Comparison of Paper-based and fiberglass-based insulation laminates and Copper Clad Laminates ( CCL )

Technical Comparison of Paper-Based, Fabric-Based and Fiberglass-Based Insulation Laminates and Copper Clad Laminates (CCL)

From the perspective of resin formulation and impregnation process.

This document is prepared from the perspective of an insulation laminate and copper clad laminate (CCL) resin formulation and impregnation process specialist. It focuses on resin systems, raw materials, and processing mechanisms, with emphasis on engineering principles rather than market-level descriptions.

1. Fundamental Differences from a System Perspective

The essence of insulation laminates and CCL is a composite system made of:

Reinforcement structure x resin chemistry x impregnation/curing mechanism

2. Fundamental Differences from the Resin System Perspective

2.1 Paper-Based Insulation Laminates

(1) Typical resin system

• Phenolic resin (PF): dominant and almost exclusive
• Minor modifications:
• Urea-modified phenolic
• Alcohol-soluble or water-soluble phenolic

(2) Resin formulation characteristics

• Base-catalyzed condensation polymerization
• Broad molecular-weight tolerance
• Typical solid content: 45-55%
• Low viscosity to ensure full paper impregnation

(3) Resin-paper interaction mechanism

• Resin does not only coat surface; it penetrates and fills the fiber network
• Phenolic resin infiltrates cellulose capillary structure
• After curing, it forms a quasi-homogeneous composite structure

(4) Engineering conclusion

Paper-based laminates require relatively low chemical-performance capability from resin, but very high impregnation capability.

2.2 Fabric-Based Insulation Laminates (Cotton / Fabric)

(1) Typical resin systems

• Phenolic resin (PF): mainstream
• Epoxy resin (EP): mid/high-grade products
• PF/EP hybrid systems: limited scenarios

(2) Resin formulation and processing features

Compared with paper-based systems:

• Higher solid content (typically 50-60%)
• Higher viscosity
• Higher requirement for rheological stability

Resin must balance:

• Penetration into fabric pores
• Retention on fabric surface

(3) Reinforcement structure characteristics

• Fabric is a woven structure
• Typical void structures:
• Warp and weft interlacing pores
• Inter-bundle voids
• Resin must both penetrate and remain

(4) Engineering nature

Fabric-based laminates follow a structural-component design philosophy. Resin is both an insulating medium and a load-bearing bonding phase.

2.3 Fiberglass-Based Materials

This category is the core material system of electronic-grade CCL.

2.3.1 Main resin system classifications

2.3.2 Fundamental shift in resin formulation

Resin formulation is no longer a simple "resin + curing agent" issue. It becomes a reaction-system engineering problem, involving:

• Molecular-weight distribution
• Reaction activity window
• Controlled B-stage behavior

2.3.3 Critical resin parameters

• Gelling time
• B-stage tack window
• Exothermic reaction rate
• Volatile content control

2.3.4 Resin-fiberglass interface considerations

• Fiberglass is an inorganic material
• Effective bonding depends on:
• Silane coupling agents
• Surface treatment system
• Chemical affinity between resin and fiberglass is critical

In fiberglass systems, resin is not only a filler; it is a key determinant of dielectric performance and long-term reliability.

3. Differences from the Impregnation Process Perspective

3.1 Comparison of impregnation methods

3.2 Differences in prepreg (PP) state

Paper-based

• No strict independent "prepreg" concept
• Often laminated directly after impregnation

Fabric-based

• Semi-cured sheet form
• Wider process tolerance

Fiberglass-based

• Prepreg is an independent engineered product
• Resin flow, gel time, and surface condition must be quantitatively controlled

4. Engineering Logic Behind Final Product Classification

4.1 Insulation laminates (without copper)

4.2 Copper-clad laminates (CCL)

5. One-Sentence Engineering Summary (Resin Perspective)

• Paper-based systems: resin determines whether complete impregnation is achievable.
• Fabric-based systems: resin determines mechanical strength and structural stability.
• Fiberglass-based systems/CCL: resin determines dielectric performance, reliability, and final product grade.