Hi Greg -
     
     I would like to propose an alternative method - rather than use a 
     viscometer to monitor your solderpaste, use the solderball test in 
     ANSIJ-STD-005. I have used both Brookfield and Malcomb viscometers but 
     due to poor reproducibility and repeatability (gauge R&R) have rarely 
     correlated viscometer measurements to production problems. Solderpaste 
     is not a homogeneous material thus measuring its viscosity 
     characteristics is not a simple task. The Malcomb viscometer was a 
     step in the right direction but many of the subjectivity factors still 
     push the gauge R&R values into the unacceptable category. I still use 
     solderpaste viscosity for incoming inspection of solderpaste but would 
     switch in a heartbeat if another method would gain industry/vendor 
     acceptance. I have been using the 005 solderball test successfully in 
     production. The operators like the test better and there is much less 
     subjectivity. Good Luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Solderpaste Viscometers
Author:  [log in to unmask] at ccmgw1
Date:    5/21/97 3:34 PM


     
     
     
     
Hi All,
     
I am currently looking at viscometers for the evaluation of solder pastes. 
Could someone shed some light on what attributes to look for and possibly 
what vendors are offering such products.  Ay this point Malcom Instruments 
is the only vendor I have found with a product specifically geared to 
solder paste.  The model I have been considering is the PCU-203 series 
which has temperature control.  Is temperature control really necessary? 
Any insights or experiences would be helpful.
     
Greg Parke
Manufacturing Process Engineer
Teradyne, Inc.
     
     
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