Polygon PWB Lands with Circular Concaves for Solder Bridge Prevention
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Solution Overview
Problem
Conventional methods for preventing solder bridges between neighboring lands on printed wiring boards (PWBs) either increase the mounting area, restrict component arrangement, or reduce the number of wiring patterns, making them inefficient for high-density component mounting and pattern density.
Innovation Solution
The use of metal plated polygon lands with an even number of sides, where each pair of facing sides are parallel and all corners have circular concaves, which directs solder towards the center of through holes, preventing bridges without increasing the mounting area and enhancing wiring pattern density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (protrusions, tapers, cutouts) are used to prevent solder bridges, then solder bridge prevention is improved, but the gap between lands becomes narrow reducing wiring patterns
Solution Approach 1:
The patent applies curvature by forming circular concaves at the corners of rectangular lands. This curved geometry modifies solder flow patterns compared to conventional protrusions or tapers, directing solder toward the center of through-holes while maintaining adequate gaps between adjacent lands for wiring patterns.
Solution Approach 2:
The invention applies local quality by adding circular concaves only at specific locations (corners) of the lands rather than modifying the entire land structure. This localized modification prevents solder bridges at critical corners while preserving the overall land geometry and gaps needed for wiring.
2Reliability
If longitudinal lands are used to prevent solder bridges, then solder bridge prevention is improved, but mounting area increases reducing component density
Solution Approach 1:
The patent uses circular concaves at land corners to prevent solder bridges, eliminating the need for longitudinal lands. This maintains compact land geometry and optimizes mounting area for high component density while still preventing solder bridges through the curved corner features.
3Reliability
If lands are arranged with fixed orientation to prevent solder bridges, then solder bridge prevention is improved, but component arrangement flexibility is reduced
Solution Approach 1:
The circular concave features at land corners provide isotropic solder flow control that works regardless of land orientation. This allows lands to be arranged in various orientations and patterns to accommodate different component layouts while maintaining solder bridge prevention effectiveness.
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 solution effectively prevents solder bridges between neighboring lands while maintaining high component mounting density and optimizing the number of wiring patterns between lands, as the circular concaves create a pressure difference that draws solder towards the center of the through holes.
Implementation Method 1
the circular concaves create a pressure difference that draws solder towards the center of the through holes
Data Source
AI summary
A PWB having a plurality of through holes into which electronic parts' leads are inserted, and metal plated lands formed around the through holes. The metal plated lands are polygon in which the number of sides is an even number and each pair of facing sides are parallel, and the lands have circular concaves at all the corners and the sides of polygon are arranged to be parallel to the sides of the neighboring metal plated lands.