Isola Tachyon 100G聽delivers Dk 3.02 and Df 0.0021 stable to 100 GHz 鈥� the benchmark non-halogen-free laminate for 100Gbps+ HSD design. Full technical guide: complete specs, HVLP copper options, spread glass, Z-axis CTE advantage, processing parameters, Megtron 6 comparison data, and hybrid build strategy with Astra MT77.
Primary keyword: Isola Tachyon 100G | ~3,500 words
If there’s a single PCB laminate that changed the conversation around high-speed digital material selection in the last decade, it’s Isola Tachyon 100G. When Isola introduced it in 2014, the headline was striking: PTFE-type dielectric performance with FR-4-type processing. That combination 鈥� Dk 3.02, Df 0.0021, stable to 100 GHz, processable on standard equipment, no plasma desmear required 鈥� had been exactly what the industry wanted for router backplanes and line cards targeting 100 Gigabit Ethernet, but nobody had delivered it cleanly in a standard laminate format before.
More than a decade later, Tachyon 100G remains the reference material for non-halogen-free high-speed digital PCB design at and above 100 Gb/s data rates. It has been qualified at dozens of OEM programs across data center switching, AI/ML accelerator hardware, and high-performance computing, and it continues to be updated 鈥� the current Revision G (2025) adds HVLP3 and advanced RTF copper options and a 20 mil thickness offering that didn’t exist at initial release. This guide covers the full technical picture: specifications, construction details, processing parameters, competitive positioning, hybrid build strategy, and exactly where Tachyon 100G belongs in your material selection.
What Isola Tachyon 100G Was Designed to Solve
The engineering problem that motivated Tachyon 100G was specific and well-understood by anyone who had struggled to close channel loss budgets on long backplane designs in the 10 Gb/s generation. As data rates moved from 10 Gb/s to 25 Gb/s per lane, and the industry was already planning the path to 100 Gb/s aggregate via four 25 Gb/s lanes (100GbE), two material classes dominated: standard FR-4-type laminates that were processable but had Df values around 0.008鈥�0.020, and PTFE-based RF microwave materials that had Df values below 0.003 but required specialized manufacturing equipment and processes most PCB shops didn’t have.
Tachyon 100G was engineered to close that gap. Tarun Amla, then Chief Technology Officer at Isola, stated at the material’s launch: “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 product delivered on that specification. On the IBM SPP Signal Integrity test vehicle, Tachyon 100G insertion loss measurements on S3 and S6 striplines were 37% and 43% better than Megtron 6 with HVLP copper. The effective dissipation factor was 72% and 92% better than Megtron 6 on the same structures. Those were not incremental improvements 鈥� they were generational step changes in an industry where shaving a few tenths of dB per inch from insertion loss is what separates designs that close from designs that require active retimers.
Core Electrical Properties: The Numbers That Matter
Tachyon 100G materials exhibit exceptional electrical properties that are very stable over a broad frequency and temperature range between -55掳C and +125掳C up to 100 GHz. The headline numbers are Dk 3.02 and Df 0.0021 鈥� but the stability of those numbers is as important as the absolute values.
Electrical Properties by Frequency
| Property | @ 2 GHz | @ 5 GHz | @ 10 GHz | Notes |
| Dielectric Constant (Dk) | 3.04 | 3.02 | 3.02 | Bereskin Stripline |
| Dissipation Factor (Df) | 0.0021 | 0.0021 | 0.0021 | Bereskin Stripline |
The flatness of Dk across this frequency range is what enables the material to be characterized as broadband-stable. A Dk that changes from 3.04 to 3.02 between 2 and 10 GHz is not causing dispersion that degrades wideband pulse integrity. For 56 Gbps PAM4 channels 鈥� which have a Nyquist frequency of 14 GHz and spectral content out to 28 GHz and beyond 鈥� a flat Dk across that frequency range is not optional, it’s the specification.
