Hello TechNet...
Years ago, there was an industry problem with pink polypropylene ESD bags
causing a degradation of solderability.  Does this problem still exist?
Should we accept components packaged by our distributors in these bags?

*The original problem with the bags was that it used polyethylene with an
open cell structure, soaked with a topical antistatic material.  The
function of that antistatic material was to attract moisture from the air,
thereby forming a "sweat layer" on the bag surface, thereby providing the
ESD protection.  As that material continually migrated to the surface, it
was eventually used up.  Old pink poly bags were no better than normal poly
bags at that point.  From the solderability standpoint, the migratory
agents, which were generally amines, interfered with soldering.  From a
contamination standpoint, amines are electrically conductive and
represented a contamination threat.

In response to this problem, the pink poly bag manufacturers changed the
formulation such that the antistatic agent was bonded into the polymeric
structure of the bag, theoretically eliminating the migratory nature of the
material.  It still had the same mechanism of attracting moisture from the
air to provide the sweat layer, so the pink poly still did not work well in
dry climates.  I have not seen contamination from these newer style of
bags, but I consider the ESD protection to be highly suspect.  From a
cleanliness standpoint, the smoky-gray metalized ESD bags are clean and
don't have humidity dependence.  Yes, I know they are more expensive, but
worth it, IMNSHO (in my not so humble opinion).

Should you accept parts in these bags?  Depends.  How comfortable are you
with the risk?  I would suggest that you take some virgin pink poly
material.  Extract it overnight at room temperature using deionized water.
Do the same thing for parts stored in the bags.  Compare the two extracts
using FTIR.  If you don't get any of the pink poly signature materials on
the parts, then you have answered your question.

Doug Pauls
Rockwelll Collins

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