Fred Fenner originally posted some questions about this subject 12/15/95. 
Mike Frederickson here at the EMPF gave this initial response, and went 
looking for additional info. He was finally able to discuss this with Alpha 
Metals today, and they indicated that they have a good knowledge of the 
subject, and are very willing to discuss at depth. Contact Andy Maki 
(Mackey?) at Alpha 201.434.6778.
 ----------
From: Frederickson, Mike D.
To: Crawford, John A.
Subject: RE: FWD: Air entrapment in pastes
Date:  18 Dec 95 11:17AM

He's looking for specifications or test methods.  I'm unsure of any for this 
type of concern.  From a mechanistic viewpoint, entrapped air will provide 
more available Oxygen that will alter the flux-powder interface which can 
and will have an impact of the solderability of the powder and the rheology. 
 This effect of entrapped air is measureable electrochemically - not so sure 
on the resolution of a viscometer.  From a practical viewpoint, as the paste 
is being worked on the printer, there is little room for static air pockets 
to exist.  In manufacturing, paste is mixed sufficiently such that the 
probability of air pocket survival is small.  I guess the only real concern 
is the possibility of entrapped air in the process of packing the syringes - 
which is highly possible.  From my understanding, this is a manual task -- 
which would increase the level of inconsistency from syringe to syringe. 
 Given that entrapped air has a finite amount of available oxygen, I believe 
that the impact is minimal.  I will call Alpha and get their viewpoint.
 -------------------------------------
SUBJECT: Air entrapment in pastes
MESS-ID: 951215234606(u)100760.351(u)GHV136-1(a)CompuServe.COM
DATE: 1995-12-15 19:30:09
FROM: [log in to unmask]@PMDF@MBIN01
TO: [log in to unmask]@PMDF@MBIN01

sender: [log in to unmask]
From: Mike Fenner, BSP
100760,[log in to unmask]
Fax: +441 295 720 937

For a project: I would be interested to hear from anyone who has knowledge 
of
specifications/procedures for determining the maximum amount of entrapped 
air
in pastes (solder, adhesives or otherwise) as supplied and methods for 
measuring
same. I am concerned with all aspects, eg possible effects on rheology of 
beaten
in air/gas, as well as gross bubbles in syringes. Alternatively suggestions 
for
measuring techniques and max limits for "packaged air" particularly  would 
be
welcome.