The ever-evolving technology industry has created a need for more efficient and accurate testing methods. With the increasing demand for electronic devices, such as smartphones, laptops, and other gadgets, the reliability of the devices becomes paramount. One of the crucial steps in ensuring the quality of electronic devices is through testing. There are various testing methods used in the electronics industry, including In-Circuit Testing (ICT) and Flying Probe Testing.
The test is performed on a PCB by injecting test probes into predetermined test points on the board. The probes then measure the electrical performance of the board by checking if the electrical connections between components are functioning correctly. The test can detect problems such as open circuits, short circuits, and component placement errors [1].
On the other hand, Flying Probe Testing is a non-contact testing method that uses small probes to make contact with test points on the PCB. The probes move around the PCB and make contact with each test point, checking the board’s electrical performance.
Both ICT and Flying Probe Testing have their advantages and disadvantages. ICT is ideal for large-volume production because it is fast and can test many boards at once. It is also suitable for testing complex PCBs with high component densities. However, it requires the creation of a custom test fixture for each board, which can be expensive and time-consuming. Flying Probe Testing, on the other hand, is ideal for smaller production volumes because it is flexible and does not require the creation of custom test fixtures. However, it is slower than ICT and may not be as suitable for testing complex PCBs.
Overall, the choice between ICT and Flying Probe Testing depends on the specific needs of the manufacturer. This article will discuss in detail the differences between ICT and Flying Probe Testing, their advantages and disadvantages, and their suitability for different production volumes and PCB complexities.
In-Circuit Testing
Strengths:
- In-circuit testing (ICT) is a powerful and cost-effective tool for quickly identifying defects in printed circuit boards (PCBs);
- It allows for full coverage of the board’s circuitry, which may be necessary if the layout is complex or has multiple layers;
- ICT also allows for non-contact testing, which reduces wear and tear on components during test runs;
Weaknesses:
- ICT requires that all of the components are placed onto the PCB before testing can begin. This can result in longer lead times due to component procurement and handling;
- Additionally, ICT tests become increasingly difficult as board densities increase, since there are fewer available target points to connect probes;
Flying Probe Testing
Strengths:
- Unlike ICT, flying probe testing does not require that components be placed onto the board before testing can begin. This makes it a great option for rapidly prototyping and debugging circuits in the early design stages;
- Flying probe testing also requires fewer target points than ICT, making it better suited to higher-density PCBs;
- Furthermore, flying probes offer superior access to internal layers of complex multi-layer boards, due to their ability to move over these layers quickly and precisely [2];
Weaknesses:
- The accuracy of flying probe tests depends on the operator’s skill level more than with ICT tests since they rely on physical probes making contact with the board rather than a computer-controlled system;
- Flying probe tests are also more expensive and take longer to execute than ICT tests, due to their reliance on manual processes;
- Finally, flying probe tests may not provide full coverage of the circuit boards being tested as there may be areas that are difficult for the probes to access;
How Does a Flying Probe Work?
A flying probe testing system consists of two or more movable test probes that are controlled by a computer program. The probes are mounted on a gantry system that can move them in any direction over the PCB being tested. Each probe has a small diameter tip that can make electrical contact with specific points on the PCB. The computer program controls the movement of the probes and the measurement of electrical signals, based on a pre-defined test plan.
During the FPT process, the probes move over the surface of the PCB, making contact with specific test points. The probes measure the electrical signals at each test point and compare them to the expected values. If the measured values are outside the acceptable range, the system detects a fault and alerts the operator. The operator can then investigate the fault and make any necessary repairs or adjustments.
One of the benefits of FPT is that it can test a wide range of PCBs, regardless of their size or complexity. The probes can reach test points that may be difficult to access with other methods, such as ICT. FPT can also test flexible PCBs and those with irregular shapes, which may not be possible with traditional ICT testing.
Another advantage of FPT is that it is a non-destructive testing method, meaning that the PCB is not damaged during the testing process. This is important for high-value or sensitive PCBs that cannot be replaced easily. FPT also does not require a custom test fixture, which can be costly and time-consuming to design and build. This makes FPT a more flexible and cost-effective solution for low-volume production or prototyping.
How Much Does A Flying Probe Tester Cost?
The cost of a flying probe tester can vary greatly depending on the manufacturer, model, and features of the equipment. Generally speaking, flying probe testers can range in price from tens of thousands of dollars to hundreds of thousands of dollars.
Basic models with limited functionality may start at around $50,000, while more advanced models with higher accuracy and more capabilities can cost upwards of $200,000 or more [3].
