Adhesive Layer: Thickness 12.5-50 μm, Peel Strength ≥0.8 N/mm

Component Specifications

Definition

The adhesive layer in flexible printed circuit boards (FPCBs) is a critical component that bonds the conductive copper layers to the flexible polyimide substrate, ensuring mechanical integrity, electrical insulation, and thermal stability. It prevents delamination under bending, vibration, and thermal cycling while maintaining signal integrity in high-frequency applications.

Working Principle

The adhesive layer functions through thermosetting or thermoplastic bonding mechanisms, creating a permanent or reworkable bond between the copper foil and polyimide film. During lamination under heat and pressure, it flows to fill micro-voids, then cures to form a durable, insulating bond that withstands mechanical stress and thermal expansion differences.

Materials

Typically composed of epoxy, acrylic, or polyimide-based adhesives with controlled viscosity, glass transition temperature (Tg 120-200°C), and dielectric constant (Dk 3.0-4.0). May contain silica fillers for thermal conductivity enhancement.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Thickness	12.5-50 μm
Peel Strength	≥0.8 N/mm
Volume Resistivity	≥10^14 Ω·cm
Dielectric Strength	≥100 V/μm
Thermal Conductivity	0.2-0.5 W/m·K
Operating Temperature	-40°C to +150°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IPC-4203, IPC-4204, ISO 9001, UL 94 V-0

Parent Products

This component is used in the following industrial products

Flexible PCB

A flexible printed circuit board that can bend and conform to various shapes while maintaining electrical connectivity.

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Engineering Analysis

Risks & Mitigation

Delamination under thermal cycling
Moisture-induced adhesive degradation
Adhesive flow causing electrical shorts
Reduced flexibility from thick adhesive layers

FMEA Triads

Trigger: Incomplete adhesive curing during lamination
Failure: Reduced bond strength leading to layer separation
Mitigation: Implement precise temperature/pressure profiling and post-cure verification testing

Trigger: Moisture absorption in hygroscopic adhesives
Failure: Void formation and reduced dielectric strength during reflow
Mitigation: Use moisture-resistant adhesive formulations and controlled storage with desiccants

Trigger: CTE mismatch between adhesive and substrate
Failure: Mechanical stress cracking during temperature cycling
Mitigation: Select adhesives with CTE closely matching copper and polyimide (15-20 ppm/°C)

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Thickness tolerance ±10%, alignment tolerance ±50 μm

Test Method

IPC-TM-650 Method 2.4.9 for peel strength, IPC-650 Method 2.5.5 for dielectric withstand, thermal shock testing per IPC-9701

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Adhesive Layer

1 company lists this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

Yijing Brakes

Shandong, CN

Also makes: Brake Shoe, Automotive Components, Brake Pad

Listed on the company's own website · profile compiled by CNFX from public sources

Listed there as: “4. Adhesive Layer”
View source page ↗ yijingbrakes.com · checked 2026-08-28

View profile Send enquiry

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the primary function of the adhesive layer in flexible PCBs?

The adhesive layer primarily provides mechanical bonding between copper conductors and the polyimide substrate while ensuring electrical insulation and preventing delamination during flexing.

How does adhesive selection affect flexible PCB performance?

Adhesive selection impacts flexibility, thermal resistance, dielectric properties, and reliability. High-Tg adhesives withstand reflow soldering, while low-modulus adhesives enhance bend durability.

What are common failure modes in adhesive layers?

Common failures include adhesive degradation from moisture absorption, thermal cycling fatigue, chemical corrosion from fluxes, and mechanical cracking during dynamic flexing.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Adhesive Layer