Contaminants Affecting PCB Life, and Cleaning Recommendations

Contaminants Affecting PCB Life, and Cleaning Recommendations
 
The IPC lists several contaminants that can affect PCB performance and longevity. According to IPC, the following contaminants must be removed from circuit boards using cleaning techniques that are safe for workers and environmentally sustainable.
 Polar residues - etch materials, flux components, chemicals in substrates, etc.
 
 Non-polar water-soluble residues - welding oils and waxes
Non-polar water-insoluble residues - SMT adhesives, synthetic resins, greases and mold release agents.
Insoluble Residues - Silica and clay type fillers and glass fibers in laminates.
No reflow solder paste
Reflow Flux Residue
 Uncured (wet) SMT adhesive
IPC Cleaning Residue Recommendations
Consider the following when cleaning PCBs.
Make sure to clean both sides of the PCB. This is important, especially when using spray air to clean the system.
Clean the system with a spray air equipped with a filter. This helps to remove fine particles from the cleaning solution, thereby improving the quality of the cleaning process.
 When cleaning internal electrical components, be sure to maintain the correct flush pressure and duration for a thorough cleaning.
 Throughout the cleaning process, the PCB must be properly positioned and properly secured. This allows for a smoother cleaning process without damaging the PCB components due to any vibration or shock.
 Cleaning systems using ultrasonic technology must have ultrasonic frequencies of 40 kHz or higher to ensure effective cleaning.
 Make sure there is no adhesive residue in the pads or vias. Vias are one of those hard-to-reach places that must be cleaned carefully.
Debris can hinder PCB operational excellence and efficiency. Also, the mess of the PCB will lead to its failure in the near future. Therefore, the IPC strongly emphasizes the need to clean the PCB without damaging it in the process. You can use manual or benchtop cleaning, ultrasonic and batch immersion cleaning, and air jet cleaning methods. However, the choice of cleaning process must depend on the type of PCB material, the assembly process used, and the type of components being mounted.