Other factors that can impact the cost of a flying probe tester include additional options and features such as automated optical inspection, boundary scan testing, or thermal testing capabilities.
It’s worth noting that there may also be additional costs associated with purchasing a flying probe tester, such as installation, training, and ongoing maintenance and support.
Key Differences Between ICT And Flying Probe Testing
There are several key differences between ICT and FPT that should be considered when choosing a testing method for your needs. These include:
Custom Test Fixture vs. No Fixture
One of the biggest differences between ICT and FPT is the need for a custom test fixture. ICT requires a custom test fixture to hold the PCB in place and provide electrical connections to the test points. This fixture can be time-consuming and expensive to design and build, but once it’s in place, the testing process can be performed quickly and efficiently.
In contrast, FPT does not require a custom test fixture. Instead, the testing is performed using a computer-controlled system of movable test probes that are mounted on a gantry. This makes FPT a more flexible and cost-effective solution for low-volume production runs or when the design of the PCB is still in development.
Accessibility of Test Points
Another key difference between ICT and FPT is the accessibility of the test points on the PCB. ICT requires physical access to the test points, which can be a challenge for complex or densely packed PCBs. This can limit the ability to test all of the necessary points on the PCB, leading to incomplete testing.
In contrast, FPT uses movable test probes that can reach test points that may be difficult to access with other methods. This makes FPT a better solution for complex or densely packed PCBs.
Speed of Testing
The speed of testing is another key difference between ICT and FPT. ICT testing can be performed quickly and efficiently once the custom test fixture is in place. This makes it a good solution for high-volume production runs.
FPT testing can take longer since the probes need to move over the surface of the PCB to make contact with each test point. This makes FPT a better solution for low-volume production runs or when the design of the PCB is still in development [4].
Accuracy of Testing
The accuracy of testing is another important consideration when choosing a testing method. ICT is generally considered to be a more accurate testing method than FPT. Since ICT uses a custom test fixture that provides precise electrical connections to the test points on the PCB, the measurements obtained are typically more accurate and reliable.
FPT relies on the accuracy of the movable test probes and the gantry system. While this system can be calibrated to ensure accuracy, it may not be as precise as the custom test fixture used in ICT.
Cost of Testing
The cost of testing is a key consideration for any production run or prototyping project. ICT can be more expensive due to the need for a custom test fixture. However, once the fixture is in place, the testing process can be performed quickly and efficiently, making it a cost-effective solution for high-volume production runs.
FPT does not require a custom test fixture, which can make it a more cost-effective solution for low-volume production runs or prototyping projects. However, the speed of testing is slower with FPT, which can increase overall costs.
Which Test Is Best For Your PCBA Assembly – ICT Or Flying Probe
Product Design
One of the main considerations when choosing between ICT and FPT is the design of the PCBAs themselves. ICT is typically better suited for complex and dense PCBAs, while FPT is better suited for simpler and less dense designs.
This is because ICT requires a custom test fixture to be created, which can be difficult or impossible to design for complex and densely packed PCBAs. FPT uses a movable gantry with multiple probes that can access all areas of the PCBA, making it a more flexible option for simpler designs.
Coverage
Another key consideration when choosing between ICT and FPT is the level of test coverage required. ICT is typically considered to be a more thorough testing method, as it is able to test a higher percentage of components on the PCBA.
FPT is more limited in its ability to test, as it relies on movable probes that can only access certain areas of the PCBA. This means that FPT may miss certain defects that ICT is able to detect.
Cost
The cost of testing is a major consideration for any PCBA assembly project. ICT requires a custom test fixture to be created, which can add to the initial cost of testing. However, once the fixture is in place, the testing process can be performed quickly and efficiently, making it a cost-effective solution for high-volume production runs.
On the other hand, FPT does not require a custom test fixture, which can make it a more cost-effective solution for low-volume production runs or prototyping projects. However, the speed of testing is slower with FPT, which can increase overall costs [5].
FAQ
1. What is the difference between ICT and FCT?
ICT is performed by injecting test probes into predetermined test points on the board and checking the electrical performance, while FCT is performed by applying different input signals to the board and checking the output signals to ensure that the board is functioning correctly.
2. How is the ICT test performed?
ICT test is performed by injecting test probes into predetermined test points on the board. The probes then measure the electrical performance of the board by checking if the electrical connections between components are functioning correctly. The test can detect problems such as open circuits, short circuits, and component placement errors. ICT requires the creation of a custom test fixture for each board to be tested.
