Epoxy-Modified Photosensitive Polyimide for Low-Temperature Curing
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Solution Overview
Problem
Conventional photosensitive polyimides require high-temperature hard baking, which can lead to oxidation of copper circuits and adverse effects on electrical properties and reliability, especially when thicker films or coverlay films are needed, and they are not suitable for applications requiring flexibility and heat resistance.
Innovation Solution
A photosensitive polyimide with a specific structure that is curable at low temperatures, allowing for the formation of thick films with improved reactivity, stability, and heat resistance, achieved by modifying polyimides with an epoxy compound containing a photosensitive group, such as a C═C double bond, enabling radiation curing without high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photosensitive polyimides are used and high-temperature hard baking is applied, then the polyimide film can be cured and formed, but the copper circuits are oxidized and electrical properties deteriorate
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by introducing carboxyl groups at specific positions in the molecular chain, enabling the material to cure at lower temperatures (below 300°C) while maintaining film-forming capabilities. This structural modification allows the polyimide to achieve proper curing without subjecting copper circuits to oxidizing high-temperature conditions.
Solution Approach 2:
The patent creates a composite polyimide structure combining aromatic polyimide backbone with pendant carboxyl groups, achieving a material that exhibits both low-temperature curability and high-temperature resistance. The composite structure integrates the thermal stability of polyimide with the reactive functionality of carboxyl groups, enabling curing at lower temperatures while maintaining reliability.
2Length of stationary object
If conventional photosensitive polyimides are used, then the polyimide can be formed, but thicker films cannot be effectively produced
Solution Approach 1:
The patent modifies the molecular parameters of the polyimide by incorporating carboxyl groups that enable better crosslinking density and network formation. This allows the material to form uniform thick films through low-temperature curing processes, achieving both increased film thickness and maintained film formation capability.
3Stability of the object's composition
If high-temperature hard baking is applied to cure photosensitive polyimide, then the polyimide achieves proper curing, but copper circuits are oxidized
Solution Approach 1:
The patent changes the curing temperature parameter from high-temperature (above 300°C) to low-temperature (below 300°C) processing by modifying the polyimide structure with carboxyl groups. This enables complete curing and stable composition formation without exposing copper circuits to oxidizing high-temperature environments.
Solution Approach 2:
The patent replaces thermal curing mechanism with a photo-curing mechanism initiated by UV irradiation. The carboxyl-containing polyimide structure enables photodecarboxylation reactions that proceed at lower temperatures, substituting the high-temperature thermal curing process with a lower-temperature photochemical process that protects copper circuits from oxidation.
4Reliability
If conventional polyimide structures are used, then the material provides basic protection, but heat resistance and chemical resistance are insufficient
Solution Approach 1:
The patent creates a composite polyimide structure combining the thermally stable aromatic polyimide backbone with functional carboxyl groups. This composite structure provides enhanced heat resistance and chemical resistance while maintaining processability. The carboxyl groups participate in crosslinking to form a dense three-dimensional network that improves thermal and chemical stability.
Solution Approach 2:
The patent introduces carboxyl groups at specific local positions (pendant groups) on the polyimide molecular chain rather than throughout the entire structure. This localized modification provides the necessary reactivity for low-temperature curing and enhanced resistance properties without excessively complicating the overall molecular structure.
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 provides a photosensitive composition with excellent electrical properties, heat resistance, flexibility, and chemical resistance, suitable for use in solder resist, coverlay, and printed wiring boards, preventing copper circuit oxidation and enhancing product reliability.
Implementation Method 1
modifying polyimides with an epoxy compound containing a photosensitive group, such as a C═C double bond, enabling radiation curing without high-temperature processing
Data Source
AI summary
The invention pertains to an epoxy-modified photosensitive polyimide, which possesses excellent heat resistance, chemistry resistance, and flexibility, and can be used in a liquid photo resist or dry film resist, or used in a solder resist, coverlay film, or printed circuit board.