Wiring Board Land Electrode Layout for Stable Coil Magnetic Flux
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Solution Overview
Problem
Variations in the diameter of solder balls on a wiring board affect the magnetic flux formed by a thin film inductive element, leading to inconsistent performance across manufactured boards.
Innovation Solution
A wiring board design with land electrodes positioned to overlap or deviate from the coil conductor's opening, where the overlapping electrodes have a larger area than the deviating electrodes, minimizing the influence of conductive member size variations on magnetic flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are provided on the thin film inductive element, then electrical connection is achieved, but variations in solder ball diameter cause variations in magnetic flux and performance inconsistency
Solution Approach 1:
The patent introduces a land electrode as an intermediary component between the solder ball and the coil conductor. The land electrode is positioned to overlap the opening of the coil conductor in plan view, acting as a mediator that shields the coil conductor from the magnetic flux variations caused by solder ball diameter variations, thereby improving performance consistency
Solution Approach 2:
The patent segments the electrical connection structure into distinct components: the land electrode and the coil conductor are separated in the thickness direction of the insulating layer. This segmentation allows the land electrode to independently control the magnetic flux interaction, preventing solder ball variations from directly affecting the coil conductor
2Reliability
If the conductive member is positioned to overlap the coil conductor opening, then magnetic flux influence is reduced, but electrode area must be increased
Solution Approach 1:
The patent applies local quality by making the land electrode area non-uniform: the first land electrode that overlaps the coil conductor opening has a larger area to effectively shield magnetic flux, while other land electrodes have smaller areas. This localized area variation optimizes magnetic flux stability without unnecessarily increasing the total electrode area
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
Reduces the impact of conductive member size variations on magnetic flux, stabilizing performance across boards and enhancing consistency.
Implementation Method 1
the solder ball affects a magnetic flux formed when a current flows through the thin film inductive element
Data Source
AI summary
To provide wiring board capable of reducing influence of variation in size of conductive member on coil conductor. Wiring board according to present disclosure includes insulating layer, plurality of land electrodes formed on lower surface of insulating layer, solder ball formed on surface of at least one of plurality of land electrodes, and coil conductor provided inside insulating layer and having winding axis intersecting lower surface. Plurality of land electrodes includes electrode at a position overlapped opening of coil conductor in plan view seen at the wiring board from lower surface side, and second electrode at a position deviated from opening of coil conductor in plan view. Area of first electrode is larger than area of second electrode in plan view.