Surface-Treated Copper Foil Blister Suppression

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Solution Overview

Problem

Copper-clad laminate boards treated with silane coupling agents for enhanced adhesiveness tend to form blisters under high-temperature thermal loads, leading to deformation and detachment of electronic components during reflow soldering, which compromises the reliability and quality of printed circuit boards.

Innovation Solution

Control the concentrations of N, C, and Si/O atomic percentages in the depth profile of the surface-treated copper foil to achieve optimal adhesiveness at ordinary temperatures while suppressing blister formation under thermal loads, using techniques such as silane coupling agent treatments with specific concentrations and stirring times, and potentially combining these with roughening, heat resistance, or chromate treatments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the surface of the copper foil is treated with a silane coupling agent to enhance adhesiveness, then the adhesiveness to an insulating substrate is improved, but blister formation occurs under high-temperature thermal loads during reflow soldering

Engineering Contradiction:
Improveadhesiveness to insulating substrateVSAvoidblister formation under thermal load
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the concentration of the silane coupling agent and the stirring time during the surface treatment process. By optimizing these parameters, the invention achieves good adhesiveness at ordinary temperatures while suppressing blister formation under high-temperature thermal loads during reflow soldering.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by performing a surface treatment with a silane coupling agent before the reflow soldering process. This preliminary treatment prepares the copper foil surface to have both good adhesiveness and resistance to blister formation under subsequent high-temperature thermal loads.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the N concentration and Si concentration on the surface of the copper foil are controlled by treating with a silane coupling agent, then the adhesiveness is enhanced, but the copper-clad laminate board generates blister due to thermal load at 300°C or more

Engineering Contradiction:
Improveadhesiveness to insulating substrateVSAvoidresistance to thermal load at 300°C or more
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by precisely controlling the concentration of the silane coupling agent and the stirring time during the surface treatment process. By optimizing these parameters, the invention achieves good adhesiveness at ordinary temperatures while suppressing blister formation under high-temperature thermal loads during reflow soldering.

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 controlled surface treatment enhances adhesiveness to insulating substrates at ordinary temperatures and significantly reduces blister formation during thermal loading, ensuring high-quality and reliable printed circuit boards with improved high-frequency performance.

Implementation Method 1

the adhesiveness to an insulating substrate of the copper foil is enhanced by treating the surface of the copper foil with a silane coupling agent

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

an N concentration of from 1.5 to 7.5 atomic % by an XPS measurement at a depth after sputtering from the surface-treated surface for 0.5 min at a rate of 1.1 nm/min (SiO2 conversion)

Methodology Applied
Scientific EffectX-ray Photoelectron Spectroscopy: Photoelectric Effect

Implementation Method 3

by an XPS measurement at a depth after sputtering from the surface-treated surface for 0.5 min at a rate of 1.1 nm/min (SiO2 conversion)

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentUS10383222B2Surface-treated copper foil
Publication Date: 2019.08.13 JX NIPPON MINING & METALS CORP

AI summary

To provide a surface-treated copper foil that is excellent in adhesiveness to an insulating substrate at ordinary temperature, and is capable of suppressing the formation of blister on application of a thermal load of reflow soldering to a copper-clad laminate board constituted by the copper foil. A surface-treated copper foil having a surface-treated surface, the surface-treated copper foil satisfying one or more of the following conditions (1) to (3): by an XPS measurement at a depth after sputtering from the surface-treated surface for 0.5 min at a rate of 1.1 nm/min (SiO2 conversion), (1) the N concentration is from 1.5 to 7.5 atomic %; (2) the C concentration is from 12 to 30 atomic %; and (3) the Si concentration is 3.1 atomic % or more and the O concentration is from 40 to 48 atomic %.