Circuit Board Narrow Wiring via Electroplating and Silver Recovery
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Solution Overview
Problem
Existing methods for manufacturing circuit boards, such as subtractive and semi-additive processes, face challenges with copper wiring undercut and environmental pollution, especially when producing narrow lines and spaces, and result in copper waste.
Innovation Solution
A method involving the use of photosensitive resin layers with silver particles, where the resin is exposed and developed to form conductive blocks, and then electroplated copper is applied only to the widened ends of these blocks, eliminating the need for etching and reducing material waste and pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the subtractive method is used to manufacture circuit boards with narrow lines and spaces, then the wiring patterns can be formed, but the copper wirings undergo undercut during etching and copper waste is generated
Solution Approach 1:
The patent inverts the conventional subtractive etching approach by using a semi-additive method where copper is selectively deposited only in desired wiring areas through electroplating, rather than removing copper from all areas. This inversion eliminates undercut issues and copper waste by building up conductive patterns additively instead of subtractively
Solution Approach 2:
The patent extracts and removes the harmful etching process entirely from the manufacturing flow. By using electroplating to directly form copper wirings on the substrate without subsequent etching, the method eliminates both the undercut problem and copper waste generation associated with traditional subtractive etching
2Manufacturing precision
If the semi-additive method is used to avoid undercut in copper wirings, then wiring precision is improved, but the copper electroplating process causes environmental pollution
Solution Approach 1:
The patent implements silver particle recovery by collecting and reusing the silver particles separated from the photosensitive resin layer after development. This recovery process reduces material waste and minimizes environmental pollution by preventing silver waste discharge while maintaining the benefits of the semi-additive method
Solution Approach 2:
The patent modifies the photosensitive resin composition by incorporating silver particles with specific size ranges (0.5-5 μm) and controlling their distribution. This parameter change enables the resin to form precise wiring patterns through selective exposure and development, achieving high precision while allowing for particle recovery and reduced environmental impact
3Area of moving object
If the wiring patterns need narrow lines and spaces, then component density increases, but the etching process causes undercut and precision is reduced
Solution Approach 1:
For narrow lines and spaces, the patent inverts the approach by using electroplating to deposit copper only where needed rather than etching away material. This additive approach maintains precise line widths and spaces without undercut, enabling high component density while preserving wiring pattern precision
Solution Approach 2:
The patent replaces the mechanical/chemical etching process with electrochemical deposition. By using electroplating controlled by photoresist patterns, the method achieves superior precision for narrow features compared to etching, as the deposition process follows the resist pattern boundaries more accurately without lateral erosion
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
This method enables the creation of circuit boards with fine wiring patterns and reduced material waste, while minimizing environmental impact by recycling silver particles and avoiding the need for copper etching, thus improving component density and reducing pollution.
Implementation Method 1
a first photosensitive resin layer is formed on the base layer; the first photosensitive resin layer is exposed and developed to form a first conductive block
Implementation Method 2
a first electroplated copper wiring is formed on the first conductive block
Data Source
AI summary
A method for manufacturing a circuit board with narrow conductive traces and narrow spaces between traces includes a base layer and two first wiring layers disposed on opposite surfaces of the base layer. Each first wiring layer includes a first bottom wiring and a first electroplated copper wiring. The first bottom wiring is formed on the base layer. The first bottom wiring includes a first end facing the base layer, a second end opposite to the first end, and a first sidewall connecting the first end and the second end. The first electroplated copper wiring covers the second end and the first sidewall of the first bottom wiring.