Multilayer Bonding Interface for Aluminum Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to achieve high bonding reliability and electrical conductivity in electronic element devices with electrodes made of Al or Al alloys while simplifying the manufacturing process and reducing costs, particularly in the presence of an Al oxide film that can hinder bonding.
Innovation Solution
A multilayer bonding interface structure is created, comprising a layer of Al, an Al oxide layer, an alloy of Al and metal nanoparticles, and a layer of metal nanoparticles, which allows for effective bonding between the Al electrode and the metal nanoparticle sintered body without pre-treating the Al oxide film, using a metal nanoparticle paste applied and sintered at a temperature that removes organic components, ensuring the metal nanoparticles maintain their activity and form a strong alloy layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder bonding is used with Al electrodes, then electrical conductivity is achieved, but the Al oxide film on the electrode surface hinders bonding reliability
Solution Approach 1:
The patent introduces a metal nanoparticle paste as an intermediary bonding material between the Al electrode and the opposing electrode. This paste contains metal nanoparticles (such as Ag, Cu, or Au) dispersed in an organic vehicle, which facilitates bonding by bridging the Al oxide film barrier and enabling reliable electrical connection without requiring complete removal of the oxide layer.
Solution Approach 2:
The patent changes the bonding parameters by using a low-melting-point metal nanoparticle paste that can be applied and cured at lower temperatures. The paste undergoes phase change from a paste state to a sintered metal state, transforming the bonding mechanism from mechanical adhesion to metallurgical bonding, thereby overcoming the oxide film barrier.
2Reliability
If pre-treatment of Al oxide film is performed to improve bonding, then bonding reliability increases, but manufacturing process complexity and cost increase
Solution Approach 1:
The metal nanoparticle paste performs self-service by automatically penetrating and bonding through the Al oxide film without requiring external pre-treatment processes. The paste's composition and application method enable it to self-adhere to the oxide surface and form reliable bonds, eliminating the need for separate oxide removal or surface activation steps.
Solution Approach 2:
The patent extracts the oxide film removal function from the manufacturing process by using a bonding material that does not require the oxide to be removed. Instead of taking out the oxide film through pre-treatment, the solution takes out the requirement for oxide removal by using a paste that bonds effectively through the existing oxide layer.
3Strength
If high temperature solder is used for first step bonding, then bonding strength is achieved, but environmental regulations against Pb usage become problematic
Solution Approach 1:
The patent changes the temperature parameter by using a metal nanoparticle paste with a lower curing temperature than conventional high-temperature solder. The paste can be cured at temperatures below 200°C, which is sufficient to evaporate the organic vehicle and sinter the metal nanoparticles, achieving strong bonds without requiring Pb-based high-temperature solder.
Solution Approach 2:
The bonding material is a composite consisting of metal nanoparticles (Ag, Cu, or Au) dispersed in an organic vehicle with additives. This composite structure provides both the low-temperature processability of the organic vehicle and the high-strength metallurgical bonding of the metal particles, replacing Pb-based solder while maintaining or improving bond strength.
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 results in electronic elements with high bonding reliability and electrical conductivity, simplifies the manufacturing process, and reduces costs by eliminating the need for pre-treatment of the Al oxide film and ensuring stable bonding even with Al or Al alloy electrodes.
Implementation Method 1
the metal nanoparticle paste is sintered by heating to form a metal nanoparticle sintered body that has bonded the first electrode and the second electrode to each other
Implementation Method 2
heating at a temperature equal to or higher than that at which the dispersing agent and the organic solvent included in the metal nanoparticle paste can be removed
Data Source
AI summary
An electronic element including an electronic element base and electrodes each of which has a first electrode having a surface composed of at least Al or an Al alloy and a second electrode composed of a metal nanoparticle sintered body and bonded to the first electrode. A bonding interface between the first electrode and the second electrode has a multilayer structure including, from the side of the first electrode to the side of the second electrode, (a) a first layer primarily composed of Al, (b) a second layer primarily composed of an Al oxide, (c) a third layer primarily composed of an alloy of Al and a constituent element of metal nanoparticles, and (d) a fourth layer primarily composed of the constituent element of the metal nanoparticles.