Ceramic Via Substrate with Active Metal Paste for Stable Conductivity
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Solution Overview
Problem
Existing ceramic substrates face challenges in achieving high reliability due to the use of via materials with eutectic regions of silver and copper, which affect electrical connectivity and thermal stability.
Innovation Solution
A method involving a first metal paste with specific metal powder and active metal powder is used, fired at a controlled temperature below the metal powder's melting point, forming a dispersed metal body with a reaction layer, enhancing electrical and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a through conductor containing silver and copper as main components is used, then electrical conductivity is improved, but thermal stability deteriorates due to eutectic region formation
Solution Approach 1:
The via material is segmented into multiple metal layers with different compositions. The first metal layer contains silver and copper in a non-eutectic ratio (e.g., Ag 70-90 wt%, Cu 10-30 wt%), while the second metal layer contains a different metal composition. This segmentation prevents the formation of a continuous eutectic region, thereby maintaining thermal stability while preserving electrical conductivity through the layered structure.
Solution Approach 2:
The invention uses a composite via material structure consisting of multiple metal layers with different compositions. The first metal layer (Ag-Cu non-eutectic) and second metal layer (different composition) are combined to create a composite material that simultaneously achieves good electrical conductivity and thermal stability, eliminating the trade-off between these properties.
2Ease of manufacture
If a via material with eutectic region of silver and copper is used, then manufacturing process is simplified, but electrical connectivity and thermal stability deteriorate
Solution Approach 1:
The via material is prepared in advance with a predetermined layered structure where the first metal layer (Ag-Cu non-eutectic) and second metal layer are already configured in specific proportions before insertion. This preliminary preparation ensures that the non-eutectic composition is maintained during the firing process, preventing eutectic region formation and ensuring reliable electrical connectivity without complicating the manufacturing process.
3Manufacturing precision
If firing temperature is increased to improve ceramic sintering, then ceramic density is improved, but metal powder melts and disperses improperly
Solution Approach 1:
The invention changes the compositional parameters of the metal powder to have a higher melting point than the ceramic firing temperature. By selecting metal powders with melting points above the firing temperature range, the metal maintains its integrity and proper dispersion during high-temperature sintering, achieving both good ceramic density and proper metal distribution without melting.
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 resulting ceramic sintered body substrate achieves high reliability with stable electrical connections and improved thermal conductivity, ensuring consistent performance in light-emitting devices.
Implementation Method 1
a covering metal member having a melting point lower than a melting point of the metal powder and covering at least a part of the metal powder
Implementation Method 2
a reaction layer of the metal compound on an inner wall of the through hole
Implementation Method 3
a reactant of the metal compound on a grain boundary of the metal powder
Data Source
AI summary
A method for manufacturing a ceramic sintered body substrate includes preparing a ceramic substrate 1 provided with a through hole 2 before firing (S11), disposing a first metal paste 3 in the through hole (S12), and firing the ceramic substrate provided with the first metal paste (S14). In the disposing of the first metal paste, the first metal paste includes a plurality of particles of first metal powder (4) and a plurality of particles of active metal powder (50), and the first metal powder includes a metal powder (4a) serving as a core, and a covering metal member (40b) having a melting point lower than a melting point of the metal powder and covering at least a part of the metal powder, and in the firing of the ceramic substrate, a firing temperature is a temperature in a range from 700° C. to less than the melting point of the metal powder.