Isola I-Tera MT40 delivers Dk 3.38–3.75 and Df 0.0028–0.0035 across two variants for high-speed digital and RF/microwave PCBs — no PTFE through-hole treatments required. Full technical guide: complete specs, multiple Dk option rationale, W-band stability, processing parameters, hybrid build strategy, and comparison with Tachyon 100G and Astra MT77.

Primary keyword: Isola I-Tera MT40 | ~3,200 words

Material selection for PCBs that straddle the boundary between high-speed digital and RF/microwave signal processing used to force a painful tradeoff: use a standard FR-4-process epoxy material and accept higher loss, or specify a PTFE-based material that needs specialized hole treatments, custom press cycles, and fabricators with restricted equipment capability. Isola I-Tera MT40 was built to eliminate that tradeoff. It sits deliberately at the intersection of high-speed digital and RF/microwave requirements — very low loss, multiple Dk options, stable through W-band frequencies, FR-4-process compatible, no special through-hole treatments required — and it does so while offering multiple Dk grades in both HSD and RF/MW variants that let designers tune impedance without changing the entire material system.

This guide covers the full technical picture of I-Tera MT40: both variants (HSD and RF/MW), the complete specification, the multiple Dk options and what they enable, processing parameters, how it competes against Tachyon 100G and alternatives, and the applications where its unique combination of properties gives it a design advantage no single other material fully replicates.

What Isola I-Tera MT40 Is Designed to Do

I-Tera MT40 is suitable for many of today’s high-speed digital and RF/microwave printed circuit designs. I-Tera MT40 features a dielectric constant (Dk) that is stable between -55°C and +125°C up to W-band frequencies. In addition, I-Tera MT40 offers a lower dissipation factor (Df) of 0.0031, making it a cost-effective alternative to PTFE and other commercial microwave and high-speed digital laminate materials.

Three aspects of that description are worth unpacking. First, “stable up to W-band frequencies” means the Dk holds its value from DC through 110 GHz — covering not just current data center and 5G NR applications, but millimeter-wave radar, V-band satellite links, and E-band point-to-point backhaul. Second, “cost-effective alternative to PTFE” is a direct comparison to Rogers RT/duroid, Taconic RF-60A, and similar fluoropolymer-based microwave materials. I-Tera MT40 is not as low-loss as the best PTFE laminates, but it processes like FR-4, which dramatically reduces fabrication cost and shop availability constraints. Third, the explicit positioning for both HSD and RF/microwave applications — as a single material with variants — addresses the hybrid board problem directly.

I-Tera MT40 does not require any special through-hole treatments commonly needed when processing PTFE-based laminate materials. That single sentence represents a significant manufacturing cost reduction. PTFEs require sodium etch or plasma treatment of hole walls before plating to achieve adhesion. That adds process steps, cycle time, and specialized chemistry that most PCB shops either don’t have or charge a premium to use.

The Two I-Tera MT40 Variants: HSD and RF/MW

One of the things that confuses engineers first encountering I-Tera MT40 is that it exists as two distinct product lines that share the same name but serve different primary purposes. Both are qualified under UL File Number E41625, both have Tg 215°C and Td 360°C, and both process identically. The difference is in their available Dk options and their IPC classification.

I-Tera MT40 (HSD) — High-Speed Digital Variant

The standard I-Tera MT40 laminate and prepreg is optimized for high-speed digital multilayer designs. It is offered with a nominal Dk of 3.45 and Df of 0.0031 at 2 GHz and 10 GHz. The IPC classifications are IPC-4103/17 and IPC-4101/102. Laminate thickness range is 2 to 24 mil (0.05 to 0.61 mm), covering the thin-core requirements of fine-line HDI designs all the way to thick-core backplane constructions.

All I-Tera MT40 glass is spread weave in both directions, which matters for differential signal routing in high-speed digital designs for the same reasons it matters in Tachyon 100G — spread weave reduces the periodic Dk variation that causes fiber weave-induced differential skew on fast NRZ and PAM4 channels.

