OPA2333: OPA2333

HI Marco,

Yes, it is important to clean the PCB board thoroughly after soldering and assembly, and remove any residual solder flux.

Residual flux left on a PCB assembly can manifest itself as unwanted parasitic capacitances and resistances. In particular, high impedance/low current circuits are extremely sensitive to flux contamination. Normal washing or cleaning of PCB assemblies with isopropyl alcohol or deionized water are NOT always sufficient to remove all flux residue.  Flux may get trapped underneath ICs where it can form undesired, parasitic capacitances and resistances.  These parasitic elements are often sensitive to temperature changes and an op amp excessive drift can be erroneously diagnosed due to flux contamination.

On our engineering PCB prototypes, our PCB cleaning procedure requires access to an ultrasonic deionized (DI) water bath:

– Place the EVM in the ultrasonic cleaner and fill with fresh deionized (DI) water.

– Run the ultrasonic cleaner for 20 minutes at 45°C.

– Remove all moisture from PCB.

– When handling the EVM, always hold the board by the edges.

–  When not in use, place the PCB or EVM evaluation board in ESD bag or other enclosure to prevent dust and other contaminants from settling on the board.

Some water soluble fluxes are no longer water soluble once they are mixed with heat and solder so be sure to research what type of flux is being used and how to properly clean it on a final assembly. Consult the respective flux manufacturer or board assembly subcontractor, as proper flux removal may require use of a detergent based wash procedure. 

Thank you and Regards,

Luis

Solder Flux Contamination.pdf

International Conference on Soldering and Reliability ICSR 2016_paper_Why Clean A No-Clean Flux.pdf