Pulse Transformer Terminal Electrode Bonding With Laser Stripe Marks
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Solution Overview
Problem
Conventional coil devices used as pulse transformers face issues with residue coating films on terminal electrodes, leading to voids and cracks during mounting, which compromises bonding strength and reliability.
Innovation Solution
A coil device with a core member, wire wound around a winding core, and a terminal electrode connected with a lead wire, featuring an easy bonding layer formed in a stripe pattern on the terminal electrode's surface, either by forming a Sn layer or creating a stripe form laser mark to enhance adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermocompression is used to connect the wire to the terminal electrode, then the wire connection is achieved, but coating film residue remains on the mounting face causing voids and cracks
Solution Approach 1:
The patent applies preliminary action by forming the easy bonding layer on the terminal electrode surface before the wire thermocompression connection process. This pre-formed layer prevents coating film residue from adhering to the mounting face during subsequent thermocompression, thereby avoiding voids and cracks while maintaining manufacturing efficiency.
Solution Approach 2:
The easy bonding layer acts as an intermediary substance between the terminal electrode and the coating film residue. It provides a surface that prevents the coating film from adhering to the mounting face, thereby mediating the interaction between the thermocompression process and the electrode surface to eliminate reliability issues.
2Ease of manufacture
If thermocompression heat is applied to connect the wire, then the wire is bonded, but the Sn layer melts and diminishes reducing adhesiveness
Solution Approach 1:
The patent changes the material parameter of the terminal electrode surface by forming an easy bonding layer with specific material properties (low melting point, high adhesiveness). This layer remains intact during thermocompression heat application, maintaining adhesiveness while enabling wire bonding through controlled parameter selection.
Solution Approach 2:
The easy bonding layer is preliminarily formed on the terminal electrode before thermocompression. This pre-formed protective layer prevents the Sn layer from melting and diminishing during the subsequent heat application, thereby preserving adhesiveness while achieving wire bonding.
3Object-affected harmful factors
If coating film is applied to the wire, then the wire is protected, but residue remains on the terminal electrode mounting face
Solution Approach 1:
The easy bonding layer serves as an intermediary surface that prevents coating film residue from adhering to the mounting face. It allows the wire coating to provide protection while the intermediary layer ensures the mounting face remains clean and free of residue.
Solution Approach 2:
The patent applies local quality by providing different surface properties to different parts of the terminal electrode. The easy bonding layer is specifically formed on the mounting face area to prevent residue adhesion, while other parts of the electrode maintain their original properties for their respective functions.
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 stripe form easy bonding layer significantly improves the adhesiveness between the terminal electrode and connecting members like solder, reducing void formation and crack occurrence, thereby enhancing bonding strength and reliability.
Implementation Method 1
A stripe form laser mark is formed to a surface of the terminal electrode connected with the lead of the wire. A residue of coating film generated when the lead of the wire is connected by thermocompression to the terminal electrode is almost completely removed by laser irradiation.
Implementation Method 2
an end part of a wire forming a coil is connected by thermocompression to a terminal electrode having a mounting face
Data Source
AI summary
To provide a coil device having high bonding strength and bonding reliability.The coil device 1 has a core member 10 having a winding core and a flange 12, a wire 32 wound around the winding core, and a terminal electrode 52 connected with a lead 32a of a wire 32 provided to the flange 12; and an easy bonding layer 70 is formed on the surface of the terminal electrode 52 connected with the lead 32a in a stripe form 70a. the stripe form each bonding layer 70a is formed as a laser mark 71. In the coil device 1, a residue of coating film 78 which may be generated when the lead 32a of the wire 32 is connected to the mounting part 65 of the terminal electrode 52 is removed by laser.