Method for producing a metal-ceramic substrate
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Solution Overview
Problem
Existing methods for producing metal-ceramic substrates, such as direct copper bonding and solder-based techniques, face limitations in temperature requirements and material compatibility, and struggle to enhance thermal and current conductivity without altering the composition of the bonding layer.
Innovation Solution
A method involving a stack of ceramic bodies, metal foils, and solder materials with specific metal components (high and low melting points, and active metals) is used, where the stack is heated under controlled conditions to form a material bond, optimizing the thermal and current conductivity without silver migration and maintaining the bonding layer composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder-based techniques are used to connect metal foils to ceramic bodies, then thermal and current conductivity can be improved, but the composition of the bonding layer must be altered which increases complexity and cost
Solution Approach 1:
The patent extracts the harmful element (silver) from the solder material composition to prevent silver migration while maintaining the bonding layer's essential function. By removing silver and using alternative metal combinations (copper, zinc, tin, bismuth), the solution improves reliability without requiring complex multi-component bonding layers.
Solution Approach 2:
The patent changes the material parameters of the solder by replacing silver-based compositions with silver-free alternatives. This parameter change maintains the bonding layer's conductivity function while eliminating silver migration issues, thus improving reliability without increasing compositional complexity.
2Strength
If high temperatures are used for direct copper bonding, then stable material connection is achieved, but the temperature requirements become stringent limiting applicability
Solution Approach 1:
The patent changes the temperature parameter by using solder materials with lower melting points (copper-zinc-tin-bismuth system) compared to direct copper bonding. This allows achieving stable material connection at lower temperatures, thus maintaining bond strength while reducing temperature stringency and expanding applicability.
3Reliability
If silver-containing solders are used to improve conductivity, then thermal and current conductivity increase, but silver migration problems occur
Solution Approach 1:
The patent extracts the harmful silver component from the solder material to eliminate silver migration. The remaining metal combination (copper, zinc, tin, bismuth) maintains adequate electrical and thermal conductivity while being free from migration issues, thus improving reliability without generating harmful migration effects.
4Reliability
If the bonding layer composition is modified to enhance conductivity, then performance improves, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent changes the compositional parameters to use common, cost-effective metals (copper, zinc, tin, bismuth) rather than expensive silver. This parameter change maintains improved conductivity performance while reducing manufacturing cost and simplifying production, thus improving reliability while enhancing ease of manufacture.
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 improves thermal and current conductivity of metal-ceramic substrates by controlling heating durations and temperatures, reducing silver migration, and maintaining the bonding layer composition, resulting in enhanced performance and cost-effectiveness.
Implementation Method 1
the copper compound melts and wets the surface of the ceramic body so that a stable material connection occurs
Implementation Method 2
the copper compound melts and wets the surface of the ceramic body
Implementation Method 3
The role of the active metal is to react with the ceramic material, and thus to enable a connection of the ceramic material with the remaining solder to form a reaction layer
Implementation Method 4
heating the stack, wherein at least one of the following conditions is satisfied: b1) the high temperature heating duration is no more than 60 min
Data Source
AI summary
The present invention relates to a method for producing a metal-ceramic substrate. The method has the following steps: providing a stack containing a ceramic body, a metal foil, and a solder material in contact with the ceramic body and the metal foil, wherein the solder material has: a metal having a melting point of at least 700° C., a metal having a melting point of less than 700° C., and an active metal; and heating the stack, wherein at least one of the following conditions is satisfied: the high temperature heating duration is no more than 60 min; the peak temperature heating duration is no more than 30 min; the heating duration is no more than 60 min.