Segmented Double-Sided PCB Via Structure for Void-Free Plating
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Solution Overview
Problem
Existing methods for filling penetrating holes in double-sided circuit boards with metal plating often result in voids and inadequate electrical connectivity due to the shape and size inconsistencies of the holes, which affect the board's electrical characteristics.
Innovation Solution
A method involving the formation of a penetrating hole comprising a first hole on one surface, a second hole on the opposite surface, and a third connecting hole with a smaller diameter, ensuring electrical connectivity between conductive circuits on both surfaces by filling the hole with conductive material, such as copper plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a penetrating hole is formed with consistent diameter throughout, then the plating process is simpler, but voids occur and electrical connectivity is inadequate
Solution Approach 1:
The penetrating hole is divided into three distinct segments: a first hole portion extending from the first surface, a second hole portion extending from the second surface, and a third hole portion connecting them. Each segment can have different diameters, allowing optimization for both plating fillability and electrical connectivity while avoiding voids.
Solution Approach 2:
Different portions of the penetrating hole are given different local properties through varying diameters. The first and second hole portions have larger diameters to facilitate plating material deposition, while the third connecting portion has a smaller diameter to maintain structural integrity and reduce void formation, creating locally optimized conditions for each function.
2Reliability
If the penetrating hole diameter varies significantly, then voids are reduced, but manufacturing precision becomes more difficult to control
Solution Approach 1:
By segmenting the hole into three controlled portions, each with specified diameter relationships (first diameter ≥ third diameter, second diameter ≥ third diameter), the manufacturing process can precisely control each segment separately, ensuring the third portion is sufficiently small to prevent voids while the first and second portions remain large enough for reliable plating.
3Ease of manufacture
If a simple single-hole structure is used, then manufacturing is easier, but electrical connection reliability deteriorates
Solution Approach 1:
The hole structure is segmented into three formable portions that can be created using standard drilling and plating processes, maintaining ease of manufacture. The segmented structure ensures reliable electrical connection by optimizing each portion's diameter for its specific function, preventing voids that would compromise connectivity.
Solution Approach 2:
The diameter parameter is changed at different locations along the penetrating hole's length. The first and second portions have larger diameters for easy formation and plating, while the third portion has a reduced diameter to ensure complete fillability and eliminate voids, thereby guaranteeing reliable electrical connection without complicating the manufacturing process.
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 enhances the reliability and efficiency of through-hole conductors by reducing voids and improving the electrical connection between conductive circuits, leading to better impedance and filling capabilities of the plating process.
Implementation Method 1
filling the penetrating hole with conductive material such as copper plating
Data Source
AI summary
A double-sided circuit board including a substrate having a first surface and a second surface on an opposite side of the first surface and having a penetrating hole extending between the first surface and the second surface, a first conductive circuit formed on the first surface of the substrate, a second conductive circuit formed on the second surface of the substrate, and a through-hole conductor formed in the penetrating hole of the substrate and electrically connecting the first conductive circuit and the second conductive circuit. The penetrating hole comprises a first hole having a first opening with a diameter R1 on the first surface of the substrate, a second hole having a second opening with a diameter R2 on the second surface of the substrate, and a third hole connecting the first hole and the second hole and having a diameter smaller than at least one of R1 and R2.