Liquid Metal TIM Alloy Bonding Without Backside Metallization
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Solution Overview
Problem
Conventional thermal interface materials face challenges in providing efficient heat dissipation and mechanical stability for semiconductor devices, particularly due to the need for backside metallization and the risk of chip damage during compression.
Innovation Solution
The use of a layered thermal interface material comprising a solid metal foam and liquid metal, which forms an alloy upon compression, eliminating the need for backside metallization and enhancing thermal conductivity and mechanical bonding without damaging the semiconductor chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermal interface materials are used, then thermal conductivity can be improved, but backside metallization is required and chip damage risk increases during compression
Solution Approach 1:
The patent removes the backside metallization layer from the semiconductor device structure. Instead of requiring complex multi-layer metallization (reactive layer, barrier layer, passivation layer) on the chip backside, the invention uses a simplified thermal interface material system consisting of a compression layer and a thermal interface material that directly bonds to the chip surface without metallization, thereby eliminating the harmful complexity while maintaining thermal conductivity.
2Strength
If compression is applied to bond thermal interface material, then mechanical bonding strength is improved, but chip damage risk increases
Solution Approach 1:
The patent introduces a compression layer positioned between the thermal interface material and the semiconductor chip. This compression layer acts as a cushioning element that absorbs and distributes compressive forces during the bonding process, preventing excessive stress from reaching the fragile chip structure. The layer provides mechanical protection beforehand, allowing strong bonding to be achieved without chip damage.
3Temperature
If indium metal is used as thermal interface material, then thermal conductivity and malleability are improved, but mechanical strength without external fixturing is insufficient
Solution Approach 1:
The patent creates a composite thermal interface system combining two distinct materials: a compression layer (which can be foam, gel, or other compressible material) and a thermal interface material (such as indium metal). The compression layer provides the necessary mechanical strength and structural support, while the thermal interface material maintains high thermal conductivity. This composite structure allows the system to achieve both thermal performance and mechanical strength without requiring external fixturing mechanisms.
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 provides improved thermal conductivity and mechanical stability, reducing the risk of chip damage and eliminating the need for additional metallization, while maintaining structural integrity and enhancing compressibility.
Implementation Method 1
the liquid metal diffuses through the porous features of the solid metal foam and bonds to the semiconductor device surface
Implementation Method 2
forming an alloy that provides thermal conduction and mechanical attachment
Implementation Method 3
compressing the solid metal foam with the liquid metal
Implementation Method 4
provide a more efficient and reliable conduction of heat from the device to the heatsink
Data Source
AI summary
Liquid metal thermal interface materials and their uses in electronics assembly are described. In one implementation, a semiconductor assembly includes: a semiconductor die; a heat exchanger; and a thermal interface material (TIM) alloy bonding the semiconductor die to the heat exchanger without using a separate metallization layer on a surface of the semiconductor die or a surface of the heat exchanger. The TIM alloy may be formed by placing a TIM material between the semiconductor die and the heat exchanger, the TIM material comprising a first liquid metal foam in touching relation with the surface of the semiconductor die, a second liquid metal foam in touching relation with the surface of the heat exchanger.