Andrew Nelson

Error in COSMOS Works - poisson's ratio too high

Discussion created by Andrew Nelson on Mar 9, 2009
This is my first time using the COSMOS Works package and I have imported a Solidworks 2008 model of a FR4 substrate with four board components(TSSOP, flip chip, and 2 BGA) with materials fully defined. I have set parameters for a static study of stresses due to thermal boundary conditions of -40 degrees C and 125 degrees C. When I pressed "run", I got an error message saying "Poisson's ratio should be less than 0.5". The problem with this error is that I have gone through all the materials used in this assembly and their properties but the highest poisson's ratio is 0.4 for the Sn63 solder bumps. Has anyone encountered an error like this or knows how to fix it? Thank you.