Isola I-Tera MT40 PCB Laminate: Very Low Loss Material for High-Speed Digital and RF/Microwave Designs

Material selection in mixed-signal PCB design has always involved uncomfortable compromises. PTFE-based laminates give you the low dielectric loss you need for RF circuits, but they’re notoriously difficult to fabricate — plasma desmear, specialized drilling, dedicated press cycles, and limited via reliability at fine pitches. Standard FR-4 processes the way you need it to, but the signal loss above 3 GHz is catastrophic for anything resembling a modern data rate. For years, the only way to get both properties on the same board was an expensive hybrid construction where you paid premium costs for both materials and accepted the process complexity that came with combining them.

Isola I-Tera MT40 occupies a genuinely useful position in that gap. It delivers PTFE-competitive dielectric loss without requiring a single PTFE-specific fabrication step, it offers multiple Dk options that give you impedance design flexibility unavailable in fixed-Dk materials, and its thermal profile makes it compatible with the most demanding applications in aerospace, defense, automotive radar, and 5G infrastructure. This guide covers the full technical picture for engineers who need to evaluate, specify, and design with it.

What Is Isola I-Tera MT40?

Isola I-Tera MT40 is a very low-loss laminate and prepreg designed for high-speed digital and RF/microwave printed circuit designs. It sits in the middle tier of Isola’s performance laminate portfolio — above I-Speed (which handles designs up to approximately 25 Gbps) and below Tachyon 100G (which targets 100 Gbps and beyond) — while simultaneously serving as an RF/microwave material up to W-band frequencies through its RF/MW variant.

The “MT” in the product name stands for “Multi-Temperature,” reflecting one of the material’s core engineering achievements: a dielectric constant that remains genuinely stable across temperatures from −55°C to +125°C and across frequencies from a few GHz up to W-band. This stability isn’t just a datasheet claim — it’s what makes the material viable for automotive radar systems operating in outdoor environments, military electronics subjected to wide thermal excursions, and satellite communication hardware running continuous duty cycles.

I-Tera MT40 is offered in two closely related variants: the standard version for high-speed digital and mixed-signal applications, and I-Tera MT40 (RF/MW) for dedicated RF/microwave and mmWave circuit designs. The RF/MW variant is available with four distinct Dk target values — 3.38, 3.45, 3.60, and 3.75 — which is a capability unique in the FR-4-process-compatible laminate category and the source of much of I-Tera MT40’s design flexibility.

Isola I-Tera MT40 Complete Specifications

These properties are sourced from Isola’s current published datasheets and should be confirmed against the latest revision at isola-group.com for final design work.

Electrical Properties

Parameter	Value	Frequency	Test Method
Dielectric Constant (Dk) — Standard	3.45	5–20 GHz	IPC-TM-650
Dielectric Constant (Dk) — RF/MW options	3.38 / 3.45 / 3.60 / 3.75	10 GHz (z-axis)	IPC-TM-650
Dissipation Factor (Df) — Standard	0.0031	2, 5, 10 GHz	IPC-TM-650
Dissipation Factor (Df) — RF/MW variant	0.0028–0.0035	10 GHz	IPC-TM-650
Dk Stability vs. Temperature	Stable	−55°C to +125°C	—
Dk Stability vs. Frequency	Stable to W-band	DC to 110 GHz	—

The four available Dk values in the RF/MW variant — 3.38, 3.45, 3.60, and 3.75 — deserve particular attention. As Microwave Journal reported from IMS2023, the higher Dk values enable miniaturization of circuit structures for a given frequency or wavelength, in support of reduced circuit size, weight, and power (SWaP) in military and aerospace applications. This is not a trivial benefit. Designing a 10 GHz bandpass filter on a Dk 3.75 substrate versus a Dk 3.38 substrate reduces the physical size of every resonant structure proportionally, which on a board space-constrained radar front-end or missile guidance PCB can mean the difference between a design that fits and one that doesn’t.

