Copper Foil Coating for PCB Adhesion and Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing copper foils for printed wiring boards face challenges in achieving high adhesiveness to insulating substrates and etching performance, particularly with fine pitch designs, while also being cost-effective and resistant to corrosion and heat. The use of Ni and Cr layers can improve these properties but often results in conflicting performance and high manufacturing costs due to inefficient sputtering targets.
Innovation Solution
A copper foil with a Ni-V alloy layer and a Cr layer of ultrathin thickness, where the Ni-V alloy layer contains 20 μg/dm2 to 600 μg/dm2 of Ni and V, and the Cr layer contains 15 μg/dm2 to 210 μg/dm2 of Cr, is applied to the surface, enhancing adhesiveness and etching performance while improving corrosion resistance and heat stability through a balanced coating layer configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a roughening treatment is performed to improve adhesiveness, then adhesiveness to insulating substrate is improved, but etching performance deteriorates and insulation reliability decreases
Solution Approach 1:
The invention extracts and removes the roughening treatment step from the conventional process. Instead of forming irregularities on the copper foil surface, the patent uses a smooth-surfaced copper foil, thereby eliminating the source of insulation deterioration while maintaining adhesiveness through alternative means (metallic coating layers).
Solution Approach 2:
The invention introduces metallic coating layers (Ni, Pd, Pt, or their alloys) as intermediary layers between the smooth copper foil surface and the insulating substrate. These coating layers serve as mediators that provide both adhesiveness to the substrate and good etching performance without requiring surface roughening.
2Strength
If a Cr layer is provided to improve adhesiveness, then adhesiveness to insulating substrate is improved, but etching performance deteriorates and etching residues are generated
Solution Approach 1:
The invention replaces the Cr layer (which causes etching residue problems) with alternative metallic coating layers made of Ni, Pd, Pt or their alloys. These alternative materials provide comparable or superior adhesiveness without the etching residue issue, effectively substituting a problematic material with better alternatives.
Solution Approach 2:
The invention uses composite metallic coating structures consisting of multiple layers with different compositions and thicknesses. By combining different metals (Ni, Pd, Pt, or their alloys) in specific configurations, the coating provides both high adhesiveness and excellent etching performance, avoiding the drawbacks of single-material Cr coatings.
3Reliability
If Ni and Cr layers are provided to improve adhesiveness and etching performance, then both properties are improved, but manufacturing cost increases due to inefficient sputtering targets
Solution Approach 1:
The invention uses sputtering targets that serve multiple functions: they provide the metallic coating material for both adhesiveness and corrosion resistance, while also being cost-effective and efficient. By selecting appropriate target materials and configurations, the process achieves multiple objectives simultaneously, including improved target efficiency and reduced manufacturing costs.
Solution Approach 2:
The invention optimizes various parameters including coating layer thickness, composition ratios, and sputtering conditions to achieve the best balance between performance and cost. By carefully controlling these parameters, the patent reduces material consumption and improves sputtering efficiency, thereby lowering manufacturing costs while maintaining high adhesiveness and etching performance.
4Strength
If coating layer thickness is increased to improve adhesiveness, then adhesiveness to insulating substrate is improved, but etching performance deteriorates
Solution Approach 1:
The invention optimizes the thickness parameter of the metallic coating layers to achieve the optimal balance between adhesiveness and etching performance. By controlling the coating thickness within specific ranges and using multiple thin layers instead of one thick layer, the patent maintains good adhesion while ensuring that etching can proceed effectively without excessive resistance from the coating.
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 copper foil achieves superior adhesiveness, etching performance, and corrosion resistance, maintaining stability even at high temperatures, while reducing manufacturing costs by optimizing the efficiency of sputtering targets and minimizing the thickness of the coating layers.
Implementation Method 1
when the coating layer is formed by sputtering
Data Source
AI summary
Provided is a copper foil for a printed wiring board, the copper foil being suitable for achieving finer pitch, favorable in terms of manufacturing cost, and excellent both in etching ability and adhesion to an insulating substrate. The copper foil for a printed wiring board comprises a copper foil base material and a covering layer for covering at least a portion of a surface of the copper foil base material, wherein the covering layer is formed by an nickel-vanadium alloy layer containing nickel and vanadium, and a chromium layer, laminated in this order from the surface of the copper foil base material; the chromium layer contains chromium in an amount of 15-210 μg/dm2; the nickel-vanadium alloy layer contains nickel and vanadium in a combined covering amount of 20-600 μg/dm2; and the nickel-vanadium alloy layer contains vanadium in an amount of 3-70 wt %.