Isola 370HR PCB Laminate

Isola 370HR is a high-performance FR-4 laminate system designed for applications that demand elevated thermal reliability, resistance to conductive anodic filament (CAF) formation, and compatibility with lead-free assembly processes. It occupies the performance tier between standard FR-4 and specialty low-loss laminates like Megtron or Rogers — delivering meaningfully better reliability than commodity FR-4 at a fraction of the cost of RF-grade materials.

Key material properties

Isola 370HR provides a glass transition temperature (Tg) of 180°C by DSC, a decomposition temperature (Td) of 340°C, and a z-axis CTE of 2.7% from 50 to 260°C. These thermal properties make it well suited for multilayer constructions that will undergo multiple lead-free reflow cycles at 260°C peak temperature without delamination or barrel cracking. The dielectric constant (Dk) is approximately 4.04 at 1 GHz, and the dissipation factor (Df) is 0.021 at 1 GHz — adequate for digital signal integrity in designs operating up to several gigahertz but not intended for low-loss RF applications.

CAF resistance is a standout feature of Isola 370HR. CAF is an electrochemical failure mechanism where copper ions migrate along glass fiber interfaces under voltage bias and humidity, eventually creating a conductive filament that shorts adjacent conductors. 370HR uses a proprietary resin system with enhanced glass-resin adhesion that resists CAF formation under accelerated testing conditions — making it a standard choice for automotive, industrial and aerospace boards that must survive decades of field service.

When to specify Isola 370HR

Isola 370HR fits applications where standard FR-4 Tg 135-150°C is insufficient but where the cost and lead time of specialty laminates are not justified. Automotive electronics (ADAS modules, body control units, powertrain controllers) frequently specify 370HR because IATF 16949 quality requirements demand a laminate with proven CAF resistance and thermal cycling endurance. Industrial control boards that operate in high-ambient-temperature environments benefit from the elevated Td and low z-axis expansion. Server and networking boards that undergo multiple rework cycles during assembly prefer 370HR for its margin of thermal safety above the lead-free reflow peak.

For designs requiring lower dielectric loss — such as 10 Gbps+ SerDes channels or RF front-end sections — consider Megtron 6 or Rogers 4350B instead. Isola 370HR is optimized for thermal and mechanical reliability rather than electrical signal performance at high frequencies.

Stackup and construction guidance

AstroPCB stocks Isola 370HR in standard core thicknesses and prepreg styles for multilayer constructions from 4 to 20+ layers. The laminate is compatible with standard FR-4 processing: no special drill parameters, plating chemistry modifications or lamination cycle changes are required compared to production-grade FR-4 processing. This compatibility means that switching from a commodity FR-4 to Isola 370HR typically does not increase fabrication lead time or require re-qualification of the manufacturing process.

For hybrid stackups that combine 370HR with other laminates (for example, a high-speed design that uses Megtron cores for signal layers and 370HR for power and ground planes), consult the engineering team during stackup planning. The Tg and CTE compatibility between materials must be evaluated to ensure reliable lamination and thermal cycling performance.

Comparison with other high-Tg laminates

The high-Tg laminate category includes several alternatives to Isola 370HR: Isola FR408HR (lower Df for higher-speed digital), Shengyi S1000-2M (lower cost alternative popular in Asian fabrication), Panasonic Megtron 4 (bridge between FR-4 and low-loss), and Nelco N4000-13 EP SI. Each has trade-offs in Dk/Df, CAF resistance, cost and regional availability. AstroPCB’s engineering team can recommend the optimal laminate based on your specific electrical, thermal and reliability requirements.

Request a quote with Isola 370HR

Upload your design files and specify Isola 370HR as the laminate requirement. The engineering team will confirm material availability, build the stackup with appropriate core and prepreg combinations, and return a quotation with pricing and lead time.

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