Precision insulated wires are an often overlooked aspect of tough manufacturing and research environments, particularly those involving high vacuum and ultra-high vacuum (HV/UHV) pressure regimes. Standard copper wires with plastic sheathing are simply unsuitable for conditions associated with vacuum processing. Even comparatively low-pressure regimes (>10-4 mbar), often referred to as process vacuum conditions, require fine wire solutions with carefully selected polymeric insulation.
HV/UHV Kapton Insulated Wire: Performance Properties
When the vacuum regime is extended by several orders of magnitude (>10-9 mbar), specialist cabling solutions like rigid Kapton wires are required. The reason for this is twofold. Firstly, the conductive wiring and encapsulating insulation must be HV/UHV compatible with high-performance at in-process pressures while exhibiting negligible outgassing characteristics. Secondly, connectors and wires must contend with a range of additional process conditions (temperature, radiation, etc.) that could affect performance and ultimately the lifespan of the product.
Kapton wires are routinely employed in HV/UHV processes for their tandem electromechanical performance capabilities. Using a choice of conductors and cabling configurations, Kapton wires utilize a proprietary, space-age polyimide as a sheathing material. Without the right insulator, electrical signals transmitted by HV/UHV cables may be distorted or subject to electromagnetic interference. Where Kapton excels is in its ability to isolate electrical signals across an extremely wide temperature range, due to its unprecedented thermodynamic stability.
Kapton Wire Configurations & Applications
As mentioned, there is a wide range of Kapton wires available for HV/UHV processing. They are typically composed of copper wire harnesses that are either dipped or wrapped in a polyimide sheath. Though there are various formats available, there are five primary types of Kapton wire solutions prescribed for HV/UHV applications:
- Coaxial cables
- Shielded, twisted pairs/ribbon cable
- Proprietary Caburn UHV®
We discussed how the flexibility of Kapton wires is routinely used as a selling point. Multi-strand, Kapton wires offer enhanced flexibility thus exceptional performance as general-purpose cabling for signaling and sensing in vacuum environments. Single -strand wires are more rigid than multi-strand wires and you can bend them but they will hold their shape.
Rigid Kapton wires based on coaxial cables, twisted pairs, and ribbon cables are typically employed in HV/UHV environments with more stringent operating conditions. Cryogenic applications, where in-process temperatures may drop as low as 77 kelvin (K), for instance, typically utilize a specialty form of Kapton wire based on Manganin® conductors. Shielded ribbon harnesses with Kapton insulation can actuate motors in-vacuum with low signal loss and negligible interference.
Rigid Kapton Wires from Allectra
Allectra is one of the leading manufacturers of HV/UHV components for processing and research applications. We supply a broad range of Kapton wire solutions for all manner of vacuum environments. Contact a member of the Allectra team today for more information about our precision wiring range.
* Caburn UHV® is a registered trademark owned by Dr. Michael Holmes, at Allectra