One "green" solution to board cleaner chemistry is the use of environmentally benign bicarbonate salts, such as potassium bicarbonate, as saponifiers
The use of a saponifier
, steam rinsing with DI water, followed by DI water rinsing did a good job of solubilizing the flux.
Did you talk to the technical representatives from the new saponifier and cleaning equipment suppliers to be sure the process and equipment setup you are using is fine?
Even more pertinent is the possible incompatibility of the new saponifier with your soldermask, flux and perhaps water temperatures.
Since you did not have the problems before the changes, the most probable explanation is that the new saponifier is incompatible with your flux and soldermask or water temperatures.
Cleaning with a saponifier
and steam, with low pressure on the entire assembly, can remove the moisture absorbing flux and even clean fabrication residues that may cause long-term reliability risks.
The boards were cleaned using three different cleaning protocols-water only, saponifier #1 and saponifier #2.
Results showed that saponifier #1 and the water-cleaned only paste left high levels of flux residue on the surface of the board-below the BGA component.
Q: What recommendations would you make to increase the ability to remove residues using saponifier #1?
I recommend using lower pressures in the prewash and wash sections, at a slower belt speed, and evaluation of saponifier #2.
Although it would intuitively seem that aqueous saponifiers
(soap and water) are preferable to semi-aqueous cleaners, the latter have a number of advantages over the former, including avoiding the need for waste treatment or disposal of dirt, saponifiers
and detergents and the possibility of closed-loop recycling, as organic soil dissolves in the cleaning agent.
The product is safe for use with metals, plastics and elastomers that are compatible with water-based organic and inorganic saponifiers