PCB RF Transition via Rotation Reduces Signal Loss
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Solution Overview
Problem
Current RF transition methods on Printed Circuit Boards (PCBs) face inefficiencies, such as high signal loss and increased production costs due to the use of via-in-pad and stacked-via transitions, which can compromise solder joint strength and assembly yield, and require resin-filling and capping processes.
Innovation Solution
The implementation of a triple microvia structure connected to a triple buried-via structure, rotated with respect to each other, which allows for efficient RF signal transmission between a Ball Grid Array (BGA) and an antenna on a multilayer PCB, eliminating the need for resin-filling and capping processes and reducing RF losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via-in-pad and stacked-via transitions are used for RF signal transmission, then signal transmission capability is improved, but solder joint strength and assembly yield deteriorate
Solution Approach 1:
The RF transition structure is segmented into multiple functional zones: a first section with via-in-pad configuration for optimal signal transmission, and a second section with stacked-via configuration for structural support. This segmentation allows each zone to perform its specialized function without compromising the other, resolving the contradiction between signal transmission capability and solder joint strength.
2Manufacturing precision
If resin-filling and capping processes are applied to via transitions, then manufacturing precision is improved, but production cost and process complexity increase
Solution Approach 1:
The invention extracts and eliminates the resin-filling and capping processes from the manufacturing workflow by designing a mechanical stop structure that inherently defines via depth and position. This structural approach replaces the need for chemical filling processes, maintaining manufacturing precision while significantly reducing process complexity and production cost.
3Reliability
If traditional via transitions are used, then signal transmission is achieved, but RF signal loss increases
Solution Approach 1:
The via transition structure implements local quality optimization by configuring different via arrangements in different sections: the first section uses via-in-pad with specific positioning to minimize RF loss in the critical signal path, while the second section uses stacked-vias for structural integrity. This localized optimization ensures minimal RF signal loss throughout the transition while maintaining overall structural requirements.
Data Source
AI summary
For example, an apparatus may include a Printed Circuit Board (PCB) including a Ball Grid Array (BGA) on a first side of the PCB, the BGA configured to connect a Surface Mounted Device (SMD) to the PCB; an antenna disposed on a second side of the PCB opposite to the first side, the antenna to communicate a Radio Frequency (RF) signal of the SMD; and an RF transition to transit the RF signal between the BGA and the antenna, the RF transition including a plurality of signal buried-vias; a first plurality of microvias configured to transit the RF signal between the plurality of signal buried-vias and a ball of the BGA, the first plurality of microvias are rotationally misaligned with respect to the plurality of signal buried-vias; and a second plurality of microvias configured to transit the RF signal between the plurality of signal buried-vias and the antenna.