I-Tera MT40 (RF/MW) — RF and Microwave Variant

The RF/MW variant extends the Dk selection to four nominal values: 3.38, 3.45, 3.60, and 3.75 at 2 and 10 GHz. Df ranges from 0.0028 to 0.0035 depending on the specific Dk grade. The temperature stability is also slightly different — the RF/MW variant specifies Dk stability from -40°C to +140°C rather than -55°C to +125°C for the HSD variant, reflecting the operating range emphasis for automotive and outdoor RF applications.

The laminate thickness range for the RF/MW variant is 10, 20, 30, and 60 mil (0.25, 0.51, 0.76, and 1.5 mm) in full-size sheets or panel form. This heavier construction range reflects the typical substrate thicknesses used in microwave circuit designs — antenna feed networks, RF power amplifier boards, and radar signal processing substrates where substrate thickness determines the physical geometry of transmission lines and radiating structures.

Full Electrical and Thermal Properties

The table below consolidates the key properties for both I-Tera MT40 variants. Note that the IPC-TM-650 2.5.5.5 test method applies to the electrical property measurements.

I-Tera MT40 Electrical and Thermal Property Table

Property	I-Tera MT40 (HSD)	I-Tera MT40 (RF/MW)	Test / Notes
Dk (standard)	3.45	3.38 / 3.45 / 3.60 / 3.75	@ 2 GHz, 10 GHz
Df (standard)	0.0031	0.0028 – 0.0035	@ 2 GHz, 10 GHz
Dk thermal stability	-55°C to +125°C	-40°C to +140°C	Stable to W-band
Tg (DSC)	215°C	215°C	Long-term data (Rev E)
Tg (TMA)	210°C	210°C
Tg (DMA)	230°C	230°C
Td	360°C	360°C	TGA, 5% wt loss
Z-Axis CTE (50–260°C)	~2.8%	—	TMA
T260	>60 min	>60 min	IPC-TM-650
T288	>60 min	>60 min	IPC-TM-650
Moisture Absorption	0.1%	0.1%	IPC-TM-650 2.6.2.1
Max Operating Temp (UL)	130°C	130°C	UL Certified
UL Flammability	V-0	V-0	UL 94
UL File Number	E41625	E41625
IPC Classification	IPC-4103/17, IPC-4101/102	IPC-4103/17
RoHS	Compliant	Compliant
Peel Strength	0.79 N/mm (4.5 lb/in)	—	Standard copper
Thermal Conductivity	0.61 W/m·K	—

The T260 and T288 ratings of >60 minutes each confirm that I-Tera MT40 supports aggressive lead-free assembly profiles with substantial margin. For programs that involve multiple assembly passes or high-temperature rework, this is the thermal assurance that prevents the material from being the limiting factor.

Understanding the Multiple Dk Options in I-Tera MT40 RF/MW

The four Dk options (3.38, 3.45, 3.60, 3.75) in the RF/MW variant are one of I-Tera MT40’s most practically useful design enablers, and they’re often underutilized because engineers don’t immediately think about Dk as a design variable for RF circuits. Here’s why it matters.

In microstrip transmission lines, the physical width required to achieve a specific characteristic impedance (50 Ω, 75 Ω, or any other target) is an inverse function of the substrate Dk. A higher Dk gives you a physically narrower trace for the same impedance, because the electric field is more concentrated in the dielectric. A lower Dk requires a wider trace for the same impedance.

For RF circuit designers working on size, weight, and power (SWaP) constrained applications — aerospace electronic warfare, satellite communications payloads, UAV sensors — the ability to choose Dk 3.60 or 3.75 instead of 3.45 means smaller circuit area for the same transmission line network. The higher Dk values 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.

Conversely, for designs where trace width must be larger for manufacturing yield reasons (a board shop with 4-mil minimum feature size, for example), choosing Dk 3.38 widens the traces for a given impedance target. These are real design decisions that the multiple Dk options directly enable within a single qualified material family.

