ISOLA 370HR High-Tg FR-4 PCB – 6-Layer, 1.6mm, ENIG, 50Ω Impedance, IPC Class 3 for Aerospace & Automotive

Quick Answer

What is ISOLA 370HR?

It's a high-performance, 180°C Tg multifunctional epoxy FR-4 system reinforced with E-glass fabric, designed for multilayer PCB applications demanding maximum thermal reliability. With a decomposition temperature (Td) of 340°C, T260 > 60 minutes, and T288 > 30 minutes, 370HR delivers exceptional thermal stability while maintaining standard FR-4 processability — making it a top choice for sequential lamination designs, aerospace, automotive, and industrial electronics.

What PCB can you build with it?

We offer a complete 6-layer multilayer PCB solution based on ISOLA 370HR, featuring 1.6mm finished thickness, 1 oz copper, ENIG finish, green solder mask with white silkscreen, 50Ω impedance-controlled traces, and IPC Class 3 reliability — ideal for high-reliability applications where thermal performance and signal integrity are critical.

1. Material Overview

The ISOLA 370HR is a high-performance 180°C glass transition temperature (Tg) FR-4 epoxy system engineered for multilayer printed wiring board (PWB) applications requiring maximum thermal performance and long-term reliability. Manufactured with a unique multifunctional epoxy resin and reinforced with electrical-grade (E-glass) glass fabric, 370HR delivers:

Superior thermal performance vs. traditional FR-4

Low Z-axis expansion for enhanced plated through-hole (PTH) reliability

Mechanical, chemical, and moisture resistance that equal or exceed standard FR-4

Full FR-4 processability – no special processing equipment required

Laser fluorescing and UV blocking for seamless compatibility with AOI systems, optical positioning systems, and photoimageable solder mask imaging

The 370HR system is recognized as best-in-class for sequential lamination designs, making it the material of choice for complex, high-layer-count boards with blind/buried vias.

2. ISOLA 370HR Technical Data Sheet

3. Application Fields

ISOLA 370HR is trusted across high-reliability industries where thermal performance and long-term durability are paramount:

Networking and Communications: High-speed routers, switches, and base station equipment.

Aerospace and Defense: Radar, avionics, and satellite systems.

Medical Electronics: Imaging devices and diagnostic equipment.

Automotive Electronics: Advanced driver-assistance systems (ADAS) and infotainment systems.

4. Custom Multilayer PCB – Complete Specification

Based on ISOLA 370HR, we offer a complete 6-layer PCB solution with the following specifications:

Stack-Up Configuration

Board Specifications

Top-Layer Impedance Detail

FAQ

Q1: What makes ISOLA 370HR different from standard FR-4?

A: 370HR offers significantly higher thermal performance. Key differences include:

Tg 180°C vs. ~135°C for standard FR-4 — better lead-free soldering compatibility

Td 340°C — higher decomposition resistance

T260 > 60 min / T288 > 30 min — exceptional thermal stress resistance for sequential lamination

Lower Z-axis expansion (2.8%) — better PTH reliability

AOI/UV compatibility — supports automated optical inspection

Yet it maintains standard FR-4 processability, so no special equipment is required.

Q2: What is the significance of T260 and T288?

A: T260 and T288 measure how many minutes a material can withstand 260°C and 288°C respectively before delaminating or failing.

370HR T260 > 60 minutes — exceptional stability at lead-free soldering temperatures

370HR T288 > 30 minutes — outstanding resistance to rework/high-temperature excursions

These values are critical for sequential lamination, where the board undergoes multiple high-temperature press cycles.

Q3: Can ISOLA 370HR support sequential lamination with blind vias?

A: Yes. In fact, 370HR is recognized as best-in-class for sequential lamination designs. Its high thermal stability (Tg 180°C, Td 340°C, T288 > 30 min) ensures reliable interlayer bonding and PTH integrity across multiple lamination cycles. The 6-layer PCB example described above can incorporate blind vias using this material.

Q4: Is 370HR suitable for impedance-controlled designs?

A: Absolutely. With stable Dk values ranging from 4.24 @ 100 MHz to 3.92 @ 10 GHz, 370HR provides consistent dielectric performance across frequency. The 50Ω impedance-controlled top-layer traces on a 1.6mm board with 11 mil trace width demonstrate this capability. We can design and manufacture to your specific impedance requirements.

Q5: What surface finishes are compatible with 370HR?

A: 370HR is compatible with all standard PCB surface finishes, including:

• ENIG (Electroless Nickel/Immersion Gold) — used in the example above
• ENEPIG
• HASL (lead-free)
• OSP
• Immersion Silver
• Immersion Tin

Our example uses ENIG with 2 µ" gold thickness for excellent solderability and flatness.

Q6: Is ISOLA 370HR RoHS-compliant?

A: Yes. 370HR is RoHS-compliant and halogen-free compatible (check with Isola for specific halogen-free grades). It also meets UL94 V-0 flame-rating requirements.

Q7: What is the maximum operating temperature for 370HR?

A: The UL maximum operating temperature is rated at 130°C. However, the material can withstand higher peak temperatures during soldering and rework (up to 288°C for short durations), as demonstrated by its T288 > 30 minute rating.

Q8: Can you produce IPC Class 3 boards with 370HR?

A: Yes. Our 6-layer 370HR board example is specified to IPC Class 3 — the highest reliability class for aerospace, medical, defense, and automotive applications. This includes 25 µm minimum hole wall copper and rigorous inspection/testing standards.

Q9: What is the typical lead time for custom 370HR PCBs?

A: Lead times vary based on complexity and quantity. For 6-layer boards like the example described, typical lead times range from 10 to 18 working days. Please contact us for specific project timelines.

Ready to Get Started?

Whether you need ISOLA 370HR raw laminate/prepreg, a fully fabricated multilayer PCB with impedance control, or a complex sequential lamination design, we are here to help.

Contact us today for:

Material sampling and testing

Custom stack-up design assistance

Impedance calculation and design support

PCB quoting and DFM revie

Technical support for your specific application