Photosensitive Resin Composition for High-Resolution Resist Patterns
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Solution Overview
Problem
Conventional photosensitive resin compositions for printed wiring boards face challenges in achieving a balance between resolution, adhesiveness, flexibility, and developability, particularly in forming resist patterns with line widths and spaces of 10/10 μm or less, while also requiring reduced exposure time and improved production efficiency.
Innovation Solution
A photosensitive resin composition combining a binder polymer with structural units derived from (meth)acrylic acid, styrene or α-methylstyrene, and hydroxyalkyl (meth)acrylate ester, along with a photopolymerizable compound containing ethyleneoxy and propyleneoxy groups, and a photopolymerization initiator, which enhances the formation of resist patterns with improved resolution, adhesiveness, flexibility, and developability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the crosslink density is increased to improve resolution, then the resolution is improved, but the resist pattern becomes hard and fragile, causing cracking
Solution Approach 1:
The patent changes the chemical composition parameters of the photosensitive resin by incorporating specific flexible chain structures (polyethylene glycol and polypropylene glycol units) and controlling the ratio of rigid aromatic rings to flexible aliphatic chains. This parameter optimization allows achieving high resolution through increased crosslink density while maintaining flexibility through the embedded flexible segments, thus resolving the contradiction between resolution and flexibility.
Solution Approach 2:
The patent creates a composite molecular structure within the photosensitive resin by combining rigid aromatic ring units (providing resolution) with flexible polyethylene glycol and polypropylene glycol chain units (providing flexibility). This composite approach at the molecular level allows the resist pattern to simultaneously achieve high resolution and flexibility, preventing cracking while maintaining fine pattern definition.
2Manufacturing precision
If a direct writing exposure method is used to improve alignment accuracy and pattern fineness, then the alignment accuracy and pattern fineness are improved, but the exposure time increases
Solution Approach 1:
The patent modifies the photosensitive resin composition to include specific photopolymerizable compounds with high photoreactivity and appropriate molecular weights, along with optimized photopolymerization initiators. These parameter changes increase the sensitivity of the photosensitive resin, allowing the direct writing exposure method to achieve the required crosslinking density in shorter exposure times, thus reducing the time penalty while maintaining the alignment accuracy and pattern fineness benefits.
3Strength
If the flexibility of the resist pattern is increased to prevent cracking, then the flexibility is improved, but the resolution property is reduced
Solution Approach 1:
The patent optimizes the molecular weight and ratio of flexible chain units (polyethylene glycol and polypropylene glycol) to achieve the minimum flexibility required to prevent cracking without excessive softness that would compromise resolution. By precisely controlling these parameters, the resist pattern achieves just enough flexibility to be crack-resistant while maintaining sufficient rigidity for high-resolution patterning.
Solution Approach 2:
The patent employs a composite molecular architecture where rigid aromatic ring units provide the structural framework for high resolution, while dispersed flexible polyethylene glycol and polypropylene glycol units provide localized flexibility to prevent cracking. This composite structure allows the resist to simultaneously exhibit high resolution and adequate flexibility by distributing these opposing properties at different molecular locations.
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 proposed composition enables the efficient formation of resist patterns with excellent resolution, adhesiveness, and flexibility, suitable for high-density package substrates, while reducing exposure time and improving production efficiency in the manufacturing of printed wiring boards.
Implementation Method 1
irradiated with active light rays to cure the exposed area
Data Source
AI summary
A photosensitive resin composition includes a binder polymer, a photopolymerizable compound, and a photopolymerization initiator. The binder polymer has a structural unit derived from a (meth)acrylic acid, a structural unit derived from styrene or α-methylstyrene, and a structural unit derived from a hydroxyalkyl (meth)acrylate ester having a hydroxyalkyl group having from 1 to 12 carbon atoms. The photopolymerizable compound include a bisphenolic di(meth)acrylate having from 1 to 20 structural units of an ethyleneoxy group and having from 0 to 7 structural units of a propyleneoxy group.