Abstract
Liquid crystalline polymers (LCPs) are a relatively new class of polymers with excellent high temperature properties. They are being considered for electronic packaging applications, such as molded multichip modules, where high dimensional tolerances are critical for component operation. High stresses and temperatures can be generated in molded leadframes during surface mount soldering operations and component service. Under these conditions, time dependent deformation or creep could result in warpage and failure of molded leadframes. In order to aid designers in estimating component lifetimes, the creep properties of Xydar G930 were investigated. Xydar G930 is a LCP with 30 wt.% glass filler. A series of short term (24 h) uniaxial creep tests were conducted at several temperatures and stress levels ranging from room temperature to 350°F, and 0.3 UTS to 0.8 UTS, respectively. Values of steady state creep rate were calculated from the creep curves and fit to an Arrhenius analog as a function of temperature and a power law relation as a function of stress. Results showed linear viscoelastic behavior at low stresses and significant dependence of creep on temperature and stress.
