SMT BGA Solder Joint Quality Inspection Technology (Part 2)

2025-05-05

X - ray Image Acquisition

1. Film - based X - ray Inspection

Film - based X - ray inspection systems utilize industrial X - ray cabinets and X - ray film cassettes to record X - ray images on film. Then, the images are viewed through a film video player for detailed inspection at high magnifICation. This process is time - consuming, but it can present more subtle and color - accurate X - ray images.

2. Real - time X - ray Systems

Real - time X - ray inspection systems use an X - ray source and a detector system that converts the invisible X - ray image into a video signal. These systems can provide immediate imaging results of the sample. The images formed by these systems should not be distorted or contain artifacts caused by the X - ray system itself. Figure 3 shows the desired image quality level of a manual X - ray inspection system. Figure 4 shows examples of pincushion distortion and voltage overexposure. Available real - time systems vary widely in size, from small desktop systems to large floor - standing control systems. The available voltage range of X - ray sources is also quite broad. There is no specific voltage regulation for BGA inspection.

Figure 3: Image Quality of Manual X - ray Inspection System

Figure 4: Examples of Pincushion Distortion and Voltage Overexposure

The required voltage depends in part on the sensitivity of the specific X - ray system used and the structure and properties of the BGA being tested. For example, a BGA with a copper heat sink requires a higher penetration voltage than a PBGA or CBGA. However, a BGA with an aluminum heat sink does not require a high voltage because aluminum is a low - density material and allows X - rays to penetrate more easily compared to copper.