FR-4 PCBS
FR-4 PCBs: The Industry Standard for Printed Circuit Boards
FR-4 (Flame Retardant-4) is the most widely used material in Printed Circuit Boards (PCBs). It is a fiberglass-reinforced epoxy laminate known for its high mechanical strength, excellent electrical insulation, and reliable heat resistance. From your mouse and keyboard to your smartphone, TV, or Wi-Fi router—almost every electronic device depends on PCBs made with FR-4 material.
FR-4 has become the industry standard PCB material because it offers the perfect balance of performance, durability, and cost-effectiveness. For applications that do not generate extreme heat, FR-4 PCBs remain the most dependable solution.
Cost-Effective – More affordable than high-performance alternatives.
Versatile – Suitable for single-layer, double-layer, and multilayer PCBs.
Reliable – Provides strong electrical insulation and flame resistance (UL94-V0 rated).
Easy to Manufacture – Can be drilled, etched, and processed efficiently for mass production.
For more information on FR-4 PCB capabilities and how we can customize these boards for you, please see PCB Capabilities.
How FR-4 PCBs Are Made
FR-4 PCBs are fabricated using copper-clad laminates. A thin layer of copper foil is laminated to one or both sides of an FR-4 glass epoxy panel. The circuitry is then etched into the copper, and as more layers are added, the complexity of the PCB increases.
Key Features of Cofan's FR-4 PCB
Composition
- Made of woven fiberglass cloth with an epoxy resin binder.
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Flame-retardant epoxy ensures self-extinguishing properties when exposed to fire.
Electrical Properties
-
High dielectric strength for excellent insulation between conductive layers.
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Low moisture absorption, ensuring stability in humid environments.
Mechanical Strength
- Strong, durable, and lightweight.
-
Can withstand mechanical stress without breaking or bending easily.
Thermal Resistance
- Glass transition temperature (Tg): Typically 130°C to 180°C, depending on grade.
- Suitable for moderate heat applications.
Why is FR-4 Used in PCBs?
- Cost-Effective: Affordable compared to other high-performance materials.
- Versatile: Used in single-layer, double-layer, and multilayer PCBs.
- Reliable: Offers good electrical insulation and flame resistance (UL94-V0 rated).
- Easy to Fabricate: Can be drilled, etched, and processed easily for mass production.
FR-4 vs. Other PCB Materials
|
Feature
|
FR-4
|
Aluminum PCB
|
Ceramic PCB
|
Polyimide (Flex PCB)
|
|---|---|---|---|---|
|
Thermal Conductivity
|
Low
|
High
|
Very High
|
Low
|
|
Mechanical Strength
|
High
|
Medium
|
High
|
Flexible
|
|
Cost
|
Low
|
Medium
|
High
|
High
|
|
Flame Resistance
|
Yes
|
Yes
|
Yes
|
Yes
|
|
Applications
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General Electronics
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Power Electronics, LED
|
High-Frequency, RF
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Flexible Circuits
|
|
Process
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Item
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Normal SPEC
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Special SPEC
|
|---|---|---|---|
|
01/ Materials
|
150℃ to 180℃ Layer count
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16 L
|
20 L
|
|
02/ Mask
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Color
|
Green / blue / Red / Black / White / Golden / Clear
|
|
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03/ Silkscreen
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Color
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White / Black / Red / Yellow
|
|
|
04/ Testing
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1. Open / Short Testing Spacing
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Dedicate: 6ml Fly probe, Spacing: 4mil (Smd Pitch: 10 mil)
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Tolerance 5%
|
|
2. Open / Short Board Size ​
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Dedicate: 600x400mm(max) , Fly probe: 640x450mm(max) ​
|
|
|
|
3. Open / Short Testing Condition
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Dedicate: 250V / 50Ω / 2MΩ Fly probe: 250V / 50Ω / 10MΩ min / max: 1MΩ ~ 20MΩ ​ |
|
|
|
4. Netlist Test
|
1) Measure Machine: POLAR 2) Tolerance: ±10% 3) design: Single End / Differential ±10% 4) Testing Pitch: 0.254mm |
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|
|
05/ Finish Type
|
HASL Carbon Ink Imm gold Hard gold Imm Tin Leadfree HAL Imm Silver |
Imm Gold+HASL Imm Gold+ENTEK Carbon+ENTEK Imm gold+G / F(3~30μ) Partial Hard Gold Partial Imm Gold |
Imm Gold + SMOBC
|
|
Density
|
|||
|---|---|---|---|
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Title
|
Standard
|
Advanced & Development
|
|
|
Thickness Tolerance
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+/- 8
|
+/- 6
|
|
|
Thickness (Minimum / Maximum)
|
7 / 300
|
5 / 440
|
|
|
QFP
|
0.5 mm
|
0.4mm
|
|
|
Minimum Solder mask Web
|
0.005
|
0.004
|
|
|
Minimum Prepreg Fill
|
0.0025
|
0.002
|
|
|
Minimum Line/Spacing - Internal 1/2 oz
|
0.004
|
0.003 1/3 oz
|
|
|
Minimum Line/Spacing - External 1/2 oz
|
0.004
|
0.003 1/3 oz
|
|
|
Minimum Drilled Hole Size
|
0.008
|
0.006
|
|
|
Minimum Core Thickness
|
0.004
|
0.003
|
|
|
Layer to Layer Registration
|
+/- .005
|
+/- .003
|
|
|
Land Size (Diameter over Drill)
|
0.010
|
0.008
|
|
|
BGA
|
0.5 mm
|
0.4mm
|
|
|
Aspect Ratio - Line Card
|
12:01
|
14:01
|
|
|
HDI VIAS
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|||
|---|---|---|---|
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Title
|
Dimension
|
Advanced & Development
|
|
|
Microvia Aspect Ratio
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0.5:1
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|
|
|
Variable Depth Laser Via (Depth / Diameter)
|
0.004/ 0.006
|
0.004/ 0.005
|
|
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Minimum Laser Via (Drill / Capture Pad)
|
0.006/ 0.016
|
0.005/ 0.014
|
|
|
BBV Mechanical Drill
|
0.010
|
0.008
|
|
|
Impedance Control
|
|||
|---|---|---|---|
|
Title
|
Standard
|
Advanced & Development
|
|
|
28 - 260Ohms
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+/-10%
|
+/-7%
|
|
|
50 - 150 Ohms
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+/-10%
|
+/-7%
|
|
|
Copper Weights
|
|||
|---|---|---|---|
|
Title
|
Standard
|
Advanced & Development
|
|
|
Min Outer Base Copper - plated layers
|
1/2 oz
|
1/4 oz
|
|
|
Max Outer Base Copper - plated layers
|
5 oz
|
5 oz
|
|
|
Max Inner Copper Foil - non plated layers
|
4 oz
|
5 oz
|
|
|
Min Inner Copper Foil - non plated layers
|
1/4 oz
|
1/4 oz
|
|
Applications
FR-4 boards are widely used in consumer electronics, industrial equipment, telecommunications, automotive systems, and medical devices. Their adaptability makes them the go-to choice for engineers and manufacturers worldwide.