The Df of 0.0021 is stable through 100 GHz per the official product description. That stability makes Tachyon 100G useful not just for current data center infrastructure but for designs being developed today for 400 Gb/s and 800 Gb/s SerDes interfaces that will stress channel loss budgets well into the mmWave frequency band.
Full Electrical and Thermal Property Table
| Property | Typical Value | Test Method / Notes |
| Dielectric Constant (Dk) | 3.02 | Stable -55 to +125掳C, up to 100 GHz |
| Dissipation Factor (Df) | 0.0021 | 2, 5, 10 GHz |
| Dielectric Strength | 60 kV/mm (1500 V/mil) | IPC-TM-650 |
| Volume Resistivity | 鈮�1 脳 10鈦� M惟路cm | IPC-TM-650 |
| Surface Resistivity | 鈮�1 脳 10鈦� M惟 | IPC-TM-650 |
| Glass Transition Temp (Tg) 鈥� DSC | 215掳颁 | Long-term data (Rev F update) |
| Glass Transition Temp (Tg) 鈥� TMA | 210掳颁 | |
| Glass Transition Temp (Tg) 鈥� DMA | 230掳颁 | |
| Decomposition Temp (Td) | 360掳颁 | TGA, 5% weight loss |
| Z-Axis CTE (50鈥�260掳C, total) | ~2.5% | Improved 30%+ vs original Tachyon |
| Moisture Absorption | 0.05% | Low moisture sensitivity |
| T260 | >60 min | IPC-TM-650 |
| T288 | >60 min | IPC-TM-650 |
| T300 | >20 min | IPC-TM-650 |
| Peel Strength | 0.79 N/mm (4.5 lb/in) | Standard copper |
| Peel Strength @ 125掳C | 0.96 N/mm (5.5 lb/in) | Post-thermal stress |
| Thermal Conductivity | 0.42 W/m路K | -100 to +250掳C |
| UL Flammability | V-0 | UL File E41625 |
| RoHS | Compliant | |
| IPC Specification | IPC-4101 |
Why the 215掳颁 Tg Sets Tachyon 100G Apart Within the Isola Lineup
The DSC Tg of 215掳颁 is the highest among Isola’s high-speed digital material family. The TerraGreen 400G series 鈥� which beats Tachyon 100G on Df 鈥� has Tg 200掳颁. I-Tera MT40 has Tg 200掳颁. For programs where thermal margin is a hard requirement, particularly high-layer-count line cards that see elevated temperatures in densely packed chassis, Tachyon 100G’s 215掳颁 Tg provides buffer that the lower-Tg alternatives cannot match.
The T260 and T288 ratings of >60 minutes each support the most demanding lead-free assembly conditions encountered in production. Six passes at 260掳C reflow and six passes at 288掳C solder float give PCB assembly operations the margin to handle rework, multiple assembly passes, and aggressive reflow profiles without material degradation.
The Three Signal Integrity Technologies Inside Tachyon 100G
The electrical performance of Tachyon 100G doesn’t come from the resin system alone 鈥� it comes from the coordinated engineering of three elements: the resin chemistry, the copper foil specification, and the glass fabric. All three contribute to different aspects of channel performance, and specifying the material correctly means understanding what each one does.
The Ultra-Low Loss Resin Chemistry
The resin system in Tachyon 100G achieves Df 0.0021 by engineering low polarity into the cured polymer matrix, minimizing the dielectric relaxation mechanisms that generate loss in standard epoxy resins at multi-gigahertz frequencies. Standard FR-4 epoxy resins have polar functional groups that respond to the electric field at high frequencies, converting signal energy to heat. The thermosetting matrix in Tachyon 100G reduces that polarization response across the frequency range that matters for high-speed digital channels.
The practical consequence is that the resin also delivers exceptional adhesive bond strength between the resin and the copper foil 鈥� the very high adhesive bond between the resin and the metal enables the use of ultra smooth copper that would otherwise have adhesion problems with standard epoxy systems. In most low-loss formulations, reducing polarity reduces adhesion. Tachyon 100G’s chemistry manages both simultaneously, which is why smooth copper foil is compatible with this resin when it wouldn’t be with a less carefully engineered system.