Thermal and Mechanical Properties

Parameter	Value	Test Method
Glass Transition Temperature (Tg)	215°C	DSC
Glass Transition Temperature (Tg)	210°C	TMA
Glass Transition Temperature (Tg)	230°C	DMA
Decomposition Temperature (Td)	360°C	TGA @ 5% wt. loss
Z-axis CTE (50–260°C, total)	2.8%	IPC-TM-650
T-260	>60 minutes	IPC-TM-650 2.4.24.1
T-288	>60 minutes	IPC-TM-650 2.4.24.1
Thermal Conductivity	0.61 W/m·K	—
Water Absorption	0.1%	IPC-TM-650 2.6.2.1

Compliance and Processing Attributes

Standard / Feature	Status
RoHS	Compliant
UL File Number	E41625
IPC-4103 Slash Sheet	/17
UL94 Flammability	V-0
CAF Resistance	Demonstrated
Lead-Free Assembly	Compatible
FR-4 Process Compatible	Yes
PTFE-Special Processing Required	No
Multiple Lamination Cycles	Supported
HDI / Microvia Compatible	Yes
Sequential Lamination	Capable
Dimensional Stability	High

Material Availability

Form	Specification
Core laminate thickness (standard)	2 to 18 mil; 20 and 30 mil available
RF/MW laminate thickness	10, 20, 30, 60 mil (0.25, 0.51, 0.76, 1.52 mm)
Core: full sheets or panels	Available
Prepreg: panel or roll	Available; tooling of prepreg panels available
Copper foil type	HVLP (VLP2) ≤2.5 µm Rz JIS; HTE Grade 3
Copper weights	½, 1, 2 oz (18, 35, 70 µm)
Glass fabric	Spread weave both directions, all constructions

What Makes I-Tera MT40 a Genuine PTFE Alternative

The phrase “cost-effective alternative to PTFE” appears in almost every competing laminate’s marketing literature. For most of those materials, it’s aspirational copywriting. For Isola I-Tera MT40, the case is substantively stronger — and understanding why requires looking at what actually makes PTFE difficult to use in production.

H3: FR-4 Process Compatibility — No Special Through-Hole Treatment

PTFE-based RF laminates have a processing problem: the fluoropolymer surface is chemically inert and won’t bond reliably to the copper plating in drilled through-holes without aggressive surface treatment — typically sodium naphthalene etching or plasma desmear using CF4/O2 chemistry. Both require dedicated equipment, are relatively expensive to run, and introduce process variables that affect via reliability in ways that are hard to control in production.

I-Tera MT40 does not require any special through-hole treatments commonly needed when processing PTFE-based laminate materials. Standard PCB fabrication equipment handles it without modification. Standard drill bits and feeds. Standard aqueous desmear chemistry. Standard oxide or oxide-replacement treatment for inner layers. This process compatibility keeps fabrication costs down and opens the material to a much wider range of approved PCB vendors than PTFE alternatives.

H3: Dimensional Stability — A Real FR-4 Process Advantage

PTFE laminates are mechanically soft and dimensionally unstable compared to woven-glass-reinforced systems. They can creep during lamination press cycles, making tight layer-to-layer registration in multilayer constructions challenging. I-Tera MT40 is reinforced with spread-weave glass fabric in both directions — the same glass reinforcement architecture as high-performance FR-4 laminates — giving it the dimensional stability needed for fine-pitch HDI constructions and high-layer-count boards where registration tolerances are tight.

H3: The Spread-Weave Glass Architecture

All I-Tera MT40 glass is spread weave in both directions — this isn’t a selective option for premium constructions, it’s standard throughout the product. Spread weave reduces the fiber weave effect: the periodic Dk variation caused by alternating glass bundles and resin pockets in plain-weave fabrics that creates intra-pair skew on differential lines. For mixed-signal boards where I-Tera MT40 carries both digital SerDes lanes and RF transmission lines, spread-weave glass provides more consistent dielectric behavior in both circuit types simultaneously.

H3: Multiple Dk Options — A Capability PTFE Materials Often Lack

The availability of Dk options at 3.38, 3.45, 3.60, and 3.75 in the RF/MW variant is unusual. Most PTFE-based RF laminates are available only at a specific Dk value with minimal flexibility. The I-Tera MT40 RF/MW family allows a designer to choose the Dk that best suits their circuit requirements — whether that means minimizing conductor width to reduce board area, hitting a specific impedance with available layer thicknesses, or simply matching the Dk of an existing system for a board-to-board material migration.

Understanding I-Tera MT40’s Unique Position in the Isola Laminate Portfolio

Isola I-Tera MT40 is one of the few materials in Isola’s portfolio that genuinely bridges two distinct application categories — high-speed digital and RF/microwave — in a single product family. That dual positioning explains why it shows up on approved materials lists across industries that rarely share anything else.

