Wiring Board Coil Layout for Stable Magnetic Flux Under Solder Variation
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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
The wiring board design includes a coil conductor with a winding axis intersecting the surface, and a configuration of conductive members where a first conductive member overlaps the opening of the coil conductor, and a second conductive member is positioned deviated from the opening, with the area of the first conductive member being smaller than the second.
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 extracts the harmful conductive member (solder ball) from its position where it directly overlaps the coil conductor opening. By relocating the conductive member to a position deviated from the opening, the harmful influence on magnetic flux is removed while maintaining the electrical connection function through the land electrode.
Solution Approach 2:
The patent applies local quality by creating different area ratios for conductive members at different positions. The first conductive member (overlapping the opening) has a smaller area ratio, while the second conductive member (deviated from opening) has a larger area ratio. This local differentiation optimizes the balance between electrical connection and magnetic flux stability.
2Ease of manufacture
If conductive members are positioned to overlap the coil conductor opening, then electrical connection is facilitated, but magnetic flux is adversely affected
Solution Approach 1:
The land electrode serves as an intermediary between the conductive member and the coil conductor. It provides the electrical connection function while the conductive member is positioned deviated from the opening, thus the harmful magnetic flux interference is avoided. The land electrode mediates between the need for electrical connection and the need to protect magnetic flux.
Solution Approach 2:
The patent changes the spatial arrangement from direct vertical overlap (one-dimensional alignment) to a deviated position with area ratio control (two-dimensional arrangement). By controlling the area ratio of the conductive member relative to the land electrode, the solution moves from simple overlap to a more complex spatial configuration that reduces magnetic flux interference while maintaining electrical connection.
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 configuration reduces the influence of variations in the size of the conductive members on the magnetic flux, thereby stabilizing the performance of the coil conductor and the wiring board.
Implementation Method 1
affects a magnetic flux formed when a current flows through the thin film inductive element
Data Source
AI summary
A wiring board includes at least one insulating layer, plurality of conductive members, at least one land electrode formed at position overlapping first surface in plan view of insulating layer as viewed from first surface side, land electrode being connected to each of at least one conductive member, and coil conductor provided inside insulating layer or on second surface on back side of first surface in insulating layer and having winding axis intersecting first surface. Plurality of conductive members includes first conductive member at position where at least part of the first conductive member overlaps opening of the coil conductor in plan view seen from first surface side, and second conductive member at position deviated from opening of coil conductor in plan view seen from first surface side. Area of first conductive member is smaller than area of second conductive member in plan view seen from first surface side.