Segmented Via Structure for Plating Void Prevention
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Solution Overview
Problem
Conventional circuit boards face issues with void formation and plating clogging during the via plating process, leading to defects such as open defects due to stress and low physical rigidity, especially in high temperature and high humidity environments.
Innovation Solution
A circuit board design featuring a via structure with multiple inflection portions and varying glass fiber content regions, where the via hole has a unique shape with increasing and decreasing widths, and a central region with a greater width than the upper and lower regions, and a manufacturing method involving laser processing to form the via hole with different glass fiber content regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional via structure with constant width is used, then the manufacturing process is simple, but plating clogging and void formation occur leading to open defects
Solution Approach 1:
The via structure is segmented into three distinct parts: a first via part with constant width, a second via part with gradually decreasing width, and a third via part with gradually increasing width. This segmentation allows each part to serve a specific function in preventing plating clogging and void formation while maintaining overall structural integrity
Solution Approach 2:
The via structure employs curved side surfaces in the second and third via parts, transitioning from straight to curved geometries. This curvature facilitates uniform plating deposition by preventing stress concentration and ensuring smooth material flow during the plating process
2Productivity
If the via width is reduced for miniaturization, then circuit integration increases, but physical rigidity decreases causing stress-related open defects
Solution Approach 1:
Different regions of the via structure have different width characteristics: the first via part maintains constant width for structural support, while the second and third via parts have varying widths optimized for plating quality. This local differentiation allows miniaturization in critical areas while maintaining rigidity where needed
Solution Approach 2:
The via structure combines multiple geometric configurations (constant width, decreasing width, increasing width) within a single via, creating a composite structural design that optimizes both mechanical strength and plating performance for miniaturized circuits
3Reliability
If the via plating process is performed on thick insulating layers (0.15T or more), then signal transmission is improved, but void formation occurs reducing plating quality
Solution Approach 1:
The via structure is pre-designed with specific width variations before plating to prevent plating defects. The second via part's decreasing width and third via part's increasing width are predetermined geometric features that guide plating material deposition, ensuring uniform coverage in thick insulating layers before plating occurs
Solution Approach 2:
The via width parameter is changed along the thickness direction of the insulating layer, creating a non-uniform width profile. This parameter variation optimizes plating material distribution in thick insulating layers, preventing void formation while maintaining signal transmission capability
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 design minimizes plating clogging and void formation, enhancing reliability and user satisfaction by ensuring consistent plating across the via structure, even in harsh environmental conditions.
Implementation Method 1
a manufacturing method involving laser processing to form the via hole with different glass fiber content regions
Data Source
AI summary
A circuit board according to an embodiment includes an insulating layer including an upper surface and a lower surface, and having a via hole passing through the upper surface and the lower surface in a thickness direction from the upper surface to the lower surface, wherein the via hole includes: a first via part adjacent to the upper surface and having a constant inclination angle along the thickness direction; a second via part adjacent to the lower surface and having a constant inclination angle along the vertical direction; and a third via part disposed between the first via part and the second via part and having an inclination angle different from an inclination angle of the first via part and an inclination angle of the second via part.