Coil Component Joining Member for Reflow Mounting Stability
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Solution Overview
Problem
Conventional electronic components with metal terminals experience positional displacement during reflow mounting due to solder melting, leading to unreliable connections and size inconsistencies.
Innovation Solution
A coil component design featuring a core with flange portions, wire winding, electrode connections, and a joining member with a higher melting point than the mounting solder to prevent positional displacement, along with thermal shock resistance enhancements through cutouts and specific terminal configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the melting point of the solder used for connecting the metal terminal and the terminal electrode is lower than or the same as the melting point of the solder used for connecting the metal terminal and the mounting substrate, then the reflow mounting process can be simplified, but the solder connecting the metal terminal and the terminal electrode may melt at the time of reflow mounting, leading to significant displacement or rotation of the metal terminal
Solution Approach 1:
The patent introduces a joining member with a specific melting point parameter that is higher than the mounting solder but lower than or equal to the terminal electrode solder. This parameter differentiation allows the joining member to remain intact during reflow mounting while the mounting solder melts, preventing metal terminal displacement. The key is changing the melting point parameter of the joining member to create a thermal hierarchy in the connection structure.
Solution Approach 2:
The joining member acts as an intermediary component between the metal terminal and the terminal electrode. It mediates the thermal stress and mechanical connection during reflow mounting, absorbing the thermal shock and preventing direct transmission of heat to the terminal electrode-solder connection. This intermediary structure solves the contradiction by protecting the critical connection while allowing the mounting process to proceed.
2Reliability
If the joining member has a melting point higher than the mounting solder to prevent displacement during reflow, then connection reliability is improved, but the joining member may mix with the mounting solder, lowering the melting point of the joining member
Solution Approach 1:
The patent segments the connection structure into distinct functional zones: the joining member connection area and the mounting solder area. By providing a supporting structure (such as a protrusion or recess) that physically separates these zones, the design prevents mixing between the joining member material and mounting solder while maintaining their respective functions. This segmentation ensures the joining member's melting point remains unchanged despite the presence of lower-melting-point mounting solder nearby.
3Volume of moving object
If the metal terminal is positioned immediately under a winding portion of the wire, then the component size is reduced, but resin accumulation occurs between the winding portion and metal terminal, causing stress on the wire during thermal shock
Solution Approach 1:
The patent extracts or removes the metal terminal from the position immediately under the winding portion, creating a deliberate gap or spacing between these components. This extraction prevents resin accumulation in the critical area where wire and terminal meet, eliminating the source of thermal shock stress. Although this slightly increases component size, it prioritizes wire connection reliability by removing the harmful resin trapping configuration.
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 coil component effectively maintains the connection state between the electrode and metal terminal at the melting point of the mounting solder, preventing displacement and enhancing thermal shock resistance, thus ensuring reliable connections and preventing resin-induced stress on the wire.
Implementation Method 1
the joining member has a heat resistance property retaining a connection state between the electrode portion and the metal terminal at least at the melting point of the mounting solder
Implementation Method 2
the melting point of the solder used for connecting the metal terminal and the terminal electrode is lower than or the same as the melting point of the solder used for connecting the metal terminal and the mounting substrate, the solder connecting the metal terminal and the terminal electrode may melt at the time of the reflow mounting
Data Source
AI summary
A coil component has a core having a winding core portion and a flange portion disposed on each of both ends of the winding core portion, the flange portion including a foot portion; a wire wound around the winding core portion; an electrode portion disposed on a bottom surface of the foot portion of the flange portion and connected to the wire; a metal terminal to be connected via a mounting solder to a mounting substrate; and a joining member connecting the metal terminal to the electrode portion. The joining member has a heat resistance property retaining a connection state between the electrode portion and the metal terminal at least at the melting point of the mounting solder.