Flexible Substrate Via Filling for Precise Double-Sided Interconnects
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Solution Overview
Problem
Conventional methods for forming via holes in flexible substrates are complex and inefficient, leading to increased manufacturing difficulty and cost, particularly when double-sided patterned interconnection is required.
Innovation Solution
A method involving the formation of a seed metal layer on a base substrate, patterning it to create a conductive pattern, and then forming a flexible substrate with a via hole through dry etching, followed by electroplating to fill the hole and removing the substrate using laser ablation, allowing direct formation of additional metal layers without substrate transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional laser cutting technology is used to form micro-holes in polyimide substrates, then the manufacturing process is simple, but the manufacturing precision is low and burrs are formed on the edges
Solution Approach 1:
The patent combines multiple functions into the flexible substrate itself: the substrate serves as both the structural base and the etching mask. By forming the mask pattern directly on the flexible substrate through photoresist coating and patterning, the patent eliminates the need for separate mask preparation and substrate transfer steps, achieving both manufacturing simplicity and high precision micro-hole formation without edge burrs through controlled dry etching
Solution Approach 2:
The patent performs preliminary patterning of the flexible substrate to create mask regions before the dry etching process. The photoresist is coated and patterned in advance to define the mask areas that will protect certain regions during etching, ensuring precise micro-hole formation with clean edges while maintaining process simplicity
2Manufacturing precision
If dry etching process is used to form via holes in flexible substrate, then manufacturing precision is improved, but the process complexity increases due to substrate transfer requirements
Solution Approach 1:
The patent merges the mask function directly into the flexible substrate by forming photoresist patterns on the substrate itself. This integration eliminates the need for separate mask substrates and transfer operations, maintaining high via hole formation precision through dry etching while significantly reducing process complexity
Solution Approach 2:
The patent extracts the mask function from a separate component and integrates it directly into the flexible substrate structure. By forming the mask pattern in-situ on the flexible substrate through photoresist coating and patterning, the patent removes the complex substrate transfer step while preserving the precision benefits of dry etching
3Manufacturing precision
If special photosensitive liquid polyimide is used to form micro-holes, then manufacturing precision is improved to about 10 μm, but the manufacturing cost is greatly increased
Solution Approach 1:
The patent changes the material parameter from special photosensitive liquid polyimide to conventional polyimide film with photoresist coating. This parameter change maintains the manufacturing precision of about 10 μm through controlled dry etching with photoresist masks while dramatically reducing material costs and making the process more economically viable
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
Simplifies the manufacturing process by reducing the number of steps and improving electrical connection and packaging sealability, enabling double-sided interconnection and facilitating applications such as bezel-free displays and multi-layer circuitry.
Implementation Method 1
removing the de-bonding layer through laser
Implementation Method 2
filling the first via hole with a conductive metal through an electroplating process
Implementation Method 3
forming a first via hole in the flexible substrate though a dry etching process
Data Source
AI summary
The present disclosure provides a method for forming a via hole in a flexible substrate, including: providing a base substrate and forming a de-bonding layer on the base substrate; forming a seed metal layer on the de-bonding layer, and patterning the seed metal layer to form a first conductive pattern; forming a first flexible substrate on the seed metal layer; forming a first mask layer on the first flexible substrate; and forming a first via hole in the flexible substrate though a dry etching process, the first via hole penetrating the first flexible substrate to expose a connection region of the first conductive pattern. The present disclosure further provides a method for filling a via hole in a flexible substrate.