Hi,

 Will you help me to answer the following question:

 Our company produce payment-transaction products, to ensure the quality we
 sampleing test its PCBA (print circuit board assembly) ionic contamination
 useing OMEGA METER 600-SMD before final assemble. While wanting to define
 the acceptance limit (unit: ug.NaCl/sq.in. the general is 14.0), we
 encounter the problem: how to calculate its total surface? In my opinion:
 Total surface area=level factor*2*bare board surface.

 Reason:

 1. high density of component of PCBA can enlarges its "contamination
    surface", then times "level factor".
 2. components lie on the both sides of PCB, then times "2".

 FYI--my company's PCBA manufactureing process:

 PCB side A print solder paste----->Side B through wave soldering.

 Although we have four volumes of IPC Standards and Specifications, I can't
 find the clear definition about PCBA ionic contamination test, especially
 how to calculate the total surface. Will you help to direct the information
 or offer your opinions?

 Thanks with best regards,
 Huckl Chang.

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