The Design And Implementation Of The Electronic Control Part Of Testfixture For Flexible Printed Circuit Board

In recent years, consumer electronic products develop in the direction of portable and miniaturization, which is inseparable with the rapid development of Flexible Printed Circuit(FPC in short) board. FPC, also known as “Soft Board”, can be bent or folded arbitrarily according to the spatial layout, which greatly reduces the size and weight of electronic products. FPC is most widely used in mobile terminals, especially as the popularity of 3G & 4G smart phones in China, the mobile phone market is very competitive, which requires much on the on-time shipments. Meanwhile, consumers have increasingly high quality requirements for electronic products. These two aspects make the customer expect highly on the delivery speed and assembly yield, therefore, the factory needs to improve the yield rate and shorten delivery time, and then the requirement on the development efficiency of FPC test fixture is getting higher and higher.The electronic control part of test fixture in this project design is basically “universal”, which greatly improves the development efficiency of FPC functional test fixture. It mainly contains five functional modules: LED test module, data acquisition module, trace test module, dome test module and LCD display module. LED test module can test LED color and brightness, which effectively solves the problem of LED test accuracy and the high development costs of using CCD fixture to test LED; data acquisition module is used to test the voltage and current of functional devices, the system uses 16 bit I2 C communication AD chip, which meets the high-end customer’s demand for high-precision testing. Trace test module is used to test the FPC open/short circuit, so the fixture sending to customer doesn’t need secondary development, which makes it keep consistency with the factory using the same fixture. Dome test module is used to test full keyboard phone, maximum 8X8 matrix keyboard, the added pneumatic control can use finger cylinder instead of manual pressing, automatic stripping instead of manual stripping, which improves the automation of testing. LCD display module is used to observe the test procedures and results of the system.This system design solves the currently existed problem of special fixture for special use in factory, improves the test accuracy, greatly shortens the development cycle of new fixtures, effectively realizes the recycling of scrapped fixtures, and reduces huge costs of fixture development for the company. This thesis firstly describes the background of subject and status of FPC testing industry, analyzes the practical difficulties the factory encountered and the weaknesses existed in FPC functional test, and then proposes targeted solutions. On this basis, it discusses the design process of electronic control part of test fixture, conducts software and hardware design on the overall structure and various functional modules of the system, and finally verifies the validity of each module through system performance test, and makes corresponding testing assessments.