PCB Positioning Pad Arc Recess for Solder Leakage Prevention
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Solution Overview
Problem
In surface mount technology, the close spacing between positioning holes and pads on circuit boards often results in solder leakage due to insufficient edge space, compromising accurate positioning and reliability of electronic components.
Innovation Solution
A circuit board design featuring arc-shaped recesses at the edges of positioning pads near positioning holes, with a center-to-center spacing of 0.2 mm to 0.5 mm, combined with a solder mask around the pads, to maintain accurate positioning while preventing solder leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the positioning hole and positioning pad are placed close to each other for accurate positioning, then positioning precision is improved, but solder leakage occurs due to insufficient edge space
Solution Approach 1:
The positioning pad is segmented by introducing an arc-shaped recess that divides the pad into distinct regions. This segmentation allows the pad to maintain small center-to-center spacing with the positioning hole for accurate positioning, while the recess creates sufficient edge space to prevent solder leakage by separating the solder application area from the hole edge.
Solution Approach 2:
The arc-shaped recess modifies the local geometry of the positioning pad only in the critical area near the positioning hole. This local modification provides sufficient edge clearance to prevent solder leakage while maintaining the overall small spacing between the positioning hole and pad centers for accurate positioning. The rest of the pad retains its full functionality for electrical connection.
2Measurement precision
If the center-to-center spacing between positioning hole and positioning pad is reduced for accurate positioning, then positioning accuracy is improved, but the space between edges becomes insufficient preventing solder leakage
Solution Approach 1:
An arc-shaped recess is introduced into the positioning pad geometry. This curved feature strategically removes material from the pad edge near the positioning hole, creating sufficient clearance to prevent solder leakage. The curvature of the recess allows for smooth solder flow while maintaining the required edge distance, enabling small center-to-center spacing without compromising the edge space needed for reliable soldering.
Data Source
AI summary
A circuit board includes four positioning pads placed on a surface of the circuit board, four positioning holes corresponding to the positioning pads, respectively, and a solder mask placed on the surface around the periphery of the positioning pads. An arc-shaped recess is defined at a side of each positioning pad near the corresponding positioning hole and the space between the edges of the positioning pad and the positioning hole ranges from 0.2 mm to 0.5 mm.