The Study Of Four-Probe’s PCB Test System

PCB for3COM electronic products and high safety performance requirements ofautomotive use PCB, medical equipment, etc., more and more customers demands for microresistance test. this is because in this type of PCB, that line is not only wire or signal lines atthe same time, the line resistance changes will cause delay and attenuation of signals, causefunctional problems. such as hole, hole copper thin, defects such as line gap will affectproduct safety in use. And the traditional electrical measuring method already can’t adapt tosuch a tiny resistance test requirements. Therefore in the process of PCB production provide aresistance test that can detect minute is very important.Four-point probe measurement method, is a classic test of the PCB electric loggingmethod, it can greatly reduce the contact resistance in the test and the loop resistance, andeasy, suitability is strong, and have enough high testing precision, the technology bysemiconductor manufacturers at home and abroad since its birth one of the most widely usedmeans of monitoring, with the rapid development of electronic technology, semiconductormanufacturing and production of integrated circuits technology attaches great importance toby the governments, the development of efficient four point probe test system is imperative.This topic research the four point probe PCB electric machine test measurement andcontrol system, can realize in the process of PCB production of hole, hole copper thin, linegap detection such as small resistance value changes. Measurement of system control unitadopt modular design, the system of each switch unit as many as128points, test speed, largecapacity, and convenient extension. Secondly, this paper also introduces the design of themeasurement control unit in detail, and in view of the measurement circuit module, excitationsource module and the principle of switch matrix unit were analyzed, and the design ofhardware circuit is given. Finally, in view of the system software measurement control unit ispresented and the overall scheme of the software design of switch matrix, and presents ameasurement control unit and switch matrix unit detailed design of the software modules.Notch, the thesis starts from studying the principle of four point probe, in-depth study offour point probe test method and the suitable conditions, and combined with the currentmature technology and characteristics of the existing according to the theory of in-line four probe method, PC as the core, designed a four point probe PCB electric machine testmeasurement and control system.