Etching Composition for Printed-Wiring Board Micro Wiring
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Solution Overview
Problem
Conventional etching solutions for semi-additive printed-wiring board production inadequately control the dissolution rate of chemical copper plating, leading to reduced wiring width and potential undercut issues, making it difficult to form micro wiring.
Innovation Solution
An etching composition comprising hydrogen peroxide, sulfuric acid, phenylurea, halogen ion, and tetrazoles, with a specific ratio of dissolution rates for chemical and electrolytic copper plating, is used to efficiently remove the chemical copper plating seed layer, maintaining wiring width and preventing undercut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional etching solution is used, then the etching process can be performed, but the dissolution rate of chemical copper plating is not sufficiently controlled, leading to excessive dissolution and wiring width reduction
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentrations of multiple etching agents (hydrogen peroxide: 0.1-5%, sulfuric acid: 0.1-10%, nitric acid: 0.01-5%) and additives (phenylurea: 0.001-0.3%, tetrazoles: 0.003-0.3%, halogen ions: 0.01-10 ppm) to achieve a dissolution rate ratio (Y/X) of 2-10, thereby controlling the etching speed to prevent wiring width reduction while maintaining etching efficiency
Solution Approach 2:
The patent uses a composite etching solution containing multiple chemical components (hydrogen peroxide, sulfuric acid, nitric acid, phenylurea, tetrazoles, and halogen ions) that work synergistically to achieve selective dissolution of chemical copper plating while minimizing damage to electrolytic copper plating, thus resolving the contradiction between etching speed and wiring width control
2Productivity
If the dissolution rate of chemical copper plating is increased to remove the seed layer efficiently, then the seed layer removal is improved, but excessive dissolution occurs causing undercut and wiring disappearance
Solution Approach 1:
The patent applies local quality by creating a selective etching environment where the etching solution exhibits different dissolution rates for different types of copper plating: high dissolution rate (Y) for chemical copper plating (seed layer) and low dissolution rate (X) for electrolytic copper plating (wiring), achieving a ratio Y/X of 2-10. This allows efficient seed layer removal while preserving wiring integrity and preventing undercut
Solution Approach 2:
The patent introduces intermediary substances (phenylurea and tetrazoles as additives, along with halogen ions) that mediate the etching process by selectively influencing the dissolution behavior of chemical copper plating versus electrolytic copper plating, enabling differential etching rates that protect wiring form integrity while removing the seed layer efficiently
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 etching composition effectively suppresses wiring width decrease and prevents undercut, enabling the formation of micro wiring in semi-additive processes by optimizing the dissolution rates of chemical and electrolytic copper platings.
Implementation Method 1
an etching composition... which comprises 0.2 to 5% by mass of hydrogen peroxide... wherein the ratio of the dissolution rate of the chemical copper plating (Y) to the dissolution rate of an electrolytic copper plating (X) at a liquid temperature of 30° C. (Y/X) is 4 to 7
Implementation Method 2
an etching composition... which comprises 0.5 to 10% by mass of sulfuric acid... wherein the ratio of the dissolution rate of the chemical copper plating (Y) to the dissolution rate of an electrolytic copper plating (X) at a liquid temperature of 30° C. (Y/X) is 4 to 7
Data Source
AI summary
The present invention can provide an etching composition for a chemical copper plating for the production of a printed-wiring board according to a semi-additive process, which comprises 0.2 to 5% by mass of hydrogen peroxide, 0.5 to 10% by mass of sulfuric acid, 0.001 to 0.3% by mass of phenylurea, 0.1 to 3 mass ppm of halogen ion and 0.003 to 0.3% by mass of tetrazoles, and wherein the ratio of the dissolution rate of the chemical copper plating (Y) to the dissolution rate of an electrolytic copper plating (X) at a liquid temperature of 30° C. (Y/X) is 4 to 7.