Material	Dk (10 GHz)	Df (10 GHz)	Tg (DSC)	HSD Range	RF/MW Capable	Halogen-Free
I-Speed	3.63	0.0060	180°C	To ~25 Gbps	No	No
I-Tera MT40	3.45	0.0031	215°C	25–56 Gbps	Yes, to W-band	No
Tachyon 100G	3.02	0.0021	215°C	100 Gbps+	Partial	No
Astra MT77	2.97	0.0017	200°C	Not primary	Yes, mmWave	No
TerraGreen 400G	3.15	0.0017	200°C	100 Gbps+	Partial	Yes
Megtron 6 (Panasonic)	3.40	0.0020	185°C	56–100 Gbps	Limited	Yes
Rogers RO4350B	3.48	0.0037	280°C	Limited	Yes, to 40 GHz	No

The critical insight from this comparison: I-Tera MT40 is the only material in Isola’s line that comfortably occupies both the HSD and RF/MW categories. Tachyon 100G is optimized for HSD and can serve at some RF frequencies but is primarily a digital board material. Astra MT77 is optimized for RF/mmWave and can support HSD but is primarily an RF material. I-Tera MT40 is genuinely at home in both.

Another circuit material well matched to Astra MT77 in CTE, I-Tera MT40 (RF/MW) has a slightly higher Dk of 3.45 at 10 GHz but also with very low loss, signified by a Df of 0.0031 at 10 GHz, and both have the qualities needed for many emerging mmWave circuit applications such as automotive radar and 5G wireless.

Where Isola I-Tera MT40 Belongs: Real Application Scenarios

H3: Hybrid RF/Digital Boards — The I-Tera MT40 Sweet Spot

The best single application category for I-Tera MT40 is complex hybrid PCB constructions where digital SerDes interfaces and RF/microwave signal paths must coexist on the same board or in the same stackup. Examples include: 5G active antenna unit (AAU) boards where digital baseband processing feeds directly into analog RF chains; software-defined radio hardware with digital back-end and RF front-end on the same PCB; and phased array radar modules where digital beam-steering control logic connects to the RF antenna distribution network.

For these designs, using Astra MT77 throughout is often over-specified on the digital sections, and using a high-speed digital material on the RF sections leaves signal-sensitive analog paths on a substrate that isn’t quite right for their frequency range. I-Tera MT40 is often the material of choice for complex hybrid builds because its Df of 0.0031, Dk stability to W-band, and CTE compatibility with both Tachyon 100G and Astra MT77 make it a natural bridge material — and it processes entirely on standard FR-4 equipment throughout.

H3: Aerospace and Defense Electronics

Aerospace and defense consistently appears among I-Tera MT40’s primary markets, and the reasons are layered. The Dk stability from −55°C to +125°C is critical for airborne and ground-based radar systems that see the full ambient temperature range of field deployment. The multiple Dk options in the RF/MW variant support the SWaP (size, weight, and power) optimization that drives nearly every defense electronics program — choosing a higher Dk means physically smaller resonant structures at the same frequency, which directly reduces board area and weight in space-constrained enclosures.

As Microwave Journal reported, the higher Dk values in I-Tera MT40 enable miniaturization of circuit structures for a given frequency or wavelength, in support of reduced circuit size, weight, and power in military and aerospace applications. The material is also cited for its compatibility with low Earth orbit satellite (LEOS) circuit applications — I-Tera MT40 and I-Tera MT40 (RF/MW) are available with typical temperature-stable Dk values ranging from 3.38 to 3.75 and Df values from 0.0028 to 0.0035 for this demanding application category.

H3: 5G Infrastructure — Sub-6 GHz and Mid-Band Applications

5G infrastructure hybrid builds using I-Tera MT40 or Tachyon 100G for digital sections and Astra MT77 for RF sections are a well-established design pattern in the base station supply chain. I-Tera MT40 handles the digital baseband processing sections at 25–56 Gbaud while Astra MT77 handles the RF front-end at sub-6 GHz and lower mmWave bands. The Df of 0.0031 provides meaningful signal integrity improvement over standard FR-4 for the digital channels, while the material’s thermal compatibility with Astra MT77 ensures the hybrid stackup is manufacturable without differential expansion causing warpage or delamination.

For 5G base stations that don’t require mmWave frequencies — particularly the sub-6 GHz rural macro installations and urban mid-band deployments — I-Tera MT40 alone can serve both digital and RF sections, eliminating the complexity of a true hybrid construction while meeting both signal integrity and RF performance requirements.

