Overview
High Tg FR4 is an advanced version of standard FR4 epoxy glass laminate designed to withstand higher operating temperatures and more demanding thermal cycling environments. The term Tg (Glass Transition Temperature) refers to the temperature at which the epoxy resin transitions from a rigid glass-like state to a softer, rubber-like state.
Compared with standard FR4 (typically Tg 130–140°C), High Tg FR4 offers significantly improved thermal stability, dimensional stability, moisture resistance, reliability, and soldering performance, making it ideal for modern electronics and high-density PCB applications.
High Tg FR4 is widely used in:
- Multilayer PCBs
- Automotive Electronics
- Aerospace Electronics
- Industrial Control Systems
- Telecommunications Equipment
- Power Electronics
- LED Lighting Systems
- High-Reliability Electronics
Due to its superior thermal performance and long-term reliability, High Tg FR4 has become the preferred PCB substrate for advanced electronic products.
Material Specification
| Property | Value |
|---|---|
| Material Designation | High Tg FR4 |
| Full Name | High Glass Transition Temperature Flame Retardant Glass Epoxy Laminate |
| Material Family | Thermoset Composite |
| Reinforcement | Woven Glass Fiber |
| Matrix Material | High-Tg Epoxy Resin |
| Density | 1.80–2.00 g/cm³ |
| Appearance | Green, Yellow, Black, Natural |
| Typical Manufacturing Methods | Lamination, PCB Fabrication, CNC Machining |
| Standard Forms | PCB Laminates, Sheets, Panels |
Chemical Composition
High Tg FR4 utilizes enhanced epoxy resin systems combined with fiberglass reinforcement.
| Component | Function |
|---|---|
| Woven Glass Fiber | Structural Reinforcement |
| High-Tg Epoxy Resin | Thermal Stability |
| Flame Retardant Additives | Fire Resistance |
| Coupling Agents | Fiber Bonding |
| Specialty Fillers | Thermal Performance Enhancement |
The advanced resin system significantly improves heat resistance compared with standard FR4.
Common High Tg FR4 Grades
| Grade | Typical Tg |
|---|---|
| Standard High Tg FR4 | 150°C |
| Mid High Tg FR4 | 170°C |
| Premium High Tg FR4 | 180°C |
| Lead-Free Compatible FR4 | 170–180°C |
| Automotive Grade FR4 | 170–180°C |
| Halogen-Free High Tg FR4 | 170–180°C |
Mechanical Properties
Typical Values
| Property | Value |
|---|---|
| Tensile Strength | 320–520 MPa |
| Flexural Strength | 450–750 MPa |
| Compressive Strength | 450–650 MPa |
| Elastic Modulus | 20–26 GPa |
| Hardness | Rockwell M110–125 |
| Impact Resistance | Moderate |
Typical Mechanical Performance
| Property | Performance |
|---|---|
| Strength | Excellent |
| Rigidity | Outstanding |
| Thermal Dimensional Stability | Outstanding |
| Mechanical Reliability | Excellent |
High Tg FR4 maintains mechanical integrity under elevated temperatures.
Physical Properties
| Property | Value |
|---|---|
| Density | 1.80–2.00 g/cm³ |
| Water Absorption | <0.10% |
| Thermal Conductivity | 0.30–0.45 W/m·K |
| Moisture Resistance | Excellent |
| Dimensional Stability | Outstanding |
Improved moisture resistance enhances long-term electrical reliability.
Thermal Properties
| Property | Value |
|---|---|
| Glass Transition Temperature (Tg) | 150–180°C |
| Premium Grades | Up to 200°C |
| Continuous Service Temperature | 140–170°C |
| Decomposition Temperature (Td) | >320°C |
| Coefficient of Thermal Expansion (X-Y) | 10–16 ppm/°C |
| Z-Axis Expansion | Lower than Standard FR4 |
High Tg FR4 is specifically designed for lead-free soldering and thermal cycling applications.
