X-RAY Inspection: PCB/PCBA Project Quality Guardian

As a vital component in electronic applications, the process of manufacturing PCBA boards is highly intricate. Any error in design, manufacturing, or assembly can severely impact the performance of electronic applications. Beyond commonly used applications such as mobile phones and computers, PCBA is also utilized in sophisticated fields like military and aerospace. In these high-end applications, PCB boards are increasingly smaller in size, while the density of internal structural components is progressively more complex. Consequently, it can be challenging to detect failure issues. To overcome these difficulties, X-RAY inspection has become an indispensable inspection method in the PCB manufacturing and assembly process. At FS Technology, we specialize in offering detailed information on this highly effective PCB testing method.

What is PCB X-RAY inspection


X-RAY detection is a non-destructive testing method that can be utilized for both PCB and PCBA. In the manufacturing process, it can assess the quality of the inner layer board, while in the assembly process, it can detect issues like solder joint quality and component placement. The principle of this detection method is to utilize high-energy electromagnetic radiation to pass through the material and generate an image of its internal structure, thus revealing internal problems that cannot be seen by the naked eye.

In high-density PCBA projects, even skilled technicians and advanced AOI equipment may fail to identify issues. However, X-RAY inspection can easily detect problems in complex PCB designs and components. X-ray machines used during inspection can provide a magnified view of a circuit board or component, allowing technicians to examine even the smallest details. This technology is a critical tool in ensuring the quality and reliability of PCBs for a wide range of applications, including consumer electronics, aerospace, and defense.


  • Non-destructive testing: It is a valuable process for sensitive components that are difficult to replace since the entire testing process does not have to physically touch the board, preventing damage to the PCB or any other components on the board.
  • High-quality imaging: X-ray test generates high-quality images of the internal structure of the circuit board during inspection, facilitating the detection of faults that are difficult to identify through other testing methods.
  • Fast and accurate: The efficient and rapid processing of this technology is extremely advantageous for quick turnaround PCB assembly projects, ensuring that manufacturing processes are not slowed down by lengthy inspection procedures.
  • Cost considerations: X-ray inspection incurs additional costs compared to free testing methods such as visual inspection and AOI inspection.
  • Technical expertise: The inspection process necessitates the involvement of experts and technicians who can accurately capture X-ray images and interpret the results.
  • Radiation exposure: During X-ray inspection of PCBs, workers may be exposed to ionizing radiation that can be harmful if not properly controlled. As such, it is essential to implement appropriate safety measures to minimize the risk of radiation exposure.

How to ensure the quality of X-Ray detection

Advanced X-Ray equipment

  • AXI Machines: Are designed for high volume PCB assembly projects, where a high degree of automation is required to scan and inspect multiple boards quickly and accurately.
  • Manual X-ray Machines: These machines are often used for low-volume or prototype projects due to the need for manual positioning of the PCB for imaging. They are also suitable for inspecting larger or irregularly shaped components.
  • Micro-focus X-ray Machines: Have a small focal spot size and are used for high-resolution imaging of small components and structures on PCBA boards. They are ideal for high-precision applications that require detailed imaging of tiny features.
  • Computed Tomography (CT) X-ray Machines: Use CT scanning technology to generate 3D images of PCBs for more detailed analysis. They are used for complex PCB assemblies that require detailed inspection of internal structures and hidden features.
  • In-line X-ray Machines: This machine is integrated into the production line and scan PCBs synchronously during the production process. They are suitable for high-volume production environments where real-time inspection is required.
  • Off-line X-ray Machines: These machines are used for postpartum secondary detection or sampling detection. They are ideal for inspecting finished products or testing a small sample of PCBs from a large production run.
  • Cabinet X-ray Systems: These systems are designed for the inspection of small and medium-sized PCB boards. They are equipped with a small X-ray tube and flat panel for generating circuit images. They are often used for quick and easy inspection of small components.
  • Floor Standing X-ray Systems: These systems are designed for the inspection of large PCB panels. They are larger in size than cabinet X-ray systems and feature a high-power X-ray tube and larger detectors. 

PCB X-Ray inspection process

  1. PCBA Board Cleaning: Prior to scanning, it is imperative to clean any dirt or impurities on the board surface to prevent interference with the X-ray produced images.
  2. X-ray Inspection: Place the circuit board in the X-ray machine, turn on the switch, and high-energy electromagnetic radiation will penetrate the board’s interior to capture images of the internal circuit structure.
  3. Image Analysis: Utilize companion software to analyze the captured images and detect and measure any faults.
  4. Reporting: In the final stage, any defects identified during the X-ray inspection process are documented in a report. This report is utilized to troubleshoot and repair the board to ensure proper functionality.

X-Ray Inspection Best Practices

  • Equipment Calibration and Maintenance: It is crucial to have a professional technician calibrate and properly maintain the equipment before conducting circuit checks.
  • Accurate Inspection Settings: Utilize precise inspection settings tailored to the size and structural complexity of the PCB board.
  • Technician Training: Ensure that technicians conducting the inspections receive proper training to develop the ability to analyze X-ray images and identify defects.
  • Regular Validation of Inspection Process: Regularly validate the inspection process to ensure its accuracy and validity.

Advances in X-ray Inspection Systems

As X-ray inspection technology continues to evolve, PCBA companies can provide more reliable and accurate circuit board inspection services through advancements in both hardware and software, such as the X-ray source and detector.

  • Advances in X-ray Sources: Equipment manufacturers have made microfocus X-ray sources mainstream in electronics manufacturing, which produce high-resolution images of PCBs and speed up inspections.
  • Advances in Detectors: The use of flat-panel detectors by major PCBA companies enhances the practicality of X-ray technology in PCB projects. Additionally, the development of photon counting detectors has improved the sensitivity of X-ray detection, enabling engineers to better focus the rays.
  • Advances in Inspection Software: FS Technology uses a 3D imaging system to inspect the entire board at 360° without dead angles. With this technology, we can rotate and zoom in on specific areas of the board. The use of ADR, or automatic defect recognition software, can save time and prevent manual detection errors.
  • Artificial Intelligence: The application of AI technology in PCB inspection can not only detect current board errors, but also predict the possibility of defects based on design and other factors. AI algorithms are a new development in X-ray systems.


X-ray inspection is a highly valuable technique for the electronics industry, providing an accurate and reliable process for inspecting circuit boards. As a non-destructive testing technique, it is suitable for both prototypes and mass production, reducing the risk of product damage or recalls.

Looking to the future, research and development efforts are focused on enhancing the speed, accuracy, and efficiency of the inspection process.

One promising area of development is the significance of machine learning, which can improve X-ray inspection accuracy and defect discovery efficiency.

Another area of development is the creation of new X-ray detectors capable of making higher-resolution images, enabling even more detailed inspections.

Additionally, integrating X-ray inspection into automated manufacturing processes can streamline the inspection process and improve efficiency.

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