Active Solder Paste for Low-Silver Copper-Clad Ceramic Bonding
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Solution Overview
Problem
Existing technologies for cladding ceramic with copper, such as DBC and AMB, face challenges including low reliability, high silver content in solders leading to high costs, complex and uncontrollable melting processes, and susceptibility to oxidation, resulting in welding defects and segregation.
Innovation Solution
The development of an active solder paste composition comprising 1-20 wt% titanium hydride and 75-94 wt% copper-phosphorus-silver alloy powders, along with a flux, which reduces silver content, lowers welding temperature, and enhances the connection strength between titanium and copper, thereby improving welding strength and preventing segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional silver-copper-titanium alloy solder is used, then welding strength is achieved, but silver content is high (50-90 wt% Ag) leading to high cost
Solution Approach 1:
The patent changes the compositional parameters of the solder alloy by reducing silver content from 50-90 wt% to 3-10 wt% and introducing phosphorus (4-10 wt%) and titanium hydride (1-20 wt%), thereby achieving cost reduction while maintaining welding strength through new chemical interactions
Solution Approach 2:
The patent creates a composite solder system combining copper-phosphorus-silver alloy with titanium hydride powder, where the composite structure enables synergistic effects: phosphorus activates ceramic surface, titanium enhances bonding, and reduced silver content lowers cost while maintaining strength
2Reliability
If traditional silver-copper-titanium alloy solder is used, then welding is achieved, but melting process is complex and uncontrollable due to multiple intermetallic compounds forming
Solution Approach 1:
The patent extracts titanium from the traditional AgCuTi alloy matrix and presents it as separate titanium hydride powder additive, allowing controlled reaction with ceramic surface without forming complex intermetallic compounds during melting, thereby simplifying the melting process
Solution Approach 2:
The patent uses titanium hydride that pre-reacts with ceramic surface before melting occurs, forming a stable interface layer in advance. This preliminary action prevents complex intermetallic formation during the melting process, making the process more controllable and reliable
3Reliability
If traditional silver-copper-titanium alloy solder is used, then welding is achieved, but titanium is susceptible to oxidization causing decreased activity and affecting welding performance
Solution Approach 1:
The patent applies titanium hydride that reacts with ceramic surface before oxidation can occur during storage or handling. The hydride form provides preliminary protection, and the reaction with ceramic happens in situ, preventing titanium oxidization that would decrease activity and welding performance
4Strength
If traditional silver-copper-titanium alloy solder is used, then welding is achieved, but intermetallic compounds aggregate and segregate leading to material segregation
Solution Approach 1:
The patent extracts titanium from the alloy matrix and presents it as separate titanium hydride powder, preventing the formation of aggregating intermetallic compounds. The titanium reacts controllably with ceramic surface rather than forming segregated phases, maintaining composition homogeneity while achieving strong connection
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 proposed solution achieves a high welding strength, a flat and dense welded face, and reduced material segregation, while also lowering the solder cost and improving the reliability of the copper-clad ceramic substrates.
Implementation Method 1
a first metal powder and a second metal powder. The first metal powder contains titanium hydride... the connection strength of Ti and Cu is further enhanced
Implementation Method 2
the melting process of the silver-copper-titanium ternary alloy is complex and uncontrollable... the welding temperature is improved
Data Source
AI summary
Active solder paste compositions for cladding ceramic with copper, methods for cladding ceramic with copper, and copper-clad ceramic materials. Active solder paste compositions comprise, on the basis of the total weight of the active solder paste composition, 1-20 wt % of a first metal powder and 75-94 wt % of a second metal powder, with the balance being a flux, wherein the first metal powder contains titanium hydride and the second metal powder contains a copper-phosphorus-silver alloy. The active solder paste compositions can not only decrease the silver content, but can also reduce the welding temperature. Moreover, the connection strength of Ti and Cu is further enhanced, and the welding strength is improved, such that the material is less prone to segregation.