Strength-to-Weight Ratio
| Material | Density (g/cm³) | Tensile Strength |
|---|---|---|
| High Tg FR4 | 1.90 | 450 MPa |
| Standard FR4 | 1.90 | 400 MPa |
| G10 | 1.85 | 450 MPa |
| Aluminum 6061 | 2.70 | 310 MPa |
High Tg FR4 offers excellent structural efficiency while maintaining electrical insulation.
Electrical Properties
Typical Values
| Property | Value |
|---|---|
| Volume Resistivity | >10¹⁴ Ω·cm |
| Surface Resistivity | >10¹³ Ω |
| Dielectric Strength | 18–25 kV/mm |
| Dielectric Constant (1 MHz) | 4.1–4.7 |
| Dissipation Factor | 0.008–0.020 |
Electrical Performance
| Property | Performance |
|---|---|
| Electrical Insulation | Outstanding |
| Signal Integrity | Excellent |
| High Voltage Performance | Excellent |
| Thermal Electrical Stability | Outstanding |
High Tg FR4 is suitable for high-reliability electronic systems.
Flame Resistance
| Property | Performance |
|---|---|
| UL94 Rating | V-0 |
| Self-Extinguishing | Yes |
| Flame Spread | Very Low |
| Fire Safety Performance | Outstanding |
Maintains the flame-retardant characteristics of standard FR4.
Moisture Resistance
| Property | Performance |
|---|---|
| Water Absorption | Very Low |
| Humidity Resistance | Excellent |
| CAF Resistance | Improved |
| Long-Term Reliability | Excellent |
Reduced moisture absorption improves PCB durability and reliability.
Thermal Cycling Performance
| Property | Performance |
|---|---|
| Lead-Free Solder Compatibility | Outstanding |
| Thermal Shock Resistance | Excellent |
| Layer Integrity | Excellent |
| Delamination Resistance | Outstanding |
High Tg FR4 is widely used for multilayer PCB manufacturing due to its thermal cycling performance.
Chemical Resistance
| Chemical Environment | Performance |
|---|---|
| Water | Excellent |
| Oils & Greases | Excellent |
| Solder Fluxes | Excellent |
| Cleaning Chemicals | Excellent |
| Dilute Acids | Good |
| Dilute Alkalis | Good |
Suitable for modern PCB assembly processes.
Machinability
| Process | Rating |
|---|---|
| CNC Milling | Excellent |
| CNC Drilling | Excellent |
| Routing | Outstanding |
| PCB Fabrication | Outstanding |
| Precision Machining | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| High Tg FR4 | Excellent |
| Standard FR4 | Excellent |
| G10 | Excellent |
| PEEK | Excellent |
Carbide tooling is recommended due to the fiberglass content.
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| PCB Manufacturing | Outstanding |
| Multilayer Lamination | Outstanding |
| CNC Machining | Excellent |
| SMT Assembly | Outstanding |
High Tg FR4 is optimized for modern electronics manufacturing.
International Equivalent Standards
| Standard | Equivalent Grade |
|---|---|
| NEMA | High Tg FR4 |
| IPC-4101 | High Tg Epoxy Laminate |
| UL | FR4 V-0 |
| IEC | Glass Epoxy Laminate |
| DIN | Hoch Tg Epoxy Laminate |
| GB/T (China) | 高TG环氧玻纤板 |
Available Forms
| Product Type | Availability |
|---|---|
| PCB Laminates | Yes |
| Copper-Clad Panels | Yes |
| Sheets | Yes |
| Multilayer PCB Materials | Yes |
| CNC Machined Components | Yes |
Typical Applications
PCB Industry
- Multilayer PCBs
- HDI Boards
- Lead-Free PCB Assemblies
- High-Density Electronics
Automotive Electronics
- ECU Systems
- Battery Management Systems
- ADAS Electronics
- Power Control Modules
Aerospace Industry
- Avionics Systems
- Navigation Electronics
- Mission-Critical Circuit Boards
Telecommunications
- Network Infrastructure
- 5G Equipment
- High-Speed Communication Boards
Industrial Automation
- PLC Systems
- Power Electronics
- Industrial Controllers
LED Industry
- High-Power LED Drivers
- Thermal Management Boards
- Lighting Control Systems
Advantages
Higher Thermal Stability
Superior resistance to elevated temperatures compared with standard FR4.
