Coil Device Electrode Segmentation for Bonding Reliability
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Solution Overview
Problem
Conventional coil devices face reliability issues due to deteriorated bonding conditions between electrodes and winding coils when exposed to heat during reflow, and exposed connecting wires are prone to external impacts and production variations.
Innovation Solution
A coil device design featuring a winding coil with an extension line, conductive electrodes with a connecting wire part protected by a magnetic material, and a protective face that reduces contact area and stress, enhancing durability and reliability by covering the connecting wire part and preventing pull-apart forces caused by linear expansion coefficient differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the connecting part between electrode and winding coil is covered with magnetic material, then the connecting wire part is protected from external impacts, but the bonding condition between electrode and winding coil deteriorates due to heat during reflow
Solution Approach 1:
The electrode is divided into distinct functional regions: a connecting wire part with reduced thickness for flexibility and bonding, and a base part with sufficient thickness for structural support and mounting. This segmentation allows the connecting wire part to maintain good bonding conditions while being covered by magnetic material for protection.
Solution Approach 2:
The electrode exhibits local quality variations through thickness changes: the connecting wire part has reduced thickness to improve bonding characteristics and flexibility, while the base part maintains sufficient thickness for mechanical strength. This local differentiation resolves the contradiction between protection and bonding reliability.
2Reliability
If the connecting wire part is exposed from magnetic material, then the bonding condition is maintained, but the connecting wire part receives external impacts and shows large production variation
Solution Approach 1:
The electrode is segmented into a connecting wire part and base part, with the connecting wire part having reduced thickness. This segmentation allows the magnetic material to cover and protect the connecting wire part while the base part remains exposed for mounting, thus protecting against external impacts while maintaining bonding reliability.
Solution Approach 2:
The magnetic material serves as a protective covering that cushions the connecting wire part from external impacts before such impacts can occur. This beforehand protection allows the connecting wire part to be covered while maintaining its bonding functionality.
3Duration of action of stationary object
If the connecting wire part is covered with magnetic material, then durability is improved, but residual stress from molding affects the connecting condition
Solution Approach 1:
The electrode is segmented with the connecting wire part having reduced thickness, making it more flexible and better able to accommodate residual stresses from magnetic material molding. This segmentation allows the connecting wire part to be covered by magnetic material for durability while the flexible design absorbs molding stresses.
Solution Approach 2:
The thickness parameter of the electrode is changed in the connecting wire part to create a flexible region that can accommodate residual stresses from magnetic material molding. This parameter change allows the connecting wire part to maintain reliability under stress while being covered for durability.
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 design improves the reliability of the connecting condition between the winding coil and electrode, enhances durability, and simplifies production by protecting the connecting wire part from external impacts and residual stress, while maintaining good bonding properties for surface mounting.
Implementation Method 1
a magnetic part including a magnetic material and covering at least said winding part and said connecting wire part
Implementation Method 2
the extension line part is placed between the protective face and the connecting wire face
Implementation Method 3
the area in contact with the magnetic part with respect to the connecting part of the extension line part is reduced compared to the case without the protective face. Therefore, such coil device can prevent from receiving the force trying to pull apart the connecting part of the extension line part from the electrode, which is caused by the difference between the linear expansion coefficient
Implementation Method 4
the protective face has an effect to protect the connecting part between the extension line part and the electrode from the residual stress generated during the molding of the magnetic part
Data Source
AI summary
A coil device comprising; a winding coil including Cu and having a winding part and an extension line part which is pulled out from said winding part, a pair of electrodes made of a conductive material having, a connecting wire part having a connecting wire face connected with the extension line part and a protective face sandwiching said extension line part with said connecting wire face, and a base part provided with a mounting base face at one of the faces of the base and connected to said connecting wire part, a magnetic part including a magnetic material and covering at least said winding part and said connecting wire part.