HVLP Copper Foil: Reducing Conductor Loss at High Frequencies
Tachyon 100G is optimized with ultra smooth HVLP (VLP2) 2 碌m Rz copper that significantly reduces conductor losses. At 10 GHz, the skin depth in copper is approximately 0.66 碌m 鈥� current is flowing almost entirely within the top 1鈥�2 碌m of the copper surface. Standard copper foil with Rz roughness of 5鈥�10 碌m increases the effective electrical path length at those frequencies, generating conductor loss well above what the DC resistance calculation would predict.
HVLP copper at 2 碌m Rz roughly halves the roughness contribution versus standard VLP copper, directly translating to lower insertion loss per unit length at frequencies above 5 GHz. The current product offering (Revision G, 2025) has expanded the copper foil options to include HVLP3 (VLP1) at 鈮�1.1 碌m Rz JIS 鈥� an even smoother option that provides additional conductor loss reduction for the most demanding mmWave-frequency channels. RTF (Reverse-Treated Foil) at 鈮�2.5 碌m is also available, as is embedded resistor foil for designs requiring resistance-embedded layers.
Spread Glass: Controlling Fiber Weave Effect and Skew
The third engineering element is the glass fabric. Tachyon 100G products use spread glass to mitigate skew, improve rise times, reduce jitter, and increase eye width and height. Understanding why this matters requires understanding fiber weave effect.
In a standard woven glass fabric, glass bundles alternate with resin-rich zones in a periodic pattern. The dielectric constant of glass (~6) is substantially higher than that of the resin (~2.5鈥�3.0). A differential pair routed across this alternating pattern at 0掳 to the weave axis encounters a periodic variation in the effective Dk it propagates through. The two conductors of the pair may have different alignments relative to the weave, causing them to see different effective Dk values and therefore propagate at different phase velocities 鈥� differential skew. At 28 Gbaud PAM4 and above, even a few picoseconds of skew contributes meaningfully to bit error rate.
Spread glass mechanically distributes the glass fiber uniformly across the fabric, flattening the Dk periodicity and substantially reducing fiber weave effect without requiring the designer to route all differential pairs at 45掳 to the weave axis. Square weave glass is also available for Tachyon 100G as an alternative construction.
Full Product Availability and Construction Options
Current Standard Offering (Revision G, Updated March 2024)
| Parameter | Available Options |
| Laminate thickness | 2 to 20 mil (0.05 to 0.51 mm) |
| Copper foil 鈥� standard | HVLP (VLP2) 鈮�2.5 碌m Rz JIS |
| Copper foil 鈥� premium | HVLP3 (VLP1) 鈮�1.1 碌m Rz JIS |
| Copper foil 鈥� alternate | Advanced RTF 鈮�2.5 碌m Rz JIS |
| Copper foil 鈥� special | Embedded resistor foil |
| Copper weight | 陆, 1, 2 oz (18, 35, 70 碌m); heavier and thinner available |
| Prepreg | Roll or panel form; tooling of panels; moisture barrier packaging |
| Glass fabric options | Low Dk glass (Asahi Japan, Asahi Taiwan, TGI Taiwan); square weave; mechanically spread |
| UL File Number | E41625 |
The addition of HVLP3 copper and the 20 mil thickness option in Revision G reflects how Tachyon 100G continues to be updated for evolving design requirements rather than treated as a static product. The 20 mil core enables thicker backplane-style constructions in a single laminate layer, relevant for designs where minimizing layer count while achieving target impedance is a stack-up priority.
