Development Of Extended Measurement System Of Laser Trimming Machine

With the rapid development of information technology, all kinds of electronic productsare becoming smaller and smaller, and this trend cannot be reversed. The thick-film hybridIC plays an important part to miniaturize electronic devices. But large error of the value ofthick-film resistance will appear, due to its manufacture technique. So the thick-filmresistance must be adjusted to meet the required precision. And the laser trimming machineis an ideal automation processing equipment to do this work.This project aims at the actuality that the existing laser trimming machine cannotsatisfied the demand of milliohm resistor trimming and in-circuit network resistor trimming,so the extended measurement system of laser trimming machine was developed. Thissystem consists of milliohm resistor extended measurement instrument and in-circuitnetwork resistor extended measurement instrument. This paper does some research anddesign works around above-mentioned instruments as follows:At first, this paper analyzes the basic methods and principles of resistancemeasurement. And the Kelvin4-wire method was chosen as the test method for this project.Then the technical solutions and total scheme of extended measurement system were putforward. Secondly, the paper analyzes the basic principles of constant current source andgive out the design plan of program-controlled constant current source. Then the hardwaredesign, heat dissipation design and software design were also provided. Thirdly, the papercompares some resistance isolation schemes which based on voltage follow circuit andfinished the hardware design and software design. This system realized the isolation fornetwork resistance successfully. At the end of the paper, the design of extendedmeasurement system is summarized.