- Visual Inspection:
The first step in testing the PCB is a visual inspection. With the help of a magnifier, the technician looks for any visible defect. These defects may include missing components, misplaced components, or soldering defects. It is cheap but a time-consuming procedure and has a high chance of human error. It can only be utilized to inspect large boards.
- In-circuit testing:
After the PCB assembly, the manufacturer runs an in-circuit test. It is specific for each board type. Any critical error in the resistors, capacitors, transistors, and any shorts or opens, is found using it. It has higher fault coverage and is performed within a few minutes. Automated with software, ICT can test boards in large quantities. In-circuit testing is costly because it requires a unique fixture for a different board. This test has a high maintenance cost. The fixtures are connected to each pin individually, so it becomes difficult to test small-sized PCBs.
- Flying Probe Test:
The PCBs which cannot be tested using ICT, FPT is used to examine them. Comparatively, with in-circuit testing, the flying probe test does not require fixtures, making it cost-effective. It detects faults in small boards with a high component density. Mass testing becomes difficult using FPT as it is a time-consuming procedure, which takes approximately 20 minutes to test each board.
- Boundary Scan Testing Method:
After the PCB assembly, the Boundary Scan Testing method checks the interconnections on the printed circuit board. It is done without using any physical test probes. There is no physical damage to the board while testing the device by using this method. It is a low-cost and time-saving test. To make the device undergo Boundary Scan, additional silicon boundary and more pins and power consumption requirement affects the board’s performance.
- Burn-In Testing:
The burn-in testing method ensures that the board can survive excessive loads. It checks the board’s performance before it is delivered to be used in the field. The board’s operation with the temperature changes and fluctuating voltages is examined, confirming that the product is steadfast. Though it is a time-demanding procedure, it helps the manufacturers to make reliable boards used in equipment with no room for error, such as medical equipment.
- Functional Testing:
Functional testing examines the PCB as a whole and not specific components. It determines the behavior of the PCB. The lifespan of the PCB is checked using this method so that it will not fail immediately after leaving the factory. It includes several tests under it. Like, X-ray inspection creates 2D and 3D images of the board, giving a detailed view of the board.
Another procedure, micro-sectioning analysis, gives a 2D image of the board to identify defective components. PCB solder-ability test helps reduce any fault in assembly and increases the product reliability. Operational product manufacturing is ascertained using PCB functional tests. The test is customizable as per the type of PCB, which makes it convenient.
Conclusion:
The assembly of the PCB is a complicated procedure, yet the work does not end here. After the PCB board assembly, each board undergoes a series of tests for quality assurance. Every testing method comes with its pros and cons. Hence the manufacturer must use the most reliable test through which he can check the product’s function and reliability.