Isola Astra MT77 PCB Material: Ultra Low Loss RF/Microwave Laminate for Millimeter Wave and Automotive Radar

The history of RF and microwave PCB material selection has been a long negotiation between performance and manufacturability. PTFE-based laminates — the materials that dominated high-frequency PCB design for decades — gave circuit designers the low dielectric loss and Dk stability they needed at GHz frequencies, but came with a manufacturing tax that never fully disappeared: special drill bits, plasma desmear equipment for through-hole preparation, dimensional instability under lamination pressure, and a limited pool of qualified PCB fabricators willing to take on the material. Every RF engineer who’s tried to add PTFE layers to a mixed-signal hybrid build knows the headache.

Isola Astra MT77 arrived at IEEE IMS 2019 as Isola’s answer to that trade-off — a laminate that delivers electrical performance traditionally associated with ceramic-filled PTFE systems without requiring a single PTFE-specific fabrication step. Since its introduction, it has become the benchmark material for 77 GHz automotive radar PCBs, 5G mmWave base station antenna feed networks, airborne radar systems, and satellite communications hardware where standard FR-4 processes fail and PTFE is simply too expensive and too difficult to manufacture reliably at volume.

What Is Isola Astra MT77?

Isola Astra MT77 is an ultra-low loss RF/microwave laminate and prepreg classified by Isola as an Ultra Low Loss, RF/MW Laminate and Prepreg. It is the flagship material in Isola’s RF and microwave material portfolio, sitting above I-Tera MT40 on loss performance and competing directly with ceramic-filled PTFE systems on electrical properties while retaining full FR-4 process compatibility.

The product was formally introduced at the IEEE Microwave Theory and Techniques Society’s IMS Microwave Week in 2019, targeted specifically at the rapidly growing mmWave application segment driven by automotive ADAS radar at 77 GHz and 5G NR frequency range 2 (FR2) deployments. In the years since, Isola has presented Astra MT77 at IMS and IPC APEX exhibitions as its leading material for circuits operating to 100 GHz and beyond.

The “MT” designation means “Multi-Temperature” — the same naming convention used in I-Tera MT40 — reflecting the material’s defining characteristic: Dk and Df that remain genuinely constant across wide temperature and frequency ranges. The “77” references 77 GHz, the automotive radar frequency where the material first proved its commercial value and where it remains the dominant specification among ADAS-focused PCB designers.

Isola’s own technical description is precise: Astra MT77 enables RF/MW designers to get similar electrical performance traditionally associated with ceramic-filled PTFE systems, with ease of manufacturing due to its woven glass cloth reinforcement that creates excellent dimensional stability.

Isola Astra MT77 Complete Technical Specifications

Every RF/microwave design begins and ends with the electrical properties at operating frequency. These are the published values from Isola’s current datasheets.

Core Electrical Properties

Parameter	Value	Test Frequency	Notes
Dielectric Constant (Dk)	3.00	2 GHz (z-axis)	Bereskin Stripline
Dielectric Constant (Dk)	3.00	10 GHz (z-axis)	Bereskin Stripline
Dissipation Factor (Df)	0.0017	2 GHz	IPC-TM-650
Dissipation Factor (Df)	0.0017	10 GHz	IPC-TM-650
Df Tolerance	±0.0005	—	Design margin
Dk Stability vs. Temperature	Stable −40°C to +140°C	W-band	—
Dk Stability vs. Frequency	Constant at W-band	DC to 110 GHz+	—

The Dk of 3.00 is perfectly consistent between 2 GHz and 10 GHz — not approximately flat, not “nominally constant,” but genuinely the same value measured through the z-axis of the material at both test frequencies. Astra MT77 features the low loss desirable for mmWave signals, with a Df of typically 0.0017 at 10 GHz, and it has Dk that is consistent with frequency — 3.0 in the z-axis at both 2 and 10 GHz — and with temperature from −40°C to +140°C.

