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ICT test method in pcb assembly test
2021-10-02
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Author:Frank

ICT test method in pcb assembly test
PCB assembly is also called PCBA or circuit board, printed circuit board. So when testing pcb assembly, a method called ICT test method will be used in the test process. Today, the editor will come to talk with you.
During the ICT test, the test probe is mainly used to contact the test points on the PCBA board to detect whether there are problems with short circuits, open circuits, and component welding. It can quantitatively measure inductors, resistors, capacitors, crystal oscillators and other devices. It can also perform functional tests on transformers, relays, operational amplifiers, diodes, transistors, optical couplings, power modules, etc., and perform functional tests on small and medium-sized integrated circuits.

 

 Some methods of ICT testing are:

 

1. Analog device test

Use operational amplifiers for testing. The concept of "virtual land" from point "A" is:

∵Ix = Iref

∴Rx = Vs/ V0*Rref

Vs and Rref are the excitation signal source and the calculated resistance of the instrument respectively. Measure V0, then Rx can be calculated. If Rx to be measured is capacitance or inductance, then Vs is an AC signal source, and Rx is in impedance form, and C or L can also be obtained.

 

2. Vector test

For digital IC, Vector (vector) test is used. The vector test is similar to the truth table measurement, in which the input vector is stimulated, the output vector is measured, and the quality of the device is judged through the actual logic function test. Such as: NAND test

For the test of analog IC, the voltage and current can be excited according to the actual function of the IC, and the corresponding output can be measured as a function block test.

 

pcb board

3. Non-vector testing

With the development of modern manufacturing technology and the use of very large-scale integrated circuits, it often takes a lot of time to write vector test programs for devices. For example, the 80386 test program takes a skilled programmer nearly half a year. The large number of applications of SMT devices has made the fault phenomenon of device pin open circuit more prominent. To this end, each company's non-vector testing technology, Teradyne launched MultiScan; GenRad introduced Xpress non-vector testing technology.

 

ICT testing is at the latter part of the production process, and is the first process of pcb assembly testing, so that problems in the production process of pcb assembly boards can be found in time, which helps to improve the process and increase the efficiency of production on the factory floor.

In summary, the above is the relevant content of the ICT test method in the pcb assembly test carefully organized by the editor for everyone. I hope it will be helpful to you. For questions or inquiries, please contact us,