FR-4 PCB Laminate
Dk 4.2-4.5 | Multiple Tg grades (130-180C) — the industry workhorse material for 80%+ of all PCB production worldwide.
4.2-4.5
Dk @ 1 GHz
130-180
Tg Range (C)
UL V-0
Flame Rating
80%+
Market Share
What is FR-4 Laminate?
FR-4 (Flame Retardant class 4) is the dominant PCB substrate material, accounting for over 80% of global PCB production. It consists of woven fiberglass cloth impregnated with epoxy resin, providing an excellent balance of electrical insulation, mechanical strength, and manufacturing cost that has made it the default choice for electronics since the 1960s.
Multiple Tg (glass transition temperature) grades address different reliability requirements: Tg 130-140C for consumer and cost-sensitive applications, Tg 150-170C for standard industrial and telecom equipment, and Tg 170-180C for automotive, military, and high-reliability designs requiring lead-free assembly compatibility.
AtlasPCB maintains inventory across all standard FR-4 grades from major manufacturers (Shengyi, ITEQ, Nanya, Kingboard) enabling immediate production start without material procurement delays. From single-sided boards to 40+ layer multilayer constructions, FR-4 remains the foundation of electronics manufacturing.
Lowest Cost
Highest-volume material with most competitive pricing at any quantity.
Universal Processability
Every PCB fabricator worldwide is optimized for FR-4 production.
Full Compliance
UL, IPC, RoHS, REACH — all certifications readily available.
Multiple Tg Grades
130-180C options match reliability requirements to budget.
FR-4 Laminate Key Properties
Representative values from the manufacturer datasheet.
| Property | Value | Why it matters |
|---|---|---|
| Dielectric constant (Dk) | 4.2-4.5 @ 1 GHz | Standard for digital circuits below 5 Gbps. |
| Dissipation factor (Df) | 0.017-0.025 @ 1 GHz | Adequate for frequencies below 3 GHz. |
| Glass transition (Tg) | 130-180 C | Multiple grades for different thermal requirements. |
| Decomposition temp (Td) | 300-340 C | Higher Tg grades offer better thermal stability. |
| CTE z-axis | 50-70 ppm/C (below Tg) | Manageable with proper via design. |
| Flammability | UL 94 V-0 | All grades meet flame retardant requirements. |
| Peel strength | 1.0+ N/mm | Excellent copper adhesion for all plating processes. |
| Moisture absorption | 0.10-0.15% | Moderate — bake before assembly if stored long-term. |
| Layer capability | 1 to 40+ layers | No practical limit to layer count with proper design. |
Choosing the Right FR-4 Tg Grade
Tg 130-140C (Standard): Suitable for consumer electronics, single-use devices, and applications with hand-solder or low-temperature reflow. Cost-optimized for high-volume production where thermal stress is minimal. Not recommended for lead-free reflow profiles exceeding 245C peak.
Tg 150-170C (Mid-Tg): The mainstream choice for industrial equipment, telecom, computing, and general-purpose designs requiring lead-free assembly. Adequate thermal reliability for 1000+ thermal cycles between -40C and +85C. Represents the best balance of cost and reliability for most applications.
Tg 170-180C (High-Tg): Required for automotive under-hood electronics, military/aerospace applications, and any design requiring Class 3 IPC reliability. Lower CTE z-axis expansion provides better via reliability through extended thermal cycling. Recommended for boards thicker than 2.0mm or layer counts exceeding 12.
Tg 130C — Budget
Consumer electronics and cost-sensitive applications.
Tg 150C — Standard
Industrial, telecom, and computing — the mainstream choice.
Tg 170C — High Reliability
Automotive, military, and Class 3 IPC requirements.
Tg 180C — Maximum
Extreme reliability and thickest multilayer constructions.
FR-4 Tg Grade Comparison
Selecting the right FR-4 grade for your reliability and cost requirements.
| Material | Dk | Df | Best For |
|---|---|---|---|
| FR-4 Standard (Tg 130-140) | 4.5 | 0.025 | Consumer, LED, IoT — lowest cost, basic reliability. |
| FR-4 Mid-Tg (Tg 150-170)This page | 4.3 | 0.020 | Industrial, telecom, computing — mainstream standard. |
| FR-4 High-Tg (Tg 170-180) | 4.2 | 0.018 | Automotive, military, thick boards — maximum reliability. |
| Low-Loss FR-4 (IT-180A class) | 3.9 | 0.010 | Enhanced FR-4 — bridge to low-loss without PTFE. |
| Rogers RO4350B | 3.48 | 0.004 | RF upgrade — when FR-4 loss is inadequate. |
FR-4 Laminate Applications
Consumer electronics, industrial controls, IoT devices, LED lighting, power supplies, prototyping
Consumer Electronics
Smartphones, laptops, tablets, and consumer IoT devices.
Industrial Controls
PLCs, motor drives, power supplies, and instrumentation.
LED Lighting
LED driver boards and low-power lighting controls.
Automotive Electronics
Body control, infotainment, and non-safety-critical automotive.
Telecom Equipment
Router, switch, and access point boards below 10G speeds.
Power Electronics
AC/DC converters, inverters, and battery management systems.
FR-4 Design Best Practices
Select Tg grade based on your maximum operating temperature and assembly process. For lead-free reflow (peak 260C), use Tg 150C minimum. For automotive or designs requiring IPC Class 3 reliability with 1000+ thermal cycles, specify Tg 170C or higher.
FR-4 Dk varies significantly with frequency (4.5 at 100 MHz to 4.0 at 10 GHz) and with resin content. For impedance-controlled designs, specify the target impedance and let the fabricator optimize trace geometry for their specific FR-4 material and stackup.
Get Instant QuoteMatch Tg to Process
Lead-free reflow needs Tg 150C+. Automotive needs Tg 170C+.
Impedance-Controlled
Specify target impedance — fabricator matches to their material.
Via Reliability
High-Tg for thick boards (over 2mm) and high layer counts (12+).
Cost Optimization
Do not over-specify Tg — use the minimum grade that meets requirements.
Genuine FR-4 Laminate, Verified on Every Order
Material CoC
Certificate of Conformance with lot number ships with every order.
Stock Verified
We confirm laminate availability before order confirmation.
No Substitutions
Specified material guaranteed — never swapped without written approval.
FAQ
FR-4 Laminate Questions
What is FR-4?
FR-4 (Flame Retardant class 4) is the industry standard PCB substrate — woven fiberglass with epoxy resin. It accounts for over 80% of global PCB production.
What Tg grade should I choose?
Tg 130C for budget consumer, Tg 150C for standard industrial/telecom (most common), Tg 170C+ for automotive/military or thick multilayer boards requiring lead-free assembly.
What frequency range suits FR-4?
FR-4 works well below 3 GHz and for digital signals below 5 Gbps. Above these, consider low-loss alternatives like IT-180A, Megtron, or Rogers.
Is FR-4 suitable for automotive?
Yes — High-Tg FR-4 (170-180C) is widely used in automotive electronics for body control, infotainment, and non-safety-critical systems. IATF 16949 qualified sources available.
What is AtlasPCB's minimum order for FR-4?
No minimum order. From 1 prototype board to 100,000+ production panels, all FR-4 grades available.
Need FR-4 PCB fabrication?
All FR-4 grades from standard to high-Tg — single-sided to 40+ layers, no minimum order quantity.
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