PCB Technical - Understand the concept of PCBA circuit board ICT tester

In the process of PCBA board processing, how to find poor quality in the production process early and analyze and solve it early can reduce losses and increase profits for the electronics manufacturing industry. Therefore, the testing of PCB products has become an indispensable part of the PCB electronics manufacturing process. As a result, ICT technology has flourished.

1. What is ICT

ICT is the abbreviation of In Circuit Test. The Chinese name is online tester (or ATE Auto Test Equipment). It is a PCB automatic tester, also known as PCB static tester (because it only inputs a small voltage or current to Test, will not damage the circuit board), online test is a test technology that does not disconnect the circuit and does not remove the PCB components. The main function is to test the short circuit and open circuit of the circuit board and various electronic parts such as PCB resistance, capacitance, Whether diodes, transistors, transistors, ICs and other parts are wrong, missing, defective, or poorly assembled, and clearly indicate the specific location of the defect to help users ensure the quality of the product and improve the efficiency of defective product inspection and repair.

2. Types of ICT

ICT generally has offline (Off-Line) and online (In-Line) depending on the type of production. Generally, ICT needs to customize test fixtures according to the size of the PCBA board and the location of electronic components, and in order to meet the production of PCBA samples The short delivery time, a small amount of flexible production capacity, and a flying probe tester (the advantage is that there is no test fixture), the test needle can be programmed to move the position, but due to the test time and the slow speed of the new program, it is usually used For the production test of PCBA samples, the direct use of ICT for mass products can maximize production capacity.

3. ICT functions and capabilities

ICT is like a powerful multimeter, which can effectively isolate the electronic components on the PCBA board, but the multimeter cannot.

ICT is a static test (not energized), which can test and judge the specifications, short circuits, and open circuits of common electronic components such as resistors, capacitors, inductors, diodes, triodes, and other common electronic components. In addition, it can also be tested The process of programming the IC data.

4. Where is ICT used

ICT is used at the back end of the SMT process, usually behind the SMT line (after the Reflow process). After the ICT test, the SMT process is screened out and the SMT production yield rate is abnormal.

Since ICT needs to test electronic components at different positions on the PCBA board, ICT test fixtures must be made to match different products. The test fixtures have vacuum and pneumatic types due to different ICT brands and models. Generally, probes of different specifications (size, shape, diameter) are used to contact the circuit board or electronic components. Therefore, when the density of electronic components on the PCBA board is too high and there is no space for needle placement, ICT may not be used, so ICT still has The conditions of use are restricted.

5. Stress test of ICT test fixture

Due to the difference in the number of PCB components and PCB distribution positions of electronic products, the number and density of probes for ICT test fixtures vary. When the probes touch the circuit board for testing, the circuit board may exceed the allowable range. The pressure (stress) of the circuit board will cause the deformation of the circuit board, which may cause the hidden danger of damage to the PCBA board. Therefore, it is usually necessary to perform a stress strain test before importing the ICT test fixture to reduce the strain value to the allowable safe range.