FR4 Fiberglass Board: Core Insulation Material for New Energy Vehicles and Photovoltaic Inverters

I. Fundamental Understanding of FR4 Board

FR4, short for Flame Retardant Type 4, is a composite material reinforced with electronic-grade glass fiber cloth and epoxy resin as the matrix. It is the most widely used base material in PCB (Printed Circuit Board) manufacturing and electrical insulation applications. FR4 is not a single material grade but a general term for a category of insulation boards compliant with NEMA standards. Its core characteristics determine its irreplaceability in the new energy sector.

1.1 Core Performance Specifications of FR4

1.2 Classification and Selection of FR4 Board

• Standard FR4 (Tg 130°C): Suitable for consumer electronics conventional PCBs, general thermal stress, optimal cost-performance ratio
• Medium Tg FR4 (Tg 150°C): Recommended for automotive electronics, especially new energy vehicle "three-electric" systems
• High Tg FR4 (Tg 170°C and above): Suitable for power modules, IGBT backing plates, and scenarios with stringent reliability requirements

II. FR4 Applications in New Energy Vehicles

2.1 On-Board OBC (On-Board Charger) Insulation Support

New energy vehicle OBCs operate in a temperature range of -40°C to +85°C (with some conditions reaching 105°C). The heat dissipation baseplate of internal power devices (MOSFETs, IGBTs) requires high-reliability insulation material support. High-Tg FR4 mid-grade board plays the following roles here:

• Insulation isolation: Electrical isolation between the high-voltage side (400V/800V) and the low-voltage side (12V), meeting ISO 6469 electrical safety requirements
• Mechanical support: Supports power modules, provides a flat mounting surface, and withstands vibration loads (compliant with ISO 16750 vibration testing)
• Auxiliary thermal management: Works with thermal grease to conduct heat to the metal enclosure, achieving thermal balance

2.2 BMS (Battery Management System) PCB Substrate

As the "brain" of the power battery, the BMS requires extremely high data acquisition accuracy. The low Dk/Df characteristics of FR4 ensure signal integrity of analog signal traces (especially for 0.1mV-level voltage sampling accuracy), while its excellent insulation performance provides reliable electrical isolation for CAN bus communication at high-voltage platforms (400V/800V). BMS main boards recommend high-Tg FR4 (≥150°C) to cope with temperature rise from high-current charging and discharging.

2.3 Vehicle-Mounted DCDC Converter

DCDC modules need to handle high-current switching (peak currents can exceed 200A) in a compact space. The temperature resistance and flame retardancy of PCB substrate directly affect thermal runaway safety. High-Tg FR4 (≥150°C) is recommended to provide sufficient temperature margin. Additionally, copper thickness in power trace areas is typically 2oz~4oz, placing higher requirements on board peel strength.

2.4 Other FR4 Applications in New Energy Vehicles

• DC EV Charging Stations (DC EV Charger): PCB substrate for PFC modules and DCDC modules
• Motor Controller (MCU): Insulation support for IGBT/MOSFET driver circuits
• Vehicle VCU Control Board: PCB substrate for signal processing and control logic

III. FR4 Applications in Photovoltaic Inverters

Photovoltaic inverter operating environments are even more demanding: outdoor installation, large day-night temperature differences (-30°C to +70°C), UV radiation, and high-altitude low-pressure conditions. FR4 board applications in inverters primarily include:

• Power module backing plate: Serves as the mounting baseplate for IGBT/MOSFET modules, providing electrical insulation and mechanical fixation
• Control PCB substrate: PCB board for driver circuits, sampling circuits, and communication interfaces (PLC/Modbus)
• Insulation partition board: Insulation isolation between busbars to prevent phase-to-phase short circuits
• MPPT Controller Board: PCB substrate for maximum power point tracking circuits, requiring higher dielectric performance from the board material

Key Selection Recommendations: FR4 for photovoltaic inverters should have Tg ≥170°C, and suppliers should provide a Tropical damp heat test report (85°C / 85% RH / 1000h) to verify long-term reliability under high-temperature, high-humidity environments. For outdoor inverters, the board's UV resistance should also be considered (can be enhanced by applying conformal coating).

IV. Comparison: FR4 Board vs. G10/3240 Phenolic Fiberglass Board

V. Key Parameters for FR4 Board Selection

5.1 Thickness Tolerance

For power module backing plate applications, thickness tolerance is typically required at ±0.1mm to ensure flatness compatibility with thermal grease.

5.2 Copper Foil Peel Strength

For applications requiring PCB traces, peel strength must be ≥1.0N/mm (standard conditions) and ≥0.8N/mm (after thermal shock).

5.3 Dielectric Withstand Voltage

The perpendicular laminate dielectric withstand voltage of FR4 board should be ≥20kV/mm (AC, 1-minute test), which is a hard requirement for high-voltage system (>400V) selection.

VI. FR4 Board Services from Dongguan Chaorong Electronics Co., Ltd.

Dongguan Chaorong Electronics Co., Ltd. supplies multi-specification FR4 fiberglass boards with standard stock covering:

• Thickness range: 0.3mm ~ 3.2mm, custom cutting available, low minimum order quantity
• Standard sizes: 1020×1020mm, 1020×1220mm, 1220×2440mm
• Tg grades: Standard Tg130 / Medium Tg150 / High Tg170 all in stock, custom high-Tg specifications supported
• Special specifications: Precision cutting, routing, and counterbore machining available according to customer drawings
• Certification support: Certificate of Analysis (COA), RoHS reports provided; UL yellow card available upon customer request

Leveraging the advantages of the Dongguan manufacturing cluster, the company provides one-stop services including rapid prototyping, mass production supply, and technical support for new energy industry chain customers, with standard products delivered in 3~5 days.