Ag-Cu-Ti Bonding Layer for Etch-Controlled Ceramic Circuit Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ceramic-copper circuit substrates face challenges in controlling the size of the bonding layer protruded portion during the etching process, resulting in variable TCT characteristics and reduced yield.
Innovation Solution
A bonded assembly is developed with a bonding layer containing Ag, Cu, and Ti, where the Ag-rich region has a concentration of 60 at % or more and an area ratio of 70% or less to the Ag-poor region, improving bonding strength and etching properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding layer containing Ag, Cu and Ti is formed by an active metal bonding method, then bonding strength is improved, but the size of the bonding layer protruded portion cannot be controlled precisely during etching
Solution Approach 1:
The bonding layer is designed with non-uniform Ag concentration distribution, creating Ag-rich regions (60-80 at% Ag) and Ag-poor regions (30-50 at% Ag) with different etching rates. This local variation in composition allows the protruded portion size to be controlled by the etching process, while the overall bonding strength is maintained through the presence of Ti and the mixed Ag-Cu structure.
2Reliability
If the bonding layer has a mixed structure of Ag and Cu, then bonding properties are improved, but the etching effect varies causing variation in protruded portion size
Solution Approach 1:
The bonding layer incorporates localized Ag-rich regions surrounded by Ag-poor regions, creating a hierarchical structure where different local compositions provide different functions. The Ag-rich regions offer superior bonding properties and corrosion resistance, while the Ag-poor regions etch more readily to form the desired protruded portion geometry with consistent dimensions.
Solution Approach 2:
The bonding layer is designed as a composite material system combining Ag, Cu, and Ti in specific proportions and distributions. The Ag provides bonding strength and corrosion resistance, Cu enhances ductility and electrical conductivity, and Ti forms intermetallic compounds with the ceramic substrate. The non-uniform distribution of these elements creates regions with tailored properties for both bonding and etching functions.
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 controlled distribution of Ag-rich and Ag-poor regions enhances the bonding strength and etching properties, allowing for precise control of the bonding layer protruded portion and improved TCT characteristics.
Implementation Method 1
a bonding layer containing Ag, Cu and Ti... formed by an active metal bonding method
Implementation Method 2
an etching process is employed for controlling the size of the bonding layer protruded portion... The etching process is a process for removing the copper plate and the bonding layer
Data Source
AI summary
A bonded assembly according to the present embodiment, includes a metal plate and a ceramic substrate bonded to each other through a bonding layer containing Ag. In the bonded assembly, in a measurement region that is formed in a cross section formed by a thickness direction of the bonding layer and an orthogonal direction thereto, and that has a size of a length in the thickness direction of the bonding layer×a length of 200 μm in the orthogonal direction, a Ag-rich region having a Ag concentration of 60 at % or more has an area ratio of 70% or less to a Ag-poor region having a Ag concentration of 50 at % or less.