Copper-Ceramic Bonded Substrate With Low-Dislocation Copper for Heat Cycles
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Solution Overview
Problem
Existing copper-ceramic bonded substrates face challenges in achieving good heat cycle properties without increasing the outer size of the substrate, particularly when subjected to repeated heat loads during assembly and usage.
Innovation Solution
A copper-ceramic bonded substrate with a copper sheet bonded to a ceramic substrate, where the copper sheet has a dislocation density of 1.5×10^13 m^-2 or less, and specific impurity elements such as arsenic, antimony, sulfur, phosphorus, and zinc are controlled within certain ppm ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stepped shape or dimples are provided on the metal sheet to alleviate thermal stress, then thermal stress is reduced, but the mounting area for electronic components is reduced, requiring an increase in external size
Solution Approach 1:
Instead of changing the geometric shape (stepped structure or dimples), the invention changes the material parameter (dislocation density) of the copper sheet. By controlling dislocation density to 1.5×10^13 m^-2 or less, the copper sheet itself can withstand thermal stress without requiring geometric modifications, thus preserving the full mounting area while maintaining thermal stress resistance.
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 approach enables high heat cycle resistance without increasing the substrate's size, reducing damage to the ceramic substrate from heat loads, and suppressing work hardening of the copper sheet.
Implementation Method 1
a dislocation density of the copper sheet is 1.5×10^13 m^-2 or less
Implementation Method 2
suppressing work hardening of the copper sheet
Implementation Method 3
a thermal stress caused by a difference in thermal expansion between the ceramic substrate and the metal circuit board
Data Source
AI summary
There is provided a copper-ceramic bonded substrate, including: a ceramic substrate; and a copper sheet bonded to at least one surface of the ceramic substrate, wherein a dislocation density of the copper sheet is 1.5×1013 m−2 or less.