Metal Foil Thermal Interface with Solid Lubricant Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermal interface materials used in power electronic modules fail to effectively manage heat transfer due to mechanical stresses and deformation caused by cyclic loading and temperature variations, leading to premature component breakdown.
Innovation Solution
A metal foil with a solid lubricant coating, such as graphite or PTFE, is used as a thermal interface material between the base plate and the cooling surface, which withstands deformation and mechanical stresses, ensuring continuous heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal interface materials (grease, rubber pads, metal foils) are used, then heat transfer is initially improved, but the materials fail under cyclic loading and temperature variations leading to premature breakdown
Solution Approach 1:
The patent uses a composite structure consisting of a metal foil base layer combined with a polymer coating layer. The metal foil provides mechanical strength and thermal conductivity, while the polymer coating provides lubrication and compliance to accommodate cyclic deformation. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both heat transfer efficiency and durability under cyclic loading.
Solution Approach 2:
The patent changes the physical and chemical parameters of the thermal interface material by selecting specific metal foils (aluminum, copper, silver) with particular thermal conductivities and combining them with polymers having specific glass transition temperatures and lubrication properties. This parameter optimization ensures the material maintains its functional properties across the operational temperature range and under cyclic mechanical stress.
2Reliability
If the base plate surface is made perfectly smooth and planar to reduce contact thermal resistance, then heat transfer is improved, but the cost increases significantly
Solution Approach 1:
The patent introduces a thermal interface material as an intermediary substance between the base plate and heat sink. This TIM fills the gaps and air pockets that exist between imperfectly matched surfaces, providing continuous thermal conduction paths without requiring expensive precision machining of the mating surfaces. The material acts as a mediator that compensates for surface imperfections while maintaining effective heat transfer.
Solution Approach 2:
The patent employs a compliant polymer-coated metal foil structure that can deform to conform to surface irregularities. The polymer layer's compliance allows it to fill voids and adapt to the actual contact topology, effectively creating thermal conduction paths through what would otherwise be air gaps, thereby maintaining heat transfer efficiency without requiring perfectly flat surfaces.
3Reliability
If graphite thermal interface materials are used for small footprint devices, then heat transfer is improved, but the material is too hard and cannot accommodate the large footprint and non-planar surface of power electronic base plates
Solution Approach 1:
The patent applies a thin polymer coating layer (1-10 μm) on the metal foil surface, creating a localized compliant layer only where needed for surface conformity. This thin coating provides the necessary compliance and lubrication at the contact interface while the bulk metal foil maintains its structural integrity and thermal conductivity. This local application of compliance resolves the contradiction between hardness and adaptability.
Solution Approach 2:
The patent transitions from using purely solid, rigid thermal interface materials (like graphite) to a composite structure with a flexible polymer coating dimension. This adds a compliant dimension to the interface material, allowing it to deform and conform to the non-planar base plate surface while still providing effective thermal conduction through the metal foil substrate.
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 effectively maintains heat transfer efficiency by preventing mechanical failure of the thermal interface material, reducing the risk of component overheating and extending the operational lifetime of power electronic modules.
Implementation Method 1
a thermal interface material comprising a metal foil and a solid lubricant coating... to transfer heat from the power electronic module to the cooling arrangement
Implementation Method 2
a layer of solid lubricant coating... which withstands deformation and mechanical stresses
Data Source
Figure 1~2
Figure 3
AI summary
A method of producing a power electronic assembly and a power electronic assembly comprising a power electronic module incorporating multiple of semiconductor power electronic switch components, the power electronic module comprising a base plate with a bottom surface, the power electronic assembly comprises further a cooling arrangement for cooling the power electronic module, the cooling arrangement comprising a cooling surface adapted to be attached against the bottom surface of the base plate of the power electronic module, wherein the power electronic assembly comprises further a thermal interface material arranged between the bottom surface of the base plate of the power electronic module and the cooling surface of the cooling arrangement to transfer heat from the power electronic module to the cooling arrangement, the thermal interface material comprises a metal foil and a solid lubricant coating.