The coil-winding process is the main part of the production process of an electromagnetic micro-coil. This process involves the twisting or winding of a very thin wire around a core. This thin wire is known as the ultra-fine wire that has a diameter of approximately 56 AWG. Manufacturers can wind the ultra-fine wires differently to offer different shapes. Primarily, these wires go through an isolation process for providing protection to the wires against external heating. Then, the manufacturers wind the isolated wire around a central pin or core.
Because of this winding process, an electromagnetic induction gets generated within the micro-coil. Insulated copper wires are the perfect choice for the micro-coil winding process. However, depending on the application area and customer need, several other temperature-resistant materials can be useful.
The Shape of the Micro-Coils:
The shape of the micro-coil varies based on the needs of the customers and the application area. The different shape produces dissimilar electrical values. Therefore, the manufacturers first consider the required electrical value of the coil and then set the inner and outer dimensions to properly shape the coil. The micro-coils can look different due to various shapes, such as elliptical, circular, and rectangular.
Coil Winding Process for Biomedical Sensors:
When it comes to producing medical-grade micro-coils for sensors, size becomes a very important parameter during the winding process. To send the sensors to different difficult body regions, the tiny size of the coil is essential. For instance, if you need to insert a micro-coil into the vein, you will require a 0.8 mm coil. Therefore, highly specialized equipment is required to prepare coils maintaining this tiny size.
Even though most micro-coils have a core, they can also be self-bounded or coreless. If you need a rectangular-shaped or cylindrical-shaped coil, then the manufacturers will use rectangular or cylindrical support during the winding process. However, they will remove the support once the process is completed. Similarly, they can produce coreless coils by removing the core after the winding process. To get rid of the size constraint, manufacturers also use wires of 8 microns in diameter. These ultra-fine wires are suitable for the production of coils in medical applications.
How to Manufacture the Micro-Coils?
When the manufacturers are developing micro-coils for medical purposes, they should have
- A great knowledge of the coil winding process, and
- The capability to use specialized equipment during the winding process.
As the requirements of the customers differ depending on the application area, to fulfil their needs, you can not use the machinery that is available n the market. Instead, you will have to design and develop your equipment. From the soldering method to wire terminals, in every step of the manufacturing process, you will have to use built-in-house and specialized machinery.
Ultra-fin wires are essential for preparing medical coils due to different reasons, such as to produce the inductive components and build connectivity within the devices. Although the tiny size of the wire is useful for medical devices, this leads to several challenges for the manufacturers. Therefore, to work with these wires effectively, manufacturers will need various innovative technologies.
An ultra-fine wire (9 microns o 59 AWG or 0.00035 inches) can be five to ten times smaller in diameter in comparison to human hair. Despite this tiny size, manufacturers need to maintain the tolerance requirements in the final products. Therefore, to control the tension and position of the wire, they should use custom-made machinery and state-of-the-art micro-motion technology during the winding process.
Thermal Compression Bonding Technology:
During the coil winding process, sometimes, it is essential to build a connection between two different ultra-fine wires. Connecting two tiny wires is a great challenge for the manufacturers. This is because the heat-based traditional methods can destroy the wires, instead of connecting them. Therefore, we can not use traditional soldering and welding methods for this purpose. The best remedy for this connectivity issue is the thermal compression bonding technology. This is an effective and reliable method to join ultra-fine wires without damaging the wires. This method is not only useful for similar types of ultra-fine wires but also effective to connect a wire with another wire of dissimilar diameter and material. Thermal compression bonding technology helps to build the most reliable and corrosion-free joints during the coil winding process. Therefore, this technology has a great role in overcoming the challenges of the coil winding process.