Injectable Liquid Metal Interface for Direct-Cooled Power Modules
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Solution Overview
Problem
Current thermal interface materials (TIMs) used to couple power semiconductor devices to heat sinks face challenges in balancing thermal conductivity and contact resistance, with many materials either offering low thermal conductivity or leaving air gaps due to inconsistent surface morphology, which hampers effective heat dissipation.
Innovation Solution
The use of an injectable conductive component, such as a liquid solder alloy with low viscosity and high thermal conductivity, that remains in a liquid phase at operating temperatures, filling the interface gaps and ensuring continuous contact between the semiconductor device and the heat sink, thereby enhancing heat transfer without the reliability risks associated with solid bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional thermal interface materials are used to couple power semiconductor devices to heat sinks, then thermal conductivity is improved, but air gaps remain due to inconsistent surface morphology reducing heat transfer efficiency
Solution Approach 1:
The patent changes the physical state of the thermal interface material from solid to liquid, allowing it to flow and fill surface irregularities. The liquid solder alloy maintains a liquid phase at operating temperatures, enabling it to conform to inconsistent surfaces while maintaining high thermal conductivity and eliminating air gaps that plague traditional solid TIMs.
Solution Approach 2:
The patent applies hydraulic principles by using a liquid medium (solder alloy) to fill the interface between the heat sink and power module. The liquid flows under pressure to completely fill the cavity, ensuring no air pockets remain, similar to how hydraulic fluids fill and seal gaps in fluid systems.
2Stability of the object's composition
If solid thermal interface materials are used, then structural stability is improved, but they leave air gaps due to surface morphology inconsistencies
Solution Approach 1:
The patent changes the physical state of the thermal interface material from solid to liquid, allowing it to flow and fill surface irregularities. The liquid solder alloy maintains a liquid phase at operating temperatures, enabling it to conform to inconsistent surfaces while maintaining high thermal conductivity and eliminating air gaps that plague traditional solid TIMs.
Solution Approach 2:
The patent uses a composite structure combining the liquid solder alloy with the solid heat sink and power module components. The liquid metal forms a continuous phase that bridges the interface, creating a composite thermal path that combines the structural stability of solids with the conformability of liquids.
3Temperature
If liquid solder alloy is injected into the cavity, then continuous contact and heat transfer are improved, but containment and positioning challenges arise
Solution Approach 1:
The perimeter wall acts as an intermediary structure that contains the liquid solder alloy. This wall provides the necessary containment for the liquid metal while maintaining thermal pathways, solving the challenge of holding a liquid interface material in place without compromising heat transfer.
Solution Approach 2:
The perimeter wall functions as a thin containment barrier that holds the liquid solder alloy in place. This shell-like structure provides containment while minimizing thermal resistance, allowing the liquid metal to maintain continuous contact with both the heat sink and power module surfaces.
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
This approach significantly improves heat transfer efficiency by maintaining low viscosity and high thermal conductivity, ensuring reliable contact and effective heat dissipation from high-power semiconductor devices to heat sinks, addressing the limitations of existing TIMs.
Implementation Method 1
an injectable conductive component, such as a liquid solder alloy with low viscosity and high thermal conductivity, that remains in a liquid phase at operating temperatures
Implementation Method 2
filling the interface gaps and ensuring continuous contact between the semiconductor device and the heat sink
Data Source
AI summary
An injectable conductive component can be used to couple a high-power semiconductor chip assembly to a heat sink, in automotive and industrial applications. The injectable conductive component provides a low-resistance interface material and also acts as a bonding agent. A cavity bounded by the chip assembly and the heat sink can form a container for the injectable conductive component, which remains in a liquid phase during operation of the chip assembly. The container can be formed as a cavity by either removing a portion of the heat sink, or by introducing a spacer between the chip assembly and the heat sink, using a sealing material. The injectable conductive component can be introduced into the cavity by injection through a hole formed in a back side of the heat sink.