As the current SMT technology continues to mature, the components in the PCBA assembly process have become smaller and smaller, making the PCBA more powerful. At the same time, it also brings huge challenges to testing and inspection. Testing is a crucial step to ensure that high-quality PCBA products are delivered to customers. Inspection and testing can reduce processing risks. The following is a collection of several test methods in the PCBA processing industry.
1, manual visual inspection
Visual inspection can be achieved in every step of the PCBA process. PCBA assembly manual visual inspection is the most primitive method in PCBA quality inspection. It only uses eyes and a magnifying glass to check the welding conditions of the circuit and electronic components of the PCBA board, such as the welding method, whether the solder joints are bridged, whether there is less soldering or welding failure Completeness. In the visual inspection, the magnifying glass is the basic tool, and the metal needle can be used to check the welding incompleteness on the IC lead.
2, online tester (ICT)
On-line tester is widely used in PCBA processing industry because of its excellent testing and inspection performance. ICT can almost find soldering and component problems in PCBA. It has high speed and high stability. Among them, the electrical probe test fills the printed circuit board (PCB) to check short circuits, open circuits, resistance, capacitance and other basic quantities to show whether the components are properly manufactured.
3, automatic optical inspection (AOI)
Automatic optical inspection is a non-contact testing method. Automatic optical inspection plays an important role in inspection. Automatic optical inspection is an automatic visual inspection in the manufacturing process of printed circuit boards, in which the camera automatically scans for catastrophic failures (such as missing parts) and quality defects (such as rounded corner size or shape or component skew) of the tested PCBA board.
4, automatic optical inspection (AXI)
For the widespread use of BGA and CSP, typical inspection methods like ICT cannot inspect the solder joints embedded in the component. AXI can test for misalignment, lack of balls and solder deposits. AXI uses X-rays to penetrate solid objects to capture their photos. It can be divided into two types: 2D and 3D.
5. Functional circuit test
Functional circuit test is the last test before PCBA products go on the market. Unlike other tests (such as AOI, AXI, and ICT), FCT is designed to make UUT (unit under test) work in a simulated environment and use output data to check its actual performance.
6. Sample inspection
Before mass production and assembly, PCB manufacturers and assemblers usually conduct a first sample inspection to check whether the SMT equipment has been properly prepared, so that vacuum nozzles or alignment problems can be avoided in mass production, which can cause problems in PCBA board production. This is called the first inspection.
7, flying probe tester
The flying probe probe is suitable for the inspection of high-complexity PCBs that require expensive inspection costs. The design and inspection of the flying probe can be completed in one day, and the assembly cost is relatively low. It can check the open circuit, short circuit and direction of the components mounted on the PCB. In addition, it works well in identifying component layout and alignment.
8. Manufacturing Defect Analyzer (MDA)
The purpose of MDA is only to visually test the board to reveal manufacturing defects. Since most manufacturing defects are simple connection problems, MDA is limited to measuring continuity. Usually, the tester will be able to detect the presence of resistors, capacitors and transistors. You can also use protective diodes to detect integrated circuits to indicate whether the components are properly placed.
