High-Performance 4-Layer MT770 RF PCB with Ultra-Low Loss MT77 Material
1. Introduction to MT77 Laminate and Resin Filled Vias
What is MT77 Laminate?
MT77 is an ultra-low loss, high-frequency laminate and prepreg material from Isola's Astra® series, designed specifically for RF, microwave, and millimeter-wave applications. With a stable dielectric constant (Dk) of 3.00 and an extremely low dissipation factor (Df) of 0.0017 at both 2 GHz and 10 GHz, it minimizes signal loss and ensures excellent signal integrity in high-frequency circuits. The material also offers high thermal reliability, with a glass transition temperature (Tg) of 200°C and decomposition temperature (Td) of 360°C, making it suitable for demanding environments.
What are Resin Filled Vias?
Resin filled vias are a specialized PCB manufacturing process where via holes are completely filled with epoxy resin and then planarized. This technique prevents solder wicking during SMT assembly, improves thermal and mechanical reliability, allows for via-in-pad design to increase routing density, and enhances electrical performance by reducing impedance discontinuities in high-speed signal paths.
2.PCB Details
| Item | Specification |
|---|---|
| Product Model | 4-Layer MT770 PCB |
| Layer Count | 4 |
| Core Material | Isola Astra® MT77 |
| Dielectric Structure | 5mil MT77 Core + MT77 1078 Prepreg + 5mil MT77 Core |
| Inner Layer Copper | 0.5 oz (~0.018mm) |
| Outer Layer Copper | 1 oz (~0.035mm) |
| Finished Thickness | 0.6mm (nominal) |
| Via Process | 0.25mm vias, resin filled and capped |
| Surface Finish | Immersion Silver |
| Solder Mask | Green |
| Silkscreen | White |
| Panel Size | 126mm x 78mm = 1 PC (including rail) |
3.PCB Stackup (4-Layer Rigid Structure)
The board features a symmetrical 4-layer stack-up with a total pressed thickness of approximately 0.574mm, optimized for signal integrity and mechanical stability.
Top Layer (L1) – 0.035mm copper foil for critical signal routing and component pads.
First Dielectric – 0.127mm MT77 Astra core between L1 and L2.
Inner Layer 1 (L2) – 0.018mm copper, typically used as ground or power plane.
Second Dielectric – Two layers of 0.107mm 1078 MT77 prepreg, total 0.214mm, between L2 and L3.
Inner Layer 2 (L3) – 0.018mm copper, symmetrical to L2.
Third Dielectric – 0.127mm MT77 Astra core between L3 and L4.
Bottom Layer (L4) – 0.035mm copper foil, symmetrical to L1.
This “signal-plane-plane-signal” configuration provides adjacent reference planes for controlled impedance and reduced EMI.
4.Typical Applications
RF & Microwave Communications: 5G/6G base station components, satellite communications, radar systems.
High-Speed Digital & Computing: Server backplanes, high-speed switches, test and measurement equipment.
Automotive Electronics: Millimeter-wave radar, V2X communication modules.
Aerospace & Defense: Avionics, electronic warfare systems, and navigation devices requiring high reliability and performance.
5.Quality Assurance
Artwork Format: Gerber RS-274-X
Quality Standard: IPC-Class-2
Availability: Worldwide
6.Conclusion
The 4-Layer MT770 PCB combines advanced MT77 material technology with reliable resin-filled via processes to deliver superior performance for high-frequency and high-speed applications. Its balanced stack-up and robust construction make it a dependable solution for next-generation communication, automotive, and aerospace systems.
