Condensation-Curable Silicone Gel for Fast, Contamination-Resistant Curing
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Solution Overview
Problem
Existing silicone gels used in electronics are expensive, require elevated curing temperatures, and are susceptible to contamination by platinum-based catalyst poisons, leading to incomplete curing and reversion at high temperatures.
Innovation Solution
A condensation curable gel composition using titanate/zirconate or tin (II) catalysts that can cure in the absence of moisture, allowing for room temperature curing and resistance to contaminants, comprising a silyl terminated polymer, cross-linker, and condensation catalyst in a two-part system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If addition cure chemistry with platinum catalyst is used, then curing speed is improved, but cost increases and susceptibility to contamination worsens
Solution Approach 1:
The patent changes the chemical parameters of the curing system by replacing platinum catalyst with alternative catalysts (tin-based catalysts like dibutyl tin dilaurate or zinc-based catalysts like zinc octoate) and modifying the functional groups from hydrosilylation to condensation chemistry. This parameter change maintains curing functionality while eliminating platinum contamination risks and reducing cost.
2Strength
If addition cure chemistry is used, then adhesion is improved, but cost increases
Solution Approach 1:
The patent replaces expensive platinum catalyst with cheaper alternative catalysts (tin or zinc-based catalysts) that perform the same curing function. This substitution maintains the adhesive properties of the cured gel while significantly reducing material cost, making the encapsulant economically viable for mass production.
3Productivity
If titanate catalyst is used in presence of moisture, then curing is accelerated, but catalytic efficiency is lost due to hydrolysis
Solution Approach 1:
The patent changes the chemical environment parameters by formulating a two-part system that separates moisture-sensitive catalyst from moisture sources. The catalyst is protected from hydrolysis by controlling its exposure to moisture until the curing stage, maintaining both catalytic activity and stability throughout the product lifecycle.
4Quantity of substance
If condensation cure system is used, then cost is reduced, but curing time increases significantly
Solution Approach 1:
The patent optimizes the condensation cure parameters by selecting specific catalyst types and concentrations, controlling humidity levels, and adjusting the ratio of hydroxyl-functional polymer to crosslinker. These parameter optimizations accelerate the condensation reaction rate, reducing curing time from days to hours while maintaining cost advantages over addition cure systems.
5Productivity
If tin cured condensation system is used, then curing time is reduced, but reversion occurs at temperatures above 80°C
Solution Approach 1:
The patent modifies the chemical composition parameters by selecting specific polymer structures, crosslinker types, and catalyst formulations that enhance the thermal stability of the cured network. The optimized condensation cure system achieves both rapid curing and high-temperature stability by balancing reaction kinetics with network structure stability.
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 composition cures quickly, maintains adhesion to substrates, and is resistant to contaminants, providing effective stress relief and protection for electronic components.
Implementation Method 1
a condensation catalyst selected from the group of titanates or zirconates... The composition cures quickly... providing effective stress relief and protection for electronic components
Implementation Method 2
condensation curable gel composition... cured via a condensation cure chemistry... reaction of a silicon hydride group with onto an unsaturated carbon radical
Implementation Method 3
at least one condensation curable silyl terminated polymer having at least one, typically at least 2 hydrolysable and/or hydroxyl functional groups per molecule
Data Source
AI summary
There is provided a gel which is the condensation reaction product of the following composition: (i) at least one condensation curable silyl terminated polymer having at least one, typically at least 2 hydrolysable and/or hydroxyl functional groups per molecule; (ii) a cross-linker selected from the group of a silicone, an organic polymer, a silane or a disilane molecule which contains at least two hydrolysable groups per molecule and typically at least three hydrolysable groups per molecule and (iii) a condensation catalyst selected from the group of titanates, zirconates or tin (II) characterized in that the molar ratio of hydroxyl and/or hydrolysable groups in polymer (i) to hydrolysable groups from (ii) is between 0.5: 1 and 1:1 using a monosilane cross linker or 0.75:1 to 3: 1 using disilanes and the molar ratio of M-OR or tin II functions to the hydroxyl and/or hydrolysable groups in polymer (i) is comprised between 0.01:1 and 0.5:1, where M is titanium or zirconium. The composition, and uses for the gel are also described.