Manual visual testing is to confirm the installation of components on the PCB through human vision and comparison, and this technology is one of the most widely used online testing methods. But as production increases and circuit boards and components shrink, this method becomes less and less applicable. Low upfront cost and no test fixture are its main advantages; At the same time, high long-term costs, discontinuous defect detection, data collection difficulties, no electrical testing and visual limitations are also the main disadvantages of this approach. 

1, Automated Optical Inspection (AOI)
This test method, also known as automatic visual testing, is usually used before and after reflux, and is a relatively new method to confirm manufacturing defects, and has a better check effect on the polarity of components and the presence of components. It is a non-electrical, jig-free on-line technology. Its main advantages are easy to follow diagnosis, easy to develop program and no fixture; The main disadvantage is poor recognition of short circuits and is not an electrical test.

2. Functional Test
Functional testing is the earliest automatic test principle, which is the basic test method for a specific PCB or a specific unit, and can be completed by a variety of test equipment. There are two main types of functional testing: Final Product Test and Hot Mock-up.

3. Flying-Probe Tester
Flying needle test machine, also known as probe test machine, is also a commonly used test method. Thanks to advances in mechanical accuracy, speed and reliability, it has gained general popularity over the past few years. In addition, the current demand for a test system with fast conversion and jig-free capability required for Prototype manufacturing and low-volume manufacturing makes flying needle testing the best choice. The main advantages of the flying needle test machine are that it is the fastest Time To Market tool, automatic test generation, no fixture cost, good diagnosis and easy programming.