Technical Library | 2020-03-09 10:50:17.0
A customer called the Helpline seeking advice for cleaning no-clean fluxes prior to applying a conformal coating. The customer's assemblies were manufactured with a no-clean rosin based solder paste (ROL0) and were cleaned with an isopropyl alcohol (IPA) wash. After cleaning, a white residue was sometimes found in areas with high paste concentrations and was interfering with the adhesion of the conformal coating (Figure 1). For conformal coatings to adhere properly, the printed circuit board (PCB) surface must be clean of fluxes and other residues. In addition, ionic contamination left by flux residues can lead to corrosion and dendrite growth, two common causes of electronic opens and shorts. Other residues can lead to unwanted impedance and physical interference with moving parts.
Technical Library | 2010-09-09 16:44:48.0
The effectiveness of cleaning stencils and misprinted/dirty printed circuit boards can be effectively monitored. This can be done by washing known clean circuit boards and then checking to see if they have stayed clean as a result of the washing process.
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