Performance and Processing Feature Summary
| Category | Attribute |
| Performance | CAF resistant |
| Low moisture absorption (0.05%) | |
| 6x 260掳C reflow capable | |
| 6x 288掳C solder float capable | |
| 0.8 mm BGA pitch capable | |
| Spread glass 鈥� skew mitigation | |
| Processing | FR-4 process compatible |
| No plasma desmear required | |
| Excellent fill and flow | |
| Multiple lamination cycles | |
| HDI technology compatible | |
| Sequential lamination capable | |
| Lead-free compatible | |
| 50% press productivity improvement vs alternatives |
The “no plasma desmear required” attribute deserves explicit attention. Plasma desmear is a specialized process step that not all PCB fabrication shops have on-line, and that adds cycle time and cost when it is available. Tachyon 100G’s compatibility with standard permanganate chemical desmear removes that processing barrier, making it accessible to a much broader fabricator base than PTFE-based low-loss materials that require plasma.
Processing Isola Tachyon 100G: Key Parameters and Discipline Points
Isola Group’s Tachyon 100G laminates are fully cured and ready for processing. The material processes similarly to other high-performance epoxy-based laminates and shares manufacturing parameters with Isola’s I-Tera MT family.
Lamination Parameters
The core lamination requirement is a time at 200掳颁 of 60 minutes. The actual cure temperature is influenced by the total thickness of the multilayer package being produced 鈥� very thick boards require longer cure times to ensure optimum material cure throughout the construction.
The general lamination cycle for dual-stage pressing calls for 50 PSI (3.5 kg/cm虏) after vacuum dwell time at 鈮�90掳C product temperature, switching to high pressure, then cooling to 135鈥�140掳C at 2.8掳C/min (5.0掳F/min) with 50 PSI maintained before opening the press. Use the full cycle for both subassembly and final lamination. The 70-minute curing cycle allows Tachyon 100G to be used as either a core or prepreg in hybrid FR-4 builds.
Stress relief bake cycles are not effective for reducing dimensional movement in high-performance laminates such as Tachyon 100G. The recommended approach is to characterize the dimensional movement of unbaked laminate on your specific panel format and apply artwork compensation factors accordingly. Most movement will be in the grain direction.
Drilling
Relative to standard FR-4 parameters, use lower chiploads and cutting speeds to drill Tachyon 100G printed circuit boards. Undercut drill geometries and high-helix tools are recommended to ensure effective resin debris removal during drilling. For high-layer-count technologies and thicker boards (above 2.5 mm), peck drilling may be necessary. Maximum hit count for drill diameters below 0.020″ is 1,000, and drills at or above 0.020″ can go up to 1,500 hits, with these numbers subject to board thickness and geometry.
Boards with multiple 2 oz copper inner layers or coarse glass weave require more conservative drill parameters. Tachyon 100G’s resin behaves differently from standard epoxy during the cutting action, and shops treating it identically to FR-4 typically see degraded hole wall quality and resin debris in the barrel on first run.
Desmear
Tachyon 100G does not require plasma desmear. Standard chemical permanganate desmear processes designed for 170掳C Tg FR-4 are the appropriate starting point. For high-reliability designs or boards exceeding 2.5 mm thickness, two passes of chemical desmear are recommended. Excessive dwell time should be avoided as it can cause etchback.
Prepreg Handling and Storage
Handle all prepreg using clean gloves. If not handled properly, Tachyon 100G prepreg will absorb moisture, which will lead to depressed Tg values and affect cure and flow during lamination. Upon receipt, all prepreg should be moved immediately from the receiving area to a controlled environment. FIFO inventory management is the standard practice. Do not vacuum seal Tachyon 100G prepreg 鈥� store in original packaging with fresh desiccant, away from catalytic environments including high radiation and intense UV.
Board Packaging for High-Temperature Assembly
For finished boards requiring long shelf life before high-temperature lead-free assembly, Isola recommends packaging in a Moisture Barrier Bag with a Humidity Indicator Card and adequate drying desiccant. Upon opening the MBB, boards should be processed within 168 hours at shop floor conditions of 鈮�30掳C/60% RH.
Tachyon 100G Z-Axis CTE: Why It Was the Design-Defining Thermal Improvement
The original Tachyon laminate had identical electrical properties to Tachyon 100G, but it was the Z-axis CTE improvement that justified introducing 100G as a distinct product. Tachyon 100G provides more than 30% improvement in Z-axis CTEs on high-layer-count PCBs compared to the original Tachyon material.
