Kapton is one of the first-choice materials for insulating electrical wires in temperature-critical applications. It can be integrated into conventional wiring designs where single or multi-strand conductors – typically copper – are encapsulated in a protective insulating sheath. In this case, the insulator is a patented polyimide with ties to aviation and space exploration, exhibiting exceptional thermodynamic stability combined with superior dielectric performance in vacuum conditions.
At Allectra, we develop Kapton-insulated wires in a wide range of configurations and formats. Alongside traditional types for standard signal transmission, we can offer coaxial cables and flexible ribbon harnesses for low-loss signal transmission in high-vacuum and ultra-high vacuum (HV/UHV) environments. Among our many precision, Kapton-insulated wire products are a selection of Kapton thermocouples for temperature-critical vacuum processes.
We have explored Kapton wires extensively in recent articles. This week, we want to put the spotlight on our Kapton thermocouples for temperature sensing in HV/UHV settings.
What are Thermocouples?
A thermocouple is a form of temperature sensor based on a cable comprising two different metallic conductors, which are fused together at one end to form a junction. This junction is exposed to the sensing environment. Readings from inside the chamber are transmitted to an external indicator via a hermetically-sealed feedthrough, enabling real-time continuous monitoring of in-vacuum temperatures.
Thermocouples do not read temperature directly. Rather, they allow sophisticated software to calculate process temperatures as a function of charge separation, or electromotive force (EMF). This is highly dependent upon material combinations. Type K thermocouples are comprised of Chromel (90% nickel & 10% chromium alloy) and Alumel (95% nickel, 2% aluminium, 2% manganese & 1% silicon alloy) wires and are one of the most common thermocouple wire pairs.
Type K and Type N Kapton Thermocouples
The alumel-chromel (type K) pairing is popular for several reasons: it is accurate and reliable across a wide temperature range and is relatively inexpensive. Type K thermocouples are subsequently employed in a choice of tough working environments and allow temperature measurements from -200°C up +1250°C.
Type K thermocouples are compatible with an array of feedthroughs and measuring instruments, with superb performance across a wide temperature range, they are ideal for temperature sensing in sectors ranging from alternative energy research to cutting-edge surface science.
Type N thermocouple wires offer high stability over time with temperature range measurements from -250°C up to 1300°C max.
At Allectra, we supply Kapton-insulated Type K & N thermocouples for temperature-critical vacuum processing. Please note that Kapton can withstand a max. temperature of +300°C. We now offer new 301-Type K & N Kapton-insulated thermocouple wires that are both UHV compatible & radiation hard / resistant.