What is ICT test for PCBA test
ICT test is a common PCBA test method in PCBA processing. Shenzhen Grace Electronics is a professional one-stop fast production service provider of PCBA, SMT patch, circuit board proofing, and PCB design. It is familiar with various PCBA test methods and is committed to Provide high-quality EMS electronics manufacturing services to customers worldwide.
The ICT test of the PCBA test is mainly through the test probe contacting the test points on the PCBA board, which can detect faults such as short circuit, open circuit, and component welding. Capable of quantitative measurement of resistance, capacitance, inductance, crystal and other devices, functional testing of diodes, triodes, optical amplifiers, transformers, relays, operational amplifiers, power modules, etc., and functional testing of small and medium-sized integrated circuits, such as all 74 series, memory class, common driver class, exchange class IC.
PCBA test common ICT test methods
1.Analog device test
Test with operational amplifier. The concept of "virtual ground" from point "A" is:
∵Ix = Iref
∴Rx = Vs / V0 * Rref
Vs and Rref are the excitation signal source and the instrument's calculated resistance, respectively. Measure V0, then Rx can be found. If the Rx to be measured is a capacitor or an inductor, the Vs AC signal source and Rx are in the form of impedance, and C or L can also be obtained.
2. Vector test
For digital IC, use Vector test. The vector test is similar to the truth table measurement, stimulating the input vector, measuring the output vector, and judging the quality of the device through the actual logic function test. Example: NAND gate test
For the test of analog IC, the voltage and current can be stimulated according to the actual function of the IC, and the corresponding output can be measured as a function block test.
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 a vector test program for the device. For example, the test program of the 80386 requires a skilled programmer for nearly half a year. The large number of applications of SMT devices has made the open-circuit fault phenomenon more prominent. To this end, the non-vector test technology of various companies, Teradyne launched MultiScan; Xpress non-vector test technology launched by GenRad.
ICT testing is at the back end of the PCBA production process. The first process of PCBA testing can timely find problems in the PCBA board production process, which helps to improve the process and increase the efficiency of production.