In-circuit testing (ICT) and flying probe testing (FPT) offer similar coverage in their tests, discovering most manufacturing defects that often occur in printed circuit boards (PCBs). These include:

Component orientation

The two, however, differ on their:

Test time periods
Per-unit costs
Custom tooling
Non-recurring engineering charges
Digital logic testing


ICT is a powerful tool for PCB testinprinted circuit boardsg. It uses bed of nails in-circuit test gear to access the circuit nodes of a board and check the performance of each component. It can also test some functionality of digital circuits, although the complexity involved can make it economically prohibitive.

ICT is most suitable for testing products that are more developed and high-volume. However, the up-front costs and development lead time with ICT are higher and longer, respectively, than those of flying probe testing (FPT). This is because your manufacturer must explicitly create a custom ICT fixture for each PCB.

The good thing with ICT is that after the tool is developed, costs per unit tend to be lower than with FPT because it only takes about 1 minute for one test cycle. With FPT, it can take up to 15 minutes per board.


Quick tests per PCB unit
Lower costs per unit than FPT
Checks for shorts, opens, resistance, capacitance, and component tolerance
Tests components individually
Tests for logic functionality
Capable of performing on board verification FPGAs
Can be set to turn on and test LED components – say by enabling verification of color and brightness
Ability to check the integrity of BTC components’ soldering using a pressure test


Long development lead time
High up-front costs
Programming and custom tooling are required
Doesn’t test connectors or non-electrical components
Doesn’t test components working together


Unlike an ICT machine, an FPT does not utilize a bed of nails fixture. Instead, it uses a small number of movable and fixed probes to easily make a simultaneous in-circuit test of the top and bottom of your PCB. It’s made up of high-precision needles — some machines use as few as four needles, while others can use as many as 20 per PCB side. They’re programmed to contact component pins and perform electrical and functional tests to determine if the board is fit for the field.

FPT is most suitable for products that are in the early stages of development and are low-volume orders. It requires no custom tooling, and customization for each PCB is carried out through programming using the CAD data you provide to the manufacturer. With FPT, costs-per-unit are higher compared to ICT because of longer test cycle time periods per board (up to 15 minutes).


No custom tooling needed
Programming requires less time
Checks for shorts, opens, resistance, capacitance, and component tolerance
Tests components individually
Low up-front costs
Ability to test LEDs
Capable of performing on board verification FPGAs


Higher cycle test period times and cost-per-unit costs
Doesn’t test connectors or non-active components
Doesn’t test components operating together