Before the production of thick film heating body, the need for a pretreatment of the stainless steel substrate, remove the oil, impurities, fingerprints, etc. on the stainless steel substrate, in contact with the substrate, should wear latex gloves. Secondly also need to screen screen plate, screen plate production process see Figure 2, first according to the size parameters we want to screen, select screen materials, screen materials polyester, polyester, stainless steel wire, etc., and then in accordance with the number of mesh stretch network. After the stretch net is completed, the photosensitive adhesive is coated, the thickness of the photosensitive adhesive also needs to be selected according to the parameters of the paste, after drying, exposure development Preprocessing after entering the screen printing, printing paste order is the first printing dielectric layer, and then the printing conductor, if need to printing PT: protect the resistance, in the printing after the conductor resistance PTC protection (IPTC resistance is used to detect the surface temperature), then printing and heat resistance, and at last the printing surface medium, general surface medium and unique green medium is the same size, the thickness of the printing, according to the size specification for general insulation layer thickness are s0 meters, heat resistance at 20 microns, conductor material in more than 10 microns.Printing after drying and sintering, and each has a different drying and sintering temperature and time have differences, all these need according to the selected parameters of the thick liquid material, the following is ESL 4924 models of dielectric paste sintering curve, process must be conducted in strict accordance with the size of the sintering curve (see figure 3), otherwise it will affect the performance of the heating element.
After the completion of sintering, it is necessary to carry out appearance inspection to detect the sintered defective products, such as bubbles and voids. Then the electrical performance is tested, including insulation resistance, withstand voltage, leakage current, resistance value and so on.
According to household appliances, insulation resistance of heating elements shall be more than 100M2, withstand voltage 1500V/Imin/10mA, and leakage current shall be less than 0.75mA.