X-Ray Inspection Report Interpretation Guide

I. Report Overview: The "Eyes" for Inspecting Solder Joint Quality

X-Ray inspection is a non-destructive testing method. It is like taking a “skeletal X-ray image” of your PCBA, clearly revealing the internal structure of solder joints and the underside of components. This report is a key reference for evaluating soldering quality, especially the reliability of hidden solder joints (such as BGA, QFN, and bottom-terminated components).

To ensure the soldering quality of PCBAs using bottom-terminated packages (such as BGA, LGA, and QFN), X-Ray inspection is a critical quality verification method.

Service Trigger Notice: Our system normally identifies such package types and recommends X-Ray inspection. However, the system cannot guarantee 100% accurate identification of all specific components that require this service.

How to View X-Ray Test Results: Please go to Order History → click “Production Progress” → click “X-Ray Report” to download and view the report.

To ensure maximum reliability, if you have special requirements for the soldering quality of certain components, please specify them in the order remarks. We will arrange targeted inspections accordingly. Please note that reports for additional inspection items requested by customers require manual processing and delivery.

II. Detailed Interpretation of Key Report Items

You are advised to focus on the following types of defects:

1. Insufficient Solder / Cold Solder Joints

Acceptable Condition: The solder joint profile is complete, and the grayscale at the contact area with the lead/pad is continuous and uniform.

Points of Concern: Depressed or shriveled solder joint contours, or obvious dark separation lines between the solder and the lead/pad. These conditions may result in poor electrical connection or open circuits and are serious functional defects that usually require repair.

2. Solder Bridging

Acceptable Condition: Clear and complete separation between adjacent solder joints.

Points of Concern: Abnormal gray “bridges” appearing between two or more solder joints that should be isolated. This causes electrical short circuits and is a serious functional defect that must be repaired.

3. Voids in Solder Joints

Acceptable Condition: Uniform grayscale, with full and smooth solder joint contours.

Points of Concern: Black spots or dark areas inside the solder joint indicate “voids,” which are residual gases formed during soldering. Small, scattered, and minor voids are generally acceptable. However, large voids (for example, exceeding 25% of the joint area) or voids concentrated in current paths or high-stress regions can weaken mechanical strength and current-carrying capability.

4. Solder Ball Misalignment

Acceptable Condition: For components such as BGA, the image of each solder ball is well aligned with the corresponding PCB pad.

Points of Concern: Obvious misalignment between solder balls and pads. Minor offsets may fall within process tolerances, but severe misalignment can cause poor electrical connections or short circuits.

5. Non-Uniform Solder Balls

Acceptable Condition: All solder balls on the same component (such as BGA) are uniform in size, shape, and grayscale.

Points of Concern: Inconsistent ball sizes or irregular shapes (such as elliptical forms). This may indicate uneven reflow temperature profiles, inconsistent solder paste volume, or pad design issues.

III. Summary

For PCBAs containing complex packages such as BGAs, X-Ray inspection is a critical step in ensuring product reliability. Understanding this report helps you communicate more professionally with us and work together to ensure successful product delivery.