3. Which test is performed by the ICT method?
The ICT method is used to test printed circuit boards (PCBs) for defects. The test is performed by injecting test probes into predetermined test points on the board and checking the electrical performance of the board [6].
4. What are the four types of test probes?
The four types of test probes are:
- Pogo pins: spring-loaded pins that make contact with the board;
- Kelvin probes: used to measure resistance and contact resistance;
- Oscilloscope probes: used to measure signals and waveforms;
- Boundary Scan probes: used for testing digital circuits;
5. What are the 3 main types of ICT?
The three main types of ICT are:
- Analog In-Circuit Testing (AIT);
- Digital In-Circuit Testing (DIT);
- Mixed-Signal In-Circuit Testing (MSIT);
6. What is the difference between MDA and ICT?
MDA is a form of functional testing that tests a PCB for manufacturing defects, such as open circuits, short circuits, and component placement errors. ICT, on the other hand, is a form of structural testing that tests individual components on a PCB.
7. What are the uses of ICT in airports?
ICT is not commonly used in airports, but it can be used for testing electronic components used in airport equipment, such as sensors and control systems.
8. What is the role of ICT in a travel agency?
ICT is not typically used in travel agencies, as it is a testing method used in the electronics industry for testing PCBs [7].
9. What is the purpose of ICT?
The purpose of ICT is to test printed circuit boards (PCBs) for defects, such as open circuits, short circuits, and component placement errors. This helps ensure the quality and reliability of electronic devices.
10. What are the 7 components of ICT
- Test Fixture: a mechanical assembly that holds the PCB being tested and provides electrical connections for the test probes;
- Test Probes: small devices that are placed on the test fixture and make electrical contact with specific points on the PCB being tested;
- Test Software: a program that is used to control the testing process and analyze the results;
- Test Instrument: a device used to measure electrical signals during the testing process, such as a multimeter or oscilloscope;
- Test Point: a specific point on the PCB being tested where a test probe is connected;
- Test Access: the physical space required to connect the test probes to the test points on the PCB being tested;
- Test Coverage: the percentage of the PCB being tested that is covered by the test probes;
11. What are the different types of system testing in ICT
- In-Circuit Test (ICT): a structural test that checks individual components on the PCB;
- Functional Test (FCT): a functional test that checks the overall functionality of the PCB;
- Boundary Scan Test: a test that uses JTAG (Joint Test Action Group) to test the interconnects between components on a PCB;
- Flying Probe Test: a test that uses movable test probes to test specific points on a PCB;
12. What are the advantages of ICT test
- Early detection of defects in the production process;
- Reduction of testing time and cost compared to manual testing;
- High accuracy and repeatability of test results;
- Ability to test a large number of components in a short time;
- Detection of hidden defects that are not visible to the human eye;
13. How long is the ICT test?
The duration of an ICT test depends on the complexity of the PCB being tested and the number of test points. Typically, an ICT test can take anywhere from a few minutes to several hours.
14. Which tube is used for the ICT test?
The tube used for the ICT test is a vacuum tube, also known as a cathode ray tube (CRT). The CRT is used to display the test results on a screen [8].
15. What is a PCB probe?
A PCB probe is a small device used in ICT testing that makes electrical contact with specific points on a printed circuit board (PCB) being tested. The probe is used to measure the electrical performance of the PCB by checking if the electrical connections between components are functioning correctly.
16. What is FPT in PCB?
FPT stands for Flying Probe Test, which is a method of testing electronic circuits and printed circuit boards (PCBs) for defects. The FPT method uses movable test probes to test specific points on a PCB, without the need for a custom test fixture. The FPT method is often used for low-volume production or prototyping, where a custom test fixture is not cost-effective.
Useful Video: ICT Testing VS Flying Probe Testing – PCB Assembly
References
- https://blog.matric.com/ict-testing-vs-flying-probe-testing
- https://www.escatec.com/blog/whats-the-difference-between-in-circuit-test-and-flying-probe
- https://geospacemfg.com/blog/in-circuit-test-vs-flying-probe/
- https://www.vse.com/blog/2019/10/01/understanding-in-circuit-test-vs-flying-probe-for-your-pcba/
- https://www.technotronix.us/pcbblog/in-circuit-test-ict-vs-flying-probe-test-which-one-is-best-for-your-electronic-board-assembly/
- http://smt.iconnect007.com/index.php/article/118301/ict-or-flying-probe-which-test-is-best-for-your-assembly/118304/?skin=smt
- https://hillmancurtis.com/flying-probe-testing/
- https://evertiq.com/nanews/30261