Stepped Terminal Electrode Inductor for Mounting Reliability
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Solution Overview
Problem
The miniaturization of inductors for electronic devices leads to a decrease in terminal electrode area, resulting in reduced connection strength with the circuit board, compromising mounting reliability.
Innovation Solution
An inductor design featuring a core with a columnar shaft and supports, where the terminal electrodes have an increased surface area due to a central portion being higher than the end portions, and side surface electrodes with a gradually increasing height, minimizing magnetic flux obstruction and reducing eddy-current loss, while maintaining sufficient connection strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the inductor size is reduced to meet miniaturization requirements, then the inductor can be mounted in compact electronic devices, but the terminal electrode area decreases resulting in reduced connection strength with the circuit board
Solution Approach 1:
The terminal electrode transitions from a conventional planar structure to a three-dimensional stepped structure with multiple height levels. The central portion rises to a first height while end portions remain at a second height, creating vertical dimensionality that increases effective surface area without expanding the inductor's footprint, thereby maintaining strong connections in miniaturized devices
Solution Approach 2:
The terminal electrode employs a nested stepped configuration where lower-level end portions are surrounded by higher-level central portions. This nested arrangement maximizes the use of vertical space within the limited footprint, effectively increasing the connection surface area without increasing the overall inductor dimensions
2Strength
If the terminal electrode surface area is increased to improve connection strength, then mounting reliability improves, but the inductor size increases
Solution Approach 1:
Instead of expanding the terminal electrode horizontally which would increase inductor footprint, the design utilizes the vertical dimension by creating a stepped structure with multiple height levels. This allows the effective surface area to increase while the horizontal footprint remains constrained, solving the contradiction between connection strength and size
Solution Approach 2:
The terminal electrode design changes the height parameter spatially, creating regions of different heights (first height for central portion, second height for end portions). This parameter variation within the same component allows increased effective area without increasing overall dimensions, maintaining miniaturization while improving connection strength
3Strength
If the terminal electrode height is increased to improve connection strength, then connection strength increases, but magnetic flux obstruction increases and eddy-current loss increases
Solution Approach 1:
The terminal electrode implements local quality variation with different height regions serving different functions: the central portion at first height provides enhanced connection strength, while the end portions at second height minimize magnetic flux obstruction. This localized differentiation allows the structure to simultaneously achieve strong connections and reduced energy loss
Solution Approach 2:
The terminal electrode breaks symmetry by creating an asymmetric stepped profile where the central portion differs in height from the end portions. This asymmetric design optimizes both connection strength (through the elevated central region) and magnetic flux performance (through the lower end regions that cause less obstruction)
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 design enhances connection strength with the circuit board, improves inductance efficiency, and suppresses decreases in the Q-factor, ensuring reliable mounting and performance in compact electronic devices.
Implementation Method 1
A magnetic flux generated at the shaft of the core due to a current flowing through the wire
Implementation Method 2
a wire wound around the shaft and having an end portion connected to the terminal electrode
Data Source
AI summary
An inductor includes a core including a columnar shaft and a support on an end portion of the shaft, a terminal electrode disposed on the support, and a wire wound around the shaft and having an end portion connected to the terminal electrode. The terminal electrode includes a bottom surface electrode on a bottom surface of the support and an end surface electrode on an end surface of the support. The end surface electrode includes an end portion in a width direction of the end surface and a central portion in the width direction of the end surface. The central portion is positioned higher than the end portion.