|      Hi!
|      
|      Accelerated aging factor for a new PCB surface finish? 
| Do you mean 
|      oxidation? Intermetallic growth? What type of finish? 
| Please send 
|      additional detailed info covering your request.
|      
|      
|      
|      Dave Hillman

Hi Dave, 

In this case the new PCB suface finish is electroless Ni/immersion Au. And 
you are right, it is oxidation - under extreme and/or even normal storage 
condition, Ni has the tendency to diffuse through Au layer (if there is 
any porosity) and gets oxidized on the top of Au layer, then the 
solderability will be affected due to the existance of nickel oxide on the 
top of Au layer.  

So far I have not found any mathimatical model (either physical or 
experimental)for acceralated aging factor as the function of time in aging 
chamber, temperature in aging chamber, and relative humidity level in 
aging chamber, although I have found several aging method.  But none of 
them provide corresponding aging factor.  By aging factor, I mean the 
ratio between the time in chamber and the time in normal storage 
environment, with same level of solderability degradation.

Thanks in advance for your advice.


Nora 

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