Drum-Core Coil Terminal Bonding for Thermal Shock Resistance
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Solution Overview
Problem
Existing coil components experience peeling of metal terminals from drum-shaped cores due to thermal shock caused by differences in expansion and contraction between ferrite cores and printed circuit boards during heat cycles.
Innovation Solution
The coil component features an adhesive layer with both thick-walled and thin-walled portions to disperse stress and increase adhesion strength, preventing peeling during heat cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a uniform thin adhesive layer is used to mount metal terminals on the flange portion, then the adhesive forms firmly adhered portions, but the adhered portions peel during thermal shock due to expansion contraction differences
Solution Approach 1:
The adhesive layer is designed with non-uniform thickness, creating thick-walled portions and thin-walled portions in different locations. The thick-walled portions are positioned at areas prone to peeling during thermal shock to provide enhanced stress resistance, while thin-walled portions maintain firm adhesion in stable areas. This local variation in adhesive thickness allows the structure to withstand thermal expansion and contraction differences between the ferrite core and printed circuit board.
2Reliability
If the adhesive layer thickness is increased uniformly, then stress dispersion improves, but adhesion strength decreases due to excessive thickness
Solution Approach 1:
Rather than uniformly increasing adhesive layer thickness, the invention applies thicker adhesive only at specific thick-walled portions where peeling stress concentrates during thermal shock. The thin-walled portions maintain optimal thickness for strong adhesion. This localized approach disperses stress where needed without compromising overall adhesion strength.
3Ease of manufacture
If the metal terminal structure is simplified, then manufacturing becomes easier, but the terminal cannot withstand thermal shock when soldered to the printed circuit board
Solution Approach 1:
The metal terminal is designed with a localized thickened portion at the mounting area where it contacts the adhesive layer on the flange portion. This local thickening provides enhanced mechanical strength and thermal shock resistance at the critical interface, while the rest of the terminal maintains its simple structure for ease of manufacturing and soldering to the printed circuit board.
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 adhesive layer effectively disperses stress and maintains high adhesion strength between metal terminals and drum-shaped cores, preventing peeling even under thermal shock.
Implementation Method 1
differences in expansion and contraction between ferrite cores and printed circuit boards during heat cycles
Implementation Method 2
an adhesive is used. The adhesive is applied to portions where the rising portions 76 of the metal terminals 67 and 69 and the outer end surface 73 of the flange portion 65 face each other
Data Source
AI summary
A coil component includes a drum-shaped core that includes a flange portion, a metal terminal that is mounted on the flange portion and that is formed from a metal plate, and an adhesive layer that contacts both a rising portion of the metal terminal and a rising surface of the flange portion. The adhesive layer includes a thick-walled portion and a thin-walled portion having different thicknesses.