BGA X-ray Inspection

1. What is the BGA X-ray inspection?

With the arrival of abundant novel components like BGA, CSP, and flip-chip devices, traditional microscopic examination is not the right option nowadays. The major reason is most of the solder connections in the PCBs are concealed from our view. That’s how real-time X-ray inspection becomes more imperative than ever before.

Usually, soldering defectiveness falls into the following groups:

•       Bridging/Shorts because of an excess solder
•       Dry joints because of an inadequate solder
•       Misalignment/Misplacement due to wrong placement of parts
•       Voiding due to the presence of gas bubbles inside the solder

The comfort of viewing these flaws depends on the resolution of the image. Flaws such as misalignment and bridging can be detected using microscopes. When it comes to voiding, you would require X-ray examination with an image resolution down to one micron, as well as the power in excess of 100W. This type of examination is mandatory for devices like micro-BGAs.

2. What are the BGA defects our machines inspect?

Any supplier of electronic subsystems or OEM in aerospace, electronics, and automotive can improve their inspection method by approving X-ray and CT inspection systems. 

Electrical and electronic components

•       Wire sweep
•       Die attach
•       Lifted ball bonds
•       Broken wedge bonds

Populated and unpopulated PCBs

•       Inspection of CSP, BGAs, and non-lead solders
•       A thorough inspection of vias with the help of multi-layer alignment and hole plating
•       Assess surface mount defects such as bridging, solder joint porosity, and misalignment

Moreover, X-ray equipment reveals all these defects as shown below:

    1.  X-ray image of BGA solder ball joints that display uneven size, shape, and excess voids as the result of poor reflow  

     2. X-ray image of BGA solder ball joints from the oblique angle. It displays varying ball size and shape showing poor reflow. This image also shows void locations within the ball joints.

     3. X-ray image of non-eutectic solder ball along with its accessories to the lowermost board pad as well as the top module joint.

   4.  This X-ray image is an off-axis/compound angle view of solder ball reflow which measures the shape and size of the BGA ball joints.

  5.   This X-ray image is an angled view of BGA solder ball joints with the presence of voids. The tear drop shape of the solder joint occurs due to the reflowed solder drawing off from the cushion to the PCB drop.

3. How do we do an BGA X-ray inspection?

This instruction manual will explain how to fix and use a 2D X-ray system to examine a BGA sample. We will also provide a few hints on what to assess while conducting a BGA X-Ray examination.

Our Uni X-ray inspection system is capable of holding the PCB, ESD wrist strap, ESD smock, and ESD footwear.

•       Step 1: Evaluate client’s priorities –

Evaluate the inspection priorities of the contracting client.

•       Step 2: PCB Elimination –

Eliminate PCB from an immobile shielding bag. Be sure that you are grounded properly while handling an electronic assembly as per the internal company guidelines.

•       Step 3: Label marking –

Find out the area of interest and mark it using a reworked label on that specific area. This marking will help you to locate the source.

•       Step 4: Keeping the BGA into the X-ray chamber –

o   Place the PCB gradually into the x-ray chamber. Don’t forget to follow all the required precautions before operating the X-ray equipment.

o   Switch on the BGA X-ray machine. Remember to maintain enough high contrast in your image. Hence, all opens and voids are in the sight.

o   With the help of a laser pointer in the X-ray machine, deploy the table. By doing so, the region of interest will be displayed on the operator interface X-ray screen.

•   Step 5: Setting up the digital BGA X-ray files –

o   Be sure to set up a folder for video and images before shooting. Next, take more BGA images from varied angles.

o   Place these images inside the appropriate folder for archiving with the job.

•       Step 6: Examination of the BGA X-ray images –

o   Figure out the BGA that requires X-ray inspection. Look out for the flaws like opens, shorts, bridges, etc.

o   As and when you find these anomalies, take snapshots or videos.

o   Examine the BGA completely and zoom into every area of the array device.

o   Check for the evenness of solder ball shape, shorts, sphericity, and other such irregularities.

o   Again, zoom in to check ball size, its consistency, concentricity, voids, as well as other issues.

o   Before wrapping up, analyze the images of the solder ball in a proper pattern once again to make sure that you have covered all the parts of the balls.

•       Step 7: Wrap-Up –

o   After completing the BGA X-ray examination, remove this BGA from the X-ray chamber.

o   Eliminate the rework label and then keep it back into the immobile shielding bag.

4. Why choose us?

We can get you sharp images with a higher resolution of every single position in addition to the reference designator. We even present them as a movie as we move around the given BGA sample from all angles to highlight the anomalies, which are then analyzed by the X-ray technician. 

As we offer a free sample testing provision, you can readily send us your BGA products. Our UNI X-ray technicians will then inspect those BGA samples sent by you. Our X-ray system accepts large thermal mass boards of 160KV plate voltage along with its miniature feature sets measuring about 3um spot size. Our X-ray equipment also inspects micro BGAs and column grid array packages. You will get either a partial report or a full report where the images are partially or fully annotated by our X-ray technicians. We all know that X-ray inspection is a vital step in checking the BGA quality to avoid rework. That’s how our X-ray technicians are highly skilled and experienced at shooting images and assessing product quality.

So, what’s stopping you? Call UNI X-ray immediately. We are always there to provide timely recommendations to cope with your testing requirements.