For a standard line card backplane 鈥� 36 layers, 0.300″ thick, with multiple 2 oz copper inner layers and BGAs at 0.8 mm pitch 鈥� the Z-axis CTE of the dielectric material is the governing parameter for via plating reliability during thermal cycling. As the board heats during assembly reflow, the dielectric wants to expand in Z. If the Z-axis CTE is high, the copper plating in through vias gets stretched. Over multiple thermal cycles, that fatigue accumulates in the barrel plating. For BGAs with 0.8 mm or tighter pitch on thick multilayer boards, via reliability under thermal cycling is a qualification bottleneck that Z-axis CTE directly controls.
Isola has developed Tachyon 100G with the highest level of thermal performance for high-layer-count line cards. The very low Z-axis CTE makes it a perfect choice for fine pitch BGA applications with pitches at 0.8 mm or less. That 30% Z-axis CTE reduction was a production necessity, not a marketing claim 鈥� it enabled PCB shops to build the high-layer-count Tachyon-based line cards that data center switch OEMs were designing.
Hybrid PCB Builds: Tachyon 100G With Astra MT77
One of the most practically useful properties of Tachyon 100G for system-level PCB design is its thermal compatibility with Isola Astra MT77. Tachyon 100G and Astra MT77 exhibit thermal behavior closely matched to each other, as evidenced by their similar CTE values for a wide operating temperature range of -55 to +125掳C. The thermal compatibility makes Astra MT77 and Tachyon 100G laminates and prepregs good candidates for hybrid PCBs, where one material holds RF/microwave circuits and the other handles HSD circuits.
This is not an incidental property 鈥� Isola specifically designed these materials to coexist in hybrid builds. The reason the thermal compatibility matters: if two laminates in a hybrid stack-up have significantly different CTEs, the differential expansion during lamination and during thermal cycling generates internal stresses at the material interface. Those stresses cause warpage during processing, delamination risk during assembly, and long-term fatigue at layer interfaces in the field.
When Hybrid Builds Are the Right Architecture
The hybrid Tachyon 100G / Astra MT77 build makes sense when a single board must carry both high-speed digital interfaces (100 Gb/s SerDes, PCIe 6.0, DDR5 memory buses) and RF/microwave signal paths (sub-6 GHz radio, mmWave radar, or satellite downconversion). A 5G base station DU/CU unit is a real-world example: the digital baseband processing section runs multi-gigabit Ethernet to the fiber transport, which wants Df 0.0021 and Dk 3.02, while the radio front-end uses controlled impedance transmission lines at 5.9 GHz, where Astra MT77’s Df 0.0017 and extreme Dk stability through mmWave frequencies is the better fit.
Building that board as a hybrid 鈥� Tachyon 100G on the digital layers, Astra MT77 on the RF layers 鈥� with identical lamination cycles and compatible CTEs is exactly the scenario Isola designed for.
Isola Tachyon 100G vs Competing Materials: Head-to-Head Performance Comparison
Comparison Table: High-Speed Digital and Ultra-Low-Loss Laminates
| Material | Manufacturer | Dk (10 GHz) | Df (10 GHz) | Tg | Halogen-Free | FR-4 Process |
| Tachyon 100G | Isola | 3.02 | 0.0021 | 215掳颁 | No | Yes |
| I-Tera庐 MT40 | Isola | 3.45 | 0.0031鈥�0.0034 | 200掳颁 | No | Yes |
| TerraGreen 400G | Isola | 3.15 | 0.0017 | 200掳颁 | Yes | Yes |
| TerraGreen 400G2 | Isola | 3.10 | 0.0015 | 200掳颁 | Yes | Yes |
| Astra庐 MT77 | Isola | 3.00 | 0.0017 | 200掳颁 | No | Yes |
| Megtron 6 | Panasonic | 3.60 | 0.0037 | 185掳颁 | No | Yes |
| Megtron 7 | Panasonic | 3.37 | 0.0020 | 185掳颁 | No | Yes |
| Rogers RO4350B | Rogers | 3.48 | 0.0037 | &驳迟;280掳颁 | No | No |
| FR-4 (Isola 370HR) | Isola | 3.95 | 0.018 | 180掳颁 | No | Yes |
Tachyon 100G vs Megtron 6
This is the comparison the industry originally cared most about when Tachyon 100G launched. On real test vehicles, Tachyon 100G insertion loss was 35% better than Megtron 6 with HVLP copper at 16 GHz on a Speeding Edge test vehicle, and 26% better on a storage OEM serpentine test vehicle at 12.5 GHz. These are production-qualified numbers from specific PCB designs 鈥� not controlled laboratory conditions.
