Metal-Ceramic Substrate Etching via Horizontal Positioning
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Solution Overview
Problem
Existing methods for structuring metal-ceramic substrates are inefficient, requiring long residence times in etching solutions and high energy consumption, with incomplete removal of active metals, particularly in the context of power electronics where rapid and resource-efficient processing is needed.
Innovation Solution
A method involving two metal-ceramic substrates with a bonding layer containing a high-melting-point metal and an active metal, using specific etching solutions to remove the metal layer and active metal separately, with optimized substrate positioning to enhance etching solution accessibility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching techniques are used with vertical stacking of substrates, then complete etching can be achieved, but the residence time in etching solutions is extended and productivity is reduced
Solution Approach 1:
The patent transitions from vertical stacking to horizontal arrangement of substrates in the etching solution. This dimensional change allows the etching solution to access all substrate surfaces simultaneously without shadowing effects, achieving complete etching while reducing residence time and improving productivity.
Solution Approach 2:
The patent separates the etching process into two distinct etching solutions: first etching solution for metal layer removal and second etching solution for active metal removal from the bonding layer. This segmentation enables optimized etching conditions for each material type, ensuring complete removal while reducing overall processing time.
2Productivity
If vertical stacking of substrates is used in etching, then space efficiency is improved, but etching solution accessibility is reduced leading to incomplete material removal
Solution Approach 1:
The patent arranges substrates horizontally in the etching solution rather than stacking them vertically. This allows the etching solution to flow freely around all substrate surfaces, ensuring complete material removal while maintaining space efficiency through optimized substrate positioning and spacing.
3Reliability
If high temperatures are used for direct copper bonding, then bonding reliability is improved, but energy consumption increases and process complexity increases
Solution Approach 1:
The patent changes the bonding temperature parameter from high temperatures (near copper melting point) to moderate temperatures (650-1000°C). This parameter change is achieved by using a solder containing active metals that react with ceramic at lower temperatures to form bonding layers, reducing energy consumption while maintaining bonding reliability.
Solution Approach 2:
The patent introduces a solder as an intermediary bonding material between metal foil and ceramic body. The solder contains active metals that react with ceramic to form reaction layers, enabling reliable bonding at lower temperatures without requiring direct copper-ceramic bonding at high temperatures.
4Reliability
If silver-containing solders are used for bonding, then bonding reliability is improved, but silver migration problems occur
Solution Approach 1:
The patent modifies the chemical composition parameters of the solder by reducing or eliminating silver content while adjusting the ratios of other metals (copper, bismuth, tin, indium). This parameter change maintains bonding reliability through optimized composition while preventing silver migration issues.
Solution Approach 2:
The patent replaces expensive silver-containing solder with silver-free or low-silver solder formulations. This substitution uses more economical materials (copper, bismuth, tin, indium) that achieve comparable bonding performance without the harmful silver migration effect, effectively replacing a problematic material with a superior alternative.
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 allows for rapid, complete, and resource-efficient removal of metal layers and active metals, reducing processing time and energy consumption while ensuring thorough material removal.
Implementation Method 1
During etching, the metal of the metal foil and the components of the bonding layer are then dissolved using a plurality of etching solutions and removed from the metal-ceramic substrate
Implementation Method 2
The active metal is subsequently dissolved and removed by treatment with a second etching solution
Implementation Method 3
The role of the active metal is to react with the ceramic material and thus to enable a bonding of the ceramic material to the remaining solder to form a reaction layer
Data Source
AI summary
The invention relates to a method for structuring metal-ceramic substrates and to a structured metal-ceramic substrate which can be used in particular in power electronics. In the method, a first metal-ceramic substrate and a second metal-ceramic substrate are etched, wherein, while being contacted with an etching solution that is capable of removing active metal from the bonding layer of the metal-ceramic substrates, the first metal-ceramic substrate and the second metal-ceramic substrate are positioned such that an orthogonal projection of the first metal-ceramic substrate onto a projection plane parallel to the metal layer of the first metal-ceramic substrate shades no more than 60% of the metal layer of the second metal-ceramic substrate.