Ni-Controlled Electroless Plating for Low-Loss Copper Clad Laminates

Solution Overview

Problem

Existing methods for producing flexible circuit boards with copper clad laminates face challenges in achieving high adhesion between low dielectric resin films and electroless copper plating layers while maintaining low transmission loss and volume resistivity, particularly at high frequencies.

Innovation Solution

A copper clad laminate is developed with a low dielectric resin film and an electroless copper plating layer containing 0.01 to 1.2 wt% Ni, having a volume resistivity of 6.0 μΩ·cm or lower, and an average surface roughness of 1 to 150 nm, with optional electrolytic copper plating, and a production method involving surface modification and heating steps to enhance adhesion and deposition properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If electroless copper plating is applied on low dielectric resin film, then adhesion between resin film and copper layer is improved, but volume resistivity increases and transmission loss occurs

Engineering Contradiction:

ImproveadhesionVSAvoidvolume resistivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the Ni content in the electroless copper plating layer to 0.01 to 1.2 wt% and the Cu content to 98.8 to 99.99 wt%, along with controlling the thickness to 1 to 10 μm. These parameter optimizations resolve the contradiction by achieving both adequate adhesion and low volume resistivity (6.0 μΩ·cm or lower), thereby reducing transmission loss while maintaining electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

2Strength

If Ni content in electroless copper plating layer is increased to improve deposition properties, then adhesion is improved, but volume resistivity increases and magnetism occurs

Engineering Contradiction:

ImproveadhesionVSAvoidvolume resistivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the Ni content in the electroless copper plating layer to 0.01 to 1.2 wt% and the Cu content to 98.8 to 99.99 wt%, along with controlling the thickness to 1 to 10 μm. These parameter optimizations resolve the contradiction by achieving both adequate adhesion and low volume resistivity (6.0 μΩ·cm or lower), thereby reducing transmission loss while maintaining electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If sputtering process is used to form copper layer, then conductivity is improved, but production complexity and cost increase

Engineering Contradiction:

ImproveconductivityVSAvoidproduction process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical sputtering process with a chemical electroless plating process. This substitution eliminates the need for complex vacuum equipment and mechanical sputtering apparatus, simplifying the production process while achieving adequate conductivity through controlled chemical deposition of copper with specific Ni content (0.01 to 1.2 wt%) to ensure low volume resistivity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If electroless copper plating is applied to achieve low production cost, then productivity is improved, but adhesion and volume resistivity deteriorate

Engineering Contradiction:

Improveproduction efficiencyVSAvoidvolume resistivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the Ni content in the electroless copper plating layer to 0.01 to 1.2 wt% and the Cu content to 98.8 to 99.99 wt%, along with controlling the thickness to 1 to 10 μm. These parameter optimizations resolve the contradiction by achieving both adequate adhesion and low volume resistivity (6.0 μΩ·cm or lower), thereby reducing transmission loss while maintaining electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution achieves high adhesion and low transmission loss, enabling the production of flexible circuit boards with improved conductivity and reduced impedance variations, suitable for high-frequency applications.

Implementation Method 1

an electroless copper plating layer which is laminated on at least one surface of the low dielectric resin film

Methodology Applied

Scientific EffectElectroless plating:

Implementation Method 2

electroless copper plating layer having a volume resistivity of 6.0 μΩ·cm or lower

Methodology Applied

Scientific EffectChemical reduction:

Implementation Method 3

a dielectric loss that occurs in such a circuit board is known to be proportional to the product of three elements consisting of 'the frequency of a signal,' 'a square root of a dielectric constant of a board material' and 'a dissipation factor'

Methodology Applied

Scientific EffectDielectric loss:

Implementation Method 4

a material having a low transmission loss (dielectric loss) in a high frequency range is required for a circuit board

Methodology Applied

Scientific EffectElectromagnetic signal transmission:

Data Source

PatentUS12402253B2Copper clad laminate and method for producing the same

Publication Date: 2025.08.26 TOYO KOHAN CO LTD

AI summary

A copper clad laminate of the present invention includes a low dielectric resin film having a relative permittivity of 3.5 or lower and a dissipation factor of 0.008 or lower at a frequency of 10 GHz, and an electroless copper plating layer laminated on at least one surface of the low dielectric resin film. A Ni content in the electroless copper plating layer is 0.01 to 1.2 wt %, and the electroless copper plating layer has a volume resistivity of 6.0 μΩ·cm or lower. The copper clad laminate is capable of achieving a good volume resistivity at an electroless copper plating layer of a low dielectric resin film while suppressing a transmission loss when being applied to a flexible circuit board.