In addition to the traditional electric materials such as nickel-chromium alloy (alloy wire and by the silk cloth into the metal), the new ceramic and electric conductive polymer composite system has begun to wider application.This is the core of electric material a thin layer of conductive coating.The film caused a certain resistance, screen printing or coating application of the method of printing or spraying will be attached to the appropriate substrate, connecting the membrane electrode-income and low-voltage current, heat immediately released from the membrane Out.This electric material processing convenient, pollution-free, safe and good, high-electric conversion efficiency, low power consumption, energy-saving significant, is a more ideal electric material, has wide application in many fields.

The main features of electric membrane Electric power is a film after the fever of translucent polyester film, the special conductive ink, metal closure,as printing, pressing in the film between two layers of polyester insulation, heating and objects were a good exchange of heat exposure.It has high thermal efficiency (electric heating system films the thermal efficiency of over 90 percent, than the electric furnace about energy-saving three to four times), its low temperature (in the case of boiling liquid, heating the film itself only higher than the temperature of liquid dozens ), The heat capacity of small, open heat off quickly, no open flame, heating of the film almost no space so that the apparatus abnormal light, water, acid and alkali-resistant and high mechanical strength.

Some of its own electric transparent membrane, such as attached to the transparent substrate (glass), the whole apparatus can be made transparent appliances. Various types of electric film, if the shape of its components, ceramics and electric conductive polymer composites of two categories.The former general from metal or metal oxides,glass and other low melting point of the latter by the conductivity of metal and non-metal or metal coated with particles of inorganic and organic polymer and other components. If the film processing and forming the temperature difference between the nature of the changes, the film can be divided into electric-dry at room temperature (that is, non-cross-linked), at room temperature cross-linking, the temperature curing type of high-temperature sintering (conductive ceramics), four

According to film in the electric conductive filler material and resin link nature, form, structure and composition of different, the film also features agreater difference. Conducting the general nature of packing, shape, size and the film in the percentage of such factors, the impact of electric film forming properties and heating performance. Polymer materials and link the different types and structure of the cured coating of dry conditions and heat resistance of the film and its place in the substrate, and so on have a direct impact on adhesion. Some of the coating can be dried at room temperature, and some are at room temperature curing cross-linked, and some can only be cured through heating film, but the level of heating curing temperature and the length of time will also resin nature
and structure of the different Different.

Electrothermal film is a complex, it uses a conductive filler, bonding materials, additives and solvents, and other components of the conductive paste, by spraying or screen printing, construction on the substrate, and then dry cured from.Under different conditions dry curing the electric film, its heatresistance is not the same. Electric dry at room temperature only slightly higher than the film in general following the use of human body temperature, and cured at room temperature under the electric heat-resistant properties to a number of films, usually in less than 100 ℃ long-term use.

If you need more than 100 ℃ in the use of the electric film, its bonding material should be used often thermosetting phenolic resin, epoxy or silicone resin.Most electric power heating membrane, the temperature rise, the membrane resistance little changed, heating time extension, the film fever temperature will continue to increase, constant temperature down to it, to be applied temperature controller, and was referred to as non-temperature-controlled - Electric membrane.Some electric and non-film-controlled temperature-On the contrary, when the film connected to electric power, the beginning stage of the resistance film some changes in temperature rise process, the film reached a certain temperature once a certain value, the resistance suddenly increased to infinity, so that Films on a constant surface temperature in this state.

This has its own temperature control function of temperature-controlled electric film called membrane-typeelectric.Electric heat resistance of the film good or bad, not only by restricting the film itself, but also with electric film in molding what kind of substrate is also relevant. If adopted by the substrate 2mm thick polypropylene plates, in order to increase the coating on the substrate adhesion to the polypropylene surface pretreatment.Coarse sand blasting method is first, after using plasma technology oxidation process. After pretreatment of the substrate, coating adhesion although increased, but Polypropylene is a thermoplastic, their heat resistance is not too good, when the electric heat to 110 ℃ film, a polypropylene plate heat Deformation, the center of stress concentration, first of all, there is depression.Because of the electric membrane expansion coefficient of small and large expansion coefficient of the substrate, the deformation of the fever to have electric membrane side bending depression, this electric deformation will damage film.

Therefore, the relatively good substrate expansion coefficient should be small, rigid good insulating material, such as phenolic laminate, glass or inorganic materials such as steel.The use of inorganic glass substrate for electric film, the film later in the 140 ℃ under heating curing 2h, cooled to room temperature and fever tests done warming up, we can see that even if the film's surface temperature as high as 160 ℃, film will not By the slightest damage.Electrothermal film is a new type of heating materials, because it has produced convenient, energy-saving in energy, supplies low, low price, non-polluting, and many other features, in many areas are widely used.