That Dk consistency with frequency is the key differentiator over high-speed digital materials like Tachyon 100G, which shows Dk decreasing slightly with frequency from 3.04 at 2 GHz to 3.02 at 10 GHz. For mmWave circuits where a resonant element’s physical dimensions are designed to exactly one-quarter or one-half of the signal wavelength at operating frequency, a Dk that shifts with frequency causes the circuit’s resonant frequency to drift away from the design target — a dispersion error that becomes increasingly significant as operating frequency climbs toward 77 GHz and beyond.

Thermal and Mechanical Properties

Parameter	Value	Test Method
Glass Transition Temperature (Tg)	200°C	DSC
Decomposition Temperature (Td)	360°C	TGA @ 5% wt. loss
Z-axis CTE (total, 55–288°C)	2.9%	IPC-TM-650
X/Y-axis CTE (pre-Tg)	12 ppm/°C	IPC-TM-650
Thermal Conductivity	—	ASTM E1952
Moisture Absorption	0.1%	IPC-TM-650
Peel Strength (1 oz copper)	5.7 lb/inch	IPC-TM-650 2.4.8C
Flammability	UL94 V-0	UL94

Industry Certifications and Compliance

Standard / Attribute	Status
UL File Number	E41625
RoHS	Compliant
UL94 Flammability	V-0
Lead-Free Assembly	Compatible
IPC-4103 Slash Sheet	/17
HDI / Microvia Compatible	Yes
Multiple Lamination Cycles	Supported
FR-4 Process Compatible	Yes
Plasma Desmear Required	No

Material Availability

Form	Specification
Laminate thicknesses	2.5, 5, 7.5, 10, 12.5, 15, 20, 30, 60 mil (0.064 to 1.52 mm)
Prepreg	Panel or roll form; tooling of prepreg panels available
Copper foil type	HVLP (VLP2) ≤2.0 µm Rz JIS standard
Copper weights	½ oz, 1 oz (18, 35 µm); thinner available
Glass fabric	Square and spread weave; square weave standard
Availability	Standard (commonly available) and Alternate (available, not stocked)

Why FR-4 Process Compatibility Is Astra MT77’s Defining Advantage

Any RF engineer who has worked with PTFE-based laminates understands the manufacturing premium they carry. That premium isn’t just material cost — it’s the complete ecosystem of specialized processing that PTFE requires.

H3: No Plasma Desmear Required

Standard PTFE laminates are chemically inert at their surface. After drilling, the PTFE residue smeared across the drill hole wall (resin smear) doesn’t bond to electroless copper without aggressive surface activation — typically plasma activation using CF4/O2 chemistry, or sodium naphthalene etching. Both processes require dedicated equipment, create chemical waste streams, add process steps, and introduce variability that affects via reliability.

Astra MT77 eliminates the need for plasma desmear because its woven glass cloth reinforced resin matrix provides sufficient surface chemistry for copper bonding through standard wet-chemical desmear processes. Standard wet chemical and plasma desmear can be used with no plasma activation of the surface required for successful copper deposition or soldermask application. This single fact expands the pool of qualified PCB fabricators from “handful of PTFE specialists” to “any competent multilayer PCB fab with controlled impedance capability.”

H3: Reduced Drill Wear — No Ceramic Filler

Ceramic-filled PTFE materials — Rogers RO3003, for example — achieve their low Dk through ceramic particulate loading. Ceramic particles are abrasive, and they rapidly dull PCB drill bits, reducing hit counts and increasing tooling costs. On high-volume automotive radar PCBs, drilling cost per unit is a meaningful production economics factor.

The lack of ceramic filler in the Astra MT77 resin matrix makes mechanical drilling a straightforward process and allows for extended hit counts without the need to resharpen drill bits, significantly reducing processing costs. For programs with annual volumes in the hundreds of thousands of boards — the production volumes realistic for automotive ADAS hardware — this drill wear advantage translates directly to manufacturing cost competitiveness.

