Isocyanate-Modified Photosensitive Polyimide for Flexible PCBs
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Solution Overview
Problem
Existing photosensitive polyimides face challenges with storage-stability and heat-stability, particularly due to the generation of OH functional groups after ring-opening reactions, which affect their performance in electronic components requiring flexibility and heat resistance.
Innovation Solution
An isocyanate-modified photosensitive polyimide is developed, featuring a specific chemical structure that allows for excellent stability and low-temperature curing, incorporating a photosensitive group to enhance electrical, heat, and chemical resistance properties, suitable for use in solder resist, coverlay films, and printed circuit boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy-modified photosensitive polyimide is prepared by reacting epoxide with acid, then photosensitivity is achieved, but storage-stability and heat-stability deteriorate due to OH functional groups generated after ring-opening reaction
Solution Approach 1:
The patent changes the chemical modification approach from epoxy-based to isocyanate-based modification. This parameter change in the chemical structure eliminates the formation of problematic OH functional groups while maintaining photosensitivity, thereby resolving the contradiction between achieving photosensitivity and maintaining storage-stability and heat-stability.
Solution Approach 2:
The patent introduces isocyanate groups as an intermediary modification approach. Instead of using epoxy groups that generate harmful OH groups, isocyanate groups serve as a mediating chemical structure that provides photosensitivity without compromising the stability of the polyimide composition.
2Temperature
If conventional photosensitive polyimide is used, then heat resistance is maintained, but curing temperature requires high energy input
Solution Approach 1:
The patent modifies the chemical structure by introducing isocyanate groups that enable low-temperature curing. This parameter change in the chemical composition allows the material to maintain heat resistance while reducing the curing temperature from conventional high temperatures to below 100°C, thereby resolving the contradiction between heat resistance and curing energy input.
3Stability of the object's composition
If non-polyimide based coverlay film is used, then flexibility is improved, but heat resistance deteriorates
Solution Approach 1:
The patent creates a composite material system by modifying polyimide with isocyanate groups and incorporating photosensitive components. This composite approach maintains the inherent heat resistance of polyimide while adding flexibility and photosensitivity through the modification, thereby resolving the contradiction between flexibility and heat resistance.
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 isocyanate-modified photosensitive polyimide achieves improved stability, flexibility, and resistance to heat and chemicals, making it suitable for advanced electronic components with enhanced performance in flexible printed wiring boards and other applications.
Implementation Method 1
An isocyanate-modified photosensitive polyimide is developed, featuring a specific chemical structure that allows for excellent stability and low-temperature curing, incorporating a photosensitive group to enhance electrical, heat, and chemical resistance properties
Data Source
AI summary
The invention pertains to an isocyanate-modified photosensitive polyimide. The photosensitive polyimide of the invention possesses excellent heat resistance, chemical resistance and flexibility, and can be used in a liquid photo resist composition or dry film photo resist composition, or used in a solder resist, coverlay film, or printed wiring board.