Insulation and passivation films
Polyimide materials are lightweight, flexible, resistant to heat and chemicals. Therefore, they are used in the electronics industry for flexible cables and as an insulating film on magnet wire. For example, in a laptop computer, the cable that connects the main logic board to the display (which must flex every time the laptop is opened or closed) is often a polyimide base with copper conductors. Examples of polyimide films include Apical,
Kapton, UPILEX, VTEC PI, Norton TH and Kaptrex.
Structure of poly-oxydiphenylene-pyromellitimide, "Kapton".
Polyimide is used to coat optical fibers for medical or high temperature applications.
An additional use of polyimide resin is as an insulating and passivation. Layer in the manufacture of digital semiconductor and MEMS chips. The polyimide layers have good mechanical elongation and tensile strength, which also helps the adhesion between the polyimide layers or between polyimide layer and deposited metal layer. The minimum interaction between the gold film and the polyimide film, coupled with high temperature stability of the polyimide film, results in a system that provides reliable insulation when subjected to various types of environmental stresses.
Multi-layer insulation used on spacecraft is usually made of polyimide coated with thin layers of aluminum. The gold-like material often seen on the outside of spacecraft is actually single aluminized polyimide, with the single layer of aluminum facing in. The yellowish-brown polyimide gives the surface its gold-like color.
Polyimide powder can be used to produce parts and shapes by sintering technologies (hot compression molding, direct forming, and isostatic pressing). Because of their high mechanical stability even at elevated temperatures they are used as bushings, bearings, sockets or constructive parts in demanding applications. To improve tribological properties, compounds with solid lubricants like graphite, PTFE, or molybdenum sulfide are common. Polyimide parts and shapes include P84 NT, VTEC PI, Meldin,Vespel, and Plavis.
In coal-fired power plants, waste incinerators, or cement plants, polyimide fibres are used to filter hot gases. In this application, a polyimide needle felt separates dust and particulate matter from the exhaust gas.
Polyimide is also the most common material used for the reverse osmotic film in purification of water, or the concentration of dilute materials from water, such as maple syrup production.