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PCB X-ray Inspection

Most quality products that are available in the market today are because of quality inspection. The quality inspection eliminates the unnecessary cost, time wastages, and failures. It also improves an organization’s reputation and client’s trust. Hence, partnering with a reliable PCB manufacturer with High-quality standards of X-ray inspection is vital. This is what UNI X-RAY offers.

An understanding of quality control with excellence is at the core of our services at UNI X-RAY. We have full-service solutions for inspection and testing with our X-ray inspection station with image identifiers, an x-ray source comprising digital controls, and an X-Y table for fine-tuning. UNI X-RAY cuts across various industries to make available industry-standard PCB inspection at your demand.

UNI X-Ray delivers inspection as a standard service with PCB manufacturing and a reputation for providing consistent quality. UNI X-RAY can supply all your PCB manufacturing needs.

Defects detection type

  1. shorts caused by solder bridging between the balls,
  2. tilted BGAs, 
  3. BGA voiding, 
  4. insufficient/excess solder, 
  5. BGA missing balls,
  6. BGA poor wetting 
  7. BGA misalignments.

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Why Global Clients Choose Us?

18 Years of Expertise

We have over 18 years of experience that specializes in X-ray Technology.

Excellent Image Quality

Uni X-ray produces X-ray machines that offer excellent and ultra-sharp image qualities.

High Degree of Safety

Our X-ray machine is one of the safest choices you can make because it ensures maximum safety.

Extremely User-friendly

Uni X-ray produces machines that have an easy mode of operation.

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PCB X-ray Inspection

  1. Principles of X-ray Inspection

If you know anything about X-rays, you will know that it has a considerable advantage over other inspection forms like Automatic Optical Inspection (AOI) and other visual inspections. This advantage is reliant on the absorption abilities of materials.

Material absorption of X-rays is based on the density, thickness, and the atomic number of the material. The heavier a material, the more X-ray it will absorb and vice versa.

To carry out any inspection using an X-ray device, one will rely on its projection microscope, which begins with X-rays in the X-ray tube. The radiation produced is then passed through the PCB to be inspected.

Based on its density and thickness, the material then absorbs the projected X-rays and reflects an image on a detector. The image detector reveals the material’s shadow, with the shadow becoming deeper with a higher material density.

 Hence, to adequately detect faults in the PCB, the images produced by the X-ray must be clear and distinct to allow for a comprehensive assessment and analysis. The X-ray device’s magnification level is critical to achieving the inspection objectives both in the short and long term.

Another essential feature of the X-ray device is its ability to assess CSPs and BGAs from oblique angles. This enables a more critical and detailed inspection of solders to miss no soldering error during the inspection. Also, it allows for adequate analysis of the thickness and size of the soldering.  


  1. Why do we need a PCB X-ray inspection?

There are different soldering techniques with varying types of packages. For leadless packages like BGA assemblies and QFN designs, the PCBs are connected to the components below the component’s body.

This makes PCBs a bit tedious and will require much more than the usual visual and optic inspections. For a quality inspection that meets high-quality assessment standards, you will need to employ an X-ray inspection for accuracy and thoroughness.

There has been a recent popularity in using array packages like the QFN, CSP, BGA, and flip-chip in most industries, including aerospace, communication, industrial control, and the military. The soldering joints in these packages are now found below the packages.

This new package technology makes it difficult to carry out accurate PCB inspection using the age-long inspection methods. Also, the higher densities of PCBs, the hidden soldering, and their buried holes has made the usual method of assessments like ultrasonic, optical, and thermal image grossly inadequate. All these are the implication of small leads and packages caused by the Surface Mount Technologies.

There is a need to consider X-ray systems for inspection all in a bit to follow the trend of nanotechnologies and miniature semiconductor components manufacturing. X-ray inspection methods give better assurances when it comes to inspecting hidden solder joints and connections.


  1. How does an X-ray machine find PCB defects?

A PCB goes through the three planes of X, Y, Z, using a four-axis manipulator which also tilts the PCB to various angles. Using a joystick, an operator can manually control the manipulator during an inspection.

It is also easy to control the manipulator using written programs to carry out specific movements during the inspection of individual components.

The magnification changes as the PCB distance is controlled by the Z motion controls relative to the source producing the X-ray. The minimum distance between the PCB sample and the source must be 20mm if the algorithm must detect flaws accurately for the experimental setup.

This setup enhances magnification significantly but reduces the number of components that can be viewed at one time. Tilting the BGA to different angles for better assessment and generating a wholesome image is again achieved using the manipulator.

Using the manipulator to control the BGA positioning and angles enables an accurate assessment of its defects. Nonetheless, choosing an optimum angle that allows for suitable magnification is essential. The distance continuously increases between the X-ray source and the PCB as the tilting continues. This might lead to a collision of the sample and the conveyor or source if not checked.


  1. What defects can an X-ray machine detect on PCB?

X-rays and image processing programs allow for detecting and analyzing defects found in IC packages, but an image needs to generate first. This image is produced by the projection of X-rays on the IC package and a reflection of the soldering penetrated by the X-ray results.

The image produced is based on the metal’s density penetrated by the X-ray producing a darker picture for denser material and a lighter image for a less dense material. These image helps to analyze the sufficiency of the soldering when compared to quality standards.

The PCB image analysis during X-ray inspection often reveals the defects and the cause of the flaws. The irregularities can range from distorted part placement, inadequate solder paste to inappropriate reflow soldering.

An X-ray inspection is necessary to accurately detect anomalies in hidden areas of BGA assembly, especially for modern electronics.

Some defects often detected during X-ray inspection include solder voids, which usually result from the trapped gas. This trapped can reduce conductivity at the solder joints and the reliability of the connection. To remove these bubbles, vacuum soldering, which is an unusual process, can be used.

Another cause of solder voids can be bad water, and X-ray inspection helps the process engineers identify the causes and eliminate them.


  1. What are the strengths of a PCB X-ray inspection?

The usual point of call for an Automated X-ray Inspection (AXI) during a PCB manufacture is at the soldering point. This is so that defects occurring during the soldering process can be accurately caught and amended. Their suitability for PCB flaw detection over optical inspection methods is their ability to penetrate hidden solder points such as in CSPs, BGAs, and flip chips.

Seeing through the chips to internal solder joints comes easy with Automated X-ray Inspection (AXI). Defects such as solder voids are easily noticed, which might have gone uncaptured using other inspection methods like an optical inspection.

Additional information needed for proper analysis of defects detected is also given by Automated X-ray Inspection (AXI), which ordinarily can not be obtained with optical inspection methods. This is another advantage of AXI over optical inspection systems.

Solder process operations are usually exempted from the purview of optical inspection systems. However, Automated X-ray Inspection (AXI) does not just detect anomalies. Still, it gives insight into the operating processes of the solder joints. Data are provided from parameters like joint size, solder thickness, and profile during inspection to analyze the soldering process and its operation.

PCBs’ manufacturing process is quickly and efficiently optimized when Automated X-ray Inspection (AXI) is used in the manufacturing process. This is due to the early detection of flaws in the first samples, which then informs the adjustment process to avoid repeating the detected faults. This ensures that quality standards are satisfied.

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