What techniques are used for X-ray inspection of assembly drawing pcb?

X-ray inspection of assembly drawing pcb

X-ray inspection of an assembly drawing pcb is used to check the internal structure of a product without breaking it open or disturbing the contents. X-rays are transmitted through the object to produce shadow images that are then scanned and recorded for processing. The resulting images are analyzed using image processing software to detect the size and shape of expected features and to identify any unexpected features. This process is much faster than traditional optical inspection and requires no physical contact with the product.

A typical PCB assembly drawing includes a schematic depicting the circuit board components and their connections. Each component is typically represented by a symbol, which can be a shape or letter that indicates the type of device, such as a triangle for a diode or rectangle for a capacitor. The traces that connect the components are also shown on the drawing, as well as any labels indicating specific instructions, such as “omit” or “install in a certain orientation”. The CAD drawings must be clearly labeled and organized so that the assembly technicians can understand them during the assembly process.

The assembly drawing pcb must contain a Bill of Materials that clearly lists all the components required for the project, including their shapes and reference designators (alphanumeric labels assigned to each component). It should also include dimensions that show how large or small a component is and its position on the board. In addition, the assembly notes must contain information about any special requirements for the production of the board such as polarization or stagger marks and silkscreen instructions. The CAD drawing should also have a side view of the board for cases when mechanical parts need to be attached.

What techniques are used for X-ray inspection of assembly drawing pcb?

X-rays can help catch problems that are impossible to see with the naked eye, such as opens, shorts, misalignment and broken traces. The X-ray technique works by detecting differences in the density of different elements in the material being inspected. For example, a solder joint made of heavy copper elements appears darker on X-ray images than a solder joint that is formed with lighter, thinner copper elements. This is one of the reasons why X-rays are particularly effective at inspecting BGA chip solder joints, as well as QFN/DFN and press-fit connectors.

Furthermore, assembly drawing PCBs facilitate the manufacturing process, especially when production is scaled up. In the mass production of smart home devices, consistency is key. Assembly drawings guide automated machines and human workers alike, ensuring that each PCB is manufactured to the same standard. This consistency helps in maintaining quality control and reducing the likelihood of defects, which can be costly both in terms of repairs and customer satisfaction.

A typical X-ray inspection system consists of an X-ray tube that produces the X-rays, a collimator that shapes the beam to fit the object under test and a detector that converts the X-rays into an electrical signal that is recorded on a monitor or radiograph film. The system is usually enclosed in lead shielding to protect the operators from radiation exposure. Hardened computers running image reconstruction and defect recognition algorithms control the hardware and record the X-rays for analysis. X-rays can be interpreted by computer to generate 2D and 3D models of the internal structures of the assembled PCB, which are then displayed on a high resolution monitor for operator inspection. X-rays can also be used to inspect the quality of solder joints and other defects that are not detectable by optical inspection techniques.

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