H3: High-Speed Digital Networking — 10 to 56 Gbps

In the ladder of Isola’s high-speed digital materials, I-Tera MT40 occupies the 10–56 Gbps range. I-Speed handles designs up to approximately 25 Gbps with its Df of 0.0060, I-Tera MT40 handles higher speeds and offers multiple Dk options for impedance flexibility, and Tachyon 100G is optimized for 100 Gbps and beyond. For 25G and 40G Ethernet line cards, 100G short-reach optical transceiver boards, and mid-range switch ASICs where trace lengths are moderate and Df of 0.0031 provides comfortable margin, I-Tera MT40 is the cost-appropriate choice — delivering meaningful loss improvement over I-Speed without the premium of Tachyon 100G.

H3: Automotive Radar and Transportation Electronics

The automotive sector’s growing demand for advanced driver assistance systems (ADAS) and autonomous vehicle radar has created a large volume market for RF laminate materials at 24 GHz, 77 GHz, and 79 GHz. While Astra MT77 is the dedicated Isola solution for 77 GHz radar systems, I-Tera MT40 (RF/MW) is applicable to 24 GHz short-range radar, V2X communication boards, and automotive Ethernet boards where the 3.45 Dk and Df of 0.0031 provide adequate RF performance at lower frequencies. The thermal compatibility between I-Tera MT40 and Astra MT77 also supports hybrid automotive PCB constructions where both radar front-ends and digital processing are integrated.

H3: Medical and Industrial High-Frequency Equipment

Medical imaging systems, industrial radar sensors, and precision instrumentation in the 3–20 GHz range represent a consistent market for I-Tera MT40. The material’s excellent reliability profile — CAF resistance, high Tg, RoHS compliance, and long field-proven track record — matches the qualification standards required in medical and industrial equipment programs with extended product lifecycles. The spread-weave glass and multiple Dk options give design teams the dimensional stability and impedance flexibility needed for precise microwave filter and coupler designs used in imaging and sensing systems.

I-Tera MT40 vs. Competing Materials: Engineering the Right Choice

When program material selection comes down to a shortlist, here’s the honest cross-material comparison that matters.

Material	Manufacturer	Dk (10 GHz)	Df (10 GHz)	PTFE Process Req.	FR-4 Compatible	Dual HSD+RF?
I-Tera MT40	Isola	3.38–3.75	0.0028–0.0035	No	Yes	Yes
Astra MT77	Isola	2.97	0.0017	No	Yes	No (RF primary)
Tachyon 100G	Isola	3.02	0.0021	No	Yes	No (HSD primary)
TerraGreen 400G	Isola	3.15	0.0017	No	Yes	Partial
Rogers RO4350B	Rogers	3.48	0.0037	Partial	Partial	Limited
Rogers RO3003	Rogers	3.00	0.0010	Yes	No	No
Megtron 6	Panasonic	3.40	0.0020	No	Yes	Limited

Against Rogers RO4350B — the traditional reference point for FR-4-process-compatible RF laminates — I-Tera MT40 offers lower Df (0.0031 versus 0.0037), broader Dk choice, and genuine full FR-4 process compatibility where RO4350B requires some process accommodations. The I-Tera MT40 RF/MW variant’s Dk range of 3.38–3.75 also covers the same territory as RO4350B’s fixed 3.48 Dk, giving designers more flexibility to optimize their specific design.

Against Megtron 6 from Panasonic as a hybrid digital/RF alternative, I-Tera MT40 has a higher Df (0.0031 versus Megtron 6’s 0.0020) but offers greater Dk flexibility and the advantage of Isola’s global supply chain with broader fabricator qualification. For programs where the loss budget can accommodate Df of 0.0031 and impedance flexibility is more valuable than maximum loss performance, I-Tera MT40 is competitive.

Stackup Design and Processing Guidelines for I-Tera MT40

H4: Use Construction-Level Dk/Df Tables, Not Headline Specs

The datasheet headline values of Dk 3.45 and Df 0.0031 represent a specific construction at a specific resin content. Actual Dk varies across the available prepreg and core constructions. Download Isola’s current Dk/Df construction tables from isola-group.com and use the specific values for your glass style and resin content in your 2D field solver. Construction-level Dk accuracy matters most at 28 GHz and above, where even a 2–3% Dk error translates to meaningful impedance mismatch and phase velocity errors.

H4: Copper Foil Selection for RF vs. Digital Layers

I-Tera MT40 is available with HVLP (VLP2) copper at ≤2.5 µm Rz JIS and standard HTE Grade 3 foil. For RF/microwave layers operating above 5 GHz, HVLP copper is strongly preferred — the reduced surface roughness decreases conductor loss at the frequencies where skin depth approaches foil roughness dimensions. For digital signal layers at 10 Gbps and below, standard HTE foil provides cost optimization without significant performance penalty. For 25–56 Gbps digital layers, HVLP copper is the appropriate specification.

