Ceramic Substrate Bonding With Matched Spacer for Faster Etching
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Solution Overview
Problem
The existing ceramic substrate manufacturing methods face challenges such as increased etching time, spacing between circuits, electroless plating requirements, and reduced bonding force due to thermal expansion and conductivity mismatches with spacers, particularly in active metal brazing (AMB) substrates used in applications like vehicles and wind turbines.
Innovation Solution
A ceramic substrate manufacturing method that involves etching and bonding a copper sheet on a ceramic substrate, using a brazing method with a spacer matching the thermal conductivity and expansion coefficient of the substrate, and partial electroplating to improve bonding and reduce process time, while also employing a stress relief edge structure and Ag paste sintering for enhanced reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electroless plating is used to form copper circuits on ceramic substrate, then circuit formation is achieved, but etching time increases and circuit spacing increases
Solution Approach 1:
The patent applies preliminary action by pre-forming metal patterns on the ceramic substrate surface before bonding the copper foil. This eliminates the need for subsequent etching of thick copper circuits, as the metal patterns serve as pre-defined circuit traces that guide copper bonding, thereby reducing etching time and avoiding circuit spacing issues
Solution Approach 2:
The patent inverts the conventional sequence by bonding copper foil to pre-formed metal patterns rather than forming copper circuits through etching and plating. This reversal eliminates the etching step entirely for circuit formation, solving both the time consumption and circuit spacing problems
2Temperature
If dual side cooling with spacer is used, then cooling capability is improved, but bonding force is reduced due to thermal expansion mismatch
Solution Approach 1:
The patent changes the material parameters of the spacer by selecting a material with thermal expansion coefficient and thermal conductivity matched to the ceramic substrate. This parameter matching eliminates thermal mismatch stress during bonding and operation, maintaining strong bonding force while enabling effective cooling
Solution Approach 2:
The patent uses a specially selected spacer as an intermediary component between the ceramic substrates. This mediator has thermally matched properties that allow it to bridge the substrates without introducing thermal stress, thus maintaining bonding strength while providing the required cooling function
3Device complexity
If conventional brazing method is used, then bonding process is simplified, but reliability is reduced due to thermal conductivity mismatch
Solution Approach 1:
The patent changes the thermal conductivity parameter of the spacer material to match the ceramic substrate. This thermal parameter matching ensures uniform heat distribution during brazing and operation, preventing thermal stress concentration and improving substrate reliability while maintaining process simplicity
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 shortens the overall process time, improves the bonding force and reliability of the ceramic substrate, and addresses issues related to electroless plating and thermal mismatch, resulting in a more reliable and efficient ceramic substrate production with improved thermal properties.
Implementation Method 1
preparing a metal substrate by etching a copper sheet
Implementation Method 2
preparing a unit ceramic substrate by etching a ceramic substrate
Implementation Method 3
assembling the metal substrates and the unit ceramic substrate such that the metal substrates are disposed on both surfaces of the unit ceramic substrate using a brazing jig
Implementation Method 4
sintering the metal paste
Implementation Method 5
brazing and bonding the spacer and the ceramic substrates
Data Source
AI summary
A ceramic substrate manufacturing method is provided in which a copper sheet is etched and then bonded to a ceramic substrate, so that the ceramic substrate has reduced to overall processing time and improved reliability and product lifespan. The ceramic substrate manufacturing method includes the steps of: etching a copper sheet so as to prepare a metal substrate; etching a ceramic substrate so as to prepare a unit ceramic substrate; assembling the metal substrate and the unit ceramic substrate; bonding the metal substrate and the unit ceramic substrate so as to form a stack; partially printing a metal paste on the surface of the stack; and sintering the metal paste.