Full Product Availability and Construction Options

I-Tera MT40 HSD Standard Material Offering

Parameter	Available Options
Laminate thickness	2 to 24 mil (0.05 to 0.61 mm)
Standard copper foil	HVLP (VLP2) ≤2.5 µm Rz JIS
Alternate copper foil	Advanced RTF ≤2.5 µm Rz JIS
Special copper foil	Embedded resistor foil
Copper weight	½, 1, 2 oz (18, 35, 70 µm); heavier and thinner available
Prepreg	Tooling of panels; moisture barrier packaging
Glass fabric	Spread weave in both directions (all constructions)

I-Tera MT40 RF/MW Standard Material Offering

Parameter	Available Options
Laminate thickness	10, 20, 30, 60 mil (0.25, 0.51, 0.76, 1.5 mm)
Copper foil — standard	HTE Grade 3
Copper foil — low profile	HVLP (VLP2) ≤2.5 µm Rz JIS (1 oz and below standard)
Alternate foil	RTF (Reverse Treat Foil); Embedded resistor foil
Copper weight	½, 1, 2 oz (18, 35, 70 µm)
Available Dk grades	3.38, 3.45, 3.60, 3.75

Performance and Processing Feature Summary

Category	Attribute
Performance	CAF resistant
	Low moisture absorption (0.1%)
	6x 260°C reflow capable
	6x 288°C solder float capable
	Dk stable to W-band frequencies
	Spread weave glass — all constructions
Processing	FR-4 process compatible
	No special through-hole treatments required
	Multiple lamination cycles
	Multiple reflow cycles
	Dimensional stability
	Lead-free assembly compatible
Compliance	UL 94 V-0 (File E41625)
	IPC-4103/17; IPC-4101/102
	RoHS compliant

The “No Special Through-Hole Treatment” Processing Advantage

This processing attribute deserves a full explanation because it directly affects fabrication cost, shop availability, and program schedule in ways that Dk and Df numbers don’t capture.

PTFE-based microwave laminates — the materials I-Tera MT40 is positioned as a cost-effective alternative to — require sodium etch (sodium naphthalide or sodium ammonia) or plasma treatment of the hole walls after drilling but before electroless copper plating. PTFE is chemically inert, which makes it an excellent dielectric but means it doesn’t naturally bond to electroless copper. Without sodium etch or plasma treatment, through-hole plating adhesion is poor, and via reliability fails under thermal cycling.

Sodium naphthalide is toxic and requires specialized chemical handling and disposal. Plasma treatment requires vacuum chamber equipment. Both add cost and cycle time. More practically, many PCB fabrication shops — particularly regional shops that don’t specialize in microwave substrates — don’t have sodium etch or plasma treatment on their production lines for volume orders. This narrows the fabricator selection for PTFE designs to a subset of specialized shops, which reduces price competition and can create capacity constraints.

I-Tera MT40 eliminates that constraint. Because it is a thermoset resin-based material rather than a fluoropolymer, standard permanganate desmear is sufficient for hole wall preparation. Any PCB shop capable of processing I-Tera MT40’s thermal requirements (standard high-performance epoxy lamination conditions) can process I-Tera MT40’s through-holes with no additional investment in chemistry or equipment.

Processing Isola I-Tera MT40: Practical Guidance for Fabricators

Isola Group’s I-Tera MT40 laminates are fully cured and ready for processing. They share the same PCB manufacturing parameters as Tachyon 100G, which means any shop running Tachyon 100G has essentially already qualified the I-Tera MT40 process.

Lamination

The lamination cycle calls for 60 minutes at 200°C cure temperature. Use the full cycle for both subassembly and final lamination for assemblies ≥0.125″ (3.2 mm) total thickness. Apply pressure after vacuum dwell time; dual-stage pressing is common on complex constructions with difficult-to-fill features.

Stress relief bake cycles are not effective for reducing dimensional movement in high-performance laminates such as I-Tera MT40. The recommended approach is to characterize dimensional movement of unbaked laminate on your specific panel format and apply artwork compensation factors. Most movement will be in the grain direction of the laminate. Shrinkage is the typical net dimensional movement after etch, oxide, and lamination — due to relaxation of stresses induced during pressing.

Drilling

Relative to standard FR-4 parameters, use lower chiploads and cutting speeds to drill I-Tera MT40 printed circuit boards. Undercut drill geometries and high-helix tools are recommended to ensure effective resin debris removal. For thicker boards above 2.5 mm overall thickness and high layer counts, drill one high. Maximum hit count for drill diameters below 0.020″ is 1,000, and for diameters at or above 0.020″ the limit is 1,500 hits, subject to board geometry and stack height.

