Gold-Tin Alloy Electroplating Uniformity Control
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Solution Overview
Problem
Existing methods for electroplating gold-tin alloys on large panels result in non-uniform composition, leading to inconsistent mechanical and electrical properties, and often render entire assemblies unusable due to variations in eutectic melting points and poor soldering quality.
Innovation Solution
A method and system involving a masked panel with a predetermined pattern of conductive material applied to control the electrical current distribution, ensuring uniform deposition of gold-tin alloy across the panel by selectively applying electrical current to induce a uniform gold:tin ratio in the electroplating solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electroplating is used on large panels, then productivity is improved by processing large areas, but composition uniformity deteriorates due to uneven deposition
Solution Approach 1:
The patent applies a predetermined pattern of conductive material to different regions of the panel to create localized electrical properties. This allows each region to receive appropriate current density, ensuring uniform alloy composition deposition across the entire large panel while maintaining high productivity
Solution Approach 2:
The patent modifies the electrical parameters by applying a predetermined pattern of conductive material that changes the current distribution across the panel. This parameter change enables control over deposition rates of different metals, achieving uniform composition even on large panels
2Area of stationary object
If conventional electroplating is used on large panels, then processing large areas is achieved, but deposition uniformity deteriorates due to varying electrical fields
Solution Approach 1:
The predetermined pattern of conductive material creates localized electrical characteristics across different regions of the large panel. This ensures that each area experiences appropriate current density, achieving uniform deposition across the entire large area
Solution Approach 2:
The conductive material pattern is designed to create equipotential regions that equalize the electrical field distribution across the large panel. This eliminates varying electrical fields that cause non-uniform deposition, enabling consistent alloy composition across the entire panel area
3Speed
If tin is deposited more quickly due to uneven electrical charge, then deposition speed is improved, but alloy composition uniformity deteriorates
Solution Approach 1:
The predetermined pattern of conductive material creates localized electrical properties that control the deposition rate of different metals in different regions. This balances the deposition speeds of gold and tin, ensuring uniform alloy composition while maintaining overall deposition efficiency
Solution Approach 2:
The patent changes the electrical parameters by applying conductive material in a predetermined pattern, which modifies the current density distribution. This parameter change controls the relative deposition rates of different metals, achieving uniform alloy composition
4Stability of the object's composition
If eutectic melting point varies across the panel, then melting point variation is reduced, but requires controlled composition deposition
Solution Approach 1:
The predetermined pattern of conductive material creates localized electrical properties that ensure uniform alloy composition deposition. This maintains consistent eutectic melting point across the panel, improving composition stability
Solution Approach 2:
The conductive material is applied in a predetermined pattern before electroplating begins. This preliminary action pre-configures the electrical field distribution to ensure uniform composition and consistent eutectic melting point throughout the deposition process
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
Achieves a substantially uniform gold-tin alloy composition across the majority of the panel, improving soldering quality and reducing production costs by maintaining a consistent eutectic melting point, thus enhancing the reliability and performance of electroplated products.
Implementation Method 1
electrical current is applied to the masked panel. The electrical current is conducted across the planar surface via the conductive material to induce a predetermined electrical current distribution across the planar surface and thereby pull gold ions and tin ions from the electroplating solution. The pulled gold and tin ions are deposited upon a supermajority of an unmasked area of the masked panel
Data Source
AI summary
A method of controlling alloy composition of deposited gold-tin alloy during electroplating of a large panel includes masking at least one planar surface of the panel with conductive material applied in a predetermined pattern. The masked panel is located at least partially within an electroplating solution including a gold-tin alloy in solution at a predetermined gold:tin ratio. Electrical current applied to the masked panel is conducted across the planar surface via the conductive material to induce a predetermined electrical current distribution across the planar surface and thereby pull gold ions and tin ions from the electroplating solution. The pulled ions are deposited upon a supermajority of an unmasked area of the masked panel. The predetermined pattern is selected to achieve deposition of the gold-tin alloy with substantially uniform alloy composition, directly corresponding to the predetermined gold:tin ratio, across the supermajority of the unmasked area of the masked panel.