Improved Reliability
Enhanced performance under thermal cycling conditions.
Lead-Free Compatible
Designed for modern RoHS-compliant soldering processes.
Better Dimensional Stability
Reduced warpage and expansion during assembly.
Enhanced Moisture Resistance
Improves long-term PCB reliability.
Excellent Electrical Properties
Maintains outstanding insulation and dielectric performance.
Limitations
Higher Cost
More expensive than standard FR4 materials.
Limited High-Frequency Performance
Not as suitable as specialized RF laminates such as Rogers materials.
Brittle Structure
Like all fiberglass laminates, it is less impact-resistant than engineering plastics.
Tool Wear During Machining
Glass fibers accelerate cutting tool wear.
Comparison with PCB Materials
| Property | High Tg FR4 | Standard FR4 | Rogers 4350B | G10 |
|---|---|---|---|---|
| Tg | Outstanding | Good | Excellent | Moderate |
| Thermal Cycling | Outstanding | Good | Excellent | Moderate |
| Cost | Moderate | Low | High | Low |
| Electrical Performance | Excellent | Excellent | Outstanding | Excellent |
| PCB Applications | Outstanding | Excellent | RF Applications | Limited |
Comparison with Standard FR4
| Property | High Tg FR4 | Standard FR4 |
|---|---|---|
| Glass Transition Temperature | Higher | |
| Lead-Free Compatibility | Better | |
| Thermal Cycling Resistance | Better | |
| Reliability | Better | |
| Cost | Higher |
High Tg FR4 is preferred for advanced electronics requiring higher reliability and thermal stability.
Available Surface Finishes
Standard Finishes
- Copper Clad Surface
- Laminate Surface
- Matte Finish
Functional Finishes
- High Reliability PCB Finish
- Lead-Free Compatible Finish
- High Thermal Stability Finish
Specialty Grades
- Tg150 FR4
- Tg170 FR4
- Tg180 FR4
- Automotive Grade FR4
- Halogen-Free High Tg FR4
Frequently Asked Questions (FAQ)
What is High Tg FR4?
High Tg FR4 is an advanced flame-retardant glass epoxy laminate with a glass transition temperature typically between 150°C and 180°C.
What is High Tg FR4 used for?
Typical applications include:
- Multilayer PCBs
- Automotive Electronics
- Aerospace Electronics
- Industrial Control Systems
Why is High Tg FR4 better than Standard FR4?
High Tg FR4 offers improved thermal stability, moisture resistance, reliability, and lead-free solder compatibility.
Is High Tg FR4 suitable for lead-free assembly?
Yes. High Tg FR4 is specifically designed to withstand the higher temperatures used in lead-free soldering processes.
Is High Tg FR4 electrically insulating?
Yes. It provides excellent dielectric and insulation properties.
Why choose High Tg FR4?
Because it combines:
- Superior Thermal Stability
- Improved Reliability
- Excellent Electrical Insulation
- Better Moisture Resistance
- Lead-Free Compatibility
What is the difference between High Tg FR4 and Rogers material?
High Tg FR4 is optimized for thermal reliability and general PCB applications, while Rogers materials are designed for high-frequency RF and microwave circuits.
Does GCNOV provide High Tg FR4 manufacturing services?
Yes. GCNOV provides:
- High Tg FR4 CNC Machining
- PCB Material Fabrication
- Electrical Insulation Components
- Precision FR4 Parts
- Prototype Development
- Low-Volume Production
- Mass Production