The Research And Design Of PCBA Automatic In-Circuit Test System Based On The FPGA

PCBA(Printed Circuit Board Assembly)is an integral part of the development and production of electronic system,its quality affects the performance of the system directly,and to test the Circuit Board is related to the quality of the electronic system and an important part of the production cycle.In batch production process,because of the equipment?technology and the operator of the various possible factors,can't guarantee the welding on the circuit board components working normally.Automatic on-line testing system will load the excitation signal measured components on PCBA,detecting output response to judge whether the onboard components fails,completing the component level testing.This article first analyzes the automatic online testing system of electrical isolation principle,and introduces the common components resistor,capacitor,inductor,diode,triode and operational amplifiers online testing principle,and design the different components of the hardware circuit;Analysis of agilent patented technology,through the chip pin coupling capacitance for chip welding quality,analyzes the test principle and test small capacitance of the hardware circuit is designed.Then according to the requirements of the system design and the software and hardware design scheme,design the main control board,AC signal board,DC signal board,switch board and motherboard.In addition to the motherboard,each board use a piece of FPGA as controller,form two levels of FPGA architecture,main control board FPGA as master,signal board and switch board FPGA as slave controller,automatic complete system of switch controlling,signal generator,data acquisition and transmission.In salve machine sofeware as modular design,the main controller FPGA building a Nios II embedded core based on SOPC technology,using the C programming language comply USB2.0 communication with computer,system self-testing,data acquisition and slave FPGA controlled.At the same time on the master board reserved boundary scan interface chip,facilitate the realization of the follow-up system boundary scan function and upgrade,to solve the traditional online test system of large scale digital integrated circuit test board,improve the test coverage of the entire system.Signal boad FPGA use VerilogHDL hardware description language programming,controlling the incentives needed to generate thetest signal source and signal conditioning acquisition.AC signal is based on direct digital frequency synthesis technology(DDS),DC voltage and current signal is based on D/A,and the combination of analog switch.Switch board is responsible for testing the channel,depending on the test command to switch the corresponding test channel and the discharge channel and design and functional test system(FCT)isolated channels,to facilitate complex online testing system and functional test systems share a fixture,completed component level testing and board-level testing,improving efficiency and cost saving.Finally,this paper builds the prototype testing,and completes system function basically.Acrossing to the experimental data,complete systematic error analysis and compensation,and summarise the research work on and outlook of this paper.