For example, in the industrial, agricultural, medical, electronic and electrical appliances, building materials, daily life in areas such as electric film has been applied to various pipelines and storage tanks, equipment, greenhouse nursery,food processing, such as the required heating, insulation, Of snow, antifreeze, and so on. In aircraft and high-rise windows, such as the anti-Lu and defrosting, temperature and show paint match display devices, the heating insulation of housing, household insulation Cup warm kettle heating and insulation, and other applications is also very extensive. For example, the electric heating film as a way of controllability

of strong (according to every room needs at room temperature control system and the opening to meet the individual needs),infrared electromagnetic waves through the direct infrared heat, no air circulation, Will cause dusty, and the advantages of low investment costs. Have now developed a smart electric film, which use high-tech electric film, in the electric field can be stimulated, can produce beneficial to the human body specific wavelength infrared.
The use of electric film can effectively avoid the impact of electromagnetic fields on the human body and the interference of household appliances.In recent years the rise of electric film will be used for electric appliances such as electric Cup, Dianhuo Guo, electric heating, Irons, water heaters, market prospects are very good. Screen Printing electric film production

In addition to the quality of electric membrane and the composition of the film, the film forming process is also an important factor. More commonly used method of spraying law and screen printing method.Because of the coating spray area, coating thickness, thickness control difficulties, the same coating thickness of different parts of the error, and therefore not easy to reach fever temperature uniform.And the use of screen printing, coating thickness, coating all parts of the same thickness of error small, relatively uniform temperature fever, is an ideal way process. The use of electric film, in the membrane attached electrodes is indispensable The electrodes can be processed steel foil paste boost, but generally use screen printing conductive silver paste generation.If only lead of the welding point of view, the paste of copper foil for good.However, this process is both complex and paste trouble, poor reliability. The electric screen printing with the membrane electrode made of their good quality, especially in recent years the use of new development of the heat resistance of the fine silver paste,use screen printing electrodes after heating curing, the welding wire has been very solid. This network of high-quality printed electrode, operations and good, safe, reliable, the process is more commonly used methods.Although the electric screen printing film overall effect, and all parts of the membrane fever uniform.However, the current conductive paste, use screen printing electric film, some processes would also like to pay great attention to the operations, technology still needs to be strengthened.

In case of India in the washing net, the choice of solvents, such as size of the adjustment has given strict requirements. In addition, the preparation of conductive paste, whether the choice of the number of heads of the conductive particles to fill, and so far there is no uniform standard. To fill the same, the smaller the particle size, surface area is, the better conductivity of the printing quality is also desirable.However, the smaller the size, heat resistance worse, under the conditions of heating in the thermal stability there will be problems.This packing from the electric system in the film often can not withstand the test of long-term warming fever.Therefore, these must be fully observed in the application of summing up, to find the best solution. Conductive coating fill in the dispersion of state on electric heating properties of film can not be ignored. Decentralized state, and the film Fever uniform, but do not. A coating to prevent the fill material in the settlement, conductive paste in the production process in the choice of what kind of surface-active agent is particularly important. Especially on the metal packing density, screen printing, the greater the thickness of the coating, the coating dry filler particles in the process of curing the easier it is settlement, the settlement filler particles, the film lower than the top of the particle packing density Greater, so the thickness of the film than the thickness of small measure to lower the volume resistance. If the thick coating of the electric section of the film to do careful observation, you can immediately see that the lower deck of the film distribution density of particles in a greater difference. On the same coating, the thickness of each part is uneven, thin coating of the local resistance values high, thick low value of local resistance.When the coating on the uneven power, the thin film of the surrounding temperature is too high, the electrical circuit can be easily burned.Use screen printing of the electric membrane, can be considered a uniform.

If electric heating surface temperature of 60 ℃, can detect the different parts of the film in the temperature difference between 5 ~ 10 ℃, which are allowed in the application of electric film also shows a more uniform thickness. To improve quality, to make it more stable, screen printing, metal slurry on the concentration of the printing ink in size to strict controls. To non-temperature-controlled electric film, the temperature control sensors installed in any part of the electric film is also very important thing, if the installation of inappropriate sites, it is impossible to accurately reflect the electric membrane surface temperature.In order to make the film electric heat evenly spread, the thermal conductivity of a good choice for metal plates to the substrate is useful.To this end, the film to give electric power fever, it is necessary to set up electrode. This choice of electrode material, made what shape, line-how to connect, temperature control is how some highly technical work, and in order to prevent excessive temperature rise, switch settings, insurance, and other parts of the installation are key.If you want to get high-temperature conditions for the use of the electric film, but also in flexible materials can be used, it is necessary to choose suitable financial statements of the polymer material and heat resistance good substrate, the size of the particle size also fill the

need for further Of the study.

Author: Qicheng sources of information: Screen Printing Industry