Transient Liquid Phase Bonding with Barrier Layers
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Solution Overview
Problem
In the field of electrical and electronic device fabrication, there are challenges in creating conductive surfaces or bonds that are thermally and electrically conductive, including high costs, incompatibility with other process steps due to high temperatures, difficulty in filling hollow features, and outgassing of byproducts.
Innovation Solution
A bonding structure is developed using multiple layers of alloy components with different melting points, where a first alloy component with a higher melting point is paired with a second alloy component of lower melting point, along with barrier layers to prevent oxidation and inter-diffusion, allowing for the formation of a conductive alloy when heated within a specific temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature processing is used to form conductive bonds, then bonding strength is improved, but compatibility with other process steps deteriorates
Solution Approach 1:
The invention changes the temperature parameter by using a two-stage bonding process: first bonding at a lower temperature (below the melting point of the sacrificial material) and then heating to a higher temperature (above the melting point of the sacrificial material) to complete the bonding and remove the sacrificial material. This resolves the contradiction by allowing initial bonding at compatible temperatures and achieving strong final bonds at higher temperatures only when necessary.
Solution Approach 2:
The invention introduces a sacrificial material as an intermediary substance between the bonding surfaces. This sacrificial material has a melting point lower than the final bonded structure, allowing it to facilitate bonding at lower temperatures and then be removed by selective melting, enabling strong bonds without requiring the entire structure to withstand high temperatures throughout the process.
2Reliability
If multiple alloy layers are used to achieve desired melting point, then bonding performance is improved, but device complexity increases
Solution Approach 1:
The invention uses composite material structures with multiple alloy layers having different melting points. A first alloy layer with higher melting point provides structural stability, while a second alloy layer with lower melting point enables controlled bonding and sacrificial material removal. This composite approach resolves the contradiction by achieving reliable bonding performance through material composition rather than structural complexity.
3Manufacturing precision
If barrier layers are added to prevent oxidation and inter-diffusion, then material purity is improved, but manufacturing complexity increases
Solution Approach 1:
The invention employs barrier layers that provide oxidation prevention and inter-diffusion control during the bonding process. These layers are designed to perform their protective function automatically during heating and bonding operations without requiring additional active control or intervention, thereby achieving material purity improvement while minimizing the increase in manufacturing complexity.
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 method enables the formation of a hermetically sealed electronic device with improved conductivity and reduced processing costs, effectively addressing the challenges of surface roughness and topology, while maintaining a higher melting point than the bonding temperature.
Implementation Method 1
the second alloy component has a lower melting temperature than the first alloy component... when the bonding structure is heated to a temperature above the melting temperature of the second alloy component
Implementation Method 2
The first alloy component and the second alloy component are selected to inter-diffuse and form an alloy when the bonding structure is heated
Implementation Method 3
a first barrier layer configured to seal a surface of the second layer of the second alloy component from atmosphere and suppress oxidation of the surface
Implementation Method 4
interfacial barrier layers disposed at interfaces between each layer of the first alloy component and each layer of the second alloy component, the barrier layers configured to suppress inter-diffusion
Data Source
AI summary
A method of forming a bonding element including a first transient liquid phase (TLP) bonding element including a first material and a second material, the first material having a higher melting point than the second material, a ratio of a quantity of the first material and the second material in the first TLP bonding element having a first value, and a second TLP bonding element including the first material and the second material, a ratio of a quantity of the first material and the second material in the second TLP bonding element having a second value different from the first value.