Thermally Conductive Silicone Composition with Silver Filler
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Solution Overview
Problem
Heat-conductive silicone compositions used in semiconductor devices face challenges in achieving low thermal resistance while maintaining flexibility and reliability, as existing methods either fail to reduce thermal resistance effectively or compromise on flexibility due to the use of low-melting metals or solders with low thermal conductivity.
Innovation Solution
A heat-conductive silicone composition is developed using a specific combination of organopolysiloxane, organohydrogenpolysiloxane, a platinum complex catalyst, and silver powder, which balances flexibility after curing, shelf stability, and low thermal resistance by optimizing the ratio of silicon-bonded hydrogen atoms to alkenyl groups and the type of platinum complex catalyst used, along with additional components like inhibitors and heat-conductive fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-melting metal is added to heat-dissipating grease for curing, then thermal contact resistance is reduced, but the thermal conductivity of the composition remains low
Solution Approach 1:
The patent uses a composite material system combining organopolysiloxane with alkenyl groups, organohydrogenpolysiloxane with Si-H groups, and silver powder filler. This composite approach allows the silicone composition to achieve both low thermal contact resistance through chemical bonding and high thermal conductivity through the silver filler, resolving the contradiction between contact resistance reduction and thermal conductivity maintenance
Solution Approach 2:
The patent changes the chemical parameters by specifying the ratio of Si-H groups to alkenyl groups (1.05-1.30 molar ratio) and controlling the vinyl group content (0.03-0.10 mmol/g). These parameter optimizations enable efficient crosslinking that reduces thermal contact resistance while maintaining the thermal conductivity properties of the silver filler
2Reliability
If solder containing high thermal conductivity metal is used, then thermal conductivity should improve, but the composition still has low thermal conductivity
Solution Approach 1:
The patent optimizes the silver powder filler content (5-80 wt%) and controls the molecular structure parameters of the polysiloxane components. By adjusting these parameters, the composition achieves both high thermal conductivity from the silver filler and low thermal contact resistance through proper crosslinking density
3Ease of operation
If catalyst amount is increased to form crosslink structure for maintaining flexibility, then flexibility is improved, but pot life becomes extremely short
Solution Approach 1:
The patent optimizes the catalyst amount to a specific range (0.003-0.010 wt% platinum) and controls the ratio of reactive groups (1.05-1.30 molar ratio of Si-H to alkenyl groups). This parameter optimization enables sufficient crosslinking for flexibility while controlling the reaction rate to maintain adequate pot life for processing
Solution Approach 2:
The patent uses a moderate amount of catalyst and controls the crosslinking density through the ratio of functional groups. This partial action approach provides enough crosslinking to achieve flexibility while avoiding excessive crosslinking that would cause extremely short pot life, balancing both requirements
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 achieves both flexibility and shelf stability in one-part form with excellent thermal properties, resulting in very low thermal resistance and improved reliability, making it suitable for high-grade equipment like servers and IGBTs.
Implementation Method 1
a platinum complex curing catalyst selected from the group consisting of trimethyl(acetylacetonato)platinum complex, trimethyl(2,4-pentanedionato)platinum complex, trimethyl(3,5-heptanedionato)platinum complex, trimethyl(methylacetoacetato)platinum complex, bis(2,4-pentanedionato)platinum complex, bis(2,4-hexanedionato)platinum complex, bis(2,4-heptanedionato)platinum complex, bis(3,5-heptanedionato)platinum complex, bis(1-phenyl-1,3-butanedionato)platinum complex, bis(1,3-diphenyl-1,3-propanedionato)platinum complex, (1,5-cyclooctadienyl)dimethyl platinum complex, (1,5-cyclooctadienyl)diphenyl platinum complex, (1,5-cyclooctadienyl)dipropyl platinum complex, (2,5-norbomadiene)dimethyl platinum complex, (2,5-norbornadiene)diphenyl platinum complex, (cyclopentadienyl)dimethyl platinum complex, (methylcyclopentadienyl)diethyl platinum complex, (trimethylsilylcyclopentadienyl)diphenyl platinum complex, (methylcycloocta-1,5-dienyl)diethyl platinum complex, (cyclopentadienyl)trimethyl platinum complex, (cyclopentadienyl)ethyldimethyl platinum complex, (cyclopentadienyl)acetyldimethyl platinum complex, (methylcyclopentadienyl)trimethyl platinum complex, (methylcyclopentadienyl)trihexyl platinum complex, (trimethylsilylcyclopentadienyl)trimethyl platinum complex, (dimethylphenylsilylcyclopentadienyl)triphenyl platinum complex, and (cyclopentadienyl)dimethyltrimethylsilylmethyl platinum complex
Implementation Method 2
an addition-curable heat-conductive silicone composition comprising a silver filler
Implementation Method 3
500 to 3,000 parts by weight of silver powder
Data Source
AI summary
With respect to an addition-curable thermally conductive silicone composition in which a silver filler is blended, a catalyst having a specific structure and an organohydrogen polysiloxane having a specific structure are used for the purpose of extending the working life at room temperature, while maintaining the flexibility, so that a thermally conductive silicone composition which is able to have a good balance between flexibility after curing and storage stability in one pack, while having extremely low thermal resistance and excellent reliability is achieved.