Ultra-Low-Loss Laminates/Prepregs Target 100-GbE Apps

Isola Group’s latest generation of its Tachyon laminates and prepregs, Tachyon-100G, features a Z-axis coefficient of thermal expansion (CTE) that’s more than 30% lower than its predecessor. As a result, it becomes a superior option when fabricating high-layer-count, 0.8-mm-pitch line cards (with heavy 2-oz. copper inner layers) required to transmit 100 Gigabit Ethernet (100 GbE) at 25 Gbits/s per channel. Tachyon-100G testing, using OEM-specific signal integrity (SI) and thermal reliability test vehicles (TVs), on the IBM SPP SI TV (fabricated by Gold Circuits Electronics) yielded insertion loss of 0.621 dB/in. and 0.464 dB/in. at 12 GHz on the S3 (high-resin content) and SG (low-resin content) striplines, respectively. Effective dissipation factor (Df) of both striplines was 0.0045. Tachyon-100 also was tested on TVs designed to define minimum pitch capabilities for lead-free printed-circuit-board (PCB) assemblies. It passed 6X thermal stress at 288°C and 6X reflow at 260°C on a 24-layer board with four 2-oz. inner layers, 0.8-mm-pitch ball grid arrays (BGAs), and 0.5-mm-pitch thermal vias. Its electrical properties—a 3.0 dielectric constant (Dk) that’s stable between ‒55 and +125°C up to 40 GHz, and a Df of 0.002—suit it for next-generation designs requiring faster backplanes and daughtercards. Spread-glass and reduced-profile VLP-2 copper materials used for the Tachyon-100 mitigate PCB-induced differential skew and improve signal rise times.

ISOLA GROUP S.A R.L