Semiconductor Heat Dissipation Base Plate Grain Refinement
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Solution Overview
Problem
The formation of coarse columnar crystal structures during the molten metal bonding process in semiconductor-mounting heat dissipation base plates leads to distorted fastening holes, reduced contact area, and adverse effects on heat dissipation and bonding, resulting in creep deformation and loose fastening due to varying crystal orientations.
Innovation Solution
Incorporating a crystal grain size reducing material, such as titanium-aluminum alloys or carbides, during the casting process to regulate grain diameters and prevent the formation of columnar crystals, ensuring equiaxial crystal structures with controlled grain sizes, thereby stabilizing fastening and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure aluminum is used for forming the metal circuit layer and heat dissipation base, then electrical conductivity and thermal conductivity are improved, but coarse columnar crystal structures form during solidification causing distorted fastening holes and reduced fastening reliability
Solution Approach 1:
The invention changes the chemical composition parameters of the aluminum alloy by adding specific elements (Ti: 0.01-0.1 wt%, B: 0.003-0.03 wt%, Si: 0.01-0.1 wt%) to control the crystal grain structure during solidification, thereby preventing coarse columnar crystal formation while maintaining electrical and thermal conductivity
Solution Approach 2:
The invention introduces intermediary substances (Ti and B elements) that act as grain refiners during solidification. These elements form intermediate compounds that disrupt the growth of columnar crystals and promote equiaxed fine grain structures, improving both fastening hole precision and overall reliability
2Ease of manufacture
If directional solidification cooling is used during molten metal bonding, then the bonding process is simplified, but coarse columnar crystal structures form exceeding 2 to 3 cm which adversely affect fastening and heat dissipation
Solution Approach 1:
The invention changes the compositional parameters by adding Ti and B elements that fundamentally alter the solidification behavior, transforming the crystal growth pattern from directional columnar to equiaxed fine grains, thereby eliminating the adverse effects while maintaining process simplicity
Solution Approach 2:
The invention applies local quality modification by introducing specific alloying elements that locally affect the solidification front, creating fine equiaxed grains in the regions where fastening holes will be formed, while the overall bonding process remains unchanged
3Manufacturing precision
If crystal grain boundaries are present across fastening holes, then the hole shape becomes distorted due to varying resistance against processing load, but reducing crystal grain size requires additional processing steps
Solution Approach 1:
The invention performs preliminary action by controlling the crystal grain structure during the initial casting process itself. The alloying elements Ti and B are added before solidification to pre-form fine equiaxed grains, eliminating the need for subsequent grain refinement processing steps
Solution Approach 2:
The invention changes the compositional parameters of the aluminum alloy to inherently produce fine-grained structures during solidification, thereby achieving high fastening hole accuracy without adding complex post-processing steps
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 effectively inhibits the generation of columnar crystal structures, ensuring stable fastening, preventing creep deformation, and maintaining consistent contact area, thus enhancing the reliability and heat dissipation performance of the semiconductor-mounting heat dissipation base plates.
Implementation Method 1
a crystal grain diameter regulated region in which crystal grain diameter is regulated is provided in at least a part of a surface of the heat dissipation base or the metal circuit layer
Data Source
AI summary
In a semiconductor-mounting heat dissipation base plate including: an insulating substrate to which a metal circuit layer for mounting a semiconductor chip thereon is fixed; a heat dissipation base formed from the same metal material as the metal circuit layer at a side opposite to the metal circuit layer across the insulating substrate and fixed to the insulating substrate similar to the metal circuit layer; and a strengthening member provided in the heat dissipation base so as to be separated from the insulating substrate, the sizes of crystal grains of a metal structure at a part of the heat dissipation base or the metal circuit layer are reduced by a crystal size reducing material adhered to a mold, thereby preventing an adverse effect of a columnar crystal structure.