Tapered Via Conductor Structure for Coil Connection Reliability
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Solution Overview
Problem
Conventional coil components face reliability issues due to stress concentration at the connection between via conductors and inductors caused by thermal expansion and contraction during mounting, leading to potential breakage and peeling.
Innovation Solution
The integration of via conductors with a truncated cone shape, where the diameter of the end portion near the inductor circuit pattern is larger than that near the external terminal, reduces stress concentration and enhances connection reliability by forming the via conductors and external terminals from the same conductive material, ensuring they are continuously formed during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional via conductor with uniform diameter is used, then the manufacturing process is simple, but stress concentration occurs at the connection between via conductor and inductor during thermal expansion and contraction, leading to breakage and poor connection reliability
Solution Approach 1:
The via conductor is designed with an asymmetric diameter profile where the diameter varies along its length. Specifically, the diameter at the inductor connection end is larger than the diameter at the external terminal end, creating an asymmetric structure that reduces stress concentration at the critical connection point during thermal expansion and contraction cycles.
Solution Approach 2:
The via conductor exhibits local quality variation along its length, with different diameters at different positions. The larger diameter at the inductor connection end provides enhanced mechanical strength and stress distribution exactly where the connection reliability is most critical, while the smaller diameter at the external terminal end maintains overall structural efficiency.
2Reliability
If the via conductor diameter is increased to reduce stress concentration, then connection reliability improves, but the resin layer thickness and overall component size must be increased
Solution Approach 1:
The asymmetric diameter profile allows the via conductor to concentrate its cross-sectional area where needed (at the inductor connection end) rather than uniformly throughout. This means the resin layer thickness can remain thin overall while still providing adequate stress resistance at the critical connection point through the localized diameter increase.
Solution Approach 2:
By concentrating the increased diameter (and thus the stress-bearing capacity) only at the inductor connection end where it is most needed, the design avoids the need to increase the resin layer thickness throughout the entire via conductor length. The local quality enhancement is precisely targeted at the critical stress point.
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 effectively relaxes stress at the connection points, minimizing breakage and peeling, thereby improving the reliability of the connection between via conductors and inductor circuit patterns.
Implementation Method 1
when heat is applied from the outside due to component mounting by a reflow method or the like, stress due to thermal expansion and contraction of a resin layer may be concentrated on a connection portion between a via conductor and an inductor
Data Source
AI summary
An electronic component capable of improving connection reliability between a via conductor and a circuit pattern. An electronic component includes a circuit pattern; an insulating resin layer covering the circuit pattern; a via conductor provided inside the insulating resin layer and connected to the circuit pattern; and a wiring member connected to the circuit pattern via the via conductor. The via conductor and the wiring member are integrally formed, and in the via conductor, a diameter of an end portion on a side close to the circuit pattern is larger than a diameter of an end portion on a side close to the wiring member.