Boards with numerous 2 oz copper inner layers or coarse glass weave require more conservative drill parameters. When transitioning from standard FR-4 parameters on first run, the I-Tera MT40 processing guide drilling parameter table is the starting point — it should not be assumed that FR-4 drill parameters will produce acceptable hole quality.

Desmear

Standard chemical permanganate desmear at FR-4 processing parameters is the baseline. Two passes are recommended for high-reliability designs or boards exceeding 2.5 mm total thickness. No plasma treatment or sodium etch is required for I-Tera MT40 — this is both a cost advantage and a shop availability advantage over fluoropolymer-based alternatives.

Prepreg Handling and Storage

Handle all prepreg using clean gloves. If not handled properly, I-Tera MT40 prepreg will absorb moisture, which will lead to depressed Tg values, affect cure, and alter flow during lamination. Upon receipt, move all prepreg immediately to a controlled environment. Use FIFO inventory management. Do not vacuum seal the prepreg — store in original packaging with fresh desiccant, away from high radiation and intense UV sources.

For finished boards requiring long shelf life before high-temperature lead-free assembly, package in a Moisture Barrier Bag with a Humidity Indicator Card and adequate drying desiccant. Upon opening the MBB, process boards within 168 hours at shop floor conditions of ≤30°C/60% RH. Reseal opened MBB bags immediately after inspection.

I-Tera MT40 Within the Isola Laminate Portfolio

Understanding where I-Tera MT40 sits in the Isola lineup clarifies the selection logic for PCB engineers choosing between the Isola high-speed digital family members.

Cross-Portfolio Position Comparison

Material	Dk (10 GHz)	Df (10 GHz)	Tg	Halogen-Free	Key Differentiator
I-Tera MT40 (HSD)	3.45	0.0031	215°C	No	Multiple Dk options; HSD + RF/MW
I-Tera MT40 (RF/MW)	3.38–3.75	0.0028–0.0035	215°C	No	Dk 3.60/3.75 for miniaturization
Tachyon 100G	3.02	0.0021	215°C	No	Lowest Dk + Df in non-HF family
Astra MT77	3.00	0.0017	200°C	No	Best RF/MW; mmWave to 110 GHz
TerraGreen 400G	3.15	0.0017	200°C	Yes	Halogen-free, lower Df than I-Tera
I-Speed	3.45	0.0069	180°C	No	Cost-effective; 10–25 Gbps range
FR-4 (370HR)	3.95	0.018	180°C	No	General purpose

The positioning is clear when you read the table. I-Tera MT40 occupies the mid-tier between standard I-Speed (Df 0.0069) and premium Tachyon 100G (Df 0.0021). Its Dk 3.45 is the same as I-Speed, which means impedance calculations for existing I-Speed designs can migrate to I-Tera MT40 without trace width changes — only the loss performance changes.

The critical unique attribute of I-Tera MT40 is the multi-Dk RF/MW variant with Dk options up to 3.75. Neither Tachyon 100G nor Astra MT77 offers multiple Dk values. Both of those materials have a fixed Dk around 3.0, which sets the trace width for all impedance targets. I-Tera MT40 RF/MW at Dk 3.60 or 3.75 gives microwave designers the ability to narrow traces for a given impedance — a direct SWaP benefit in space-constrained military and aerospace designs.

I-Tera MT40 vs Tachyon 100G: When to Choose Which

This is the comparison that comes up most often in design reviews, and the decision framework is straightforward.

Choose Tachyon 100G when: the primary application is high-speed digital at 100 Gb/s and above, the channel loss budget is driving the specification, you need the lowest possible Dk (3.02) for the widest trace widths, and you’re not running RF/microwave content on the same board.

Choose I-Tera MT40 when: the design includes RF or microwave signal paths alongside high-speed digital, you need multiple Dk options to optimize trace geometry for specific impedance targets, cost efficiency at moderate data rates (25–50 Gbps) justifies Df 0.0031 rather than 0.0021, or the design requires the ability to miniaturize microwave structures using higher Dk grades.

Combined with a 215°C Tg and excellent thermal compatibility with materials like Astra MT77 and Tachyon 100G, I-Tera MT40 is often the material of choice for complex hybrid builds.

