In high-performance electronic systems, PCB base material selection plays a decisive role in long-term reliability, signal integrity, and manufacturing yield. Among the widely used materials in the global PCB industry, Isola 370HR stands out as one of the most trusted high-thermal, high-reliability FR-4 laminates.
Whether you’re designing complex multilayer boards for networking systems, industrial controls, automotive electronics, or aerospace applications, 370HR has become the industry-standard benchmark thanks to its proven thermal stability, CAF resistance, and processing window.
In this article, we dive deep into what makes Isola 370HR special, its key properties, typical applications, and why many engineering teams continue to rely on this material for mission-critical designs.
What is Isola 370HR?
Isola 370HR is a multifunctional epoxy laminate & prepreg system engineered for advanced multilayer PCB structures. It is built on a patented high-performance resin system reinforced with high-quality E-glass fiber, delivering excellent thermomechanical stability and insulation reliability.
It belongs to the standard-loss FR-4 high-Tg class — ideal for applications requiring exceptional heat resistance and low failure risk under repeated thermal stresses.
Key Highlights at a Glance
| Feature | Data |
|---|---|
| Tg (DSC) | 180°C |
| Td (5% wt. loss) | 340°C |
| Loss Tangent (Df @ 2 GHz) | 0.0210 |
| Dielectric Constant (Dk @ 2 GHz) | 4.04 |
| Z-Axis CTE (50–260°C) | 2.8% |
| CAF Resistance | Excellent |
| Lead-Free / Reflow Cycles | Yes |
| UL Rating | V-0 |
Why 370HR Is Trusted Worldwide
Thermal Reliability You Can Count On
Modern electronics undergo frequent heating cycles — during assembly (lead-free reflow), rework, and long-term operation. 370HR delivers superior thermal endurance with:
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High Tg 180°C
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High Td 340°C
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Excellent delamination resistance under thermal shock
This ensures dimensional stability and mechanical strength in multilayer boards, especially HDI stack-ups and sequential lamination designs.
CAF-Resistant for Harsh Environments
Conductive Anodic Filament (CAF) failure is a major threat in fine-pitch PCB designs, especially in high-humidity applications.
370HR is engineered with high-quality E-glass and a resin system optimized to combat CAF formation — enabling long-term insulation reliability in demanding fields such as telecom base stations, EV electronics, aerospace, and military systems.
Excellent Processing & Manufacturing Window
PCB fabricators prefer 370HR due to its stable and familiar FR-4 process compatibility, making it efficient in production:
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Easy lamination control
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AOI-friendly (UV blocking & fluorescence)
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Good resin flow and fill characteristics
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Capable of multiple reflow cycles
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Compatible with fine-line HDI structures
This reduces risk and cost while improving yield rates.
Material Availability & Options
Laminate
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Thickness: 2 – 125 mil
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Copper foil: HTE Grade 3 / RTF
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Copper weights: 0.5 oz – 2 oz (optional thinner/thicker foils available)
Prepreg
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Available in roll or panel format
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Square-weave and mechanically-spread glass options
Where Is 370HR Used?
Isola 370HR supports a broad range of high-reliability markets:
Telecommunication & Networking
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Servers
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Routers & switches
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Base-station equipment
Industrial & Automation
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PLC controllers
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Factory automation electronics
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Instrumentation
Automotive Electronics
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Engine & control modules
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Power distribution units
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ADAS control boards
Aerospace & Defense
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Avionics systems
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Military communication devices
High-End Consumer & Medical
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Smart home control modules
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Medical imaging equipment
In short — anywhere long-term reliability + thermal durability matters, 370HR is a safe, proven choice.
Typical Electrical & Mechanical Properties
| Property | Typical Value |
|---|---|
| Tg (DSC) | 180°C |
| Td @ 5% weight loss | 340°C |
| CTE Z-axis (50-260°C) | 2.8% |
| Dk @ 2 GHz | 4.04 |
| Df @ 2 GHz | 0.0210 |
| Peel strength | 1.14 – 1.25 N/mm |
| Moisture absorption | 0.15% |
| Flame rating | UL 94 V-0 |
Conclusion
Isola 370HR remains one of the most reliable high-performance FR-4 solutions for demanding multilayer PCB applications. Its combination of:
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High thermal endurance
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Excellent CAF resistance
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Stable dielectric performance
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Broad manufacturing compatibility
makes it a top choice for engineers and PCB fabricators seeking performance without the cost of high-speed specialty materials.
If your design requires high reliability, multilayer complexity, and lead-free durability, 370HR is a material you can trust.
Interested in Using 370HR in Your Next PCB Project?
Our factory provides:
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Isola material sourcing (370HR, I-Tera, Tachyon series)
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High-layer-count & HDI PCB manufacturing
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Controlled-impedance stack-up design support
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Prototype + mass production
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Reliability & testing documentation
Contact us: sales@kkpcb.com
Learn more: www.kkpcba.com
