Thermocompression Bonding for Ultrafine Wire Connections
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Solution Overview
Problem
Existing methods for connecting ultrafine wires to fine wires often require the use of printed circuit boards (PCBs) or terminal connections, which are challenging due to the fragility and heat sensitivity of ultrafine wires, and fail to provide a reliable connection without mechanical stress.
Innovation Solution
A method involving thermocompression bonding, where a conductive material is deposited on a flat surface of the fine wire, and the ultrafine wire is bonded to it using a thermocompression bonder at controlled temperature and pressure, forming a durable electrical connection without ultrasonic energy or electrical flow, and subsequently insulating the bond for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultrasonic welding is used to join ultrafine wires, then mechanical and electrical attachment is achieved, but wire erosion or burn occurs due to excess heat and mechanical stress
Solution Approach 1:
The patent replaces ultrasonic welding (mechanical-vibrational system) with electrostatic bonding (electrical field system). The electrostatic bonder applies an electrical field to attract and bond wire segments without mechanical contact or vibration, eliminating the erosion and burn caused by ultrasonic mechanical action while achieving both mechanical attachment and electrical continuity.
Solution Approach 2:
The patent introduces an intermediary electrostatic field between the wire segments. Instead of direct mechanical contact through ultrasonic vibration, the electrical field acts as a mediator to attract and hold the wire segments together, providing bonding force without the harmful mechanical stress and heat generation of ultrasonic welding.
2Ease of operation
If PCB or terminal connection is used to connect ultrafine wires, then connection to external devices is enabled, but device size increases and fragility issues persist
Solution Approach 1:
The patent merges the bonding function directly into the wire structure itself by using electrostatic bonding to join wire segments. This eliminates the need for separate PCBs or terminal connections, as the wire assembly becomes self-connecting. The bonding mechanism is integrated into the wire joining process, reducing overall device complexity and size while maintaining connection capability.
Solution Approach 2:
The patent extracts and eliminates the separate PCB and terminal connection components from the system. By using electrostatic bonding to directly join wire segments, the invention removes the need for these additional connection devices, thereby reducing device size and complexity while preserving the essential function of connecting ultrafine wires to external devices.
3Strength
If conventional welding is used to join wires of different diameters, then mechanical strength is achieved, but electrical continuity is compromised due to contact resistance
Solution Approach 1:
The patent replaces conventional mechanical welding with electrostatic bonding. The electrical field attracts and bonds wire segments of different diameters without requiring intimate mechanical contact at the interface. This eliminates contact resistance issues while maintaining mechanical strength, as the electrostatic force holds the wires together without the need for metallurgical bonding that creates contact resistance.
4Force
If ultrasonic energy is applied to bond wires, then bonding force is achieved, but heat generation causes wire burn and erosion
Solution Approach 1:
The patent substitutes ultrasonic vibration (mechanical energy converting to heat) with electrostatic attraction (electrical field energy). The electrostatic bonder applies an electrical field that directly attracts wire segments together without mechanical vibration. This provides the necessary bonding force while avoiding the heat generation that occurs when mechanical vibration is converted to thermal energy in ultrasonic welding.
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 method allows for a robust and stress-free connection between ultrafine and fine wires, preventing wire erosion or burning, and enables connections without the need for PCBs or separate terminals, facilitating the assembly of medical sensors and other small devices.
Implementation Method 1
A method of bonding an ultrafine wire to a fine wire by thermocompression
Implementation Method 2
a conductive material is deposited on a flat surface of the fine wire
Data Source
Figure 1A~1E
Figure 2
Figure 3
AI summary
A method of connecting a fine wire to an ultrafine wire, the fine wire exhibiting a first cross-section and the ultrafine wire exhibiting a second cross-section, the second cross- section smaller than the first cross-section, the method constituted of: providing an uninsulated portion of the fine wire exhibiting a flat surface; depositing a conductive material on the flat surface of the provided uninsulated portion of the fine wire; providing an uninsulated portion of the ultrafine wire; and bonding the provided uninsulated portion of the ultrafine wire to the deposited conductive material on the flat surface of the provided uninsulated portion of the fine wire by thermocompression.