The CTO of Gold Circuit Electronics, one of the original beta fabricators, summarized the commercial context: “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 vs Megtron 7
Panasonic introduced Megtron 7 as a competitive response to Tachyon 100G’s performance level, targeting Dk 3.37 and Df 0.0020. Megtron 7 closes the Df gap considerably versus Megtron 6, but the higher Dk of 3.37 vs Tachyon 100G’s 3.02 means trace widths for a given impedance are different, and propagation velocity is lower 鈥� relevant for length-matched differential pair design. Tachyon 100G’s lower Dk also provides a small dielectric loss advantage per unit length that compounds on long backplane traces.
Tachyon 100G vs TerraGreen 400G Family
This comparison is the most interesting current decision point for new designs. The TerraGreen 400G halogen-free materials launched in 2023 with Df values that beat Tachyon 100G at 28 GHz: TerraGreen 400G at Df 0.0017 and 400G2 at Df 0.0015. Isola explicitly states that the new TerraGreen circuit materials are capable of even less loss than Tachyon 100G at 28 GHz.
So why would an engineer still choose Tachyon 100G? Three reasons: the 215掳颁 Tg vs 200掳颁 for the TerraGreen grades provides thermal margin on high-layer-count line cards with heavy copper; the long qualification history across tier-1 OEM programs means Tachyon 100G has more field reliability data than the 2023-vintage 400G materials; and the TerraGreen 400G family requires halogen-free compliance, while programs that don’t have that environmental requirement can stay on Tachyon 100G without the material cost premium of the halogen-free chemistry. For programs that do need halogen-free compliance, 400G is the natural migration path from Tachyon 100G.
Application Areas Where Isola Tachyon 100G Is the Default Specification
These electrical properties provide designers a scalable solution for next-generation designs of backplanes and daughter cards, enabling 10x improvements from 10 Gb/s data rates. The applications where Tachyon 100G has become the default material specification reflect that scalable positioning:
High-Speed Digital Backplanes: The original design target. 36-layer, 24″脳36″ backplanes for router chassis and switch fabrics, with data rates of 25鈥�56 Gbps per SerDes lane. The Z-axis CTE and T260/>60-min rating enable the thermal reliability that high-layer-count, heavy-copper constructions require.
400G and 800G Ethernet Line Cards: Data center leaf-spine switches operating at 400GbE and 800GbE require channels that close on 20鈥�30 cm board-to-board paths at 56 Gbps NRZ and 112 Gbps PAM4 lane rates. Tachyon 100G’s Df 0.0021 provides the insertion loss headroom for these channels without requiring active retimers at every board edge.
AI Accelerator and GPU Interconnect Boards: AI training cluster hardware 鈥� GPU servers with NVLink or similar fabric connections, inference nodes with high-bandwidth memory (HBM) 鈥� requires PCB channels running >100 Gbps aggregate per port with tight bit error rate targets. Data center operators and hyperscalers have driven significant adoption of Tachyon 100G for 400G Ethernet switches and next-generation AI/ML accelerator boards.
High-Performance Computing Server Boards: Multi-socket compute platforms using PCIe 6.0 and CXL (Compute Express Link) interfaces, where the bandwidth density and lane rates stress FR-4-class materials beyond their useful range and where Tachyon 100G provides channel closure without specialized RF laminate processing.