Hybrid PCB Builds: I-Tera MT40 With Astra MT77 and Tachyon 100G

This is where I-Tera MT40’s design value becomes most tangible for complex systems. Modern 5G base station hardware, military EW systems, and advanced automotive ADAS radar all require boards that combine digital signal processing, high-speed serial interfaces, and RF/microwave front-end circuits on the same multilayer PCB. Designing those boards as single-material constructions forces a materials compromise: use a low-loss material and pay RF-material prices for all layers, or use a more affordable HSD material and accept that the RF layers underperform.

The two materials deliver stable thermal performance with similar characteristics, including the same glass transition temperature (+200°C), to invite combination in production processes for mixed-signal circuits. The thermal compatibility Isola engineered between I-Tera MT40, Tachyon 100G, and Astra MT77 enables hybrid builds where different layers use the material most appropriate to the signal type on that layer, without the CTE mismatch problems that cause warpage and delamination in poorly matched hybrid stacks.

A Practical Hybrid Build Example

Consider a 5G Massive MIMO radio unit that combines a 56 Gbps backhaul interface, DDR5 memory, and a sub-6 GHz RF front-end. A viable hybrid stack might use I-Tera MT40 (HSD) on the digital signal routing layers (Dk 3.45 supports impedance targets across the digital signal bus with well-characterized properties at 28 Gbps) and I-Tera MT40 (RF/MW) at Dk 3.60 on the antenna feed network layers, with the higher Dk enabling narrower antenna feed traces in the constrained board area. Because both layers are I-Tera MT40, they use identical lamination cycles, identical press parameters, and identical desmear chemistry — simplifying the fabricator’s process enormously compared to a Tachyon 100G / Rogers hybrid.

For the highest-performance versions of this same board — where the HSD channels need Df 0.0021 rather than 0.0031 — the outer HSD layers could use Tachyon 100G, with the RF/MW layers using I-Tera MT40 RF/MW or Astra MT77. The CTE matching across this family means the hybrid lamination is stable.

Target Applications for Isola I-Tera MT40

The application fit for I-Tera MT40 is defined by its combination of moderate-to-low loss, multiple Dk options, W-band frequency stability, and FR-4 process compatibility without fluoropolymer through-hole treatments:

5G Base Station and RAN Equipment: Distributed Unit (DU) and Radio Unit (RU) boards, O-RAN system hardware, and 5G NR infrastructure where the board must carry both multi-gigabit digital interfaces and RF signal paths to antenna arrays. I-Tera MT40’s dual-use positioning (HSD and RF/MW in the same family) simplifies the material system for these inherently mixed-signal designs.

Aerospace and Defense Electronics: Radar front-end substrates, electronic warfare signal processing boards, satellite communication payloads, and avionics where the combination of W-band stability, SWaP optimization through higher Dk grades, and thermal reliability from -55 to +125°C is the specification. The absence of plasma or sodium etch requirements means more fabricators can support production without specialized equipment qualifications.

Automotive ADAS Radar and Telematics: 77 GHz radar front-end boards and telematics platform PCBs where the automotive operating temperature range (-40°C to +140°C in the RF/MW variant) aligns with actual deployed conditions. I-Tera MT40 supports the W-band frequency range directly applicable to automotive radar. Isola’s technical presentations specifically reference automotive safety systems as a target for I-Tera MT40’s hybrid circuit architecture.

Military and Aerospace Size/Weight/Power (SWaP) Designs: The Dk 3.60 and 3.75 grades of I-Tera MT40 RF/MW enable smaller microwave circuit footprints versus Dk 3.45. For radar transmitter/receiver modules, aircraft electronic countermeasure systems, and satellite payload subsystems where board area is constrained, the ability to specify higher Dk reduces the PCB real estate required for each RF function.

High-Speed Digital Infrastructure (25–50 Gbps Range): For designs where the channel data rate sits in the 25–50 Gbps per lane range and Df 0.0031 closes the loss budget, I-Tera MT40 provides the performance step up from I-Speed at a cost point lower than Tachyon 100G. Data center access switches, campus core networking equipment, and 100G enterprise NICs running at sub-100 Gbps aggregate per port often fall into this category.

