May 2015 • The PCB Design Magazine 45
Figure 10: Il (left) for a 6-inch trace in Fr408hr rTF using supplier data sheet values for Dk, Df and rz.
effective Dk is shown right.
Figure 11: Il (left) for a 6-inch trace in Fr408hr rTF and effective Dk (right).
agonal close-packing of equal sphere (HCPES)
model
[1]
; the center is the square close-pack-
ing of equal sphere (SCPES) model, or Can-
nonball model described in this paper; and the
right hand figure is triangular close-packing of
equal sphere (TCPES) model. All three models
give equal correction factor results as shown
in Figure 14.
PCBDESIGN
References
[1] Simonovich, Bert, "Practical Method for
Modeling Conductor Surface Roughness Using
Close Packing of Equal Spheres," DesignCon
2015 Proceedings, Santa Clara, California, 2015.
[2] Hammerstad, E. Jensen, O., "Accurate
Models for Microstrip Computer-Aided Design,"
Microwave symposium Digest, 1980 IEEE MTT-S
CANNONBALL STACk FOR CONDuCTOR ROuGHNESS MODELING continues
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