Life expectancy of Aqueous Flux going LowZ

[edwardtre]

Looking for any life expectancy data for water soluble flux going low Z. How long it takes for conductive material to migrate and cause low impedance bridges at any humidity or temperature.

 

[berkeman]

Looking for any life expectancy data for water soluble flux going low Z. How long it takes for conductive material to migrate and cause low impedance bridges at any humidity or temperature.

Welcome to the PF.

Are you asking specifically just about the flux aspect, or about dendritic migration of copper in general?

I did a Google search on dendritic migration pc board, and got some good hits:

https://www.google.com/search?sourc..._l=hp...0i22i30l5.0.0.1.13565...0.YrpWiZego6U

Once you have a voltage difference between conductors of a couple of volts or so, you can get dendritic migration to happen in a few hundred hours, depending on temperature and PC board cleanliness...

 

[edwardtre]

Thanks for the response. Specifically the conductive material that is part of the flux. Need to consider expected failure rate of a component with water soluble flux (OA) residue left under a BGA (BGA too large to allow for complete removal of flux (45mm part). Though I guess it could be a combination of the flux and exposed copper...

 

[berkeman]

Thanks for the response. Specifically the conductive material that is part of the flux. Need to consider expected failure rate of a component with water soluble flux (OA) residue left under a BGA (BGA too large to allow for complete removal of flux (45mm part). Though I guess it could be a combination of the flux and exposed copper...

It seems like there should be some good PCBA industry studies on this. I Googled bga reliability pcb cleaning, and got some good hits. Maybe have a look at the hit list to see if you see any new information:

https://www.google.com/search?sourc...cleaning&gs_l=hp...0.0.0.9110...0.epKIo8N_xH8