This was scaring, Doug,
one guy here, Lars Ryen at SES (Space Div of Ericsson) found huge amounts of
outbleeding stuff from different plastic bags. Sometimes as much as a micron
thick film. His conclusion was that one should be cautious with all plastic
material if clean surfaces are hot topics. I would like to connect you two
together for judging our bags, let's see what Mr Ryen likes that. Thanks for
your very encouraging message, I can now add one more issue to my already
heavy burden. He-he.
Ingemar
PS. Bev's companion?

-----Original Message-----
From: Douglas Pauls [mailto:[log in to unmask]]
Sent: den 30 januari 2001 18:59
To: [log in to unmask]
Subject: Re: [TN] Pink ESD Bags


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

----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET
Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------