Silicon Nitride Copper Bonded Substrate With Gradient Bonding Layer
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Solution Overview
Problem
Conventional bonded substrates with silicon nitride ceramics and copper plates often face incompatible adhesion strengths between the ceramic substrate and the bonding layer, and between the copper plate and the bonding layer, resulting in suboptimal bonding strength and reliability, especially in thermal cycling applications.
Innovation Solution
A bonded substrate design featuring a bonding layer with a specific distribution of atomic fractions, where nitrogen is greatest at the interface with the silicon nitride ceramic substrate and the sum of active metal and silicon is greatest at the interface with the copper plate, forming strong bonds with both materials, thereby enhancing adhesion strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional brazing materials (Ag-Cu-Ti) are used with uniform composition, then the bonding process is simple, but the adhesion strength between ceramic substrate and bonding layer and between copper plate and bonding layer cannot be simultaneously optimized
Solution Approach 1:
The bonding layer is designed with non-uniform composition distribution: nitrogen concentration is highest at the ceramic substrate interface to form strong TiN bonds, while active metal and silicon concentration is highest at the copper plate interface to form strong metallurgical bonds. This local quality variation resolves the contradiction by optimizing adhesion strength at each interface independently.
Solution Approach 2:
The invention changes the compositional parameters of the bonding layer from uniform to gradient distribution. By controlling the atomic fractions of nitrogen, active metal, and silicon at different positions within the bonding layer, the adhesion strength at both interfaces is simultaneously enhanced without requiring complex multi-layer structures.
2Reliability
If the bonding layer is optimized for copper plate adhesion, then thermal cycling reliability is improved, but adhesion strength at the ceramic substrate interface deteriorates
Solution Approach 1:
The bonding layer simultaneously optimizes local composition at each interface: nitrogen-rich region at the ceramic substrate interface for strong adhesion, and active metal-silicon rich region at the copper plate interface for thermal cycling reliability. This resolves the contradiction by addressing both requirements locally rather than globally.
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 a bonded substrate with higher adhesion between the silicon nitride ceramic substrate and the bonding layer, and between the copper plate and the bonding layer, achieving improved bonding strength and reliability.
Implementation Method 1
The bonding layer includes, as a major component, titanium nitride as a product of reaction of titanium derived from the titanium hydride powder and nitrogen derived from the silicon nitride ceramic substrate
Implementation Method 2
changing the brazing material layer into the bonding layer through thermal treating on the prepared intermediate product
Data Source
AI summary
A bonded substrate includes: a silicon nitride ceramic substrate; a copper plate; and a bonding layer bonding the copper plate to the silicon nitride ceramic substrate, wherein the bonding layer has a first interface in contact with the silicon nitride ceramic substrate and a second interface in contact with the copper plate, and contains a nitride and a silicide of an active metal as at least one metal selected from the group consisting of titanium and zirconium, an atomic fraction of nitrogen of the bonding layer is greatest at the first interface and is smallest at the second interface, and a sum of atomic fractions of the active metal and silicon of the bonding layer is smallest at the first interface and is greatest at the second interface.