Note that PIM (Passive Intermodulation) performance in antenna-adjacent applications is directly influenced by copper foil treatment roughness, and PIM values presented by Isola for I-Tera MT40 were achieved with VLP-2 copper foil — relevant if your design has any passive component near a high-power transmit path.

H4: Hybrid Stackup Planning with Astra MT77 and Tachyon 100G

I-Tera MT40 is thermally and dimensionally compatible with both Astra MT77 and Tachyon 100G for hybrid PCB constructions. This CTE compatibility is documented and intentional — Isola specifically designs I-Tera MT40 with a Z-axis CTE profile (2.8% total expansion, 50–260°C) that works alongside Astra MT77 and Tachyon 100G in mixed-material stackups. For ISOLA PCB fabrication of complex hybrid boards, confirm the specific core and prepreg construction pairings with your fabricator’s stackup engineer before finalizing the design.

H4: No Special Through-Hole Treatment — But Follow Isola’s Processing Recommendations

While I-Tera MT40 doesn’t require PTFE-specific plasma desmear or sodium etch, it benefits from following Isola’s published processing recommendations for optimal via reliability. Inner layer bonding treatments, lamination press cycle parameters, and plating chemistry choices can all affect via and microvia quality in high-performance laminates. Engage your fabricator’s engineering team with Isola’s processing guide for I-Tera MT40 before the first prototype build.

H4: HDI and Sequential Lamination Capability

I-Tera MT40 supports HDI microvia construction and sequential lamination processes. For multilayer boards incorporating blind and buried vias or any-layer HDI structures, the material’s dimensional stability under multiple press cycles — a direct benefit of its glass-reinforced architecture versus PTFE — makes it more predictable in production than PTFE alternatives. Specify the construction-level prepreg and core selections for each sequential lamination stage in your fab notes rather than specifying only the finished board thickness.

Useful Resources for Isola I-Tera MT40

The following links give you direct access to the specifications, datasheets, construction tables, and engineering tools needed for I-Tera MT40 design and procurement work.

• Isola I-Tera MT40 Official Product Page — Standard HSD variant: product overview, constructions, and documentation (Rev. L, Oct. 2025)
• Isola I-Tera MT40 (RF/MW) Product Page — RF/Microwave variant with four Dk options: 3.38 / 3.45 / 3.60 / 3.75
• I-Tera MT40 Datasheet PDF — Full electrical, thermal, and mechanical property tables
• I-Tera MT40 (RF/MW) Datasheet PDF — RF/MW variant with Dk/Df values for all four Dk options
• I-Tera MT40 Dk/Df Construction Tables PDF — Per-construction Dk/Df values by glass style and resin content
• Isola High-Speed Digital Portfolio — Cross-product comparison: I-Speed, I-Tera MT40, Tachyon 100G, TerraGreen 400G, FR408HR
• Isola IsoStack Stackup Design Tool — Free stackup modeling tool with construction-level Dk values for I-Tera MT40
• ISOLA PCB Laminate Selection Guide at PCBSync — Practical Isola material selection guide with application mapping across the full portfolio
• PCB Directory — Isola I-Tera MT40 Listing — Third-party spec database with distributor cross-reference
• Microwaves & RF — PCB Materials at Higher Frequencies — Independent technical analysis of I-Tera MT40 at mmWave vs. competing materials

Frequently Asked Questions About Isola I-Tera MT40

FAQ 1: What is the difference between I-Tera MT40 and I-Tera MT40 (RF/MW)?

Both products share the same resin system, thermal properties, and FR-4 process compatibility. The key difference is the glass style and available Dk options. The standard I-Tera MT40 is optimized for high-speed digital applications with a nominal Dk of 3.45 and Df of 0.0031, and is the version to specify for multilayer digital boards, mixed HSD/RF boards, and general-purpose very-low-loss applications. The I-Tera MT40 (RF/MW) variant is specifically engineered for dedicated RF and microwave circuit designs, offering four controlled Dk options (3.38, 3.45, 3.60, 3.75) with tighter Dk tolerances and optimized glass constructions for RF design repeatability. If your design is primarily digital with some RF content, use the standard variant. If your primary circuits are RF/microwave — filters, amplifiers, antenna feeds, phased array elements — specify the RF/MW version and select the Dk that best serves your circuit geometry requirements.

