I-Tera MT40 PCB: PCB Design, PCB Manufacturing & High-Speed Applications

I-Tera MT40 PCB: PCB Design, PCB Manufacturing, High-Speed & RF Applications

As electronic systems continue to demand higher data rates, greater efficiency, lower signal loss, and improved reliability, advanced PCB materials have become increasingly important. Conventional FR-4 materials remain suitable for a wide range of applications, but demanding high-speed digital, RF, microwave, and high-frequency designs often require tighter control of dielectric properties and transmission losses.

I-Tera® MT40 from Isola is a very-low-loss laminate and prepreg system developed for high-speed digital and RF/microwave PCB applications. It combines a stable dielectric constant (Dk), low dissipation factor (Df), high thermal reliability, CAF resistance, and compatibility with conventional FR-4-style PCB manufacturing processes.

According to Isola, standard I-Tera MT40 has a typical Dk of 3.45, Df of 0.0031, Tg of 215°C, Td of 360°C, and thermal conductivity of 0.61 W/m·K. The material is designed to provide a practical alternative to PTFE and other specialized high-frequency materials while maintaining compatibility with conventional PCB processing.

This article examines I-Tera MT40’s electrical and thermal properties, manufacturing advantages, PCB Design considerations, and applications in high-speed computing, telecommunications, automotive electronics, medical systems, aerospace, and other advanced electronic products.

What Is I-Tera MT40?

I-Tera MT40 is a high-speed, very-low-loss laminate and prepreg material designed for demanding digital and RF/microwave printed circuit applications.

Unlike conventional PCB materials that may introduce greater dielectric loss at higher frequencies, MT40 provides a relatively low Df and stable dielectric behavior across a broad frequency and temperature range. This makes it useful for applications where signal integrity, impedance control, and transmission efficiency are critical.

Isola describes I-Tera MT40 as suitable for high-speed digital and RF/microwave PCB designs. Its stable Dk and low Df allow designers to develop controlled-impedance transmission structures without necessarily moving to PTFE-based manufacturing processes.

Another important advantage is process compatibility. MT40 can be processed using many conventional PCB manufacturing methods, including lamination, drilling, plating, soldering, and multilayer fabrication. Isola specifically identifies the material as FR-4 process compatible, multiple-reflow capable, and suitable for multiple lamination cycles.

Key I-Tera MT40 Material Properties

The following table summarizes representative properties of standard I-Tera MT40 based on Isola’s published technical information.

Property	Typical Value
Dielectric Constant (Dk)	3.45
Dissipation Factor (Df)	0.0031
Glass Transition Temperature (Tg)	215°C
Decomposition Temperature (Td)	360°C
Thermal Conductivity	0.61 W/m·K
X/Y-Axis CTE, Pre-Tg	12 ppm/°C
Z-Axis CTE, Pre-Tg	55 ppm/°C
Z-Axis CTE, Post-Tg	290 ppm/°C
Dielectric Breakdown	45.4 kV
Volume Resistivity	1.33 × 10⁷ MΩ·cm
Surface Resistivity	1.33 × 10⁵ MΩ
Moisture Absorption	0.1%
Flammability	UL 94 V-0
Thermal Conductivity Test	ASTM E1952

These are typical material values rather than guaranteed production values. Actual PCB performance depends on resin content, glass style, copper roughness, construction, fabrication tolerances, frequency, temperature, and the specific MT40 construction selected.

For RF/microwave configurations, Isola also lists MT40 variants with Dk values of approximately 3.38, 3.45, 3.60, and 3.75 and Df values ranging from 0.0028 to 0.0035 at 10 GHz, depending on the selected construction.

Major Characteristics of I-Tera MT40

Stable Dielectric Constant

One of the most important advantages of MT40 is its stable dielectric behavior.

For controlled-impedance PCB Design, Dk directly affects transmission-line impedance and propagation characteristics. A predictable dielectric constant helps engineers establish more reliable stackups and impedance targets.

Isola states that I-Tera MT40 maintains stable dielectric properties across a broad temperature and frequency range. The standard MT40 material is specified for stability from -55°C to +125°C up to W-band frequencies, while the RF/MW version has a different published temperature range depending on construction.

This stability is particularly valuable for:

High-speed differential pairs
RF transmission lines
Microwave circuits
Antenna feed networks
High-speed SerDes channels
Controlled-impedance multilayer PCBs

Very Low Dissipation Factor

The dissipation factor of standard MT40 is approximately 0.0031.

A lower Df generally means lower dielectric loss, particularly when transmission lines operate at higher frequencies. Reducing dielectric loss can help preserve signal amplitude and waveform quality across long electrical paths.

This characteristic makes MT40 attractive for demanding applications such as high-speed networking, telecommunications, RF equipment, radar-related electronics, and high-performance computing.

