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About SMT patch processing online needle bed detector
Online testing ICT is a testing method to check the manufacturing defects and defective components by testing the electrical performance and electrical connections of online components. ICT is a contact detection technology, which has a strong fault diagnosis ability, so it is widely used. Place the SMA on a specially designed needle bed fixture. The spring test probe mounted on the fixture is in contact with the lead or test pad of the component. As it contacts all the networks on the board, all analog and digital devices can be tested individually. And can quickly diagnose bad devices.
In ICT, due to the long cycle of needle bed fixture production and program development, and the relatively high price, at the same time, due to the limitation of machining equipment CNC machine tools when processing the needle bed fixture, the test probe must be designed on a 2.54 mm or 1.27 mm grid, So that the minimum distance between the probes is 1.27 mm, so ICT is suitable for products with general assembly density and mass production.
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At present, there are two types of ICT instruments: one is Manufacturing Defect Analyzer (MDA), and the other is ICT0 MDA is actually a simplified form or early product, it can only be used for analog testing, and is mainly suitable for analog circuits. The test of the component board. MDA usually uses voltmeter, ammeter, ohmmeter and other instruments to complete the measurement, and through software and programs to control the entire measurement process, detectable defects such as whether the component is missing, whether the polarity is standard, resistance, capacitance, diode, triode Related errors, etc. Because it does not drive SMA, it does not have the actual function of testing digital devices. Its biggest advantage is fast programming, low cost, and quick test response. At present, electronic products have already entered the digital age, so MDA has basically withdrawn from the testing field. The function of ICT is much stronger than that of MDA. In addition to all the functions of MDA, ICT can also perform online testing of digital devices. ICT can detect almost all defects related to the manufacturing process, so it is now widely used.
SMT factory processing on the basic composition of ICT
The needle-bed online test system consists of five subsystems: computer control system, measurement subsystem, signal excitation subsystem, signal management, switch conversion system and test access fixture, as well as user interface and circuit components under test.
The computer control system includes computer hardware, various communication interfaces, test operation software modules, graphical user interfaces, peripherals, etc. The measurement subsystem is a collection of various program-controlled measurement instruments and auxiliary test modules in the online test system. It is a detection method for the circuit component under test in response to the excitation signal. Data comparison. The signal excitation subsystem is also a collection of program-controlled signal sources, such as power supplies, integrated signal generators, counters, etc. During testing, the excitation signal suitable for the test is automatically selected and loaded to the circuit component under test according to the programming control instructions.
SMT processing plant on SMT-QAS design
The switch conversion system mainly controls the system to automatically switch to the selected test channel according to the programming instructions, and plays the role of loading the excitation signal, connecting to the measurement subsystem, and connecting the test needle bed and probe. A good online test equipment should have a concise, easy-to-understand, intuitive, and easy-to-use graphical user interface. At present, the online test equipment has basically adopted a Windows operating system and a test debugging programming system. These devices can be programmed to select the appropriate test channel number according to the object under test through the graphical interface, while observing the excitation and response signal waveforms during the test.
