Coil Device Terminal Electrode Segmentation for Bonding Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional coil devices used as pulse transformers face issues with residue coating films causing voids and reduced bonding strength due to heat effects during thermocompression, leading to compromised connection reliability and adhesiveness.
Innovation Solution
The coil device features a core member with a winding core and flange, where the terminal electrode has separate wire connecting and mounting parts, reducing residue coating film adherence and heat influence, enhancing bonding strength and reliability while allowing for a more compact design with lower DC internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wire is connected by thermocompression to the terminal electrode, then the wire connection is achieved, but residue of coating film remains on the mounting face causing voids and reduced connection reliability
Solution Approach 1:
The terminal electrode is divided into two distinct parts: a wire connecting part for thermocompression connection and a mounting face for substrate mounting. This segmentation ensures that the wire connecting operation occurs on one part while the mounting face remains separate, preventing coating film residue from the wire connection area from contaminating the mounting surface, thus eliminating voids and improving connection reliability
Solution Approach 2:
The harmful factor (coating film residue) is extracted from the mounting face by performing the wire thermocompression connection on a separate wire connecting part. The mounting face is kept free from wire connection operations, thereby extracting the source of contamination and ensuring a clean mounting surface for reliable substrate connection
2Strength
If the wire is connected by thermocompression, then the wire is secured to the terminal electrode, but the Sn layer melts and diminishes on the mounting face deteriorating adhesiveness
Solution Approach 1:
The terminal electrode is segmented into a wire connecting part that undergoes thermocompression heating and a mounting face that remains thermally isolated. This spatial separation ensures that the heat from wire connection does not reach the mounting face, preventing Sn layer melting and preserving adhesiveness for substrate mounting
Solution Approach 2:
The wire connecting part acts as an intermediary that absorbs and isolates the thermal energy from thermocompression. By confining the heating operation to this separate part, the mounting face is protected from thermal influence, maintaining the integrity of the Sn layer and its adhesiveness properties
3Reliability
If the wire connecting part is positioned away from the winding core, then the mounting part can be separate, but the wire length increases increasing DC internal resistance
Solution Approach 1:
The terminal electrode structure is designed with local differentiation: the wire connecting part is positioned close to the winding core to minimize wire length and DC resistance, while the mounting face is positioned separately to ensure bonding reliability. This local optimization allows each part to serve its function efficiently without compromising the other
4Ease of operation
If the wire connecting part protrudes towards the width direction of the flange, then the wire connection is accessible, but the coil device becomes larger and harder to handle
Solution Approach 1:
Instead of extending the wire connecting part in the width direction of the flange, the design utilizes the axial direction (length direction) of the flange to position the mounting face. This dimensional reorientation allows the wire connecting part to remain compact in the width direction while providing adequate accessibility, thereby reducing the overall device volume without compromising ease of operation
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 minimizes voids and cracks, improves connection reliability, and maintains adhesiveness by separating the wire connecting and mounting parts, resulting in enhanced bonding strength and reduced DC internal resistance, making the coil device more compact and easier to handle.
Implementation Method 1
when one end of the wire is connected by thermocompression to the wire connecting part of the terminal electrode
Data Source
AI summary
A coil device having high bonding strength and bonding reliability has a core member including a winding core and a flange, wires wound around the winding core and one end being positioned at the flange, and terminal electrodes provided to the flange. Each of the terminal electrodes has a wire connecting part where one ends of the wires are connected, and a mounting part continuously formed with the wire connecting part at the side close to the winding core with respect to the wire connecting part along the axis direction of the winding core. The wire connecting part is provided at a position lower than the mounting part along the height direction of the flange.