| With the rapid development of advanced technology such as industrial automation,intelligent control and Internet of Things,discrete component is also moving forward to keep pace with the latest technology trends of high-density surface mount and integrated circuit in electronic information industry.Due to the advantages like small size,high precision and low temperature drift,thin film chip resistors are now widely applied in military and civilian fields such as electronic countermeasures,radar communication system and consumer electronics.Foreign companies have begun to produce thin film chip resistors several years ago,but only a few Chinese companies are capable of producing the same resistors.Moreover,compared with the technical level,series and categories of the products provided by foreign counterparts,a large gap still exists.The organization that the author works for has already developed some types of thin film chip resistors.However,the lack of reliable and stable preparation process of thin film greatly restricts the performance index of resistor.Therefore,it is necessary to develop and optimize the preparation process of thin film much faster,and finally build a reliable and stable production line.On this basis,relevant researches is conducted.In accordance with engineering practice and relevant theories of thin film chip resistors,the present study first drew lessons from advanced thin film sputtering technology and laser trimming technology worldwide.By means of material selection,key process development,optimal design of process parameters and a range of key process tests,it is intended to improve the preparation process of thin film and the reliability and stability of thin film chip resistors in the organization,eventually reach 10Ω to 3KΩ resistance range,the resistance deviation of each batch is less than ±20%,-10ppm/℃≤TCR≤+10ppm/℃.Therefore,the present study was conducted from the following three aspects to develop the key preparation process of thin film and optimize the design of process parameters for thin film chip resistors.1.The effects of sputtering power and sputtering time on film performance is investigated.It is thus proposed to develop the sputtering process of thin film and determine its optimal parameters based on the optimized sputtering process of thick film.The effects of screen-grid voltage and main ion beam on the deposition rate,uniformity,compactness and adhesive force of thin film is investigated to develop and optimize the sputtering process.The effects of surface roughness and cleanliness of ceramic substrate on the formation of thin film were investigated to propose the optimal parameters for surface roughness and cleanliness.2.The effects of the uniformity of heat treatment temperature on the resistance of thin film and the uniformity of temperature coefficient of resistance is investigated to explore the optimal heat treatment zone.Heat treatment test was performed to investigate the effects of heat treatment time on the consistency of resistance of thin film and its resistance to electrical stress and environmental stress,so as to develop and optimize the heat treatment process.3.The effects of the type of cutting,laser power and spot size on the resistance tolerance of thin film during laser trimming is investigated.By solving technical difficulties in resistor trimming and studying the impact of subsequent procedure on resistance tolerance,a new type of laser trimming technology based on S-shaped cutting and the combination of coarse tuning and fine tuning was finally invented. |
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