Graham 
I agree with Bev, but to better correlate the issue to  performance. Subject 
the assembly to a non condensing high humidity  biased (functioning) 
environment (40C / 90%RH can work) and functionally  assessment after this exposure and 
then determine which part of the  assembly is having the performance 
problems. This gives a performance parameter  that is compared against the Ion 
Chromatography in specific area  extractions.  This can tell you much  more about the 
residue under an  0201 or in the SMT area next to a hand solder (or selective 
solder) location  that trapped heavy flux but was poorly cleaned.  Averaging 
the total board  is a 10,000 ft view of the PCB cleanliness and process effect 
but  looking at the critical areas of the circuit such as resistor network, 
RF  filter, or capacitor series on critical circuits can tell you how much  
contamination is needed to create a problem or perform well.  If you could  use a 
localized extraction system that assessed the residue effect under  
electrical performance and then analyze the amount of ionic contamination by IC,  this 
would give you an indication if the residue was corrosive or not based on  
some defined criteria.  But to say that a board is clean or dirty by the  general 
ROSE testing is difficult with today's assemblies and chemistries. 
 
Terry Munson
Foresite 
765-457-8095
 
 
In a message dated 2/19/2008 12:37:37 P.M. Eastern Standard Time,  
[log in to unmask] writes:

Hello  TechNet
I'm in a debate with a supplier about the incoming cleanliness of  one of 
their parts, they claim it's squeaky clean and I claim it's as salty as  a bag of 
salt & vinegar potato chips.  Obviously we are both  exaggerating, but one of 
us has a good claim.

They are fending me off  with resistivity measurements made per the manual 
test method IPC-TM-650  2.3.25  - which works in that I don't know how to 
convert it to the "ug  NaCl/in2" equivalent units I'm used to.  Is there a valid  
conversion?  

Sir Doug of Dew, if you reply please do NOT say it  depends...

regards,

Graham Collins
Halifax Production  Engineering
L-3 communications Electronic Systems
(902) 873-2000 ext.  6215



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