Through-Via Substrate Plating Structure for Void-Free Filling
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Solution Overview
Problem
Through-via substrates often suffer from void formation during the plating process, leading to electrical resistance issues due to inadequate control of plating growth within the through holes.
Innovation Solution
A through-via substrate design featuring a seed layer and two plated portions with a controlled interface, where the second plated portion grows from the interface towards the second surface, reducing void formation by optimizing the plating process with specific material compositions and dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filled via is formed by a plating process, then electrical resistance is reduced, but voids are formed inside the through hole
Solution Approach 1:
The through via is divided into three distinct segments: a seed layer portion, a first plated portion, and a second plated portion. This segmentation allows each layer to be formed with different plating conditions and material compositions, enabling precise control over the filling process to eliminate voids while maintaining low electrical resistance.
Solution Approach 2:
Different portions of the through via have different material compositions and properties. The seed layer portion provides nucleation sites, the first plated portion has specific material properties optimized for adhesion and conductivity, and the second plated portion is optimized for filling completeness. This local differentiation ensures both low resistance and void-free structure.
2Manufacturing precision
If the speed of growth of plating inside a through hole is not adequately controlled, then voids are formed, but controlling the growth speed increases process complexity
Solution Approach 1:
The plating process is segmented into two distinct plating processes: a first plating process that forms the seed layer and first plated portion, and a second plating process that forms the second plated portion. Each process uses different plating solutions and conditions, allowing independent optimization of growth speed control for each segment without increasing overall process complexity.
Solution Approach 2:
The plating process parameters are changed between the first and second plating processes. The first plating solution has specific composition and conditions optimized for initial filling, while the second plating solution has different parameters optimized for completing the fill. This parameter differentiation enables precise growth control at each stage.
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 reduces voids in through vias, enhancing electrical conductivity and reliability by controlling the growth of the plated portions, thereby improving the substrate's performance.
Implementation Method 1
a seed layer located on the wall surface, the seed layer spreading along the wall surface from the first surface toward the second surface
Implementation Method 2
A filled via contains a conducting material such as copper charged into a through hole. In a case where a filled via is formed by a plating process
Data Source
AI summary
A through-via substrate includes a substrate and a through via. The substrate includes a first surface and a second surface located on a side opposite to the first surface. The substrate is provided with a through hole including a wall surface extending from the first surface to the second surface. The through via is located in the through hole. The through via extends from the first surface to the second surface. The through via includes a seed layer, a first portion, and a second portion. The seed layer is located on the wall surface. The seed layer spreads along the wall surface from the first surface toward the second surface. The first portion covers the seed layer. The second portion touches the first portion at an interface traversing the through hole.