H3: Dimensional Stability from Woven Glass Reinforcement

PTFE laminates are mechanically soft. Under the hydrostatic pressure of a lamination press, PTFE can creep, and panel-to-panel thickness uniformity is harder to control than in glass-reinforced systems. This creates challenges for controlled-impedance manufacturing on multi-layer boards where dielectric thickness tolerance directly drives impedance tolerance.

Astra MT77’s woven glass cloth reinforcement provides dimensional stability that is very good and repeatable because of the weave style — square and spread — meaning the impact from the fiber weave is negligible even at high frequencies. Woven glass inherently resists creep under lamination pressure, maintaining tighter thickness tolerances than PTFE alternatives and supporting more consistent controlled-impedance results across a production run.

H3: Shorter Lamination Cycle vs. PTFE

PTFE lamination requires specialized press temperature and pressure profiles, often with extended dwell times at temperature to achieve full consolidation without void formation. Astra MT77’s processing advantages include shorter lamination cycles — closer to standard FR-4 press parameters than PTFE, reducing cycle time and improving throughput on shared lamination lines.

The Core Electrical Physics: Why Dk 3.00 and Df 0.0017 Matter at 77 GHz

H4: Absolute Loss at 77 GHz — The Insertion Loss Budget

At 77 GHz in the W-band, skin depth in copper is approximately 0.24 µm. Conductor losses dominate at these frequencies, and substrate dielectric loss becomes a significant secondary contributor. With a Df of 0.0017, the dielectric contribution to insertion loss on a 50-ohm microstrip trace at 77 GHz is approximately 0.7–0.9 dB/cm — well below what would be acceptable on Rogers RO4350B (Df 0.0037, roughly 2× higher loss). For a 77 GHz patch antenna feed network with 5–8 cm of total trace length, that Df difference can mean 4–6 dB of system insertion loss budget — the difference between a radar system that detects objects at 250 meters and one that struggles at 150 meters.

H4: Dk Stability vs. Temperature — Critical for Automotive ADAS

Automotive ADAS radar systems operate over an ambient temperature range of approximately −40°C to +85°C under the hood, and the PCB substrate temperature can swing even wider during cold start and extreme duty cycles. Resonant RF structures — patch antennas, feeding networks, filter circuits — have resonant frequencies that are inversely proportional to the square root of the substrate Dk. If Dk drifts with temperature, the resonant frequency drifts, and radar performance degrades at temperature extremes.

Astra MT77 features a Dk that is stable between −40°C and +140°C — the full automotive operating temperature range with significant margin on the high end. This temperature stability is documented to W-band frequencies, meaning the material doesn’t just hold Dk at low frequencies while degrading at 77 GHz. For automotive OEM qualification programs where temperature-corner testing at −40°C and +125°C is mandatory, this stability is the specification that enables the board to pass without derating or redesign at temperature extremes.

H4: Frequency Dispersion — The mmWave Design Advantage

In standard FR-4 and even many low-loss materials, Dk decreases as frequency increases. This dispersion creates a phase velocity that is frequency-dependent — different frequency components of a broadband pulse travel at different speeds through the substrate. For narrowband mmWave circuits like 77 GHz FMCW radar, dispersion is less of an issue because the operating bandwidth is relatively narrow (typically 500 MHz to 4 GHz). But for wideband phased array systems, V-band (57–64 GHz) communications, and W-band sensing systems with instantaneous bandwidths of 10+ GHz, substrate dispersion causes phase distortion that degrades system performance.

Astra MT77’s Dk of 3.00 is constant from DC to W-band and beyond — the flattest frequency response available in any FR-4-process-compatible laminate, and competitive with the best PTFE materials for broadband phase linearity.

