Choke Coil Bonding Structure with Localized Surface Roughness
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Solution Overview
Problem
Conventional winding-type common mode choke coils face challenges in achieving high impact resistance and maintaining electrical characteristics due to inadequate bonding strength between the drum core and sheet core, which is influenced by the shape and properties of the bonding surfaces.
Innovation Solution
The proposed solution involves a common mode choke coil design with multiple contact areas and adhesive areas on the bonding surfaces of the drum core and sheet core, where the flange parts make direct contact with the sheet core without intervening materials, and an adhesive is applied between these areas to enhance bonding strength and inductance characteristics, along with a manufacturing method that includes forming the cores, winding conductive wires, and applying pressure to cure the adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bonding surfaces of the drum core and sheet core have high surface roughness to increase bonding strength, then the bonding strength improves, but it becomes difficult to achieve a constant thickness of the adhesive layer, causing unreliable mechanical strength and electrical characteristics
Solution Approach 1:
The bonding surfaces are designed with different local properties: the drum core bonding surface has a rougher texture to increase adhesive anchoring, while the sheet core bonding surface is kept smoother to ensure uniform adhesive distribution. This local differentiation allows the system to achieve both high bonding strength and consistent adhesive layer thickness.
2Manufacturing precision
If the bonding surfaces have low surface roughness to achieve uniform adhesive thickness, then the adhesive layer thickness becomes constant, but the amount of adhesive becomes small which may cause bonding strength to drop and impact resistance to decrease
Solution Approach 1:
By applying local quality differentiation to the bonding surfaces, the invention enables the drum core surface to provide mechanical interlocking through roughness while the sheet core surface maintains smoothness for uniform adhesive application. This resolves the contradiction between achieving sufficient adhesive quantity for strong bonding and maintaining consistent adhesive layer thickness.
3Strength
If extra adhesive is applied to increase bonding strength, then the bonding strength improves, but adhesive oozes out of the bonding surfaces creating unbonded areas with insufficient adhesive, causing bonding strength to drop
Solution Approach 1:
The differentiated surface roughness configuration allows the adhesive to be properly contained and distributed. The smoother sheet core surface prevents excessive adhesive from oozing out, while the rougher drum core surface ensures sufficient adhesive retention for strong bonding, achieving both high bonding strength and reliable bonding without unbonded areas.
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 achieves both high bonding strength and excellent inductance characteristics, improving the impact resistance and electrical stability of the common mode choke coil, while minimizing magnetic gaps and stray capacitance.
Implementation Method 1
an adhesive, between the contact areas, is disposed
Data Source
AI summary
A bonding structure of a sheet core and a pair of flange parts wherein the pair of flange parts is formed on both ends of a shaft part to constitute a drum core together with the shaft part; the sheet core is bonded, in a manner connecting the pair of flange parts across the shaft part, to the top faces of the flange parts facing away from the bottom faces of the flange parts to be mounted on a circuit board; and a coil-shaped conductor is constituted by sheathed conductive wires wound around the shaft part; wherein the bonding surfaces of each of the flange parts and the sheet core have multiple contact areas where the flange part makes direct contact with the sheet core, as well as adhesive areas between the contact areas where an adhesive is disposed.