Telecom Core Router Equipment: Core and aggregation router line cards carrying 400G coherent DWDM interfaces, where the forward error correction overhead requires very tight pre-FEC bit error rates that demand excellent channel quality from both the laminate and the connector system.
For design support and fabrication with Tachyon 100G and other ISOLA PCB materials, working with a fabricator experienced in high-performance laminate processing is essential to capturing the full channel performance the material is capable of delivering.
Stack-Up Design Guidance for Tachyon 100G Designs
A few practical notes for engineers laying out their first Tachyon 100G design or migrating from a Megtron 6 or I-Tera MT40 baseline:
Impedance calculation with Dk 3.02: Trace widths for a 50 惟 single-ended or 100 惟 differential target on Tachyon 100G will be narrower than equivalent calculations on FR-4 (Dk ~3.95) or Megtron 6 (Dk ~3.6). If you’re migrating a design from Megtron 6 to Tachyon 100G, the Dk shift will affect all controlled impedance traces in your stack-up. Recalculate all impedance targets from scratch using the Tachyon 100G Dk at your operating frequency, not just scale the trace widths from the Megtron 6 design.
Prepreg Dk vs laminate Dk: The composite Dk of a specific stackup layer depends on the resin content percentage of the prepreg construction. Isola provides detailed Dk/Df tables for Tachyon 100G at multiple constructions and frequencies 鈥� use those tables rather than the nominal headline Dk when modeling controlled impedance in your stack-up tool.
Back-drilling: For high-speed designs above 5 GHz, via stub resonances are a significant loss mechanism on backplane designs with long through-via stubs. Back-drilling removes the stub from the via structure. Tachyon 100G is fully compatible with standard back-drill processes.
Artwork compensation: Characterize dimensional movement on your fabricator’s specific equipment before finalizing artwork compensation factors. Do not assume bake cycle will reduce movement 鈥� it does not for high-performance laminates including Tachyon 100G.
Useful Resources and Data Downloads
| Resource | Type | Link |
| Tachyon 100G Official Product Page | Isola product page | |
| Tachyon 100G Datasheet PDF | Official datasheet | |
| Tachyon 100G Processing Guide | Fabrication guide PDF | |
| Tachyon 100G Dk/Df Tables | Frequency-specific data | |
| Tachyon 100G Documentation Page | All docs, processing guide | |
| IsoDesign Impedance Tools | Online stack-up calculator | |
| TerraGreen 400G Product Page | Halogen-free successor | |
| Astra MT77 Product Page | Hybrid build partner | |
| IPC-4101 Specification | IPC Standard | |
| UL Product iQ (File E41625) | UL Certification DB | |
| Signal Integrity Journal 鈥� Isola IMS2023 | Technical article | |
| Isola 100G Ethernet Introduction (2014) | Launch press release |
Frequently Asked Questions About Isola Tachyon 100G
1. What is the difference between original Tachyon and Tachyon 100G?
The two materials have identical electrical properties: Dk 3.02, Df 0.0021, stable from -55掳C to +125掳C. The defining difference is the Z-axis coefficient of thermal expansion: Tachyon 100G provides more than 30% improvement in Z-axis CTE compared to original Tachyon. That improvement was specifically targeted at high-layer-count line cards with multiple 2 oz copper inner layers and 0.8 mm pitch BGAs, where the original Tachyon’s higher Z-axis CTE was causing via reliability concerns during thermal cycling. The “100G” designation reflects the target application: 100 Gigabit Ethernet line cards that specifically required that improved thermal performance.
2. Does Tachyon 100G require plasma desmear, and what is the lamination cycle?
Tachyon 100G does not require plasma desmear 鈥� standard chemical permanganate desmear processes at FR-4 parameters are appropriate, which is one of the key processing advantages versus PTFE-based low-loss materials. The lamination cycle calls for 60 minutes at 200掳颁 cure temperature. The 70-minute total curing cycle represents a 50% improvement in press productivity compared to some alternative high-performance materials. For very thick boards, cure time at temperature may need to be extended to ensure complete cure throughout the multilayer package.
