Isola introduces ultra-low-loss materials for 100-Gigabit Ethernet applications



Isola Group, a market leader in copper-clad laminates and dielectric prepreg materials used to fabricate advanced multilayer printed circuit boards (PCBs), announced the introduction of Tachyon-100G laminates and prepregs, which enable line cards required to transmit 100 Gigabit Ethernet (100GbE) at data rates in excess of 25 Gb/s per channel. Tachyon-100G has identical electrical properties as its predecessor Tachyon; however, the Z-axis coefficient of thermal expansion (CTE) on Tachyon-100G is more than 30% lower than Tachyon, making it more suitable for fabricating high-layer count, 0.8 mm pitch line cards with heavy 2 oz. copper inner layers.

The increasing demand for feature-rich applications and faster access to computing, HDTV, video conferencing, video on demand and digital photography have propelled the need for 100GbE enterprise solutions in data centers and carrier networks around the world. Isola has begun alpha site testing on Tachyon-100G using OEM-specific signal integrity (SI) and thermal reliability test vehicles (TVs).

For example, on the IBM SPP SI TV, fabricated at Gold Circuits Electronics (GCE), insertion loss measurements yielded 0.621 dB/in. (0.245 dB/cm) and 0.464 dB/in. (0.183 dB/cm) at 12 GHz on the S3 (high-resin content) and S6 (low-resin content) striplines. The results for the S3 and S6 were 37% and 43%, respectively, better than Panasonic’s Megtron 6 with HVLP copper. The effective dissipation factor (Df) of 0.0045 on both stripline structures was best in class on the SPP SI test vehicle and the results for the S3 and S6 were 72% and 92%, respectively, better than Megtron 6. Tachyon-100G has also performed reliably on TVs designed to define minimum pitch capabilities for lead-free PCB assembly. For example, it has passed 6X thermal stress (TS) at 288°C and 6X reflow at 260°C on a 24-layer board with four, 2 oz. inner layers and 0.8 mm pitch BGAs and 0.5 mm pitch thermal vias.

Michael Griffin, Chief Technology Officer at Gold Circuit Electronics (GCE) stated, “Tachyon-100G will provide us exactly what we need in this space, as most of the OEMs are looking for a 25-30% improvement over MEG 6, a material which may no longer be able to satisfy future high-speed digital requirements. Tachyon-100G also has processing advantages that will allow us greater freedom to use it efficiently in our PCB manufacturing process.”

Isola is also announcing the successful completion of the beta testing of Tachyon, which was engineered for high-speed digital backplane designs that have data rates in excess of 25 Gb/s. Multiple industry standard SI and thermal TVs have been built successfully with Tachyon.

Tachyon Field Testing Highlights:
Tachyon was used successfully to build multiple homogenous and hybrid high-layer count backplanes:
36-layer 24” X 36” x 0.300” that passed 6X TS at 288°C and 6X at 260°C reflow
36-layer 18+18 sequential laminated backplane
28-layer 16”x18” x 0.300” backplane
34-layer 24” x 21” x 0.280” hybrid backplane with four 4/4 oz. copper cores of 370HR.
36-layer 24” X 28” 0.247” backplane with four 3/3 oz. copper cores

Tachyon was successful on a number of signal integrity TVs:
Speeding Edge 16-layer TV: Tachyon had an insertion loss of 0.849 dB/in. at 16 GHz on a 0.004” wide line that was 8” long line. This is 35% better loss than Panasonic's Megtron-6 with HVLP copper on the same TV.
Storage OEM’s internal serpentine SI TV – Tachyon had an insertion loss of 0.621 dB/in. at 12.5 GHz on a 20” line. This was 26% better than Panasonic's Megtron-6 with HVLP copper on the same TV.
Infrastructure OEM – Tachyon had an insertion loss of 0.605 dB/in. at 12.5 GHz on a 0.005” wide line that was 20” long.
SET2DIL – Tachyon had an insertion loss of 0.27dB/in at 4 GHz on a 0.0065” wide line.

Tachyon and Tachyon-100G laminates and prepregs exhibit exceptional electrical properties (Dk of 3.0 that is stable between -55°C and +125°C up to 40 GHz and ultra-low Df of 0.002), making them suitable for next-generation designs requiring backplanes and daughter cards to run at faster data rates. Tachyon and Tachyon-100G materials use spread glass and reduced profile VLP-2 copper (very low profile copper with 2 µm Rz surface roughness copper foil) to mitigate PCB induced differential skew, improve signal rise times, and reduce jitter and intersymbol interference (ISI).

Tachyon and Tachyon-100G materials are available in optimized laminate and prepreg forms in typical thicknesses and standard panel sizes to provide complete material solutions for high-speed digital designs. Tachyon and Tachyon-100G are in the same UL-family as Isola’s I-Tera MT very-low loss material and have the same PCB-manufacturing parameters. The 70-minute curing cycle at 200°C for Tachyon and Tachyon-100G allows them to be used as either a core or prepreg in hybrid FR-4 builds.

Tarun Amla, Executive Vice President and Chief Technology Officer at Isola, stated, “The industry has demanded a product with PTFE-type electrical properties and FR-4-type processing for quite some time. Tachyon-100G required developing a thermosetting matrix that exhibits dielectric performance on par with PTFE, thermal performance exceeding most high-reliability resin systems, and processing similar to standard FR-4-type products. The lamination cycle for Tachyon-100G offers a 50% increase in press productivity. Since Tachyon-100G does not require plasma, major improvements in throughput and cycle time can be realized to significantly reduce the total cost of ownership.”

Fred Hickman, Senior Director of High-Speed Digital Products at Isola, added, “We are confident that Tachyon-100G will be the best overall material solution to achieve 100Gbe data rates.”