Copper-Ceramic Assembly With MgO Interface for Thermal Cycle Reliability
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Solution Overview
Problem
High-temperature semiconductor devices with SiC require enhanced bonding reliability between copper and ceramic substrates to withstand severe thermal cycles and prevent peeling during ultrasonic welding, as existing methods fail to ensure reliable bonding and crack suppression.
Innovation Solution
A copper/ceramic bonded body is created with a magnesium oxide layer between the copper and ceramic members and an active metal oxide phase dispersed within the copper layer, using Ti, Zr, or Hf oxides, to reduce thermal stress and strengthen the bonded interface, with specific thickness and particle size ranges for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If active metal brazing method with Ag-Cu-Ti-based brazing material is used to bond copper sheet to ceramic substrate, then bonding strength is improved, but cracks are generated at bonded interface during ultrasonic welding
Solution Approach 1:
The invention changes the chemical composition parameters of the brazing material from Ag-Cu-Ti to Cu-Mg-Ti alloy, and adjusts the bonding temperature parameters to 560-800°C in nitrogen atmosphere. This parameter change transforms the bonding mechanism to enable Mg sublimation, which prevents crack generation during subsequent ultrasonic welding while maintaining strong bonding between copper and ceramic substrates.
Solution Approach 2:
The invention utilizes the phase transition of magnesium from solid to gas (sublimation) during the bonding process. The Mg in the Cu-Mg-Ti alloy sublimes at the bonding temperature range, leaving behind a clean interface that prevents crack formation during ultrasonic welding, while still achieving reliable bonding through the Ti component and controlled Mg reaction.
2Adaptability or versatility
If high-density semiconductor elements are mounted on insulating circuit substrate, then device functionality is improved, but bonding reliability deteriorates under severe thermal cycles
Solution Approach 1:
The invention changes the material composition parameters of the brazing alloy to Cu-Mg-Ti and adjusts the bonding temperature to 560-800°C in nitrogen atmosphere. This creates a more thermally stable bonded interface that can withstand severe thermal cycling conditions, enabling high-density semiconductor mounting without compromising bonding reliability under thermal stress.
3Reliability
If copper sheet is bonded to ceramic substrate using conventional brazing, then electrical conductivity is improved, but peeling occurs during ultrasonic welding
Solution Approach 1:
The invention changes the brazing material composition to Cu-Mg-Ti alloy and controls the bonding temperature range (560-800°C) and atmosphere (nitrogen). This parameter optimization ensures adequate electrical conductivity through the copper layer while the Mg sublimation process creates a crack-free interface that maintains bonding strength during ultrasonic welding operations.
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 solution ensures reliable bonding between copper and ceramic members under severe thermal cycles and suppresses peeling and crack generation during ultrasonic welding, enhancing the durability and performance of insulating circuit substrates.
Implementation Method 1
a magnesium oxide layer is formed on a ceramic member side between the copper member and the ceramic member
Implementation Method 2
an active metal oxide phase composed of an oxide of one or more active metals selected from Ti, Zr, Nb, and Hf is dispersed inside a copper layer in contact with the magnesium oxide layer
Implementation Method 3
a terminal material or the like may be subjected to ultrasonic welding
Data Source
AI summary
This A copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of oxygen-containing ceramics, wherein the copper member and the ceramic member are bonded to each other, a magnesium oxide layer is formed on a ceramic member side between the copper member and the ceramic member, and an active metal oxide phase composed of an oxide of one or more active metals selected from Ti, Zr, Nb, and Hf is dispersed inside a copper layer in contact with the magnesium oxide layer.