High Fequency Measurements Paper Published at APEX 2015


The High Density Packaging (HDP) user group has completed a project to evaluate the majority of viable Dk (Dielectric Constant)/Df (Dissipation Factor) electrical test methods, with a focus on the methods used for speeds above 2.0 GHz. A comparison of test methods at common through to higher frequency ranges was desired, testing a variety of laminate materials (standard volume production with UL approval, low loss, and "halogen-free" laminate materials). Variations in the test board material resin content/construction and copper foil surface roughness/type were minimized.

 Problems with Dk and Df test methods and discrepancies in results are identified, as well as possible correlations or relationships among higher speed Dk & Df test methods.

 An example of present difficulties with the variety of test methods used for the same laminate material: a) Cavity resonator method at 10 GHz: Df = 0.008

b) SPP Df test data at 6 GHz:   Df = 0.006 to 0.0075

c) IPC TM, 2-20 GHz Stripline, Panasonic Method   
(3 layer stripline TV, 2x1078 dielectrics ~65% RC, 0.15 mm core):
E-Glass Foil Type P using E-glass: Df = 0.003 to 0.006
Foil Type P using NE-Glass:  Df = 0.002 to 0.005
Foil Type R using E-Glass:  Df = 0.004 to 0.007
Foil Type R using NE-Glass:  Df = 0.003 to 0.006

d) IPC TM-650,, Laminator published data sheet [1 GHz, 54% RC]: Df = 0.002

The above shows a range of Df from 0.002 to 0.008 depending upon the test method and frequency used.  Dk measurement methods have similar disparities.