High Frequency Printed Wiring Board Narrow Width Design
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Solution Overview
Problem
The increasing number of antennas in information processing terminals, such as smartphones, requires multiple thin coaxial cables, occupying space and necessitating a more compact transmission solution while maintaining connection reliability.
Innovation Solution
A printed wiring board design with narrower signal and ground lines, utilizing non-overlapping ground connection vias and a flexible insulating base material, such as liquid crystal polymer, to reduce width without compromising connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple thin coaxial cables are used to connect antennas and substrate, then connection reliability is maintained, but space occupancy increases
Solution Approach 1:
Multiple signal lines and ground lines are integrated onto a single printed wiring board substrate, replacing multiple separate coaxial cables. The board combines multiple transmission channels (signal lines 21-24) and grounding paths (ground lines 31-35) into one unified structure, achieving space savings while maintaining connection reliability through controlled impedance design and proper grounding.
Solution Approach 2:
The invention transitions from a three-dimensional cable assembly to a two-dimensional planar wiring board structure. By laying out signal and ground lines in parallel on the substrate surface, the design eliminates the vertical stacking of multiple cables, reducing the overall height and footprint of the antenna connection system.
2Quantity of substance
If ground connection vias are arranged in a staggered manner, then wiring density is increased, but manufacturing precision requirements increase
Solution Approach 1:
The ground connection vias are divided into two separate groups: first ground connection vias (51, 53, 55) connected to the first ground line (31), and second ground connection vias (52, 54) connected to the second ground line (32). This segmentation allows each via group to be independently positioned and manufactured, reducing the overall precision requirements compared to a fully staggered arrangement while still achieving high wiring density.
Solution Approach 2:
Different via arrangement patterns are applied to different regions of the design. The first ground connection vias are positioned at specific locations optimized for the first ground line, while second ground connection vias are positioned for the second ground line. This localized optimization allows each via group to be manufactured with appropriate precision for its specific function, rather than requiring uniform high precision across all vias.
3Area of stationary object
If ground line width is reduced to narrow the board width, then space occupancy decreases, but connection reliability may deteriorate
Solution Approach 1:
The grounding system is segmented into multiple independent ground lines (31-35) with dedicated ground connection vias (51-55) for each. This segmentation allows the total ground connection functionality to be distributed across multiple narrower lines rather than requiring a single wide ground line, maintaining reliability through redundancy while achieving narrower overall board width.
Solution Approach 2:
Multiple narrow ground lines (31-35) are combined to provide the equivalent grounding capability of a single wide ground line. The parallel arrangement of multiple ground lines with distributed via connections achieves the same current distribution and thermal management as a wide ground line, while allowing the board width to be reduced.
Data Source
AI summary
A printed wiring board 1 for high frequency transmission according to an embodiment of the present invention includes: an insulating base material 10; a signal line 21 extending in a longitudinal direction of the insulating base material 10; ground wirings 31, 32 extending in the longitudinal direction while being spaced apart from the signal line 21 by a predetermined distance; a ground layer 40 formed on a major surface 10b; a plurality of ground connection vias 51 electrically connecting the ground wiring 31 and the ground layer 40; and a plurality of ground connection vias 52 electrically connecting the ground wiring 32 and the ground layer 40. A width of the ground wirings 31, 32 is smaller than a land diameter of the ground connection vias 51, 52. Then, the ground connection vias 51 and the ground connection vias 52 are arranged not to overlap each other in a width direction perpendicular to the longitudinal direction throughout a cable portion 90.