Silver-Copper Brazing Material for Heat Dissipation Base
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Solution Overview
Problem
The increasing integration density of circuits in electronic devices leads to issues with silver-copper based brazing materials protruding from joint regions, causing short circuits between adjacent metal circuit plates on ceramic substrates.
Innovation Solution
A brazing material comprising silver, copper, indium, zinc, or tin, titanium, zirconium, hafnium, niobium, molybdenum, osmium, rhenium, or tungsten, which provides good wettability, reduces gaps, and prevents excessive viscosity to prevent protrusion from joint regions, ensuring high joining strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the interval between metal circuit plates is narrowed to increase integration density, then circuit integration degree is improved, but brazing material protrudes from joint regions causing short circuits
Solution Approach 1:
The patent changes the chemical composition parameters of the brazing material by adding specific elements (Ti, Zr, Hf, Nb) to modify its physical properties. This enables the brazing material to have controlled viscosity and wetting characteristics that prevent protrusion while maintaining effective joining, thus allowing narrower intervals between circuit plates without causing short circuits.
Solution Approach 2:
The patent creates a composite brazing material by combining silver-copper base metal with reactive metal elements (Ti, Zr, Hf, Nb) and carbon powder. This composite composition provides both the necessary joining strength and controlled flow characteristics that prevent excessive protrusion into narrow gaps between circuit plates, resolving the contradiction between integration density and short circuit prevention.
2Stability of the object's composition
If carbon powder and active metals are added to silver-copper based brazing material, then thermal cycle resistance is improved, but brazing material protrudes from joint regions
Solution Approach 1:
The patent optimizes the concentration parameters of carbon powder and active metals within specific ranges (Ti: 0.1-5 wt%, Zr: 0.1-5 wt%, Hf: 0.1-5 wt%, Nb: 0.1-5 wt%, C: 0.01-3 wt%). This controlled composition achieves adequate thermal cycle resistance while limiting excessive reactivity and protrusion, balancing stability improvement with shape control.
Solution Approach 2:
The patent creates local quality differences within the brazing material by incorporating carbon powder and reactive metals that concentrate at specific locations during brazing. The carbon powder provides thermal stability at the joint interface, while the reactive metals create localized bonding zones, enabling thermal cycle resistance without uniform protrusion throughout the joint region.
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 brazing material effectively prevents short circuits by maintaining a low viscosity and reducing gaps between joining layers, enhancing the thermal cycle resistance and reliability of the heat dissipation base, while maintaining high joining strength between circuit members and substrates.
Implementation Method 1
the brazing material contains the element A, which is low in melting point, thereby reducing gaps between individual joining layers made of the brazing material
Data Source
AI summary
A brazing material includes silver and copper as main components; at least one element A selected from indium, zinc, and tin; at least one element B selected from titanium, zirconium, hafnium, and niobium; and at least one element C selected from molybdenum, osmium, rhenium, and tungsten. The content of copper is not less than 35% by mass and not more than 50% by mass, based on the total amount of silver, copper, and the elements A, B and C. A heat dissipation base includes a supporting substrate, circuit members on a first main surface of the substrate, and a heat dissipation member on a second main surface opposite to the first main surface. The circuit members are joined to the supporting substrate by a joining layer composed of the brazing material.