb. solder pots on the selective solder machine. Hellebuyck pointed out that smaller quantities of solder reduce the time and utility consumption needed to bring the solder to the right temperature, and makes cleaning and dross disposal safer and faster. Additionally, the standard wave solder has a 16-foot tunnel that is filled with nitrogen to create an inert atmosphere for better solder joint quality. Comparatively, the selective solder machine uses an air tight collar filled with nitrogen around the point being soldered.
There are also advantages in processing. When going over a traditional wave of solder, the PCBA and components must be oriented with an optimum approach angle to reduce solder bridging. While some wave solder pallets have been designed with circular inserts to allow a great deal of flexibility in angle of approach, that tooling is costly. Selective solder keeps the PCBA stationary and moves the solder pot and nozzle so the process is less constrained by PCBA design. Its pumps shut off instantaneously, so solder is drawn away from the last couple of leads, minimizing the opportunity for bridge creation. Interchangeable nozzles allow variation in the amount of solder deposited and it is fast to program, translating to quick changeovers and minimized rework and touch-up. The dual pot system can be used with two lead-free pots or with a leaded and lead-free pot, depending on requirements. The machine is equipped with vision and the actual solder joint creation process can be viewed on an adjacent monitor. This allows for fast root cause identification if defects develop.
“Wave solder has never been a capacity constraint at Firstronic because many of our PCBAs are SMT-only. From a through-hole perspective, we traditionally see electrolytic capacitors and connectors, but otherwise even mixed technology PCBAs are SMT,” added Hellebuyck. “While we will continue to maintain our traditional wave solder equipment for higher volume requirements, we see value in downsizing our approach to the soldering process on projects with lower volume through-hole requirements. This is just one more way we are looking to work smarter and save our customers money.”