Addition-Curing Silicone With Aluminum Oxide for Stable Hardness
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Solution Overview
Problem
Existing thermally conductive silicone compositions face issues with stability over time, hardness changes, and insufficient thermal conductivity, particularly when used in electronic components, leading to potential damage and reduced insulation ability.
Innovation Solution
A thermally conductive addition-curable silicone composition is formulated by mixing aluminum oxide with controlled Na+ ion content, alkenyl-group-containing organopolysiloxane, and organohydrogenpolysiloxane, along with a platinum-based catalyst and ion trap agent, to enhance storability and reduce hardness changes, achieving thermal conductivity of 1.0 to 7.0 W/m·K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If aluminum oxide powder is used as a thermally conductive filler, then thermal conductivity is improved, but hardness changes over time due to dehydrogenation reaction with Al-OH groups
Solution Approach 1:
The patent applies preliminary action by pre-treating the aluminum oxide powder surface with a silane coupling agent before incorporating it into the silicone composition. This preliminary surface treatment creates a protective layer that prevents subsequent dehydrogenation reactions between Al-OH groups and silicon-hydrogen bonds, thereby maintaining hardness stability over time while preserving thermal conductivity
Solution Approach 2:
The silane coupling agent acts as an intermediary substance between the aluminum oxide filler and the silicone base polymer. This intermediary layer on the filler surface prevents direct harmful interactions (dehydrogenation reactions) while maintaining the thermal conductivity pathway, thus resolving the contradiction between thermal performance and compositional stability
2Reliability
If silica powder is used as a filler, then electrical insulation and stability are improved, but thermal conductivity is insufficient
Solution Approach 1:
The patent employs composite materials by combining aluminum oxide powder (for thermal conductivity) with silicone base polymer (for electrical insulation and stability). The silane-modified aluminum oxide surface treatment ensures compatibility and prevents degradation, creating a composite system that achieves both good thermal conductivity and electrical insulation properties simultaneously
3Temperature
If high thermal conductivity is attempted to be imparted to the silicone composition, then thermal stress relaxation is improved, but viscosity deteriorates considerably
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution and surface treatment of the aluminum oxide filler. The silane coupling agent treatment modifies the surface properties of the filler particles, improving their dispersion in the silicone base polymer. This reduces aggregation and maintains lower viscosity while achieving high thermal conductivity, thus resolving the contradiction between thermal performance and operability
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 provides excellent stress relaxation and thermal conductivity, ensuring protection and insulation for electronic components while maintaining stability over time, suitable for circuit substrates.
Implementation Method 1
thermally conductive silicone compositions are used... Use of a filler having good thermal conductivity is known to relax the thermal stress... aluminum oxide powder... thermal conductivity of 1.0 to 7.0 W/m·K
Implementation Method 2
addition-curable silicone composition... comprising: a heat-treated mixture containing (A) an organopolysiloxane having at least two alkenyl groups bonded to a silicon atom... (B) an organohydrogenpolysiloxane... (E) a platinum-based catalyst
Implementation Method 3
ion trap agent... Simultaneously mixing and heat-treating aluminum oxide, as a thermally conductive filler, whose Na+... reduce the change in hardness over time... excellent storability and reduced change in hardness over time
Implementation Method 4
heat-treated mixture... Simultaneously mixing and heat-treating aluminum oxide... heat-treating a mixture containing (A) to (C) at a temperature of 70°C or higher to surface-treat the (C)
Data Source
AI summary
The present invention is a thermally conductive addition-curable silicone composition, including: a heat-treated mixture including (A) an organopolysiloxane having at least two alkenyl groups bonded to a silicon atom in one molecule, (B) an organohydrogenpolysiloxane having at least three hydrogen atoms bonded to a silicon atom in one molecule, and (C) aluminum oxide; (D) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule; (E) a platinum-based metal catalyst; and (F) a cation-exchange type and/or both-ions-exchange type ion trap agent. This provides a thermally conductive addition-curable silicone composition that can be applied on electric and electronic components and in a module including a circuit substrate mounting these components thereon and that can exhibit excellent stress relaxation property and thermal conductivity after cured. In addition, the present invention provides a method for producing the same.