Cu/Ceramic Bonding via Ag-Ti Interlayer for Low-Temp Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bonding methods for copper and ceramic substrates, such as DBC and active metal brazing, require high temperatures, leading to potential deterioration of the ceramic substrate and reduced bonding reliability due to insufficient reaction of the brazing filler metal at lower temperatures.
Innovation Solution
A Cu/ceramic bonded body is formed using a bonding material containing Ag and Ti, where a Ti compound layer and Ag particles are dispersed at the bonding interface, allowing for reliable bonding at lower temperatures by forming a Ti nitride or oxide layer through a eutectic reaction between Ag and Al, with Ag particles dispersed in the Ti compound layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If DBC method is used to bond copper plates to ceramic substrate, then bonding strength is improved, but bonding temperature must be set to 1065°C or higher causing deterioration of ceramic substrate
Solution Approach 1:
The patent introduces a bonding material containing Ag and Ti as an intermediary substance between the copper member and ceramic member. This bonding material enables reliable bonding at lower temperatures (avoiding 1065°C+) by forming a Ti compound layer that facilitates adhesion without requiring the high eutectic temperature of the DBC method, thus resolving the contradiction between bonding strength and bonding temperature.
2Reliability
If active metal brazing method is used with Ag-Cu-Ti brazing filler metal, then wettability between melted brazing filler metal and ceramic substrate is improved, but bonding temperature must be set to 900°C causing deterioration of ceramic substrate
Solution Approach 1:
The patent changes the bonding temperature parameter from the conventional 900°C (active metal brazing) to a lower temperature range. By using a bonding material containing Ag and Ti that forms a Ti compound layer, the method achieves reliable bonding at reduced temperatures, thereby improving bonding reliability while avoiding ceramic substrate deterioration caused by high temperature exposure.
3Temperature
If bonding temperature is lowered below 900°C in active metal brazing method, then deterioration of ceramic substrate is reduced, but brazing filler metal does not sufficiently react with ceramic substrate causing decreased bonding rate
Solution Approach 1:
The Ti component in the bonding material acts as a reactive intermediary that forms a Ti compound layer (Ti nitride or Ti oxide) at the bonding interface. This intermediate layer facilitates sufficient reaction between the bonding material and ceramic substrate even at lower temperatures, thereby maintaining high bonding rates while enabling reduced bonding temperatures that protect the ceramic substrate from deterioration.
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 strong and reliable bonding of copper and ceramic members at lower temperatures, reducing thermal stress on the ceramic substrate and improving bonding reliability while maintaining energy efficiency.
Implementation Method 1
a Ti compound layer made of a Ti nitride or a Ti oxide is formed at a bonding interface between the copper member and the ceramic member
Implementation Method 2
forming a Ti nitride or oxide layer through a eutectic reaction between Ag and Al, with Ag particles dispersed in the Ti compound layer
Implementation Method 3
by utilizing a eutectic reaction between copper and a copper oxide, a liquid phase is formed at the interface between the copper plate and the ceramic substrate to bond the copper plate to the ceramic substrate
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A Cu/ceramic bonded body according to the present invention is formed by bonding a copper member made of copper or a copper alloy and a ceramic member made of AlN or Al2O3 using a bonding material containing Ag and Ti, in which a Ti compound layer made of a Ti nitride or a Ti oxide is formed at a bonding interface between the copper member and the ceramic member, and Ag particles are dispersed in the Ti compound layer.