Resin Composition for High-Density PCBs Using Vinylene Carbonate Photoinitiator
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Solution Overview
Problem
Existing resin compositions for multilayer printed wiring boards face challenges due to poor light transmissivity of bismaleimide compounds, which hinders photocuring reactions and results in inadequate alkaline developability, limiting their use in high-density printed wiring boards.
Innovation Solution
A compound with a specific carboxyl group is used in the exposure and development steps, allowing for suitable curing without inhibiting photocuring reactions and imparting excellent alkaline developability to the resin composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bismaleimide compound is used as a curable resin, then the resin composition can be cured, but light transmissivity becomes poor, preventing sufficient light from reaching the photo initiator
Solution Approach 1:
The patent uses a composite resin composition containing both bismaleimide compound (for curing reliability) and vinylene carbonate (for improved light transmissivity and photocuring). This composite approach allows the system to benefit from both materials: the bismaleimide provides thermal stability and cure strength, while vinylene carbonate enhances light penetration and acts as a photoinitiator, resolving the contradiction between curing reliability and light transmissivity.
Solution Approach 2:
Vinylene carbonate serves as an intermediary substance that bridges the gap between light and the bismaleimide compound. It absorbs light effectively and generates radicals that initiate the curing of bismaleimide, allowing the system to achieve both good light transmissivity and reliable curing without requiring the bismaleimide itself to be transparent to light.
2Reliability
If a bismaleimide compound is used as a curable resin, then the resin can be cured, but alkaline-developability becomes insufficient, leaving unexposed resin after development
Solution Approach 1:
The patent creates a composite system where vinylene carbonate complements the bismaleimide compound by providing alkaline-developability. The vinylene carbonate-based cured product has different chemical properties than bismaleimide, allowing selective removal of unexposed areas with alkaline developers while preserving the exposed, crosslinked structure, thus enabling both reliable curing and good developability.
Solution Approach 2:
The resin composition exhibits different properties in exposed versus unexposed regions. In exposed areas, the resin is fully crosslinked and resistant to alkaline development. In unexposed areas, the resin remains partially soluble in alkaline developers. This local differentiation of properties enables successful photolithography patterns while maintaining overall curing reliability.
3Reliability
If additional heating is performed before development to cure the maleimide compound, then curing is achieved, but heating prevents obtaining highly detailed resist patterns
Solution Approach 1:
The patent replaces thermal curing (heating) with photocuring (light irradiation). By using vinylene carbonate as a photoinitiator that generates radicals upon light exposure, the system achieves curing through photochemical reactions instead of thermal processes. This substitution eliminates the need for heating steps, allowing direct formation of high-resolution patterns without thermal distortion or loss of pattern detail.
Solution Approach 2:
The patent changes the curing mechanism from thermal activation to photochemical activation. By selecting a photoinitiator (vinylene carbonate) that responds to light wavelengths suitable for high-resolution direct imaging, the system achieves curing at lower temperatures and with better spatial control, thereby improving pattern detail accuracy while maintaining curing 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 use of the specific carboxyl group compound enables efficient photocuring and excellent alkaline developability, facilitating the production of high-density multilayer printed wiring boards with improved performance.
Implementation Method 1
a photo radical polymerization initiator (a curing agent)
Implementation Method 2
an exposed portion is cured by irradiation of rays of light
Data Source
AI summary
The compound (A) is represented by formula (1).R1O—R2—OR1 (1)(In formula (1), each R1 independently represents a group represented by formula (2), or a hydrogen atom, and R2 represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms, provided that at least one R1 is a group represented by formula (2).)(In formula (2), -* represents a bonding hand.).