Silver-Sintered DBC Substrates to Prevent Voids and Cracks
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Solution Overview
Problem
Traditional high-temperature bonding processes for direct bonded copper (DBC) substrates often result in internal defects such as ceramic-copper interfacial voids and cracks, which are unacceptable for high-performance power modules.
Innovation Solution
The method involves sinter bonding leadframes to a ceramic tile using a sinter material layer at low temperatures (less than 500°C) and pressures (less than 100 MPa), avoiding the defects associated with high-temperature cladding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature cladding process is used to bond copper to ceramic tile, then bonding strength is achieved, but internal defects such as voids and cracks occur
Solution Approach 1:
The patent changes the bonding parameters from high-temperature cladding to low-temperature sintering process. By using sintering at temperatures below 500°C with controlled pressure and atmosphere, the method achieves reliable bonding between copper leadframes and ceramic tiles while avoiding the thermal stress and rapid heating that cause voids and cracks in traditional high-temperature processes
Solution Approach 2:
The patent introduces a sintering precursor material layer as an intermediary between the copper leadframe and ceramic tile. This intermediate layer facilitates bonding at lower temperatures through sintering mechanisms, preventing direct high-temperature contact that would cause thermal shock and internal defects in the ceramic-copper interface
2Ease of manufacture
If traditional high-temperature bonding process is used, then manufacturing experience is available, but defect formation occurs
Solution Approach 1:
The patent fundamentally changes the manufacturing parameters from conventional high-temperature cladding to low-temperature sintering. This parameter change enables precise control over the bonding process, achieving defect-free interfaces while maintaining manufacturability through established sintering techniques and controlled atmospheric processing
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 approach enables the fabrication of DBC substrates with improved integrity and reliability, reducing the occurrence of defects like voids and cracks, and allowing for the use in high-power devices like IGBTs and FRDs without compromising thermal conductivity.
Implementation Method 1
sinter bonding the first leadframe and the second leadframe to the ceramic tile to form a sinter bonded DBC substrate includes applying a sintering heat treatment to the precursor assembly at a temperature that is less than 500° C. and a pressure that is less than 100 MPa
Data Source
AI summary
A method includes applying a sintering precursor material layer to each of a first surface and a second surface of a ceramic tile, and assembling a precursor assembly of a direct bonded copper (DBC) substrate by coupling a first leadframe on the sinter precursor material layer on the first surface of the ceramic tile and a second leadframe on the second surface of the sinter precursor material layer on a second surface of the ceramic tile such that the ceramic tile is disposed between the first leadframe and the second leadframe. The method further includes sinter bonding the first leadframe and the second leadframe to the ceramic tile to form a sinter bonded DBC substrate.