Flexible Transparent PCB Using PEN Film and Screen Printed Ink
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing printed circuit boards (PCBs) with transparent substrates and covering layers face challenges in manufacturing, particularly in creating a flexible and optically clear structure that maintains mechanical properties and avoids wrinkling during the formation of a conductive wiring pattern and protective layer.
Innovation Solution
A method involving a substrate with a polyethylene naphthalate (PEN) base layer, a transparent adhesive layer, and a copper conductive layer with blackening layers, where the conductive layer is patterned using an image transfer and etching process, and a protective ink layer composed of cycloaliphatic epoxy resin, phenoxyl resin, and methylhexahydrophthalic anhydride is applied via screen printing to form a flexible and transparent PCB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent substrate and covering layer are used to make the circuit visible, then optical clarity is improved, but mechanical stability deteriorates causing wrinkling during manufacturing
Solution Approach 1:
The patent uses a flexible transparent substrate made of polyethylene naphthalate (PEN) film instead of rigid glass or plastic. This thin film substrate maintains optical clarity while providing the flexibility needed to prevent wrinkling during the manufacturing process, particularly during screen printing of the protective layer.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers: a PEN base layer, a transparent adhesive layer, a conductive layer with blackening layers, and a protective ink layer. This composite material approach combines the optical properties of transparent materials with the mechanical stability of the multi-layer construction, resolving the contradiction between visibility and structural integrity.
2Ease of manufacture
If screen printing is used to form the protective layer, then manufacturing simplicity is improved, but surface quality deteriorates causing potential wrinkling
Solution Approach 1:
The flexible PEN substrate acts as a tensioned membrane during screen printing, preventing the formation of wrinkles and surface defects. The flexibility of the substrate allows it to conform to the screen printing process while maintaining surface quality, thus enabling simple manufacturing without sacrificing surface precision.
Solution Approach 2:
The patent applies the protective ink layer through screen printing before final assembly and testing. This preliminary application of the protective layer ensures proper adhesion and surface quality while the substrate is still in optimal condition, preventing later manufacturing issues and simplifying the overall process.
3Reliability
If copper conductive layer with blackening layers is used, then electrical conductivity is improved, but optical transparency deteriorates
Solution Approach 1:
The patent applies blackening layers selectively to specific regions of the copper conductive layer where electrical conductivity is required. The blackening is not applied uniformly across the entire substrate, but only in localized areas corresponding to circuit traces and contact pads. This local application maintains electrical conductivity while preserving optical transparency in non-conductive areas, allowing the circuit pattern to remain visible through the transparent substrate.
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 method enables the production of flexible, optically clear PCBs with enhanced mechanical and weather resistance properties, preventing wrinkling and allowing for visible observation of the wiring pattern, while avoiding yellowing and maintaining excellent optical performance.
Implementation Method 1
The first blackening layer 1132 and the second blackening layer 1133 are formed on two opposite surfaces of the conductive metal layer 1131, respectively. The first blackening layer 1132 and the second blackening layer 1133 are formed by blacking the conductive metal layer 1131.
Implementation Method 2
The conductive layer 113 is fixedly connected to the base layer 111 by the adhesive layer 112.
Implementation Method 3
an ink 115 is printed on the wiring pattern 114 to form a protecting layer
Implementation Method 4
the ink 115 includes a cycloaliphatic epoxy resin, a phenoxyl resin solution, a solvent, a hardener, and an antifoaming agent
Data Source
AI summary
A PCB includes a base layer, a wiring pattern formed on a surface of the base layer, and a protecting layer formed on the wiring pattern. The protecting layer is formed by printing and solidifying an ink on the wiring pattern. The ink includes a cycloaliphatic epoxy resin, a phenoxyl resin solution, a solvent, a hardener, and an antifoaming agent.