In-circuit Test vs. Flying Probe: A Comparison
The in-circuit test and the flying probe are two different methods for testing printed circuit boards. Continue reading to understand the difference between the in-circuit test vs. the flying probe two, so you can decide which one is best for your PCB assembly.
What is an In-circuit test (ICT)?
In-circuit test (ICT) access circuit nodes using a bed of nails fixture. These nodes are tested for continuity and electrical characteristics such as signal strength, voltage levels, or resistance.
ICT is used in the manufacturing environment where boards must be thoroughly inspected before leaving the production floor. This ensures that no assembly errors were made during the soldering process – either on the board or when installing components.
This testing method is often suitable for testing high-volume and more developed printed circuit boards.
Pros of In-circuit Test
- Offers a quick test per PCB unit
- Can perform on-board verification FPGAs
- Can test logic functionality
- Offers verification of FPGA
- Tests components individually
- Checks for resistance, capacitance, shorts, as well as component tolerance
- Lower testing costs per unit
Cons:
- The development lead time is longer
- High up-front costs
- Requires custom tooling and programming per printed circuit board
- Does not test non-electrical components and connectors
What is the Flying Probe Test?
The flying probe test (FPT) is a method used to test PCBs and electronic devices. It uses spring-loaded probes that are dragged across the surface of the PCB’s pads and traces, using gravity as its mechanism for applying pressure on these components during testing.
There is no need for dedicated equipment or fixtures – flying probe testers can be integrated into an existing production line.
FPT tests any electrical components on a PCB, from power inputs and outputs to ICs. It also verifies the functionality of connectors by checking for shorts, opens, bad contacts, or misalignment between them. In addition, it can be used to check for solder bridging in pads and verify that there are no dry solder joints.
FPT is often performed after components are soldered to the PCB to be tested wholly assembled before being moved for shipping or storage, thus reducing time and effort in post-production testing.
How Does a Flying Probe Work?
As mentioned above, unlike in ICT, FPT doesn’t require a bed of nails fixture. A flying probe uses fixed but movable probes that are attached to the test machine. The system consists of a handheld probe and a ground lead.
The signal generator is used to generate signals sent through the PCB via flying probes attached to the tip of the handheld probe. A measuring device measures values from different parts on board to check for the proper functionality of components, power distribution, and other values.
How much does a flying probe tester cost?
The costs of FPT vary depending on the manufacturer and the model of the probe tester. Contact us for a quote and pricing information.
Advantages of Flying Probe Test
- No need for fixtures
- Lower upfront costs
- Less custom tooling required
- Offers on-board verification of FPGAs
- Higher testing throughput per machine
- Verifies the functionality of all electrical components on-board, including power input and output pins
- Extremely flexible and can be used on all types of printed circuit boards
Disadvantages of Flying Probe Test
- A bit slower than ICT
- Does not text non-active components and connectors
- Not suitable for high-volume products
In-circuit Test vs. Flying Probe: Which One Is Better?
While both testing methods are widely used and provide a range of benefits, you might want to choose FPT because it has lower initial costs, higher testing throughput per machine, and is extremely flexible.
Our FPT machine can perform a powered-on test along with boundary scans like an ICT machine. It can test for the functionality of all electrical components onboard, including power input and output pins.
With FPT, you do not need custom tools and programs to test your PCBs. This significantly lowers the costs associated with testing. Flying probe testing is also a great complement to in-circuit testing because it can be used before, after, and even during soldering.
Choose Geospace Technologies
At Geospace Technologies, we can provide all the services you need, from flying probe testing to in-circuit testing. Our engineers are established to know how to design your products to meet the rigorous standards you demand.
With a goal to provide customers with the best products and services available in the industry, Geospace improves quality by finding defects before they become a problem for you or your customers. Contact us today to learn more about our PCB Assembly services.