What is a key consideration when purchasing a selective solder system for lead-free?

When making the transition to lead-free and making the decision to use selective soldering, it is important to consider the flexibility of the system. You do not want to be “stuck” with a single solution. It is key to have a system that can do both lead and lead-free with no changeover, so dual pots are a must. It is also important to consider what else the machine can do. For example, the JUKI 400 Selective Soldering System can have multiple mini selective soldering waves (at least 4), a full turbulent wave up to 18" and a mini selective stamp module for soldering extremely close to SMD components. These can all be used within the same single machine.

Selective soldering is somewhat of a slow process compared to traditional wave soldering. Is there product that can be used for soldering high-volume/low-mix PCBs?

Selective soldering is generally much slower than traditional inline wave soldering machines. However, this generally is acceptable depending on the need. When it comes to high-volume products, you cannot have cycle times of 3, 5 or even up to 10 minutes for a single panel. So, in this case, there are stamp/dip soldering machines that take between 25 and 65 seconds (depending on configuration). With this type of machine the cycle time is always the same whether soldering one joint or 1,000 joints. There are different ways of doing this but there are preferred methods for safety reasons. First, it is imperative to keep the board completely flat while soldering. The JUKI EMLS, MLS, and LLD type machines keep boards flat during soldering up to tolerance of 0.002". Besides this, it is important to keep a steady, consistent, accurate solder application. JUKI’s high-speed machines use a patented technology that uses no flowing solder, but precisely machined tools that hold the exact amount of solder for the specific joints, components, boards, etc., which helps to reduce bridging and other defects.