Keyword: PCB, PCB bare board, PCB assembly, PCB assembly design
printed circuit board assembly test refers to the PCB after installation components for the electrical and physical tests. Affect board assembly testing difficulties, its detection method than PCB bare board testing much more complex. pair assembly testability design should include system testability issues . system testability feature requests should be submitted to the whole overall design concept for review. printed board assembly testability must be designed integration, testing and maintenance of the integrity of the compatible .
PCB assembly design for testability before the start should be the same printed circuit board manufacturing, installation , and testing and other technical staff for review . Ensure testability results. The review shall involve visual level circuit pattern , the installation density , test methods of operation, testing division of the region , special testing requirements and test norms printed circuit board. PCB assembly level test There are two main types, one is to have the assembly of electrical function independent functional testing , the assembly is applied to the input of a predetermined excitation signal by monitoring the output terminal to confirm the results of the design PCB and installation correct another test is detected optically and assembly line testing , optical testing no explicit constraints on the design , as long as there is a certain degree of visibility printed circuit board and hold circuit can be detected , the method is mainly check the installation and welding quality online test limits for PCB test points shall be designed primarily in the coordinate grid test needle bed with matching place and can weld surface test , if the test with flying , then we must ensure that the test point at the coordinate grid on printed circuit board, but also in the layout can maintain sufficient space probes ( flying ) hit the contact points to be tested , flying tests on both sides of the board , the main test assembly and welding quality and processing component damage.
Commonly used test methods manual testing and automated test equipment PCB. Artificial test multimeter, digital voltmeter, insulation resistance tester, and other equipment for testing , low efficiency, records and data processing complex, and subject to the restrictions packing density , miniaturization of high density printed circuit board assembly is difficult to rely on manual testing. automated detection equipment with high precision , good reliability, repeatability, high efficiency and some instrument also has an automatic judgment , record, display and automatic fault analysis. Automated testing techniques are commonly used automated optical inspection (AOD), Automated X-ray measurement blocks (AX I), online testing (ICT) and functional testing , etc. In the PCB should be considered when designing printed circuit board assembly test compatibility resistance, if the test method is not considered necessary tests and rules even when the electrical machine with good testability circuit on the printed board assembly is relatively difficult to test , such as a test point location , size, and pitch of the test point with test probe or needle bed matching problem. online testing electrical conditions set problems and prevent damage to the test on the components PCB, etc. are to be considered and testability problems.
