BGA X-Ray inspection

Many times smaller EMS companies choose not to invest in x-ray imaging equipment on the factory floor. This discussion will let you know how important to is to perform BGA x-ray inspection. In fact there at least (5) important reasons to make sure that BGA x-ray inspection will be enumerated below.

Step 1: Reason 1- Check for Shorts Post Reflow

BGA x-ray imaging is the right tool to screen for shorts that may be present underneath a BGA or between a BGA and other components. BGA x-ray images can very clearly point out these defects as non common electrical connections can show u distinctly on the x-ray image

Step 2: Reason 2- Check for Consistent Reflow Underneath the Entire Package

The x-ray technician should first have a “birds eye" view of the device post reflow to inspect in areas around the BGA or to inspect the opposite side of the BGA. This shows up to the technician inspecting the x-ray image to see that some solder balls are not the same size as others.. In some cases anomalies can be found where the balls are smaller in certain areas.

Step 3: Reason 3- Check for Any Broken Wire Bonds

With the ever-decreasing thickness of electronic components including BGAs, BGA X-ray inspection will tell you if there are broken wire bonds. This may happen if the boards were not properly baked out prior t rework or of the parts were broken out of the proper packaging master pack and subdivided out by the distributor prior to shipment to the assembler.

Step 4: Reason 4 - Proper Reflow Between the Ball and the Solder Paste

BGA x-ray inspection is done at oblique angle viewing will give you an indication of the proper coalescence of the ball to the solder paste. Improper coalescing of these materials sometimes referred to as “graping” or head-in-pillow is something that will generally not show itself during electrical testing.

Step 5: Reason 5- 100% Inspection for Critical Applications

IPC guidelines indicate that process capabilities can verify the process 100% BGA x-ray inspection will reduce the likelihood of defect escapes. This is particularly true of Class III assemblies or in applications where the proper operation of the BGA is critical to the PCBs’ functioning. BGA x-ray inspection can also determine the void

percentages which are another reliability concern.