Silicone Interface Material for Circuit Board Thermal Management
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Solution Overview
Problem
Existing thermoset polymer-based interface materials for high or low frequency circuit boards are inflexible and have limited temperature stability, leading to weakening or delamination at the circuit/heat sink interface due to high heat generation, especially in high power electronic components.
Innovation Solution
A silicone-based electrically and thermally conductive interface material composed of a mixture of silicone compound, metal flakes or granules, flame retardant, and curing catalyst, applied as a film or screen-printable paste, which is sandwiched between a printed circuit board and a heat sink, and cured through a multi-step press process to form a laminate, providing mechanical bonding and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoset polymer-based interface materials are used, then electrical and thermal conductivity is achieved, but temperature stability deteriorates above 400 F causing weakening or delamination
Solution Approach 1:
The patent changes the fundamental material parameter from thermoset polymer to silicone-based compound, which fundamentally alters the temperature stability parameter. Silicone-based materials maintain their physical properties and flexibility at temperatures above 400 F where thermoset polymers degrade, directly resolving the temperature stability issue while maintaining electrical and thermal conductivity through metal flake incorporation.
Solution Approach 2:
The interface material is formulated as a composite consisting of silicone-based compound as the base matrix, combined with metal flakes or granules for electrical and thermal conductivity, and flame retardant additives. This composite structure allows the silicone to provide high-temperature stability while the metal components maintain the required conductive properties.
2Reliability
If thermoset polymer-based interface materials are used, then electrical and thermal conductivity is achieved, but flexibility deteriorates causing inability to expand or contract with temperature changes
Solution Approach 1:
The patent changes the material composition parameter from rigid thermoset polymer to flexible silicone-based compound. This parameter change fundamentally alters the mechanical properties, allowing the interface material to expand and contract with temperature changes while maintaining continuous electrical and thermal pathways through the embedded metal flakes.
3Temperature
If silicone-based interface material is used, then temperature stability is improved, but manufacturing complexity increases due to multi-step press process
Solution Approach 1:
The interface material is pre-formulated with all necessary components (silicone-based compound, metal flakes, flame retardant, curing catalyst) in the correct proportions and mixed homogeneously before application. This preliminary preparation of the material composition simplifies the manufacturing process by eliminating the need for complex multi-component mixing and application procedures during assembly.
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 solution enhances the thermal conductivity and mechanical bonding between the circuit board and heat sink, maintaining stability across varying temperatures, preventing delamination and ensuring reliable operation in high-frequency applications such as wireless communication systems and radiofrequency systems.
Implementation Method 1
An electrically and thermally conductive interface material is provided as a mixture of a silicone-based compound, metal flakes and/or granules, flame retardant and a curing catalyst
Implementation Method 2
Each side of the film may also include a coating of an adhesive material that aids in coupling the interface film with a metal surface
Implementation Method 3
a mixture of a silicone-based compound, metal flakes and/or granules, flame retardant and a curing catalyst
Data Source
AI summary
A thermally and electrically conductive material is provided as a mixture of a dimethylpolysiloxane, metal (or one metal coated with another metal) flakes and/or granules, a peroxide-based and/or a dimethyl hexane based catalyst, PTFE powder and a platinum based fire retardant. The thermally and electrically conductive material may be pre-formed into a film or pad and each side of the film protected with removable release layers. The thermally and electrically conductive material may alternatively be produced in a screen-printable paste. As such, a layer of the thermally and electrically conductive paste may be screen-printed on the metal surface in a complete sheet form or as a patterned film by using a stencil patterned screen mesh. Processes for manufacturing high- and low-frequency circuits that include the interface material are also provided.