However, material Df is only one part of the total channel-loss budget. Copper roughness, conductor geometry, trace length, connector transitions, vias, glass weave effects, and other discontinuities can also influence high-speed signal performance.

High Thermal Reliability

MT40 has a typical Tg of 215°C and Td of 360°C in Isola’s current standard material data. The material also demonstrates strong thermal resistance during PCB processing.

This thermal performance is important for lead-free assembly and multilayer fabrication because modern PCBs may experience repeated thermal cycles during:

Lamination
Reflow soldering
Rework
Component assembly
Multiple PCB processing stages

A high Tg does not mean the PCB can continuously operate at that temperature. Instead, Tg indicates a major transition in the polymer system, while actual operating temperature must be determined from the complete design, reliability requirements, and applicable specifications.

CAF Resistance and Long-Term Reliability

Conductive anodic filament (CAF) is an important reliability concern in densely routed multilayer PCBs, particularly when moisture, electrical bias, and closely spaced conductive structures are present.

MT40 is identified by Isola as CAF resistant and suitable for demanding multilayer applications.

For high-density PCB Manufacturing, CAF resistance can be particularly important when a design includes:

Closely spaced vias
Fine-pitch BGA packages
High layer counts
Small dielectric spacing
High operating humidity
Long service life requirements

Material selection should still be combined with appropriate PCB fabrication controls, via quality, cleanliness, moisture management, and spacing requirements.

FR-4 Process Compatibility

One of MT40’s strongest manufacturing advantages is that it does not require the same specialized processing approach associated with many PTFE-based materials.

Isola identifies MT40 as FR-4 process compatible, multiple-reflow capable, and capable of supporting multiple lamination cycles.

This can reduce the manufacturing barrier for PCB manufacturers that already have conventional multilayer production capabilities.

The practical benefits may include:

Conventional lamination equipment
Standard multilayer PCB processing
Conventional drilling and plating
Standard solder mask processing
Standard SMT assembly workflows
Easier integration into existing manufacturing systems

I-Tera MT40 vs. Conventional FR-4

Traditional FR-4 remains one of the most widely used PCB materials because of its balanced cost, mechanical properties, electrical performance, and manufacturing availability.

However, as signal frequencies and data rates increase, dielectric loss and impedance stability become more important.

Characteristic	Conventional FR-4	I-Tera MT40
Typical Use	General-purpose electronics	High-speed and RF/microwave electronics
Dk	Material-dependent	3.45 typical
Df	Material-dependent and generally higher than MT40	0.0031 typical
Signal Loss	Application-dependent	Lower-loss architecture
Thermal Reliability	Material-dependent	Tg 215°C typical
High-Speed Applications	Moderate to high depending on grade	Specifically designed for high-speed applications
RF/Microwave Applications	Limited by material grade	Suitable
Manufacturing	Conventional PCB processes	FR-4 process compatible
Cost	Generally lower	Higher than standard FR-4
Design Control	Depends strongly on material grade	Improved dielectric predictability

The choice should not be based simply on whether a material has a lower Dk or Df. Engineers should evaluate the complete channel-loss budget, impedance requirements, operating temperature, stackup, copper roughness, fabrication tolerances, and total system cost.

I-Tera MT40 in PCB Design

Using MT40 successfully requires more than simply replacing an FR-4 material in an existing design.

Optimize the PCB Stackup

A controlled multilayer stackup is fundamental to high-speed and RF PCB performance.

The stackup should define:

Signal-layer locations
Ground-plane locations
Power-plane locations
Dielectric thickness
Copper thickness
Glass styles
Resin content
Controlled impedance
Via structures
Differential-pair geometry

For high-speed signals, placing a solid reference plane close to the signal layer can provide a predictable return path and help control electromagnetic coupling.

Control Trace Impedance

MT40’s predictable dielectric properties can support controlled-impedance designs.

Typical controlled structures include:

Microstrip
Stripline
Coplanar waveguide
Differential transmission lines
RF transmission lines

However, designers should not calculate impedance using Dk alone. Actual impedance depends on dielectric thickness, conductor width, copper thickness, copper roughness, geometry, and the specific material construction.

For demanding designs, the final stackup should be modeled using fabrication-specific material data and, where necessary, a field solver.

Optimize Via Structures

Vias can introduce discontinuities into high-speed channels.

As data rates increase, via capacitance, inductance, antipads, via stubs, and reference-plane transitions can affect insertion loss and return loss.

Depending on the design, engineers may consider:

Smaller via stubs
Backdrilling
Blind vias
Buried vias
Microvias
Optimized antipad geometry
Improved reference-plane transitions

These technologies can improve electrical performance but may also increase PCB Manufacturing complexity and cost.

Consider Glass-Weave Effects

Even with a low-loss laminate, high-speed differential pairs can experience skew or local dielectric variation associated with the glass/resin structure.

