INDUSTRY COMPONENT

Prepreg

Prepreg is a fiber-reinforced polymer composite material used as an insulating layer in multilayer printed circuit boards (PCBs).

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Component Specifications

Definition
Prepreg (pre-impregnated composite fibers) is a semi-cured thermosetting resin matrix reinforced with woven or non-woven fiberglass fabric. In multilayer PCB manufacturing, it serves as the dielectric insulating layer between copper-clad laminates, bonding them together during lamination under heat and pressure. The material undergoes partial curing (B-stage) during production, allowing it to flow and fully cure (C-stage) during PCB fabrication to form a solid, insulating bond.
Working Principle
Prepreg works by utilizing a partially cured thermosetting resin (typically epoxy) impregnated into fiberglass reinforcement. During PCB lamination, heat (typically 180-200°C) and pressure (200-400 psi) cause the resin to flow, wetting adjacent copper layers and core materials, then fully polymerize into a rigid, insulating dielectric layer that bonds the PCB layers together while providing electrical insulation and mechanical stability.
Materials
Fiberglass fabric (E-glass, NE-glass, or low-loss glass) impregnated with thermosetting resin (epoxy, polyimide, BT, or cyanate ester), with flame retardant additives (brominated or halogen-free) to meet UL94 V-0 standards. Typical resin content: 40-60%, glass transition temperature (Tg): 130-180°C, dielectric constant (Dk): 3.5-4.5 at 1 GHz.
Technical Parameters
  • Df 0.015-0.025 at 1 GHz
  • Dk 3.8-4.2
  • Tg 140-170°C
  • CTE 40-60 ppm/°C
  • Flow 15-30%
  • Gel Time 60-120 seconds at 170°C
  • Thickness 0.05-0.2 mm
  • Resin Content 45-55%
Standards
IPC-4101, IPC-4103, ISO 9001, UL 94

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Prepreg.

PCB prepreg multilayer PCB material dielectric layer fiberglass epoxy PCB lamination prepreg specifications high-frequency PCB materials Prepreg Prepreg in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

Multilayer PCB

A printed circuit board consisting of multiple conductive copper layers separated by insulating dielectric materials, laminated together to form a single integrated board.

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Engineering Analysis

Risks & Mitigation
  • Moisture absorption causing delamination
  • Incomplete resin flow during lamination
  • Thermal degradation during multiple lamination cycles
  • Inconsistent dielectric properties
FMEA Triads
Trigger: Improper storage conditions leading to moisture absorption
Failure: Void formation and delamination during lamination
Mitigation: Implement controlled storage (-5°C to 5°C) with moisture barrier packaging and monitor shelf life
Trigger: Incorrect lamination temperature or pressure profiles
Failure: Incomplete resin flow and poor interlayer bonding
Mitigation: Validate lamination profiles through TMA/DSC testing and implement SPC for process control
Trigger: Resin chemistry variations between batches
Failure: Inconsistent dielectric properties and impedance control
Mitigation: Implement incoming material testing for Dk/Df and establish supplier quality agreements

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Thickness tolerance: ±10%, Dielectric constant tolerance: ±0.2
Test Method
IPC-TM-650 test methods for dielectric properties, thermal analysis (TMA/DSC), and mechanical testing per IPC-4101

Buyer Feedback

★★★★☆ 4.9 / 5.0 (14 reviews)

"Testing the Prepreg now; the technical reliability results are within 1% of the laboratory datasheet."

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

"As a professional in the Computer, Electronic and Optical Product Manufacturing sector, I confirm this Prepreg meets all ISO standards."

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Frequently Asked Questions

What is the difference between prepreg and core material in PCBs?

Core material is fully cured copper-clad laminate with copper on both sides, while prepreg is partially cured dielectric material without copper, used to bond cores together during lamination.

How does prepreg thickness affect PCB performance?

Prepreg thickness controls dielectric spacing between copper layers, affecting impedance control, signal integrity, and thermal management in high-frequency and high-speed PCB designs.

What are the storage requirements for prepreg?

Prepreg must be stored at -5°C to 5°C in moisture-barrier packaging with desiccant, with limited shelf life (typically 3-6 months) to prevent premature curing and moisture absorption.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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Precision Resistors Prepreg Layer