High Frequency Dk and Df Test Methods Comparison
The high frequency Dk/Df extraction test methods considered can be categorized into three types; Z-Direction, Trace/Conductor, and In-Plane.
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Authored By:
Karl Sauter
Oracle Corporation
Santa Clara, CA
Joe Smetana
Alcatel-Lucent
Plano, TX
Summary
The High Density Packaging (HDP) user group has completed a project to evaluate the majority of viable Dk (Dielectric Constant)/Df (Dissipation Factor) and delay/loss electrical test methods, with a focus on the methods used for speeds above 2 GHz. A comparison of test methods from 1 to 2 GHz through to higher test frequencies 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.
Conclusions
The high frequency Dk/Df extraction test methods considered can be categorized into three types; Z-Direction, Trace/Conductor, and In-Plane. This work has also shown that laminate material supplier data sheet values and higher frequency (above 2 GHz) Dk and Df test method results for the same laminate material can vary significantly. However, this project work found strong correlations between Dk and Df test method results when the same board construction is used and when these test methods are of the same type.
The quick overall trace conductor loss test methods used for ongoing production monitoring are not suitable for evaluating a specific laminate material due to the effects of other complicating factors on overall loss including dielectric thickness, trace width, treatment used, and copper surface roughness.
Initially Published in the IPC Proceedings
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