Common methods of PCB inspection

The role of PCB testing is to verify the rationality of PCB design, test the production defects that may occur during the production process of PCB boards, ensure the integrity and availability of products, and improve the yield rate of products.

Common PCB testing methods:

1. Automatic Optical Inspection (AOI)

AOI usually uses the camera on the equipment to automatically scan the circuit board to test the quality of the board. AOl equipment looks high-end, atmospheric, and upscale, but the defects are also obvious. It usually cannot identify defects under bundles.

2. Automatic X-ray Inspection (AXI)

Automatic X-ray Inspection (AXI) is mainly used to detect the inner layer circuits of PCB, and is mainly used for testing high-layer PCB circuit boards.

3. Flying probe test

It uses the probe on the device to test from one point to another on the circuit board when ICT power is required (hence the name "flying probe"). Since no custom fixture is required, it can be used in the test scenarios of PCB quick boards and small and medium batch circuit boards.

4. Aging test

Normally, the PCB is powered on and subjected to extreme aging tests in extremely harsh environments permitted by the design to see if it can meet the design requirements. Aging tests generally take 48 to 168 hours.

5. X-ray detection test

X-ray can detect the connectivity of the circuit, whether the inner and outer layers of the circuit are bulging or scratched. X-ray detection tests include 2-D and 3-D AXI tests. The test efficiency of 3-D AXI is higher.

6. Functional Test (FCT)

Usually simulates the operating environment of the product under test and is completed as the last step before final manufacturing. The relevant test parameters are usually provided by the customer and may depend on the final use of the PCB. A computer is usually connected to the test point to determine whether the PCB product meets its expected capacity

7. Other tests

PCB contamination test: used to detect conductive ions that may exist on the board

Solderability test: used to check the durability of the board surface and the quality of solder joints

Microscopic section analysis: slice the board to analyze the cause of the problem on the board

Peel test: used to analyze the board material peeled off from the board to test the strength of the circuit board

Floating solder test: determine the thermal stress level of the PCB hole during SMT patch soldering

Other test links can be carried out simultaneously with the ICT or flying probe test process to better ensure the quality of the circuit board or improve the efficiency of the test.

We generally comprehensively determine the use of one or several test combinations for PCB testing based on the requirements of PCB design, use environment, purpose and production cost to improve product quality and product reliability.