Target Applications for Isola Astra MT77

H3: Automotive ADAS Radar — 77 GHz and 79 GHz

Astra MT77’s primary design target from day one has been automotive radar, and it is the dominant specification for 77 GHz FMCW radar PCBs across the major Tier 1 ADAS suppliers. Key automotive applications include long-range adaptive cruise control (ACC), pre-crash braking systems, blind spot detection, lane departure warning, and stop-and-go (congestion assist) systems.

The automotive electronics qualification requirements are among the most rigorous in any commercial market: AEC-Q standards, IATF 16949 manufacturing qualification, −40°C to +125°C operating range, 10–15 year design life, and vibration and shock resistance that field electronics don’t face. Astra MT77’s Dk stability across −40°C to +140°C, Tg of 200°C for lead-free assembly compatibility, and glass-reinforced dimensional stability all directly address the thermal and mechanical requirements of automotive radar PCB qualification programs.

H3: 5G mmWave Infrastructure — FR2 Band Base Stations

5G NR Frequency Range 2 (FR2) uses mmWave spectrum in the 24–40 GHz bands (and higher in some national allocations). Massive MIMO antenna arrays and active antenna unit (AAU) boards for FR2 deployment are natural applications for Astra MT77. The antenna element feed networks, beamforming circuits, and T/R module substrates in FR2 massive MIMO hardware require low substrate loss at 28 GHz and 39 GHz to achieve the link budget and array efficiency targets that make mmWave 5G viable.

Astra MT77 is specifically recommended for 5G mmWave base stations and phased array antennas because the ultra-low Df of 0.0017 combined with Dk stability from −40°C to +140°C makes it ideal for the most demanding RF applications. For base station equipment designed for outdoor installation with operating temperature requirements from −40°C to +65°C ambient, the Astra MT77’s temperature stability covers the full deployment range.

H3: Aerospace and Military Radar — Airborne and Ground-Based Systems

Airborne radar systems — fire control radar, synthetic aperture radar (SAR), and electronic warfare support (ESM) antennas — operate in the Ku-band (12–18 GHz), Ka-band (26–40 GHz), and W-band (75–110 GHz). Ground-based military radar covers similar frequency ranges. These systems require substrate materials with PTFE-class electrical performance but the dimensional stability and manufacturability needed for high-layer-count, high-density PCB constructions.

Astra MT77 has become an established choice across aerospace and military radar hardware for exactly this reason. It maintains consistent electrical and mechanical attributes across wide operating temperature ranges in support of commercial and military applications at mmWave frequencies, including automotive ADAS radars and airborne radar systems. The combination of PTFE-competitive Df and standard fabrication compatibility makes military specification board construction straightforward at the substrate level.

H3: Satellite Communications — Low Earth Orbit and VSAT

Satellite phased array antennas for Low Earth Orbit (LEOS) constellations and VSAT terminals operate at Ku-band (10.7–12.75 GHz receive, 14–14.5 GHz transmit) and Ka-band (17.7–21.2 GHz receive, 27.5–31 GHz transmit). Astra MT77 is consistently cited among circuit materials suitable for LEOS system configurations, specifically for its Tachyon 100G, I-Tera MT40, Astra MT77, and 370HR combination covering all signal types from digital processing through RF front-ends.

For ISOLA PCB fabrication of satellite communication hardware, Astra MT77 provides the substrate stability needed for phased array aperture boards where hundreds or thousands of antenna elements must maintain consistent impedance and phase characteristics simultaneously — requirements where even small Dk variations across the panel translate to array beam pattern errors.

H3: Hybrid RF/Digital PCB Constructions

One of Astra MT77’s most practically valuable capabilities is its documented thermal and mechanical compatibility with Tachyon 100G and I-Tera MT40 for hybrid PCB constructions. Astra MT77 and Tachyon 100G are good candidates for hybrid PCBs where one material holds RF/microwave circuits and the other handles HSD circuits — this thermal compatibility is documented explicitly by Isola and reported in Microwaves & RF magazine.

