PCB ICT Testing
Years of Experience
The PCB ICT testing verifies the correct operation and positioning of PCB components. This is done by connecting the board to a machine called in-circuit tester.
During the test, an array of probes scans components for defined electrical properties such as shorts and opens or capacitance and resistance.
An in-circuit test system is basically made up of these main components: the test program, the testing fixture called “bed of nails”, and the tester itself.
- Test Software – this contains instructions for the specified test points on the board. It also defines PCBA parameters to be checked and their “fail and pass” information.
- Test Fixture – the in-circuit test fixture consists of many spring-loaded test pins. These touch the board at the appropriate points during the process, delivering signals to the components and receiving feedback.
- Tester – the in-circuit tester is the machine that perform the entire testing process. While this can be used to check many different types of boards, the software and fixture are PCB-specific.
Comparison of In-Circuit Testing and AOI
In comparison to AOI, in-circuit testing is a more detailed method for checking PCB assemblies. It provides a better analysis of the components, and can detect various after-assembly flaws that would otherwise go unnoticed.
Venture uses both visual and physical tests, such as the in-circuit test procedure, to analyze PCBs during their production process. Here’s a brief comparison of the two testing methods.
In Circuit Testing
A faster method
Comparatively slower method
Typically an after-assembly test
Can be done before and after assembly
How Does Venture Perform In Circuit Testing for Quality Control?
At venture, the ICT test involves a series of steps. Advanced ICT equipment is also used. This ensures the best outcomes when conducting the test, and greater reliability of your assembly printed circuit boards. During the in-circuit testing process, the following takes place.
Step 1: Preparations
PCB in-circuit test starts with making the necessary preparations. A custom testing fixture is made, based on the particular PCBs design specifications. A proprietary testing program is also written.
The fixture contains matrix of testing pins or probes whose positions align with the testing nodes of the PCB. The in-circuit test software, on the other hand, has all the test parameters for the specific board.
Step 2: Loading the PCB
The PCBA to be tested is loaded onto the testing fixture, with the component side facing up. The fixture is a structure that typically contains hundreds of probes whose positions match with those of the PCB points.
For lower production runs, the slower but less costly method called “flying probe” is a more preferred option. This type of test involves moving probes that hover above the PCB, carrying out in-circuit tests at different positions.
Step 3: In Circuit Testing
The actual testing process can now begin. This is done by lowering the board onto the fixture using a vacuum mechanism. It allows the probes to make direct contact with the board’s testing nodes.
The in-circuit tester then takes measurements and compares them to those contained in the design file of the particular PCB. To verify PCBAs, their components are measured for the following:
- Open connections
- Short circuits
- Soldering defects
- Component defects
- Missing components
- Incorrect component position and values
- Power and signal faults
- Capacitance and inductive values
Step 4: Analyzing ICT Results
Results from the test process are analyzed. Faultless PCBs are allowed to move on to the other stages of their production process. The in-circuit test engineer also uses the test results to identify defects and correct them early enough.
Venture makes use of the in-circuit test to check assembled PCB components, ensuring their correct operation and positioning. For more information about our services for PCB manufacturing and testing, feel free to contact us.
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