Isola Astra® MT77 is an ultra-low-loss laminate and prepreg system for RF, microwave and millimeter-wave printed circuits. The official datasheet lists a typical Dk of 3.00 and Df of 0.0017 at both 2GHz and 10GHz, plus stable dielectric behavior across a broad frequency and temperature range. Those headline numbers make MT77 attractive for antennas and automotive radar, but they do not define a manufacturable PCB by themselves.
At QFPCB, we review the exact core or prepreg construction, copper profile, trace geometry, dielectric thickness, bonding plan and verification method before confirming an MT77 stackup. For high-frequency materials, our supported scope is a reviewed high-frequency hybrid stackup or mechanically drilled blind-via stackup—not HDI or Any-Layer HDI fabrication.
What is Isola Astra MT77?
Astra MT77 is a thermoset, very-low-loss RF/microwave material positioned by Isola as an alternative to PTFE and other commercial microwave laminates. Isola states that its Dk remains stable from -40°C to +140°C up to W-band frequencies. Typical applications include automotive long-range antennas and radar functions such as adaptive cruise control, pre-crash sensing, blind-spot detection and lane-departure warning.
Unlike PTFE laminates, MT77 is described as FR-4 process compatible. The datasheet lists reduced drill wear, no required plasma desmear, good flow and fill, dimensional stability and multiple lamination cycles. These are material-processing attributes; the finished PCB process still requires factory-specific qualification.
Astra MT77 official datasheet values
| Property | Typical value | Unit | Test method / condition |
|---|---|---|---|
| Tg by DSC | 200 | °C | IPC-TM-650 2.4.25C |
| Td at 5% weight loss | 360 | °C | TGA, IPC-TM-650 2.4.24.6 |
| T260 / T288 | >60 / >60 | minutes | TMA, copper removed; IPC-TM-650 2.4.24.1 |
| Z-axis CTE, pre-Tg | 50-70 | ppm/°C | IPC-TM-650 2.4.24C |
| Z-axis CTE, post-Tg | 250-350 | ppm/°C | IPC-TM-650 2.4.24C |
| X/Y-axis CTE, pre-Tg | 12 | ppm/°C | IPC-TM-650 2.4.24C |
| Thermal conductivity | 0.45 | W/m·K | ASTM E1952 |
| Thermal stress | Pass | visual | 10 seconds at 288°C, etched and unetched; IPC-TM-650 2.4.13.1 |
| Moisture absorption | 0.1 | % | IPC-TM-650 2.6.2.1A |
| Flammability | V-0 | rating | UL 94 |
| Relative Thermal Index | 130 | °C | UL 796 |
Dk and Df for impedance and loss modeling
The main datasheet lists Dk 3.00 and Df 0.0017 at 2GHz and 10GHz. Both use the Bereskin stripline method according to the table. Isola also publishes construction-specific core and prepreg Dk/Df tables; for example, the 2024 Revision D prepreg table shows values varying with glass style, resin content and dielectric thickness.
| Electrical item | 2GHz | 10GHz | How to use it |
|---|---|---|---|
| Dk | 3.00 | 3.00 | Starting comparison value; confirm the selected core/prepreg construction for simulation. |
| Df | 0.0017 | 0.0017 | Material-loss input, not a complete insertion-loss prediction. |
| Method | Bereskin stripline | Bereskin stripline | Do not compare directly with a value produced by another method without qualification. |
| Additional variables | Copper profile, resin content, thickness, frequency and temperature | Record these assumptions in the stackup and RF simulation package. | |
At millimeter-wave frequencies, copper roughness, etched sidewalls, solder-mask placement, launch geometry and antenna dimensions can dominate the difference between simulation and measurement. A low Df does not compensate for an uncontrolled fabrication drawing.
Standard laminate, prepreg and copper options
| Order item | Isola datasheet offering | What QFPCB must confirm |
|---|---|---|
| Laminate thickness | 2.5, 5, 7.5, 10, 12.5, 15, 20, 30 and 60 mil | Exact construction, tolerance, current availability and usable panel plan |
| Copper foil | VLP-2, 2-micron profile, 1oz and below | Foil profile and weight assumed in RF loss modeling |
| Copper weight | ⅓, ½ and 1oz standard; heavier or thinner may be available | Starting and finished copper by layer |
| Prepreg | Roll or panel form; tooling of prepreg panels | Glass style, resin content, pressed thickness, flow and bonding plan |
Why copper and geometry matter at 77GHz
As frequency rises, current concentrates closer to the conductor surface. Copper profile and etched geometry therefore affect conductor loss and phase. The artwork should identify critical antenna patches, coupled lines, filter gaps and launch dimensions; the stackup should identify the copper type used in the model.
For an Astra MT77 high-frequency PCB, QFPCB reviews etch compensation, finished copper, dielectric thickness and panel orientation before production. We do not publish an unconditional fine-line or impedance tolerance for every MT77 construction.
Hybrid and mechanically blind-via stackups
A hybrid stackup can place Astra MT77 on RF-critical layers while using a compatible FR-4 material for digital, power or mechanical layers. This may reduce material cost, but it introduces CTE, resin-flow, bonding and registration interfaces. The bonding material and full press cycle must be agreed before layout release.
