Delta’s Integrated Automation Solution Increases the Yield Rate of PCB Soldering

 Printed circuit boards (PCB) have long been essential for modern electronic equipment. For automation products such as inverters and controllers, PCBs are at the core of control, drive, communications, and many other functions. The quality of PCBs is critical for the performance and stability of equipment.



Common ways of making PCBs include the process of surface mount technology (SMT) or wave soldering. SMT is often used for smaller and more complicated products, while wave soldering has been extensively applied in the production of industrial products. Processed through the wave soldering method, the PCBs are first applied with spray flux and preheated to avoid thermal shock, which may cause warping and other defects associated with a sudden rise in temperature. The PCBs then are sent to the soldering pot, where the machine will activate the advection wave or turbulence, creating an effect that makes the liquid tin stay still or move like boiling water. As the PCBs pass through, liquid tin is soldered to it.



Throughout the processes, the control of temperature during pre-heating section is extremely important as it could influence the evaporation of the flux. If not fully evaporated, the flux will cause pseudo soldering, which means that the internals of the boards will not be connected. Another decisive requirement for successful soldering is the inclination angle of the conveyors. Precise inclination ensures proper contact of the PCBs with the liquid tin surface to avoid excess solder.

Delta’s factories in Central and Southern China have recently applied Delta’s own automation products for an integrated controlling, processing and visualized monitoring system of wave soldering in response to the needs of factory digitalization. The solution adopts the Compact Modular Mid-range PLC AS Series as the host controller to simultaneously perform temperature, motion and wave control. The Standard Temperature Controller DTA Series controls the temperature of preheating section precisely to ensure proper processing.



When the Photoelectric Sensor detects that the PCB is sent for soldering, the inverter will automatically activate the waves of liquid tin. Users can use the Human Machine Interface DOP Series to easily configure parameters according to different PCB types, such as temperature or the speed of the conveyor. All of the data from field equipment is uploaded to the quality management system for real-time monitoring.



The integrated solution brings the following benefits for factories:

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    Automated process to economize material cost: The start and stop of the preheating section and the pot are scheduled according to the runtime of the soldering equipment. The inverter does not activate the waves of liquid tin until the photoelectric sensor detects that the PCBs are to be soldered. This mechanism helps reduce the waste of liquid tin caused by oxidization.
    
    
    
    Reduced anomalies and defects by real time equipment monitoring: Through the communication functions of the HMI DOP-100 Series, key parameters are automatically uploaded to the management system for real time monitoring. It allows better control of equipment status and lifespan, minimizing the time for maintenance. For example, the system monitors parameters such as the temperature curve, soldering voltage and current. If anomalies are found, users are alerted, and the data is recorded, which can effectively avoid losses caused by defective batches.
    
    
    
    Reduced time for parameter adjustment: Delta's barcode scanners are applied to acquire processing information of all PCBs. Through barcode scanning, the controller identifies each PCB and acquires the processing information from the management system. This allows the system to adjust parameters or change recipes accordingly to ensure correct processing. 
    
    
    
    This integrated solution minimizes the chance of material waste caused by oxidization and soldering failure by improper temperature and inclination angle. Additionally, the processing status can be monitored in real time to avoid defective batches, effectively increasing the yield rate of PCB soldering.