FAQ 2: Does I-Tera MT40 really not need plasma desmear or special through-hole treatment?

Correct. I-Tera MT40 does not require any special through-hole treatments commonly needed when processing PTFE-based laminate materials. Standard PCB fabrication desmear chemistry — either permanganate-based or alkaline permanganate — is appropriate for I-Tera MT40 via preparation. This is one of the fundamental manufacturing advantages of the material over PTFE alternatives. The glass-reinforced construction provides the mechanical support that makes standard drill and desmear processes reliable, whereas PTFE’s soft and inert surface requires aggressive chemical surface activation for good copper-to-barrel adhesion. Engineers switching from PTFE to I-Tera MT40 on cost or processability grounds typically find that their existing approved PCB vendor list can accommodate I-Tera MT40 without any new process qualifications.

FAQ 3: How does I-Tera MT40 compare to Rogers RO4350B for RF/microwave applications?

Rogers RO4350B has been the dominant reference material for FR-4-process-compatible RF laminates for many years. I-Tera MT40 compares favorably in several respects: Df of 0.0031 versus RO4350B’s 0.0037 at 10 GHz gives I-Tera MT40 lower insertion loss at equal frequency and trace length. I-Tera MT40 also offers multiple Dk options (3.38, 3.45, 3.60, 3.75) where RO4350B is fixed at 3.48, providing design flexibility that RO4350B cannot match. The tradeoff is that RO4350B has a longer field qualification history in some specific application segments and may already be on an approved vendor list where I-Tera MT40 requires a new qualification. For new designs where either material could be qualified, I-Tera MT40’s combination of lower Df, Dk flexibility, and genuine full FR-4 process compatibility makes it a strong candidate for the primary specification.

FAQ 4: Can I-Tera MT40 be used in the same hybrid stackup as Astra MT77 or Tachyon 100G?

Yes — and this hybrid capability is one of I-Tera MT40’s documented strengths. I-Tera MT40 is specifically identified as compatible with Isola’s Astra MT77 and Tachyon 100G materials for hybrid constructions, with CTE values across operating temperatures that are compatible enough to prevent the differential expansion mismatches that cause hybrid board failures. Compatibility with a large choice of Isola materials — from high-reliability epoxy systems like 370HR to low-loss HSD products like I-Tera MT40 or Tachyon 100G — creates flexibility in hybrid stackup design. Confirm the specific construction pairings with your fabricator’s stackup engineer and validate the model using Isola’s IsoStack tool before committing to production.

FAQ 5: What signal speeds can I-Tera MT40 handle, and when should I step up to Tachyon 100G?

I-Tera MT40 with Df of 0.0031 handles digital signals confidently in the 10–56 Gbps range. For channels at 25 Gbaud NRZ with trace lengths under 15 inches, I-Tera MT40 typically provides sufficient loss margin. At 56 Gbaud NRZ or PAM4 with traces beyond 10–12 inches, run your SI simulation explicitly before committing — the decision depends on your specific loss budget, connector launch design, and equalization architecture. Tachyon 100G (Df 0.0021) is optimized for 100 Gbps and beyond, providing roughly 26% lower Df than I-Tera MT40. If your simulation shows I-Tera MT40 closes the channel with margin, there’s no reason to pay for Tachyon 100G. If the channel is marginal or failing with I-Tera MT40, stepping up to Tachyon 100G will typically recover 0.5–1.5 dB of insertion loss margin depending on trace length and frequency — often enough to move a borderline channel into compliance.

The Engineering Case for Isola I-Tera MT40

No material in PCB design history has eliminated every compromise, and Isola I-Tera MT40 is no exception. Its Df of 0.0031 is higher than Tachyon 100G or Astra MT77, so at the extreme ends of insertion loss sensitivity — very long channels, very high data rates, very wide RF bandwidths at mmWave — you will eventually need to step up. But for the broad middle of mixed-signal design requirements in 5G infrastructure, aerospace electronics, industrial sensing, and 25–56 Gbps networking, I-Tera MT40 solves an important problem in one material: genuine low loss, genuine W-band Dk stability, multiple Dk options for design flexibility, full FR-4 process compatibility with no PTFE-style fabrication penalties, and a thermal profile that enables hybrid constructions with Isola’s RF and HSD specialists.

The combination of I-Tera MT40’s flexibility with the cost structure that comes from standard processing is why it remains, year after year, one of the most specified materials for complex hybrid PCBs across industries. When your design needs to serve two masters — digital signal integrity and RF electrical performance — this is the material most likely to do both reliably.