Automated X-Ray Inspection

Automated X-Ray Inspection (AXI) uses X-ray technology to visualize the interior of printed circuit boards (PCBs) and check for hidden defects.

Use

While most inspection methods, including AOI, focus primarily on the surface of the PCB, AXI allows a view through the board and the detection of defects that might otherwise remain hidden, such as improper solder connections under ball grid arrays (BGAs).

Speed and accuracy: AXI is fast, accurate, and can be used on a wide variety of PCBs. Suitability for complex designs: AXI is particularly useful for complex PCBs that would make manual inspection difficult.

Procedure

1. Imaging: An X-ray source and a detector are used to create images of the PCB.
2. Analysis: The software analyzes the images to detect defects such as soldering defects, open circuits, or short circuits.

Advantages & Disadvantages

In-depth inspection AXI can detect defects inside the PCB that are invisible to AOI or the human eye.

Precision With high-resolution X-ray images, AXI can identify even the smallest defects and irregularities hidden in densely populated PCBs.

Reliability Because it relies on X-ray images, AXI is less susceptible to visual illusions or surface reflections that can occur with optical methods.

Cost AXI systems are typically more expensive to purchase and operate than other inspection methods.

Radiation exposure Although radiation doses in AXI systems are minimal, safety precautions and protocols must still be observed.

Complexity Interpreting X-ray images requires specialized software and expertise, especially for complex PCB designs.

2D vs. 3D AXI

2D X-ray Inspection

Function: Provides flat, side-on images of the PCB and its components.
Capabilities: Allows for quick detection of obvious defects like solder bridging, short circuits, or improper solder joints.
Limitations: May struggle to differentiate overlapping components or structures due to its single-perspective view.

3D X-ray Inspection

Function: Uses computed tomography or similar technologies to generate three-dimensional images.
Capabilities: Offers detailed views of components from every angle, making it easier to detect hidden defects.
Advantages: Enables calculation of volume percentage values of solder joints to ensure compliance with specifications.

Differences Between 2D and 3D X-ray Inspection

1. Level of Detail

   • 2D: Provides a flat view.
   • 3D: Allows for spatial representation and deeper component analysis.

2. Time

   • 2D: Faster due to single-perspective imaging.
   • 3D: Slower as it collects more data points.

3. Cost

   • 2D: More affordable and simpler to implement.
   • 3D: More expensive due to added complexity and higher detail levels.