Onium Salt Composition for Corrosion-Resistant Cationic Polymerization

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional photo-cationically polymerizable epoxy resin compositions used in electronic components face issues with fluorine ion generation causing corrosion, limited productivity, poor cold rapid curing properties, and storage stability when used with sulfonium-borate complexes as thermal cationic polymerization initiators.

Innovation Solution

An onium salt with a specific structure, represented by general formulas (1) and (2), is used in a composition that includes a cationically polymerizable compound, a filler, and a solvent, to enhance migration resistance, reduce fluorine ion generation, improve curing properties, and ensure storage stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If sulfonium-antimonate complexes are used as photo-cationic polymerization initiators, then polymerization can be initiated by light, but large amounts of fluorine ions are generated causing migration between dissimilar metals and corrosion

Engineering Contradiction:

Improvepolymerization initiation capabilityVSAvoidfluorine ion generation and corrosion

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful fluorine-containing counter anion (SbF6-) from the sulfonium salt structure and replaces it with a non-fluorine-containing counter anion such as borate (BF4-), phosphate (PF6-), or sulfonate (CF3SO3-). This extraction eliminates the source of fluorine ion generation while preserving the cationic polymerization initiation function of the sulfonium cation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical composition parameter of the counter anion from fluorine-containing (SbF6-) to non-fluorine-containing (BF4-, PF6-, CF3SO3-). This parameter change fundamentally alters the chemical behavior during polymerization, preventing fluorine ion migration and corrosion while maintaining the electrophilic catalysis needed for cationic polymerization.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If sulfonium-borate complexes are used as thermal cationic polymerization initiators, then productivity may be improved, but cold rapid curing properties and storage stability deteriorate

Engineering Contradiction:

Improvecuring speedVSAvoidstorage stability and cold curing properties

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a composite initiator system by combining sulfonium salts with specific counter anions (borate, phosphate, or sulfonate) in defined molar ratios. This composite structure allows the sulfonium cation to provide thermal cationic polymerization initiation capability while the specific counter anion maintains storage stability and enables cold rapid curing, achieving synergistic effects that satisfy multiple contradictory requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent assigns different functional roles to different components of the sulfonium salt: the sulfonium cation (R3S+) provides the electrophilic center for cationic polymerization initiation, while the counter anion (BF4-, PF6-, or CF3SO3-) provides thermal stability and influences curing characteristics. This local functional differentiation allows each component to optimize its specific function, resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #3Local quality

3Reliability

If more curing agent is used to improve cold rapid curing properties, then storage stability may improve, but the amount of curing agent increases reducing productivity

Engineering Contradiction:

Improvestorage stabilityVSAvoidcuring efficiency per unit amount

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical structure parameters of the counter anion from conventional options to specifically designed borate, phosphate, or sulfonate anions with optimized electronic and steric properties. This parameter change increases the thermal stability and reactivity of the initiator, enabling effective curing at lower concentrations and temperatures, thereby improving storage stability without requiring excessive amounts of curing agent.

Inventive Principle:

Principle #35Parameter changes

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 onium salt composition achieves well-balanced physical properties including excellent cold curing, thermal shock resistance, and moisture resistance, while minimizing the amount of curing agent used and improving productivity.

Implementation Method 1

If sulfonium-borate complexes can be diverted to thermal cationic polymerization initiators for thermally cationically polymerizable epoxy resin compositions

Methodology Applied

Scientific EffectThermal cationic polymerization: Photopolymerisation

Data Source

PatentUS10189781B2Onium salt and composition comprising the same

Publication Date: 2019.01.29 ASAHI KASEI E-MATERIALS CORPORATION

AI summary

The onium salt of the present invention contains predetermined compound A represented by the general formula (1). The composition of the present invention contains the onium salt of the present invention, and an onium salt containing predetermined compound B represented by the general formula (2). The onium salt and the composition of the present invention exert well-balanced excellent physical properties in terms of cold curing properties, storage stability, thermal shock resistance after curing, and moisture resistance.