ICT Test

ICT Test

In high volume PCB assembly projects, ICT or in-circuit testing is an essential inspection technology that cannot be overlooked. Its primary purpose is to verify the electrical functionality of the circuit at different stages of the production process, as well as prior to full assembly. This proactive approach enables early detection of faults and defects, ultimately saving production costs and minimizing rework time. 

we hold ICT testing in high regard as a proven technology that has allowed us to consistently provide our clients with high-quality PCB board production. 

Advantages of ICT testing

Excellent Detection Ability: Provides accurate and reliable results for detecting faults such as short circuits, open circuits, and incorrect component connections. Additionally, it can effectively test BGA, which may be challenging to test using other methods.

Fast Turnaround: Although the setup process can be complex, utilizing ICT testing PCB during the project can help to identify and address issues early on, reducing the need for rework and repairs and resulting in faster project turnaround times.

Easy Program Generation: In-circuit test systems can generate most of the necessary programs directly from the layout files, simplifying the program generation process.

Strong Versatility: Test platform supports both Windows and UNIX operating systems, making it versatile and adaptable to a variety of testing environments.

Easy Fault Identification: The system generates results for each node, enabling experts to quickly and easily identify fault points and troubleshoot any issues that may arise during testing.

Disadvantage of ICT testing

Limitations: ICT is primarily utilized for detecting faults at the component level and may not be suitable for detecting faults at the board or system level. Additionally, it may not be effective for testing analog components or high-density PCBA that power cycle.

High Cost: The implementation of testing requires specialized equipment, fixtures, and software, along with regular cleaning and maintenance of test pins, leading to higher upfront costs. As a result, this testing method may not be practical for low-volume projects.

Complicated Setup: The setup process for a system is time-consuming and labor-intensive, involving the development of custom fixtures and test programs that are specific to each board layout.

Operator Training: Skilled operators are required to troubleshoot any issues that may arise during the testing process, making proper operator training critical.

Slower Test Speed: Depending on the complexity of the PCB design and the test method used, in-circuit testing PCB may be slower than other testing processes such as X-ray inspection or AOI inspection.

Types of In-Circuit Testing

Bed of Nails (Bon): It is a conventional method of in-circuit testing that utilizes custom-designed fixtures with spring-loaded pins to make connections with the board during testing. The pins make a connection with specific testing points on the board to enable electrical function testing of the PCB. This technique is well-established and provides high throughput and coverage for high-volume production. However, it requires custom fixtures for every board layout, which can be expensive and time-consuming to design and build.

Flying Probe: It is a more flexible and adaptable ICT technique that uses non-destructive, fixture-less testing. Instead of a fixed bed of pins, a pair of movable probes make contact with test points on the PCB, enabling access to virtually any location on the board. This technique is less expensive for Small batch PCB assembly, as no custom fixtures are required. However, flying probe testing is generally slower than Bed of Nails and can have lower testing coverage.

Each in circuit testing PCB technique has its own features and limitations, and the choice of technique depends on the specific needs of the production process.

ICT Identifiable PCB Defects

Short circuits: Rely on the analysis and identification of test parameters such as resistance, capacitance, and inductance to find short circuit problems between two or more conductive components on the circuit board.

Open circuits: Testing probes apply a test signal to the circuit at a specific point, and if the expected response is not observed, it indicates an open circuit.

Incorrect component values: Predefine the test points and component values before testing, and after the test is completed, we compare the actual values with the expected values to identify any discrepancies.

Component polarity and placement issues: Include polarity testing of capacitors, diodes, and polarity-sensitive inductors to identify specific fault points. Additionally, check for misplaced components, broken or bent pins, and incorrect connections, which may result in lower-than-expected resistance values.

Missing components: Check the test points of the circuit board to ensure that they receive the expected test signal. If a certain test point fails to receive the signal, it may indicate missing components.

Soldering defects: Test for problems such as lack of soldering, virtual soldering, and poor soldering by sending a test signal to the solder joints. If the detection is abnormal, mark the existing problems of the solder joints.