In a 5G base station AAU board, the typical architecture has a digital baseband section running 25–56 Gbaud SerDes interfaces (Tachyon 100G or I-Tera MT40 territory) feeding into an RF analog section at 24–39 GHz (Astra MT77 territory). Combining both materials in a single board requires matched CTE profiles to prevent warpage and delamination at the material interface. Astra MT77 and Tachyon 100G’s similar CTE characteristics across −55 to +125°C specifically enable this hybrid construction, which is standard engineering practice in 5G AAU design.

Isola Astra MT77 vs. Competing Materials

This is the comparison RF engineers need when defending a material specification to a procurement team or qualifying an alternative.

Material	Manufacturer	Dk (10 GHz)	Df (10 GHz)	Tg	FR-4 Process	Ceramic Filler	W-band Stable
Astra MT77	Isola	3.00	0.0017	200°C	Yes	No	Yes
I-Tera MT40 (RF/MW)	Isola	3.45	0.0031	200°C	Yes	No	Yes
Tachyon 100G	Isola	3.02	0.0021	215°C	Yes	No	Partial
Rogers RO4350B	Rogers	3.48	0.0037	280°C	Partial	No	Limited
Rogers RO3003	Rogers	3.00	0.0010	—	No (PTFE)	Yes	Yes
Rogers RO3010	Rogers	10.2	0.0022	—	No (PTFE)	Yes	Yes
Taconic TLY-5	Taconic	2.17	0.0009	—	No (PTFE)	No	Yes

Against Rogers RO4350B — the dominant reference standard for FR-4-process-compatible RF laminates for many years — Astra MT77 delivers dramatically lower Df (0.0017 versus 0.0037 at 10 GHz). Both materials avoid PTFE processing, but Astra MT77’s lower Dk (3.00 versus 3.48) also provides wider trace geometries for a given impedance target and lower substrate contribution to insertion loss at mmWave frequencies.

Against Rogers RO3003 — a PTFE/ceramic material at Dk 3.00 that is the most common direct competitor — Astra MT77’s Df of 0.0017 versus RO3003’s 0.0010 represents a modest but real loss penalty in exchange for the complete elimination of PTFE process requirements. For the vast majority of automotive radar and 5G FR2 applications where RO3003 has historically been specified, Astra MT77 provides adequate or better electrical performance with manufacturing economics that scale more favorably in high-volume automotive and telecom production.

Stackup Design and Processing Guidelines for Astra MT77

H4: Use Exact Dk from Construction Tables

The Dk of 3.00 is the nominal z-axis value at 2 and 10 GHz. For precise microstrip and stripline filter and resonator design, use the construction-level Dk values from Isola’s published Dk/Df tables. Astra MT77 constructions range from 2.5 mil to 60 mil core thicknesses, each with specific resin content percentages that produce slightly different composite Dk values. For a 77 GHz patch antenna where resonant frequency accuracy of better than 1% is required, using the nominal Dk of 3.00 rather than the construction-specific value can produce a frequency error of several hundred MHz.

H4: HVLP Copper Is Non-Optional at mmWave Frequencies

At 77 GHz, the skin depth in copper is approximately 0.24 µm. Standard copper foil with 6–8 µm Rz roughness peaks presents surface variations that are 25–33× the skin depth — a severe conductor loss amplifier at this frequency. Astra MT77 standard copper offering is HVLP (VLP2) at ≤2.0 µm Rz JIS. For any design operating above 20 GHz, HVLP copper is the only appropriate specification. The peel strength of HVLP copper on Astra MT77 (5.7 lb/inch for 1 oz copper) is documented in the datasheet, confirming that the ultra-smooth foil bonds reliably to the substrate without the roughness features that standard copper relies on for mechanical adhesion.