QFPCB can also review a mechanically drilled blind-via stackup when the layer pairs, drill depth, remaining dielectric, copper plating and lamination sequence are manufacturable. We do not offer HDI or Any-Layer HDI stackup design for high-frequency laminate projects. Although Isola’s material datasheet describes MT77 as compatible with those technologies, that statement is a material attribute—not QFPCB’s high-frequency manufacturing capability.
QFPCB impedance simulation and technical support
QFPCB provides impedance-control PCB simulation, calculation and engineering review for Astra MT77 high-frequency hybrid stackups and mechanically drilled blind-via stackups. We check construction-specific Dk, pressed dielectric thickness, copper profile, trace geometry, reference planes, mask treatment and fabrication constraints before confirming the proposed PCB layer stackup.
PCB engineer Alan has more than 10 years of PCB CAM engineering experience. For technical review, contact [email protected]. The final material, stackup and verification plan remain project-specific.
When should you choose Astra MT77?
Choose MT77 when RF or mmWave loss, phase stability and antenna behavior justify an ultra-low-loss thermoset system. It is a practical candidate for automotive radar, RF front ends, long antenna feeds and aerospace or defense microwave circuits. Consider a less expensive material when the channel is short and loss margin is generous.
Compare MT77 with PTFE or another thermoset laminate using equivalent Dk/Df methods, frequency, copper profile, thickness availability and fabrication requirements. “Lower Df” alone is not a complete material-selection rule.
Files needed for an Astra MT77 quotation
- Gerber or ODB++ data and NC drill files
- Layer order, finished thickness and copper by layer
- Exact MT77 core and prepreg constructions
- Controlled-impedance and RF geometry table
- Copper foil type and profile assumed in simulation
- Hybrid material and bonding-material callouts
- Mechanical blind-via layer pairs and drill-depth requirements
- Surface finish, solder-mask openings and RF coupon requirements
- Prototype and production quantities
For high-speed digital channels, compare Astra MT77 with Panasonic MEGTRON 6 R-5775 using matched frequency, test method, copper profile and glass/resin construction. A lower headline Df does not by itself predict finished-channel insertion loss.
For another ultra-low-loss option, compare Astra MT77 with Panasonic MEGTRON 7 R-5785 using matched-frequency Dk/Df data, copper profile, glass construction, supply and qualification requirements.
Frequently asked questions
What are the Dk and Df of Astra MT77?
Isola lists typical Dk 3.00 and Df 0.0017 at both 2GHz and 10GHz using the Bereskin stripline method. These are useful comparison values, but the selected core or prepreg construction, resin content, dielectric thickness and copper profile should be confirmed before impedance or insertion-loss modeling.
Is Astra MT77 suitable for 77GHz radar?
Yes. Isola positions MT77 for millimeter-wave frequencies and automotive radar applications, including adaptive cruise control and blind-spot detection. Actual 77GHz performance depends on antenna geometry, copper roughness, etch accuracy, launches, dielectric thickness and verification. Material selection alone does not guarantee radar range or phase accuracy.
Is Astra MT77 a PTFE material?
No. Isola presents MT77 as a very-low-loss thermoset alternative to PTFE microwave laminates. Its datasheet describes FR-4 process compatibility and states that plasma desmear is not required. The fabricator must still qualify drilling, hole preparation, plating, lamination and RF geometry for the actual board.
Can QFPCB make an Astra MT77 HDI PCB?
No. QFPCB does not offer HDI or Any-Layer HDI stackup design for high-frequency laminate projects. We can support Astra MT77 high-frequency hybrid stackups or mechanically drilled blind-via stackups, subject to engineering review. The material manufacturer’s compatibility statement must not be interpreted as QFPCB production capability.
Can Astra MT77 be mixed with FR-4?
Yes, a reviewed hybrid construction may use MT77 on RF-critical layers and compatible FR-4 elsewhere. The stackup must address bonding material, lamination window, CTE mismatch, pressed thickness, copper balance and registration. QFPCB confirms the exact combination and material availability before quotation.
Does Tg 200°C define the operating temperature?
No. Tg is the glass-transition temperature measured by DSC. It is not the finished PCB’s continuous operating-temperature rating. The datasheet separately lists Td 360°C and RTI 130°C. Product temperature limits require an assembly-level assessment of materials, copper, solder joints, components and environment.
What copper should be used with Astra MT77?
The datasheet lists VLP-2 copper with a 2-micron profile for 1oz and below, plus standard ⅓, ½ and 1oz weights. Select copper from the RF loss and fabrication requirements, then keep the same profile assumption in simulation, stackup documentation and purchasing control.
What must be specified in an MT77 material callout?
State Astra MT77, the exact core or prepreg construction, dielectric thickness, copper type and weight, finished stackup, impedance or RF geometry, bonding material and substitution policy. For mechanical blind vias, include the layer pairs, drill depth and finished-hole requirements. A family name alone is insufficient.
Review the RF stackup before layout release
Astra MT77 combines ultra-low loss with thermoset processing advantages, but a successful RF board still depends on construction-specific data and controlled geometry. Send QFPCB your frequency range, stackup, copper assumptions, impedance targets, antenna features and blind-via requirements so we can review the manufacturable path before quotation.
Official references: Isola Astra MT77 datasheet, Revision C and Astra MT77 construction Dk/Df tables, Revision D.