3. How does Tachyon 100G perform compared to Panasonic Megtron 6 in actual insertion loss measurements?
On real signal integrity test vehicles, Tachyon 100G demonstrated 35% better insertion loss than Megtron 6 with HVLP copper at 16 GHz on the Speeding Edge 16-layer test vehicle, and 26% better on a storage OEM’s 20-inch serpentine stripline at 12.5 GHz. On the IBM SPP test vehicle, the effective Df was 72% and 92% better than Megtron 6 on the S3 and S6 stripline structures respectively. These are the published beta test results from the 2014 Tachyon 100G launch announcement, from production-representative constructions at qualified fabricators.
4. Is Tachyon 100G compatible with hybrid PCB builds, and which Isola materials can be combined with it?
Yes. Tachyon 100G is specifically designed for hybrid builds with materials that have compatible thermal properties. Astra MT77 is the primary hybrid build partner 鈥� the two materials share closely matched CTE values across the -55 to +125掳C operating range, enabling mixed-material multilayer builds where Tachyon 100G carries the high-speed digital layers and Astra MT77 carries the RF/microwave layers. Tachyon 100G is in the same UL family as Isola’s I-Tera MT family and shares the same PCB manufacturing parameters, making combined builds with I-Tera MT40 practical as well. Always verify CTE compatibility and lamination press cycle compatibility with your fabricator before committing to production.
5. With the TerraGreen 400G series now offering lower Df, when should an engineer still specify Tachyon 100G?
Three scenarios justify choosing Tachyon 100G over TerraGreen 400G even though TerraGreen 400G (Df 0.0017) and 400G2 (Df 0.0015) provide lower loss tangent numbers. First, when the design requires Tg >200掳颁: Tachyon 100G’s 215掳颁 DSC Tg provides a 15掳C thermal margin advantage over the 200掳颁 Tg of all TerraGreen 400G grades 鈥� relevant for high-layer-count, high-power line cards. Second, when halogen-free compliance is not required by the OEM specification: TerraGreen 400G is a halogen-free product, which comes with a cost premium versus non-halogen-free Tachyon 100G, and the cost difference may not be justified if environmental compliance isn’t a project requirement. Third, when the fabricator has an established Tachyon 100G qualification and process: Tachyon 100G has years of production history and field reliability data that the 2023-vintage TerraGreen 400G series is still building. For programs requiring new qualification, both are valid; for programs where re-qualification introduces schedule risk, Tachyon 100G’s established status is a concrete advantage.
Engineering Summary: Tachyon 100G’s Enduring Position in High-Speed Digital Design
Isola Tachyon 100G solved a real engineering problem when it launched in 2014: it delivered PTFE-class dielectric performance on standard manufacturing equipment. More than a decade later, it remains the established reference material for non-halogen-free high-speed digital PCB design at 100 Gb/s and above.
The material’s combination of Dk 3.02, Df 0.0021, Tg 215掳颁, very low Z-axis CTE, FR-4-compatible processing (including no plasma desmear), and compatibility with Astra MT77 hybrid builds creates a capability set that no single competing material fully replicates. TerraGreen 400G2 beats it on Df at 28 GHz. Megtron 7 comes close on Df. But neither combination matches Tachyon 100G’s full technical and process package at Tachyon’s price point and fabricator availability.
For new designs where halogen-free compliance is a requirement, TerraGreen 400G is the natural migration path and it does beat Tachyon 100G on loss. For everything else 鈥� long backplanes, high-layer-count line cards, AI/ML accelerator boards, 400G/800G switch fabrics, and hybrid digital/RF designs 鈥� Isola Tachyon 100G remains the material to beat.
For fabrication support, stack-up design assistance, and material sourcing across the full Isola laminate portfolio including Tachyon 100G, visit 吃瓜tv’s ISOLA PCB resource page.