PCB Copper Particle Bond Layer for Optical Inspection Contrast
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Solution Overview
Problem
Existing printed circuit boards face challenges in achieving sufficient contrast between circuit surfaces and base film surfaces, leading to increased inspection error rates for circuit defects during automated optical inspections.
Innovation Solution
A printed circuit board with a copper particle bond layer on an insulating base film, where the lightness of the non-formed region is 60 or less, enhancing the contrast between the conductive pattern and non-formed regions, and optionally incorporating a modified layer to adjust lightness and chromaticity, thereby improving defect detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional metal plating layer is formed by sputtering and electroplating, then the conductive pattern can be created, but the contrast between the circuit surface and base film surface is insufficient for automated optical inspection
Solution Approach 1:
The patent applies color/lightness change by forming a copper particle bond layer that creates a dark, reflective surface on the conductive pattern. The copper particles are bonded to the base film to form a conductive pattern with low lightness (high darkness), creating sufficient contrast against the lighter base film surface for automated optical inspection systems to accurately detect circuit defects.
Solution Approach 2:
The patent changes the physical and optical parameters of the conductive pattern by using copper particles with specific size distributions (0.1-10 μm) and controlling their bonding density. This creates a surface with specific light reflection characteristics that enhance contrast for optical inspection, while maintaining electrical conductivity.
2Illumination intensity
If the base film lightness is increased to improve visibility, then the contrast with conductive patterns improves, but the inspection error rate increases due to insufficient differentiation
Solution Approach 1:
Instead of changing the base film lightness, the patent changes the color/lightness of the conductive pattern surface by forming a copper particle bond layer. This creates a dark, reflective surface that provides high contrast against the base film, enabling accurate defect detection without altering base film properties.
3Measurement precision
If a copper particle bond layer is formed to enhance contrast, then inspection accuracy improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent extracts the essential function of creating a dark, reflective conductive surface from the conventional multi-step sputtering and electroplating process. By using only the copper particle bonding step, it eliminates unnecessary intermediate layers and complex plating procedures while achieving the desired optical contrast for inspection.
Solution Approach 2:
The patent uses a simple copper particle bonding process instead of expensive, multi-step metal plating. The copper particles serve as a disposable, functional layer that provides both electrical conductivity and optical contrast, replacing complex, costly manufacturing steps.
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 enhanced contrast reduces inspection error rates and the occurrence of circuit defects, while maintaining the material properties of the base film, ensuring high accuracy in defect detection and reliability of the printed circuit board.
Implementation Method 1
the presence or absence of circuit defects is determined on the basis of the contrast of reflected light
Data Source
AI summary
A printed circuit board according to an embodiment of the present invention includes a base film having an insulating property and a conductive pattern disposed on at least one surface of the base film. The conductive pattern includes a copper particle bond layer which is fixed to the base film, and a lightness L* of a conductive pattern non-formed region of the base film is 60 or less. The base film may include a modified layer on one surface side thereof.