Medical Imaging and Industrial Instrumentation: High-frequency ultrasound systems, industrial radar and level sensing, and test instrumentation where the Dk stability across temperature is required for consistent measurement performance and where the absence of exotic processing requirements supports lower manufacturing cost in smaller production volumes.

For fabrication support and material sourcing for ISOLA PCB laminates including I-Tera MT40, working with a fabricator experienced in high-performance epoxy laminate processing is the reliable path to achieving the material’s full frequency and thermal performance in the finished board.

Stack-Up Design Guidance for I-Tera MT40

Several practical notes for engineers designing with I-Tera MT40 for the first time or migrating from other laminates:

Dk selection depends on frequency and circuit geometry. For HSD designs, the nominal Dk 3.45 of I-Tera MT40 (HSD) matches I-Speed Dk, which means controlled impedance calculations from I-Speed designs can migrate directly without trace width recalculation — only the loss per unit length changes. For RF/MW designs, model your specific Dk option at your operating frequency using Isola’s Dk/Df tables, not the nominal value, since composite laminate Dk shifts slightly with resin content across construction options.

PIM (Passive Intermodulation) considerations for RF designs. Passive intermodulation is relevant for RF applications at high power levels, particularly base station antenna systems. PIM values for I-Tera MT40 are influenced by copper foil treatment roughness — PIM values presented in the datasheet were achieved with VLP-2 copper foil. If PIM is a specification requirement, confirm copper foil type with your fabricator and specify accordingly.

Artwork compensation. Stress relief bake cycles do not effectively reduce dimensional movement in I-Tera MT40. Characterize movement on unbaked laminate at your fabricator’s equipment before finalizing artwork compensation. Most movement occurs in the grain direction of the laminate.

Hybrid build CTE verification. Before finalizing a hybrid stack-up combining I-Tera MT40 with Tachyon 100G or Astra MT77, verify the specific CTE values for your construction combination with your fabricator and use Isola’s IsoStack tool to model the stack-up. Shared Tg values do not automatically guarantee compatible lamination cycles — confirm press cycle compatibility for the specific combination.

Useful Resources and Data Downloads

Resource	Type	Link
I-Tera MT40 (HSD) Product Page	Isola product page	isola-group.com/i-tera-mt40
I-Tera MT40 (RF/MW) Product Page	Isola product page	isola-group.com/i-tera-mt40-rfmw
I-Tera MT40 HSD Datasheet PDF	Official datasheet	isola-group.com (PDF)
I-Tera MT40 RF/MW Datasheet PDF	Official datasheet	isola-group.com (RF/MW PDF)
I-Tera MT40 Processing Guide	Fabrication guide PDF	isola-group.com (Processing)
I-Tera MT40 Dk/Df Tables	Frequency data PDF	isola-group.com (Dk/Df)
Tachyon 100G Product Page	Comparison material	isola-group.com/tachyon-100g
Astra MT77 Product Page	Hybrid build partner	isola-group.com/astra-mt77
IsoDesign / IsoStack Tools	Online stack-up tool	isola-group.com/design-tools
IPC-4103/17 and IPC-4101/102	IPC Standards	ipc.org
UL Product iQ (File E41625)	UL Certification DB	iq.ul.com
Isola EuMW 2022 Materials Article	Technical article	isola-group.com/eumw-2022

Frequently Asked Questions About Isola I-Tera MT40

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

Both variants share the same resin system, Tg (215°C), Td (360°C), processing parameters, and UL qualification. The differences are in construction and Dk options. The standard I-Tera MT40 is optimized for high-speed digital multilayer designs, available in 2 to 24 mil laminate thicknesses, and offered at the nominal Dk 3.45. The RF/MW variant is available in heavier constructions (10, 20, 30, 60 mil) suitable for microwave circuit geometries, and offers four Dk grades: 3.38, 3.45, 3.60, and 3.75. The multiple Dk options in the RF/MW variant directly support microwave circuit miniaturization — higher Dk grades narrow the transmission line traces required for a given impedance, reducing circuit area for SWaP-constrained designs. Both variants specify Df in the range of 0.0028–0.0035 depending on the specific construction.

