Photosensitive Polyimide Chain Extenders for Crack-Free Bending
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Solution Overview
Problem
Conventional photosensitive polymer materials used in electronic circuits fail to balance molecular weight requirements for initial manufacturing steps and subsequent forming processes, leading to polymer layer cracks and breaks during bending, rendering devices unusable.
Innovation Solution
A photosensitive polyimide formulation with a latent chain extender is developed, allowing for controlled molecular weight increase from low to high after curing, using a poly(amic acid) salt and a tertiary amine salt of a tetracarboxylic acid to enhance elongation and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight photosensitive polymers are used, then elongation and formability are improved, but viscosity increases and photolithographic processing becomes difficult
Solution Approach 1:
The patent segments the polymer processing into two distinct stages: (1) initial photolithographic processing using low molecular weight polymer for ease of handling and processing, and (2) subsequent forming operations using high molecular weight polymer for elongation. The chain extender enables this segmentation by allowing molecular weight increase after curing, so each stage can use the optimal molecular weight for its specific requirement.
Solution Approach 2:
The patent applies preliminary action by performing the photolithographic processing at low molecular weight before the chain extension occurs. The low molecular weight polymer is processed first through photolithography, then the chain extender increases the molecular weight to achieve the desired elongation for forming operations. This preliminary processing at optimized conditions resolves the contradiction between processability and elongation.
2Ease of manufacture
If low molecular weight polymer formulations are used, then photolithographic processing is easier, but cracks occur during forming operations
Solution Approach 1:
The patent applies dynamics by making the polymer molecular weight changeable over time. The polymer starts at low molecular weight for easy photolithographic processing, then the chain extender activates to increase molecular weight to high levels for crack-free forming operations. This dynamic molecular weight adjustment allows the material to adapt its properties to match the requirements of each processing stage, ensuring both ease of manufacture and reliability.
Solution Approach 2:
The patent changes the molecular weight parameter of the polymer through the chain extender mechanism. The molecular weight increases from low (suitable for photolithography) to high (suitable for forming operations with crack prevention). This parameter change is controlled and timed to occur after photolithography but before or during forming operations, resolving the contradiction between ease of manufacture and polymer layer integrity.
3Strength
If high molecular weight polymer is used, then elongation improves, but filtration time and cost increase
Solution Approach 1:
The patent segments the molecular weight development into two phases: initial low molecular weight polymer for rapid filtration and processing, followed by chain extension to high molecular weight for elongation. This segmentation allows filtration to occur at the low molecular weight stage where it is fast and efficient, then the chain extender increases molecular weight afterward to achieve the desired elongation without incurring filtration time penalties.
Solution Approach 2:
The patent performs filtration and initial processing at low molecular weight before the chain extension occurs. This preliminary action at optimized low molecular weight conditions enables rapid filtration, then the chain extender increases molecular weight to achieve high elongation. By performing filtration beforehand at the optimal molecular weight, the patent avoids the time loss that would occur if filtration were attempted at high molecular weight.
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 formulation achieves improved polymer elongation and formability, preventing cracks and ensuring device integrity during bending by maintaining low viscosity and processability during initial steps and high elongation during forming.
Implementation Method 1
a photosensitive polyimide formulation with a latent chain extender is developed, allowing for controlled molecular weight increase from low to high after curing
Implementation Method 2
using a poly(amic acid) salt and a tertiary amine salt of a tetracarboxylic acid to enhance elongation and formability
Data Source
AI summary
Photosensitive polymer formulations, materials and uses of such materials are disclosed. Embodiments of the present disclosure provide photosensitive polyimide materials having chain extenders and formulations thereof that improve elongation and formability of the polyimide materials, and methods of making such polymer materials.