H4: Hybrid Stackup Planning with Tachyon 100G or I-Tera MT40

For hybrid constructions combining Astra MT77 RF layers with Tachyon 100G or I-Tera MT40 digital layers, confirm the CTE compatibility and press cycle parameters with your fabricator before finalizing the stackup. The thermal compatibility between Astra MT77 and Tachyon 100G is documented, but specific core and prepreg pairings at specific thicknesses need fabricator validation against their specific lamination process parameters to ensure the hybrid construction stays flat and void-free after pressing.

H4: Via Design — Laser vs. Mechanical Drilling Trade-offs

At sub-3 mm substrate thicknesses common in mmWave PCBs (typical Astra MT77 core thicknesses for 77 GHz work are 5–15 mil), standard mechanical drilling is appropriate and benefits from the reduced drill wear compared to ceramic-filled alternatives. For microvias in sequential HDI constructions, laser ablation works normally with Astra MT77 given its glass-reinforced construction. For mmWave circuits where via stubs create resonances in the signal bandwidth (particularly on thicker substrate constructions at 77 GHz), back-drilling or via-in-pad structures may be required — plan these before the layout begins.

Useful Resources for Isola Astra MT77

• Isola Astra MT77 Official Product Page — Product overview, thickness options, and documentation downloads
• Astra MT77 Datasheet PDF — Full electrical, thermal, and mechanical property tables
• Astra MT77 Dk/Df Construction Tables PDF — Per-construction Dk/Df values at multiple frequencies
• Isola RF/Microwave Materials Portfolio — Astra MT77 alongside I-Tera MT40 (RF/MW), IS680, IS680 AG in cross-product comparison
• Isola Technical Blog: PTFE Performance Without the Hassle — Isola’s own detailed comparison of Astra MT77 vs. ceramic-filled PTFE processing
• Isola Technical Blog: HSD vs. mmWave Material Differences — Deep dive on Astra MT77 vs. Tachyon 100G for hybrid PCB design
• Isola IsoStack Stackup Design Tool — Free online tool for Astra MT77 stackup modeling with construction-level Dk values
• ISOLA PCB Material Selection Guide at PCBSync — Practical Isola material selection guidance covering Astra MT77’s full application context
• Microwave Journal — IMS2023 Isola Coverage — Independent technical reporting on Astra MT77 at mmWave
• Microwaves & RF — PCB Materials for Higher Frequency Circuits — Industry technical analysis of Astra MT77 vs. Tachyon 100G and I-Tera MT40

Frequently Asked Questions About Isola Astra MT77

FAQ 1: What makes Isola Astra MT77 a genuine PTFE alternative rather than just a marketing claim?

The claim has substance behind it. PTFE-based materials like Rogers RO3003 achieve Dk 3.00 and Df 0.0010 at 10 GHz — legitimately lower Df than Astra MT77’s 0.0017. The claim Isola makes is “similar performance,” not “identical performance.” For the vast majority of automotive radar and 5G FR2 applications that specify RO3003 for its low Dk and low Df, Astra MT77’s Df of 0.0017 provides adequate or better electrical performance. The Df gap between RO3003 (0.0010) and Astra MT77 (0.0017) is 0.0007 — which on a typical 77 GHz radar board with 6 cm of microstrip transmission line represents less than 0.5 dB of additional insertion loss. That half-dB trades against: no plasma desmear equipment, standard drill bits, FR-4 compatible press cycles, expanded fabricator pool, and significantly lower manufacturing cost. For almost all volume automotive radar programs, that trade is solidly in Astra MT77’s favor.

FAQ 2: Can Isola Astra MT77 be processed in a standard multilayer PCB fabrication facility?

Yes, with the important qualification that the facility must have controlled-impedance manufacturing capability for mmWave work. Standard drilling equipment, standard aqueous desmear chemistry, standard lamination press cycles with appropriate temperature profiles, and standard copper plating chemistry all work with Astra MT77. The specific processing advantages documented for the material include no plasma desmear required, shorter lamination cycles, reduced drill wear compared to ceramic-filled alternatives, and good flow and fill characteristics. A PCB fabricator running FR-4 multilayer production who wants to add Astra MT77 to their capabilities needs controlled-impedance process control and RF-appropriate test capability (vector network analyzer or TDR for impedance verification) — not specialized PTFE equipment.

