Copper Foil Laminate Surface Chemistry for Low-Pressure Resin Adhesion

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Solution Overview

Problem

The low reactivity of polyvinyl acetal resin with copper foil during lamination at low temperature and pressure results in poor adhesion between the copper foil and resin film, making it difficult to form a laminate with sufficient bonding.

Innovation Solution

Control the amount of metal components on the treated surface of the copper foil within a specific range (30-40 atomic %) to enhance the adhesion between the copper foil and polyvinyl acetal resin film, using surface treatments like rust proofing and roughening to improve infiltration properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If lamination is performed under low temperature and pressure conditions, then energy consumption is reduced and manufacturing efficiency is improved, but adhesion between copper foil and resin film deteriorates

Engineering Contradiction:
Improveenergy consumptionVSAvoidadhesion
Core Design Contradiction:
Use of energy by stationary objectVSStrength

Solution Approach 1:

The invention changes the chemical composition parameters of the resin film by incorporating carboxylic acid groups (specifically polyacrylic acid or carboxymethyl cellulose) to increase the amount of carboxylic acid groups on the copper foil surface. This chemical modification enables strong adhesion between the copper foil and polyvinyl acetal resin film under low temperature and pressure lamination conditions, resolving the contradiction between energy consumption and adhesion strength.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If polyvinyl acetal resin is used for lamination, then light transmission properties are improved, but reactivity with copper foil decreases leading to poor adhesion

Engineering Contradiction:
Improvelight transmissionVSAvoidadhesion
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

The invention introduces carboxylic acid groups (polyacrylic acid or carboxymethyl cellulose) as intermediary substances that mediate the bonding between copper foil and polyvinyl acetal resin film. These carboxylic acid groups form strong chemical bonds with copper foil while also being compatible with the polyvinyl acetal resin, enabling effective adhesion without compromising the light transmission properties of the polyvinyl acetal resin.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If copper foil surface is treated with rust proofing treatments, then corrosion resistance is improved, but adhesion with resin film deteriorates

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidadhesion
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention modifies the surface chemistry parameters of the copper foil by introducing carboxylic acid groups through treatment with polyacrylic acid or carboxymethyl cellulose. This chemical modification maintains corrosion resistance while creating a surface that strongly adheres to polyvinyl acetal resin film, resolving the contradiction between corrosion resistance and adhesion.

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 method ensures excellent adhesion between the copper foil and resin film, allowing for effective lamination under low temperature and pressure conditions, resulting in a laminate with improved bonding strength.

Implementation Method 1

enhance the adhesion between the copper foil and polyvinyl acetal resin film

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

surface treatments like rust proofing and roughening to improve infiltration properties

Methodology Applied
Scientific EffectRoughening: Abrasion

Data Source

PatentEP4296051B1Method for producing laminate and heating element, and defroster
Publication Date: 2025.08.27 MITSUI MINING & SMELTING CO LTD

AI summary

Provided is a method for manufacturing a laminate that is excellent in adhesion between the copper foil and the resin film while using a polyvinyl acetal resin having low reactivity with the copper foil. This method includes the steps of providing a copper foil having on at least one side a treated surface on which an amount of metal components is 30 atomic % or more and 40 atomic % or less, and attaching or forming a polyvinyl acetal resin film on the treated surface of the copper foil to form a laminate. The amount of metal components is a proportion of Cr, Ni, Cu, Zn, Mo, Co, W, and Fe in a total amount of N, O, Si, P, S, Cl, Cr, Ni, Cu, Zn, Mo, Co, W, and Fe when the treated surface is subjected to elemental analysis by X-ray photoelectron spectroscopy (XPS).