For particularly sensitive channels, designers should evaluate:

Trace orientation
Glass style
Resin distribution
Differential-pair symmetry
Routing density
Channel length

The appropriate strategy depends on the actual stackup and frequency range.

Thermal Management with MT40

Although MT40 offers a thermal conductivity of approximately 0.61 W/m·K, it should not be treated as a high-thermal-conductivity PCB substrate in the same category as dedicated metal-core or thermally enhanced ceramic materials.

Thermal performance still depends heavily on the complete PCB architecture.

Effective thermal strategies may include:

Large copper planes
Thermal vias
Copper pours
Heat spreaders
Thermal interface materials
Component placement optimization
External heatsinks
Adequate airflow
Short thermal paths

For high-power RF or digital systems, electrical and thermal design should be considered together.

I-Tera MT40 PCB Manufacturing Process

MT40 can be incorporated into a conventional multilayer PCB Manufacturing workflow.

A typical process may include:

Material selection and stackup definition
Inner-layer imaging
Inner-layer etching
AOI inspection
Layup and lamination
Mechanical or laser drilling where appropriate
Desmear and hole preparation
Electroless copper deposition
Copper electroplating
Outer-layer imaging and etching
Solder mask application
Surface finishing
Silkscreen printing
Routing or profiling
Electrical testing
Final inspection and reliability verification

The exact process depends on the layer count, via technology, copper thickness, surface finish, impedance requirements, and HDI construction.

Because MT40 is designed to be FR-4 process compatible, manufacturers can integrate it into established production infrastructure rather than adopting an entirely separate PTFE manufacturing process.

Manufacturing and Compliance Advantages

MT40 provides several advantages beyond its electrical performance.

Multiple Lamination and Reflow Capability

Modern high-density boards may require sequential lamination, multiple assembly operations, and lead-free reflow.

MT40 is identified as capable of multiple lamination cycles and multiple reflow processes, making it suitable for complex multilayer and HDI structures.

Dimensional Stability

Dimensional stability is important for fine-line routing, microvias, BGA registration, and multilayer alignment.

The material’s published X/Y-axis CTE is approximately 12 ppm/°C before Tg, supporting dimensional control when the complete manufacturing process is properly managed.

RoHS and UL Recognition

Isola lists MT40 as RoHS compliant and identifies UL File E41625. The standard material is also listed with UL 94 V-0 flammability performance and IPC-4103/17 and IPC-4101/102 recognition.

Compliance should always be confirmed against the specific material construction, revision, customer specification, and applicable end-product requirements.

Applications of I-Tera MT40

High-Speed Computing and Data Centers

Modern servers, switches, storage systems, and high-performance computing platforms rely on high-speed serial interfaces.

As channel frequencies and data rates increase, insertion loss, return loss, crosstalk, impedance discontinuities, and dielectric loss become increasingly important.

MT40 can therefore be considered for high-speed multilayer boards used in:

Network switches
Servers
Data storage
High-speed computing
Communication backplanes
High-speed interface boards

The material’s low Df and stable Dk can help engineers develop lower-loss transmission channels.

5G and Telecommunications

Telecommunications equipment frequently combines high-speed digital processing with RF and microwave circuits.

MT40 is particularly relevant to designs where low-loss transmission and stable dielectric properties are important, including RF front ends, communication equipment, wireless infrastructure, and other high-frequency systems.

The RF/MW version is specifically positioned by Isola for RF and microwave PCB applications.

Automotive Electronics

Modern vehicles increasingly rely on high-speed communication, radar-related electronics, ADAS, and electrified powertrain systems.

MT40 may be considered for automotive applications where electrical performance and thermal reliability are important.

Potential applications include:

Automotive radar
ADAS control electronics
High-speed vehicle networking
Infotainment systems
Communication modules
Electrified vehicle electronics

Automotive qualification should be evaluated at the complete product level rather than inferred from laminate properties alone.

Aerospace and Defense

Aerospace and defense electronics often require stable electrical performance over demanding environmental conditions.

Potential applications for low-loss high-speed laminates include:

Radar electronics
Avionics
Satellite communication
High-frequency instrumentation
Defense communication systems
Electronic sensing systems

In these applications, material selection must be combined with environmental qualification, mechanical reliability, thermal cycling, vibration, and applicable industry standards.

Medical Electronics

Medical imaging and diagnostic systems can require high-speed data acquisition and sensitive signal processing.

Potential applications include:

MRI-related electronics
CT systems
X-ray equipment
Ultrasound systems
Wireless medical devices
Diagnostic instrumentation

Isola’s medical and instrumentation materials portfolio includes MT40 among materials positioned for medical applications, including imaging and wireless systems.

How to Select MT40 for a PCB Project

Before selecting MT40, engineers should evaluate several factors.

