To manufacture electronics correctly, it is important to use the right PCB inspection method. This type of inspection detects any faults that exist, shortly after a product has been manufactured. Checking for faults is just as important in low volume / small scale manufacturing, as it is in high volume / large scale manufacturing, particularly with the complex designs of many modern PCBs.
When it comes to PCB inspection, there are a number of different methods to choose from. The right method to use will depend on the type of PCB, how far the manufacturing process has progressed, and the defects that you wish to test for. Producing a sound testing and inspection plan is vital to ensure a product of high quality.
The most popular form of PCB inspection is automated or automatic optical inspection. Here, an optical system is used, which takes a photo of the assembled product, then compares this with a photo of a correct assembly to find any defects or other problems. This type of inspection is used by businesses of all types. As such, it has been refined to operate in a reliable way.
Manual inspections involve people visually examining the boards/assemblies to detect any issues. This method has proven to be expensive and ineffective, compared to automated methods. Prior to automation though, inspections had to be carried out like this. For simple units, this type of inspection can suffice.
ALT (Automatic Laser Test) measurement is another printed circuit board inspection method. This can be used to gauge solder joint dimensions, along with the reflectivity of different parts. As surface mount technology has advanced, PCBs have gained in complexity. This poses obstacles for manual and automated inspections.
To deal with these obstacles, xray inspection equipment can be used. This type of inspection is perfect for complex PCBs, and provides benefits that other methods don’t – like being able to look through chip packages. Also, it is effective at examining printed circuit boards that are densely packed, and it enables solder joints to be more closely inspected.
Nowadays, with large scale production, the majority of manufacturers use automated systems to inspect printed circuit boards. In addition, there are certain key parts of the examination process that require hybrid inspection methods. Sometimes, for instance, you would test a solder joint using both manual inspection and automated inspection. Moreover, xrays can be an excellent option for some electronic assemblies, with ‘concealed’ solder joints that need checking.