Segmented Through-Hole Via for Stub Reduction
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Solution Overview
Problem
Conventional methods for reducing stubs in multilayer printed boards, such as back-drilling, require additional machining steps and restrict mounting layout flexibility, as they often result in larger holes that reduce the mountable area and increase design complexity.
Innovation Solution
A through-hole via configuration featuring a first and second conductor separated by a gap, with land portions connecting them to different insulating layers, allowing for reduced stub lengths without the need for back-drilling, thus maintaining design flexibility and minimizing design changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If back-drilling is performed to remove stubs, then stub length is reduced, but manufacturing complexity increases due to additional machining steps
Solution Approach 1:
The through-hole conductor is divided into multiple separate conductors (first through-hole conductor and second through-hole conductor) within the same hole. This segmentation allows the stub portion to be electrically isolated and removed by simply not plating that section, eliminating the need for back-drilling while still achieving stub reduction.
2Length of moving object
If back-drilling is performed to remove stubs, then stub length is reduced, but mountable area decreases due to larger hole diameter
Solution Approach 1:
By segmenting the conductor into multiple separate conductors within the same hole diameter, the stub can be removed electrically without physically enlarging the hole. The hole diameter remains the same as standard through-holes, preserving the mountable area while still achieving stub length reduction.
3Length of moving object
If back-drilling is performed to remove stubs, then stub length is reduced, but mounting layout freedom is restricted
Solution Approach 1:
The segmented conductor structure allows stub removal without back-drilling, meaning no additional machining steps are required. This maintains flexibility in mounting layout design as components can be positioned without needing to account for back-drilled areas, preserving mounting layout freedom.
4Ease of manufacture
If conventional through-hole configuration is used, then manufacturing is simple, but stub length is long causing signal degradation
Solution Approach 1:
The through-hole conductor is segmented into multiple separate conductors, with the stub portion being one of these segmented conductors. During the plating process, the stub conductor can be selectively removed by masking or simply not plating that section, achieving stub reduction without adding significant manufacturing complexity.
Solution Approach 2:
The stub portion is extracted or removed from the continuous conductor by creating a gap or separation. This can be done by masking the stub area during plating or by removing the plated stub portion after plating, effectively extracting the harmful stub element while keeping the main signal path intact.
Data Source
AI summary
A through-hole via penetrating, in a thickness direction, through a circuit board provided with multiple wiring layers in which a conductor pattern is formed on a surface of an insulating layer, wherein the through-hole via has a first through-hole conductor that is disposed inside a hole penetrating through the circuit board and that is formed from a conductor; a second through-hole conductor that is disposed inside the hole so as to be spaced, in a circumferential direction of the hole, from the first through-hole conductor; a first land portion that connects the first through-hole conductor to the conductor pattern on one insulating layer; and a second land portion that connects the first through-hole conductor with the second through-hole conductor on another insulating layer different from the one insulating layer.