Multilayer Circuit Board Via Structure for Lower Interlayer Resistance
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Solution Overview
Problem
The resistance value of interlayer connection conductors in multilayer circuit boards increases due to the lower conductivity of second via portions formed by conductive paste, leading to deteriorated substrate characteristics.
Innovation Solution
The circuit board design includes interlayer connection conductors with varying conductivity portions, where the height and conductivity ratios are optimized to minimize resistance, using plated vias and paste vias in specific configurations to maintain effective connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If second via portions are formed by filling with conductive paste, then manufacturing complexity is reduced and ease of manufacture is improved, but the resistance value of interlayer connection conductors increases and reliability deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the via portions into two types: first via portions with high conductivity (formed by plating) and second via portions with lower conductivity (formed by conductive paste). This local differentiation allows the high-conductivity plating to be strategically placed at critical connection points while using the simpler paste-filling method for less critical portions, thus maintaining overall reliability while improving ease of manufacture.
Solution Approach 2:
The interlayer connection conductor is segmented into multiple via portions (first via portions and second via portions) with different formation methods and conductivity characteristics. This segmentation allows each portion to be optimized independently - the plating-based first via portions provide low resistance paths where needed, while the paste-based second via portions provide simpler manufacturing elsewhere, resolving the contradiction between ease of manufacture and reliability.
2Ease of manufacture
If the ratio of second via portions to interlayer connection conductor increases, then ease of manufacture is improved, but the resistance value of the entire interlayer connection conductor increases and substrate characteristics deteriorate
Solution Approach 1:
The patent implements local quality by assigning different formation methods to different via portions based on their functional requirements. First via portions (requiring high conductivity) are formed by plating, while second via portions (where manufacturing simplicity is prioritized) are formed by conductive paste filling. This localized approach allows the ratio of second via portions to be increased for ease of manufacture while maintaining manufacturing precision in critical areas through the use of first via portions.
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 effectively reduces or prevents an increase in the overall resistance of interlayer connection conductors, enhancing the performance and reliability of the circuit board.
Implementation Method 1
forming a first via portion partway through a hole by plating a hole provided in an insulating layer with conductor foil
Implementation Method 2
forming a second via portion by filling a remaining portion of the hole in which the first via portion is formed with a conductive paste
Data Source
AI summary
A circuit board includes an insulating layer, first and second interlayer connection conductors penetrating an insulating layer in a thickness direction, first and second conductor layers respectively on first and second main surfaces of the insulating layer and connected to the first interlayer connection conductor, and third and fourth conductor layers respectively on the first and second main surfaces and connected to the second interlayer connection conductor. The first and second interlayer connection conductors respectively include first and second portions and third and fourth portions. When a height of the first portion is A1, a height of the second portion is B1, a height of the third portion is A2, a height of the fourth portion is B2, a height of the first interlayer connection conductor is T1, and a height of the second interlayer connection conductor is T2, relationships of T1<T2 and B1/A1>B2/A2 are satisfied.