Photosensitive Polyimide Resin for Circuit Substrate Dimensional Stability
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Solution Overview
Problem
Conventional photosensitive polyimide resins used in circuit formation substrates for hard disk drives face issues such as high water absorbability leading to dimensional variations, low solubility in organic solvents, and difficulties in achieving differential solubility between exposed and unexposed areas, which affect pattern formation accuracy and device performance.
Innovation Solution
A photosensitive resin composition comprising a polymer with structural units containing carbon-carbon unsaturated double bonds and a sensitizer that generates radicals upon irradiation, allowing for improved sensitivity, resolution, and reduced hygroscopic expansion, enabling the formation of precise patterns as interlayer insulating or protective films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyimide resin layer with high water absorbability is used to improve heat resistance and mechanical properties, then the protective and insulating functions are enhanced, but the substrate dimensions vary largely due to water adsorption and desorption, causing warping and alignment accuracy degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the polyimide resin by introducing specific structural units (formula 1) with controlled substituent groups (R1-R8) that modify the resin's hygroscopic properties. By selecting specific diamine and dicarboxylic acid components, the resin achieves lower water absorbability while maintaining heat resistance and mechanical strength, thereby preventing substrate warping and preserving alignment accuracy during manufacturing.
2Manufacturing precision
If a polyimide resin with low water absorption is used to reduce dimensional variation, then alignment accuracy is improved, but the resin contains fluorine and has a rigid structure that significantly reduces solubility in organic solvents, making pattern formation difficult
Solution Approach 1:
The patent applies local quality by introducing specific functional groups at particular positions (R1-R8) in the polyimide molecular structure. The resin contains low-water-absorption structural units with specific substituent configurations that provide controlled solubility characteristics. This localized structural modification enables the resin to maintain low hygroscopic expansion while achieving adequate solubility in organic solvents for pattern formation, resolving the contradiction between dimensional stability and manufacturability.
3Productivity
If conventional photosensitive polyimide is used to simplify pattern formation steps, then production time is reduced, but the resin exhibits high water absorbability that causes substrate warping and performance deterioration
Solution Approach 1:
The patent creates a composite polyimide resin structure combining low-water-absorption structural units (formula 1) with photosensitive functional groups. This composite molecular architecture integrates the benefits of both low hygroscopic expansion (for device performance) and photosensitivity (for simplified pattern formation and reduced production time). The specific diamine-dicarboxylic acid combination provides both dimensional stability and photo-reactivity, eliminating the need to choose between productivity and reliability.
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 resin composition enhances pattern formation sensitivity and resolution, reduces production time, and improves workability, resulting in a high-reliability circuit formation substrate with excellent interlayer insulating or protective layer properties.
Implementation Method 1
a compound (b) which generates a radical when irradiated with active rays
Data Source
AI summary
A photosensitive resin composition for an interlayer insulating film or a protective film of a substrate for circuit formation, which includes a polymer (a) having a structural unit shown by the formula (A) and a compound (b) which generates a radical when irradiated with active rays and has a structure shown by the following formula (B).