AlSi Alloy Soldering Reliability Without Primary Si Particles
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Solution Overview
Problem
Conventional aluminum alloys used for soldering, particularly those with AlSi compositions, face issues with process reliability and material erosion due to large primary Si particles, which lead to local melting and hole formation in thin-walled components during the soldering process.
Innovation Solution
Producing an aluminum alloy with specific weight proportions of Si, P, B, Ti, Fe, Cu, Mn, Mg, Zn, and Cr, ensuring the absence of primary Si particles larger than 10 µm, and using a method that omits titanium borides for grain refinement, thereby preventing local Si excess and ensuring a reliable soldering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aluminum titanium boride (AlTiB) wires are used for grain refinement, then a fine structure is achieved, but primary Si particles larger than 10 µm are formed causing local melting and hole formation during soldering
Solution Approach 1:
The invention extracts and removes the harmful aluminum titanium boride (AlTiB) grain refiner from the alloy composition. By eliminating this specific additive, the patent prevents the formation of coarse primary Si particles that cause soldering defects, while maintaining acceptable grain structure through alternative means
Solution Approach 2:
The invention changes the chemical composition parameters by strictly limiting phosphorus to ≤10 ppm and boron to ≤10 ppm, while maintaining silicon content at 4.5-12 wt%. These parameter adjustments prevent the formation of coarse primary Si particles during solidification, resolving the contradiction between grain fineness and soldering reliability
2Loss of substance
If solder layer thickness is reduced to save material and avoid influencing core material properties, then material efficiency is improved, but the soldering process becomes less reliable and erosion/hole formation occurs
Solution Approach 1:
The invention converts the potentially harmful effect of silicon particles into a beneficial outcome by precisely controlling silicon content (4.5-12 wt%) and eliminating coarse primary Si particles through restricted phosphorus and boron levels. This allows thin solder layers to be used without the harmful local melting effect, transforming a material efficiency gain into a reliable process
3Stability of the object's composition
If primary Si particles are present in the aluminum alloy, then the alloy structure is formed, but local excess Si supply causes core material melting and erosion during soldering
Solution Approach 1:
The invention applies local quality control by specifically targeting and eliminating coarse primary Si particles (>10 µm) while maintaining the overall alloy composition and eutectic structure. Through restricted phosphorus (≤10 ppm) and boron (≤10 ppm) levels, the patent ensures uniform silicon distribution at the molecular level, preventing local excess Si supply that causes erosion during soldering
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 solution provides a process-reliable soldering process without material erosion, particularly effective for thin aluminum solder layers and core materials, ensuring consistent and reliable connections in complex components like heat exchangers.
Implementation Method 1
In the conventional production of AlSi aluminum alloys, primary aluminum is first melted together with silicon in a melting or casting furnace and other alloying elements are added
Data Source
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AI summary
An aluminum alloy contains (in weight%) silicon (4.5-12), phosphorus (10 ppm or less), boron (10 ppm or less), titanium (0.2 ppm or less, preferably 140-240 ppm), iron (0.8 or less), copper (0.3 or less), manganese (0.1 or less), magnesium (2 or less), zinc (0.2 or less), chromium (0.05 or less) and remainder of aluminum and unavoidable impurities, and is free of primary silicon particles having size of more than 10 mu m. Independent claims are included for the following: (1) aluminum alloy product; (2) bar; and (3) manufacture of aluminum alloy.