Fine Grain Copper Foil Electrolyte for High Peeling Strength
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Solution Overview
Problem
Conventional copper foils for printed circuit boards face challenges in maintaining sufficient peeling strength, heat resistance, acid resistance, and preventing powder dropping, especially when used with high glass transition temperature epoxy substrates, while also requiring low roughness for fine circuit lines, and existing solutions either fail to meet these requirements or pose environmental concerns.
Innovation Solution
A copper foil manufacturing method involving an acidic copper sulfate solution with a trace of tungsten ionic compound is used for electroplating, ensuring uniform deposition on both peaks and deep valleys, followed by a thermal resistant layer, an alkali chromium antirust layer, and a silane coupling agent treatment to enhance adhesion and resistance without environmental hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If surface roughening treatment is conducted to enhance peeling strength between copper foil and high Tg substrate, then peeling strength is improved, but copper powder dropping and abnormal copper etching residues occur
Solution Approach 1:
The invention changes the chemical composition parameters of the electrolyte solution by adding specific metal ions (nickel ions at 0.01-10g/L and cobalt ions at 0.01-10g/L) to the acidic copper sulfate electrolyte. This parameter modification enables the electrolyte to deposit copper with appropriate surface roughness that provides sufficient peeling strength without causing copper powder dropping or etching residues, thus resolving the contradiction between peeling strength improvement and harmful factor prevention.
2Strength
If surface roughness is increased to improve peeling strength with high Tg substrate, then peeling strength is enhanced, but etching characteristics deteriorate
Solution Approach 1:
The invention modifies the electrolyte composition by incorporating nickel ions and cobalt ions alongside copper sulfate, which changes the deposition characteristics of the copper layer. This compositional parameter change produces a surface roughness profile that enhances peeling strength while maintaining proper etching characteristics, preventing the deterioration that would normally occur with increased roughness.
3Manufacturing precision
If low roughness copper foil is used for high density and fine circuit lines, then manufacturing precision is improved, but lamination peeling strength deteriorates
Solution Approach 1:
The invention changes the electrolyte composition by adding nickel ions and cobalt ions to the acidic copper sulfate solution, which modifies the surface morphology of the deposited copper layer. This parameter modification enables the formation of a fine-grained surface structure with controlled roughness that maintains both the manufacturing precision required for fine circuit lines and sufficient lamination peeling strength, thus resolving the contradiction between these two requirements.
4Strength
If arsenic, antimony, bismuth or selenium are added to electrolyte solution for effective copper roughening treatment, then heat resistant peeling strength is improved, but environmental protection problems arise
Solution Approach 1:
The invention replaces toxic elements (arsenic, antimony, bismuth, selenium) with non-toxic nickel ions and cobalt ions in the electrolyte solution. This substitution converts a harmful process (using toxic substances) into a beneficial one (using environmentally friendly substances), achieving the same heat resistant peeling strength improvement without creating wastewater treatment problems or environmental pollution.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by substituting toxic metal ions with nickel and cobalt ions. This parameter change maintains the effectiveness of the roughening treatment for improving heat resistant peeling strength while eliminating the environmental harm associated with toxic substance usage and wastewater treatment requirements.
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 achieves high peeling strength, heat resistance, acid resistance, and low powder dropping with improved etching characteristics, suitable for various printed circuit boards, while avoiding the use of toxic elements and ensuring efficient electroplating with environmental benefits.
Implementation Method 1
the electrochemical deposition of copper sulfate electrolyte on the copper drum surface of the cathode to electroplate copper on the original foil
Implementation Method 2
an acidic copper sulfate solution with a trace of tungsten ionic compound is used for electroplating, ensuring uniform deposition on both peaks and deep valleys
Implementation Method 3
a silane coupling agent treatment to enhance adhesion and resistance without environmental hazards
Data Source
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AI summary
The present invention relates to a manufacturing method for a fine grain surface copper foil with the low roughness, high peeling strength, high chemical resistance, high heat resistance, high resistance to moisture absorption and good etching properties, and applicable to all kinds of printed circuit boards to provide a solution to the conventional problems of electrolysis processing known to the past, which includes the special electrolysis composition and special steps, the copper tumor deposits not only on peaks, but also effectively and uniformly in the deep valley position of copper foil; the formed copper tumors are of small size and large quantity; in the low roughness conditions, the resulted fine grain surface copper foil still has the characteristics to meet a varity of the copper foil requirements, applicable to all types of printed circuit boards. The technical characteristics are that the adhesion surface of copper foil is electroplated in an electroplating bath composed of copper sulfate, sulfuric acid, sodium phosphotungstate compounds to obtain a roughening treament layer which is then treated with a electroplating copper foil method for anti-rust and thermoresistance known to the art to get a Zn alloy thermoresistant layer; The resulted thermoresistant layer is plated with an alkali chromium based antirust layer which is finally coated a silane coupling agent treatment layer. The copper foil surface roughening treatment uses no toxic arsenic element, meanwhile exhibits high plating efficiency, short time performances with the advantages of both environmental protection and high speed.