What Is a Function Tester?
A function tester is a device used to verify the functionality of electronic boards, ensuring they operate as intended. It is critical in electronic control systems across various devices, where the first step towards guaranteeing safe and correct operation is to inspect the electronic board for defects.
Inspection methods include AOI (automated optical inspection), ICT (in-circuit testing), and FCT (functional circuit testing), with AOI focusing on visual checks for wiring and component integration defects.
Uses of Function Testers
Function testers assess if an electronic board functions correctly by simulating operational conditions and checking for the correct output signals and component operations. Given the unique functionality required by each board, selecting an appropriate tester is crucial. Applications range from testing power supply boards for correct voltage and current output to evaluating LED lighting efficiency in response to input current.
Principle of Function Testers
Function testers work by supplying power and input signals to the board, and then measuring output signals and component behavior against expected outcomes. This process often involves using test patterns generated by FPGAs to stimulate microcontrollers and ICs on the board. Before testing, a visual inspection is recommended to identify any potential defects that could lead to board damage during testing.
Unlike ICT, which focuses on the electrical characteristics of individual components, function testing evaluates the board’s overall operational capability.
Other Information on Function Testers
1. Difference From In-Circuit Testing
In-circuit testing primarily checks for correct component placement and soldering, not evaluating functional performance or internal connections like BGAs. Function testers, however, are designed to identify functional failures, with many models incorporating ICT capabilities for comprehensive evaluation.
2. Examples of Actual Function Test Items
Functional tests may include assessments of current and voltage in output circuits, LED operation, microcontroller functionality via FPGA-generated patterns, and connector integrity. With the increasing complexity of electronic circuitry in devices like smartphones and automotive controls, custom testing solutions, including peripheral circuits and electromagnetic shielding, are often required.