PCB ICT Testing

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.

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.