Microetching Solution for Copper Adhesion and Film Preservation
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Solution Overview
Problem
Conventional microetching solutions struggle to maintain uniform adhesion between copper layers and resins in the semi-additive process, especially when the copper layer thickness is reduced, leading to potential removal of the entire electroless plating film and defects in the plating resist pattern.
Innovation Solution
A microetching solution comprising an aqueous solution with cupric ions, organic acids, halide ions, polymers with polyamine chains or cationic groups, and nonionic surfactants, which are specifically formulated to ensure uniform surface roughening and adhesion even with low etching amounts, along with a replenishment solution to maintain component concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional microetching solutions are used to roughen the copper layer surface, then adhesion between the copper layer and resist is improved, but the entire electroless plating film may be removed when the copper layer thickness is reduced to 1 μm or less
Solution Approach 1:
The patent changes the chemical parameters of the microetching solution by specifying precise concentration ranges for cupric ions (0.01-5.0 g/L), organic acids (0.1-10.0 g/L), halide ions (0.01-1.0 g/L), polymers (0.001-0.5 g/L), and nonionic surfactants (0.001-0.1 g/L). These parameter adjustments enable controlled etching that forms sufficient surface irregularities for adhesion while limiting the etching depth to prevent complete film removal in thin copper layers
Solution Approach 2:
The patent creates a composite microetching solution system combining multiple chemical components (cupric ions, organic acids, halide ions, polymers with polyamine chains or cationic groups, and nonionic surfactants) that work synergistically. The polymer and surfactant components modify the etching behavior to achieve uniform surface roughening without excessive material removal, resolving the contradiction between adhesion improvement and film preservation
2Loss of substance
If the etching amount is decreased to prevent removal of the entire electroless plating film, then copper layer preservation is improved, but uniform adhesion between the electroless plating film and plating resist becomes difficult to secure
Solution Approach 1:
The patent optimizes the concentration parameters to achieve a balance where the etching amount is sufficient to create uniform surface irregularities for adhesion but limited to preserve the copper layer. The specific concentration ranges and ratios (A/B = 2000-9000, A/D = 500-9000) are designed to control etching depth while ensuring uniform surface roughening across the entire copper layer
Solution Approach 2:
The polymer and nonionic surfactant components act as intermediaries that mediate between the etching action and the copper layer. These additives control the etching process to produce uniform surface morphology that provides adequate adhesion sites without requiring deep etching, thus preserving the copper layer while ensuring uniform adhesion
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 maintains adhesion between copper layers and resins with reduced etching amounts, preventing the removal of the entire copper layer and ensuring uniformity in the plating resist pattern, thereby enhancing the productivity and quality of wiring boards.
Implementation Method 1
the copper layer surface is roughened by microetching with a microetching solution... an aqueous solution containing cupric ions
Implementation Method 2
a polymer and a nonionic surfactant... the polymer is a water-soluble polymer including a polyamine chain and/or a cationic group... adhesion between the copper layer surface and a resin
Implementation Method 3
a nonionic surfactant... adhesion between the copper layer surface and a resin can be uniformly maintained
Data Source
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AI summary
Disclosed is a microetching solution, a replenishment solution added to said microetching solution and a method for production of a wiring board using said microetching solution. The microetching solution for copper consists of an aqueous solution containing a cupric ion, an organic acid, a halide ion, a polymer and a nonionic surfactant. The polymer is a water-soluble polymer including a polyamine chain and/ or a cationic group and having a weight average molecular weight of 1000 or more. In the microetching solution of the present invention, a value of A/B is 2000 to 9000 and a value of A/D is 500 to 9000, where a concentration of the halide ion is A% by weight, a concentration of the polymer is B% by weight and a concentration of the nonionic surfactant is D% by weight. Using this microetching solution, adhesion to a resin or the like can be uniformly maintained even with a low etching amount.