FAQ 3: What is the maximum frequency Astra MT77 can support?

Isola documents Astra MT77 for circuit applications to frequencies at 100 GHz and higher. The material maintains stable Dk from DC to W-band (75–110 GHz), which is the documented frequency range for automotive radar at 79 GHz, military W-band radar systems, and high-frequency communications. The material has also been discussed for photonics applications at even higher frequencies. In practice, the upper frequency limit of a circuit built on Astra MT77 is determined by the conductor geometry at the operating frequency and the fabrication capability of the board shop — not by an inherent material frequency limit.

FAQ 4: How does Astra MT77 compare specifically to Rogers RO4350B, which is widely qualified in existing programs?

Rogers RO4350B has Dk 3.48 and Df 0.0037 at 10 GHz. Astra MT77 has Dk 3.00 and Df 0.0017 at 10 GHz. The Dk difference (3.00 vs. 3.48) means Astra MT77 gives wider traces for the same impedance target, which reduces conductor loss and makes fine-geometry fabrication more tolerant. The Df difference (0.0017 vs. 0.0037) means Astra MT77 has approximately 54% lower dielectric loss — at 77 GHz, the dielectric loss difference between the two materials on a typical circuit is significant and measurable. For designs being done on RO4350B that must also function at 28 GHz, 60 GHz, or 77 GHz, Astra MT77 will typically provide 2–4 dB better insertion loss performance on equivalent transmission line geometries. The transition from RO4350B to Astra MT77 does require new impedance modeling (lower Dk means different trace widths) and board re-qualification at the fabricator, but delivers meaningful RF performance improvement in return.

FAQ 5: Is Astra MT77 appropriate for use in digital layers of a hybrid board, or is it strictly an RF material?

Astra MT77 is primarily an RF/microwave material — it’s classified by Isola as an RF/MW laminate, not as High Speed Digital. Its Dk of 3.00 and Df of 0.0017 are excellent for RF circuits, but it is not the appropriate choice for high-speed digital SerDes lanes where bandwidth up to 100 Gbps is needed. For hybrid boards combining both signal types, the standard Isola approach is Astra MT77 on the RF layers and Tachyon 100G or I-Tera MT40 on the digital layers — using each material where its properties are most relevant. The CTE compatibility between Astra MT77 and Tachyon 100G is specifically engineered to enable this hybrid construction. Using Astra MT77 throughout a hybrid board for cost simplification would over-specify the digital sections and potentially under-specify their thermal requirements given Astra MT77’s Tg of 200°C versus Tachyon 100G’s Tg of 215°C.

The Case for Astra MT77 in Your Next RF Design

Isola Astra MT77 has earned its position as the benchmark material for 77 GHz automotive radar and mmWave RF circuits by doing what no material before it convincingly achieved: delivering ceramic-filled PTFE electrical performance — Dk 3.00 constant to W-band, Df 0.0017 at 10 GHz, temperature stability from −40°C to +140°C — through a standard FR-4 manufacturing process with no plasma desmear, no ceramic abrasion of drill bits, and excellent dimensional stability from woven glass reinforcement.

For engineers who have been specifying PTFE materials because they assumed no FR-4-compatible alternative could match the loss performance at 77 GHz, Astra MT77 challenges that assumption with measured insertion loss data. For engineers already using RO4350B who need to push circuit frequency up to 28 GHz, 60 GHz, or 77 GHz, Astra MT77 offers a material upgrade path that stays on the same FR-4 manufacturing infrastructure their fabs already run. And for programs combining mmWave RF and high-speed digital in the same assembly — 5G AAU boards, radar signal processors, satellite modems — Astra MT77’s proven CTE compatibility with Tachyon 100G makes the hybrid construction tractable rather than heroic.