Sherman,
       I posted a similar question several months ago concerning heat 
sealing
and other solderability storage issues.  Of the responses I rec'd, no one
provided a reason or information source that stated why heat sealing should 
not be used today.
       I know it has been avoided in the past.  Some of that came from older 

military requirements based on the theory that the trapped gases created 
during the sealing process promoted tin oxidation.  Since the plastic bag 
chemistry has changed in recent years, this may no longer be a concern. 
 Some component manufacturers are now shipping solderable components in heat 
sealed bags.

                           Norm Dill
                           [log in to unmask]

 ----------
From: TechNet-request
To: technet
Cc: xxx{REMOTE/REMOTESUN/BGERPHE}%MSMAIL.Trimble
Subject: ASSY: Packaging
Date: Thursday, July 18, 1996 7:04AM

Our shipping folks insist on packaging board level assemblies in static
shielding bags and HEAT SEALING them.

As I recall several years ago I heard that heat sealing plastic bags for
PCBs at the board level was bad. Seems as if some vapors were deposited
on the fab decreasing the solderability.

Does anyone know of a reason to require that these bags be taped shut and
not heat sealed???

Thanks in advance

Sherman Banks
[log in to unmask]




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