it is in the formulation.  your vendor should tell you.  e.g. "6 Feb  
2015 ... Kester 186-18, under MIL-F-14256, was QPL approved as Type  
RMA. ... Type RMA flux. This flux possess high thermal stability for  
soldering multi-layer assemblies which require a high preheat  
temperature. Exposure to high preheat temperatures ... The flux  
residue is also moisture and fungus resistant."


On Apr 9, 2018, at 6:03 PM, David Hillman wrote:

> Hi team! Looking for TechNet's sage wisdom. Some folks are familiar  
> with
> this but many electronic modules have a "shall not be a fungus  
> nutrient
> material"  in terms of the components materials, laminate  
> materials, etc. I
> was asked the question if "properly reflowed flux materials are  
> classified
> as non-fungus nutrient supporting". Does anyone have an knowledge/ 
> data on
> properly reflowed flux residue being "non fungus nutrient supporting"?
>
> TIA
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]