Selective soldering is emerging as a necessary technology for companies that produce circuit boards with a mix of SMT and through-hole components. In the past, the choices for soldering through-hole components have been limited to hand soldering, masked wave soldering, and single/multi tube nozzles for dedicated selective soldering equipment.

The most typical process is hand soldering, which often produces upwards of 1000 defects per million opportunities (DPMO). The defects range from insufficient fill due to varying solder dwell times, to cold solder joints and missed joints. While labor intensive and hampered by defects, hand soldering is the most widely accepted method for soldering the through-hole leads in heavily populated double-sided circuit board assembly.

The EMPF has the OPUS-3 miniature wave selective soldering system from RPS Automation (Figure 5-1). It is a multi-axis Cartesian Robot designed specifically for selectively soldering through-hole and odd-form components into mixed-technology PCBs, molded modules, and other odd-form assemblies without any special tooling. It has a top-side gantry robot that moves the board above the flux and solder for highly controllable precision and flexibility. The system conforms to SMEMA in-line manufacturing standards, is CE labeled, and is ideally suited for applications where the product is manufactured in small or large lot quantities and high product mix.

The board handler is an optional manual load EF or edge-conveyor (In-Line operation) mounted to the robot, expanding between 4"-18" under program control. The PCB is processed through the fluxing and soldering operation with no operator intervention. The robot then delivers the processed PCB back to the operator, or alternatively to the down stream conveyor, completing the cycle.

The solder station features miniature wave Gaussian soldering technology for exceptional keep-away, lead protrusion clearance and thermal-demand capability. The solder pot is lead-free capable and features automatic level sensing, solder make-up, and PID temperature controls (Proportional-Integral-Differential), including independent N2 heating also with PID temperature controls. Solder nozzles are magnetically coupled and can be quickly changed.

The unique and innovative features of the OPUS-3 Selective Soldering System enable the system to solder almost any thermal demand without requiring special tools such as vision, or pre-heating. The exceptional flexibility, performance, and productivity of the OPUS-3 make it a powerful tool to add to your post-reflow production soldering solutions.

The Windows software is easy to learn and very functional. The user builds a script file by selecting the commands required from a menu. When completed, the script file is executed, controlling all motion and processes. Commands are contained in four classes: System, Motor, Inputs, and Outputs.

• System commands include subroutine calls, IF statements, dwells, and repeats.
  
• Motor commands include a variety of commands that initiate or configure motion. The software can logically link up to four axis to produce linear interpolated motion.
  
• The Input and Output sections allow for checking input states, toggling output states, and configuring the names of each I/O point. These names can be user defined depending on the function.

The software can create, teach, and store an unlimited number of location points in the database. The motion commands can then recall these points and move to any one of them. The motors can be put into jog mode for the purpose of checking and teaching points. An unlimited number of script files can be stored on the computer hard disk. I/O and new move commands can be issued while axis are in motion, making the machine ideal for multi-tasking. Alternatively, a scan of the board can be used at your desktop and a file created remotely that can be downloaded into the Opus for executing a selective soldering pattern.

To learn more about the OPUS-3 from RPS Automation or to schedule a demonstration at the EMPF, please contact Ken Friedman, 610.362.1200, extension 279 or via email at kfriedman@aciusa.org.