Copper Wiring Etchant with Azole Compounds for Side Etching Control
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Solution Overview
Problem
Existing etchants for copper wiring in printed wiring boards cause side etching, leading to uneven copper wiring and reduced linearity, which affects the reliability of electrical insulation and impedance characteristics.
Innovation Solution
An aqueous etchant solution containing an acid, oxidizing metal ions, bromide ions, and specific compounds like aliphatic noncyclic, heterocyclic, and heteroaromatic compounds that capture cuprous ions to control etching direction and prevent side etching, maintaining wiring linearity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etchants (iron chloride-based, copper chloride-based, or alkaline etchants) are used, then etching process is simple and cost-effective, but side etching occurs causing copper wiring to become narrower from bottom to top
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by introducing specific compounds (azole compounds, aliphatic heterocyclic compounds, or their mixtures) in controlled concentrations (0.01-100 g/L). This parameter modification transforms the etchant's selective etching capability to prevent side etching while maintaining vertical etching direction, thus improving wiring width uniformity without complicating the manufacturing process
Solution Approach 2:
The patent creates a composite etchant system by combining conventional etchant components (acid, oxidizing metal ion, bromide ion) with specific organic compounds (azole, aliphatic heterocyclic). This composite formulation synergistically enhances the etchant's ability to distinguish between vertical and lateral etching paths, preventing side etching while maintaining process simplicity
2Manufacturing precision
If azole compounds are added to restrain side etching, then side etching is reduced, but copper wiring linearity deteriorates causing uneven side surfaces
Solution Approach 1:
The patent optimizes the concentration parameter of the heterocyclic compound within a specific range (0.01-100 g/L) to achieve the optimal balance between side etching restraint and side surface uniformity. By precisely controlling this parameter, the etchant effectively prevents side etching while maintaining smooth side surfaces and good wiring linearity
Solution Approach 2:
The patent applies local quality by using compounds that selectively interact with cuprous ions at specific locations during etching. The aliphatic heterocyclic compounds preferentially bind to cuprous ions that would otherwise cause side etching, while allowing controlled etching at the vertical interface, thus creating uniform side surfaces while restraining side etching
3Productivity
If etching is performed to form fine copper wiring patterns, then wiring density is increased, but side etching becomes more severe requiring complex etchant formulations
Solution Approach 1:
The patent modifies the etchant's chemical parameters by incorporating aliphatic heterocyclic compounds that specifically target cuprous ions. This parameter change enhances the etchant's selectivity for vertical etching paths, allowing fine wiring patterns to be formed with minimal side etching, thus achieving high wiring density while maintaining manufacturing precision
Solution Approach 2:
The aliphatic heterocyclic compound acts as an intermediary substance that mediates between the etchant's aggressive etching capability and the need for precise side etching control. It binds to cuprous ions and directs the etching reaction toward vertical paths only, enabling fine pattern formation without excessive side etching
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 solution effectively reduces side etching, maintains copper wiring linearity, and minimizes variations in wiring width, enhancing the reliability and yield of printed wiring boards.
Implementation Method 1
an etchant for copper, which is an aqueous solution including an acid, an oxidizing metal ion, a bromide ion, and one or more compounds
Implementation Method 2
one or more compounds selected from the group consisting of an aliphatic noncyclic compound, an aliphatic heterocyclic compound and a heteroaromatic compound... that capture cuprous ions to control etching direction
Data Source
AI summary
An etchant for copper includes an acid and one or more compounds selected from the group consisting of an aliphatic noncyclic compound, an aliphatic heterocyclic compound and a heteroaromatic compound. The aliphatic noncyclic compound is a saturated aliphatic noncyclic compound (A) including only two or more nitrogen atoms as heteroatoms, and 2 to 10 carbon atoms. The aliphatic heterocyclic compound is a compound (B) including a five-, six-, or seven-membered ring having one or more nitrogen atoms as one or more heteroatoms constituting the ring. The heteroaromatic compound is a compound (C) including a six-membered heteroaromatic ring having one or more nitrogen atoms as one or more heteroatoms constituting the ring.