The materials of thick film MCH electric heating element mainly include: carrier material, electrode material, resistance material and protective layer material, among which the resistive material determining product function is the most important. Based on previous experience in making other thick film products, the following materials are finally determined after many experiments:
1) Carrier material: A1203 ceramic substrate suitable for large-scale production of our company is selected. With good insulation, thermal conductivity and physical strength, this material is one of the mature carrier materials in thick film product processing.
2) Electrode paste, select the appropriate silver/palladium/platinum ratio and formula, the material has good electrical conductivity, solderability, resistivity, adhesion, rheological property and thixotropy.
3) Resistance material: oxidized nail series resistance paste containing glass is selected. The paste has high stability and consistency of resistance value, small TCR and small temperature drift, which can achieve good stability of resistance value in practical use.
4) Protective layer paste, the main component is glass protective layer paste, good insulation performance, has a good protective effect on the electrode layer.
After analyzing the similar products at home and abroad and combining with the production experience of the original thick film type components, the production process of thick film type MCH electric heating circuit is summarized as follows:
Making mesh: one electrode layer printing - drying, electrode layer sintering - resistance layer printing - drying → resistance layer sintering - protection layer printing → drying → protection layer sintering - laser resistance adjustment - resistance value testing → packaging.
3-Product feature testing
After the production of the samples, 5 pieces of products were taken for testing according to the requirements of the technical indicators. From the results, the samples met the design requirements and could meet the needs of the market.
4-Trial production results
Through the joint efforts of product project developers and related personnel, the development of thick film MCH electric heating elements has been completed, the product performance has reached the design requirements, and a feasible production process has been developed, which can be used for mass production.