Design007 Magazine

Design007-Nov2018

Issue link: http://iconnect007.uberflip.com/i/1053050

Contents of this Issue

Navigation

Page 62 of 105

NOVEMBER 2018 I DESIGN007 MAGAZINE 63 in the second pass of simulations. Based on the measured dielectric thickness and mea- sured capacitance, the dielectric constant and dielectric loss numbers were also updated. Fig- ure 6 shows the representative cross-section photos, and Table 2 details the nominal and actual simulation parameters. For the open-edge test boards, three different simulators were used: a simple analytical solu- tion based on loss-less cavity models imple- mented in Excel macros [3] , a causal SPICE grid model solved by Berkeley SPICE [1] , and a hybrid solver (Cadence Sigrity PowerSI) [4] . You can see the correlation for the 4-mil lam- inate in open-edge test boards in Figures 7 and 8. The impedance magnitude correlation is quite good. Even the lossless analytical formu- las (black trace labeled "Excel") capture cor- rectly the capacitive downslope, overall induc- tive upslope, as well as the antiresonance peak frequencies. What it cannot capture properly are the loss-related items: magnitudes of the Figure 7: Impedance magnitude correlation of the 4-mil laminate data at the corner (L) and center (R). Table 2: Nominal and actual simulation parameters. Figure 6: Cross-sections of the test board with four different laminate thickness: (L to R) 4, 1, 0.5, and 0.35 mils. Only the upper half of the stackup is shown. The DUT laminate is towards the bottom of the photos.

Articles in this issue

Archives of this issue

view archives of Design007 Magazine - Design007-Nov2018