The board circuit test technology appeared in about 1960, the plated through hole (PTH) printed circuit board was invented and applied in batches. This technology mainly used single-sided printed circuit board connection and dielectric withstand voltage peak. That means to perform "bare board test". In the 1970s, the bare-board electrical connectivity test technology was gradually transferred to the circuit interconnection test of more important circuit components.
With the advancement of circuit assembly technology, the demand for PCB electronic products is growing rapidly. Therefore, It is the most important focus for electronic assembly process and quality engineer about how to accurately detect the SMA of the PCB assembly components, such as the knowability of the component or product assembly quality, the measurability, the degree of process control, etc. And further research is carried out and an automatic detection technology and equipment for circuit assembly boards such as online testing has been appeared. Especially under the support of computer hardware and software, network communication, instrument bus, test and measurement technology, the SMA detection system has also made a big leap. The current SMA detection has focused on the self-testing, assembly and soldering process structure testing and process control technology of circuit and chip circuits, and presents in the direction of high-precision, high-speed, fault statistical analysis, network, remote diagnosis, virtual test, etc.
The assembled component detection content. After the surface assembly is completed, the final quality inspection of the surface assembly component is required, and the detection contents include the following aspects. Solder joint quality, such as bridging, virtual soldering, open circuit, short circuit, etc.; component polarity, component type, value exceeds the allowable range of nominal value, etc.; evaluate the performance of the system composed of the entire SMA component at clock speed, evaluate whether its performance can meet the design goals.