Wiring Substrate Trench Plating for Void-Free Conductive Layers
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Solution Overview
Problem
Existing wiring substrates face defects such as seams and voids in conductive layers due to plating film growth from multiple directions, particularly in high-aspect-ratio trenches and through-holes, leading to thermal stress-induced disconnection and reliability issues with external connection terminals.
Innovation Solution
The wiring substrate configuration includes a substrate body with trenches and through-holes, where the first conductive layer is filled to prevent projection from the trench inner bottom surface, and the second and third conductive layers are formed with the second conductive layer interposed between them, ensuring plating films grow from a single direction to prevent defects, and the use of a titanium-copper stacked configuration for improved adhesiveness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plating film is grown from multiple directions to fill high-aspect-ratio trenches and through-holes, then the conductive layers can be formed, but seams and voids occur leading to thermal stress-induced disconnection
Solution Approach 1:
The conductive layer formation is divided into multiple sequential steps: first forming a bottom conductive layer, then forming side conductive layers on the inner side surfaces of trenches and through-holes. This segmentation allows each layer to be formed without defects while maintaining overall structural integrity
Solution Approach 2:
A bottom conductive layer is formed in advance at the bottom surface of trenches and through-holes before forming the side conductive layers. This preliminary action provides a foundation that prevents void formation and ensures reliable electrical connection throughout the high-aspect-ratio structures
2Ease of manufacture
If conventional plating methods are used to form conductive layers in trenches and through-holes, then conductive paths are created, but defects such as seams and voids reduce connecting reliability with external terminals
Solution Approach 1:
The conductive layer is segmented into bottom conductive layer and side conductive layer components, each formed through separate plating processes. This ensures that each segment is defect-free while collectively providing reliable electrical connection to external terminals
Solution Approach 2:
Different regions of the conductive structure have specialized functions: the bottom conductive layer provides foundational electrical connection and void prevention, while the side conductive layers provide lateral electrical pathways. This local quality optimization ensures reliable terminal connections throughout the structure
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 configuration effectively prevents seams and voids in the conductive layers, enhancing the reliability of connections by reducing thermal stress and maintaining adhesiveness between layers, thereby improving the connecting reliability with external terminals.
Implementation Method 1
a first conductive layer having a first surface toward the trench and being filled inside at least a portion of the through-hole from the second end
Implementation Method 2
ensuring plating films grow from a single direction to prevent defects
Implementation Method 3
the use of a titanium-copper stacked configuration for improved adhesiveness and reliability
Data Source
AI summary
A wiring substrate includes a substrate body including a first substrate surface and a second substrate surface, a trench being open toward the first substrate surface, the trench having an inner bottom surface and an inner side surface, a through-hole having a first end communicating with the inner bottom surface of the trench and a second end being open toward the second substrate surface, a first conductive layer having a first surface toward the trench and being filled inside at least a portion of the through-hole from the second end, a second conductive layer covering the first surface and at least a part of the inner bottom surface of the trench, and a third conductive layer covering the second conductive layer and being filled inside the trench.