Wiring Substrate With Multi-Layer Through Hole Filling
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Solution Overview
Problem
Existing wiring substrates face challenges in achieving suitable thickness of wiring layers while filling through holes, particularly when the aspect ratio of the through holes is large, leading to excessively thick wiring layers.
Innovation Solution
The wiring substrate design includes a core layer with through holes that are filled using a multi-layer metal structure, where the second metal layer forms an X-shape inside the hole, with recess portions filled by third and fourth metal layers, allowing for independent control of wiring layer thickness through additional metal layers formed on these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the through hole is filled to suitably fill the hole, then the through hole filling is improved, but the wiring layer thickness becomes excessively thick
Solution Approach 1:
The patent segments the metal layer formation process into multiple distinct layers (first metal layer formed on inner wall, second metal layer filling the hole, third and fourth metal layers in recess portions, and fifth and sixth metal layers formed on top). This segmentation allows independent control of each layer's thickness and function, enabling suitable through hole filling while preventing excessive overall wiring layer thickness.
Solution Approach 2:
The patent applies different metal layers with potentially different properties to different locations within the through hole structure. The first metal layer lines the inner wall, the second metal layer fills the central portion, and the third and fourth metal layers specifically fill the recess portions. This local differentiation enables precise control over where material is deposited and how thick each region becomes.
2Ease of operation
If a multi-layer metal structure is used to control wiring layer thickness, then the wiring layer thickness control is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges multiple metal layer formation steps into a unified through hole filling structure. The first metal layer on the inner wall, the second metal layer filling the hole, and the third and fourth metal layers in the recess portions work together as an integrated system. This merging allows the complex multi-layer structure to function as a cohesive solution for thickness control rather than as separate independent components.
Solution Approach 2:
The patent introduces vertical layering (another dimension) to control wiring layer thickness. Instead of controlling thickness through a single-layer horizontal approach, the invention uses multiple stacked metal layers (first, second, third, fourth, fifth, and sixth layers) where each layer contributes to the overall thickness control. This dimensional approach enables precise thickness management while distributing the complexity across multiple manageable layers.
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
This approach enables the formation of wiring layers with suitable thicknesses while effectively filling through holes, improving the manufacturing process by allowing for precise control over the thickness of the wiring layers.
Implementation Method 1
a first metal layer that is formed on an inner wall face of the through hole and formed on or above the first and second faces
Implementation Method 2
a first metal layer that is formed on an inner wall face of the through hole and formed on or above the first and second faces
Implementation Method 3
a second metal layer that is formed on the first metal layer and fills the through hole
Implementation Method 4
a third metal layer that is provided in the first recess portion; a fourth metal layer that is provided in the second recess portion
Data Source
AI summary
A wiring substrate includes: a core layer having a first face, and a second face opposite to the first face; a through hole that penetrates the core layer; a first metal layer formed on an inner wall face of the through hole and formed on or above the first and second faces; a second metal layer that is formed on the first metal layer and fills the through hole, wherein the second metal layer has a first recess portion opposed to the through hole, and a second recess portion opposed to the first recess portion via the through hole; a third metal layer provided in the first recess portion; a fourth metal layer provided in the second recess portion; a fifth metal layer formed on the second metal layer and the third metal layer; and a sixth metal layer formed on the second metal layer and the fourth metal layer.