2. Does Isola I-Tera MT40 require plasma treatment or sodium etch for through-hole processing?

No. This is one of I-Tera MT40’s primary manufacturing advantages over PTFE-based microwave laminates. I-Tera MT40 does not require any special through-hole treatments commonly needed when processing PTFE-based laminate materials. Standard permanganate chemical desmear is fully adequate for hole wall preparation before electroless copper plating, using the same process parameters as FR-4 and other high-performance epoxy materials. This eliminates the sodium naphthalide or plasma treatment steps that PTFE laminates require, which reduces process cost, removes the need for specialized chemistry or equipment, and broadens the pool of fabricators capable of processing the material.

3. How does the Dk stability “to W-band frequencies” affect real PCB designs?

W-band covers 75–110 GHz. I-Tera MT40’s Dk remaining stable from DC through W-band means the controlled impedance of transmission lines and the electrical length of resonant structures on I-Tera MT40 boards are consistent across this entire frequency range. For a radar transceiver board at 77 GHz (automotive ADAS radar) or a 5G small cell at 60 GHz (V-band ISM), the Dk value used in the design’s electromagnetic model at the operating frequency closely matches the actual material behavior. A material whose Dk rises significantly above 10 GHz would cause impedance deviations and resonance frequency shifts in designed circuit elements. The W-band stability is the specification that makes I-Tera MT40 useful for these applications rather than just for sub-10 GHz digital interfaces.

4. Can I-Tera MT40 be used in hybrid builds with Tachyon 100G or Astra MT77?

Yes. I-Tera MT40, Tachyon 100G, and Astra MT77 share compatible Tg values (200–215°C) and similar processing parameters. Both I-Tera MT40 and Tachyon 100G share the same PCB manufacturing parameters, and Isola has specifically developed these materials to be thermally compatible for hybrid multilayer constructions. Common hybrid build configurations include: I-Tera MT40 HSD on digital signal layers combined with I-Tera MT40 RF/MW on RF layers (same processing, different Dk), or I-Tera MT40 on mid-performance channels combined with Tachyon 100G on channels requiring Df 0.0021. Astra MT77 with I-Tera MT40 in the same stack serves designs where some layers need W-band RF stability (Astra) and others need cost-effective HSD performance (I-Tera). Always verify CTE compatibility and press cycle compatibility with your fabricator before finalizing a hybrid build design.

5. Is I-Tera MT40 an appropriate material for 100 Gbps SerDes channels?

It depends on the channel geometry. I-Tera MT40 with Df 0.0031 is a viable material for 100 Gbps channels where trace lengths are short and there is sufficient noise margin in the channel loss budget. For long backplane channels (>20 inches at 28 GHz) at 100 Gbps, Df 0.0031 typically results in total insertion loss that is too high for practical link budget closure without active retimers on every segment. In those cases, Tachyon 100G (Df 0.0021) or one of the TerraGreen 400G halogen-free grades is the more appropriate specification. The decision should be driven by running actual channel loss simulations with the I-Tera MT40 Dk/Df values at your specific trace lengths and operating frequencies — the headline Df comparison is the starting point, but the channel model with real geometry is the final arbiter.

Engineering Summary: Where Isola I-Tera MT40 Belongs in Your Material Hierarchy

Isola I-Tera MT40 occupies a unique position in the PCB materials landscape that no single competitor fully replicates: it is a very low-loss thermosetting material, FR-4 process compatible, with multiple Dk options that enable both high-speed digital and RF/microwave circuit design, processable on any shop that handles high-performance epoxy without fluoropolymer through-hole treatments, and thermally compatible with Isola’s adjacent premium materials for hybrid builds.

For programs that are purely high-speed digital above 100 Gbps and need the lowest possible loss, Tachyon 100G is the answer. For programs that are purely RF/microwave and require the absolute lowest loss at millimeter-wave frequencies, Astra MT77 is the answer. For everything between those extremes — designs that mix high-speed digital interfaces with RF front-ends, designs that need multiple impedance targets on the same board, designs where SWaP matters and Dk choice drives circuit area, designs where avoiding PTFE through-hole processing is a manufacturing or cost priority — I-Tera MT40 is the material that was designed specifically for that space.

For fabrication support and material sourcing across the full Isola laminate portfolio including I-Tera MT40, visit RayPCB’s ISOLA PCB resource page.