PCB Lead-in Line Design for Static Discharge and Solder Stability
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Solution Overview
Problem
The generation of potential differences between solder balls and fiducial marks on printed circuit boards due to static electricity leads to solder ball-shift phenomena, which existing technologies fail to effectively prevent.
Innovation Solution
A printed circuit board design incorporating plated lead-in lines with cut surfaces, where the second lead-in line connects the solder ball to the fiducial mark, preventing potential differences and thus mitigating the solder ball-shift phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solder ball is mounted on the printed circuit board, then electrical connection is established, but static electricity generates a potential difference between the solder ball and fiducial mark causing solder ball-shift phenomenon
Solution Approach 1:
The patent applies equipotentiality by electrically connecting the fiducial mark to the solder ball mounting position through a lead-in line. This creates an equipotential region that eliminates the potential difference between the fiducial mark and solder ball, thereby preventing the solder ball-shift phenomenon caused by electrostatic discharge. The lead-in line acts as an electrical pathway that equalizes the potential across critical regions.
Solution Approach 2:
The patent introduces a lead-in line as an intermediary element between the fiducial mark and the solder ball mounting position. This intermediary conductive structure provides a controlled electrical connection that dissipates static electricity safely, preventing direct discharge between the fiducial mark and solder ball that would cause shifting. The lead-in line mediates the electrostatic interaction by providing a designated discharge path.
2Reliability
If a lead-in line is used to connect solder ball to fiducial mark, then potential difference is suppressed, but the lead-in line structure becomes more complex
Solution Approach 1:
The patent merges the lead-in line with the existing fiducial mark structure, making the lead-in line an integrated part of the fiducial mark assembly rather than a separate component. This merging approach reduces overall structural complexity while maintaining the electrostatic discharge function. The lead-in line is configured to extend from the fiducial mark to the solder ball position, combining multiple functions into a unified structure.
Solution Approach 2:
The lead-in line serves multiple functions: it acts as a fiducial reference structure for alignment, provides an electrical discharge path for static electricity, and establishes an equipotential region. By making the lead-in line multi-functional, the patent reduces the need for additional separate components, thereby simplifying the overall device complexity while achieving reliable potential difference suppression.
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
The solution effectively suppresses potential differences between solder balls and fiducial marks, preventing solder ball-shift and ensuring stable connections on printed circuit boards.
Implementation Method 1
a plated lead-in line connecting a solder ball disposed on an outermost portion of a unit substrate and a fiducial mark
Implementation Method 2
a plated lead-in line having a cut surface formed through etchback etching
Data Source
AI summary
A printed circuit board includes: a base substrate including a unit region; a plurality of connection pads disposed on one surface of the base substrate; and first and second lead-in lines disposed on the one surface and respectively connected to at least a portion of the plurality of connection pads. The first and second lead-in lines have first and second cut surfaces on the one surface, respectively. The first cut surface is disposed in a position spaced apart from a side surface of the printed circuit board. The second cut surface is exposed to the side surface of the printed circuit board.