1. Determine the Required Electrical Performance

Identify:

Maximum operating frequency
Data rate
Channel length
Insertion-loss budget
Return-loss requirements
Target impedance
Differential-pair requirements

2. Define the Stackup

The stackup should specify:

Number of layers
Dielectric thickness
Copper weight
Glass style
Resin content
Signal-reference-plane relationships

3. Evaluate Manufacturing Capability

Confirm that the PCB manufacturer can support:

Fine-line fabrication
Controlled impedance
HDI microvias
Sequential lamination
Backdrilling
Advanced inspection
Electrical testing

4. Consider Total Cost

MT40 can provide substantial electrical advantages, but material cost may be higher than standard FR-4.

Therefore, it should be used where the performance benefit justifies the additional material and fabrication cost.

5. Validate the Final PCB

Prototype testing should verify:

Impedance
Insertion loss
Return loss
Crosstalk
Thermal performance
Mechanical reliability
Electrical isolation
Environmental reliability

Why Choose a Professional PCB Manufacturing Partner?

Selecting the correct laminate is only one part of a successful high-speed PCB project.

A capable manufacturing partner should understand the relationship between material properties, stackup design, fabrication tolerances, impedance control, drilling, plating, solder mask, surface finish, and final electrical testing.

Kingda can support customers with PCB manufacturing and assembly requirements where material selection, high-speed performance, manufacturing reliability, and production consistency need to be considered together.

For MT40 projects, a manufacturing review should ideally begin before fabrication with:

DFM analysis
Stackup review
Impedance planning
Material verification
Drill and via review
Copper-thickness verification
Manufacturing-tolerance evaluation
Test-plan definition

This approach helps reduce redesigns and ensures that the selected laminate is properly translated into a manufacturable PCB structure.

Common Mistakes When Using I-Tera MT40

Treating MT40 as a Simple FR-4 Replacement

MT40 is FR-4 process compatible, but that does not mean every FR-4 stackup can simply be copied without modification.

The dielectric thickness, resin content, glass style, copper roughness, and impedance model must be reconsidered.

Focusing Only on Dk

A low or stable Dk is useful, but signal performance also depends on Df, conductor loss, copper roughness, geometry, vias, connectors, and return paths.

Ignoring Manufacturing Tolerances

A theoretically perfect impedance calculation may not match production results if dielectric thickness, trace width, copper thickness, and etching vary significantly.

Therefore, fabrication tolerances should be incorporated into the design from the beginning.

Assuming Low Loss Eliminates All Signal-Integrity Problems

MT40 can reduce dielectric loss, but it cannot automatically eliminate:

Crosstalk
Reflections
Via discontinuities
Poor return paths
Connector losses
Ground discontinuities
EMI problems

Material selection and PCB Design must work together.

I-Tera MT40 vs. PTFE: Which Should You Choose?

MT40 is often positioned as a cost-effective alternative to PTFE and other commercial microwave and high-speed laminate materials.

However, the best material depends on the application.

MT40 can be attractive when a project requires:

Low dielectric loss
Stable dielectric properties
High-speed digital performance
RF/microwave capability
Conventional PCB processing
Multilayer construction
Multiple reflow cycles
Reasonable manufacturing complexity

PTFE-based materials may still be preferred for specialized microwave designs where extremely low loss or specific RF performance characteristics justify more specialized processing.

The correct selection should therefore be based on frequency, loss budget, impedance requirements, thermal environment, mechanical constraints, fabrication capability, and cost.

Conclusion

I-Tera MT40 is a high-performance PCB laminate and prepreg system designed for demanding high-speed digital and RF/microwave applications. Its combination of approximately 3.45 Dk, 0.0031 Df, 215°C Tg, 360°C Td, CAF resistance, and FR-4 process compatibility makes it an attractive option for advanced PCB applications.

For engineers working on high-speed networking, telecommunications, automotive electronics, aerospace systems, medical equipment, and other demanding electronic platforms, MT40 can provide a useful balance between electrical performance and manufacturability.

The most important point is that material selection should not be isolated from PCB Design and PCB Manufacturing. Stackup construction, impedance control, signal routing, via design, copper roughness, fabrication tolerances, thermal management, and final testing all contribute to actual PCB performance.

When these factors are considered together, MT40 can help manufacturers develop reliable, low-loss, high-speed circuit boards without requiring the highly specialized processing often associated with PTFE-based materials.

Article Summary

I-Tera MT40 is a very-low-loss laminate and prepreg material developed for high-speed digital and RF/microwave PCB applications. Its stable dielectric characteristics, low dissipation factor, high Tg, high Td, CAF resistance, and FR-4 process compatibility make it suitable for demanding multilayer PCB applications. For successful implementation, engineers should combine appropriate material selection with optimized stackup design, controlled impedance, high-speed routing, thermal management, DFM analysis, and comprehensive electrical testing.