Metal-Ceramic Substrate Contact Area for Thermal Shock Resistance
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Solution Overview
Problem
Metal-ceramic substrates in power electronics suffer from reduced thermal shock resistance due to detachment of the metal layer from the ceramic body under temperature fluctuations, primarily because of differing thermal expansion coefficients.
Innovation Solution
A metal-ceramic substrate design with a structuring region in the metal layer that includes both solid and non-solid materials, where the ratio of solid material to total length exceeds 60%, defined by specific geometric criteria, enhances thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal layer is bonded to the ceramic body using conventional methods (DCB or soldering), then the metal layer can be reliably attached to the ceramic body, but the substrate suffers from reduced thermal shock resistance due to detachment under temperature fluctuations
Solution Approach 1:
The metal layer is segmented into multiple regions with different solid material proportions. The structuring region (within 80-150 μm of the interface) contains partially solid and partially non-solid material with a solid material proportion of 60-90%, while other regions have different compositions. This segmentation allows different zones to fulfill different functions: the structuring region provides thermal shock resistance while maintaining bonding reliability.
Solution Approach 2:
The patent applies local quality by creating a specific compositional gradient in the metal layer. The structuring region near the ceramic interface has a controlled proportion of solid material (60-90%) that differs from other regions. This localized compositional variation optimizes thermal shock resistance at the critical interface zone while maintaining overall bonding reliability.
2Strength
If the metal layer is fully solid to ensure strong bonding, then bonding strength is maximized, but thermal shock resistance decreases due to stress from thermal expansion differences
Solution Approach 1:
The patent changes the compositional parameter of the metal layer by controlling the proportion of solid material in the structuring region to be between 60-90%. This parameter optimization balances bonding strength and thermal shock resistance. The non-solid material proportion of 10-40% in this region reduces thermal expansion stress while maintaining sufficient bonding strength through the solid material network.
3Stability of the object's composition
If the metal layer contains non-solid material to improve thermal shock resistance, then thermal shock resistance increases, but bonding reliability may be compromised
Solution Approach 1:
The metal layer is designed as a composite material system combining solid metal phases with non-solid material (such as glass frit or ceramic particles). This composite structure in the structuring region provides both thermal shock resistance through the non-solid component and bonding reliability through the solid material network that maintains cohesive attachment to the ceramic body.
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 designed substrate exhibits improved thermal shock resistance by maintaining a high proportion of solid material near the ceramic body interface, preventing detachment and enhancing durability under temperature variations.
Implementation Method 1
a copper foil is provided superficially with a copper compound (usually copper oxide), which has a lower melting point than copper, by reacting copper with a reactive gas (usually oxygen)
Implementation Method 2
When the copper foil treated in this way is applied to a ceramic body and the composite is heated, the copper compound melts and wets the surface of the ceramic body
Implementation Method 3
the copper compound melts and wets the surface of the ceramic body, so that a stable cohesive bond is created
Implementation Method 4
The role of the active metal is to react with the ceramic material and to thus facilitate a bonding of the ceramic material to the remaining solder, forming a reaction layer
Implementation Method 5
Due to the different thermal expansion coefficients of the metal and the ceramic, repeated temperature changes can lead to the metal layer detaching from the ceramic body
Data Source
AI summary
The invention relates to a metal-ceramic substrate, to an electronic component comprising a metal-ceramic substrate, and to a method for producing a metal-ceramic substrate. The metal-ceramic substrate comprises: a) a ceramic body which has a main extension plane, b) a metal layer which is connected to the ceramic body in a planar manner, the metal layer having a structuring region which comprises (i) partially solid material and (ii) partially non-solid material, and c) a contact area which is arranged on the metal layer and comprises silver, the structuring region having a geometry in a cross-section through the metal-ceramic substrate perpendicular to the main extension plane, the following requirement being met: S(BCsolid)/S(BCtotal)>60%, wherein: S(BCtotal) represents the total length of the line between points B and C, and S(BCsolid) represents the length of the line between points B and C that intersects the solid material.