Ensure Proper Cleanliness of PCB Assembly Manufacturing
The cleanliness of a PCB has a direct impact on the quality of the final product. It is the foundation of a successful assembly and will determine how long the finished electronic device will work reliably and safely.
As demands for quality and reliability continue to increase, a comprehensive PCB cleaning process has become vital to the success of the manufacturing and assembly processes. A clean surface helps promote adherence of conformal coatings and provides better visibility for inspection and quality control in the pcb board assembly manufacturing industry.
There are several methods that can be used to clean a printed circuit board, but the most effective method depends on the type of contamination and material being cleaned. In general, all types of conductive contaminants need to be removed from the PCB including cutting oils/fluids, biocides, fingerprints and other debris that will slowly cause corrosion spots on the surface over time. Soldering flux residues need to be removed as well, especially those that are uncured (no-clean fluxes).
The most effective method of PCB cleaning is an aqueous bath and rinse cycle. This removes most of the soluble contamination including ionic species, left over flux residues and debris. In some cases, however, manual de-fluxing is required to get rid of the remaining residues or stubborn contaminants that are unable to plasticize in the aqueous wash.
How to Ensure Proper Cleanliness of PCB Assembly Manufacturing
Aside from a thorough washing, one of the most important steps in PCB cleaning is drying the board. This is critical to preventing the re-introduction of moisture, which can lead to poor adhesion and potential failures in the long term.
Whether a PCB is being hand-soldered, soldered by machine or both, it should be completely dry before being moved to another step. This can be achieved by using a compressed air system that is specifically designed for electronics, as the moisture in regular air may damage components or create shorts on the board. It can also be done by using cotton swabs or tweezers to wipe away hard-to-reach areas on the circuit board, such as under components or between tightly spaced traces.
The cleaning process must be repeated as often as necessary to ensure that the PCB is free of contamination before moving on to the next step in the production process. It is a critical part of the PCB assembly process and must be monitored closely by using a data-driven test system that can detect contamination at its earliest stages.
At WORLD electronics, we hand clean virtually all of the PCBs that we produce. This ensures that all parts are contaminant-free before they move to our automated assembly lines, where they will be exposed to many more potential sources of contamination, such as the pick and place equipment, wave soldering machine, AOI machines, first article testers, x-ray inspection and more. With the right contact angle testing system, we can be sure that all components and assemblies are completely clean and ready to be bonded to a conformal coating.