Addition-Cure Silicone Composition Microcapsule Catalyst
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Solution Overview
Problem
Addition-curable silicone compositions face issues with premature curing and hydrosilylation catalyst deactivation when exposed to high temperatures exceeding 200°C, leading to potential defects in semiconductor devices.
Innovation Solution
Incorporating hydrosilylation catalyst particles with a microcapsule structure, where a platinum family metal complex serves as the core material and a three-dimensional crosslinked polymeric compound acts as the wall material, ensuring slow diffusion and maintained catalytic activity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the addition-curable silicone composition is exposed to high temperatures exceeding 200°C during lead-free solder bonding, then the curing reaction initiates prematurely, but this causes the composition to cure before the proper curing step, leading to device defects
Solution Approach 1:
The catalyst system is segmented into two distinct components: a hydrosilylation catalyst contained within microcapsules and a crosslinking agent in the bulk composition. The microcapsule structure physically separates the catalyst from the reactants until the desired time, preventing premature curing while enabling controlled curing when the microcapsules are broken or opened.
Solution Approach 2:
The microcapsules are pre-loaded with the hydrosilylation catalyst and dispersed in the composition before use. This preliminary preparation allows the catalyst to be protected and isolated during storage and processing, then activated on-demand when the microcapsules are broken, enabling precise timing of the curing reaction.
2Reliability
If the hydrosilylation catalyst is exposed to high temperatures exceeding 200°C, then the catalyst deactivates rapidly, but this results in insufficient curing and loss of device reliability
Solution Approach 1:
The microcapsule shell acts as an intermediary protective barrier between the hydrosilylation catalyst and the high-temperature environment. This shell isolates the temperature-sensitive catalyst from thermal degradation during lead-free solder bonding, allowing the catalyst to remain active and functional when needed for the curing reaction.
Solution Approach 2:
The microcapsule structure changes the thermal environment parameters experienced by the catalyst. By providing thermal insulation and isolation, the microcapsules maintain a lower effective temperature around the catalyst during high-temperature processing, preserving catalyst activity without requiring changes to the catalyst chemistry itself.
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
Prevents premature curing and maintains catalyst activity even at temperatures above 200°C, ensuring proper curing and reliability of semiconductor devices.
Implementation Method 1
a three-dimensional crosslinked polymeric compound obtained by polymerizing at least one type of polyfunctional monomer (C'') serves as a wall material
Implementation Method 2
the rate of diffusion by the hydrosilylation catalyst into the composition is slow
Implementation Method 3
the polymeric compound serving as the wall material buffers the heat transmitted to the hydrosilylation catalyst
Data Source
AI summary
This addition-cure silicone composition comprises (A) an organopolysiloxane that has two or more aliphatic unsaturated hydrocarbon groups per molecule and has a kinematic viscosity of 60-100,000 mm2/s at 25°C, (B) an organohydrogen polysiloxane that has two or more silicon atom-bonded hydrogen atoms per molecule, and (C) hydrosilylation catalyst particles that have a microcapsule structure in which a platinum group metal catalyst-containing organic compound or polymer compound (C') serves as a core substance, while a three-dimensional crosslinked polymer compound obtained by polymerizing at least one type of a polyfunctional monomer (C") serves as a wall substance, wherein [solubility parameter of (C")]-[solubility parameter of (C')] is at least 1.0. Since the hydrosilylation catalyst particles having a specific structure are used in this addition-curable silicone composition, it is possible to prevent the silicone composition from being cured prior to the originally intended curing process when the composition is exposed to extremely high temperature exceeding 200°C, and to maintain the activity of the hydrosilylation catalyst.