Cupric Nitrile Microetching Composition for PCB Copper Adhesion
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Solution Overview
Problem
Existing microetching compositions for copper and copper alloy surfaces in printed circuit board manufacturing often result in excessive etching, instability, and inadequate bonding strength, which can lead to fluctuations in etching rates and metal discoloration, affecting the quality and longevity of the bonding process.
Innovation Solution
A cupric ion-based microetching composition incorporating nitriles, such as acetonitrile or adiponitrile, along with a source of halide ions and an acid, is used to control the etching depth and enhance surface roughness, improving adhesion between copper surfaces and resin layers while minimizing metal removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional microetching compositions (hydrogen peroxide and inorganic acid) are used, then etching capability is achieved, but etching rate fluctuates and metal discoloration occurs due to hydrogen peroxide decomposition
Solution Approach 1:
The patent changes the chemical composition parameters by replacing hydrogen peroxide with cupric ion sources and adding nitrile compounds. This parameter change stabilizes the etching rate while maintaining etching capability, eliminating the decomposition issues of hydrogen peroxide.
Solution Approach 2:
The patent uses cupric ion sources that can be easily replenished and nitrile compounds that provide stable, controllable etching. These materials offer more reliable and consistent performance compared to the unstable hydrogen peroxide system.
2Reliability
If cupric ion-based etching solutions are used, then stable etching is achieved, but copper surfaces are etched more deeply than desired
Solution Approach 1:
The patent modifies the etching solution by adding nitrile compounds (acetonitrile, adiponitrile, or other dialkyl nitriles) to the cupric ion-based solution. This parameter change reduces the etching depth while maintaining solution stability, achieving the desired microetching effect without excessive copper removal.
Solution Approach 2:
The nitrile compounds act as intermediaries that moderate the etching action of cupric ions. They provide a buffering effect that controls the etching rate and depth, preventing excessive etching while maintaining the stability benefits of cupric ion-based solutions.
3Strength
If deeper etching is performed to improve adhesion, then bonding strength increases, but more metal is removed reducing circuit trace integrity
Solution Approach 1:
The patent changes the etching parameters by using cupric ion sources combined with nitrile compounds, which provide optimal surface roughness for adhesion while minimizing copper removal. This achieves the desired bonding strength improvement without excessive metal loss.
Solution Approach 2:
The patent applies partial etching action through controlled microetching that creates sufficient surface roughness for mechanical interlocking with resin, but stops before removing excessive copper. The nitrile-modified solution enables this precise control over the etching action.
4Strength
If extended microetching treatment is applied to improve adhesion, then bonding strength increases, but metal builds up in the composition reducing its usable life
Solution Approach 1:
The patent modifies the composition parameters by using cupric ion sources with nitrile compounds, which reduce metal buildup in the solution. This extends the usable life of the microetching composition while maintaining effective adhesion promotion capabilities.
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 composition significantly reduces copper etching depth, maintains effective adhesion promotion, and extends the usable life of the microetching solution by limiting metal consumption, making it suitable for multilayer printed circuit board production.
Implementation Method 1
surface roughness is provided to the copper surface by depositing an oxide layer on the copper surface, such as cuprous oxide, cupric oxide
Implementation Method 2
A cupric ion-based microetching composition incorporating nitriles, such as acetonitrile or adiponitrile, along with a source of halide ions and an acid
Implementation Method 3
Another type of microetching solution utilizes a cupric ion source, an organic acid, and a halide ion source
Data Source
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AI summary
The present invention is directed to a microetching composition comprising a source of cupric ions, acid, a nitrile compound, and a source of halide ions. Other additive, including organic solvents, a source of molybdenum ions, amines, polyamines, and acrylamides may also be included in the composition of the invention. The present invention is also directed to a method of microetching copper or copper alloy surfaces to increase the adhesion of the copper surface to a polymeric material, comprising the steps of contacting a copper or copper alloy surface with the composition of the invention, and thereafter bonding the polymeric material to the copper or copper alloy surface.