Thinned Flexible Polyimide Substrate with Nanopore Adhesion
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Solution Overview
Problem
Current flexible substrate patterning methods, such as 2-layer and 3-layer FCCL, face challenges in achieving fine lines and small apertures while being environmentally unfriendly and costly, with issues like peeling due to poor adhesion between the conductor layer and substrate, especially with direct patterning methods using metal ink or paste.
Innovation Solution
A thinned flexible polyimide substrate is developed with a conductor layer of stacked metal nanoparticles and a polyimide resin that fills the pores between them, forming a strong insulating layer, allowing for better adhesion and reducing environmental impact through a process involving sintering and imidization of polyamic acid solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct patterning with metal ink is used on polyimide film, then the lithography process is eliminated and environmental pollution is reduced, but the adhesion between conductor layer and substrate is poor resulting in peeling
Solution Approach 1:
The conductor layer is designed with a porous structure containing numerous pores that allow polyimide resin to penetrate and embed into the conductor layer. This creates mechanical interlocking and chemical bonding between the conductor and substrate, significantly improving adhesion and preventing peeling while maintaining the simplicity of direct patterning manufacturing process
Solution Approach 2:
The invention creates a composite structure where metal particles (conductor) are combined with polyimide resin (substrate material) within a porous matrix. This composite approach allows the conductor layer to be both electrically conductive and strongly adhered to the flexible substrate, resolving the adhesion problem while maintaining manufacturing simplicity
2Manufacturing precision
If conventional etching process is used for patterning, then fine lines and small apertures can be produced, but environmental protection requirements are not met and production cost increases
Solution Approach 1:
The invention replaces the conventional chemical etching process with a direct patterning method using metal ink or metal paste that is printed directly onto the polyimide film. This substitution eliminates the need for harmful etching chemicals and their associated environmental pollution while achieving fine line and small aperture patterns through controlled deposition and sintering processes
Solution Approach 2:
The invention changes the patterning approach from removing material (etching) to depositing and sintering metal particles directly. By controlling parameters such as particle size, deposition density, and sintering conditions, fine line and small aperture patterns are achieved without environmental harm, maintaining manufacturing precision while eliminating pollution
3Reliability
If sputtering method is used to form copper foil substrate, then mature technology and good performance are achieved, but huge equipment investment is required including vacuum sputtering equipment and electroplating equipment
Solution Approach 1:
The invention replaces expensive vacuum sputtering equipment and electroplating equipment with simpler, more affordable direct printing and sintering technology. By using commercially available metal inks or pastes that can be applied through conventional printing methods, the need for costly vacuum chambers and complex equipment is eliminated, significantly reducing equipment investment while maintaining conductor layer performance
Solution Approach 2:
The metal particles in the ink or paste self-organize and form conductive pathways when sintered, eliminating the need for complex vacuum deposition processes. The material itself performs the function of creating the conductor layer through simple heating, reducing equipment complexity and investment requirements while achieving reliable conductor performance
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 achieves strong adhesion between the conductor and insulating layers, preventing peeling and enhancing the substrate's heat resistance and conductivity, while reducing environmental pollution and production costs.
Implementation Method 1
a conductor layer formed of a plurality of stacked metal nanoparticles having pores therebetween
Implementation Method 2
A portion of the polyimide resin fills into the pores
Implementation Method 3
the polyimide insulating layer is formed of the polyimide resin coated on the conductor layer
Implementation Method 4
the patterned circuit is then sintered to form a continuous dense wire
Data Source
AI summary
The present invention provides a thinned flexible polyimide substrate and a method for manufacturing the same. The thinned flexible polyimide substrate comprises a polyimide resin, a conductor layer, and a polyimide insulating layer. The polyimide resin has a linear thermal expansion coefficient of less than 40 ppm/K. The conductor layer is formed of a plurality of stacked metal nanoparticles having pores therebetween, and each of the pores has a size between 0.1 μm and 1 μm. A portion of the polyimide resin fills into the pores. The polyimide insulating layer is formed of the polyimide resin coated on the conductor layer.